djm@openbsd.org | 4ba0d54 | 2018-07-03 11:39:54 +0000 | [diff] [blame] | 1 | /* $OpenBSD: ssh-rsa.c,v 1.67 2018/07/03 11:39:54 djm Exp $ */ |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 2 | /* |
| 3 | * Copyright (c) 2000, 2003 Markus Friedl <markus@openbsd.org> |
| 4 | * |
| 5 | * Permission to use, copy, modify, and distribute this software for any |
| 6 | * purpose with or without fee is hereby granted, provided that the above |
| 7 | * copyright notice and this permission notice appear in all copies. |
| 8 | * |
| 9 | * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES |
| 10 | * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF |
| 11 | * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR |
| 12 | * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES |
| 13 | * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN |
| 14 | * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF |
| 15 | * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. |
| 16 | */ |
| 17 | |
| 18 | #include "includes.h" |
| 19 | |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 20 | #ifdef WITH_OPENSSL |
| 21 | |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 22 | #include <sys/types.h> |
| 23 | |
| 24 | #include <openssl/evp.h> |
| 25 | #include <openssl/err.h> |
| 26 | |
| 27 | #include <stdarg.h> |
| 28 | #include <string.h> |
| 29 | |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 30 | #include "sshbuf.h" |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 31 | #include "compat.h" |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 32 | #include "ssherr.h" |
| 33 | #define SSHKEY_INTERNAL |
| 34 | #include "sshkey.h" |
| 35 | #include "digest.h" |
djm@openbsd.org | 966ef47 | 2017-12-18 23:14:34 +0000 | [diff] [blame] | 36 | #include "log.h" |
Damien Miller | 0bc1bd8 | 2000-11-13 22:57:25 +1100 | [diff] [blame] | 37 | |
Damien Miller | 48f54b9 | 2018-09-13 12:13:50 +1000 | [diff] [blame] | 38 | #include "openbsd-compat/openssl-compat.h" |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 39 | |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 40 | static int openssh_RSA_verify(int, u_char *, size_t, u_char *, size_t, RSA *); |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 41 | |
markus@openbsd.org | 76c9fbb | 2015-12-04 16:41:28 +0000 | [diff] [blame] | 42 | static const char * |
| 43 | rsa_hash_alg_ident(int hash_alg) |
| 44 | { |
| 45 | switch (hash_alg) { |
| 46 | case SSH_DIGEST_SHA1: |
| 47 | return "ssh-rsa"; |
| 48 | case SSH_DIGEST_SHA256: |
| 49 | return "rsa-sha2-256"; |
| 50 | case SSH_DIGEST_SHA512: |
| 51 | return "rsa-sha2-512"; |
| 52 | } |
| 53 | return NULL; |
| 54 | } |
| 55 | |
djm@openbsd.org | 4ba0d54 | 2018-07-03 11:39:54 +0000 | [diff] [blame] | 56 | /* |
| 57 | * Returns the hash algorithm ID for a given algorithm identifier as used |
| 58 | * inside the signature blob, |
| 59 | */ |
markus@openbsd.org | 76c9fbb | 2015-12-04 16:41:28 +0000 | [diff] [blame] | 60 | static int |
djm@openbsd.org | 4ba0d54 | 2018-07-03 11:39:54 +0000 | [diff] [blame] | 61 | rsa_hash_id_from_ident(const char *ident) |
markus@openbsd.org | 76c9fbb | 2015-12-04 16:41:28 +0000 | [diff] [blame] | 62 | { |
djm@openbsd.org | 4ba0d54 | 2018-07-03 11:39:54 +0000 | [diff] [blame] | 63 | if (strcmp(ident, "ssh-rsa") == 0) |
markus@openbsd.org | 76c9fbb | 2015-12-04 16:41:28 +0000 | [diff] [blame] | 64 | return SSH_DIGEST_SHA1; |
| 65 | if (strcmp(ident, "rsa-sha2-256") == 0) |
| 66 | return SSH_DIGEST_SHA256; |
| 67 | if (strcmp(ident, "rsa-sha2-512") == 0) |
| 68 | return SSH_DIGEST_SHA512; |
markus@openbsd.org | 76c9fbb | 2015-12-04 16:41:28 +0000 | [diff] [blame] | 69 | return -1; |
| 70 | } |
| 71 | |
djm@openbsd.org | 4ba0d54 | 2018-07-03 11:39:54 +0000 | [diff] [blame] | 72 | /* |
| 73 | * Return the hash algorithm ID for the specified key name. This includes |
| 74 | * all the cases of rsa_hash_id_from_ident() but also the certificate key |
| 75 | * types. |
| 76 | */ |
| 77 | static int |
| 78 | rsa_hash_id_from_keyname(const char *alg) |
| 79 | { |
| 80 | int r; |
| 81 | |
| 82 | if ((r = rsa_hash_id_from_ident(alg)) != -1) |
| 83 | return r; |
| 84 | if (strcmp(alg, "ssh-rsa-cert-v01@openssh.com") == 0) |
| 85 | return SSH_DIGEST_SHA1; |
| 86 | if (strcmp(alg, "rsa-sha2-256-cert-v01@openssh.com") == 0) |
| 87 | return SSH_DIGEST_SHA256; |
| 88 | if (strcmp(alg, "rsa-sha2-512-cert-v01@openssh.com") == 0) |
| 89 | return SSH_DIGEST_SHA512; |
| 90 | return -1; |
| 91 | } |
| 92 | |
markus@openbsd.org | 76c9fbb | 2015-12-04 16:41:28 +0000 | [diff] [blame] | 93 | static int |
| 94 | rsa_hash_alg_nid(int type) |
| 95 | { |
| 96 | switch (type) { |
| 97 | case SSH_DIGEST_SHA1: |
| 98 | return NID_sha1; |
| 99 | case SSH_DIGEST_SHA256: |
| 100 | return NID_sha256; |
| 101 | case SSH_DIGEST_SHA512: |
| 102 | return NID_sha512; |
| 103 | default: |
| 104 | return -1; |
| 105 | } |
| 106 | } |
| 107 | |
djm@openbsd.org | 83fa3a0 | 2017-07-01 13:50:45 +0000 | [diff] [blame] | 108 | int |
djm@openbsd.org | 482d23b | 2018-09-13 02:08:33 +0000 | [diff] [blame] | 109 | ssh_rsa_complete_crt_parameters(struct sshkey *key, const BIGNUM *iqmp) |
djm@openbsd.org | 83fa3a0 | 2017-07-01 13:50:45 +0000 | [diff] [blame] | 110 | { |
djm@openbsd.org | 482d23b | 2018-09-13 02:08:33 +0000 | [diff] [blame] | 111 | const BIGNUM *rsa_p, *rsa_q, *rsa_d; |
| 112 | BIGNUM *aux = NULL, *d_consttime = NULL; |
| 113 | BIGNUM *rsa_dmq1 = NULL, *rsa_dmp1 = NULL, *rsa_iqmp = NULL; |
djm@openbsd.org | 83fa3a0 | 2017-07-01 13:50:45 +0000 | [diff] [blame] | 114 | BN_CTX *ctx = NULL; |
| 115 | int r; |
| 116 | |
| 117 | if (key == NULL || key->rsa == NULL || |
| 118 | sshkey_type_plain(key->type) != KEY_RSA) |
| 119 | return SSH_ERR_INVALID_ARGUMENT; |
| 120 | |
djm@openbsd.org | 482d23b | 2018-09-13 02:08:33 +0000 | [diff] [blame] | 121 | RSA_get0_key(key->rsa, NULL, NULL, &rsa_d); |
| 122 | RSA_get0_factors(key->rsa, &rsa_p, &rsa_q); |
| 123 | |
djm@openbsd.org | 83fa3a0 | 2017-07-01 13:50:45 +0000 | [diff] [blame] | 124 | if ((ctx = BN_CTX_new()) == NULL) |
| 125 | return SSH_ERR_ALLOC_FAIL; |
djm@openbsd.org | 482d23b | 2018-09-13 02:08:33 +0000 | [diff] [blame] | 126 | if ((aux = BN_new()) == NULL || |
| 127 | (rsa_dmq1 = BN_new()) == NULL || |
| 128 | (rsa_dmp1 = BN_new()) == NULL) |
| 129 | return SSH_ERR_ALLOC_FAIL; |
| 130 | if ((d_consttime = BN_dup(rsa_d)) == NULL || |
| 131 | (rsa_iqmp = BN_dup(iqmp)) == NULL) { |
djm@openbsd.org | 83fa3a0 | 2017-07-01 13:50:45 +0000 | [diff] [blame] | 132 | r = SSH_ERR_ALLOC_FAIL; |
| 133 | goto out; |
| 134 | } |
Alistair Delva | d9da10d | 2020-08-20 16:14:23 -0700 | [diff] [blame] | 135 | #if !defined(OPENSSL_IS_BORINGSSL) |
jsing@openbsd.org | d2b3db2 | 2018-02-14 16:27:24 +0000 | [diff] [blame] | 136 | BN_set_flags(aux, BN_FLG_CONSTTIME); |
djm@openbsd.org | 482d23b | 2018-09-13 02:08:33 +0000 | [diff] [blame] | 137 | BN_set_flags(d_consttime, BN_FLG_CONSTTIME); |
Alistair Delva | d9da10d | 2020-08-20 16:14:23 -0700 | [diff] [blame] | 138 | #endif |
djm@openbsd.org | 83fa3a0 | 2017-07-01 13:50:45 +0000 | [diff] [blame] | 139 | |
djm@openbsd.org | 482d23b | 2018-09-13 02:08:33 +0000 | [diff] [blame] | 140 | if ((BN_sub(aux, rsa_q, BN_value_one()) == 0) || |
| 141 | (BN_mod(rsa_dmq1, d_consttime, aux, ctx) == 0) || |
| 142 | (BN_sub(aux, rsa_p, BN_value_one()) == 0) || |
| 143 | (BN_mod(rsa_dmp1, d_consttime, aux, ctx) == 0)) { |
djm@openbsd.org | 83fa3a0 | 2017-07-01 13:50:45 +0000 | [diff] [blame] | 144 | r = SSH_ERR_LIBCRYPTO_ERROR; |
| 145 | goto out; |
| 146 | } |
djm@openbsd.org | 482d23b | 2018-09-13 02:08:33 +0000 | [diff] [blame] | 147 | if (!RSA_set0_crt_params(key->rsa, rsa_dmp1, rsa_dmq1, rsa_iqmp)) { |
| 148 | r = SSH_ERR_LIBCRYPTO_ERROR; |
| 149 | goto out; |
| 150 | } |
| 151 | rsa_dmp1 = rsa_dmq1 = rsa_iqmp = NULL; /* transferred */ |
| 152 | /* success */ |
djm@openbsd.org | 83fa3a0 | 2017-07-01 13:50:45 +0000 | [diff] [blame] | 153 | r = 0; |
| 154 | out: |
| 155 | BN_clear_free(aux); |
djm@openbsd.org | 482d23b | 2018-09-13 02:08:33 +0000 | [diff] [blame] | 156 | BN_clear_free(d_consttime); |
| 157 | BN_clear_free(rsa_dmp1); |
| 158 | BN_clear_free(rsa_dmq1); |
| 159 | BN_clear_free(rsa_iqmp); |
djm@openbsd.org | 83fa3a0 | 2017-07-01 13:50:45 +0000 | [diff] [blame] | 160 | BN_CTX_free(ctx); |
| 161 | return r; |
| 162 | } |
| 163 | |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 164 | /* RSASSA-PKCS1-v1_5 (PKCS #1 v2.0 signature) with SHA1 */ |
| 165 | int |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 166 | ssh_rsa_sign(const struct sshkey *key, u_char **sigp, size_t *lenp, |
markus@openbsd.org | 76c9fbb | 2015-12-04 16:41:28 +0000 | [diff] [blame] | 167 | const u_char *data, size_t datalen, const char *alg_ident) |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 168 | { |
djm@openbsd.org | 482d23b | 2018-09-13 02:08:33 +0000 | [diff] [blame] | 169 | const BIGNUM *rsa_n; |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 170 | u_char digest[SSH_DIGEST_MAX_LENGTH], *sig = NULL; |
jsing@openbsd.org | 1749991 | 2018-02-07 05:17:56 +0000 | [diff] [blame] | 171 | size_t slen = 0; |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 172 | u_int dlen, len; |
markus@openbsd.org | 76c9fbb | 2015-12-04 16:41:28 +0000 | [diff] [blame] | 173 | int nid, hash_alg, ret = SSH_ERR_INTERNAL_ERROR; |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 174 | struct sshbuf *b = NULL; |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 175 | |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 176 | if (lenp != NULL) |
| 177 | *lenp = 0; |
| 178 | if (sigp != NULL) |
| 179 | *sigp = NULL; |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 180 | |
djm@openbsd.org | 445e218 | 2016-09-12 23:39:34 +0000 | [diff] [blame] | 181 | if (alg_ident == NULL || strlen(alg_ident) == 0) |
markus@openbsd.org | 6262a05 | 2015-12-07 20:04:09 +0000 | [diff] [blame] | 182 | hash_alg = SSH_DIGEST_SHA1; |
| 183 | else |
djm@openbsd.org | 4ba0d54 | 2018-07-03 11:39:54 +0000 | [diff] [blame] | 184 | hash_alg = rsa_hash_id_from_keyname(alg_ident); |
markus@openbsd.org | 76c9fbb | 2015-12-04 16:41:28 +0000 | [diff] [blame] | 185 | if (key == NULL || key->rsa == NULL || hash_alg == -1 || |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 186 | sshkey_type_plain(key->type) != KEY_RSA) |
| 187 | return SSH_ERR_INVALID_ARGUMENT; |
djm@openbsd.org | 482d23b | 2018-09-13 02:08:33 +0000 | [diff] [blame] | 188 | RSA_get0_key(key->rsa, &rsa_n, NULL, NULL); |
| 189 | if (BN_num_bits(rsa_n) < SSH_RSA_MINIMUM_MODULUS_SIZE) |
djm@openbsd.org | bd636f4 | 2017-05-07 23:15:59 +0000 | [diff] [blame] | 190 | return SSH_ERR_KEY_LENGTH; |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 191 | slen = RSA_size(key->rsa); |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 192 | if (slen <= 0 || slen > SSHBUF_MAX_BIGNUM) |
| 193 | return SSH_ERR_INVALID_ARGUMENT; |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 194 | |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 195 | /* hash the data */ |
markus@openbsd.org | 76c9fbb | 2015-12-04 16:41:28 +0000 | [diff] [blame] | 196 | nid = rsa_hash_alg_nid(hash_alg); |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 197 | if ((dlen = ssh_digest_bytes(hash_alg)) == 0) |
| 198 | return SSH_ERR_INTERNAL_ERROR; |
| 199 | if ((ret = ssh_digest_memory(hash_alg, data, datalen, |
| 200 | digest, sizeof(digest))) != 0) |
| 201 | goto out; |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 202 | |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 203 | if ((sig = malloc(slen)) == NULL) { |
| 204 | ret = SSH_ERR_ALLOC_FAIL; |
| 205 | goto out; |
| 206 | } |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 207 | |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 208 | if (RSA_sign(nid, digest, dlen, sig, &len, key->rsa) != 1) { |
| 209 | ret = SSH_ERR_LIBCRYPTO_ERROR; |
| 210 | goto out; |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 211 | } |
| 212 | if (len < slen) { |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 213 | size_t diff = slen - len; |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 214 | memmove(sig + diff, sig, len); |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 215 | explicit_bzero(sig, diff); |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 216 | } else if (len > slen) { |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 217 | ret = SSH_ERR_INTERNAL_ERROR; |
| 218 | goto out; |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 219 | } |
| 220 | /* encode signature */ |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 221 | if ((b = sshbuf_new()) == NULL) { |
| 222 | ret = SSH_ERR_ALLOC_FAIL; |
| 223 | goto out; |
| 224 | } |
markus@openbsd.org | 76c9fbb | 2015-12-04 16:41:28 +0000 | [diff] [blame] | 225 | if ((ret = sshbuf_put_cstring(b, rsa_hash_alg_ident(hash_alg))) != 0 || |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 226 | (ret = sshbuf_put_string(b, sig, slen)) != 0) |
| 227 | goto out; |
| 228 | len = sshbuf_len(b); |
| 229 | if (sigp != NULL) { |
| 230 | if ((*sigp = malloc(len)) == NULL) { |
| 231 | ret = SSH_ERR_ALLOC_FAIL; |
| 232 | goto out; |
| 233 | } |
| 234 | memcpy(*sigp, sshbuf_ptr(b), len); |
| 235 | } |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 236 | if (lenp != NULL) |
| 237 | *lenp = len; |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 238 | ret = 0; |
| 239 | out: |
| 240 | explicit_bzero(digest, sizeof(digest)); |
jsing@openbsd.org | 1749991 | 2018-02-07 05:17:56 +0000 | [diff] [blame] | 241 | freezero(sig, slen); |
mmcc@openbsd.org | 52d7078 | 2015-12-11 04:21:11 +0000 | [diff] [blame] | 242 | sshbuf_free(b); |
djm@openbsd.org | 4ef702e | 2015-06-15 01:32:50 +0000 | [diff] [blame] | 243 | return ret; |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 244 | } |
| 245 | |
| 246 | int |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 247 | ssh_rsa_verify(const struct sshkey *key, |
djm@openbsd.org | 04c7e28 | 2017-12-18 02:25:15 +0000 | [diff] [blame] | 248 | const u_char *sig, size_t siglen, const u_char *data, size_t datalen, |
| 249 | const char *alg) |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 250 | { |
djm@openbsd.org | 482d23b | 2018-09-13 02:08:33 +0000 | [diff] [blame] | 251 | const BIGNUM *rsa_n; |
djm@openbsd.org | 04c7e28 | 2017-12-18 02:25:15 +0000 | [diff] [blame] | 252 | char *sigtype = NULL; |
djm@openbsd.org | 4ba0d54 | 2018-07-03 11:39:54 +0000 | [diff] [blame] | 253 | int hash_alg, want_alg, ret = SSH_ERR_INTERNAL_ERROR; |
jsing@openbsd.org | 1749991 | 2018-02-07 05:17:56 +0000 | [diff] [blame] | 254 | size_t len = 0, diff, modlen, dlen; |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 255 | struct sshbuf *b = NULL; |
| 256 | u_char digest[SSH_DIGEST_MAX_LENGTH], *osigblob, *sigblob = NULL; |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 257 | |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 258 | if (key == NULL || key->rsa == NULL || |
| 259 | sshkey_type_plain(key->type) != KEY_RSA || |
djm@openbsd.org | b6e0140 | 2016-04-21 06:08:02 +0000 | [diff] [blame] | 260 | sig == NULL || siglen == 0) |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 261 | return SSH_ERR_INVALID_ARGUMENT; |
djm@openbsd.org | 482d23b | 2018-09-13 02:08:33 +0000 | [diff] [blame] | 262 | RSA_get0_key(key->rsa, &rsa_n, NULL, NULL); |
| 263 | if (BN_num_bits(rsa_n) < SSH_RSA_MINIMUM_MODULUS_SIZE) |
djm@openbsd.org | bd636f4 | 2017-05-07 23:15:59 +0000 | [diff] [blame] | 264 | return SSH_ERR_KEY_LENGTH; |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 265 | |
markus@openbsd.org | 76c9fbb | 2015-12-04 16:41:28 +0000 | [diff] [blame] | 266 | if ((b = sshbuf_from(sig, siglen)) == NULL) |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 267 | return SSH_ERR_ALLOC_FAIL; |
djm@openbsd.org | 04c7e28 | 2017-12-18 02:25:15 +0000 | [diff] [blame] | 268 | if (sshbuf_get_cstring(b, &sigtype, NULL) != 0) { |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 269 | ret = SSH_ERR_INVALID_FORMAT; |
| 270 | goto out; |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 271 | } |
djm@openbsd.org | 4ba0d54 | 2018-07-03 11:39:54 +0000 | [diff] [blame] | 272 | if ((hash_alg = rsa_hash_id_from_ident(sigtype)) == -1) { |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 273 | ret = SSH_ERR_KEY_TYPE_MISMATCH; |
| 274 | goto out; |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 275 | } |
djm@openbsd.org | 4ba0d54 | 2018-07-03 11:39:54 +0000 | [diff] [blame] | 276 | /* |
| 277 | * Allow ssh-rsa-cert-v01 certs to generate SHA2 signatures for |
| 278 | * legacy reasons, but otherwise the signature type should match. |
| 279 | */ |
| 280 | if (alg != NULL && strcmp(alg, "ssh-rsa-cert-v01@openssh.com") != 0) { |
| 281 | if ((want_alg = rsa_hash_id_from_keyname(alg)) == -1) { |
| 282 | ret = SSH_ERR_INVALID_ARGUMENT; |
| 283 | goto out; |
| 284 | } |
| 285 | if (hash_alg != want_alg) { |
| 286 | ret = SSH_ERR_SIGNATURE_INVALID; |
| 287 | goto out; |
| 288 | } |
| 289 | } |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 290 | if (sshbuf_get_string(b, &sigblob, &len) != 0) { |
| 291 | ret = SSH_ERR_INVALID_FORMAT; |
| 292 | goto out; |
| 293 | } |
| 294 | if (sshbuf_len(b) != 0) { |
| 295 | ret = SSH_ERR_UNEXPECTED_TRAILING_DATA; |
| 296 | goto out; |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 297 | } |
| 298 | /* RSA_verify expects a signature of RSA_size */ |
| 299 | modlen = RSA_size(key->rsa); |
| 300 | if (len > modlen) { |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 301 | ret = SSH_ERR_KEY_BITS_MISMATCH; |
| 302 | goto out; |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 303 | } else if (len < modlen) { |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 304 | diff = modlen - len; |
| 305 | osigblob = sigblob; |
| 306 | if ((sigblob = realloc(sigblob, modlen)) == NULL) { |
| 307 | sigblob = osigblob; /* put it back for clear/free */ |
| 308 | ret = SSH_ERR_ALLOC_FAIL; |
| 309 | goto out; |
| 310 | } |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 311 | memmove(sigblob + diff, sigblob, len); |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 312 | explicit_bzero(sigblob, diff); |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 313 | len = modlen; |
| 314 | } |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 315 | if ((dlen = ssh_digest_bytes(hash_alg)) == 0) { |
| 316 | ret = SSH_ERR_INTERNAL_ERROR; |
| 317 | goto out; |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 318 | } |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 319 | if ((ret = ssh_digest_memory(hash_alg, data, datalen, |
| 320 | digest, sizeof(digest))) != 0) |
| 321 | goto out; |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 322 | |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 323 | ret = openssh_RSA_verify(hash_alg, digest, dlen, sigblob, len, |
| 324 | key->rsa); |
| 325 | out: |
jsing@openbsd.org | 1749991 | 2018-02-07 05:17:56 +0000 | [diff] [blame] | 326 | freezero(sigblob, len); |
djm@openbsd.org | 04c7e28 | 2017-12-18 02:25:15 +0000 | [diff] [blame] | 327 | free(sigtype); |
mmcc@openbsd.org | 52d7078 | 2015-12-11 04:21:11 +0000 | [diff] [blame] | 328 | sshbuf_free(b); |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 329 | explicit_bzero(digest, sizeof(digest)); |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 330 | return ret; |
| 331 | } |
| 332 | |
| 333 | /* |
| 334 | * See: |
| 335 | * http://www.rsasecurity.com/rsalabs/pkcs/pkcs-1/ |
| 336 | * ftp://ftp.rsasecurity.com/pub/pkcs/pkcs-1/pkcs-1v2-1.asn |
| 337 | */ |
markus@openbsd.org | 76c9fbb | 2015-12-04 16:41:28 +0000 | [diff] [blame] | 338 | |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 339 | /* |
| 340 | * id-sha1 OBJECT IDENTIFIER ::= { iso(1) identified-organization(3) |
| 341 | * oiw(14) secsig(3) algorithms(2) 26 } |
| 342 | */ |
| 343 | static const u_char id_sha1[] = { |
| 344 | 0x30, 0x21, /* type Sequence, length 0x21 (33) */ |
| 345 | 0x30, 0x09, /* type Sequence, length 0x09 */ |
| 346 | 0x06, 0x05, /* type OID, length 0x05 */ |
| 347 | 0x2b, 0x0e, 0x03, 0x02, 0x1a, /* id-sha1 OID */ |
| 348 | 0x05, 0x00, /* NULL */ |
| 349 | 0x04, 0x14 /* Octet string, length 0x14 (20), followed by sha1 hash */ |
| 350 | }; |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 351 | |
markus@openbsd.org | 76c9fbb | 2015-12-04 16:41:28 +0000 | [diff] [blame] | 352 | /* |
| 353 | * See http://csrc.nist.gov/groups/ST/crypto_apps_infra/csor/algorithms.html |
| 354 | * id-sha256 OBJECT IDENTIFIER ::= { joint-iso-itu-t(2) country(16) us(840) |
| 355 | * organization(1) gov(101) csor(3) nistAlgorithm(4) hashAlgs(2) |
| 356 | * id-sha256(1) } |
| 357 | */ |
| 358 | static const u_char id_sha256[] = { |
| 359 | 0x30, 0x31, /* type Sequence, length 0x31 (49) */ |
| 360 | 0x30, 0x0d, /* type Sequence, length 0x0d (13) */ |
| 361 | 0x06, 0x09, /* type OID, length 0x09 */ |
| 362 | 0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x01, /* id-sha256 */ |
| 363 | 0x05, 0x00, /* NULL */ |
| 364 | 0x04, 0x20 /* Octet string, length 0x20 (32), followed by sha256 hash */ |
| 365 | }; |
| 366 | |
| 367 | /* |
| 368 | * See http://csrc.nist.gov/groups/ST/crypto_apps_infra/csor/algorithms.html |
| 369 | * id-sha512 OBJECT IDENTIFIER ::= { joint-iso-itu-t(2) country(16) us(840) |
| 370 | * organization(1) gov(101) csor(3) nistAlgorithm(4) hashAlgs(2) |
| 371 | * id-sha256(3) } |
| 372 | */ |
| 373 | static const u_char id_sha512[] = { |
| 374 | 0x30, 0x51, /* type Sequence, length 0x51 (81) */ |
| 375 | 0x30, 0x0d, /* type Sequence, length 0x0d (13) */ |
| 376 | 0x06, 0x09, /* type OID, length 0x09 */ |
| 377 | 0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x03, /* id-sha512 */ |
| 378 | 0x05, 0x00, /* NULL */ |
| 379 | 0x04, 0x40 /* Octet string, length 0x40 (64), followed by sha512 hash */ |
| 380 | }; |
| 381 | |
| 382 | static int |
| 383 | rsa_hash_alg_oid(int hash_alg, const u_char **oidp, size_t *oidlenp) |
| 384 | { |
| 385 | switch (hash_alg) { |
| 386 | case SSH_DIGEST_SHA1: |
| 387 | *oidp = id_sha1; |
| 388 | *oidlenp = sizeof(id_sha1); |
| 389 | break; |
| 390 | case SSH_DIGEST_SHA256: |
| 391 | *oidp = id_sha256; |
| 392 | *oidlenp = sizeof(id_sha256); |
| 393 | break; |
| 394 | case SSH_DIGEST_SHA512: |
| 395 | *oidp = id_sha512; |
| 396 | *oidlenp = sizeof(id_sha512); |
| 397 | break; |
| 398 | default: |
| 399 | return SSH_ERR_INVALID_ARGUMENT; |
| 400 | } |
| 401 | return 0; |
| 402 | } |
| 403 | |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 404 | static int |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 405 | openssh_RSA_verify(int hash_alg, u_char *hash, size_t hashlen, |
| 406 | u_char *sigbuf, size_t siglen, RSA *rsa) |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 407 | { |
djm@openbsd.org | 61942ea | 2015-09-09 00:52:44 +0000 | [diff] [blame] | 408 | size_t rsasize = 0, oidlen = 0, hlen = 0; |
| 409 | int ret, len, oidmatch, hashmatch; |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 410 | const u_char *oid = NULL; |
| 411 | u_char *decrypted = NULL; |
| 412 | |
markus@openbsd.org | 76c9fbb | 2015-12-04 16:41:28 +0000 | [diff] [blame] | 413 | if ((ret = rsa_hash_alg_oid(hash_alg, &oid, &oidlen)) != 0) |
| 414 | return ret; |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 415 | ret = SSH_ERR_INTERNAL_ERROR; |
markus@openbsd.org | 76c9fbb | 2015-12-04 16:41:28 +0000 | [diff] [blame] | 416 | hlen = ssh_digest_bytes(hash_alg); |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 417 | if (hashlen != hlen) { |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 418 | ret = SSH_ERR_INVALID_ARGUMENT; |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 419 | goto done; |
| 420 | } |
| 421 | rsasize = RSA_size(rsa); |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 422 | if (rsasize <= 0 || rsasize > SSHBUF_MAX_BIGNUM || |
| 423 | siglen == 0 || siglen > rsasize) { |
| 424 | ret = SSH_ERR_INVALID_ARGUMENT; |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 425 | goto done; |
| 426 | } |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 427 | if ((decrypted = malloc(rsasize)) == NULL) { |
| 428 | ret = SSH_ERR_ALLOC_FAIL; |
| 429 | goto done; |
| 430 | } |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 431 | if ((len = RSA_public_decrypt(siglen, sigbuf, decrypted, rsa, |
| 432 | RSA_PKCS1_PADDING)) < 0) { |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 433 | ret = SSH_ERR_LIBCRYPTO_ERROR; |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 434 | goto done; |
| 435 | } |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 436 | if (len < 0 || (size_t)len != hlen + oidlen) { |
| 437 | ret = SSH_ERR_INVALID_FORMAT; |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 438 | goto done; |
| 439 | } |
| 440 | oidmatch = timingsafe_bcmp(decrypted, oid, oidlen) == 0; |
| 441 | hashmatch = timingsafe_bcmp(decrypted + oidlen, hash, hlen) == 0; |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 442 | if (!oidmatch || !hashmatch) { |
| 443 | ret = SSH_ERR_SIGNATURE_INVALID; |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 444 | goto done; |
| 445 | } |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 446 | ret = 0; |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 447 | done: |
jsing@openbsd.org | 1749991 | 2018-02-07 05:17:56 +0000 | [diff] [blame] | 448 | freezero(decrypted, rsasize); |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 449 | return ret; |
| 450 | } |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 451 | #endif /* WITH_OPENSSL */ |