diff options
Diffstat (limited to 'security/keys/encrypted-keys/encrypted.c')
| -rw-r--r-- | security/keys/encrypted-keys/encrypted.c | 1010 |
1 files changed, 1010 insertions, 0 deletions
diff --git a/security/keys/encrypted-keys/encrypted.c b/security/keys/encrypted-keys/encrypted.c new file mode 100644 index 000000000..192e531c1 --- /dev/null +++ b/security/keys/encrypted-keys/encrypted.c @@ -0,0 +1,1010 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (C) 2010 IBM Corporation + * Copyright (C) 2010 Politecnico di Torino, Italy + * TORSEC group -- https://security.polito.it + * + * Authors: + * Mimi Zohar <zohar@us.ibm.com> + * Roberto Sassu <roberto.sassu@polito.it> + * + * See Documentation/security/keys/trusted-encrypted.rst + */ + +#include <linux/uaccess.h> +#include <linux/module.h> +#include <linux/init.h> +#include <linux/slab.h> +#include <linux/parser.h> +#include <linux/string.h> +#include <linux/err.h> +#include <keys/user-type.h> +#include <keys/trusted-type.h> +#include <keys/encrypted-type.h> +#include <linux/key-type.h> +#include <linux/random.h> +#include <linux/rcupdate.h> +#include <linux/scatterlist.h> +#include <linux/ctype.h> +#include <crypto/aes.h> +#include <crypto/algapi.h> +#include <crypto/hash.h> +#include <crypto/sha.h> +#include <crypto/skcipher.h> + +#include "encrypted.h" +#include "ecryptfs_format.h" + +static const char KEY_TRUSTED_PREFIX[] = "trusted:"; +static const char KEY_USER_PREFIX[] = "user:"; +static const char hash_alg[] = "sha256"; +static const char hmac_alg[] = "hmac(sha256)"; +static const char blkcipher_alg[] = "cbc(aes)"; +static const char key_format_default[] = "default"; +static const char key_format_ecryptfs[] = "ecryptfs"; +static const char key_format_enc32[] = "enc32"; +static unsigned int ivsize; +static int blksize; + +#define KEY_TRUSTED_PREFIX_LEN (sizeof (KEY_TRUSTED_PREFIX) - 1) +#define KEY_USER_PREFIX_LEN (sizeof (KEY_USER_PREFIX) - 1) +#define KEY_ECRYPTFS_DESC_LEN 16 +#define HASH_SIZE SHA256_DIGEST_SIZE +#define MAX_DATA_SIZE 4096 +#define MIN_DATA_SIZE 20 +#define KEY_ENC32_PAYLOAD_LEN 32 + +static struct crypto_shash *hash_tfm; + +enum { + Opt_new, Opt_load, Opt_update, Opt_err +}; + +enum { + Opt_default, Opt_ecryptfs, Opt_enc32, Opt_error +}; + +static const match_table_t key_format_tokens = { + {Opt_default, "default"}, + {Opt_ecryptfs, "ecryptfs"}, + {Opt_enc32, "enc32"}, + {Opt_error, NULL} +}; + +static const match_table_t key_tokens = { + {Opt_new, "new"}, + {Opt_load, "load"}, + {Opt_update, "update"}, + {Opt_err, NULL} +}; + +static int aes_get_sizes(void) +{ + struct crypto_skcipher *tfm; + + tfm = crypto_alloc_skcipher(blkcipher_alg, 0, CRYPTO_ALG_ASYNC); + if (IS_ERR(tfm)) { + pr_err("encrypted_key: failed to alloc_cipher (%ld)\n", + PTR_ERR(tfm)); + return PTR_ERR(tfm); + } + ivsize = crypto_skcipher_ivsize(tfm); + blksize = crypto_skcipher_blocksize(tfm); + crypto_free_skcipher(tfm); + return 0; +} + +/* + * valid_ecryptfs_desc - verify the description of a new/loaded encrypted key + * + * The description of a encrypted key with format 'ecryptfs' must contain + * exactly 16 hexadecimal characters. + * + */ +static int valid_ecryptfs_desc(const char *ecryptfs_desc) +{ + int i; + + if (strlen(ecryptfs_desc) != KEY_ECRYPTFS_DESC_LEN) { + pr_err("encrypted_key: key description must be %d hexadecimal " + "characters long\n", KEY_ECRYPTFS_DESC_LEN); + return -EINVAL; + } + + for (i = 0; i < KEY_ECRYPTFS_DESC_LEN; i++) { + if (!isxdigit(ecryptfs_desc[i])) { + pr_err("encrypted_key: key description must contain " + "only hexadecimal characters\n"); + return -EINVAL; + } + } + + return 0; +} + +/* + * valid_master_desc - verify the 'key-type:desc' of a new/updated master-key + * + * key-type:= "trusted:" | "user:" + * desc:= master-key description + * + * Verify that 'key-type' is valid and that 'desc' exists. On key update, + * only the master key description is permitted to change, not the key-type. + * The key-type remains constant. + * + * On success returns 0, otherwise -EINVAL. + */ +static int valid_master_desc(const char *new_desc, const char *orig_desc) +{ + int prefix_len; + + if (!strncmp(new_desc, KEY_TRUSTED_PREFIX, KEY_TRUSTED_PREFIX_LEN)) + prefix_len = KEY_TRUSTED_PREFIX_LEN; + else if (!strncmp(new_desc, KEY_USER_PREFIX, KEY_USER_PREFIX_LEN)) + prefix_len = KEY_USER_PREFIX_LEN; + else + return -EINVAL; + + if (!new_desc[prefix_len]) + return -EINVAL; + + if (orig_desc && strncmp(new_desc, orig_desc, prefix_len)) + return -EINVAL; + + return 0; +} + +/* + * datablob_parse - parse the keyctl data + * + * datablob format: + * new [<format>] <master-key name> <decrypted data length> + * load [<format>] <master-key name> <decrypted data length> + * <encrypted iv + data> + * update <new-master-key name> + * + * Tokenizes a copy of the keyctl data, returning a pointer to each token, + * which is null terminated. + * + * On success returns 0, otherwise -EINVAL. + */ +static int datablob_parse(char *datablob, const char **format, + char **master_desc, char **decrypted_datalen, + char **hex_encoded_iv) +{ + substring_t args[MAX_OPT_ARGS]; + int ret = -EINVAL; + int key_cmd; + int key_format; + char *p, *keyword; + + keyword = strsep(&datablob, " \t"); + if (!keyword) { + pr_info("encrypted_key: insufficient parameters specified\n"); + return ret; + } + key_cmd = match_token(keyword, key_tokens, args); + + /* Get optional format: default | ecryptfs */ + p = strsep(&datablob, " \t"); + if (!p) { + pr_err("encrypted_key: insufficient parameters specified\n"); + return ret; + } + + key_format = match_token(p, key_format_tokens, args); + switch (key_format) { + case Opt_ecryptfs: + case Opt_enc32: + case Opt_default: + *format = p; + *master_desc = strsep(&datablob, " \t"); + break; + case Opt_error: + *master_desc = p; + break; + } + + if (!*master_desc) { + pr_info("encrypted_key: master key parameter is missing\n"); + goto out; + } + + if (valid_master_desc(*master_desc, NULL) < 0) { + pr_info("encrypted_key: master key parameter \'%s\' " + "is invalid\n", *master_desc); + goto out; + } + + if (decrypted_datalen) { + *decrypted_datalen = strsep(&datablob, " \t"); + if (!*decrypted_datalen) { + pr_info("encrypted_key: keylen parameter is missing\n"); + goto out; + } + } + + switch (key_cmd) { + case Opt_new: + if (!decrypted_datalen) { + pr_info("encrypted_key: keyword \'%s\' not allowed " + "when called from .update method\n", keyword); + break; + } + ret = 0; + break; + case Opt_load: + if (!decrypted_datalen) { + pr_info("encrypted_key: keyword \'%s\' not allowed " + "when called from .update method\n", keyword); + break; + } + *hex_encoded_iv = strsep(&datablob, " \t"); + if (!*hex_encoded_iv) { + pr_info("encrypted_key: hex blob is missing\n"); + break; + } + ret = 0; + break; + case Opt_update: + if (decrypted_datalen) { + pr_info("encrypted_key: keyword \'%s\' not allowed " + "when called from .instantiate method\n", + keyword); + break; + } + ret = 0; + break; + case Opt_err: + pr_info("encrypted_key: keyword \'%s\' not recognized\n", + keyword); + break; + } +out: + return ret; +} + +/* + * datablob_format - format as an ascii string, before copying to userspace + */ +static char *datablob_format(struct encrypted_key_payload *epayload, + size_t asciiblob_len) +{ + char *ascii_buf, *bufp; + u8 *iv = epayload->iv; + int len; + int i; + + ascii_buf = kmalloc(asciiblob_len + 1, GFP_KERNEL); + if (!ascii_buf) + goto out; + + ascii_buf[asciiblob_len] = '\0'; + + /* copy datablob master_desc and datalen strings */ + len = sprintf(ascii_buf, "%s %s %s ", epayload->format, + epayload->master_desc, epayload->datalen); + + /* convert the hex encoded iv, encrypted-data and HMAC to ascii */ + bufp = &ascii_buf[len]; + for (i = 0; i < (asciiblob_len - len) / 2; i++) + bufp = hex_byte_pack(bufp, iv[i]); +out: + return ascii_buf; +} + +/* + * request_user_key - request the user key + * + * Use a user provided key to encrypt/decrypt an encrypted-key. + */ +static struct key *request_user_key(const char *master_desc, const u8 **master_key, + size_t *master_keylen) +{ + const struct user_key_payload *upayload; + struct key *ukey; + + ukey = request_key(&key_type_user, master_desc, NULL); + if (IS_ERR(ukey)) + goto error; + + down_read(&ukey->sem); + upayload = user_key_payload_locked(ukey); + if (!upayload) { + /* key was revoked before we acquired its semaphore */ + up_read(&ukey->sem); + key_put(ukey); + ukey = ERR_PTR(-EKEYREVOKED); + goto error; + } + *master_key = upayload->data; + *master_keylen = upayload->datalen; +error: + return ukey; +} + +static int calc_hmac(u8 *digest, const u8 *key, unsigned int keylen, + const u8 *buf, unsigned int buflen) +{ + struct crypto_shash *tfm; + int err; + + tfm = crypto_alloc_shash(hmac_alg, 0, 0); + if (IS_ERR(tfm)) { + pr_err("encrypted_key: can't alloc %s transform: %ld\n", + hmac_alg, PTR_ERR(tfm)); + return PTR_ERR(tfm); + } + + err = crypto_shash_setkey(tfm, key, keylen); + if (!err) + err = crypto_shash_tfm_digest(tfm, buf, buflen, digest); + crypto_free_shash(tfm); + return err; +} + +enum derived_key_type { ENC_KEY, AUTH_KEY }; + +/* Derive authentication/encryption key from trusted key */ +static int get_derived_key(u8 *derived_key, enum derived_key_type key_type, + const u8 *master_key, size_t master_keylen) +{ + u8 *derived_buf; + unsigned int derived_buf_len; + int ret; + + derived_buf_len = strlen("AUTH_KEY") + 1 + master_keylen; + if (derived_buf_len < HASH_SIZE) + derived_buf_len = HASH_SIZE; + + derived_buf = kzalloc(derived_buf_len, GFP_KERNEL); + if (!derived_buf) + return -ENOMEM; + + if (key_type) + strcpy(derived_buf, "AUTH_KEY"); + else + strcpy(derived_buf, "ENC_KEY"); + + memcpy(derived_buf + strlen(derived_buf) + 1, master_key, + master_keylen); + ret = crypto_shash_tfm_digest(hash_tfm, derived_buf, derived_buf_len, + derived_key); + kfree_sensitive(derived_buf); + return ret; +} + +static struct skcipher_request *init_skcipher_req(const u8 *key, + unsigned int key_len) +{ + struct skcipher_request *req; + struct crypto_skcipher *tfm; + int ret; + + tfm = crypto_alloc_skcipher(blkcipher_alg, 0, CRYPTO_ALG_ASYNC); + if (IS_ERR(tfm)) { + pr_err("encrypted_key: failed to load %s transform (%ld)\n", + blkcipher_alg, PTR_ERR(tfm)); + return ERR_CAST(tfm); + } + + ret = crypto_skcipher_setkey(tfm, key, key_len); + if (ret < 0) { + pr_err("encrypted_key: failed to setkey (%d)\n", ret); + crypto_free_skcipher(tfm); + return ERR_PTR(ret); + } + + req = skcipher_request_alloc(tfm, GFP_KERNEL); + if (!req) { + pr_err("encrypted_key: failed to allocate request for %s\n", + blkcipher_alg); + crypto_free_skcipher(tfm); + return ERR_PTR(-ENOMEM); + } + + skcipher_request_set_callback(req, 0, NULL, NULL); + return req; +} + +static struct key *request_master_key(struct encrypted_key_payload *epayload, + const u8 **master_key, size_t *master_keylen) +{ + struct key *mkey = ERR_PTR(-EINVAL); + + if (!strncmp(epayload->master_desc, KEY_TRUSTED_PREFIX, + KEY_TRUSTED_PREFIX_LEN)) { + mkey = request_trusted_key(epayload->master_desc + + KEY_TRUSTED_PREFIX_LEN, + master_key, master_keylen); + } else if (!strncmp(epayload->master_desc, KEY_USER_PREFIX, + KEY_USER_PREFIX_LEN)) { + mkey = request_user_key(epayload->master_desc + + KEY_USER_PREFIX_LEN, + master_key, master_keylen); + } else + goto out; + + if (IS_ERR(mkey)) { + int ret = PTR_ERR(mkey); + + if (ret == -ENOTSUPP) + pr_info("encrypted_key: key %s not supported", + epayload->master_desc); + else + pr_info("encrypted_key: key %s not found", + epayload->master_desc); + goto out; + } + + dump_master_key(*master_key, *master_keylen); +out: + return mkey; +} + +/* Before returning data to userspace, encrypt decrypted data. */ +static int derived_key_encrypt(struct encrypted_key_payload *epayload, + const u8 *derived_key, + unsigned int derived_keylen) +{ + struct scatterlist sg_in[2]; + struct scatterlist sg_out[1]; + struct crypto_skcipher *tfm; + struct skcipher_request *req; + unsigned int encrypted_datalen; + u8 iv[AES_BLOCK_SIZE]; + int ret; + + encrypted_datalen = roundup(epayload->decrypted_datalen, blksize); + + req = init_skcipher_req(derived_key, derived_keylen); + ret = PTR_ERR(req); + if (IS_ERR(req)) + goto out; + dump_decrypted_data(epayload); + + sg_init_table(sg_in, 2); + sg_set_buf(&sg_in[0], epayload->decrypted_data, + epayload->decrypted_datalen); + sg_set_page(&sg_in[1], ZERO_PAGE(0), AES_BLOCK_SIZE, 0); + + sg_init_table(sg_out, 1); + sg_set_buf(sg_out, epayload->encrypted_data, encrypted_datalen); + + memcpy(iv, epayload->iv, sizeof(iv)); + skcipher_request_set_crypt(req, sg_in, sg_out, encrypted_datalen, iv); + ret = crypto_skcipher_encrypt(req); + tfm = crypto_skcipher_reqtfm(req); + skcipher_request_free(req); + crypto_free_skcipher(tfm); + if (ret < 0) + pr_err("encrypted_key: failed to encrypt (%d)\n", ret); + else + dump_encrypted_data(epayload, encrypted_datalen); +out: + return ret; +} + +static int datablob_hmac_append(struct encrypted_key_payload *epayload, + const u8 *master_key, size_t master_keylen) +{ + u8 derived_key[HASH_SIZE]; + u8 *digest; + int ret; + + ret = get_derived_key(derived_key, AUTH_KEY, master_key, master_keylen); + if (ret < 0) + goto out; + + digest = epayload->format + epayload->datablob_len; + ret = calc_hmac(digest, derived_key, sizeof derived_key, + epayload->format, epayload->datablob_len); + if (!ret) + dump_hmac(NULL, digest, HASH_SIZE); +out: + memzero_explicit(derived_key, sizeof(derived_key)); + return ret; +} + +/* verify HMAC before decrypting encrypted key */ +static int datablob_hmac_verify(struct encrypted_key_payload *epayload, + const u8 *format, const u8 *master_key, + size_t master_keylen) +{ + u8 derived_key[HASH_SIZE]; + u8 digest[HASH_SIZE]; + int ret; + char *p; + unsigned short len; + + ret = get_derived_key(derived_key, AUTH_KEY, master_key, master_keylen); + if (ret < 0) + goto out; + + len = epayload->datablob_len; + if (!format) { + p = epayload->master_desc; + len -= strlen(epayload->format) + 1; + } else + p = epayload->format; + + ret = calc_hmac(digest, derived_key, sizeof derived_key, p, len); + if (ret < 0) + goto out; + ret = crypto_memneq(digest, epayload->format + epayload->datablob_len, + sizeof(digest)); + if (ret) { + ret = -EINVAL; + dump_hmac("datablob", + epayload->format + epayload->datablob_len, + HASH_SIZE); + dump_hmac("calc", digest, HASH_SIZE); + } +out: + memzero_explicit(derived_key, sizeof(derived_key)); + return ret; +} + +static int derived_key_decrypt(struct encrypted_key_payload *epayload, + const u8 *derived_key, + unsigned int derived_keylen) +{ + struct scatterlist sg_in[1]; + struct scatterlist sg_out[2]; + struct crypto_skcipher *tfm; + struct skcipher_request *req; + unsigned int encrypted_datalen; + u8 iv[AES_BLOCK_SIZE]; + u8 *pad; + int ret; + + /* Throwaway buffer to hold the unused zero padding at the end */ + pad = kmalloc(AES_BLOCK_SIZE, GFP_KERNEL); + if (!pad) + return -ENOMEM; + + encrypted_datalen = roundup(epayload->decrypted_datalen, blksize); + req = init_skcipher_req(derived_key, derived_keylen); + ret = PTR_ERR(req); + if (IS_ERR(req)) + goto out; + dump_encrypted_data(epayload, encrypted_datalen); + + sg_init_table(sg_in, 1); + sg_init_table(sg_out, 2); + sg_set_buf(sg_in, epayload->encrypted_data, encrypted_datalen); + sg_set_buf(&sg_out[0], epayload->decrypted_data, + epayload->decrypted_datalen); + sg_set_buf(&sg_out[1], pad, AES_BLOCK_SIZE); + + memcpy(iv, epayload->iv, sizeof(iv)); + skcipher_request_set_crypt(req, sg_in, sg_out, encrypted_datalen, iv); + ret = crypto_skcipher_decrypt(req); + tfm = crypto_skcipher_reqtfm(req); + skcipher_request_free(req); + crypto_free_skcipher(tfm); + if (ret < 0) + goto out; + dump_decrypted_data(epayload); +out: + kfree(pad); + return ret; +} + +/* Allocate memory for decrypted key and datablob. */ +static struct encrypted_key_payload *encrypted_key_alloc(struct key *key, + const char *format, + const char *master_desc, + const char *datalen) +{ + struct encrypted_key_payload *epayload = NULL; + unsigned short datablob_len; + unsigned short decrypted_datalen; + unsigned short payload_datalen; + unsigned int encrypted_datalen; + unsigned int format_len; + long dlen; + int ret; + + ret = kstrtol(datalen, 10, &dlen); + if (ret < 0 || dlen < MIN_DATA_SIZE || dlen > MAX_DATA_SIZE) + return ERR_PTR(-EINVAL); + + format_len = (!format) ? strlen(key_format_default) : strlen(format); + decrypted_datalen = dlen; + payload_datalen = decrypted_datalen; + if (format) { + if (!strcmp(format, key_format_ecryptfs)) { + if (dlen != ECRYPTFS_MAX_KEY_BYTES) { + pr_err("encrypted_key: keylen for the ecryptfs format must be equal to %d bytes\n", + ECRYPTFS_MAX_KEY_BYTES); + return ERR_PTR(-EINVAL); + } + decrypted_datalen = ECRYPTFS_MAX_KEY_BYTES; + payload_datalen = sizeof(struct ecryptfs_auth_tok); + } else if (!strcmp(format, key_format_enc32)) { + if (decrypted_datalen != KEY_ENC32_PAYLOAD_LEN) { + pr_err("encrypted_key: enc32 key payload incorrect length: %d\n", + decrypted_datalen); + return ERR_PTR(-EINVAL); + } + } + } + + encrypted_datalen = roundup(decrypted_datalen, blksize); + + datablob_len = format_len + 1 + strlen(master_desc) + 1 + + strlen(datalen) + 1 + ivsize + 1 + encrypted_datalen; + + ret = key_payload_reserve(key, payload_datalen + datablob_len + + HASH_SIZE + 1); + if (ret < 0) + return ERR_PTR(ret); + + epayload = kzalloc(sizeof(*epayload) + payload_datalen + + datablob_len + HASH_SIZE + 1, GFP_KERNEL); + if (!epayload) + return ERR_PTR(-ENOMEM); + + epayload->payload_datalen = payload_datalen; + epayload->decrypted_datalen = decrypted_datalen; + epayload->datablob_len = datablob_len; + return epayload; +} + +static int encrypted_key_decrypt(struct encrypted_key_payload *epayload, + const char *format, const char *hex_encoded_iv) +{ + struct key *mkey; + u8 derived_key[HASH_SIZE]; + const u8 *master_key; + u8 *hmac; + const char *hex_encoded_data; + unsigned int encrypted_datalen; + size_t master_keylen; + size_t asciilen; + int ret; + + encrypted_datalen = roundup(epayload->decrypted_datalen, blksize); + asciilen = (ivsize + 1 + encrypted_datalen + HASH_SIZE) * 2; + if (strlen(hex_encoded_iv) != asciilen) + return -EINVAL; + + hex_encoded_data = hex_encoded_iv + (2 * ivsize) + 2; + ret = hex2bin(epayload->iv, hex_encoded_iv, ivsize); + if (ret < 0) + return -EINVAL; + ret = hex2bin(epayload->encrypted_data, hex_encoded_data, + encrypted_datalen); + if (ret < 0) + return -EINVAL; + + hmac = epayload->format + epayload->datablob_len; + ret = hex2bin(hmac, hex_encoded_data + (encrypted_datalen * 2), + HASH_SIZE); + if (ret < 0) + return -EINVAL; + + mkey = request_master_key(epayload, &master_key, &master_keylen); + if (IS_ERR(mkey)) + return PTR_ERR(mkey); + + ret = datablob_hmac_verify(epayload, format, master_key, master_keylen); + if (ret < 0) { + pr_err("encrypted_key: bad hmac (%d)\n", ret); + goto out; + } + + ret = get_derived_key(derived_key, ENC_KEY, master_key, master_keylen); + if (ret < 0) + goto out; + + ret = derived_key_decrypt(epayload, derived_key, sizeof derived_key); + if (ret < 0) + pr_err("encrypted_key: failed to decrypt key (%d)\n", ret); +out: + up_read(&mkey->sem); + key_put(mkey); + memzero_explicit(derived_key, sizeof(derived_key)); + return ret; +} + +static void __ekey_init(struct encrypted_key_payload *epayload, + const char *format, const char *master_desc, + const char *datalen) +{ + unsigned int format_len; + + format_len = (!format) ? strlen(key_format_default) : strlen(format); + epayload->format = epayload->payload_data + epayload->payload_datalen; + epayload->master_desc = epayload->format + format_len + 1; + epayload->datalen = epayload->master_desc + strlen(master_desc) + 1; + epayload->iv = epayload->datalen + strlen(datalen) + 1; + epayload->encrypted_data = epayload->iv + ivsize + 1; + epayload->decrypted_data = epayload->payload_data; + + if (!format) + memcpy(epayload->format, key_format_default, format_len); + else { + if (!strcmp(format, key_format_ecryptfs)) + epayload->decrypted_data = + ecryptfs_get_auth_tok_key((struct ecryptfs_auth_tok *)epayload->payload_data); + + memcpy(epayload->format, format, format_len); + } + + memcpy(epayload->master_desc, master_desc, strlen(master_desc)); + memcpy(epayload->datalen, datalen, strlen(datalen)); +} + +/* + * encrypted_init - initialize an encrypted key + * + * For a new key, use a random number for both the iv and data + * itself. For an old key, decrypt the hex encoded data. + */ +static int encrypted_init(struct encrypted_key_payload *epayload, + const char *key_desc, const char *format, + const char *master_desc, const char *datalen, + const char *hex_encoded_iv) +{ + int ret = 0; + + if (format && !strcmp(format, key_format_ecryptfs)) { + ret = valid_ecryptfs_desc(key_desc); + if (ret < 0) + return ret; + + ecryptfs_fill_auth_tok((struct ecryptfs_auth_tok *)epayload->payload_data, + key_desc); + } + + __ekey_init(epayload, format, master_desc, datalen); + if (!hex_encoded_iv) { + get_random_bytes(epayload->iv, ivsize); + + get_random_bytes(epayload->decrypted_data, + epayload->decrypted_datalen); + } else + ret = encrypted_key_decrypt(epayload, format, hex_encoded_iv); + return ret; +} + +/* + * encrypted_instantiate - instantiate an encrypted key + * + * Decrypt an existing encrypted datablob or create a new encrypted key + * based on a kernel random number. + * + * On success, return 0. Otherwise return errno. + */ +static int encrypted_instantiate(struct key *key, + struct key_preparsed_payload *prep) +{ + struct encrypted_key_payload *epayload = NULL; + char *datablob = NULL; + const char *format = NULL; + char *master_desc = NULL; + char *decrypted_datalen = NULL; + char *hex_encoded_iv = NULL; + size_t datalen = prep->datalen; + int ret; + + if (datalen <= 0 || datalen > 32767 || !prep->data) + return -EINVAL; + + datablob = kmalloc(datalen + 1, GFP_KERNEL); + if (!datablob) + return -ENOMEM; + datablob[datalen] = 0; + memcpy(datablob, prep->data, datalen); + ret = datablob_parse(datablob, &format, &master_desc, + &decrypted_datalen, &hex_encoded_iv); + if (ret < 0) + goto out; + + epayload = encrypted_key_alloc(key, format, master_desc, + decrypted_datalen); + if (IS_ERR(epayload)) { + ret = PTR_ERR(epayload); + goto out; + } + ret = encrypted_init(epayload, key->description, format, master_desc, + decrypted_datalen, hex_encoded_iv); + if (ret < 0) { + kfree_sensitive(epayload); + goto out; + } + + rcu_assign_keypointer(key, epayload); +out: + kfree_sensitive(datablob); + return ret; +} + +static void encrypted_rcu_free(struct rcu_head *rcu) +{ + struct encrypted_key_payload *epayload; + + epayload = container_of(rcu, struct encrypted_key_payload, rcu); + kfree_sensitive(epayload); +} + +/* + * encrypted_update - update the master key description + * + * Change the master key description for an existing encrypted key. + * The next read will return an encrypted datablob using the new + * master key description. + * + * On success, return 0. Otherwise return errno. + */ +static int encrypted_update(struct key *key, struct key_preparsed_payload *prep) +{ + struct encrypted_key_payload *epayload = key->payload.data[0]; + struct encrypted_key_payload *new_epayload; + char *buf; + char *new_master_desc = NULL; + const char *format = NULL; + size_t datalen = prep->datalen; + int ret = 0; + + if (key_is_negative(key)) + return -ENOKEY; + if (datalen <= 0 || datalen > 32767 || !prep->data) + return -EINVAL; + + buf = kmalloc(datalen + 1, GFP_KERNEL); + if (!buf) + return -ENOMEM; + + buf[datalen] = 0; + memcpy(buf, prep->data, datalen); + ret = datablob_parse(buf, &format, &new_master_desc, NULL, NULL); + if (ret < 0) + goto out; + + ret = valid_master_desc(new_master_desc, epayload->master_desc); + if (ret < 0) + goto out; + + new_epayload = encrypted_key_alloc(key, epayload->format, + new_master_desc, epayload->datalen); + if (IS_ERR(new_epayload)) { + ret = PTR_ERR(new_epayload); + goto out; + } + + __ekey_init(new_epayload, epayload->format, new_master_desc, + epayload->datalen); + + memcpy(new_epayload->iv, epayload->iv, ivsize); + memcpy(new_epayload->payload_data, epayload->payload_data, + epayload->payload_datalen); + + rcu_assign_keypointer(key, new_epayload); + call_rcu(&epayload->rcu, encrypted_rcu_free); +out: + kfree_sensitive(buf); + return ret; +} + +/* + * encrypted_read - format and copy out the encrypted data + * + * The resulting datablob format is: + * <master-key name> <decrypted data length> <encrypted iv> <encrypted data> + * + * On success, return to userspace the encrypted key datablob size. + */ +static long encrypted_read(const struct key *key, char *buffer, + size_t buflen) +{ + struct encrypted_key_payload *epayload; + struct key *mkey; + const u8 *master_key; + size_t master_keylen; + char derived_key[HASH_SIZE]; + char *ascii_buf; + size_t asciiblob_len; + int ret; + + epayload = dereference_key_locked(key); + + /* returns the hex encoded iv, encrypted-data, and hmac as ascii */ + asciiblob_len = epayload->datablob_len + ivsize + 1 + + roundup(epayload->decrypted_datalen, blksize) + + (HASH_SIZE * 2); + + if (!buffer || buflen < asciiblob_len) + return asciiblob_len; + + mkey = request_master_key(epayload, &master_key, &master_keylen); + if (IS_ERR(mkey)) + return PTR_ERR(mkey); + + ret = get_derived_key(derived_key, ENC_KEY, master_key, master_keylen); + if (ret < 0) + goto out; + + ret = derived_key_encrypt(epayload, derived_key, sizeof derived_key); + if (ret < 0) + goto out; + + ret = datablob_hmac_append(epayload, master_key, master_keylen); + if (ret < 0) + goto out; + + ascii_buf = datablob_format(epayload, asciiblob_len); + if (!ascii_buf) { + ret = -ENOMEM; + goto out; + } + + up_read(&mkey->sem); + key_put(mkey); + memzero_explicit(derived_key, sizeof(derived_key)); + + memcpy(buffer, ascii_buf, asciiblob_len); + kfree_sensitive(ascii_buf); + + return asciiblob_len; +out: + up_read(&mkey->sem); + key_put(mkey); + memzero_explicit(derived_key, sizeof(derived_key)); + return ret; +} + +/* + * encrypted_destroy - clear and free the key's payload + */ +static void encrypted_destroy(struct key *key) +{ + kfree_sensitive(key->payload.data[0]); +} + +struct key_type key_type_encrypted = { + .name = "encrypted", + .instantiate = encrypted_instantiate, + .update = encrypted_update, + .destroy = encrypted_destroy, + .describe = user_describe, + .read = encrypted_read, +}; +EXPORT_SYMBOL_GPL(key_type_encrypted); + +static int __init init_encrypted(void) +{ + int ret; + + hash_tfm = crypto_alloc_shash(hash_alg, 0, 0); + if (IS_ERR(hash_tfm)) { + pr_err("encrypted_key: can't allocate %s transform: %ld\n", + hash_alg, PTR_ERR(hash_tfm)); + return PTR_ERR(hash_tfm); + } + + ret = aes_get_sizes(); + if (ret < 0) + goto out; + ret = register_key_type(&key_type_encrypted); + if (ret < 0) + goto out; + return 0; +out: + crypto_free_shash(hash_tfm); + return ret; + +} + +static void __exit cleanup_encrypted(void) +{ + crypto_free_shash(hash_tfm); + unregister_key_type(&key_type_encrypted); +} + +late_initcall(init_encrypted); +module_exit(cleanup_encrypted); + +MODULE_LICENSE("GPL"); |