diff options
Diffstat (limited to 'ssh-dss.c')
| -rw-r--r-- | ssh-dss.c | 457 |
1 files changed, 457 insertions, 0 deletions
diff --git a/ssh-dss.c b/ssh-dss.c new file mode 100644 index 0000000..2ea0c0a --- /dev/null +++ b/ssh-dss.c @@ -0,0 +1,457 @@ +/* $OpenBSD: ssh-dss.c,v 1.48 2022/10/28 00:44:44 djm Exp $ */ +/* + * Copyright (c) 2000 Markus Friedl. All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. 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. + * + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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. + */ + +#include "includes.h" + +#ifdef WITH_OPENSSL + +#include <sys/types.h> + +#include <openssl/bn.h> +#include <openssl/dsa.h> +#include <openssl/evp.h> + +#include <stdarg.h> +#include <string.h> + +#include "sshbuf.h" +#include "compat.h" +#include "ssherr.h" +#include "digest.h" +#define SSHKEY_INTERNAL +#include "sshkey.h" + +#include "openbsd-compat/openssl-compat.h" + +#define INTBLOB_LEN 20 +#define SIGBLOB_LEN (2*INTBLOB_LEN) + +static u_int +ssh_dss_size(const struct sshkey *key) +{ + const BIGNUM *dsa_p; + + if (key->dsa == NULL) + return 0; + DSA_get0_pqg(key->dsa, &dsa_p, NULL, NULL); + return BN_num_bits(dsa_p); +} + +static int +ssh_dss_alloc(struct sshkey *k) +{ + if ((k->dsa = DSA_new()) == NULL) + return SSH_ERR_ALLOC_FAIL; + return 0; +} + +static void +ssh_dss_cleanup(struct sshkey *k) +{ + DSA_free(k->dsa); + k->dsa = NULL; +} + +static int +ssh_dss_equal(const struct sshkey *a, const struct sshkey *b) +{ + const BIGNUM *dsa_p_a, *dsa_q_a, *dsa_g_a, *dsa_pub_key_a; + const BIGNUM *dsa_p_b, *dsa_q_b, *dsa_g_b, *dsa_pub_key_b; + + if (a->dsa == NULL || b->dsa == NULL) + return 0; + DSA_get0_pqg(a->dsa, &dsa_p_a, &dsa_q_a, &dsa_g_a); + DSA_get0_pqg(b->dsa, &dsa_p_b, &dsa_q_b, &dsa_g_b); + DSA_get0_key(a->dsa, &dsa_pub_key_a, NULL); + DSA_get0_key(b->dsa, &dsa_pub_key_b, NULL); + if (dsa_p_a == NULL || dsa_p_b == NULL || + dsa_q_a == NULL || dsa_q_b == NULL || + dsa_g_a == NULL || dsa_g_b == NULL || + dsa_pub_key_a == NULL || dsa_pub_key_b == NULL) + return 0; + if (BN_cmp(dsa_p_a, dsa_p_b) != 0) + return 0; + if (BN_cmp(dsa_q_a, dsa_q_b) != 0) + return 0; + if (BN_cmp(dsa_g_a, dsa_g_b) != 0) + return 0; + if (BN_cmp(dsa_pub_key_a, dsa_pub_key_b) != 0) + return 0; + return 1; +} + +static int +ssh_dss_serialize_public(const struct sshkey *key, struct sshbuf *b, + enum sshkey_serialize_rep opts) +{ + int r; + const BIGNUM *dsa_p, *dsa_q, *dsa_g, *dsa_pub_key; + + if (key->dsa == NULL) + return SSH_ERR_INVALID_ARGUMENT; + DSA_get0_pqg(key->dsa, &dsa_p, &dsa_q, &dsa_g); + DSA_get0_key(key->dsa, &dsa_pub_key, NULL); + if (dsa_p == NULL || dsa_q == NULL || + dsa_g == NULL || dsa_pub_key == NULL) + return SSH_ERR_INTERNAL_ERROR; + if ((r = sshbuf_put_bignum2(b, dsa_p)) != 0 || + (r = sshbuf_put_bignum2(b, dsa_q)) != 0 || + (r = sshbuf_put_bignum2(b, dsa_g)) != 0 || + (r = sshbuf_put_bignum2(b, dsa_pub_key)) != 0) + return r; + + return 0; +} + +static int +ssh_dss_serialize_private(const struct sshkey *key, struct sshbuf *b, + enum sshkey_serialize_rep opts) +{ + int r; + const BIGNUM *dsa_priv_key; + + DSA_get0_key(key->dsa, NULL, &dsa_priv_key); + if (!sshkey_is_cert(key)) { + if ((r = ssh_dss_serialize_public(key, b, opts)) != 0) + return r; + } + if ((r = sshbuf_put_bignum2(b, dsa_priv_key)) != 0) + return r; + + return 0; +} + +static int +ssh_dss_generate(struct sshkey *k, int bits) +{ + DSA *private; + + if (bits != 1024) + return SSH_ERR_KEY_LENGTH; + if ((private = DSA_new()) == NULL) + return SSH_ERR_ALLOC_FAIL; + if (!DSA_generate_parameters_ex(private, bits, NULL, 0, NULL, + NULL, NULL) || !DSA_generate_key(private)) { + DSA_free(private); + return SSH_ERR_LIBCRYPTO_ERROR; + } + k->dsa = private; + return 0; +} + +static int +ssh_dss_copy_public(const struct sshkey *from, struct sshkey *to) +{ + const BIGNUM *dsa_p, *dsa_q, *dsa_g, *dsa_pub_key; + BIGNUM *dsa_p_dup = NULL, *dsa_q_dup = NULL, *dsa_g_dup = NULL; + BIGNUM *dsa_pub_key_dup = NULL; + int r = SSH_ERR_INTERNAL_ERROR; + + DSA_get0_pqg(from->dsa, &dsa_p, &dsa_q, &dsa_g); + DSA_get0_key(from->dsa, &dsa_pub_key, NULL); + if ((dsa_p_dup = BN_dup(dsa_p)) == NULL || + (dsa_q_dup = BN_dup(dsa_q)) == NULL || + (dsa_g_dup = BN_dup(dsa_g)) == NULL || + (dsa_pub_key_dup = BN_dup(dsa_pub_key)) == NULL) { + r = SSH_ERR_ALLOC_FAIL; + goto out; + } + if (!DSA_set0_pqg(to->dsa, dsa_p_dup, dsa_q_dup, dsa_g_dup)) { + r = SSH_ERR_LIBCRYPTO_ERROR; + goto out; + } + dsa_p_dup = dsa_q_dup = dsa_g_dup = NULL; /* transferred */ + if (!DSA_set0_key(to->dsa, dsa_pub_key_dup, NULL)) { + r = SSH_ERR_LIBCRYPTO_ERROR; + goto out; + } + dsa_pub_key_dup = NULL; /* transferred */ + /* success */ + r = 0; + out: + BN_clear_free(dsa_p_dup); + BN_clear_free(dsa_q_dup); + BN_clear_free(dsa_g_dup); + BN_clear_free(dsa_pub_key_dup); + return r; +} + +static int +ssh_dss_deserialize_public(const char *ktype, struct sshbuf *b, + struct sshkey *key) +{ + int ret = SSH_ERR_INTERNAL_ERROR; + BIGNUM *dsa_p = NULL, *dsa_q = NULL, *dsa_g = NULL, *dsa_pub_key = NULL; + + if (sshbuf_get_bignum2(b, &dsa_p) != 0 || + sshbuf_get_bignum2(b, &dsa_q) != 0 || + sshbuf_get_bignum2(b, &dsa_g) != 0 || + sshbuf_get_bignum2(b, &dsa_pub_key) != 0) { + ret = SSH_ERR_INVALID_FORMAT; + goto out; + } + if (!DSA_set0_pqg(key->dsa, dsa_p, dsa_q, dsa_g)) { + ret = SSH_ERR_LIBCRYPTO_ERROR; + goto out; + } + dsa_p = dsa_q = dsa_g = NULL; /* transferred */ + if (!DSA_set0_key(key->dsa, dsa_pub_key, NULL)) { + ret = SSH_ERR_LIBCRYPTO_ERROR; + goto out; + } + dsa_pub_key = NULL; /* transferred */ +#ifdef DEBUG_PK + DSA_print_fp(stderr, key->dsa, 8); +#endif + /* success */ + ret = 0; + out: + BN_clear_free(dsa_p); + BN_clear_free(dsa_q); + BN_clear_free(dsa_g); + BN_clear_free(dsa_pub_key); + return ret; +} + +static int +ssh_dss_deserialize_private(const char *ktype, struct sshbuf *b, + struct sshkey *key) +{ + int r; + BIGNUM *dsa_priv_key = NULL; + + if (!sshkey_is_cert(key)) { + if ((r = ssh_dss_deserialize_public(ktype, b, key)) != 0) + return r; + } + + if ((r = sshbuf_get_bignum2(b, &dsa_priv_key)) != 0) + return r; + if (!DSA_set0_key(key->dsa, NULL, dsa_priv_key)) { + BN_clear_free(dsa_priv_key); + return SSH_ERR_LIBCRYPTO_ERROR; + } + return 0; +} + +static int +ssh_dss_sign(struct sshkey *key, + u_char **sigp, size_t *lenp, + const u_char *data, size_t datalen, + const char *alg, const char *sk_provider, const char *sk_pin, u_int compat) +{ + DSA_SIG *sig = NULL; + const BIGNUM *sig_r, *sig_s; + u_char digest[SSH_DIGEST_MAX_LENGTH], sigblob[SIGBLOB_LEN]; + size_t rlen, slen, len, dlen = ssh_digest_bytes(SSH_DIGEST_SHA1); + struct sshbuf *b = NULL; + int ret = SSH_ERR_INVALID_ARGUMENT; + + if (lenp != NULL) + *lenp = 0; + if (sigp != NULL) + *sigp = NULL; + + if (key == NULL || key->dsa == NULL || + sshkey_type_plain(key->type) != KEY_DSA) + return SSH_ERR_INVALID_ARGUMENT; + if (dlen == 0) + return SSH_ERR_INTERNAL_ERROR; + + if ((ret = ssh_digest_memory(SSH_DIGEST_SHA1, data, datalen, + digest, sizeof(digest))) != 0) + goto out; + + if ((sig = DSA_do_sign(digest, dlen, key->dsa)) == NULL) { + ret = SSH_ERR_LIBCRYPTO_ERROR; + goto out; + } + + DSA_SIG_get0(sig, &sig_r, &sig_s); + rlen = BN_num_bytes(sig_r); + slen = BN_num_bytes(sig_s); + if (rlen > INTBLOB_LEN || slen > INTBLOB_LEN) { + ret = SSH_ERR_INTERNAL_ERROR; + goto out; + } + explicit_bzero(sigblob, SIGBLOB_LEN); + BN_bn2bin(sig_r, sigblob + SIGBLOB_LEN - INTBLOB_LEN - rlen); + BN_bn2bin(sig_s, sigblob + SIGBLOB_LEN - slen); + + if ((b = sshbuf_new()) == NULL) { + ret = SSH_ERR_ALLOC_FAIL; + goto out; + } + if ((ret = sshbuf_put_cstring(b, "ssh-dss")) != 0 || + (ret = sshbuf_put_string(b, sigblob, SIGBLOB_LEN)) != 0) + goto out; + + len = sshbuf_len(b); + if (sigp != NULL) { + if ((*sigp = malloc(len)) == NULL) { + ret = SSH_ERR_ALLOC_FAIL; + goto out; + } + memcpy(*sigp, sshbuf_ptr(b), len); + } + if (lenp != NULL) + *lenp = len; + ret = 0; + out: + explicit_bzero(digest, sizeof(digest)); + DSA_SIG_free(sig); + sshbuf_free(b); + return ret; +} + +static int +ssh_dss_verify(const struct sshkey *key, + const u_char *sig, size_t siglen, + const u_char *data, size_t dlen, const char *alg, u_int compat, + struct sshkey_sig_details **detailsp) +{ + DSA_SIG *dsig = NULL; + BIGNUM *sig_r = NULL, *sig_s = NULL; + u_char digest[SSH_DIGEST_MAX_LENGTH], *sigblob = NULL; + size_t len, hlen = ssh_digest_bytes(SSH_DIGEST_SHA1); + int ret = SSH_ERR_INTERNAL_ERROR; + struct sshbuf *b = NULL; + char *ktype = NULL; + + if (key == NULL || key->dsa == NULL || + sshkey_type_plain(key->type) != KEY_DSA || + sig == NULL || siglen == 0) + return SSH_ERR_INVALID_ARGUMENT; + if (hlen == 0) + return SSH_ERR_INTERNAL_ERROR; + + /* fetch signature */ + if ((b = sshbuf_from(sig, siglen)) == NULL) + return SSH_ERR_ALLOC_FAIL; + if (sshbuf_get_cstring(b, &ktype, NULL) != 0 || + sshbuf_get_string(b, &sigblob, &len) != 0) { + ret = SSH_ERR_INVALID_FORMAT; + goto out; + } + if (strcmp("ssh-dss", ktype) != 0) { + ret = SSH_ERR_KEY_TYPE_MISMATCH; + goto out; + } + if (sshbuf_len(b) != 0) { + ret = SSH_ERR_UNEXPECTED_TRAILING_DATA; + goto out; + } + + if (len != SIGBLOB_LEN) { + ret = SSH_ERR_INVALID_FORMAT; + goto out; + } + + /* parse signature */ + if ((dsig = DSA_SIG_new()) == NULL || + (sig_r = BN_new()) == NULL || + (sig_s = BN_new()) == NULL) { + ret = SSH_ERR_ALLOC_FAIL; + goto out; + } + if ((BN_bin2bn(sigblob, INTBLOB_LEN, sig_r) == NULL) || + (BN_bin2bn(sigblob + INTBLOB_LEN, INTBLOB_LEN, sig_s) == NULL)) { + ret = SSH_ERR_LIBCRYPTO_ERROR; + goto out; + } + if (!DSA_SIG_set0(dsig, sig_r, sig_s)) { + ret = SSH_ERR_LIBCRYPTO_ERROR; + goto out; + } + sig_r = sig_s = NULL; /* transferred */ + + /* sha1 the data */ + if ((ret = ssh_digest_memory(SSH_DIGEST_SHA1, data, dlen, + digest, sizeof(digest))) != 0) + goto out; + + switch (DSA_do_verify(digest, hlen, dsig, key->dsa)) { + case 1: + ret = 0; + break; + case 0: + ret = SSH_ERR_SIGNATURE_INVALID; + goto out; + default: + ret = SSH_ERR_LIBCRYPTO_ERROR; + goto out; + } + + out: + explicit_bzero(digest, sizeof(digest)); + DSA_SIG_free(dsig); + BN_clear_free(sig_r); + BN_clear_free(sig_s); + sshbuf_free(b); + free(ktype); + if (sigblob != NULL) + freezero(sigblob, len); + return ret; +} + +static const struct sshkey_impl_funcs sshkey_dss_funcs = { + /* .size = */ ssh_dss_size, + /* .alloc = */ ssh_dss_alloc, + /* .cleanup = */ ssh_dss_cleanup, + /* .equal = */ ssh_dss_equal, + /* .ssh_serialize_public = */ ssh_dss_serialize_public, + /* .ssh_deserialize_public = */ ssh_dss_deserialize_public, + /* .ssh_serialize_private = */ ssh_dss_serialize_private, + /* .ssh_deserialize_private = */ ssh_dss_deserialize_private, + /* .generate = */ ssh_dss_generate, + /* .copy_public = */ ssh_dss_copy_public, + /* .sign = */ ssh_dss_sign, + /* .verify = */ ssh_dss_verify, +}; + +const struct sshkey_impl sshkey_dss_impl = { + /* .name = */ "ssh-dss", + /* .shortname = */ "DSA", + /* .sigalg = */ NULL, + /* .type = */ KEY_DSA, + /* .nid = */ 0, + /* .cert = */ 0, + /* .sigonly = */ 0, + /* .keybits = */ 0, + /* .funcs = */ &sshkey_dss_funcs, +}; + +const struct sshkey_impl sshkey_dsa_cert_impl = { + /* .name = */ "ssh-dss-cert-v01@openssh.com", + /* .shortname = */ "DSA-CERT", + /* .sigalg = */ NULL, + /* .type = */ KEY_DSA_CERT, + /* .nid = */ 0, + /* .cert = */ 1, + /* .sigonly = */ 0, + /* .keybits = */ 0, + /* .funcs = */ &sshkey_dss_funcs, +}; +#endif /* WITH_OPENSSL */ |