djm@openbsd.org | 04c091f | 2019-01-19 21:43:56 +0000 | [diff] [blame] | 1 | /* $OpenBSD: ssh_api.c,v 1.10 2019/01/19 21:43:56 djm Exp $ */ |
markus@openbsd.org | f582f0e | 2015-01-19 20:30:23 +0000 | [diff] [blame] | 2 | /* |
| 3 | * Copyright (c) 2012 Markus Friedl. All rights reserved. |
| 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 | |
markus@openbsd.org | f582f0e | 2015-01-19 20:30:23 +0000 | [diff] [blame] | 20 | #include "ssh_api.h" |
| 21 | #include "compat.h" |
| 22 | #include "log.h" |
| 23 | #include "authfile.h" |
| 24 | #include "sshkey.h" |
| 25 | #include "misc.h" |
markus@openbsd.org | f582f0e | 2015-01-19 20:30:23 +0000 | [diff] [blame] | 26 | #include "ssh2.h" |
| 27 | #include "version.h" |
| 28 | #include "myproposal.h" |
| 29 | #include "ssherr.h" |
| 30 | #include "sshbuf.h" |
| 31 | |
Darren Tucker | 31b4952 | 2018-10-22 20:05:18 +1100 | [diff] [blame] | 32 | #include "openbsd-compat/openssl-compat.h" |
| 33 | |
markus@openbsd.org | f582f0e | 2015-01-19 20:30:23 +0000 | [diff] [blame] | 34 | #include <string.h> |
| 35 | |
| 36 | int _ssh_exchange_banner(struct ssh *); |
djm@openbsd.org | 0a843d9 | 2018-12-27 03:25:24 +0000 | [diff] [blame] | 37 | int _ssh_send_banner(struct ssh *, struct sshbuf *); |
| 38 | int _ssh_read_banner(struct ssh *, struct sshbuf *); |
markus@openbsd.org | f582f0e | 2015-01-19 20:30:23 +0000 | [diff] [blame] | 39 | int _ssh_order_hostkeyalgs(struct ssh *); |
| 40 | int _ssh_verify_host_key(struct sshkey *, struct ssh *); |
djm@openbsd.org | 5104db7 | 2015-01-26 06:10:03 +0000 | [diff] [blame] | 41 | struct sshkey *_ssh_host_public_key(int, int, struct ssh *); |
| 42 | struct sshkey *_ssh_host_private_key(int, int, struct ssh *); |
djm@openbsd.org | 04c091f | 2019-01-19 21:43:56 +0000 | [diff] [blame] | 43 | int _ssh_host_key_sign(struct ssh *, struct sshkey *, struct sshkey *, |
| 44 | u_char **, size_t *, const u_char *, size_t, const char *); |
markus@openbsd.org | f582f0e | 2015-01-19 20:30:23 +0000 | [diff] [blame] | 45 | |
| 46 | /* |
| 47 | * stubs for the server side implementation of kex. |
| 48 | * disable privsep so our stubs will never be called. |
| 49 | */ |
| 50 | int use_privsep = 0; |
| 51 | int mm_sshkey_sign(struct sshkey *, u_char **, u_int *, |
markus@openbsd.org | 76c9fbb | 2015-12-04 16:41:28 +0000 | [diff] [blame] | 52 | u_char *, u_int, char *, u_int); |
markus@openbsd.org | f582f0e | 2015-01-19 20:30:23 +0000 | [diff] [blame] | 53 | DH *mm_choose_dh(int, int, int); |
| 54 | |
| 55 | /* Define these two variables here so that they are part of the library */ |
| 56 | u_char *session_id2 = NULL; |
| 57 | u_int session_id2_len = 0; |
| 58 | |
| 59 | int |
| 60 | mm_sshkey_sign(struct sshkey *key, u_char **sigp, u_int *lenp, |
markus@openbsd.org | 76c9fbb | 2015-12-04 16:41:28 +0000 | [diff] [blame] | 61 | u_char *data, u_int datalen, char *alg, u_int compat) |
markus@openbsd.org | f582f0e | 2015-01-19 20:30:23 +0000 | [diff] [blame] | 62 | { |
| 63 | return (-1); |
| 64 | } |
| 65 | |
| 66 | DH * |
| 67 | mm_choose_dh(int min, int nbits, int max) |
| 68 | { |
| 69 | return (NULL); |
| 70 | } |
| 71 | |
| 72 | /* API */ |
| 73 | |
| 74 | int |
| 75 | ssh_init(struct ssh **sshp, int is_server, struct kex_params *kex_params) |
| 76 | { |
| 77 | char *myproposal[PROPOSAL_MAX] = { KEX_CLIENT }; |
| 78 | struct ssh *ssh; |
| 79 | char **proposal; |
| 80 | static int called; |
| 81 | int r; |
| 82 | |
| 83 | if (!called) { |
Damien Miller | 42c5ec4 | 2018-11-23 10:40:06 +1100 | [diff] [blame] | 84 | seed_rng(); |
markus@openbsd.org | f582f0e | 2015-01-19 20:30:23 +0000 | [diff] [blame] | 85 | called = 1; |
| 86 | } |
| 87 | |
djm@openbsd.org | 4509b5d | 2015-01-30 01:13:33 +0000 | [diff] [blame] | 88 | if ((ssh = ssh_packet_set_connection(NULL, -1, -1)) == NULL) |
| 89 | return SSH_ERR_ALLOC_FAIL; |
markus@openbsd.org | f582f0e | 2015-01-19 20:30:23 +0000 | [diff] [blame] | 90 | if (is_server) |
| 91 | ssh_packet_set_server(ssh); |
| 92 | |
| 93 | /* Initialize key exchange */ |
| 94 | proposal = kex_params ? kex_params->proposal : myproposal; |
djm@openbsd.org | 0a843d9 | 2018-12-27 03:25:24 +0000 | [diff] [blame] | 95 | if ((r = kex_ready(ssh, proposal)) != 0) { |
markus@openbsd.org | f582f0e | 2015-01-19 20:30:23 +0000 | [diff] [blame] | 96 | ssh_free(ssh); |
| 97 | return r; |
| 98 | } |
| 99 | ssh->kex->server = is_server; |
| 100 | if (is_server) { |
| 101 | #ifdef WITH_OPENSSL |
| 102 | ssh->kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server; |
| 103 | ssh->kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server; |
djm@openbsd.org | 0e8eeec | 2016-05-02 10:26:04 +0000 | [diff] [blame] | 104 | ssh->kex->kex[KEX_DH_GRP14_SHA256] = kexdh_server; |
| 105 | ssh->kex->kex[KEX_DH_GRP16_SHA512] = kexdh_server; |
| 106 | ssh->kex->kex[KEX_DH_GRP18_SHA512] = kexdh_server; |
markus@openbsd.org | f582f0e | 2015-01-19 20:30:23 +0000 | [diff] [blame] | 107 | ssh->kex->kex[KEX_DH_GEX_SHA1] = kexgex_server; |
| 108 | ssh->kex->kex[KEX_DH_GEX_SHA256] = kexgex_server; |
Darren Tucker | f2004cd | 2015-02-23 05:04:21 +1100 | [diff] [blame] | 109 | # ifdef OPENSSL_HAS_ECC |
markus@openbsd.org | f582f0e | 2015-01-19 20:30:23 +0000 | [diff] [blame] | 110 | ssh->kex->kex[KEX_ECDH_SHA2] = kexecdh_server; |
Darren Tucker | f2004cd | 2015-02-23 05:04:21 +1100 | [diff] [blame] | 111 | # endif |
markus@openbsd.org | f582f0e | 2015-01-19 20:30:23 +0000 | [diff] [blame] | 112 | #endif /* WITH_OPENSSL */ |
| 113 | ssh->kex->kex[KEX_C25519_SHA256] = kexc25519_server; |
| 114 | ssh->kex->load_host_public_key=&_ssh_host_public_key; |
| 115 | ssh->kex->load_host_private_key=&_ssh_host_private_key; |
| 116 | ssh->kex->sign=&_ssh_host_key_sign; |
| 117 | } else { |
| 118 | #ifdef WITH_OPENSSL |
| 119 | ssh->kex->kex[KEX_DH_GRP1_SHA1] = kexdh_client; |
| 120 | ssh->kex->kex[KEX_DH_GRP14_SHA1] = kexdh_client; |
djm@openbsd.org | 0e8eeec | 2016-05-02 10:26:04 +0000 | [diff] [blame] | 121 | ssh->kex->kex[KEX_DH_GRP14_SHA256] = kexdh_client; |
| 122 | ssh->kex->kex[KEX_DH_GRP16_SHA512] = kexdh_client; |
| 123 | ssh->kex->kex[KEX_DH_GRP18_SHA512] = kexdh_client; |
markus@openbsd.org | f582f0e | 2015-01-19 20:30:23 +0000 | [diff] [blame] | 124 | ssh->kex->kex[KEX_DH_GEX_SHA1] = kexgex_client; |
| 125 | ssh->kex->kex[KEX_DH_GEX_SHA256] = kexgex_client; |
Darren Tucker | f2004cd | 2015-02-23 05:04:21 +1100 | [diff] [blame] | 126 | # ifdef OPENSSL_HAS_ECC |
markus@openbsd.org | f582f0e | 2015-01-19 20:30:23 +0000 | [diff] [blame] | 127 | ssh->kex->kex[KEX_ECDH_SHA2] = kexecdh_client; |
Darren Tucker | f2004cd | 2015-02-23 05:04:21 +1100 | [diff] [blame] | 128 | # endif |
markus@openbsd.org | f582f0e | 2015-01-19 20:30:23 +0000 | [diff] [blame] | 129 | #endif /* WITH_OPENSSL */ |
| 130 | ssh->kex->kex[KEX_C25519_SHA256] = kexc25519_client; |
| 131 | ssh->kex->verify_host_key =&_ssh_verify_host_key; |
| 132 | } |
| 133 | *sshp = ssh; |
| 134 | return 0; |
| 135 | } |
| 136 | |
| 137 | void |
| 138 | ssh_free(struct ssh *ssh) |
| 139 | { |
| 140 | struct key_entry *k; |
| 141 | |
| 142 | ssh_packet_close(ssh); |
| 143 | /* |
| 144 | * we've only created the public keys variants in case we |
| 145 | * are a acting as a server. |
| 146 | */ |
| 147 | while ((k = TAILQ_FIRST(&ssh->public_keys)) != NULL) { |
| 148 | TAILQ_REMOVE(&ssh->public_keys, k, next); |
| 149 | if (ssh->kex && ssh->kex->server) |
| 150 | sshkey_free(k->key); |
| 151 | free(k); |
| 152 | } |
| 153 | while ((k = TAILQ_FIRST(&ssh->private_keys)) != NULL) { |
| 154 | TAILQ_REMOVE(&ssh->private_keys, k, next); |
| 155 | free(k); |
| 156 | } |
| 157 | if (ssh->kex) |
| 158 | kex_free(ssh->kex); |
| 159 | free(ssh); |
| 160 | } |
| 161 | |
| 162 | void |
| 163 | ssh_set_app_data(struct ssh *ssh, void *app_data) |
| 164 | { |
| 165 | ssh->app_data = app_data; |
| 166 | } |
| 167 | |
| 168 | void * |
| 169 | ssh_get_app_data(struct ssh *ssh) |
| 170 | { |
| 171 | return ssh->app_data; |
| 172 | } |
| 173 | |
| 174 | /* Returns < 0 on error, 0 otherwise */ |
| 175 | int |
| 176 | ssh_add_hostkey(struct ssh *ssh, struct sshkey *key) |
| 177 | { |
| 178 | struct sshkey *pubkey = NULL; |
| 179 | struct key_entry *k = NULL, *k_prv = NULL; |
| 180 | int r; |
| 181 | |
| 182 | if (ssh->kex->server) { |
| 183 | if ((r = sshkey_from_private(key, &pubkey)) != 0) |
| 184 | return r; |
| 185 | if ((k = malloc(sizeof(*k))) == NULL || |
| 186 | (k_prv = malloc(sizeof(*k_prv))) == NULL) { |
| 187 | free(k); |
| 188 | sshkey_free(pubkey); |
| 189 | return SSH_ERR_ALLOC_FAIL; |
| 190 | } |
| 191 | k_prv->key = key; |
| 192 | TAILQ_INSERT_TAIL(&ssh->private_keys, k_prv, next); |
| 193 | |
| 194 | /* add the public key, too */ |
| 195 | k->key = pubkey; |
| 196 | TAILQ_INSERT_TAIL(&ssh->public_keys, k, next); |
| 197 | r = 0; |
| 198 | } else { |
| 199 | if ((k = malloc(sizeof(*k))) == NULL) |
| 200 | return SSH_ERR_ALLOC_FAIL; |
| 201 | k->key = key; |
| 202 | TAILQ_INSERT_TAIL(&ssh->public_keys, k, next); |
| 203 | r = 0; |
| 204 | } |
| 205 | |
| 206 | return r; |
| 207 | } |
| 208 | |
| 209 | int |
| 210 | ssh_set_verify_host_key_callback(struct ssh *ssh, |
| 211 | int (*cb)(struct sshkey *, struct ssh *)) |
| 212 | { |
| 213 | if (cb == NULL || ssh->kex == NULL) |
| 214 | return SSH_ERR_INVALID_ARGUMENT; |
| 215 | |
| 216 | ssh->kex->verify_host_key = cb; |
| 217 | |
| 218 | return 0; |
| 219 | } |
| 220 | |
| 221 | int |
| 222 | ssh_input_append(struct ssh *ssh, const u_char *data, size_t len) |
| 223 | { |
| 224 | return sshbuf_put(ssh_packet_get_input(ssh), data, len); |
| 225 | } |
| 226 | |
| 227 | int |
| 228 | ssh_packet_next(struct ssh *ssh, u_char *typep) |
| 229 | { |
| 230 | int r; |
| 231 | u_int32_t seqnr; |
| 232 | u_char type; |
| 233 | |
| 234 | /* |
| 235 | * Try to read a packet. Return SSH_MSG_NONE if no packet or not |
| 236 | * enough data. |
| 237 | */ |
| 238 | *typep = SSH_MSG_NONE; |
djm@openbsd.org | 0a843d9 | 2018-12-27 03:25:24 +0000 | [diff] [blame] | 239 | if (sshbuf_len(ssh->kex->client_version) == 0 || |
| 240 | sshbuf_len(ssh->kex->server_version) == 0) |
markus@openbsd.org | f582f0e | 2015-01-19 20:30:23 +0000 | [diff] [blame] | 241 | return _ssh_exchange_banner(ssh); |
| 242 | /* |
| 243 | * If we enough data and a dispatch function then |
| 244 | * call the function and get the next packet. |
| 245 | * Otherwise return the packet type to the caller so it |
| 246 | * can decide how to go on. |
| 247 | * |
| 248 | * We will only call the dispatch function for: |
| 249 | * 20-29 Algorithm negotiation |
| 250 | * 30-49 Key exchange method specific (numbers can be reused for |
| 251 | * different authentication methods) |
| 252 | */ |
| 253 | for (;;) { |
| 254 | if ((r = ssh_packet_read_poll2(ssh, &type, &seqnr)) != 0) |
| 255 | return r; |
| 256 | if (type > 0 && type < DISPATCH_MAX && |
| 257 | type >= SSH2_MSG_KEXINIT && type <= SSH2_MSG_TRANSPORT_MAX && |
| 258 | ssh->dispatch[type] != NULL) { |
| 259 | if ((r = (*ssh->dispatch[type])(type, seqnr, ssh)) != 0) |
| 260 | return r; |
| 261 | } else { |
| 262 | *typep = type; |
| 263 | return 0; |
| 264 | } |
| 265 | } |
| 266 | } |
| 267 | |
| 268 | const u_char * |
| 269 | ssh_packet_payload(struct ssh *ssh, size_t *lenp) |
| 270 | { |
| 271 | return sshpkt_ptr(ssh, lenp); |
| 272 | } |
| 273 | |
| 274 | int |
| 275 | ssh_packet_put(struct ssh *ssh, int type, const u_char *data, size_t len) |
| 276 | { |
| 277 | int r; |
| 278 | |
| 279 | if ((r = sshpkt_start(ssh, type)) != 0 || |
| 280 | (r = sshpkt_put(ssh, data, len)) != 0 || |
| 281 | (r = sshpkt_send(ssh)) != 0) |
| 282 | return r; |
| 283 | return 0; |
| 284 | } |
| 285 | |
| 286 | const u_char * |
| 287 | ssh_output_ptr(struct ssh *ssh, size_t *len) |
| 288 | { |
| 289 | struct sshbuf *output = ssh_packet_get_output(ssh); |
| 290 | |
| 291 | *len = sshbuf_len(output); |
| 292 | return sshbuf_ptr(output); |
| 293 | } |
| 294 | |
| 295 | int |
| 296 | ssh_output_consume(struct ssh *ssh, size_t len) |
| 297 | { |
| 298 | return sshbuf_consume(ssh_packet_get_output(ssh), len); |
| 299 | } |
| 300 | |
| 301 | int |
| 302 | ssh_output_space(struct ssh *ssh, size_t len) |
| 303 | { |
| 304 | return (0 == sshbuf_check_reserve(ssh_packet_get_output(ssh), len)); |
| 305 | } |
| 306 | |
| 307 | int |
| 308 | ssh_input_space(struct ssh *ssh, size_t len) |
| 309 | { |
| 310 | return (0 == sshbuf_check_reserve(ssh_packet_get_input(ssh), len)); |
| 311 | } |
| 312 | |
| 313 | /* Read other side's version identification. */ |
| 314 | int |
djm@openbsd.org | 0a843d9 | 2018-12-27 03:25:24 +0000 | [diff] [blame] | 315 | _ssh_read_banner(struct ssh *ssh, struct sshbuf *banner) |
markus@openbsd.org | f582f0e | 2015-01-19 20:30:23 +0000 | [diff] [blame] | 316 | { |
djm@openbsd.org | 0a843d9 | 2018-12-27 03:25:24 +0000 | [diff] [blame] | 317 | struct sshbuf *input = ssh_packet_get_input(ssh); |
markus@openbsd.org | f582f0e | 2015-01-19 20:30:23 +0000 | [diff] [blame] | 318 | const char *mismatch = "Protocol mismatch.\r\n"; |
djm@openbsd.org | 0a843d9 | 2018-12-27 03:25:24 +0000 | [diff] [blame] | 319 | const u_char *s = sshbuf_ptr(input); |
| 320 | u_char c; |
| 321 | char *cp, *remote_version; |
| 322 | int r, remote_major, remote_minor, expect_nl; |
| 323 | size_t n, j; |
markus@openbsd.org | f582f0e | 2015-01-19 20:30:23 +0000 | [diff] [blame] | 324 | |
markus@openbsd.org | f582f0e | 2015-01-19 20:30:23 +0000 | [diff] [blame] | 325 | for (j = n = 0;;) { |
djm@openbsd.org | 0a843d9 | 2018-12-27 03:25:24 +0000 | [diff] [blame] | 326 | sshbuf_reset(banner); |
| 327 | expect_nl = 0; |
| 328 | for (;;) { |
| 329 | if (j >= sshbuf_len(input)) |
| 330 | return 0; /* insufficient data in input buf */ |
| 331 | c = s[j++]; |
| 332 | if (c == '\r') { |
| 333 | expect_nl = 1; |
| 334 | continue; |
markus@openbsd.org | f582f0e | 2015-01-19 20:30:23 +0000 | [diff] [blame] | 335 | } |
djm@openbsd.org | 0a843d9 | 2018-12-27 03:25:24 +0000 | [diff] [blame] | 336 | if (c == '\n') |
markus@openbsd.org | f582f0e | 2015-01-19 20:30:23 +0000 | [diff] [blame] | 337 | break; |
djm@openbsd.org | 0a843d9 | 2018-12-27 03:25:24 +0000 | [diff] [blame] | 338 | if (expect_nl) |
| 339 | goto bad; |
| 340 | if ((r = sshbuf_put_u8(banner, c)) != 0) |
| 341 | return r; |
| 342 | if (sshbuf_len(banner) > SSH_MAX_BANNER_LEN) |
| 343 | goto bad; |
markus@openbsd.org | f582f0e | 2015-01-19 20:30:23 +0000 | [diff] [blame] | 344 | } |
djm@openbsd.org | 0a843d9 | 2018-12-27 03:25:24 +0000 | [diff] [blame] | 345 | if (sshbuf_len(banner) >= 4 && |
| 346 | memcmp(sshbuf_ptr(banner), "SSH-", 4) == 0) |
markus@openbsd.org | f582f0e | 2015-01-19 20:30:23 +0000 | [diff] [blame] | 347 | break; |
djm@openbsd.org | 0a843d9 | 2018-12-27 03:25:24 +0000 | [diff] [blame] | 348 | if ((cp = sshbuf_dup_string(banner)) == NULL) |
| 349 | return SSH_ERR_ALLOC_FAIL; |
| 350 | debug("%s: %s", __func__, cp); |
| 351 | free(cp); |
| 352 | /* Accept lines before banner only on client */ |
| 353 | if (ssh->kex->server || ++n > SSH_MAX_PRE_BANNER_LINES) { |
| 354 | bad: |
markus@openbsd.org | f582f0e | 2015-01-19 20:30:23 +0000 | [diff] [blame] | 355 | if ((r = sshbuf_put(ssh_packet_get_output(ssh), |
| 356 | mismatch, strlen(mismatch))) != 0) |
| 357 | return r; |
| 358 | return SSH_ERR_NO_PROTOCOL_VERSION; |
| 359 | } |
| 360 | } |
| 361 | if ((r = sshbuf_consume(input, j)) != 0) |
| 362 | return r; |
| 363 | |
djm@openbsd.org | 0a843d9 | 2018-12-27 03:25:24 +0000 | [diff] [blame] | 364 | if ((cp = sshbuf_dup_string(banner)) == NULL) |
| 365 | return SSH_ERR_ALLOC_FAIL; |
| 366 | /* XXX remote version must be the same size as banner for sscanf */ |
| 367 | if ((remote_version = calloc(1, sshbuf_len(banner))) == NULL) |
| 368 | return SSH_ERR_ALLOC_FAIL; |
| 369 | |
markus@openbsd.org | f582f0e | 2015-01-19 20:30:23 +0000 | [diff] [blame] | 370 | /* |
| 371 | * Check that the versions match. In future this might accept |
| 372 | * several versions and set appropriate flags to handle them. |
| 373 | */ |
djm@openbsd.org | 0a843d9 | 2018-12-27 03:25:24 +0000 | [diff] [blame] | 374 | if (sscanf(cp, "SSH-%d.%d-%[^\n]\n", |
markus@openbsd.org | f582f0e | 2015-01-19 20:30:23 +0000 | [diff] [blame] | 375 | &remote_major, &remote_minor, remote_version) != 3) |
| 376 | return SSH_ERR_INVALID_FORMAT; |
| 377 | debug("Remote protocol version %d.%d, remote software version %.100s", |
| 378 | remote_major, remote_minor, remote_version); |
| 379 | |
| 380 | ssh->compat = compat_datafellows(remote_version); |
| 381 | if (remote_major == 1 && remote_minor == 99) { |
| 382 | remote_major = 2; |
| 383 | remote_minor = 0; |
| 384 | } |
| 385 | if (remote_major != 2) |
| 386 | return SSH_ERR_PROTOCOL_MISMATCH; |
djm@openbsd.org | 0a843d9 | 2018-12-27 03:25:24 +0000 | [diff] [blame] | 387 | debug("Remote version string %.100s", cp); |
| 388 | free(cp); |
markus@openbsd.org | f582f0e | 2015-01-19 20:30:23 +0000 | [diff] [blame] | 389 | return 0; |
| 390 | } |
| 391 | |
| 392 | /* Send our own protocol version identification. */ |
| 393 | int |
djm@openbsd.org | 0a843d9 | 2018-12-27 03:25:24 +0000 | [diff] [blame] | 394 | _ssh_send_banner(struct ssh *ssh, struct sshbuf *banner) |
markus@openbsd.org | f582f0e | 2015-01-19 20:30:23 +0000 | [diff] [blame] | 395 | { |
djm@openbsd.org | 0a843d9 | 2018-12-27 03:25:24 +0000 | [diff] [blame] | 396 | char *cp; |
markus@openbsd.org | f582f0e | 2015-01-19 20:30:23 +0000 | [diff] [blame] | 397 | int r; |
| 398 | |
djm@openbsd.org | 0a843d9 | 2018-12-27 03:25:24 +0000 | [diff] [blame] | 399 | if ((r = sshbuf_putf(banner, "SSH-2.0-%.100s\r\n", SSH_VERSION)) != 0) |
markus@openbsd.org | f582f0e | 2015-01-19 20:30:23 +0000 | [diff] [blame] | 400 | return r; |
djm@openbsd.org | 0a843d9 | 2018-12-27 03:25:24 +0000 | [diff] [blame] | 401 | if ((r = sshbuf_putb(ssh_packet_get_output(ssh), banner)) != 0) |
| 402 | return r; |
| 403 | /* Remove trailing \r\n */ |
| 404 | if ((r = sshbuf_consume_end(banner, 2)) != 0) |
| 405 | return r; |
| 406 | if ((cp = sshbuf_dup_string(banner)) == NULL) |
markus@openbsd.org | f582f0e | 2015-01-19 20:30:23 +0000 | [diff] [blame] | 407 | return SSH_ERR_ALLOC_FAIL; |
djm@openbsd.org | 0a843d9 | 2018-12-27 03:25:24 +0000 | [diff] [blame] | 408 | debug("Local version string %.100s", cp); |
| 409 | free(cp); |
markus@openbsd.org | f582f0e | 2015-01-19 20:30:23 +0000 | [diff] [blame] | 410 | return 0; |
| 411 | } |
| 412 | |
| 413 | int |
| 414 | _ssh_exchange_banner(struct ssh *ssh) |
| 415 | { |
| 416 | struct kex *kex = ssh->kex; |
| 417 | int r; |
| 418 | |
| 419 | /* |
| 420 | * if _ssh_read_banner() cannot parse a full version string |
| 421 | * it will return NULL and we end up calling it again. |
| 422 | */ |
| 423 | |
| 424 | r = 0; |
| 425 | if (kex->server) { |
djm@openbsd.org | 0a843d9 | 2018-12-27 03:25:24 +0000 | [diff] [blame] | 426 | if (sshbuf_len(ssh->kex->server_version) == 0) |
| 427 | r = _ssh_send_banner(ssh, ssh->kex->server_version); |
markus@openbsd.org | f582f0e | 2015-01-19 20:30:23 +0000 | [diff] [blame] | 428 | if (r == 0 && |
djm@openbsd.org | 0a843d9 | 2018-12-27 03:25:24 +0000 | [diff] [blame] | 429 | sshbuf_len(ssh->kex->server_version) != 0 && |
| 430 | sshbuf_len(ssh->kex->client_version) == 0) |
| 431 | r = _ssh_read_banner(ssh, ssh->kex->client_version); |
markus@openbsd.org | f582f0e | 2015-01-19 20:30:23 +0000 | [diff] [blame] | 432 | } else { |
djm@openbsd.org | 0a843d9 | 2018-12-27 03:25:24 +0000 | [diff] [blame] | 433 | if (sshbuf_len(ssh->kex->server_version) == 0) |
| 434 | r = _ssh_read_banner(ssh, ssh->kex->server_version); |
markus@openbsd.org | f582f0e | 2015-01-19 20:30:23 +0000 | [diff] [blame] | 435 | if (r == 0 && |
djm@openbsd.org | 0a843d9 | 2018-12-27 03:25:24 +0000 | [diff] [blame] | 436 | sshbuf_len(ssh->kex->server_version) != 0 && |
| 437 | sshbuf_len(ssh->kex->client_version) == 0) |
| 438 | r = _ssh_send_banner(ssh, ssh->kex->client_version); |
markus@openbsd.org | f582f0e | 2015-01-19 20:30:23 +0000 | [diff] [blame] | 439 | } |
| 440 | if (r != 0) |
| 441 | return r; |
| 442 | /* start initial kex as soon as we have exchanged the banners */ |
djm@openbsd.org | 0a843d9 | 2018-12-27 03:25:24 +0000 | [diff] [blame] | 443 | if (sshbuf_len(ssh->kex->server_version) != 0 && |
| 444 | sshbuf_len(ssh->kex->client_version) != 0) { |
markus@openbsd.org | f582f0e | 2015-01-19 20:30:23 +0000 | [diff] [blame] | 445 | if ((r = _ssh_order_hostkeyalgs(ssh)) != 0 || |
| 446 | (r = kex_send_kexinit(ssh)) != 0) |
| 447 | return r; |
| 448 | } |
| 449 | return 0; |
| 450 | } |
| 451 | |
| 452 | struct sshkey * |
djm@openbsd.org | 5104db7 | 2015-01-26 06:10:03 +0000 | [diff] [blame] | 453 | _ssh_host_public_key(int type, int nid, struct ssh *ssh) |
markus@openbsd.org | f582f0e | 2015-01-19 20:30:23 +0000 | [diff] [blame] | 454 | { |
| 455 | struct key_entry *k; |
| 456 | |
| 457 | debug3("%s: need %d", __func__, type); |
| 458 | TAILQ_FOREACH(k, &ssh->public_keys, next) { |
| 459 | debug3("%s: check %s", __func__, sshkey_type(k->key)); |
djm@openbsd.org | 5104db7 | 2015-01-26 06:10:03 +0000 | [diff] [blame] | 460 | if (k->key->type == type && |
| 461 | (type != KEY_ECDSA || k->key->ecdsa_nid == nid)) |
markus@openbsd.org | f582f0e | 2015-01-19 20:30:23 +0000 | [diff] [blame] | 462 | return (k->key); |
| 463 | } |
| 464 | return (NULL); |
| 465 | } |
| 466 | |
| 467 | struct sshkey * |
djm@openbsd.org | 5104db7 | 2015-01-26 06:10:03 +0000 | [diff] [blame] | 468 | _ssh_host_private_key(int type, int nid, struct ssh *ssh) |
markus@openbsd.org | f582f0e | 2015-01-19 20:30:23 +0000 | [diff] [blame] | 469 | { |
| 470 | struct key_entry *k; |
| 471 | |
| 472 | debug3("%s: need %d", __func__, type); |
| 473 | TAILQ_FOREACH(k, &ssh->private_keys, next) { |
| 474 | debug3("%s: check %s", __func__, sshkey_type(k->key)); |
djm@openbsd.org | 5104db7 | 2015-01-26 06:10:03 +0000 | [diff] [blame] | 475 | if (k->key->type == type && |
| 476 | (type != KEY_ECDSA || k->key->ecdsa_nid == nid)) |
markus@openbsd.org | f582f0e | 2015-01-19 20:30:23 +0000 | [diff] [blame] | 477 | return (k->key); |
| 478 | } |
| 479 | return (NULL); |
| 480 | } |
| 481 | |
| 482 | int |
| 483 | _ssh_verify_host_key(struct sshkey *hostkey, struct ssh *ssh) |
| 484 | { |
| 485 | struct key_entry *k; |
| 486 | |
| 487 | debug3("%s: need %s", __func__, sshkey_type(hostkey)); |
| 488 | TAILQ_FOREACH(k, &ssh->public_keys, next) { |
| 489 | debug3("%s: check %s", __func__, sshkey_type(k->key)); |
| 490 | if (sshkey_equal_public(hostkey, k->key)) |
| 491 | return (0); /* ok */ |
| 492 | } |
| 493 | return (-1); /* failed */ |
| 494 | } |
| 495 | |
| 496 | /* offer hostkey algorithms in kexinit depending on registered keys */ |
| 497 | int |
| 498 | _ssh_order_hostkeyalgs(struct ssh *ssh) |
| 499 | { |
| 500 | struct key_entry *k; |
| 501 | char *orig, *avail, *oavail = NULL, *alg, *replace = NULL; |
| 502 | char **proposal; |
| 503 | size_t maxlen; |
| 504 | int ktype, r; |
| 505 | |
| 506 | /* XXX we de-serialize ssh->kex->my, modify it, and change it */ |
| 507 | if ((r = kex_buf2prop(ssh->kex->my, NULL, &proposal)) != 0) |
| 508 | return r; |
| 509 | orig = proposal[PROPOSAL_SERVER_HOST_KEY_ALGS]; |
| 510 | if ((oavail = avail = strdup(orig)) == NULL) { |
| 511 | r = SSH_ERR_ALLOC_FAIL; |
| 512 | goto out; |
| 513 | } |
| 514 | maxlen = strlen(avail) + 1; |
| 515 | if ((replace = calloc(1, maxlen)) == NULL) { |
| 516 | r = SSH_ERR_ALLOC_FAIL; |
| 517 | goto out; |
| 518 | } |
| 519 | *replace = '\0'; |
| 520 | while ((alg = strsep(&avail, ",")) && *alg != '\0') { |
| 521 | if ((ktype = sshkey_type_from_name(alg)) == KEY_UNSPEC) |
| 522 | continue; |
| 523 | TAILQ_FOREACH(k, &ssh->public_keys, next) { |
| 524 | if (k->key->type == ktype || |
| 525 | (sshkey_is_cert(k->key) && k->key->type == |
| 526 | sshkey_type_plain(ktype))) { |
| 527 | if (*replace != '\0') |
| 528 | strlcat(replace, ",", maxlen); |
| 529 | strlcat(replace, alg, maxlen); |
| 530 | break; |
| 531 | } |
| 532 | } |
| 533 | } |
| 534 | if (*replace != '\0') { |
| 535 | debug2("%s: orig/%d %s", __func__, ssh->kex->server, orig); |
| 536 | debug2("%s: replace/%d %s", __func__, ssh->kex->server, replace); |
| 537 | free(orig); |
| 538 | proposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = replace; |
| 539 | replace = NULL; /* owned by proposal */ |
| 540 | r = kex_prop2buf(ssh->kex->my, proposal); |
| 541 | } |
| 542 | out: |
| 543 | free(oavail); |
| 544 | free(replace); |
| 545 | kex_prop_free(proposal); |
| 546 | return r; |
| 547 | } |
| 548 | |
| 549 | int |
djm@openbsd.org | 04c091f | 2019-01-19 21:43:56 +0000 | [diff] [blame] | 550 | _ssh_host_key_sign(struct ssh *ssh, struct sshkey *privkey, |
| 551 | struct sshkey *pubkey, u_char **signature, size_t *slen, |
| 552 | const u_char *data, size_t dlen, const char *alg) |
markus@openbsd.org | f582f0e | 2015-01-19 20:30:23 +0000 | [diff] [blame] | 553 | { |
djm@openbsd.org | 04c091f | 2019-01-19 21:43:56 +0000 | [diff] [blame] | 554 | return sshkey_sign(privkey, signature, slen, data, dlen, |
| 555 | alg, ssh->compat); |
markus@openbsd.org | f582f0e | 2015-01-19 20:30:23 +0000 | [diff] [blame] | 556 | } |