Damien Miller | 8668706 | 2014-07-02 15:28:02 +1000 | [diff] [blame] | 1 | /* $OpenBSD: ssh-rsa.c,v 1.52 2014/06/24 01:13:21 djm Exp $ */ |
Damien Miller | 0bc1bd8 | 2000-11-13 22:57:25 +1100 | [diff] [blame] | 2 | /* |
Darren Tucker | a251f80 | 2003-06-22 20:45:15 +1000 | [diff] [blame] | 3 | * Copyright (c) 2000, 2003 Markus Friedl <markus@openbsd.org> |
Damien Miller | 0bc1bd8 | 2000-11-13 22:57:25 +1100 | [diff] [blame] | 4 | * |
Darren Tucker | a251f80 | 2003-06-22 20:45:15 +1000 | [diff] [blame] | 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. |
Damien Miller | 0bc1bd8 | 2000-11-13 22:57:25 +1100 | [diff] [blame] | 8 | * |
Darren Tucker | a251f80 | 2003-06-22 20:45:15 +1000 | [diff] [blame] | 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. |
Damien Miller | 0bc1bd8 | 2000-11-13 22:57:25 +1100 | [diff] [blame] | 16 | */ |
Damien Miller | d783435 | 2006-08-05 12:39:39 +1000 | [diff] [blame] | 17 | |
Damien Miller | 0bc1bd8 | 2000-11-13 22:57:25 +1100 | [diff] [blame] | 18 | #include "includes.h" |
Damien Miller | 0bc1bd8 | 2000-11-13 22:57:25 +1100 | [diff] [blame] | 19 | |
Damien Miller | d783435 | 2006-08-05 12:39:39 +1000 | [diff] [blame] | 20 | #include <sys/types.h> |
| 21 | |
Damien Miller | 0bc1bd8 | 2000-11-13 22:57:25 +1100 | [diff] [blame] | 22 | #include <openssl/evp.h> |
Damien Miller | 0bc1bd8 | 2000-11-13 22:57:25 +1100 | [diff] [blame] | 23 | #include <openssl/err.h> |
| 24 | |
Damien Miller | ded319c | 2006-09-01 15:38:36 +1000 | [diff] [blame] | 25 | #include <stdarg.h> |
Damien Miller | e3476ed | 2006-07-24 14:13:33 +1000 | [diff] [blame] | 26 | #include <string.h> |
| 27 | |
Damien Miller | 8668706 | 2014-07-02 15:28:02 +1000 | [diff] [blame] | 28 | #include "sshbuf.h" |
Ben Lindstrom | 60a4381 | 2001-03-29 00:32:56 +0000 | [diff] [blame] | 29 | #include "compat.h" |
Damien Miller | 8668706 | 2014-07-02 15:28:02 +1000 | [diff] [blame] | 30 | #include "ssherr.h" |
| 31 | #define SSHKEY_INTERNAL |
| 32 | #include "sshkey.h" |
Damien Miller | b3051d0 | 2014-01-10 10:58:53 +1100 | [diff] [blame] | 33 | #include "digest.h" |
Damien Miller | 0bc1bd8 | 2000-11-13 22:57:25 +1100 | [diff] [blame] | 34 | |
Damien Miller | 8668706 | 2014-07-02 15:28:02 +1000 | [diff] [blame] | 35 | static int openssh_RSA_verify(int, u_char *, size_t, u_char *, size_t, RSA *); |
Ben Lindstrom | 0deb5d9 | 2002-08-20 18:40:03 +0000 | [diff] [blame] | 36 | |
Damien Miller | 0bc1bd8 | 2000-11-13 22:57:25 +1100 | [diff] [blame] | 37 | /* RSASSA-PKCS1-v1_5 (PKCS #1 v2.0 signature) with SHA1 */ |
| 38 | int |
Damien Miller | 8668706 | 2014-07-02 15:28:02 +1000 | [diff] [blame] | 39 | ssh_rsa_sign(const struct sshkey *key, u_char **sigp, size_t *lenp, |
| 40 | const u_char *data, size_t datalen, u_int compat) |
Damien Miller | 0bc1bd8 | 2000-11-13 22:57:25 +1100 | [diff] [blame] | 41 | { |
Damien Miller | b3051d0 | 2014-01-10 10:58:53 +1100 | [diff] [blame] | 42 | int hash_alg; |
Damien Miller | 8668706 | 2014-07-02 15:28:02 +1000 | [diff] [blame] | 43 | u_char digest[SSH_DIGEST_MAX_LENGTH], *sig = NULL; |
| 44 | size_t slen; |
| 45 | u_int dlen, len; |
| 46 | int nid, ret = SSH_ERR_INTERNAL_ERROR; |
| 47 | struct sshbuf *b = NULL; |
Damien Miller | 0bc1bd8 | 2000-11-13 22:57:25 +1100 | [diff] [blame] | 48 | |
Damien Miller | 8668706 | 2014-07-02 15:28:02 +1000 | [diff] [blame] | 49 | if (lenp != NULL) |
| 50 | *lenp = 0; |
| 51 | if (sigp != NULL) |
| 52 | *sigp = NULL; |
| 53 | |
| 54 | if (key == NULL || key->rsa == NULL || |
| 55 | sshkey_type_plain(key->type) != KEY_RSA) |
| 56 | return SSH_ERR_INVALID_ARGUMENT; |
| 57 | slen = RSA_size(key->rsa); |
| 58 | if (slen <= 0 || slen > SSHBUF_MAX_BIGNUM) |
| 59 | return SSH_ERR_INVALID_ARGUMENT; |
Damien Miller | 3e19295 | 2013-12-29 17:47:50 +1100 | [diff] [blame] | 60 | |
Damien Miller | b3051d0 | 2014-01-10 10:58:53 +1100 | [diff] [blame] | 61 | /* hash the data */ |
| 62 | hash_alg = SSH_DIGEST_SHA1; |
Damien Miller | 324541e | 2013-12-31 12:25:40 +1100 | [diff] [blame] | 63 | nid = NID_sha1; |
Damien Miller | 8668706 | 2014-07-02 15:28:02 +1000 | [diff] [blame] | 64 | if ((dlen = ssh_digest_bytes(hash_alg)) == 0) |
| 65 | return SSH_ERR_INTERNAL_ERROR; |
| 66 | if ((ret = ssh_digest_memory(hash_alg, data, datalen, |
| 67 | digest, sizeof(digest))) != 0) |
| 68 | goto out; |
| 69 | |
| 70 | if ((sig = malloc(slen)) == NULL) { |
| 71 | ret = SSH_ERR_ALLOC_FAIL; |
| 72 | goto out; |
Damien Miller | b3051d0 | 2014-01-10 10:58:53 +1100 | [diff] [blame] | 73 | } |
Damien Miller | 0bc1bd8 | 2000-11-13 22:57:25 +1100 | [diff] [blame] | 74 | |
Damien Miller | 8668706 | 2014-07-02 15:28:02 +1000 | [diff] [blame] | 75 | if (RSA_sign(nid, digest, dlen, sig, &len, key->rsa) != 1) { |
| 76 | ret = SSH_ERR_LIBCRYPTO_ERROR; |
| 77 | goto out; |
Damien Miller | 0bc1bd8 | 2000-11-13 22:57:25 +1100 | [diff] [blame] | 78 | } |
| 79 | if (len < slen) { |
Damien Miller | 8668706 | 2014-07-02 15:28:02 +1000 | [diff] [blame] | 80 | size_t diff = slen - len; |
Damien Miller | 0bc1bd8 | 2000-11-13 22:57:25 +1100 | [diff] [blame] | 81 | memmove(sig + diff, sig, len); |
Damien Miller | a5103f4 | 2014-02-04 11:20:14 +1100 | [diff] [blame] | 82 | explicit_bzero(sig, diff); |
Damien Miller | 0bc1bd8 | 2000-11-13 22:57:25 +1100 | [diff] [blame] | 83 | } else if (len > slen) { |
Damien Miller | 8668706 | 2014-07-02 15:28:02 +1000 | [diff] [blame] | 84 | ret = SSH_ERR_INTERNAL_ERROR; |
| 85 | goto out; |
Damien Miller | 0bc1bd8 | 2000-11-13 22:57:25 +1100 | [diff] [blame] | 86 | } |
| 87 | /* encode signature */ |
Damien Miller | 8668706 | 2014-07-02 15:28:02 +1000 | [diff] [blame] | 88 | if ((b = sshbuf_new()) == NULL) { |
| 89 | ret = SSH_ERR_ALLOC_FAIL; |
| 90 | goto out; |
| 91 | } |
| 92 | if ((ret = sshbuf_put_cstring(b, "ssh-rsa")) != 0 || |
| 93 | (ret = sshbuf_put_string(b, sig, slen)) != 0) |
| 94 | goto out; |
| 95 | len = sshbuf_len(b); |
| 96 | if (sigp != NULL) { |
| 97 | if ((*sigp = malloc(len)) == NULL) { |
| 98 | ret = SSH_ERR_ALLOC_FAIL; |
| 99 | goto out; |
| 100 | } |
| 101 | memcpy(*sigp, sshbuf_ptr(b), len); |
| 102 | } |
Ben Lindstrom | 2bf759c | 2002-07-07 22:13:31 +0000 | [diff] [blame] | 103 | if (lenp != NULL) |
| 104 | *lenp = len; |
Damien Miller | 8668706 | 2014-07-02 15:28:02 +1000 | [diff] [blame] | 105 | ret = 0; |
| 106 | out: |
| 107 | explicit_bzero(digest, sizeof(digest)); |
| 108 | if (sig != NULL) { |
| 109 | explicit_bzero(sig, slen); |
| 110 | free(sig); |
Ben Lindstrom | 2bf759c | 2002-07-07 22:13:31 +0000 | [diff] [blame] | 111 | } |
Damien Miller | 8668706 | 2014-07-02 15:28:02 +1000 | [diff] [blame] | 112 | if (b != NULL) |
| 113 | sshbuf_free(b); |
Damien Miller | 0bc1bd8 | 2000-11-13 22:57:25 +1100 | [diff] [blame] | 114 | return 0; |
| 115 | } |
| 116 | |
| 117 | int |
Damien Miller | 8668706 | 2014-07-02 15:28:02 +1000 | [diff] [blame] | 118 | ssh_rsa_verify(const struct sshkey *key, |
| 119 | const u_char *signature, size_t signaturelen, |
| 120 | const u_char *data, size_t datalen, u_int compat) |
Damien Miller | 0bc1bd8 | 2000-11-13 22:57:25 +1100 | [diff] [blame] | 121 | { |
Damien Miller | 8668706 | 2014-07-02 15:28:02 +1000 | [diff] [blame] | 122 | char *ktype = NULL; |
| 123 | int hash_alg, ret = SSH_ERR_INTERNAL_ERROR; |
| 124 | size_t len, diff, modlen, dlen; |
| 125 | struct sshbuf *b = NULL; |
| 126 | u_char digest[SSH_DIGEST_MAX_LENGTH], *osigblob, *sigblob = NULL; |
Damien Miller | 0bc1bd8 | 2000-11-13 22:57:25 +1100 | [diff] [blame] | 127 | |
Damien Miller | 8668706 | 2014-07-02 15:28:02 +1000 | [diff] [blame] | 128 | if (key == NULL || key->rsa == NULL || |
| 129 | sshkey_type_plain(key->type) != KEY_RSA || |
| 130 | BN_num_bits(key->rsa->n) < SSH_RSA_MINIMUM_MODULUS_SIZE) |
| 131 | return SSH_ERR_INVALID_ARGUMENT; |
Damien Miller | 3e19295 | 2013-12-29 17:47:50 +1100 | [diff] [blame] | 132 | |
Damien Miller | 8668706 | 2014-07-02 15:28:02 +1000 | [diff] [blame] | 133 | if ((b = sshbuf_from(signature, signaturelen)) == NULL) |
| 134 | return SSH_ERR_ALLOC_FAIL; |
| 135 | if (sshbuf_get_cstring(b, &ktype, NULL) != 0) { |
| 136 | ret = SSH_ERR_INVALID_FORMAT; |
| 137 | goto out; |
Ben Lindstrom | bf555ba | 2001-01-18 02:04:35 +0000 | [diff] [blame] | 138 | } |
Damien Miller | 0bc1bd8 | 2000-11-13 22:57:25 +1100 | [diff] [blame] | 139 | if (strcmp("ssh-rsa", ktype) != 0) { |
Damien Miller | 8668706 | 2014-07-02 15:28:02 +1000 | [diff] [blame] | 140 | ret = SSH_ERR_KEY_TYPE_MISMATCH; |
| 141 | goto out; |
Damien Miller | 0bc1bd8 | 2000-11-13 22:57:25 +1100 | [diff] [blame] | 142 | } |
Damien Miller | 8668706 | 2014-07-02 15:28:02 +1000 | [diff] [blame] | 143 | if (sshbuf_get_string(b, &sigblob, &len) != 0) { |
| 144 | ret = SSH_ERR_INVALID_FORMAT; |
| 145 | goto out; |
| 146 | } |
| 147 | if (sshbuf_len(b) != 0) { |
| 148 | ret = SSH_ERR_UNEXPECTED_TRAILING_DATA; |
| 149 | goto out; |
Damien Miller | 0bc1bd8 | 2000-11-13 22:57:25 +1100 | [diff] [blame] | 150 | } |
Ben Lindstrom | ceae9d1 | 2002-06-06 20:55:04 +0000 | [diff] [blame] | 151 | /* RSA_verify expects a signature of RSA_size */ |
| 152 | modlen = RSA_size(key->rsa); |
| 153 | if (len > modlen) { |
Damien Miller | 8668706 | 2014-07-02 15:28:02 +1000 | [diff] [blame] | 154 | ret = SSH_ERR_KEY_BITS_MISMATCH; |
| 155 | goto out; |
Ben Lindstrom | ceae9d1 | 2002-06-06 20:55:04 +0000 | [diff] [blame] | 156 | } else if (len < modlen) { |
Damien Miller | 8668706 | 2014-07-02 15:28:02 +1000 | [diff] [blame] | 157 | diff = modlen - len; |
| 158 | osigblob = sigblob; |
| 159 | if ((sigblob = realloc(sigblob, modlen)) == NULL) { |
| 160 | sigblob = osigblob; /* put it back for clear/free */ |
| 161 | ret = SSH_ERR_ALLOC_FAIL; |
| 162 | goto out; |
| 163 | } |
Ben Lindstrom | ceae9d1 | 2002-06-06 20:55:04 +0000 | [diff] [blame] | 164 | memmove(sigblob + diff, sigblob, len); |
Damien Miller | a5103f4 | 2014-02-04 11:20:14 +1100 | [diff] [blame] | 165 | explicit_bzero(sigblob, diff); |
Ben Lindstrom | ceae9d1 | 2002-06-06 20:55:04 +0000 | [diff] [blame] | 166 | len = modlen; |
| 167 | } |
Damien Miller | b3051d0 | 2014-01-10 10:58:53 +1100 | [diff] [blame] | 168 | hash_alg = SSH_DIGEST_SHA1; |
| 169 | if ((dlen = ssh_digest_bytes(hash_alg)) == 0) { |
Damien Miller | 8668706 | 2014-07-02 15:28:02 +1000 | [diff] [blame] | 170 | ret = SSH_ERR_INTERNAL_ERROR; |
| 171 | goto out; |
Ben Lindstrom | 425fb02 | 2001-03-29 00:31:20 +0000 | [diff] [blame] | 172 | } |
Damien Miller | 8668706 | 2014-07-02 15:28:02 +1000 | [diff] [blame] | 173 | if ((ret = ssh_digest_memory(hash_alg, data, datalen, |
| 174 | digest, sizeof(digest))) != 0) |
| 175 | goto out; |
Damien Miller | 0bc1bd8 | 2000-11-13 22:57:25 +1100 | [diff] [blame] | 176 | |
Damien Miller | b3051d0 | 2014-01-10 10:58:53 +1100 | [diff] [blame] | 177 | ret = openssh_RSA_verify(hash_alg, digest, dlen, sigblob, len, |
| 178 | key->rsa); |
Damien Miller | 8668706 | 2014-07-02 15:28:02 +1000 | [diff] [blame] | 179 | out: |
| 180 | if (sigblob != NULL) { |
| 181 | explicit_bzero(sigblob, len); |
| 182 | free(sigblob); |
| 183 | } |
| 184 | if (ktype != NULL) |
| 185 | free(ktype); |
| 186 | if (b != NULL) |
| 187 | sshbuf_free(b); |
Damien Miller | a5103f4 | 2014-02-04 11:20:14 +1100 | [diff] [blame] | 188 | explicit_bzero(digest, sizeof(digest)); |
Damien Miller | 0bc1bd8 | 2000-11-13 22:57:25 +1100 | [diff] [blame] | 189 | return ret; |
| 190 | } |
Ben Lindstrom | 0deb5d9 | 2002-08-20 18:40:03 +0000 | [diff] [blame] | 191 | |
| 192 | /* |
| 193 | * See: |
| 194 | * http://www.rsasecurity.com/rsalabs/pkcs/pkcs-1/ |
| 195 | * ftp://ftp.rsasecurity.com/pub/pkcs/pkcs-1/pkcs-1v2-1.asn |
| 196 | */ |
| 197 | /* |
| 198 | * id-sha1 OBJECT IDENTIFIER ::= { iso(1) identified-organization(3) |
| 199 | * oiw(14) secsig(3) algorithms(2) 26 } |
| 200 | */ |
| 201 | static const u_char id_sha1[] = { |
| 202 | 0x30, 0x21, /* type Sequence, length 0x21 (33) */ |
| 203 | 0x30, 0x09, /* type Sequence, length 0x09 */ |
| 204 | 0x06, 0x05, /* type OID, length 0x05 */ |
| 205 | 0x2b, 0x0e, 0x03, 0x02, 0x1a, /* id-sha1 OID */ |
| 206 | 0x05, 0x00, /* NULL */ |
| 207 | 0x04, 0x14 /* Octet string, length 0x14 (20), followed by sha1 hash */ |
| 208 | }; |
Ben Lindstrom | 0deb5d9 | 2002-08-20 18:40:03 +0000 | [diff] [blame] | 209 | |
| 210 | static int |
Damien Miller | 8668706 | 2014-07-02 15:28:02 +1000 | [diff] [blame] | 211 | openssh_RSA_verify(int hash_alg, u_char *hash, size_t hashlen, |
| 212 | u_char *sigbuf, size_t siglen, RSA *rsa) |
Ben Lindstrom | 0deb5d9 | 2002-08-20 18:40:03 +0000 | [diff] [blame] | 213 | { |
Damien Miller | 8668706 | 2014-07-02 15:28:02 +1000 | [diff] [blame] | 214 | size_t ret, rsasize = 0, oidlen = 0, hlen = 0; |
Damien Miller | 4e8285e | 2010-08-03 16:04:03 +1000 | [diff] [blame] | 215 | int len, oidmatch, hashmatch; |
Ben Lindstrom | 0deb5d9 | 2002-08-20 18:40:03 +0000 | [diff] [blame] | 216 | const u_char *oid = NULL; |
| 217 | u_char *decrypted = NULL; |
| 218 | |
Damien Miller | 8668706 | 2014-07-02 15:28:02 +1000 | [diff] [blame] | 219 | ret = SSH_ERR_INTERNAL_ERROR; |
Damien Miller | b3051d0 | 2014-01-10 10:58:53 +1100 | [diff] [blame] | 220 | switch (hash_alg) { |
| 221 | case SSH_DIGEST_SHA1: |
Ben Lindstrom | 0deb5d9 | 2002-08-20 18:40:03 +0000 | [diff] [blame] | 222 | oid = id_sha1; |
| 223 | oidlen = sizeof(id_sha1); |
| 224 | hlen = 20; |
| 225 | break; |
Ben Lindstrom | 0deb5d9 | 2002-08-20 18:40:03 +0000 | [diff] [blame] | 226 | default: |
| 227 | goto done; |
Ben Lindstrom | 0deb5d9 | 2002-08-20 18:40:03 +0000 | [diff] [blame] | 228 | } |
| 229 | if (hashlen != hlen) { |
Damien Miller | 8668706 | 2014-07-02 15:28:02 +1000 | [diff] [blame] | 230 | ret = SSH_ERR_INVALID_ARGUMENT; |
Ben Lindstrom | 0deb5d9 | 2002-08-20 18:40:03 +0000 | [diff] [blame] | 231 | goto done; |
| 232 | } |
| 233 | rsasize = RSA_size(rsa); |
Damien Miller | 8668706 | 2014-07-02 15:28:02 +1000 | [diff] [blame] | 234 | if (rsasize <= 0 || rsasize > SSHBUF_MAX_BIGNUM || |
| 235 | siglen == 0 || siglen > rsasize) { |
| 236 | ret = SSH_ERR_INVALID_ARGUMENT; |
Ben Lindstrom | 0deb5d9 | 2002-08-20 18:40:03 +0000 | [diff] [blame] | 237 | goto done; |
| 238 | } |
Damien Miller | 8668706 | 2014-07-02 15:28:02 +1000 | [diff] [blame] | 239 | if ((decrypted = malloc(rsasize)) == NULL) { |
| 240 | ret = SSH_ERR_ALLOC_FAIL; |
| 241 | goto done; |
| 242 | } |
Ben Lindstrom | 0deb5d9 | 2002-08-20 18:40:03 +0000 | [diff] [blame] | 243 | if ((len = RSA_public_decrypt(siglen, sigbuf, decrypted, rsa, |
| 244 | RSA_PKCS1_PADDING)) < 0) { |
Damien Miller | 8668706 | 2014-07-02 15:28:02 +1000 | [diff] [blame] | 245 | ret = SSH_ERR_LIBCRYPTO_ERROR; |
Ben Lindstrom | 0deb5d9 | 2002-08-20 18:40:03 +0000 | [diff] [blame] | 246 | goto done; |
| 247 | } |
Damien Miller | 8668706 | 2014-07-02 15:28:02 +1000 | [diff] [blame] | 248 | if (len < 0 || (size_t)len != hlen + oidlen) { |
| 249 | ret = SSH_ERR_INVALID_FORMAT; |
Ben Lindstrom | 0deb5d9 | 2002-08-20 18:40:03 +0000 | [diff] [blame] | 250 | goto done; |
| 251 | } |
Damien Miller | 4e8285e | 2010-08-03 16:04:03 +1000 | [diff] [blame] | 252 | oidmatch = timingsafe_bcmp(decrypted, oid, oidlen) == 0; |
| 253 | hashmatch = timingsafe_bcmp(decrypted + oidlen, hash, hlen) == 0; |
Damien Miller | 8668706 | 2014-07-02 15:28:02 +1000 | [diff] [blame] | 254 | if (!oidmatch || !hashmatch) { |
| 255 | ret = SSH_ERR_SIGNATURE_INVALID; |
Ben Lindstrom | 0deb5d9 | 2002-08-20 18:40:03 +0000 | [diff] [blame] | 256 | goto done; |
| 257 | } |
Damien Miller | 8668706 | 2014-07-02 15:28:02 +1000 | [diff] [blame] | 258 | ret = 0; |
Ben Lindstrom | 0deb5d9 | 2002-08-20 18:40:03 +0000 | [diff] [blame] | 259 | done: |
Damien Miller | 8668706 | 2014-07-02 15:28:02 +1000 | [diff] [blame] | 260 | if (decrypted) { |
| 261 | explicit_bzero(decrypted, rsasize); |
| 262 | free(decrypted); |
| 263 | } |
Ben Lindstrom | 0deb5d9 | 2002-08-20 18:40:03 +0000 | [diff] [blame] | 264 | return ret; |
| 265 | } |