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Diffstat (limited to '')
| -rw-r--r-- | third_party/libsrtp/src/srtp/srtp.c | 4723 |
1 files changed, 4723 insertions, 0 deletions
diff --git a/third_party/libsrtp/src/srtp/srtp.c b/third_party/libsrtp/src/srtp/srtp.c new file mode 100644 index 0000000000..fc0b1b0ad1 --- /dev/null +++ b/third_party/libsrtp/src/srtp/srtp.c @@ -0,0 +1,4723 @@ +/* + * srtp.c + * + * the secure real-time transport protocol + * + * David A. McGrew + * Cisco Systems, Inc. + */ +/* + * + * Copyright (c) 2001-2017, Cisco Systems, Inc. + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * + * Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * + * Redistributions in binary form must reproduce the above + * copyright notice, this list of conditions and the following + * disclaimer in the documentation and/or other materials provided + * with the distribution. + * + * Neither the name of the Cisco Systems, Inc. nor the names of its + * contributors may be used to endorse or promote products derived + * from this software without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS + * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT + * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS + * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE + * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, + * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES + * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR + * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, + * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) + * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED + * OF THE POSSIBILITY OF SUCH DAMAGE. + * + */ + +// Leave this as the top level import. Ensures the existence of defines +#include "config.h" + +#include "srtp_priv.h" +#include "crypto_types.h" +#include "err.h" +#include "alloc.h" /* for srtp_crypto_alloc() */ + +#ifdef GCM +#include "aes_gcm.h" /* for AES GCM mode */ +#endif + +#ifdef OPENSSL_KDF +#include <openssl/kdf.h> +#include "aes_icm_ext.h" +#endif + +#include <limits.h> +#ifdef HAVE_NETINET_IN_H +#include <netinet/in.h> +#elif defined(HAVE_WINSOCK2_H) +#include <winsock2.h> +#endif + +/* the debug module for srtp */ +srtp_debug_module_t mod_srtp = { + 0, /* debugging is off by default */ + "srtp" /* printable name for module */ +}; + +#define octets_in_rtp_header 12 +#define uint32s_in_rtp_header 3 +#define octets_in_rtcp_header 8 +#define uint32s_in_rtcp_header 2 +#define octets_in_rtp_extn_hdr 4 + +static srtp_err_status_t srtp_validate_rtp_header(void *rtp_hdr, + int *pkt_octet_len) +{ + srtp_hdr_t *hdr = (srtp_hdr_t *)rtp_hdr; + int rtp_header_len; + + if (*pkt_octet_len < octets_in_rtp_header) + return srtp_err_status_bad_param; + + /* Check RTP header length */ + rtp_header_len = octets_in_rtp_header + 4 * hdr->cc; + if (hdr->x == 1) + rtp_header_len += octets_in_rtp_extn_hdr; + + if (*pkt_octet_len < rtp_header_len) + return srtp_err_status_bad_param; + + /* Verifing profile length. */ + if (hdr->x == 1) { + srtp_hdr_xtnd_t *xtn_hdr = + (srtp_hdr_xtnd_t *)((uint32_t *)hdr + uint32s_in_rtp_header + + hdr->cc); + int profile_len = ntohs(xtn_hdr->length); + rtp_header_len += profile_len * 4; + /* profile length counts the number of 32-bit words */ + if (*pkt_octet_len < rtp_header_len) + return srtp_err_status_bad_param; + } + return srtp_err_status_ok; +} + +const char *srtp_get_version_string() +{ + /* + * Simply return the autotools generated string + */ + return SRTP_VER_STRING; +} + +unsigned int srtp_get_version() +{ + unsigned int major = 0, minor = 0, micro = 0; + unsigned int rv = 0; + int parse_rv; + + /* + * Parse the autotools generated version + */ + parse_rv = sscanf(SRTP_VERSION, "%u.%u.%u", &major, &minor, µ); + if (parse_rv != 3) { + /* + * We're expected to parse all 3 version levels. + * If not, then this must not be an official release. + * Return all zeros on the version + */ + return (0); + } + + /* + * We allow 8 bits for the major and minor, while + * allowing 16 bits for the micro. 16 bits for the micro + * may be beneficial for a continuous delivery model + * in the future. + */ + rv |= (major & 0xFF) << 24; + rv |= (minor & 0xFF) << 16; + rv |= micro & 0xFF; + return rv; +} + +srtp_err_status_t srtp_stream_dealloc(srtp_stream_ctx_t *stream, + const srtp_stream_ctx_t *stream_template) +{ + srtp_err_status_t status; + unsigned int i = 0; + srtp_session_keys_t *session_keys = NULL; + srtp_session_keys_t *template_session_keys = NULL; + + /* + * we use a conservative deallocation strategy - if any deallocation + * fails, then we report that fact without trying to deallocate + * anything else + */ + if (stream->session_keys) { + for (i = 0; i < stream->num_master_keys; i++) { + session_keys = &stream->session_keys[i]; + + if (stream_template && + stream->num_master_keys == stream_template->num_master_keys) { + template_session_keys = &stream_template->session_keys[i]; + } else { + template_session_keys = NULL; + } + + /* + * deallocate cipher, if it is not the same as that in template + */ + if (template_session_keys && + session_keys->rtp_cipher == template_session_keys->rtp_cipher) { + /* do nothing */ + } else if (session_keys->rtp_cipher) { + status = srtp_cipher_dealloc(session_keys->rtp_cipher); + if (status) + return status; + } + + /* + * deallocate auth function, if it is not the same as that in + * template + */ + if (template_session_keys && + session_keys->rtp_auth == template_session_keys->rtp_auth) { + /* do nothing */ + } else if (session_keys->rtp_auth) { + status = srtp_auth_dealloc(session_keys->rtp_auth); + if (status) + return status; + } + + if (template_session_keys && + session_keys->rtp_xtn_hdr_cipher == + template_session_keys->rtp_xtn_hdr_cipher) { + /* do nothing */ + } else if (session_keys->rtp_xtn_hdr_cipher) { + status = srtp_cipher_dealloc(session_keys->rtp_xtn_hdr_cipher); + if (status) + return status; + } + + /* + * deallocate rtcp cipher, if it is not the same as that in + * template + */ + if (template_session_keys && + session_keys->rtcp_cipher == + template_session_keys->rtcp_cipher) { + /* do nothing */ + } else if (session_keys->rtcp_cipher) { + status = srtp_cipher_dealloc(session_keys->rtcp_cipher); + if (status) + return status; + } + + /* + * deallocate rtcp auth function, if it is not the same as that in + * template + */ + if (template_session_keys && + session_keys->rtcp_auth == template_session_keys->rtcp_auth) { + /* do nothing */ + } else if (session_keys->rtcp_auth) { + status = srtp_auth_dealloc(session_keys->rtcp_auth); + if (status) + return status; + } + + /* + * zeroize the salt value + */ + octet_string_set_to_zero(session_keys->salt, SRTP_AEAD_SALT_LEN); + octet_string_set_to_zero(session_keys->c_salt, SRTP_AEAD_SALT_LEN); + + if (session_keys->mki_id) { + octet_string_set_to_zero(session_keys->mki_id, + session_keys->mki_size); + srtp_crypto_free(session_keys->mki_id); + session_keys->mki_id = NULL; + } + + /* + * deallocate key usage limit, if it is not the same as that in + * template + */ + if (template_session_keys && + session_keys->limit == template_session_keys->limit) { + /* do nothing */ + } else if (session_keys->limit) { + srtp_crypto_free(session_keys->limit); + } + } + srtp_crypto_free(stream->session_keys); + } + + status = srtp_rdbx_dealloc(&stream->rtp_rdbx); + if (status) + return status; + + if (stream_template && + stream->enc_xtn_hdr == stream_template->enc_xtn_hdr) { + /* do nothing */ + } else if (stream->enc_xtn_hdr) { + srtp_crypto_free(stream->enc_xtn_hdr); + } + + /* deallocate srtp stream context */ + srtp_crypto_free(stream); + + return srtp_err_status_ok; +} + +static srtp_err_status_t srtp_valid_policy(const srtp_policy_t *p) +{ + if (p != NULL && p->deprecated_ekt != NULL) { + return srtp_err_status_bad_param; + } + + return srtp_err_status_ok; +} + +srtp_err_status_t srtp_stream_alloc(srtp_stream_ctx_t **str_ptr, + const srtp_policy_t *p) +{ + srtp_stream_ctx_t *str; + srtp_err_status_t stat; + unsigned int i = 0; + srtp_session_keys_t *session_keys = NULL; + + stat = srtp_valid_policy(p); + if (stat != srtp_err_status_ok) { + return stat; + } + + /* + * This function allocates the stream context, rtp and rtcp ciphers + * and auth functions, and key limit structure. If there is a + * failure during allocation, we free all previously allocated + * memory and return a failure code. The code could probably + * be improved, but it works and should be clear. + */ + + /* allocate srtp stream and set str_ptr */ + str = (srtp_stream_ctx_t *)srtp_crypto_alloc(sizeof(srtp_stream_ctx_t)); + if (str == NULL) + return srtp_err_status_alloc_fail; + + *str_ptr = str; + + /* + *To keep backwards API compatible if someone is using multiple master + * keys then key should be set to NULL + */ + if (p->key != NULL) { + str->num_master_keys = 1; + } else { + str->num_master_keys = p->num_master_keys; + } + + str->session_keys = (srtp_session_keys_t *)srtp_crypto_alloc( + sizeof(srtp_session_keys_t) * str->num_master_keys); + + if (str->session_keys == NULL) { + srtp_stream_dealloc(str, NULL); + return srtp_err_status_alloc_fail; + } + + for (i = 0; i < str->num_master_keys; i++) { + session_keys = &str->session_keys[i]; + + /* allocate cipher */ + stat = srtp_crypto_kernel_alloc_cipher( + p->rtp.cipher_type, &session_keys->rtp_cipher, + p->rtp.cipher_key_len, p->rtp.auth_tag_len); + if (stat) { + srtp_stream_dealloc(str, NULL); + return stat; + } + + /* allocate auth function */ + stat = srtp_crypto_kernel_alloc_auth( + p->rtp.auth_type, &session_keys->rtp_auth, p->rtp.auth_key_len, + p->rtp.auth_tag_len); + if (stat) { + srtp_stream_dealloc(str, NULL); + return stat; + } + + /* + * ...and now the RTCP-specific initialization - first, allocate + * the cipher + */ + stat = srtp_crypto_kernel_alloc_cipher( + p->rtcp.cipher_type, &session_keys->rtcp_cipher, + p->rtcp.cipher_key_len, p->rtcp.auth_tag_len); + if (stat) { + srtp_stream_dealloc(str, NULL); + return stat; + } + + /* allocate auth function */ + stat = srtp_crypto_kernel_alloc_auth( + p->rtcp.auth_type, &session_keys->rtcp_auth, p->rtcp.auth_key_len, + p->rtcp.auth_tag_len); + if (stat) { + srtp_stream_dealloc(str, NULL); + return stat; + } + + session_keys->mki_id = NULL; + + /* allocate key limit structure */ + session_keys->limit = (srtp_key_limit_ctx_t *)srtp_crypto_alloc( + sizeof(srtp_key_limit_ctx_t)); + if (session_keys->limit == NULL) { + srtp_stream_dealloc(str, NULL); + return srtp_err_status_alloc_fail; + } + } + + if (p->enc_xtn_hdr && p->enc_xtn_hdr_count > 0) { + srtp_cipher_type_id_t enc_xtn_hdr_cipher_type; + int enc_xtn_hdr_cipher_key_len; + + str->enc_xtn_hdr = (int *)srtp_crypto_alloc(p->enc_xtn_hdr_count * + sizeof(p->enc_xtn_hdr[0])); + if (!str->enc_xtn_hdr) { + srtp_stream_dealloc(str, NULL); + return srtp_err_status_alloc_fail; + } + memcpy(str->enc_xtn_hdr, p->enc_xtn_hdr, + p->enc_xtn_hdr_count * sizeof(p->enc_xtn_hdr[0])); + str->enc_xtn_hdr_count = p->enc_xtn_hdr_count; + + /* + * For GCM ciphers, the corresponding ICM cipher is used for header + * extensions encryption. + */ + switch (p->rtp.cipher_type) { + case SRTP_AES_GCM_128: + enc_xtn_hdr_cipher_type = SRTP_AES_ICM_128; + enc_xtn_hdr_cipher_key_len = SRTP_AES_ICM_128_KEY_LEN_WSALT; + break; + case SRTP_AES_GCM_256: + enc_xtn_hdr_cipher_type = SRTP_AES_ICM_256; + enc_xtn_hdr_cipher_key_len = SRTP_AES_ICM_256_KEY_LEN_WSALT; + break; + default: + enc_xtn_hdr_cipher_type = p->rtp.cipher_type; + enc_xtn_hdr_cipher_key_len = p->rtp.cipher_key_len; + break; + } + + for (i = 0; i < str->num_master_keys; i++) { + session_keys = &str->session_keys[i]; + + /* allocate cipher for extensions header encryption */ + stat = srtp_crypto_kernel_alloc_cipher( + enc_xtn_hdr_cipher_type, &session_keys->rtp_xtn_hdr_cipher, + enc_xtn_hdr_cipher_key_len, 0); + if (stat) { + srtp_stream_dealloc(str, NULL); + return stat; + } + } + } else { + for (i = 0; i < str->num_master_keys; i++) { + session_keys = &str->session_keys[i]; + session_keys->rtp_xtn_hdr_cipher = NULL; + } + + str->enc_xtn_hdr = NULL; + str->enc_xtn_hdr_count = 0; + } + + return srtp_err_status_ok; +} + +/* + * srtp_stream_clone(stream_template, new) allocates a new stream and + * initializes it using the cipher and auth of the stream_template + * + * the only unique data in a cloned stream is the replay database and + * the SSRC + */ + +srtp_err_status_t srtp_stream_clone(const srtp_stream_ctx_t *stream_template, + uint32_t ssrc, + srtp_stream_ctx_t **str_ptr) +{ + srtp_err_status_t status; + srtp_stream_ctx_t *str; + unsigned int i = 0; + srtp_session_keys_t *session_keys = NULL; + const srtp_session_keys_t *template_session_keys = NULL; + + debug_print(mod_srtp, "cloning stream (SSRC: 0x%08x)", ntohl(ssrc)); + + /* allocate srtp stream and set str_ptr */ + str = (srtp_stream_ctx_t *)srtp_crypto_alloc(sizeof(srtp_stream_ctx_t)); + if (str == NULL) + return srtp_err_status_alloc_fail; + *str_ptr = str; + + str->num_master_keys = stream_template->num_master_keys; + str->session_keys = (srtp_session_keys_t *)srtp_crypto_alloc( + sizeof(srtp_session_keys_t) * str->num_master_keys); + + if (str->session_keys == NULL) { + srtp_stream_dealloc(*str_ptr, stream_template); + *str_ptr = NULL; + return srtp_err_status_alloc_fail; + } + + for (i = 0; i < stream_template->num_master_keys; i++) { + session_keys = &str->session_keys[i]; + template_session_keys = &stream_template->session_keys[i]; + + /* set cipher and auth pointers to those of the template */ + session_keys->rtp_cipher = template_session_keys->rtp_cipher; + session_keys->rtp_auth = template_session_keys->rtp_auth; + session_keys->rtp_xtn_hdr_cipher = + template_session_keys->rtp_xtn_hdr_cipher; + session_keys->rtcp_cipher = template_session_keys->rtcp_cipher; + session_keys->rtcp_auth = template_session_keys->rtcp_auth; + session_keys->mki_size = template_session_keys->mki_size; + + if (template_session_keys->mki_size == 0) { + session_keys->mki_id = NULL; + } else { + session_keys->mki_id = + srtp_crypto_alloc(template_session_keys->mki_size); + + if (session_keys->mki_id == NULL) { + srtp_stream_dealloc(*str_ptr, stream_template); + *str_ptr = NULL; + return srtp_err_status_init_fail; + } + memcpy(session_keys->mki_id, template_session_keys->mki_id, + session_keys->mki_size); + } + /* Copy the salt values */ + memcpy(session_keys->salt, template_session_keys->salt, + SRTP_AEAD_SALT_LEN); + memcpy(session_keys->c_salt, template_session_keys->c_salt, + SRTP_AEAD_SALT_LEN); + + /* set key limit to point to that of the template */ + status = srtp_key_limit_clone(template_session_keys->limit, + &session_keys->limit); + if (status) { + srtp_stream_dealloc(*str_ptr, stream_template); + *str_ptr = NULL; + return status; + } + } + + /* initialize replay databases */ + status = srtp_rdbx_init( + &str->rtp_rdbx, srtp_rdbx_get_window_size(&stream_template->rtp_rdbx)); + if (status) { + srtp_stream_dealloc(*str_ptr, stream_template); + *str_ptr = NULL; + return status; + } + srtp_rdb_init(&str->rtcp_rdb); + str->allow_repeat_tx = stream_template->allow_repeat_tx; + + /* set ssrc to that provided */ + str->ssrc = ssrc; + + /* reset pending ROC */ + str->pending_roc = 0; + + /* set direction and security services */ + str->direction = stream_template->direction; + str->rtp_services = stream_template->rtp_services; + str->rtcp_services = stream_template->rtcp_services; + + /* copy information about extensions header encryption */ + str->enc_xtn_hdr = stream_template->enc_xtn_hdr; + str->enc_xtn_hdr_count = stream_template->enc_xtn_hdr_count; + + /* defensive coding */ + str->next = NULL; + return srtp_err_status_ok; +} + +/* + * key derivation functions, internal to libSRTP + * + * srtp_kdf_t is a key derivation context + * + * srtp_kdf_init(&kdf, cipher_id, k, keylen) initializes kdf to use cipher + * described by cipher_id, with the master key k with length in octets keylen. + * + * srtp_kdf_generate(&kdf, l, kl, keylen) derives the key + * corresponding to label l and puts it into kl; the length + * of the key in octets is provided as keylen. this function + * should be called once for each subkey that is derived. + * + * srtp_kdf_clear(&kdf) zeroizes and deallocates the kdf state + */ + +typedef enum { + label_rtp_encryption = 0x00, + label_rtp_msg_auth = 0x01, + label_rtp_salt = 0x02, + label_rtcp_encryption = 0x03, + label_rtcp_msg_auth = 0x04, + label_rtcp_salt = 0x05, + label_rtp_header_encryption = 0x06, + label_rtp_header_salt = 0x07 +} srtp_prf_label; + +#define MAX_SRTP_KEY_LEN 256 + +#if defined(OPENSSL) && defined(OPENSSL_KDF) +#define MAX_SRTP_AESKEY_LEN 32 +#define MAX_SRTP_SALT_LEN 14 + +/* + * srtp_kdf_t represents a key derivation function. The SRTP + * default KDF is the only one implemented at present. + */ +typedef struct { + uint8_t master_key[MAX_SRTP_AESKEY_LEN]; + uint8_t master_salt[MAX_SRTP_SALT_LEN]; + const EVP_CIPHER *evp; +} srtp_kdf_t; + +static srtp_err_status_t srtp_kdf_init(srtp_kdf_t *kdf, + const uint8_t *key, + int key_len, + int salt_len) +{ + memset(kdf, 0x0, sizeof(srtp_kdf_t)); + + /* The NULL cipher has zero key length */ + if (key_len == 0) + return srtp_err_status_ok; + + if ((key_len > MAX_SRTP_AESKEY_LEN) || (salt_len > MAX_SRTP_SALT_LEN)) { + return srtp_err_status_bad_param; + } + switch (key_len) { + case SRTP_AES_256_KEYSIZE: + kdf->evp = EVP_aes_256_ctr(); + break; + case SRTP_AES_192_KEYSIZE: + kdf->evp = EVP_aes_192_ctr(); + break; + case SRTP_AES_128_KEYSIZE: + kdf->evp = EVP_aes_128_ctr(); + break; + default: + return srtp_err_status_bad_param; + break; + } + memcpy(kdf->master_key, key, key_len); + memcpy(kdf->master_salt, key + key_len, salt_len); + return srtp_err_status_ok; +} + +static srtp_err_status_t srtp_kdf_generate(srtp_kdf_t *kdf, + srtp_prf_label label, + uint8_t *key, + unsigned int length) +{ + int ret; + + /* The NULL cipher will not have an EVP */ + if (!kdf->evp) + return srtp_err_status_ok; + octet_string_set_to_zero(key, length); + + /* + * Invoke the OpenSSL SRTP KDF function + * This is useful if OpenSSL is in FIPS mode and FIP + * compliance is required for SRTP. + */ + ret = kdf_srtp(kdf->evp, (char *)&kdf->master_key, + (char *)&kdf->master_salt, NULL, NULL, label, (char *)key); + if (ret == -1) { + return (srtp_err_status_algo_fail); + } + + return srtp_err_status_ok; +} + +static srtp_err_status_t srtp_kdf_clear(srtp_kdf_t *kdf) +{ + octet_string_set_to_zero(kdf->master_key, MAX_SRTP_AESKEY_LEN); + octet_string_set_to_zero(kdf->master_salt, MAX_SRTP_SALT_LEN); + kdf->evp = NULL; + + return srtp_err_status_ok; +} + +#else /* if OPENSSL_KDF */ + +/* + * srtp_kdf_t represents a key derivation function. The SRTP + * default KDF is the only one implemented at present. + */ +typedef struct { + srtp_cipher_t *cipher; /* cipher used for key derivation */ +} srtp_kdf_t; + +static srtp_err_status_t srtp_kdf_init(srtp_kdf_t *kdf, + const uint8_t *key, + int key_len) +{ + srtp_cipher_type_id_t cipher_id; + srtp_err_status_t stat; + + switch (key_len) { + case SRTP_AES_ICM_256_KEY_LEN_WSALT: + cipher_id = SRTP_AES_ICM_256; + break; + case SRTP_AES_ICM_192_KEY_LEN_WSALT: + cipher_id = SRTP_AES_ICM_192; + break; + case SRTP_AES_ICM_128_KEY_LEN_WSALT: + cipher_id = SRTP_AES_ICM_128; + break; + default: + return srtp_err_status_bad_param; + break; + } + + stat = srtp_crypto_kernel_alloc_cipher(cipher_id, &kdf->cipher, key_len, 0); + if (stat) + return stat; + + stat = srtp_cipher_init(kdf->cipher, key); + if (stat) { + srtp_cipher_dealloc(kdf->cipher); + return stat; + } + return srtp_err_status_ok; +} + +static srtp_err_status_t srtp_kdf_generate(srtp_kdf_t *kdf, + srtp_prf_label label, + uint8_t *key, + unsigned int length) +{ + srtp_err_status_t status; + v128_t nonce; + + /* set eigth octet of nonce to <label>, set the rest of it to zero */ + v128_set_to_zero(&nonce); + nonce.v8[7] = label; + + status = srtp_cipher_set_iv(kdf->cipher, (uint8_t *)&nonce, + srtp_direction_encrypt); + if (status) + return status; + + /* generate keystream output */ + octet_string_set_to_zero(key, length); + status = srtp_cipher_encrypt(kdf->cipher, key, &length); + if (status) + return status; + + return srtp_err_status_ok; +} + +static srtp_err_status_t srtp_kdf_clear(srtp_kdf_t *kdf) +{ + srtp_err_status_t status; + status = srtp_cipher_dealloc(kdf->cipher); + if (status) + return status; + kdf->cipher = NULL; + return srtp_err_status_ok; +} +#endif /* else OPENSSL_KDF */ + +/* + * end of key derivation functions + */ + +/* Get the base key length corresponding to a given combined key+salt + * length for the given cipher. + * TODO: key and salt lengths should be separate fields in the policy. */ +static inline int base_key_length(const srtp_cipher_type_t *cipher, + int key_length) +{ + switch (cipher->id) { + case SRTP_NULL_CIPHER: + return 0; + case SRTP_AES_ICM_128: + case SRTP_AES_ICM_192: + case SRTP_AES_ICM_256: + /* The legacy modes are derived from + * the configured key length on the policy */ + return key_length - SRTP_SALT_LEN; + case SRTP_AES_GCM_128: + return key_length - SRTP_AEAD_SALT_LEN; + case SRTP_AES_GCM_256: + return key_length - SRTP_AEAD_SALT_LEN; + default: + return key_length; + } +} + +/* Get the key length that the application should supply for the given cipher */ +static inline int full_key_length(const srtp_cipher_type_t *cipher) +{ + switch (cipher->id) { + case SRTP_NULL_CIPHER: + case SRTP_AES_ICM_128: + return SRTP_AES_ICM_128_KEY_LEN_WSALT; + case SRTP_AES_ICM_192: + return SRTP_AES_ICM_192_KEY_LEN_WSALT; + case SRTP_AES_ICM_256: + return SRTP_AES_ICM_256_KEY_LEN_WSALT; + case SRTP_AES_GCM_128: + return SRTP_AES_GCM_128_KEY_LEN_WSALT; + case SRTP_AES_GCM_256: + return SRTP_AES_GCM_256_KEY_LEN_WSALT; + default: + return 0; + } +} + +unsigned int srtp_validate_policy_master_keys(const srtp_policy_t *policy) +{ + unsigned long i = 0; + + if (policy->key == NULL) { + if (policy->num_master_keys <= 0) + return 0; + + if (policy->num_master_keys > SRTP_MAX_NUM_MASTER_KEYS) + return 0; + + for (i = 0; i < policy->num_master_keys; i++) { + if (policy->keys[i]->key == NULL) + return 0; + if (policy->keys[i]->mki_size > SRTP_MAX_MKI_LEN) + return 0; + } + } + + return 1; +} + +srtp_session_keys_t *srtp_get_session_keys_with_mki_index( + srtp_stream_ctx_t *stream, + unsigned int use_mki, + unsigned int mki_index) +{ + if (use_mki) { + if (mki_index >= stream->num_master_keys) { + return NULL; + } + return &stream->session_keys[mki_index]; + } + + return &stream->session_keys[0]; +} + +unsigned int srtp_inject_mki(uint8_t *mki_tag_location, + srtp_session_keys_t *session_keys, + unsigned int use_mki) +{ + unsigned int mki_size = 0; + + if (use_mki) { + mki_size = session_keys->mki_size; + + if (mki_size != 0) { + // Write MKI into memory + memcpy(mki_tag_location, session_keys->mki_id, mki_size); + } + } + + return mki_size; +} + +srtp_err_status_t srtp_stream_init_all_master_keys( + srtp_stream_ctx_t *srtp, + unsigned char *key, + srtp_master_key_t **keys, + const unsigned int max_master_keys) +{ + unsigned int i = 0; + srtp_err_status_t status = srtp_err_status_ok; + srtp_master_key_t single_master_key; + + if (key != NULL) { + srtp->num_master_keys = 1; + single_master_key.key = key; + single_master_key.mki_id = NULL; + single_master_key.mki_size = 0; + status = srtp_stream_init_keys(srtp, &single_master_key, 0); + } else { + srtp->num_master_keys = max_master_keys; + + for (i = 0; i < srtp->num_master_keys && i < SRTP_MAX_NUM_MASTER_KEYS; + i++) { + status = srtp_stream_init_keys(srtp, keys[i], i); + + if (status) { + return status; + } + } + } + + return status; +} + +srtp_err_status_t srtp_stream_init_keys(srtp_stream_ctx_t *srtp, + srtp_master_key_t *master_key, + const unsigned int current_mki_index) +{ + srtp_err_status_t stat; + srtp_kdf_t kdf; + uint8_t tmp_key[MAX_SRTP_KEY_LEN]; + int input_keylen, input_keylen_rtcp; + int kdf_keylen = 30, rtp_keylen, rtcp_keylen; + int rtp_base_key_len, rtp_salt_len; + int rtcp_base_key_len, rtcp_salt_len; + srtp_session_keys_t *session_keys = NULL; + unsigned char *key = master_key->key; + + /* If RTP or RTCP have a key length > AES-128, assume matching kdf. */ + /* TODO: kdf algorithm, master key length, and master salt length should + * be part of srtp_policy_t. + */ + session_keys = &srtp->session_keys[current_mki_index]; + +/* initialize key limit to maximum value */ +#ifdef NO_64BIT_MATH + { + uint64_t temp; + temp = make64(UINT_MAX, UINT_MAX); + srtp_key_limit_set(session_keys->limit, temp); + } +#else + srtp_key_limit_set(session_keys->limit, 0xffffffffffffLL); +#endif + + if (master_key->mki_size != 0) { + session_keys->mki_id = srtp_crypto_alloc(master_key->mki_size); + + if (session_keys->mki_id == NULL) { + return srtp_err_status_init_fail; + } + memcpy(session_keys->mki_id, master_key->mki_id, master_key->mki_size); + } else { + session_keys->mki_id = NULL; + } + + session_keys->mki_size = master_key->mki_size; + + input_keylen = full_key_length(session_keys->rtp_cipher->type); + input_keylen_rtcp = full_key_length(session_keys->rtcp_cipher->type); + if (input_keylen_rtcp > input_keylen) { + input_keylen = input_keylen_rtcp; + } + + rtp_keylen = srtp_cipher_get_key_length(session_keys->rtp_cipher); + rtcp_keylen = srtp_cipher_get_key_length(session_keys->rtcp_cipher); + rtp_base_key_len = + base_key_length(session_keys->rtp_cipher->type, rtp_keylen); + rtp_salt_len = rtp_keylen - rtp_base_key_len; + + if (rtp_keylen > kdf_keylen) { + kdf_keylen = 46; /* AES-CTR mode is always used for KDF */ + } + + if (rtcp_keylen > kdf_keylen) { + kdf_keylen = 46; /* AES-CTR mode is always used for KDF */ + } + + if (input_keylen > kdf_keylen) { + kdf_keylen = 46; /* AES-CTR mode is always used for KDF */ + } + + debug_print(mod_srtp, "input key len: %d", input_keylen); + debug_print(mod_srtp, "srtp key len: %d", rtp_keylen); + debug_print(mod_srtp, "srtcp key len: %d", rtcp_keylen); + debug_print(mod_srtp, "base key len: %d", rtp_base_key_len); + debug_print(mod_srtp, "kdf key len: %d", kdf_keylen); + debug_print(mod_srtp, "rtp salt len: %d", rtp_salt_len); + + /* + * Make sure the key given to us is 'zero' appended. GCM + * mode uses a shorter master SALT (96 bits), but still relies on + * the legacy CTR mode KDF, which uses a 112 bit master SALT. + */ + memset(tmp_key, 0x0, MAX_SRTP_KEY_LEN); + memcpy(tmp_key, key, input_keylen); + +/* initialize KDF state */ +#if defined(OPENSSL) && defined(OPENSSL_KDF) + stat = srtp_kdf_init(&kdf, (const uint8_t *)tmp_key, rtp_base_key_len, + rtp_salt_len); +#else + stat = srtp_kdf_init(&kdf, (const uint8_t *)tmp_key, kdf_keylen); +#endif + if (stat) { + /* zeroize temp buffer */ + octet_string_set_to_zero(tmp_key, MAX_SRTP_KEY_LEN); + return srtp_err_status_init_fail; + } + + /* generate encryption key */ + stat = srtp_kdf_generate(&kdf, label_rtp_encryption, tmp_key, + rtp_base_key_len); + if (stat) { + /* zeroize temp buffer */ + octet_string_set_to_zero(tmp_key, MAX_SRTP_KEY_LEN); + return srtp_err_status_init_fail; + } + debug_print(mod_srtp, "cipher key: %s", + srtp_octet_string_hex_string(tmp_key, rtp_base_key_len)); + + /* + * if the cipher in the srtp context uses a salt, then we need + * to generate the salt value + */ + if (rtp_salt_len > 0) { + debug_print0(mod_srtp, "found rtp_salt_len > 0, generating salt"); + + /* generate encryption salt, put after encryption key */ + stat = srtp_kdf_generate(&kdf, label_rtp_salt, + tmp_key + rtp_base_key_len, rtp_salt_len); + if (stat) { + /* zeroize temp buffer */ + octet_string_set_to_zero(tmp_key, MAX_SRTP_KEY_LEN); + return srtp_err_status_init_fail; + } + memcpy(session_keys->salt, tmp_key + rtp_base_key_len, + SRTP_AEAD_SALT_LEN); + } + if (rtp_salt_len > 0) { + debug_print(mod_srtp, "cipher salt: %s", + srtp_octet_string_hex_string(tmp_key + rtp_base_key_len, + rtp_salt_len)); + } + + /* initialize cipher */ + stat = srtp_cipher_init(session_keys->rtp_cipher, tmp_key); + if (stat) { + /* zeroize temp buffer */ + octet_string_set_to_zero(tmp_key, MAX_SRTP_KEY_LEN); + return srtp_err_status_init_fail; + } + + if (session_keys->rtp_xtn_hdr_cipher) { + /* generate extensions header encryption key */ + int rtp_xtn_hdr_keylen; + int rtp_xtn_hdr_base_key_len; + int rtp_xtn_hdr_salt_len; + srtp_kdf_t tmp_kdf; + srtp_kdf_t *xtn_hdr_kdf; + + if (session_keys->rtp_xtn_hdr_cipher->type != + session_keys->rtp_cipher->type) { + /* + * With GCM ciphers, the header extensions are still encrypted using + * the corresponding ICM cipher. + * See https://tools.ietf.org/html/rfc7714#section-8.3 + */ + uint8_t tmp_xtn_hdr_key[MAX_SRTP_KEY_LEN]; + rtp_xtn_hdr_keylen = + srtp_cipher_get_key_length(session_keys->rtp_xtn_hdr_cipher); + rtp_xtn_hdr_base_key_len = base_key_length( + session_keys->rtp_xtn_hdr_cipher->type, rtp_xtn_hdr_keylen); + rtp_xtn_hdr_salt_len = + rtp_xtn_hdr_keylen - rtp_xtn_hdr_base_key_len; + if (rtp_xtn_hdr_salt_len > rtp_salt_len) { + switch (session_keys->rtp_cipher->type->id) { + case SRTP_AES_GCM_128: + case SRTP_AES_GCM_256: + /* + * The shorter GCM salt is padded to the required ICM salt + * length. + */ + rtp_xtn_hdr_salt_len = rtp_salt_len; + break; + default: + /* zeroize temp buffer */ + octet_string_set_to_zero(tmp_key, MAX_SRTP_KEY_LEN); + return srtp_err_status_bad_param; + } + } + memset(tmp_xtn_hdr_key, 0x0, MAX_SRTP_KEY_LEN); + memcpy(tmp_xtn_hdr_key, key, + (rtp_xtn_hdr_base_key_len + rtp_xtn_hdr_salt_len)); + xtn_hdr_kdf = &tmp_kdf; + +/* initialize KDF state */ +#if defined(OPENSSL) && defined(OPENSSL_KDF) + stat = + srtp_kdf_init(xtn_hdr_kdf, (const uint8_t *)tmp_xtn_hdr_key, + rtp_xtn_hdr_base_key_len, rtp_xtn_hdr_salt_len); +#else + stat = srtp_kdf_init(xtn_hdr_kdf, (const uint8_t *)tmp_xtn_hdr_key, + kdf_keylen); +#endif + octet_string_set_to_zero(tmp_xtn_hdr_key, MAX_SRTP_KEY_LEN); + if (stat) { + /* zeroize temp buffer */ + octet_string_set_to_zero(tmp_key, MAX_SRTP_KEY_LEN); + return srtp_err_status_init_fail; + } + } else { + /* Reuse main KDF. */ + rtp_xtn_hdr_keylen = rtp_keylen; + rtp_xtn_hdr_base_key_len = rtp_base_key_len; + rtp_xtn_hdr_salt_len = rtp_salt_len; + xtn_hdr_kdf = &kdf; + } + + stat = srtp_kdf_generate(xtn_hdr_kdf, label_rtp_header_encryption, + tmp_key, rtp_xtn_hdr_base_key_len); + if (stat) { + /* zeroize temp buffer */ + octet_string_set_to_zero(tmp_key, MAX_SRTP_KEY_LEN); + return srtp_err_status_init_fail; + } + debug_print( + mod_srtp, "extensions cipher key: %s", + srtp_octet_string_hex_string(tmp_key, rtp_xtn_hdr_base_key_len)); + + /* + * if the cipher in the srtp context uses a salt, then we need + * to generate the salt value + */ + if (rtp_xtn_hdr_salt_len > 0) { + debug_print0(mod_srtp, + "found rtp_xtn_hdr_salt_len > 0, generating salt"); + + /* generate encryption salt, put after encryption key */ + stat = srtp_kdf_generate(xtn_hdr_kdf, label_rtp_header_salt, + tmp_key + rtp_xtn_hdr_base_key_len, + rtp_xtn_hdr_salt_len); + if (stat) { + /* zeroize temp buffer */ + octet_string_set_to_zero(tmp_key, MAX_SRTP_KEY_LEN); + return srtp_err_status_init_fail; + } + } + if (rtp_xtn_hdr_salt_len > 0) { + debug_print( + mod_srtp, "extensions cipher salt: %s", + srtp_octet_string_hex_string(tmp_key + rtp_xtn_hdr_base_key_len, + rtp_xtn_hdr_salt_len)); + } + + /* initialize extensions header cipher */ + stat = srtp_cipher_init(session_keys->rtp_xtn_hdr_cipher, tmp_key); + if (stat) { + /* zeroize temp buffer */ + octet_string_set_to_zero(tmp_key, MAX_SRTP_KEY_LEN); + return srtp_err_status_init_fail; + } + + if (xtn_hdr_kdf != &kdf) { + /* release memory for custom header extension encryption kdf */ + stat = srtp_kdf_clear(xtn_hdr_kdf); + if (stat) { + /* zeroize temp buffer */ + octet_string_set_to_zero(tmp_key, MAX_SRTP_KEY_LEN); + return srtp_err_status_init_fail; + } + } + } + + /* generate authentication key */ + stat = srtp_kdf_generate(&kdf, label_rtp_msg_auth, tmp_key, + srtp_auth_get_key_length(session_keys->rtp_auth)); + if (stat) { + /* zeroize temp buffer */ + octet_string_set_to_zero(tmp_key, MAX_SRTP_KEY_LEN); + return srtp_err_status_init_fail; + } + debug_print(mod_srtp, "auth key: %s", + srtp_octet_string_hex_string( + tmp_key, srtp_auth_get_key_length(session_keys->rtp_auth))); + + /* initialize auth function */ + stat = srtp_auth_init(session_keys->rtp_auth, tmp_key); + if (stat) { + /* zeroize temp buffer */ + octet_string_set_to_zero(tmp_key, MAX_SRTP_KEY_LEN); + return srtp_err_status_init_fail; + } + + /* + * ...now initialize SRTCP keys + */ + + rtcp_base_key_len = + base_key_length(session_keys->rtcp_cipher->type, rtcp_keylen); + rtcp_salt_len = rtcp_keylen - rtcp_base_key_len; + debug_print(mod_srtp, "rtcp salt len: %d", rtcp_salt_len); + + /* generate encryption key */ + stat = srtp_kdf_generate(&kdf, label_rtcp_encryption, tmp_key, + rtcp_base_key_len); + if (stat) { + /* zeroize temp buffer */ + octet_string_set_to_zero(tmp_key, MAX_SRTP_KEY_LEN); + return srtp_err_status_init_fail; + } + + /* + * if the cipher in the srtp context uses a salt, then we need + * to generate the salt value + */ + if (rtcp_salt_len > 0) { + debug_print0(mod_srtp, "found rtcp_salt_len > 0, generating rtcp salt"); + + /* generate encryption salt, put after encryption key */ + stat = srtp_kdf_generate(&kdf, label_rtcp_salt, + tmp_key + rtcp_base_key_len, rtcp_salt_len); + if (stat) { + /* zeroize temp buffer */ + octet_string_set_to_zero(tmp_key, MAX_SRTP_KEY_LEN); + return srtp_err_status_init_fail; + } + memcpy(session_keys->c_salt, tmp_key + rtcp_base_key_len, + SRTP_AEAD_SALT_LEN); + } + debug_print(mod_srtp, "rtcp cipher key: %s", + srtp_octet_string_hex_string(tmp_key, rtcp_base_key_len)); + if (rtcp_salt_len > 0) { + debug_print(mod_srtp, "rtcp cipher salt: %s", + srtp_octet_string_hex_string(tmp_key + rtcp_base_key_len, + rtcp_salt_len)); + } + + /* initialize cipher */ + stat = srtp_cipher_init(session_keys->rtcp_cipher, tmp_key); + if (stat) { + /* zeroize temp buffer */ + octet_string_set_to_zero(tmp_key, MAX_SRTP_KEY_LEN); + return srtp_err_status_init_fail; + } + + /* generate authentication key */ + stat = srtp_kdf_generate(&kdf, label_rtcp_msg_auth, tmp_key, + srtp_auth_get_key_length(session_keys->rtcp_auth)); + if (stat) { + /* zeroize temp buffer */ + octet_string_set_to_zero(tmp_key, MAX_SRTP_KEY_LEN); + return srtp_err_status_init_fail; + } + + debug_print( + mod_srtp, "rtcp auth key: %s", + srtp_octet_string_hex_string( + tmp_key, srtp_auth_get_key_length(session_keys->rtcp_auth))); + + /* initialize auth function */ + stat = srtp_auth_init(session_keys->rtcp_auth, tmp_key); + if (stat) { + /* zeroize temp buffer */ + octet_string_set_to_zero(tmp_key, MAX_SRTP_KEY_LEN); + return srtp_err_status_init_fail; + } + + /* clear memory then return */ + stat = srtp_kdf_clear(&kdf); + octet_string_set_to_zero(tmp_key, MAX_SRTP_KEY_LEN); + if (stat) + return srtp_err_status_init_fail; + + return srtp_err_status_ok; +} + +srtp_err_status_t srtp_stream_init(srtp_stream_ctx_t *srtp, + const srtp_policy_t *p) +{ + srtp_err_status_t err; + + err = srtp_valid_policy(p); + if (err != srtp_err_status_ok) { + return err; + } + + debug_print(mod_srtp, "initializing stream (SSRC: 0x%08x)", p->ssrc.value); + + /* initialize replay database */ + /* + * window size MUST be at least 64. MAY be larger. Values more than + * 2^15 aren't meaningful due to how extended sequence numbers are + * calculated. + * Let a window size of 0 imply the default value. + */ + + if (p->window_size != 0 && + (p->window_size < 64 || p->window_size >= 0x8000)) + return srtp_err_status_bad_param; + + if (p->window_size != 0) + err = srtp_rdbx_init(&srtp->rtp_rdbx, p->window_size); + else + err = srtp_rdbx_init(&srtp->rtp_rdbx, 128); + if (err) + return err; + + /* set the SSRC value */ + srtp->ssrc = htonl(p->ssrc.value); + + /* reset pending ROC */ + srtp->pending_roc = 0; + + /* set the security service flags */ + srtp->rtp_services = p->rtp.sec_serv; + srtp->rtcp_services = p->rtcp.sec_serv; + + /* + * set direction to unknown - this flag gets checked in srtp_protect(), + * srtp_unprotect(), srtp_protect_rtcp(), and srtp_unprotect_rtcp(), and + * gets set appropriately if it is set to unknown. + */ + srtp->direction = dir_unknown; + + /* initialize SRTCP replay database */ + srtp_rdb_init(&srtp->rtcp_rdb); + + /* initialize allow_repeat_tx */ + /* guard against uninitialized memory: allow only 0 or 1 here */ + if (p->allow_repeat_tx != 0 && p->allow_repeat_tx != 1) { + srtp_rdbx_dealloc(&srtp->rtp_rdbx); + return srtp_err_status_bad_param; + } + srtp->allow_repeat_tx = p->allow_repeat_tx; + + /* DAM - no RTCP key limit at present */ + + /* initialize keys */ + err = srtp_stream_init_all_master_keys(srtp, p->key, p->keys, + p->num_master_keys); + if (err) { + srtp_rdbx_dealloc(&srtp->rtp_rdbx); + return err; + } + + return srtp_err_status_ok; +} + +/* + * srtp_event_reporter is an event handler function that merely + * reports the events that are reported by the callbacks + */ + +void srtp_event_reporter(srtp_event_data_t *data) +{ + srtp_err_report(srtp_err_level_warning, "srtp: in stream 0x%x: ", + data->ssrc); + + switch (data->event) { + case event_ssrc_collision: + srtp_err_report(srtp_err_level_warning, "\tSSRC collision\n"); + break; + case event_key_soft_limit: + srtp_err_report(srtp_err_level_warning, + "\tkey usage soft limit reached\n"); + break; + case event_key_hard_limit: + srtp_err_report(srtp_err_level_warning, + "\tkey usage hard limit reached\n"); + break; + case event_packet_index_limit: + srtp_err_report(srtp_err_level_warning, + "\tpacket index limit reached\n"); + break; + default: + srtp_err_report(srtp_err_level_warning, + "\tunknown event reported to handler\n"); + } +} + +/* + * srtp_event_handler is a global variable holding a pointer to the + * event handler function; this function is called for any unexpected + * event that needs to be handled out of the SRTP data path. see + * srtp_event_t in srtp.h for more info + * + * it is okay to set srtp_event_handler to NULL, but we set + * it to the srtp_event_reporter. + */ + +static srtp_event_handler_func_t *srtp_event_handler = srtp_event_reporter; + +srtp_err_status_t srtp_install_event_handler(srtp_event_handler_func_t func) +{ + /* + * note that we accept NULL arguments intentionally - calling this + * function with a NULL arguments removes an event handler that's + * been previously installed + */ + + /* set global event handling function */ + srtp_event_handler = func; + return srtp_err_status_ok; +} + +/* + * Check if the given extension header id is / should be encrypted. + * Returns 1 if yes, otherwise 0. + */ +static int srtp_protect_extension_header(srtp_stream_ctx_t *stream, int id) +{ + int *enc_xtn_hdr = stream->enc_xtn_hdr; + int count = stream->enc_xtn_hdr_count; + + if (!enc_xtn_hdr || count <= 0) { + return 0; + } + + while (count > 0) { + if (*enc_xtn_hdr == id) { + return 1; + } + + enc_xtn_hdr++; + count--; + } + return 0; +} + +/* + * extensions header encryption RFC 6904 + */ +static srtp_err_status_t srtp_process_header_encryption( + srtp_stream_ctx_t *stream, + srtp_hdr_xtnd_t *xtn_hdr, + srtp_session_keys_t *session_keys) +{ + srtp_err_status_t status; + uint8_t keystream[257]; /* Maximum 2 bytes header + 255 bytes data. */ + int keystream_pos; + uint8_t *xtn_hdr_data = ((uint8_t *)xtn_hdr) + octets_in_rtp_extn_hdr; + uint8_t *xtn_hdr_end = + xtn_hdr_data + (ntohs(xtn_hdr->length) * sizeof(uint32_t)); + + if (ntohs(xtn_hdr->profile_specific) == 0xbede) { + /* RFC 5285, section 4.2. One-Byte Header */ + while (xtn_hdr_data < xtn_hdr_end) { + uint8_t xid = (*xtn_hdr_data & 0xf0) >> 4; + unsigned int xlen = (*xtn_hdr_data & 0x0f) + 1; + uint32_t xlen_with_header = 1 + xlen; + xtn_hdr_data++; + + if (xtn_hdr_data + xlen > xtn_hdr_end) + return srtp_err_status_parse_err; + + if (xid == 15) { + /* found header 15, stop further processing. */ + break; + } + + status = srtp_cipher_output(session_keys->rtp_xtn_hdr_cipher, + keystream, &xlen_with_header); + if (status) + return srtp_err_status_cipher_fail; + + if (srtp_protect_extension_header(stream, xid)) { + keystream_pos = 1; + while (xlen > 0) { + *xtn_hdr_data ^= keystream[keystream_pos++]; + xtn_hdr_data++; + xlen--; + } + } else { + xtn_hdr_data += xlen; + } + + /* skip padding bytes. */ + while (xtn_hdr_data < xtn_hdr_end && *xtn_hdr_data == 0) { + xtn_hdr_data++; + } + } + } else if ((ntohs(xtn_hdr->profile_specific) & 0xfff0) == 0x1000) { + /* RFC 5285, section 4.3. Two-Byte Header */ + while (xtn_hdr_data + 1 < xtn_hdr_end) { + uint8_t xid = *xtn_hdr_data; + unsigned int xlen = *(xtn_hdr_data + 1); + uint32_t xlen_with_header = 2 + xlen; + xtn_hdr_data += 2; + + if (xtn_hdr_data + xlen > xtn_hdr_end) + return srtp_err_status_parse_err; + + status = srtp_cipher_output(session_keys->rtp_xtn_hdr_cipher, + keystream, &xlen_with_header); + if (status) + return srtp_err_status_cipher_fail; + + if (xlen > 0 && srtp_protect_extension_header(stream, xid)) { + keystream_pos = 2; + while (xlen > 0) { + *xtn_hdr_data ^= keystream[keystream_pos++]; + xtn_hdr_data++; + xlen--; + } + } else { + xtn_hdr_data += xlen; + } + + /* skip padding bytes. */ + while (xtn_hdr_data < xtn_hdr_end && *xtn_hdr_data == 0) { + xtn_hdr_data++; + } + } + } else { + /* unsupported extension header format. */ + return srtp_err_status_parse_err; + } + + return srtp_err_status_ok; +} + +/* + * AEAD uses a new IV formation method. This function implements + * section 8.1. (SRTP IV Formation for AES-GCM) of RFC7714. + * The calculation is defined as, where (+) is the xor operation: + * + * + * 0 0 0 0 0 0 0 0 0 0 1 1 + * 0 1 2 3 4 5 6 7 8 9 0 1 + * +--+--+--+--+--+--+--+--+--+--+--+--+ + * |00|00| SSRC | ROC | SEQ |---+ + * +--+--+--+--+--+--+--+--+--+--+--+--+ | + * | + * +--+--+--+--+--+--+--+--+--+--+--+--+ | + * | Encryption Salt |->(+) + * +--+--+--+--+--+--+--+--+--+--+--+--+ | + * | + * +--+--+--+--+--+--+--+--+--+--+--+--+ | + * | Initialization Vector |<--+ + * +--+--+--+--+--+--+--+--+--+--+--+--+* + * + * Input: *session_keys - pointer to SRTP stream context session keys, + * used to retrieve the SALT + * *iv - Pointer to receive the calculated IV + * *seq - The ROC and SEQ value to use for the + * IV calculation. + * *hdr - The RTP header, used to get the SSRC value + * + */ + +static void srtp_calc_aead_iv(srtp_session_keys_t *session_keys, + v128_t *iv, + srtp_xtd_seq_num_t *seq, + srtp_hdr_t *hdr) +{ + v128_t in; + v128_t salt; + +#ifdef NO_64BIT_MATH + uint32_t local_roc = ((high32(*seq) << 16) | (low32(*seq) >> 16)); + uint16_t local_seq = (uint16_t)(low32(*seq)); +#else + uint32_t local_roc = (uint32_t)(*seq >> 16); + uint16_t local_seq = (uint16_t)*seq; +#endif + + memset(&in, 0, sizeof(v128_t)); + memset(&salt, 0, sizeof(v128_t)); + + in.v16[5] = htons(local_seq); + local_roc = htonl(local_roc); + memcpy(&in.v16[3], &local_roc, sizeof(local_roc)); + + /* + * Copy in the RTP SSRC value + */ + memcpy(&in.v8[2], &hdr->ssrc, 4); + debug_print(mod_srtp, "Pre-salted RTP IV = %s\n", v128_hex_string(&in)); + + /* + * Get the SALT value from the context + */ + memcpy(salt.v8, session_keys->salt, SRTP_AEAD_SALT_LEN); + debug_print(mod_srtp, "RTP SALT = %s\n", v128_hex_string(&salt)); + + /* + * Finally, apply tyhe SALT to the input + */ + v128_xor(iv, &in, &salt); +} + +srtp_session_keys_t *srtp_get_session_keys(srtp_stream_ctx_t *stream, + uint8_t *hdr, + const unsigned int *pkt_octet_len, + unsigned int *mki_size) +{ + unsigned int base_mki_start_location = *pkt_octet_len; + unsigned int mki_start_location = 0; + unsigned int tag_len = 0; + unsigned int i = 0; + + // Determine the authentication tag size + if (stream->session_keys[0].rtp_cipher->algorithm == SRTP_AES_GCM_128 || + stream->session_keys[0].rtp_cipher->algorithm == SRTP_AES_GCM_256) { + tag_len = 0; + } else { + tag_len = srtp_auth_get_tag_length(stream->session_keys[0].rtp_auth); + } + + if (tag_len > base_mki_start_location) { + *mki_size = 0; + return NULL; + } + + base_mki_start_location -= tag_len; + + for (i = 0; i < stream->num_master_keys; i++) { + if (stream->session_keys[i].mki_size != 0 && + stream->session_keys[i].mki_size <= base_mki_start_location) { + *mki_size = stream->session_keys[i].mki_size; + mki_start_location = base_mki_start_location - *mki_size; + + if (memcmp(hdr + mki_start_location, stream->session_keys[i].mki_id, + *mki_size) == 0) { + return &stream->session_keys[i]; + } + } + } + + *mki_size = 0; + return NULL; +} + +static srtp_err_status_t srtp_estimate_index(srtp_rdbx_t *rdbx, + uint32_t roc, + srtp_xtd_seq_num_t *est, + srtp_sequence_number_t seq, + int *delta) +{ +#ifdef NO_64BIT_MATH + uint32_t internal_pkt_idx_reduced; + uint32_t external_pkt_idx_reduced; + uint32_t internal_roc; + uint32_t roc_difference; +#endif + +#ifdef NO_64BIT_MATH + *est = (srtp_xtd_seq_num_t)make64(roc >> 16, (roc << 16) | seq); + *delta = low32(est) - rdbx->index; +#else + *est = (srtp_xtd_seq_num_t)(((uint64_t)roc) << 16) | seq; + *delta = (int)(*est - rdbx->index); +#endif + + if (*est > rdbx->index) { +#ifdef NO_64BIT_MATH + internal_roc = (uint32_t)(rdbx->index >> 16); + roc_difference = roc - internal_roc; + if (roc_difference > 1) { + *delta = 0; + return srtp_err_status_pkt_idx_adv; + } + + internal_pkt_idx_reduced = (uint32_t)(rdbx->index & 0xFFFF); + external_pkt_idx_reduced = (uint32_t)((roc_difference << 16) | seq); + + if (external_pkt_idx_reduced - internal_pkt_idx_reduced > + seq_num_median) { + *delta = 0; + return srtp_err_status_pkt_idx_adv; + } +#else + if (*est - rdbx->index > seq_num_median) { + *delta = 0; + return srtp_err_status_pkt_idx_adv; + } +#endif + } else if (*est < rdbx->index) { +#ifdef NO_64BIT_MATH + + internal_roc = (uint32_t)(rdbx->index >> 16); + roc_difference = internal_roc - roc; + if (roc_difference > 1) { + *delta = 0; + return srtp_err_status_pkt_idx_adv; + } + + internal_pkt_idx_reduced = + (uint32_t)((roc_difference << 16) | rdbx->index & 0xFFFF); + external_pkt_idx_reduced = (uint32_t)(seq); + + if (internal_pkt_idx_reduced - external_pkt_idx_reduced > + seq_num_median) { + *delta = 0; + return srtp_err_status_pkt_idx_old; + } +#else + if (rdbx->index - *est > seq_num_median) { + *delta = 0; + return srtp_err_status_pkt_idx_old; + } +#endif + } + + return srtp_err_status_ok; +} + +static srtp_err_status_t srtp_get_est_pkt_index(srtp_hdr_t *hdr, + srtp_stream_ctx_t *stream, + srtp_xtd_seq_num_t *est, + int *delta) +{ + srtp_err_status_t result = srtp_err_status_ok; + + if (stream->pending_roc) { + result = srtp_estimate_index(&stream->rtp_rdbx, stream->pending_roc, + est, ntohs(hdr->seq), delta); + } else { + /* estimate packet index from seq. num. in header */ + *delta = + srtp_rdbx_estimate_index(&stream->rtp_rdbx, est, ntohs(hdr->seq)); + } + +#ifdef NO_64BIT_MATH + debug_print2(mod_srtp, "estimated u_packet index: %08x%08x", high32(*est), + low32(*est)); +#else + debug_print(mod_srtp, "estimated u_packet index: %016" PRIx64, *est); +#endif + return result; +} + +/* + * This function handles outgoing SRTP packets while in AEAD mode, + * which currently supports AES-GCM encryption. All packets are + * encrypted and authenticated. + */ +static srtp_err_status_t srtp_protect_aead(srtp_ctx_t *ctx, + srtp_stream_ctx_t *stream, + void *rtp_hdr, + unsigned int *pkt_octet_len, + srtp_session_keys_t *session_keys, + unsigned int use_mki) +{ + srtp_hdr_t *hdr = (srtp_hdr_t *)rtp_hdr; + uint32_t *enc_start; /* pointer to start of encrypted portion */ + int enc_octet_len = 0; /* number of octets in encrypted portion */ + srtp_xtd_seq_num_t est; /* estimated xtd_seq_num_t of *hdr */ + int delta; /* delta of local pkt idx and that in hdr */ + srtp_err_status_t status; + uint32_t tag_len; + v128_t iv; + unsigned int aad_len; + srtp_hdr_xtnd_t *xtn_hdr = NULL; + unsigned int mki_size = 0; + uint8_t *mki_location = NULL; + + debug_print0(mod_srtp, "function srtp_protect_aead"); + + /* + * update the key usage limit, and check it to make sure that we + * didn't just hit either the soft limit or the hard limit, and call + * the event handler if we hit either. + */ + switch (srtp_key_limit_update(session_keys->limit)) { + case srtp_key_event_normal: + break; + case srtp_key_event_hard_limit: + srtp_handle_event(ctx, stream, event_key_hard_limit); + return srtp_err_status_key_expired; + case srtp_key_event_soft_limit: + default: + srtp_handle_event(ctx, stream, event_key_soft_limit); + break; + } + + /* get tag length from stream */ + tag_len = srtp_auth_get_tag_length(session_keys->rtp_auth); + + /* + * find starting point for encryption and length of data to be + * encrypted - the encrypted portion starts after the rtp header + * extension, if present; otherwise, it starts after the last csrc, + * if any are present + */ + enc_start = (uint32_t *)hdr + uint32s_in_rtp_header + hdr->cc; + if (hdr->x == 1) { + xtn_hdr = (srtp_hdr_xtnd_t *)enc_start; + enc_start += (ntohs(xtn_hdr->length) + 1); + } + /* note: the passed size is without the auth tag */ + if (!((uint8_t *)enc_start <= (uint8_t *)hdr + *pkt_octet_len)) + return srtp_err_status_parse_err; + enc_octet_len = + (int)(*pkt_octet_len - ((uint8_t *)enc_start - (uint8_t *)hdr)); + if (enc_octet_len < 0) + return srtp_err_status_parse_err; + + /* + * estimate the packet index using the start of the replay window + * and the sequence number from the header + */ + delta = srtp_rdbx_estimate_index(&stream->rtp_rdbx, &est, ntohs(hdr->seq)); + status = srtp_rdbx_check(&stream->rtp_rdbx, delta); + if (status) { + if (status != srtp_err_status_replay_fail || !stream->allow_repeat_tx) { + return status; /* we've been asked to reuse an index */ + } + } else { + srtp_rdbx_add_index(&stream->rtp_rdbx, delta); + } + +#ifdef NO_64BIT_MATH + debug_print2(mod_srtp, "estimated packet index: %08x%08x", high32(est), + low32(est)); +#else + debug_print(mod_srtp, "estimated packet index: %016" PRIx64, est); +#endif + + /* + * AEAD uses a new IV formation method + */ + srtp_calc_aead_iv(session_keys, &iv, &est, hdr); +/* shift est, put into network byte order */ +#ifdef NO_64BIT_MATH + est = be64_to_cpu( + make64((high32(est) << 16) | (low32(est) >> 16), low32(est) << 16)); +#else + est = be64_to_cpu(est << 16); +#endif + + status = srtp_cipher_set_iv(session_keys->rtp_cipher, (uint8_t *)&iv, + srtp_direction_encrypt); + if (!status && session_keys->rtp_xtn_hdr_cipher) { + iv.v32[0] = 0; + iv.v32[1] = hdr->ssrc; + iv.v64[1] = est; + status = srtp_cipher_set_iv(session_keys->rtp_xtn_hdr_cipher, + (uint8_t *)&iv, srtp_direction_encrypt); + } + if (status) { + return srtp_err_status_cipher_fail; + } + + if (xtn_hdr && session_keys->rtp_xtn_hdr_cipher) { + /* + * extensions header encryption RFC 6904 + */ + status = srtp_process_header_encryption(stream, xtn_hdr, session_keys); + if (status) { + return status; + } + } + + /* + * Set the AAD over the RTP header + */ + aad_len = (uint8_t *)enc_start - (uint8_t *)hdr; + status = + srtp_cipher_set_aad(session_keys->rtp_cipher, (uint8_t *)hdr, aad_len); + if (status) { + return (srtp_err_status_cipher_fail); + } + + /* Encrypt the payload */ + status = srtp_cipher_encrypt(session_keys->rtp_cipher, (uint8_t *)enc_start, + (unsigned int *)&enc_octet_len); + if (status) { + return srtp_err_status_cipher_fail; + } + /* + * If we're doing GCM, we need to get the tag + * and append that to the output + */ + status = + srtp_cipher_get_tag(session_keys->rtp_cipher, + (uint8_t *)enc_start + enc_octet_len, &tag_len); + if (status) { + return (srtp_err_status_cipher_fail); + } + + mki_location = (uint8_t *)hdr + *pkt_octet_len + tag_len; + mki_size = srtp_inject_mki(mki_location, session_keys, use_mki); + + /* increase the packet length by the length of the auth tag */ + *pkt_octet_len += tag_len; + + /* increase the packet length by the length of the mki_size */ + *pkt_octet_len += mki_size; + + return srtp_err_status_ok; +} + +/* + * This function handles incoming SRTP packets while in AEAD mode, + * which currently supports AES-GCM encryption. All packets are + * encrypted and authenticated. Note, the auth tag is at the end + * of the packet stream and is automatically checked by GCM + * when decrypting the payload. + */ +static srtp_err_status_t srtp_unprotect_aead(srtp_ctx_t *ctx, + srtp_stream_ctx_t *stream, + int delta, + srtp_xtd_seq_num_t est, + void *srtp_hdr, + unsigned int *pkt_octet_len, + srtp_session_keys_t *session_keys, + unsigned int mki_size) +{ + srtp_hdr_t *hdr = (srtp_hdr_t *)srtp_hdr; + uint32_t *enc_start; /* pointer to start of encrypted portion */ + unsigned int enc_octet_len = 0; /* number of octets in encrypted portion */ + v128_t iv; + srtp_err_status_t status; + int tag_len; + unsigned int aad_len; + srtp_hdr_xtnd_t *xtn_hdr = NULL; + + debug_print0(mod_srtp, "function srtp_unprotect_aead"); + +#ifdef NO_64BIT_MATH + debug_print2(mod_srtp, "estimated u_packet index: %08x%08x", high32(est), + low32(est)); +#else + debug_print(mod_srtp, "estimated u_packet index: %016" PRIx64, est); +#endif + + /* get tag length from stream */ + tag_len = srtp_auth_get_tag_length(session_keys->rtp_auth); + + /* + * AEAD uses a new IV formation method + */ + srtp_calc_aead_iv(session_keys, &iv, &est, hdr); + status = srtp_cipher_set_iv(session_keys->rtp_cipher, (uint8_t *)&iv, + srtp_direction_decrypt); + if (!status && session_keys->rtp_xtn_hdr_cipher) { + iv.v32[0] = 0; + iv.v32[1] = hdr->ssrc; +#ifdef NO_64BIT_MATH + iv.v64[1] = be64_to_cpu( + make64((high32(est) << 16) | (low32(est) >> 16), low32(est) << 16)); +#else + iv.v64[1] = be64_to_cpu(est << 16); +#endif + status = srtp_cipher_set_iv(session_keys->rtp_xtn_hdr_cipher, + (uint8_t *)&iv, srtp_direction_encrypt); + } + if (status) { + return srtp_err_status_cipher_fail; + } + + /* + * find starting point for decryption and length of data to be + * decrypted - the encrypted portion starts after the rtp header + * extension, if present; otherwise, it starts after the last csrc, + * if any are present + */ + enc_start = (uint32_t *)hdr + uint32s_in_rtp_header + hdr->cc; + if (hdr->x == 1) { + xtn_hdr = (srtp_hdr_xtnd_t *)enc_start; + enc_start += (ntohs(xtn_hdr->length) + 1); + } + if (!((uint8_t *)enc_start <= + (uint8_t *)hdr + (*pkt_octet_len - tag_len - mki_size))) + return srtp_err_status_parse_err; + /* + * We pass the tag down to the cipher when doing GCM mode + */ + enc_octet_len = (unsigned int)(*pkt_octet_len - mki_size - + ((uint8_t *)enc_start - (uint8_t *)hdr)); + + /* + * Sanity check the encrypted payload length against + * the tag size. It must always be at least as large + * as the tag length. + */ + if (enc_octet_len < (unsigned int)tag_len) { + return srtp_err_status_cipher_fail; + } + + /* + * update the key usage limit, and check it to make sure that we + * didn't just hit either the soft limit or the hard limit, and call + * the event handler if we hit either. + */ + switch (srtp_key_limit_update(session_keys->limit)) { + case srtp_key_event_normal: + break; + case srtp_key_event_soft_limit: + srtp_handle_event(ctx, stream, event_key_soft_limit); + break; + case srtp_key_event_hard_limit: + srtp_handle_event(ctx, stream, event_key_hard_limit); + return srtp_err_status_key_expired; + default: + break; + } + + /* + * Set the AAD for AES-GCM, which is the RTP header + */ + aad_len = (uint8_t *)enc_start - (uint8_t *)hdr; + status = + srtp_cipher_set_aad(session_keys->rtp_cipher, (uint8_t *)hdr, aad_len); + if (status) { + return (srtp_err_status_cipher_fail); + } + + /* Decrypt the ciphertext. This also checks the auth tag based + * on the AAD we just specified above */ + status = srtp_cipher_decrypt(session_keys->rtp_cipher, (uint8_t *)enc_start, + &enc_octet_len); + if (status) { + return status; + } + + if (xtn_hdr && session_keys->rtp_xtn_hdr_cipher) { + /* + * extensions header encryption RFC 6904 + */ + status = srtp_process_header_encryption(stream, xtn_hdr, session_keys); + if (status) { + return status; + } + } + + /* + * verify that stream is for received traffic - this check will + * detect SSRC collisions, since a stream that appears in both + * srtp_protect() and srtp_unprotect() will fail this test in one of + * those functions. + * + * we do this check *after* the authentication check, so that the + * latter check will catch any attempts to fool us into thinking + * that we've got a collision + */ + if (stream->direction != dir_srtp_receiver) { + if (stream->direction == dir_unknown) { + stream->direction = dir_srtp_receiver; + } else { + srtp_handle_event(ctx, stream, event_ssrc_collision); + } + } + + /* + * if the stream is a 'provisional' one, in which the template context + * is used, then we need to allocate a new stream at this point, since + * the authentication passed + */ + if (stream == ctx->stream_template) { + srtp_stream_ctx_t *new_stream; + + /* + * allocate and initialize a new stream + * + * note that we indicate failure if we can't allocate the new + * stream, and some implementations will want to not return + * failure here + */ + status = + srtp_stream_clone(ctx->stream_template, hdr->ssrc, &new_stream); + if (status) { + return status; + } + + /* add new stream to the head of the stream_list */ + new_stream->next = ctx->stream_list; + ctx->stream_list = new_stream; + + /* set stream (the pointer used in this function) */ + stream = new_stream; + } + + /* + * the message authentication function passed, so add the packet + * index into the replay database + */ + srtp_rdbx_add_index(&stream->rtp_rdbx, delta); + + /* decrease the packet length by the length of the auth tag */ + *pkt_octet_len -= tag_len; + + /* decrease the packet length by the length of the mki_size */ + *pkt_octet_len -= mki_size; + + return srtp_err_status_ok; +} + +srtp_err_status_t srtp_protect(srtp_ctx_t *ctx, + void *rtp_hdr, + int *pkt_octet_len) +{ + return srtp_protect_mki(ctx, rtp_hdr, pkt_octet_len, 0, 0); +} + +srtp_err_status_t srtp_protect_mki(srtp_ctx_t *ctx, + void *rtp_hdr, + int *pkt_octet_len, + unsigned int use_mki, + unsigned int mki_index) +{ + srtp_hdr_t *hdr = (srtp_hdr_t *)rtp_hdr; + uint32_t *enc_start; /* pointer to start of encrypted portion */ + uint32_t *auth_start; /* pointer to start of auth. portion */ + int enc_octet_len = 0; /* number of octets in encrypted portion */ + srtp_xtd_seq_num_t est; /* estimated xtd_seq_num_t of *hdr */ + int delta; /* delta of local pkt idx and that in hdr */ + uint8_t *auth_tag = NULL; /* location of auth_tag within packet */ + srtp_err_status_t status; + int tag_len; + srtp_stream_ctx_t *stream; + uint32_t prefix_len; + srtp_hdr_xtnd_t *xtn_hdr = NULL; + unsigned int mki_size = 0; + srtp_session_keys_t *session_keys = NULL; + uint8_t *mki_location = NULL; + int advance_packet_index = 0; + + debug_print0(mod_srtp, "function srtp_protect"); + + /* we assume the hdr is 32-bit aligned to start */ + + /* Verify RTP header */ + status = srtp_validate_rtp_header(rtp_hdr, pkt_octet_len); + if (status) + return status; + + /* check the packet length - it must at least contain a full header */ + if (*pkt_octet_len < octets_in_rtp_header) + return srtp_err_status_bad_param; + + /* + * look up ssrc in srtp_stream list, and process the packet with + * the appropriate stream. if we haven't seen this stream before, + * there's a template key for this srtp_session, and the cipher + * supports key-sharing, then we assume that a new stream using + * that key has just started up + */ + stream = srtp_get_stream(ctx, hdr->ssrc); + if (stream == NULL) { + if (ctx->stream_template != NULL) { + srtp_stream_ctx_t *new_stream; + + /* allocate and initialize a new stream */ + status = + srtp_stream_clone(ctx->stream_template, hdr->ssrc, &new_stream); + if (status) + return status; + + /* add new stream to the head of the stream_list */ + new_stream->next = ctx->stream_list; + ctx->stream_list = new_stream; + + /* set direction to outbound */ + new_stream->direction = dir_srtp_sender; + + /* set stream (the pointer used in this function) */ + stream = new_stream; + } else { + /* no template stream, so we return an error */ + return srtp_err_status_no_ctx; + } + } + + /* + * verify that stream is for sending traffic - this check will + * detect SSRC collisions, since a stream that appears in both + * srtp_protect() and srtp_unprotect() will fail this test in one of + * those functions. + */ + + if (stream->direction != dir_srtp_sender) { + if (stream->direction == dir_unknown) { + stream->direction = dir_srtp_sender; + } else { + srtp_handle_event(ctx, stream, event_ssrc_collision); + } + } + + session_keys = + srtp_get_session_keys_with_mki_index(stream, use_mki, mki_index); + + if (session_keys == NULL) + return srtp_err_status_bad_mki; + + /* + * Check if this is an AEAD stream (GCM mode). If so, then dispatch + * the request to our AEAD handler. + */ + if (session_keys->rtp_cipher->algorithm == SRTP_AES_GCM_128 || + session_keys->rtp_cipher->algorithm == SRTP_AES_GCM_256) { + return srtp_protect_aead(ctx, stream, rtp_hdr, + (unsigned int *)pkt_octet_len, session_keys, + use_mki); + } + + /* + * update the key usage limit, and check it to make sure that we + * didn't just hit either the soft limit or the hard limit, and call + * the event handler if we hit either. + */ + switch (srtp_key_limit_update(session_keys->limit)) { + case srtp_key_event_normal: + break; + case srtp_key_event_soft_limit: + srtp_handle_event(ctx, stream, event_key_soft_limit); + break; + case srtp_key_event_hard_limit: + srtp_handle_event(ctx, stream, event_key_hard_limit); + return srtp_err_status_key_expired; + default: + break; + } + + /* get tag length from stream */ + tag_len = srtp_auth_get_tag_length(session_keys->rtp_auth); + + /* + * find starting point for encryption and length of data to be + * encrypted - the encrypted portion starts after the rtp header + * extension, if present; otherwise, it starts after the last csrc, + * if any are present + * + * if we're not providing confidentiality, set enc_start to NULL + */ + if (stream->rtp_services & sec_serv_conf) { + enc_start = (uint32_t *)hdr + uint32s_in_rtp_header + hdr->cc; + if (hdr->x == 1) { + xtn_hdr = (srtp_hdr_xtnd_t *)enc_start; + enc_start += (ntohs(xtn_hdr->length) + 1); + } + /* note: the passed size is without the auth tag */ + if (!((uint8_t *)enc_start <= (uint8_t *)hdr + *pkt_octet_len)) + return srtp_err_status_parse_err; + enc_octet_len = + (int)(*pkt_octet_len - ((uint8_t *)enc_start - (uint8_t *)hdr)); + if (enc_octet_len < 0) + return srtp_err_status_parse_err; + } else { + enc_start = NULL; + } + + mki_location = (uint8_t *)hdr + *pkt_octet_len; + mki_size = srtp_inject_mki(mki_location, session_keys, use_mki); + + /* + * if we're providing authentication, set the auth_start and auth_tag + * pointers to the proper locations; otherwise, set auth_start to NULL + * to indicate that no authentication is needed + */ + if (stream->rtp_services & sec_serv_auth) { + auth_start = (uint32_t *)hdr; + auth_tag = (uint8_t *)hdr + *pkt_octet_len + mki_size; + } else { + auth_start = NULL; + auth_tag = NULL; + } + + /* + * estimate the packet index using the start of the replay window + * and the sequence number from the header + */ + status = srtp_get_est_pkt_index(hdr, stream, &est, &delta); + + if (status && (status != srtp_err_status_pkt_idx_adv)) + return status; + + if (status == srtp_err_status_pkt_idx_adv) + advance_packet_index = 1; + + if (advance_packet_index) { + srtp_rdbx_set_roc_seq(&stream->rtp_rdbx, (uint32_t)(est >> 16), + (uint16_t)(est & 0xFFFF)); + stream->pending_roc = 0; + srtp_rdbx_add_index(&stream->rtp_rdbx, 0); + } else { + status = srtp_rdbx_check(&stream->rtp_rdbx, delta); + if (status) { + if (status != srtp_err_status_replay_fail || + !stream->allow_repeat_tx) + return status; /* we've been asked to reuse an index */ + } + srtp_rdbx_add_index(&stream->rtp_rdbx, delta); + } + +#ifdef NO_64BIT_MATH + debug_print2(mod_srtp, "estimated packet index: %08x%08x", high32(est), + low32(est)); +#else + debug_print(mod_srtp, "estimated packet index: %016" PRIx64, est); +#endif + + /* + * if we're using rindael counter mode, set nonce and seq + */ + if (session_keys->rtp_cipher->type->id == SRTP_AES_ICM_128 || + session_keys->rtp_cipher->type->id == SRTP_AES_ICM_192 || + session_keys->rtp_cipher->type->id == SRTP_AES_ICM_256) { + v128_t iv; + + iv.v32[0] = 0; + iv.v32[1] = hdr->ssrc; +#ifdef NO_64BIT_MATH + iv.v64[1] = be64_to_cpu( + make64((high32(est) << 16) | (low32(est) >> 16), low32(est) << 16)); +#else + iv.v64[1] = be64_to_cpu(est << 16); +#endif + status = srtp_cipher_set_iv(session_keys->rtp_cipher, (uint8_t *)&iv, + srtp_direction_encrypt); + if (!status && session_keys->rtp_xtn_hdr_cipher) { + status = srtp_cipher_set_iv(session_keys->rtp_xtn_hdr_cipher, + (uint8_t *)&iv, srtp_direction_encrypt); + } + } else { + v128_t iv; + +/* otherwise, set the index to est */ +#ifdef NO_64BIT_MATH + iv.v32[0] = 0; + iv.v32[1] = 0; +#else + iv.v64[0] = 0; +#endif + iv.v64[1] = be64_to_cpu(est); + status = srtp_cipher_set_iv(session_keys->rtp_cipher, (uint8_t *)&iv, + srtp_direction_encrypt); + if (!status && session_keys->rtp_xtn_hdr_cipher) { + status = srtp_cipher_set_iv(session_keys->rtp_xtn_hdr_cipher, + (uint8_t *)&iv, srtp_direction_encrypt); + } + } + if (status) + return srtp_err_status_cipher_fail; + +/* shift est, put into network byte order */ +#ifdef NO_64BIT_MATH + est = be64_to_cpu( + make64((high32(est) << 16) | (low32(est) >> 16), low32(est) << 16)); +#else + est = be64_to_cpu(est << 16); +#endif + + /* + * if we're authenticating using a universal hash, put the keystream + * prefix into the authentication tag + */ + if (auth_start) { + prefix_len = srtp_auth_get_prefix_length(session_keys->rtp_auth); + if (prefix_len) { + status = srtp_cipher_output(session_keys->rtp_cipher, auth_tag, + &prefix_len); + if (status) + return srtp_err_status_cipher_fail; + debug_print(mod_srtp, "keystream prefix: %s", + srtp_octet_string_hex_string(auth_tag, prefix_len)); + } + } + + if (xtn_hdr && session_keys->rtp_xtn_hdr_cipher) { + /* + * extensions header encryption RFC 6904 + */ + status = srtp_process_header_encryption(stream, xtn_hdr, session_keys); + if (status) { + return status; + } + } + + /* if we're encrypting, exor keystream into the message */ + if (enc_start) { + status = + srtp_cipher_encrypt(session_keys->rtp_cipher, (uint8_t *)enc_start, + (unsigned int *)&enc_octet_len); + if (status) + return srtp_err_status_cipher_fail; + } + + /* + * if we're authenticating, run authentication function and put result + * into the auth_tag + */ + if (auth_start) { + /* initialize auth func context */ + status = srtp_auth_start(session_keys->rtp_auth); + if (status) + return status; + + /* run auth func over packet */ + status = srtp_auth_update(session_keys->rtp_auth, (uint8_t *)auth_start, + *pkt_octet_len); + if (status) + return status; + + /* run auth func over ROC, put result into auth_tag */ + debug_print(mod_srtp, "estimated packet index: %016" PRIx64, est); + status = srtp_auth_compute(session_keys->rtp_auth, (uint8_t *)&est, 4, + auth_tag); + debug_print(mod_srtp, "srtp auth tag: %s", + srtp_octet_string_hex_string(auth_tag, tag_len)); + if (status) + return srtp_err_status_auth_fail; + } + + if (auth_tag) { + /* increase the packet length by the length of the auth tag */ + *pkt_octet_len += tag_len; + } + + if (use_mki) { + /* increate the packet length by the mki size */ + *pkt_octet_len += mki_size; + } + + return srtp_err_status_ok; +} + +srtp_err_status_t srtp_unprotect(srtp_ctx_t *ctx, + void *srtp_hdr, + int *pkt_octet_len) +{ + return srtp_unprotect_mki(ctx, srtp_hdr, pkt_octet_len, 0); +} + +srtp_err_status_t srtp_unprotect_mki(srtp_ctx_t *ctx, + void *srtp_hdr, + int *pkt_octet_len, + unsigned int use_mki) +{ + srtp_hdr_t *hdr = (srtp_hdr_t *)srtp_hdr; + uint32_t *enc_start; /* pointer to start of encrypted portion */ + uint32_t *auth_start; /* pointer to start of auth. portion */ + unsigned int enc_octet_len = 0; /* number of octets in encrypted portion */ + uint8_t *auth_tag = NULL; /* location of auth_tag within packet */ + srtp_xtd_seq_num_t est; /* estimated xtd_seq_num_t of *hdr */ + int delta; /* delta of local pkt idx and that in hdr */ + v128_t iv; + srtp_err_status_t status; + srtp_stream_ctx_t *stream; + uint8_t tmp_tag[SRTP_MAX_TAG_LEN]; + uint32_t tag_len, prefix_len; + srtp_hdr_xtnd_t *xtn_hdr = NULL; + unsigned int mki_size = 0; + srtp_session_keys_t *session_keys = NULL; + int advance_packet_index = 0; + uint32_t roc_to_set = 0; + uint16_t seq_to_set = 0; + + debug_print0(mod_srtp, "function srtp_unprotect"); + + /* we assume the hdr is 32-bit aligned to start */ + + /* Verify RTP header */ + status = srtp_validate_rtp_header(srtp_hdr, pkt_octet_len); + if (status) + return status; + + /* check the packet length - it must at least contain a full header */ + if (*pkt_octet_len < octets_in_rtp_header) + return srtp_err_status_bad_param; + + /* + * look up ssrc in srtp_stream list, and process the packet with + * the appropriate stream. if we haven't seen this stream before, + * there's only one key for this srtp_session, and the cipher + * supports key-sharing, then we assume that a new stream using + * that key has just started up + */ + stream = srtp_get_stream(ctx, hdr->ssrc); + if (stream == NULL) { + if (ctx->stream_template != NULL) { + stream = ctx->stream_template; + debug_print(mod_srtp, "using provisional stream (SSRC: 0x%08x)", + ntohl(hdr->ssrc)); + +/* + * set estimated packet index to sequence number from header, + * and set delta equal to the same value + */ +#ifdef NO_64BIT_MATH + est = (srtp_xtd_seq_num_t)make64(0, ntohs(hdr->seq)); + delta = low32(est); +#else + est = (srtp_xtd_seq_num_t)ntohs(hdr->seq); + delta = (int)est; +#endif + } else { + /* + * no stream corresponding to SSRC found, and we don't do + * key-sharing, so return an error + */ + return srtp_err_status_no_ctx; + } + } else { + status = srtp_get_est_pkt_index(hdr, stream, &est, &delta); + + if (status && (status != srtp_err_status_pkt_idx_adv)) + return status; + + if (status == srtp_err_status_pkt_idx_adv) { + advance_packet_index = 1; + roc_to_set = (uint32_t)(est >> 16); + seq_to_set = (uint16_t)(est & 0xFFFF); + } + + /* check replay database */ + if (!advance_packet_index) { + status = srtp_rdbx_check(&stream->rtp_rdbx, delta); + if (status) + return status; + } + } + +#ifdef NO_64BIT_MATH + debug_print2(mod_srtp, "estimated u_packet index: %08x%08x", high32(est), + low32(est)); +#else + debug_print(mod_srtp, "estimated u_packet index: %016" PRIx64, est); +#endif + + /* Determine if MKI is being used and what session keys should be used */ + if (use_mki) { + session_keys = srtp_get_session_keys( + stream, (uint8_t *)hdr, (const unsigned int *)pkt_octet_len, + &mki_size); + + if (session_keys == NULL) + return srtp_err_status_bad_mki; + } else { + session_keys = &stream->session_keys[0]; + } + + /* + * Check if this is an AEAD stream (GCM mode). If so, then dispatch + * the request to our AEAD handler. + */ + if (session_keys->rtp_cipher->algorithm == SRTP_AES_GCM_128 || + session_keys->rtp_cipher->algorithm == SRTP_AES_GCM_256) { + return srtp_unprotect_aead(ctx, stream, delta, est, srtp_hdr, + (unsigned int *)pkt_octet_len, session_keys, + mki_size); + } + + /* get tag length from stream */ + tag_len = srtp_auth_get_tag_length(session_keys->rtp_auth); + + /* + * set the cipher's IV properly, depending on whatever cipher we + * happen to be using + */ + if (session_keys->rtp_cipher->type->id == SRTP_AES_ICM_128 || + session_keys->rtp_cipher->type->id == SRTP_AES_ICM_192 || + session_keys->rtp_cipher->type->id == SRTP_AES_ICM_256) { + /* aes counter mode */ + iv.v32[0] = 0; + iv.v32[1] = hdr->ssrc; /* still in network order */ +#ifdef NO_64BIT_MATH + iv.v64[1] = be64_to_cpu( + make64((high32(est) << 16) | (low32(est) >> 16), low32(est) << 16)); +#else + iv.v64[1] = be64_to_cpu(est << 16); +#endif + status = srtp_cipher_set_iv(session_keys->rtp_cipher, (uint8_t *)&iv, + srtp_direction_decrypt); + if (!status && session_keys->rtp_xtn_hdr_cipher) { + status = srtp_cipher_set_iv(session_keys->rtp_xtn_hdr_cipher, + (uint8_t *)&iv, srtp_direction_decrypt); + } + } else { +/* no particular format - set the iv to the pakcet index */ +#ifdef NO_64BIT_MATH + iv.v32[0] = 0; + iv.v32[1] = 0; +#else + iv.v64[0] = 0; +#endif + iv.v64[1] = be64_to_cpu(est); + status = srtp_cipher_set_iv(session_keys->rtp_cipher, (uint8_t *)&iv, + srtp_direction_decrypt); + if (!status && session_keys->rtp_xtn_hdr_cipher) { + status = srtp_cipher_set_iv(session_keys->rtp_xtn_hdr_cipher, + (uint8_t *)&iv, srtp_direction_decrypt); + } + } + if (status) + return srtp_err_status_cipher_fail; + +/* shift est, put into network byte order */ +#ifdef NO_64BIT_MATH + est = be64_to_cpu( + make64((high32(est) << 16) | (low32(est) >> 16), low32(est) << 16)); +#else + est = be64_to_cpu(est << 16); +#endif + + /* + * find starting point for decryption and length of data to be + * decrypted - the encrypted portion starts after the rtp header + * extension, if present; otherwise, it starts after the last csrc, + * if any are present + * + * if we're not providing confidentiality, set enc_start to NULL + */ + if (stream->rtp_services & sec_serv_conf) { + enc_start = (uint32_t *)hdr + uint32s_in_rtp_header + hdr->cc; + if (hdr->x == 1) { + xtn_hdr = (srtp_hdr_xtnd_t *)enc_start; + enc_start += (ntohs(xtn_hdr->length) + 1); + } + if (!((uint8_t *)enc_start <= + (uint8_t *)hdr + (*pkt_octet_len - tag_len - mki_size))) + return srtp_err_status_parse_err; + enc_octet_len = (uint32_t)(*pkt_octet_len - tag_len - mki_size - + ((uint8_t *)enc_start - (uint8_t *)hdr)); + } else { + enc_start = NULL; + } + + /* + * if we're providing authentication, set the auth_start and auth_tag + * pointers to the proper locations; otherwise, set auth_start to NULL + * to indicate that no authentication is needed + */ + if (stream->rtp_services & sec_serv_auth) { + auth_start = (uint32_t *)hdr; + auth_tag = (uint8_t *)hdr + *pkt_octet_len - tag_len; + } else { + auth_start = NULL; + auth_tag = NULL; + } + + /* + * if we expect message authentication, run the authentication + * function and compare the result with the value of the auth_tag + */ + if (auth_start) { + /* + * if we're using a universal hash, then we need to compute the + * keystream prefix for encrypting the universal hash output + * + * if the keystream prefix length is zero, then we know that + * the authenticator isn't using a universal hash function + */ + if (session_keys->rtp_auth->prefix_len != 0) { + prefix_len = srtp_auth_get_prefix_length(session_keys->rtp_auth); + status = srtp_cipher_output(session_keys->rtp_cipher, tmp_tag, + &prefix_len); + debug_print(mod_srtp, "keystream prefix: %s", + srtp_octet_string_hex_string(tmp_tag, prefix_len)); + if (status) + return srtp_err_status_cipher_fail; + } + + /* initialize auth func context */ + status = srtp_auth_start(session_keys->rtp_auth); + if (status) + return status; + + /* now compute auth function over packet */ + status = srtp_auth_update(session_keys->rtp_auth, (uint8_t *)auth_start, + *pkt_octet_len - tag_len - mki_size); + if (status) + return status; + + /* run auth func over ROC, then write tmp tag */ + status = srtp_auth_compute(session_keys->rtp_auth, (uint8_t *)&est, 4, + tmp_tag); + + debug_print(mod_srtp, "computed auth tag: %s", + srtp_octet_string_hex_string(tmp_tag, tag_len)); + debug_print(mod_srtp, "packet auth tag: %s", + srtp_octet_string_hex_string(auth_tag, tag_len)); + if (status) + return srtp_err_status_auth_fail; + + if (srtp_octet_string_is_eq(tmp_tag, auth_tag, tag_len)) + return srtp_err_status_auth_fail; + } + + /* + * update the key usage limit, and check it to make sure that we + * didn't just hit either the soft limit or the hard limit, and call + * the event handler if we hit either. + */ + switch (srtp_key_limit_update(session_keys->limit)) { + case srtp_key_event_normal: + break; + case srtp_key_event_soft_limit: + srtp_handle_event(ctx, stream, event_key_soft_limit); + break; + case srtp_key_event_hard_limit: + srtp_handle_event(ctx, stream, event_key_hard_limit); + return srtp_err_status_key_expired; + default: + break; + } + + if (xtn_hdr && session_keys->rtp_xtn_hdr_cipher) { + /* extensions header encryption RFC 6904 */ + status = srtp_process_header_encryption(stream, xtn_hdr, session_keys); + if (status) { + return status; + } + } + + /* if we're decrypting, add keystream into ciphertext */ + if (enc_start) { + status = srtp_cipher_decrypt(session_keys->rtp_cipher, + (uint8_t *)enc_start, &enc_octet_len); + if (status) + return srtp_err_status_cipher_fail; + } + + /* + * verify that stream is for received traffic - this check will + * detect SSRC collisions, since a stream that appears in both + * srtp_protect() and srtp_unprotect() will fail this test in one of + * those functions. + * + * we do this check *after* the authentication check, so that the + * latter check will catch any attempts to fool us into thinking + * that we've got a collision + */ + if (stream->direction != dir_srtp_receiver) { + if (stream->direction == dir_unknown) { + stream->direction = dir_srtp_receiver; + } else { + srtp_handle_event(ctx, stream, event_ssrc_collision); + } + } + + /* + * if the stream is a 'provisional' one, in which the template context + * is used, then we need to allocate a new stream at this point, since + * the authentication passed + */ + if (stream == ctx->stream_template) { + srtp_stream_ctx_t *new_stream; + + /* + * allocate and initialize a new stream + * + * note that we indicate failure if we can't allocate the new + * stream, and some implementations will want to not return + * failure here + */ + status = + srtp_stream_clone(ctx->stream_template, hdr->ssrc, &new_stream); + if (status) + return status; + + /* add new stream to the head of the stream_list */ + new_stream->next = ctx->stream_list; + ctx->stream_list = new_stream; + + /* set stream (the pointer used in this function) */ + stream = new_stream; + } + + /* + * the message authentication function passed, so add the packet + * index into the replay database + */ + if (advance_packet_index) { + srtp_rdbx_set_roc_seq(&stream->rtp_rdbx, roc_to_set, seq_to_set); + stream->pending_roc = 0; + srtp_rdbx_add_index(&stream->rtp_rdbx, 0); + } else { + srtp_rdbx_add_index(&stream->rtp_rdbx, delta); + } + + /* decrease the packet length by the length of the auth tag */ + *pkt_octet_len -= tag_len; + + /* decrease the packet length by the mki size */ + *pkt_octet_len -= mki_size; + + return srtp_err_status_ok; +} + +srtp_err_status_t srtp_init() +{ + srtp_err_status_t status; + + /* initialize crypto kernel */ + status = srtp_crypto_kernel_init(); + if (status) + return status; + + /* load srtp debug module into the kernel */ + status = srtp_crypto_kernel_load_debug_module(&mod_srtp); + if (status) + return status; + + return srtp_err_status_ok; +} + +srtp_err_status_t srtp_shutdown() +{ + srtp_err_status_t status; + + /* shut down crypto kernel */ + status = srtp_crypto_kernel_shutdown(); + if (status) + return status; + + /* shutting down crypto kernel frees the srtp debug module as well */ + + return srtp_err_status_ok; +} + +/* + * srtp_get_stream(ssrc) returns a pointer to the stream corresponding + * to ssrc, or NULL if no stream exists for that ssrc + * + * this is an internal function + */ + +srtp_stream_ctx_t *srtp_get_stream(srtp_t srtp, uint32_t ssrc) +{ + srtp_stream_ctx_t *stream; + + /* walk down list until ssrc is found */ + stream = srtp->stream_list; + while (stream != NULL) { + if (stream->ssrc == ssrc) + return stream; + stream = stream->next; + } + + /* we haven't found our ssrc, so return a null */ + return NULL; +} + +srtp_err_status_t srtp_dealloc(srtp_t session) +{ + srtp_stream_ctx_t *stream; + srtp_err_status_t status; + + /* + * we take a conservative deallocation strategy - if we encounter an + * error deallocating a stream, then we stop trying to deallocate + * memory and just return an error + */ + + /* walk list of streams, deallocating as we go */ + stream = session->stream_list; + while (stream != NULL) { + srtp_stream_t next = stream->next; + status = srtp_stream_dealloc(stream, session->stream_template); + if (status) + return status; + stream = next; + } + + /* deallocate stream template, if there is one */ + if (session->stream_template != NULL) { + status = srtp_stream_dealloc(session->stream_template, NULL); + if (status) + return status; + } + + /* deallocate session context */ + srtp_crypto_free(session); + + return srtp_err_status_ok; +} + +srtp_err_status_t srtp_add_stream(srtp_t session, const srtp_policy_t *policy) +{ + srtp_err_status_t status; + srtp_stream_t tmp; + + status = srtp_valid_policy(policy); + if (status != srtp_err_status_ok) { + return status; + } + + /* sanity check arguments */ + if ((session == NULL) || (policy == NULL) || + (!srtp_validate_policy_master_keys(policy))) + return srtp_err_status_bad_param; + + /* allocate stream */ + status = srtp_stream_alloc(&tmp, policy); + if (status) { + return status; + } + + /* initialize stream */ + status = srtp_stream_init(tmp, policy); + if (status) { + srtp_stream_dealloc(tmp, NULL); + return status; + } + + /* + * set the head of the stream list or the template to point to the + * stream that we've just alloced and init'ed, depending on whether + * or not it has a wildcard SSRC value or not + * + * if the template stream has already been set, then the policy is + * inconsistent, so we return a bad_param error code + */ + switch (policy->ssrc.type) { + case (ssrc_any_outbound): + if (session->stream_template) { + srtp_stream_dealloc(tmp, NULL); + return srtp_err_status_bad_param; + } + session->stream_template = tmp; + session->stream_template->direction = dir_srtp_sender; + break; + case (ssrc_any_inbound): + if (session->stream_template) { + srtp_stream_dealloc(tmp, NULL); + return srtp_err_status_bad_param; + } + session->stream_template = tmp; + session->stream_template->direction = dir_srtp_receiver; + break; + case (ssrc_specific): + tmp->next = session->stream_list; + session->stream_list = tmp; + break; + case (ssrc_undefined): + default: + srtp_stream_dealloc(tmp, NULL); + return srtp_err_status_bad_param; + } + + return srtp_err_status_ok; +} + +srtp_err_status_t srtp_create(srtp_t *session, /* handle for session */ + const srtp_policy_t *policy) +{ /* SRTP policy (list) */ + srtp_err_status_t stat; + srtp_ctx_t *ctx; + + stat = srtp_valid_policy(policy); + if (stat != srtp_err_status_ok) { + return stat; + } + + /* sanity check arguments */ + if (session == NULL) + return srtp_err_status_bad_param; + + /* allocate srtp context and set ctx_ptr */ + ctx = (srtp_ctx_t *)srtp_crypto_alloc(sizeof(srtp_ctx_t)); + if (ctx == NULL) + return srtp_err_status_alloc_fail; + *session = ctx; + + /* + * loop over elements in the policy list, allocating and + * initializing a stream for each element + */ + ctx->stream_template = NULL; + ctx->stream_list = NULL; + ctx->user_data = NULL; + while (policy != NULL) { + stat = srtp_add_stream(ctx, policy); + if (stat) { + /* clean up everything */ + srtp_dealloc(*session); + *session = NULL; + return stat; + } + + /* set policy to next item in list */ + policy = policy->next; + } + + return srtp_err_status_ok; +} + +srtp_err_status_t srtp_remove_stream(srtp_t session, uint32_t ssrc) +{ + srtp_stream_ctx_t *stream, *last_stream; + srtp_err_status_t status; + + /* sanity check arguments */ + if (session == NULL) + return srtp_err_status_bad_param; + + /* find stream in list; complain if not found */ + last_stream = stream = session->stream_list; + while ((stream != NULL) && (ssrc != stream->ssrc)) { + last_stream = stream; + stream = stream->next; + } + if (stream == NULL) + return srtp_err_status_no_ctx; + + /* remove stream from the list */ + if (last_stream == stream) + /* stream was first in list */ + session->stream_list = stream->next; + else + last_stream->next = stream->next; + + /* deallocate the stream */ + status = srtp_stream_dealloc(stream, session->stream_template); + if (status) + return status; + + return srtp_err_status_ok; +} + +srtp_err_status_t srtp_update(srtp_t session, const srtp_policy_t *policy) +{ + srtp_err_status_t stat; + + stat = srtp_valid_policy(policy); + if (stat != srtp_err_status_ok) { + return stat; + } + + /* sanity check arguments */ + if ((session == NULL) || (policy == NULL) || + (!srtp_validate_policy_master_keys(policy))) { + return srtp_err_status_bad_param; + } + + while (policy != NULL) { + stat = srtp_update_stream(session, policy); + if (stat) { + return stat; + } + + /* set policy to next item in list */ + policy = policy->next; + } + return srtp_err_status_ok; +} + +static srtp_err_status_t update_template_streams(srtp_t session, + const srtp_policy_t *policy) +{ + srtp_err_status_t status; + srtp_stream_t new_stream_template; + srtp_stream_t new_stream_list = NULL; + + status = srtp_valid_policy(policy); + if (status != srtp_err_status_ok) { + return status; + } + + if (session->stream_template == NULL) { + return srtp_err_status_bad_param; + } + + /* allocate new template stream */ + status = srtp_stream_alloc(&new_stream_template, policy); + if (status) { + return status; + } + + /* initialize new template stream */ + status = srtp_stream_init(new_stream_template, policy); + if (status) { + srtp_crypto_free(new_stream_template); + return status; + } + + /* for all old templated streams */ + for (;;) { + srtp_stream_t stream; + uint32_t ssrc; + srtp_xtd_seq_num_t old_index; + srtp_rdb_t old_rtcp_rdb; + + stream = session->stream_list; + while ((stream != NULL) && + (stream->session_keys[0].rtp_auth != + session->stream_template->session_keys[0].rtp_auth)) { + stream = stream->next; + } + if (stream == NULL) { + /* no more templated streams */ + break; + } + + /* save old extendard seq */ + ssrc = stream->ssrc; + old_index = stream->rtp_rdbx.index; + old_rtcp_rdb = stream->rtcp_rdb; + + /* remove stream */ + status = srtp_remove_stream(session, ssrc); + if (status) { + /* free new allocations */ + while (new_stream_list != NULL) { + srtp_stream_t next = new_stream_list->next; + srtp_stream_dealloc(new_stream_list, new_stream_template); + new_stream_list = next; + } + srtp_stream_dealloc(new_stream_template, NULL); + return status; + } + + /* allocate and initialize a new stream */ + status = srtp_stream_clone(new_stream_template, ssrc, &stream); + if (status) { + /* free new allocations */ + while (new_stream_list != NULL) { + srtp_stream_t next = new_stream_list->next; + srtp_stream_dealloc(new_stream_list, new_stream_template); + new_stream_list = next; + } + srtp_stream_dealloc(new_stream_template, NULL); + return status; + } + + /* add new stream to the head of the new_stream_list */ + stream->next = new_stream_list; + new_stream_list = stream; + + /* restore old extended seq */ + stream->rtp_rdbx.index = old_index; + stream->rtcp_rdb = old_rtcp_rdb; + } + /* dealloc old template */ + srtp_stream_dealloc(session->stream_template, NULL); + /* set new template */ + session->stream_template = new_stream_template; + /* add new list */ + if (new_stream_list) { + srtp_stream_t tail = new_stream_list; + while (tail->next) { + tail = tail->next; + } + tail->next = session->stream_list; + session->stream_list = new_stream_list; + } + return status; +} + +static srtp_err_status_t update_stream(srtp_t session, + const srtp_policy_t *policy) +{ + srtp_err_status_t status; + srtp_xtd_seq_num_t old_index; + srtp_rdb_t old_rtcp_rdb; + srtp_stream_t stream; + + status = srtp_valid_policy(policy); + if (status != srtp_err_status_ok) { + return status; + } + + stream = srtp_get_stream(session, htonl(policy->ssrc.value)); + if (stream == NULL) { + return srtp_err_status_bad_param; + } + + /* save old extendard seq */ + old_index = stream->rtp_rdbx.index; + old_rtcp_rdb = stream->rtcp_rdb; + + status = srtp_remove_stream(session, htonl(policy->ssrc.value)); + if (status) { + return status; + } + + status = srtp_add_stream(session, policy); + if (status) { + return status; + } + + stream = srtp_get_stream(session, htonl(policy->ssrc.value)); + if (stream == NULL) { + return srtp_err_status_fail; + } + + /* restore old extended seq */ + stream->rtp_rdbx.index = old_index; + stream->rtcp_rdb = old_rtcp_rdb; + + return srtp_err_status_ok; +} + +srtp_err_status_t srtp_update_stream(srtp_t session, + const srtp_policy_t *policy) +{ + srtp_err_status_t status; + + status = srtp_valid_policy(policy); + if (status != srtp_err_status_ok) { + return status; + } + + /* sanity check arguments */ + if ((session == NULL) || (policy == NULL) || + (!srtp_validate_policy_master_keys(policy))) + return srtp_err_status_bad_param; + + switch (policy->ssrc.type) { + case (ssrc_any_outbound): + case (ssrc_any_inbound): + status = update_template_streams(session, policy); + break; + case (ssrc_specific): + status = update_stream(session, policy); + break; + case (ssrc_undefined): + default: + return srtp_err_status_bad_param; + } + + return status; +} + +/* + * The default policy - provides a convenient way for callers to use + * the default security policy + * + * The default policy is defined in RFC 3711 + * (Section 5. Default and mandatory-to-implement Transforms) + * + */ + +/* + * NOTE: cipher_key_len is really key len (128 bits) plus salt len + * (112 bits) + */ +/* There are hard-coded 16's for base_key_len in the key generation code */ + +void srtp_crypto_policy_set_rtp_default(srtp_crypto_policy_t *p) +{ + p->cipher_type = SRTP_AES_ICM_128; + p->cipher_key_len = + SRTP_AES_ICM_128_KEY_LEN_WSALT; /* default 128 bits per RFC 3711 */ + p->auth_type = SRTP_HMAC_SHA1; + p->auth_key_len = 20; /* default 160 bits per RFC 3711 */ + p->auth_tag_len = 10; /* default 80 bits per RFC 3711 */ + p->sec_serv = sec_serv_conf_and_auth; +} + +void srtp_crypto_policy_set_rtcp_default(srtp_crypto_policy_t *p) +{ + p->cipher_type = SRTP_AES_ICM_128; + p->cipher_key_len = + SRTP_AES_ICM_128_KEY_LEN_WSALT; /* default 128 bits per RFC 3711 */ + p->auth_type = SRTP_HMAC_SHA1; + p->auth_key_len = 20; /* default 160 bits per RFC 3711 */ + p->auth_tag_len = 10; /* default 80 bits per RFC 3711 */ + p->sec_serv = sec_serv_conf_and_auth; +} + +void srtp_crypto_policy_set_aes_cm_128_hmac_sha1_32(srtp_crypto_policy_t *p) +{ + /* + * corresponds to RFC 4568 + * + * note that this crypto policy is intended for SRTP, but not SRTCP + */ + + p->cipher_type = SRTP_AES_ICM_128; + p->cipher_key_len = + SRTP_AES_ICM_128_KEY_LEN_WSALT; /* 128 bit key, 112 bit salt */ + p->auth_type = SRTP_HMAC_SHA1; + p->auth_key_len = 20; /* 160 bit key */ + p->auth_tag_len = 4; /* 32 bit tag */ + p->sec_serv = sec_serv_conf_and_auth; +} + +void srtp_crypto_policy_set_aes_cm_128_null_auth(srtp_crypto_policy_t *p) +{ + /* + * corresponds to RFC 4568 + * + * note that this crypto policy is intended for SRTP, but not SRTCP + */ + + p->cipher_type = SRTP_AES_ICM_128; + p->cipher_key_len = + SRTP_AES_ICM_128_KEY_LEN_WSALT; /* 128 bit key, 112 bit salt */ + p->auth_type = SRTP_NULL_AUTH; + p->auth_key_len = 0; + p->auth_tag_len = 0; + p->sec_serv = sec_serv_conf; +} + +void srtp_crypto_policy_set_null_cipher_hmac_sha1_80(srtp_crypto_policy_t *p) +{ + /* + * corresponds to RFC 4568 + */ + + p->cipher_type = SRTP_NULL_CIPHER; + p->cipher_key_len = 16; + p->auth_type = SRTP_HMAC_SHA1; + p->auth_key_len = 20; + p->auth_tag_len = 10; + p->sec_serv = sec_serv_auth; +} + +void srtp_crypto_policy_set_null_cipher_hmac_null(srtp_crypto_policy_t *p) +{ + /* + * Should only be used for testing + */ + + p->cipher_type = SRTP_NULL_CIPHER; + p->cipher_key_len = 16; + p->auth_type = SRTP_NULL_AUTH; + p->auth_key_len = 0; + p->auth_tag_len = 0; + p->sec_serv = sec_serv_none; +} + +void srtp_crypto_policy_set_aes_cm_256_hmac_sha1_80(srtp_crypto_policy_t *p) +{ + /* + * corresponds to RFC 6188 + */ + + p->cipher_type = SRTP_AES_ICM_256; + p->cipher_key_len = SRTP_AES_ICM_256_KEY_LEN_WSALT; + p->auth_type = SRTP_HMAC_SHA1; + p->auth_key_len = 20; /* default 160 bits per RFC 3711 */ + p->auth_tag_len = 10; /* default 80 bits per RFC 3711 */ + p->sec_serv = sec_serv_conf_and_auth; +} + +void srtp_crypto_policy_set_aes_cm_256_hmac_sha1_32(srtp_crypto_policy_t *p) +{ + /* + * corresponds to RFC 6188 + * + * note that this crypto policy is intended for SRTP, but not SRTCP + */ + + p->cipher_type = SRTP_AES_ICM_256; + p->cipher_key_len = SRTP_AES_ICM_256_KEY_LEN_WSALT; + p->auth_type = SRTP_HMAC_SHA1; + p->auth_key_len = 20; /* default 160 bits per RFC 3711 */ + p->auth_tag_len = 4; /* default 80 bits per RFC 3711 */ + p->sec_serv = sec_serv_conf_and_auth; +} + +/* + * AES-256 with no authentication. + */ +void srtp_crypto_policy_set_aes_cm_256_null_auth(srtp_crypto_policy_t *p) +{ + p->cipher_type = SRTP_AES_ICM_256; + p->cipher_key_len = SRTP_AES_ICM_256_KEY_LEN_WSALT; + p->auth_type = SRTP_NULL_AUTH; + p->auth_key_len = 0; + p->auth_tag_len = 0; + p->sec_serv = sec_serv_conf; +} + +void srtp_crypto_policy_set_aes_cm_192_hmac_sha1_80(srtp_crypto_policy_t *p) +{ + /* + * corresponds to RFC 6188 + */ + + p->cipher_type = SRTP_AES_ICM_192; + p->cipher_key_len = SRTP_AES_ICM_192_KEY_LEN_WSALT; + p->auth_type = SRTP_HMAC_SHA1; + p->auth_key_len = 20; /* default 160 bits per RFC 3711 */ + p->auth_tag_len = 10; /* default 80 bits per RFC 3711 */ + p->sec_serv = sec_serv_conf_and_auth; +} + +void srtp_crypto_policy_set_aes_cm_192_hmac_sha1_32(srtp_crypto_policy_t *p) +{ + /* + * corresponds to RFC 6188 + * + * note that this crypto policy is intended for SRTP, but not SRTCP + */ + + p->cipher_type = SRTP_AES_ICM_192; + p->cipher_key_len = SRTP_AES_ICM_192_KEY_LEN_WSALT; + p->auth_type = SRTP_HMAC_SHA1; + p->auth_key_len = 20; /* default 160 bits per RFC 3711 */ + p->auth_tag_len = 4; /* default 80 bits per RFC 3711 */ + p->sec_serv = sec_serv_conf_and_auth; +} + +/* + * AES-192 with no authentication. + */ +void srtp_crypto_policy_set_aes_cm_192_null_auth(srtp_crypto_policy_t *p) +{ + p->cipher_type = SRTP_AES_ICM_192; + p->cipher_key_len = SRTP_AES_ICM_192_KEY_LEN_WSALT; + p->auth_type = SRTP_NULL_AUTH; + p->auth_key_len = 0; + p->auth_tag_len = 0; + p->sec_serv = sec_serv_conf; +} + +/* + * AES-128 GCM mode with 8 octet auth tag. + */ +void srtp_crypto_policy_set_aes_gcm_128_8_auth(srtp_crypto_policy_t *p) +{ + p->cipher_type = SRTP_AES_GCM_128; + p->cipher_key_len = SRTP_AES_GCM_128_KEY_LEN_WSALT; + p->auth_type = SRTP_NULL_AUTH; /* GCM handles the auth for us */ + p->auth_key_len = 0; + p->auth_tag_len = 8; /* 8 octet tag length */ + p->sec_serv = sec_serv_conf_and_auth; +} + +/* + * AES-256 GCM mode with 8 octet auth tag. + */ +void srtp_crypto_policy_set_aes_gcm_256_8_auth(srtp_crypto_policy_t *p) +{ + p->cipher_type = SRTP_AES_GCM_256; + p->cipher_key_len = SRTP_AES_GCM_256_KEY_LEN_WSALT; + p->auth_type = SRTP_NULL_AUTH; /* GCM handles the auth for us */ + p->auth_key_len = 0; + p->auth_tag_len = 8; /* 8 octet tag length */ + p->sec_serv = sec_serv_conf_and_auth; +} + +/* + * AES-128 GCM mode with 8 octet auth tag, no RTCP encryption. + */ +void srtp_crypto_policy_set_aes_gcm_128_8_only_auth(srtp_crypto_policy_t *p) +{ + p->cipher_type = SRTP_AES_GCM_128; + p->cipher_key_len = SRTP_AES_GCM_128_KEY_LEN_WSALT; + p->auth_type = SRTP_NULL_AUTH; /* GCM handles the auth for us */ + p->auth_key_len = 0; + p->auth_tag_len = 8; /* 8 octet tag length */ + p->sec_serv = sec_serv_auth; /* This only applies to RTCP */ +} + +/* + * AES-256 GCM mode with 8 octet auth tag, no RTCP encryption. + */ +void srtp_crypto_policy_set_aes_gcm_256_8_only_auth(srtp_crypto_policy_t *p) +{ + p->cipher_type = SRTP_AES_GCM_256; + p->cipher_key_len = SRTP_AES_GCM_256_KEY_LEN_WSALT; + p->auth_type = SRTP_NULL_AUTH; /* GCM handles the auth for us */ + p->auth_key_len = 0; + p->auth_tag_len = 8; /* 8 octet tag length */ + p->sec_serv = sec_serv_auth; /* This only applies to RTCP */ +} + +/* + * AES-128 GCM mode with 16 octet auth tag. + */ +void srtp_crypto_policy_set_aes_gcm_128_16_auth(srtp_crypto_policy_t *p) +{ + p->cipher_type = SRTP_AES_GCM_128; + p->cipher_key_len = SRTP_AES_GCM_128_KEY_LEN_WSALT; + p->auth_type = SRTP_NULL_AUTH; /* GCM handles the auth for us */ + p->auth_key_len = 0; + p->auth_tag_len = 16; /* 16 octet tag length */ + p->sec_serv = sec_serv_conf_and_auth; +} + +/* + * AES-256 GCM mode with 16 octet auth tag. + */ +void srtp_crypto_policy_set_aes_gcm_256_16_auth(srtp_crypto_policy_t *p) +{ + p->cipher_type = SRTP_AES_GCM_256; + p->cipher_key_len = SRTP_AES_GCM_256_KEY_LEN_WSALT; + p->auth_type = SRTP_NULL_AUTH; /* GCM handles the auth for us */ + p->auth_key_len = 0; + p->auth_tag_len = 16; /* 16 octet tag length */ + p->sec_serv = sec_serv_conf_and_auth; +} + +/* + * secure rtcp functions + */ + +/* + * AEAD uses a new IV formation method. This function implements + * section 9.1 (SRTCP IV Formation for AES-GCM) from RFC7714. + * The calculation is defined as, where (+) is the xor operation: + * + * 0 1 2 3 4 5 6 7 8 9 10 11 + * +--+--+--+--+--+--+--+--+--+--+--+--+ + * |00|00| SSRC |00|00|0+SRTCP Idx|---+ + * +--+--+--+--+--+--+--+--+--+--+--+--+ | + * | + * +--+--+--+--+--+--+--+--+--+--+--+--+ | + * | Encryption Salt |->(+) + * +--+--+--+--+--+--+--+--+--+--+--+--+ | + * | + * +--+--+--+--+--+--+--+--+--+--+--+--+ | + * | Initialization Vector |<--+ + * +--+--+--+--+--+--+--+--+--+--+--+--+* + * + * Input: *session_keys - pointer to SRTP stream context session keys, + * used to retrieve the SALT + * *iv - Pointer to recieve the calculated IV + * seq_num - The SEQ value to use for the IV calculation. + * *hdr - The RTP header, used to get the SSRC value + * + * Returns: srtp_err_status_ok if no error or srtp_err_status_bad_param + * if seq_num is invalid + * + */ +static srtp_err_status_t srtp_calc_aead_iv_srtcp( + srtp_session_keys_t *session_keys, + v128_t *iv, + uint32_t seq_num, + srtcp_hdr_t *hdr) +{ + v128_t in; + v128_t salt; + + memset(&in, 0, sizeof(v128_t)); + memset(&salt, 0, sizeof(v128_t)); + + in.v16[0] = 0; + memcpy(&in.v16[1], &hdr->ssrc, 4); /* still in network order! */ + in.v16[3] = 0; + + /* + * The SRTCP index (seq_num) spans bits 0 through 30 inclusive. + * The most significant bit should be zero. + */ + if (seq_num & 0x80000000UL) { + return srtp_err_status_bad_param; + } + in.v32[2] = htonl(seq_num); + + debug_print(mod_srtp, "Pre-salted RTCP IV = %s\n", v128_hex_string(&in)); + + /* + * Get the SALT value from the context + */ + memcpy(salt.v8, session_keys->c_salt, 12); + debug_print(mod_srtp, "RTCP SALT = %s\n", v128_hex_string(&salt)); + + /* + * Finally, apply the SALT to the input + */ + v128_xor(iv, &in, &salt); + + return srtp_err_status_ok; +} + +/* + * This code handles AEAD ciphers for outgoing RTCP. We currently support + * AES-GCM mode with 128 or 256 bit keys. + */ +static srtp_err_status_t srtp_protect_rtcp_aead( + srtp_t ctx, + srtp_stream_ctx_t *stream, + void *rtcp_hdr, + unsigned int *pkt_octet_len, + srtp_session_keys_t *session_keys, + unsigned int use_mki) +{ + srtcp_hdr_t *hdr = (srtcp_hdr_t *)rtcp_hdr; + uint32_t *enc_start; /* pointer to start of encrypted portion */ + uint32_t *trailer_p; /* pointer to start of trailer */ + uint32_t trailer; /* trailer value */ + unsigned int enc_octet_len = 0; /* number of octets in encrypted portion */ + uint8_t *auth_tag = NULL; /* location of auth_tag within packet */ + srtp_err_status_t status; + uint32_t tag_len; + uint32_t seq_num; + v128_t iv; + uint32_t tseq; + unsigned int mki_size = 0; + + /* get tag length from stream context */ + tag_len = srtp_auth_get_tag_length(session_keys->rtcp_auth); + + /* + * set encryption start and encryption length - if we're not + * providing confidentiality, set enc_start to NULL + */ + enc_start = (uint32_t *)hdr + uint32s_in_rtcp_header; + enc_octet_len = *pkt_octet_len - octets_in_rtcp_header; + + /* NOTE: hdr->length is not usable - it refers to only the first + * RTCP report in the compound packet! + */ + trailer_p = (uint32_t *)((char *)enc_start + enc_octet_len + tag_len); + + if (stream->rtcp_services & sec_serv_conf) { + trailer = htonl(SRTCP_E_BIT); /* set encrypt bit */ + } else { + enc_start = NULL; + enc_octet_len = 0; + /* 0 is network-order independant */ + trailer = 0x00000000; /* set encrypt bit */ + } + + mki_size = srtp_inject_mki((uint8_t *)hdr + *pkt_octet_len + tag_len + + sizeof(srtcp_trailer_t), + session_keys, use_mki); + + /* + * set the auth_tag pointer to the proper location, which is after + * the payload, but before the trailer + * (note that srtpc *always* provides authentication, unlike srtp) + */ + /* Note: This would need to change for optional mikey data */ + auth_tag = (uint8_t *)hdr + *pkt_octet_len; + + /* + * check sequence number for overruns, and copy it into the packet + * if its value isn't too big + */ + status = srtp_rdb_increment(&stream->rtcp_rdb); + if (status) { + return status; + } + seq_num = srtp_rdb_get_value(&stream->rtcp_rdb); + trailer |= htonl(seq_num); + debug_print(mod_srtp, "srtcp index: %x", seq_num); + + memcpy(trailer_p, &trailer, sizeof(trailer)); + + /* + * Calculate and set the IV + */ + status = srtp_calc_aead_iv_srtcp(session_keys, &iv, seq_num, hdr); + if (status) { + return srtp_err_status_cipher_fail; + } + status = srtp_cipher_set_iv(session_keys->rtcp_cipher, (uint8_t *)&iv, + srtp_direction_encrypt); + if (status) { + return srtp_err_status_cipher_fail; + } + + /* + * Set the AAD for GCM mode + */ + if (enc_start) { + /* + * If payload encryption is enabled, then the AAD consist of + * the RTCP header and the seq# at the end of the packet + */ + status = srtp_cipher_set_aad(session_keys->rtcp_cipher, (uint8_t *)hdr, + octets_in_rtcp_header); + if (status) { + return (srtp_err_status_cipher_fail); + } + } else { + /* + * Since payload encryption is not enabled, we must authenticate + * the entire packet as described in RFC 7714 (Section 9.3. Data + * Types in Unencrypted SRTCP Compound Packets) + */ + status = srtp_cipher_set_aad(session_keys->rtcp_cipher, (uint8_t *)hdr, + *pkt_octet_len); + if (status) { + return (srtp_err_status_cipher_fail); + } + } + /* + * Process the sequence# as AAD + */ + tseq = trailer; + status = srtp_cipher_set_aad(session_keys->rtcp_cipher, (uint8_t *)&tseq, + sizeof(srtcp_trailer_t)); + if (status) { + return (srtp_err_status_cipher_fail); + } + + /* if we're encrypting, exor keystream into the message */ + if (enc_start) { + status = srtp_cipher_encrypt(session_keys->rtcp_cipher, + (uint8_t *)enc_start, &enc_octet_len); + if (status) { + return srtp_err_status_cipher_fail; + } + /* + * Get the tag and append that to the output + */ + status = srtp_cipher_get_tag(session_keys->rtcp_cipher, + (uint8_t *)auth_tag, &tag_len); + if (status) { + return (srtp_err_status_cipher_fail); + } + enc_octet_len += tag_len; + } else { + /* + * Even though we're not encrypting the payload, we need + * to run the cipher to get the auth tag. + */ + unsigned int nolen = 0; + status = srtp_cipher_encrypt(session_keys->rtcp_cipher, NULL, &nolen); + if (status) { + return srtp_err_status_cipher_fail; + } + /* + * Get the tag and append that to the output + */ + status = srtp_cipher_get_tag(session_keys->rtcp_cipher, + (uint8_t *)auth_tag, &tag_len); + if (status) { + return (srtp_err_status_cipher_fail); + } + enc_octet_len += tag_len; + } + + /* increase the packet length by the length of the auth tag and seq_num*/ + *pkt_octet_len += (tag_len + sizeof(srtcp_trailer_t)); + + /* increase the packet by the mki_size */ + *pkt_octet_len += mki_size; + + return srtp_err_status_ok; +} + +/* + * This function handles incoming SRTCP packets while in AEAD mode, + * which currently supports AES-GCM encryption. Note, the auth tag is + * at the end of the packet stream and is automatically checked by GCM + * when decrypting the payload. + */ +static srtp_err_status_t srtp_unprotect_rtcp_aead( + srtp_t ctx, + srtp_stream_ctx_t *stream, + void *srtcp_hdr, + unsigned int *pkt_octet_len, + srtp_session_keys_t *session_keys, + unsigned int use_mki) +{ + srtcp_hdr_t *hdr = (srtcp_hdr_t *)srtcp_hdr; + uint32_t *enc_start; /* pointer to start of encrypted portion */ + uint32_t *trailer_p; /* pointer to start of trailer */ + uint32_t trailer; /* trailer value */ + unsigned int enc_octet_len = 0; /* number of octets in encrypted portion */ + uint8_t *auth_tag = NULL; /* location of auth_tag within packet */ + srtp_err_status_t status; + int tag_len; + unsigned int tmp_len; + uint32_t seq_num; + v128_t iv; + uint32_t tseq; + unsigned int mki_size = 0; + + /* get tag length from stream context */ + tag_len = srtp_auth_get_tag_length(session_keys->rtcp_auth); + + if (use_mki) { + mki_size = session_keys->mki_size; + } + + /* + * set encryption start, encryption length, and trailer + */ + /* index & E (encryption) bit follow normal data. hdr->len is the number of + * words (32-bit) in the normal packet minus 1 + */ + /* This should point trailer to the word past the end of the normal data. */ + /* This would need to be modified for optional mikey data */ + trailer_p = (uint32_t *)((char *)hdr + *pkt_octet_len - + sizeof(srtcp_trailer_t) - mki_size); + memcpy(&trailer, trailer_p, sizeof(trailer)); + + /* + * We pass the tag down to the cipher when doing GCM mode + */ + enc_octet_len = *pkt_octet_len - (octets_in_rtcp_header + + sizeof(srtcp_trailer_t) + mki_size); + auth_tag = (uint8_t *)hdr + *pkt_octet_len - tag_len - mki_size - + sizeof(srtcp_trailer_t); + + if (*((unsigned char *)trailer_p) & SRTCP_E_BYTE_BIT) { + enc_start = (uint32_t *)hdr + uint32s_in_rtcp_header; + } else { + enc_octet_len = 0; + enc_start = NULL; /* this indicates that there's no encryption */ + } + + /* + * check the sequence number for replays + */ + /* this is easier than dealing with bitfield access */ + seq_num = ntohl(trailer) & SRTCP_INDEX_MASK; + debug_print(mod_srtp, "srtcp index: %x", seq_num); + status = srtp_rdb_check(&stream->rtcp_rdb, seq_num); + if (status) { + return status; + } + + /* + * Calculate and set the IV + */ + status = srtp_calc_aead_iv_srtcp(session_keys, &iv, seq_num, hdr); + if (status) { + return srtp_err_status_cipher_fail; + } + status = srtp_cipher_set_iv(session_keys->rtcp_cipher, (uint8_t *)&iv, + srtp_direction_decrypt); + if (status) { + return srtp_err_status_cipher_fail; + } + + /* + * Set the AAD for GCM mode + */ + if (enc_start) { + /* + * If payload encryption is enabled, then the AAD consist of + * the RTCP header and the seq# at the end of the packet + */ + status = srtp_cipher_set_aad(session_keys->rtcp_cipher, (uint8_t *)hdr, + octets_in_rtcp_header); + if (status) { + return (srtp_err_status_cipher_fail); + } + } else { + /* + * Since payload encryption is not enabled, we must authenticate + * the entire packet as described in RFC 7714 (Section 9.3. Data + * Types in Unencrypted SRTCP Compound Packets) + */ + status = srtp_cipher_set_aad( + session_keys->rtcp_cipher, (uint8_t *)hdr, + (*pkt_octet_len - tag_len - sizeof(srtcp_trailer_t) - mki_size)); + if (status) { + return (srtp_err_status_cipher_fail); + } + } + + /* + * Process the sequence# as AAD + */ + tseq = trailer; + status = srtp_cipher_set_aad(session_keys->rtcp_cipher, (uint8_t *)&tseq, + sizeof(srtcp_trailer_t)); + if (status) { + return (srtp_err_status_cipher_fail); + } + + /* if we're decrypting, exor keystream into the message */ + if (enc_start) { + status = srtp_cipher_decrypt(session_keys->rtcp_cipher, + (uint8_t *)enc_start, &enc_octet_len); + if (status) { + return status; + } + } else { + /* + * Still need to run the cipher to check the tag + */ + tmp_len = tag_len; + status = srtp_cipher_decrypt(session_keys->rtcp_cipher, + (uint8_t *)auth_tag, &tmp_len); + if (status) { + return status; + } + } + + /* decrease the packet length by the length of the auth tag and seq_num*/ + *pkt_octet_len -= (tag_len + sizeof(srtcp_trailer_t) + mki_size); + + /* + * verify that stream is for received traffic - this check will + * detect SSRC collisions, since a stream that appears in both + * srtp_protect() and srtp_unprotect() will fail this test in one of + * those functions. + * + * we do this check *after* the authentication check, so that the + * latter check will catch any attempts to fool us into thinking + * that we've got a collision + */ + if (stream->direction != dir_srtp_receiver) { + if (stream->direction == dir_unknown) { + stream->direction = dir_srtp_receiver; + } else { + srtp_handle_event(ctx, stream, event_ssrc_collision); + } + } + + /* + * if the stream is a 'provisional' one, in which the template context + * is used, then we need to allocate a new stream at this point, since + * the authentication passed + */ + if (stream == ctx->stream_template) { + srtp_stream_ctx_t *new_stream; + + /* + * allocate and initialize a new stream + * + * note that we indicate failure if we can't allocate the new + * stream, and some implementations will want to not return + * failure here + */ + status = + srtp_stream_clone(ctx->stream_template, hdr->ssrc, &new_stream); + if (status) { + return status; + } + + /* add new stream to the head of the stream_list */ + new_stream->next = ctx->stream_list; + ctx->stream_list = new_stream; + + /* set stream (the pointer used in this function) */ + stream = new_stream; + } + + /* we've passed the authentication check, so add seq_num to the rdb */ + srtp_rdb_add_index(&stream->rtcp_rdb, seq_num); + + return srtp_err_status_ok; +} + +srtp_err_status_t srtp_protect_rtcp(srtp_t ctx, + void *rtcp_hdr, + int *pkt_octet_len) +{ + return srtp_protect_rtcp_mki(ctx, rtcp_hdr, pkt_octet_len, 0, 0); +} + +srtp_err_status_t srtp_protect_rtcp_mki(srtp_t ctx, + void *rtcp_hdr, + int *pkt_octet_len, + unsigned int use_mki, + unsigned int mki_index) +{ + srtcp_hdr_t *hdr = (srtcp_hdr_t *)rtcp_hdr; + uint32_t *enc_start; /* pointer to start of encrypted portion */ + uint32_t *auth_start; /* pointer to start of auth. portion */ + uint32_t *trailer_p; /* pointer to start of trailer */ + uint32_t trailer; /* trailer value */ + unsigned int enc_octet_len = 0; /* number of octets in encrypted portion */ + uint8_t *auth_tag = NULL; /* location of auth_tag within packet */ + srtp_err_status_t status; + int tag_len; + srtp_stream_ctx_t *stream; + uint32_t prefix_len; + uint32_t seq_num; + unsigned int mki_size = 0; + srtp_session_keys_t *session_keys = NULL; + + /* we assume the hdr is 32-bit aligned to start */ + + /* check the packet length - it must at least contain a full header */ + if (*pkt_octet_len < octets_in_rtcp_header) + return srtp_err_status_bad_param; + + /* + * look up ssrc in srtp_stream list, and process the packet with + * the appropriate stream. if we haven't seen this stream before, + * there's only one key for this srtp_session, and the cipher + * supports key-sharing, then we assume that a new stream using + * that key has just started up + */ + stream = srtp_get_stream(ctx, hdr->ssrc); + if (stream == NULL) { + if (ctx->stream_template != NULL) { + srtp_stream_ctx_t *new_stream; + + /* allocate and initialize a new stream */ + status = + srtp_stream_clone(ctx->stream_template, hdr->ssrc, &new_stream); + if (status) + return status; + + /* add new stream to the head of the stream_list */ + new_stream->next = ctx->stream_list; + ctx->stream_list = new_stream; + + /* set stream (the pointer used in this function) */ + stream = new_stream; + } else { + /* no template stream, so we return an error */ + return srtp_err_status_no_ctx; + } + } + + /* + * verify that stream is for sending traffic - this check will + * detect SSRC collisions, since a stream that appears in both + * srtp_protect() and srtp_unprotect() will fail this test in one of + * those functions. + */ + if (stream->direction != dir_srtp_sender) { + if (stream->direction == dir_unknown) { + stream->direction = dir_srtp_sender; + } else { + srtp_handle_event(ctx, stream, event_ssrc_collision); + } + } + + session_keys = + srtp_get_session_keys_with_mki_index(stream, use_mki, mki_index); + + if (session_keys == NULL) + return srtp_err_status_bad_mki; + + /* + * Check if this is an AEAD stream (GCM mode). If so, then dispatch + * the request to our AEAD handler. + */ + if (session_keys->rtp_cipher->algorithm == SRTP_AES_GCM_128 || + session_keys->rtp_cipher->algorithm == SRTP_AES_GCM_256) { + return srtp_protect_rtcp_aead(ctx, stream, rtcp_hdr, + (unsigned int *)pkt_octet_len, + session_keys, use_mki); + } + + /* get tag length from stream context */ + tag_len = srtp_auth_get_tag_length(session_keys->rtcp_auth); + + /* + * set encryption start and encryption length - if we're not + * providing confidentiality, set enc_start to NULL + */ + enc_start = (uint32_t *)hdr + uint32s_in_rtcp_header; + enc_octet_len = *pkt_octet_len - octets_in_rtcp_header; + + /* all of the packet, except the header, gets encrypted */ + /* + * NOTE: hdr->length is not usable - it refers to only the first RTCP report + * in the compound packet! + */ + trailer_p = (uint32_t *)((char *)enc_start + enc_octet_len); + + if (stream->rtcp_services & sec_serv_conf) { + trailer = htonl(SRTCP_E_BIT); /* set encrypt bit */ + } else { + enc_start = NULL; + enc_octet_len = 0; + /* 0 is network-order independant */ + trailer = 0x00000000; /* set encrypt bit */ + } + + mki_size = srtp_inject_mki((uint8_t *)hdr + *pkt_octet_len + + sizeof(srtcp_trailer_t), + session_keys, use_mki); + + /* + * set the auth_start and auth_tag pointers to the proper locations + * (note that srtpc *always* provides authentication, unlike srtp) + */ + /* Note: This would need to change for optional mikey data */ + auth_start = (uint32_t *)hdr; + auth_tag = + (uint8_t *)hdr + *pkt_octet_len + sizeof(srtcp_trailer_t) + mki_size; + + /* + * check sequence number for overruns, and copy it into the packet + * if its value isn't too big + */ + status = srtp_rdb_increment(&stream->rtcp_rdb); + if (status) + return status; + seq_num = srtp_rdb_get_value(&stream->rtcp_rdb); + trailer |= htonl(seq_num); + debug_print(mod_srtp, "srtcp index: %x", seq_num); + + memcpy(trailer_p, &trailer, sizeof(trailer)); + + /* + * if we're using rindael counter mode, set nonce and seq + */ + if (session_keys->rtcp_cipher->type->id == SRTP_AES_ICM_128 || + session_keys->rtcp_cipher->type->id == SRTP_AES_ICM_192 || + session_keys->rtcp_cipher->type->id == SRTP_AES_ICM_256) { + v128_t iv; + + iv.v32[0] = 0; + iv.v32[1] = hdr->ssrc; /* still in network order! */ + iv.v32[2] = htonl(seq_num >> 16); + iv.v32[3] = htonl(seq_num << 16); + status = srtp_cipher_set_iv(session_keys->rtcp_cipher, (uint8_t *)&iv, + srtp_direction_encrypt); + + } else { + v128_t iv; + + /* otherwise, just set the index to seq_num */ + iv.v32[0] = 0; + iv.v32[1] = 0; + iv.v32[2] = 0; + iv.v32[3] = htonl(seq_num); + status = srtp_cipher_set_iv(session_keys->rtcp_cipher, (uint8_t *)&iv, + srtp_direction_encrypt); + } + if (status) + return srtp_err_status_cipher_fail; + + /* + * if we're authenticating using a universal hash, put the keystream + * prefix into the authentication tag + */ + + /* if auth_start is non-null, then put keystream into tag */ + if (auth_start) { + /* put keystream prefix into auth_tag */ + prefix_len = srtp_auth_get_prefix_length(session_keys->rtcp_auth); + status = srtp_cipher_output(session_keys->rtcp_cipher, auth_tag, + &prefix_len); + + debug_print(mod_srtp, "keystream prefix: %s", + srtp_octet_string_hex_string(auth_tag, prefix_len)); + + if (status) + return srtp_err_status_cipher_fail; + } + + /* if we're encrypting, exor keystream into the message */ + if (enc_start) { + status = srtp_cipher_encrypt(session_keys->rtcp_cipher, + (uint8_t *)enc_start, &enc_octet_len); + if (status) + return srtp_err_status_cipher_fail; + } + + /* initialize auth func context */ + status = srtp_auth_start(session_keys->rtcp_auth); + if (status) + return status; + + /* + * run auth func over packet (including trailer), and write the + * result at auth_tag + */ + status = + srtp_auth_compute(session_keys->rtcp_auth, (uint8_t *)auth_start, + (*pkt_octet_len) + sizeof(srtcp_trailer_t), auth_tag); + debug_print(mod_srtp, "srtcp auth tag: %s", + srtp_octet_string_hex_string(auth_tag, tag_len)); + if (status) + return srtp_err_status_auth_fail; + + /* increase the packet length by the length of the auth tag and seq_num*/ + *pkt_octet_len += (tag_len + sizeof(srtcp_trailer_t)); + + /* increase the packet by the mki_size */ + *pkt_octet_len += mki_size; + + return srtp_err_status_ok; +} + +srtp_err_status_t srtp_unprotect_rtcp(srtp_t ctx, + void *srtcp_hdr, + int *pkt_octet_len) +{ + return srtp_unprotect_rtcp_mki(ctx, srtcp_hdr, pkt_octet_len, 0); +} + +srtp_err_status_t srtp_unprotect_rtcp_mki(srtp_t ctx, + void *srtcp_hdr, + int *pkt_octet_len, + unsigned int use_mki) +{ + srtcp_hdr_t *hdr = (srtcp_hdr_t *)srtcp_hdr; + uint32_t *enc_start; /* pointer to start of encrypted portion */ + uint32_t *auth_start; /* pointer to start of auth. portion */ + uint32_t *trailer_p; /* pointer to start of trailer */ + uint32_t trailer; /* trailer value */ + unsigned int enc_octet_len = 0; /* number of octets in encrypted portion */ + uint8_t *auth_tag = NULL; /* location of auth_tag within packet */ + uint8_t tmp_tag[SRTP_MAX_TAG_LEN]; + srtp_err_status_t status; + unsigned int auth_len; + int tag_len; + srtp_stream_ctx_t *stream; + uint32_t prefix_len; + uint32_t seq_num; + int e_bit_in_packet; /* whether the E-bit was found in the packet */ + int sec_serv_confidentiality; /* whether confidentiality was requested */ + unsigned int mki_size = 0; + srtp_session_keys_t *session_keys = NULL; + + /* we assume the hdr is 32-bit aligned to start */ + + if (*pkt_octet_len < 0) + return srtp_err_status_bad_param; + + /* + * check that the length value is sane; we'll check again once we + * know the tag length, but we at least want to know that it is + * a positive value + */ + if ((unsigned int)(*pkt_octet_len) < + octets_in_rtcp_header + sizeof(srtcp_trailer_t)) + return srtp_err_status_bad_param; + + /* + * look up ssrc in srtp_stream list, and process the packet with + * the appropriate stream. if we haven't seen this stream before, + * there's only one key for this srtp_session, and the cipher + * supports key-sharing, then we assume that a new stream using + * that key has just started up + */ + stream = srtp_get_stream(ctx, hdr->ssrc); + if (stream == NULL) { + if (ctx->stream_template != NULL) { + stream = ctx->stream_template; + + debug_print(mod_srtp, + "srtcp using provisional stream (SSRC: 0x%08x)", + ntohl(hdr->ssrc)); + } else { + /* no template stream, so we return an error */ + return srtp_err_status_no_ctx; + } + } + + /* + * Determine if MKI is being used and what session keys should be used + */ + if (use_mki) { + session_keys = srtp_get_session_keys( + stream, (uint8_t *)hdr, (const unsigned int *)pkt_octet_len, + &mki_size); + + if (session_keys == NULL) + return srtp_err_status_bad_mki; + } else { + session_keys = &stream->session_keys[0]; + } + + /* get tag length from stream context */ + tag_len = srtp_auth_get_tag_length(session_keys->rtcp_auth); + + /* check the packet length - it must contain at least a full RTCP + header, an auth tag (if applicable), and the SRTCP encrypted flag + and 31-bit index value */ + if (*pkt_octet_len < (int)(octets_in_rtcp_header + tag_len + mki_size + + sizeof(srtcp_trailer_t))) { + return srtp_err_status_bad_param; + } + + /* + * Check if this is an AEAD stream (GCM mode). If so, then dispatch + * the request to our AEAD handler. + */ + if (session_keys->rtp_cipher->algorithm == SRTP_AES_GCM_128 || + session_keys->rtp_cipher->algorithm == SRTP_AES_GCM_256) { + return srtp_unprotect_rtcp_aead(ctx, stream, srtcp_hdr, + (unsigned int *)pkt_octet_len, + session_keys, mki_size); + } + + sec_serv_confidentiality = stream->rtcp_services == sec_serv_conf || + stream->rtcp_services == sec_serv_conf_and_auth; + + /* + * set encryption start, encryption length, and trailer + */ + enc_octet_len = *pkt_octet_len - (octets_in_rtcp_header + tag_len + + mki_size + sizeof(srtcp_trailer_t)); + /* + *index & E (encryption) bit follow normal data. hdr->len is the number of + * words (32-bit) in the normal packet minus 1 + */ + /* This should point trailer to the word past the end of the normal data. */ + /* This would need to be modified for optional mikey data */ + trailer_p = (uint32_t *)((char *)hdr + *pkt_octet_len - + (tag_len + mki_size + sizeof(srtcp_trailer_t))); + memcpy(&trailer, trailer_p, sizeof(trailer)); + + e_bit_in_packet = + (*((unsigned char *)trailer_p) & SRTCP_E_BYTE_BIT) == SRTCP_E_BYTE_BIT; + if (e_bit_in_packet != sec_serv_confidentiality) { + return srtp_err_status_cant_check; + } + if (sec_serv_confidentiality) { + enc_start = (uint32_t *)hdr + uint32s_in_rtcp_header; + } else { + enc_octet_len = 0; + enc_start = NULL; /* this indicates that there's no encryption */ + } + + /* + * set the auth_start and auth_tag pointers to the proper locations + * (note that srtcp *always* uses authentication, unlike srtp) + */ + auth_start = (uint32_t *)hdr; + + /* + * The location of the auth tag in the packet needs to know MKI + * could be present. The data needed to calculate the Auth tag + * must not include the MKI + */ + auth_len = *pkt_octet_len - tag_len - mki_size; + auth_tag = (uint8_t *)hdr + auth_len + mki_size; + + /* + * check the sequence number for replays + */ + /* this is easier than dealing with bitfield access */ + seq_num = ntohl(trailer) & SRTCP_INDEX_MASK; + debug_print(mod_srtp, "srtcp index: %x", seq_num); + status = srtp_rdb_check(&stream->rtcp_rdb, seq_num); + if (status) + return status; + + /* + * if we're using aes counter mode, set nonce and seq + */ + if (session_keys->rtcp_cipher->type->id == SRTP_AES_ICM_128 || + session_keys->rtcp_cipher->type->id == SRTP_AES_ICM_192 || + session_keys->rtcp_cipher->type->id == SRTP_AES_ICM_256) { + v128_t iv; + + iv.v32[0] = 0; + iv.v32[1] = hdr->ssrc; /* still in network order! */ + iv.v32[2] = htonl(seq_num >> 16); + iv.v32[3] = htonl(seq_num << 16); + status = srtp_cipher_set_iv(session_keys->rtcp_cipher, (uint8_t *)&iv, + srtp_direction_decrypt); + + } else { + v128_t iv; + + /* otherwise, just set the index to seq_num */ + iv.v32[0] = 0; + iv.v32[1] = 0; + iv.v32[2] = 0; + iv.v32[3] = htonl(seq_num); + status = srtp_cipher_set_iv(session_keys->rtcp_cipher, (uint8_t *)&iv, + srtp_direction_decrypt); + } + if (status) + return srtp_err_status_cipher_fail; + + /* initialize auth func context */ + status = srtp_auth_start(session_keys->rtcp_auth); + if (status) + return status; + + /* run auth func over packet, put result into tmp_tag */ + status = srtp_auth_compute(session_keys->rtcp_auth, (uint8_t *)auth_start, + auth_len, tmp_tag); + debug_print(mod_srtp, "srtcp computed tag: %s", + srtp_octet_string_hex_string(tmp_tag, tag_len)); + if (status) + return srtp_err_status_auth_fail; + + /* compare the tag just computed with the one in the packet */ + debug_print(mod_srtp, "srtcp tag from packet: %s", + srtp_octet_string_hex_string(auth_tag, tag_len)); + if (srtp_octet_string_is_eq(tmp_tag, auth_tag, tag_len)) + return srtp_err_status_auth_fail; + + /* + * if we're authenticating using a universal hash, put the keystream + * prefix into the authentication tag + */ + prefix_len = srtp_auth_get_prefix_length(session_keys->rtcp_auth); + if (prefix_len) { + status = srtp_cipher_output(session_keys->rtcp_cipher, auth_tag, + &prefix_len); + debug_print(mod_srtp, "keystream prefix: %s", + srtp_octet_string_hex_string(auth_tag, prefix_len)); + if (status) + return srtp_err_status_cipher_fail; + } + + /* if we're decrypting, exor keystream into the message */ + if (enc_start) { + status = srtp_cipher_decrypt(session_keys->rtcp_cipher, + (uint8_t *)enc_start, &enc_octet_len); + if (status) + return srtp_err_status_cipher_fail; + } + + /* decrease the packet length by the length of the auth tag and seq_num */ + *pkt_octet_len -= (tag_len + sizeof(srtcp_trailer_t)); + + /* decrease the packet length by the length of the mki_size */ + *pkt_octet_len -= mki_size; + + /* + * verify that stream is for received traffic - this check will + * detect SSRC collisions, since a stream that appears in both + * srtp_protect() and srtp_unprotect() will fail this test in one of + * those functions. + * + * we do this check *after* the authentication check, so that the + * latter check will catch any attempts to fool us into thinking + * that we've got a collision + */ + if (stream->direction != dir_srtp_receiver) { + if (stream->direction == dir_unknown) { + stream->direction = dir_srtp_receiver; + } else { + srtp_handle_event(ctx, stream, event_ssrc_collision); + } + } + + /* + * if the stream is a 'provisional' one, in which the template context + * is used, then we need to allocate a new stream at this point, since + * the authentication passed + */ + if (stream == ctx->stream_template) { + srtp_stream_ctx_t *new_stream; + + /* + * allocate and initialize a new stream + * + * note that we indicate failure if we can't allocate the new + * stream, and some implementations will want to not return + * failure here + */ + status = + srtp_stream_clone(ctx->stream_template, hdr->ssrc, &new_stream); + if (status) + return status; + + /* add new stream to the head of the stream_list */ + new_stream->next = ctx->stream_list; + ctx->stream_list = new_stream; + + /* set stream (the pointer used in this function) */ + stream = new_stream; + } + + /* we've passed the authentication check, so add seq_num to the rdb */ + srtp_rdb_add_index(&stream->rtcp_rdb, seq_num); + + return srtp_err_status_ok; +} + +/* + * user data within srtp_t context + */ + +void srtp_set_user_data(srtp_t ctx, void *data) +{ + ctx->user_data = data; +} + +void *srtp_get_user_data(srtp_t ctx) +{ + return ctx->user_data; +} + +srtp_err_status_t srtp_crypto_policy_set_from_profile_for_rtp( + srtp_crypto_policy_t *policy, + srtp_profile_t profile) +{ + /* set SRTP policy from the SRTP profile in the key set */ + switch (profile) { + case srtp_profile_aes128_cm_sha1_80: + srtp_crypto_policy_set_aes_cm_128_hmac_sha1_80(policy); + break; + case srtp_profile_aes128_cm_sha1_32: + srtp_crypto_policy_set_aes_cm_128_hmac_sha1_32(policy); + break; + case srtp_profile_null_sha1_80: + srtp_crypto_policy_set_null_cipher_hmac_sha1_80(policy); + break; +#ifdef GCM + case srtp_profile_aead_aes_128_gcm: + srtp_crypto_policy_set_aes_gcm_128_16_auth(policy); + break; + case srtp_profile_aead_aes_256_gcm: + srtp_crypto_policy_set_aes_gcm_256_16_auth(policy); + break; +#endif + /* the following profiles are not (yet) supported */ + case srtp_profile_null_sha1_32: + default: + return srtp_err_status_bad_param; + } + + return srtp_err_status_ok; +} + +srtp_err_status_t srtp_crypto_policy_set_from_profile_for_rtcp( + srtp_crypto_policy_t *policy, + srtp_profile_t profile) +{ + /* set SRTP policy from the SRTP profile in the key set */ + switch (profile) { + case srtp_profile_aes128_cm_sha1_80: + srtp_crypto_policy_set_aes_cm_128_hmac_sha1_80(policy); + break; + case srtp_profile_aes128_cm_sha1_32: + /* We do not honor the 32-bit auth tag request since + * this is not compliant with RFC 3711 */ + srtp_crypto_policy_set_aes_cm_128_hmac_sha1_80(policy); + break; + case srtp_profile_null_sha1_80: + srtp_crypto_policy_set_null_cipher_hmac_sha1_80(policy); + break; +#ifdef GCM + case srtp_profile_aead_aes_128_gcm: + srtp_crypto_policy_set_aes_gcm_128_16_auth(policy); + break; + case srtp_profile_aead_aes_256_gcm: + srtp_crypto_policy_set_aes_gcm_256_16_auth(policy); + break; +#endif + /* the following profiles are not (yet) supported */ + case srtp_profile_null_sha1_32: + default: + return srtp_err_status_bad_param; + } + + return srtp_err_status_ok; +} + +void srtp_append_salt_to_key(uint8_t *key, + unsigned int bytes_in_key, + uint8_t *salt, + unsigned int bytes_in_salt) +{ + memcpy(key + bytes_in_key, salt, bytes_in_salt); +} + +unsigned int srtp_profile_get_master_key_length(srtp_profile_t profile) +{ + switch (profile) { + case srtp_profile_aes128_cm_sha1_80: + return SRTP_AES_128_KEY_LEN; + break; + case srtp_profile_aes128_cm_sha1_32: + return SRTP_AES_128_KEY_LEN; + break; + case srtp_profile_null_sha1_80: + return SRTP_AES_128_KEY_LEN; + break; + case srtp_profile_aead_aes_128_gcm: + return SRTP_AES_128_KEY_LEN; + break; + case srtp_profile_aead_aes_256_gcm: + return SRTP_AES_256_KEY_LEN; + break; + /* the following profiles are not (yet) supported */ + case srtp_profile_null_sha1_32: + default: + return 0; /* indicate error by returning a zero */ + } +} + +unsigned int srtp_profile_get_master_salt_length(srtp_profile_t profile) +{ + switch (profile) { + case srtp_profile_aes128_cm_sha1_80: + return SRTP_SALT_LEN; + break; + case srtp_profile_aes128_cm_sha1_32: + return SRTP_SALT_LEN; + break; + case srtp_profile_null_sha1_80: + return SRTP_SALT_LEN; + break; + case srtp_profile_aead_aes_128_gcm: + return SRTP_AEAD_SALT_LEN; + break; + case srtp_profile_aead_aes_256_gcm: + return SRTP_AEAD_SALT_LEN; + break; + /* the following profiles are not (yet) supported */ + case srtp_profile_null_sha1_32: + default: + return 0; /* indicate error by returning a zero */ + } +} + +srtp_err_status_t stream_get_protect_trailer_length(srtp_stream_ctx_t *stream, + uint32_t is_rtp, + uint32_t use_mki, + uint32_t mki_index, + uint32_t *length) +{ + srtp_session_keys_t *session_key; + + *length = 0; + + if (use_mki) { + if (mki_index >= stream->num_master_keys) { + return srtp_err_status_bad_mki; + } + session_key = &stream->session_keys[mki_index]; + + *length += session_key->mki_size; + + } else { + session_key = &stream->session_keys[0]; + } + if (is_rtp) { + *length += srtp_auth_get_tag_length(session_key->rtp_auth); + } else { + *length += srtp_auth_get_tag_length(session_key->rtcp_auth); + *length += sizeof(srtcp_trailer_t); + } + + return srtp_err_status_ok; +} + +srtp_err_status_t get_protect_trailer_length(srtp_t session, + uint32_t is_rtp, + uint32_t use_mki, + uint32_t mki_index, + uint32_t *length) +{ + srtp_stream_ctx_t *stream; + + if (session == NULL) { + return srtp_err_status_bad_param; + } + + if (session->stream_template == NULL && session->stream_list == NULL) { + return srtp_err_status_bad_param; + } + + *length = 0; + + stream = session->stream_template; + + if (stream != NULL) { + stream_get_protect_trailer_length(stream, is_rtp, use_mki, mki_index, + length); + } + + stream = session->stream_list; + + while (stream != NULL) { + uint32_t temp_length; + if (stream_get_protect_trailer_length(stream, is_rtp, use_mki, + mki_index, &temp_length) == + srtp_err_status_ok) { + if (temp_length > *length) { + *length = temp_length; + } + } + stream = stream->next; + } + + return srtp_err_status_ok; +} + +srtp_err_status_t srtp_get_protect_trailer_length(srtp_t session, + uint32_t use_mki, + uint32_t mki_index, + uint32_t *length) +{ + return get_protect_trailer_length(session, 1, use_mki, mki_index, length); +} + +srtp_err_status_t srtp_get_protect_rtcp_trailer_length(srtp_t session, + uint32_t use_mki, + uint32_t mki_index, + uint32_t *length) +{ + return get_protect_trailer_length(session, 0, use_mki, mki_index, length); +} + +/* + * SRTP debug interface + */ +srtp_err_status_t srtp_set_debug_module(const char *mod_name, int v) +{ + return srtp_crypto_kernel_set_debug_module(mod_name, v); +} + +srtp_err_status_t srtp_list_debug_modules(void) +{ + return srtp_crypto_kernel_list_debug_modules(); +} + +/* + * srtp_log_handler is a global variable holding a pointer to the + * log handler function; this function is called for any log + * output. + */ + +static srtp_log_handler_func_t *srtp_log_handler = NULL; +static void *srtp_log_handler_data = NULL; + +void srtp_err_handler(srtp_err_reporting_level_t level, const char *msg) +{ + if (srtp_log_handler) { + srtp_log_level_t log_level = srtp_log_level_error; + switch (level) { + case srtp_err_level_error: + log_level = srtp_log_level_error; + break; + case srtp_err_level_warning: + log_level = srtp_log_level_warning; + break; + case srtp_err_level_info: + log_level = srtp_log_level_info; + break; + case srtp_err_level_debug: + log_level = srtp_log_level_debug; + break; + } + + srtp_log_handler(log_level, msg, srtp_log_handler_data); + } +} + +srtp_err_status_t srtp_install_log_handler(srtp_log_handler_func_t func, + void *data) +{ + /* + * note that we accept NULL arguments intentionally - calling this + * function with a NULL arguments removes a log handler that's + * been previously installed + */ + + if (srtp_log_handler) { + srtp_install_err_report_handler(NULL); + } + srtp_log_handler = func; + srtp_log_handler_data = data; + if (srtp_log_handler) { + srtp_install_err_report_handler(srtp_err_handler); + } + return srtp_err_status_ok; +} + +srtp_err_status_t srtp_set_stream_roc(srtp_t session, + uint32_t ssrc, + uint32_t roc) +{ + srtp_stream_t stream; + + stream = srtp_get_stream(session, htonl(ssrc)); + if (stream == NULL) + return srtp_err_status_bad_param; + + stream->pending_roc = roc; + + return srtp_err_status_ok; +} + +srtp_err_status_t srtp_get_stream_roc(srtp_t session, + uint32_t ssrc, + uint32_t *roc) +{ + srtp_stream_t stream; + + stream = srtp_get_stream(session, htonl(ssrc)); + if (stream == NULL) + return srtp_err_status_bad_param; + + *roc = srtp_rdbx_get_roc(&stream->rtp_rdbx); + + return srtp_err_status_ok; +} |