Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 1 | /* $OpenBSD: auth2-pubkey.c,v 1.47 2015/02/17 00:14:05 djm Exp $ */ |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 2 | /* |
| 3 | * Copyright (c) 2000 Markus Friedl. All rights reserved. |
| 4 | * |
| 5 | * Redistribution and use in source and binary forms, with or without |
| 6 | * modification, are permitted provided that the following conditions |
| 7 | * are met: |
| 8 | * 1. Redistributions of source code must retain the above copyright |
| 9 | * notice, this list of conditions and the following disclaimer. |
| 10 | * 2. Redistributions in binary form must reproduce the above copyright |
| 11 | * notice, this list of conditions and the following disclaimer in the |
| 12 | * documentation and/or other materials provided with the distribution. |
| 13 | * |
| 14 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR |
| 15 | * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
| 16 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. |
| 17 | * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, |
| 18 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT |
| 19 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
| 20 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
| 21 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| 22 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF |
| 23 | * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| 24 | */ |
| 25 | |
| 26 | #include "includes.h" |
| 27 | |
| 28 | #include <sys/types.h> |
| 29 | #include <sys/stat.h> |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 30 | #include <sys/wait.h> |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 31 | |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 32 | #include <errno.h> |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 33 | #include <fcntl.h> |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 34 | #ifdef HAVE_PATHS_H |
| 35 | # include <paths.h> |
| 36 | #endif |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 37 | #include <pwd.h> |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 38 | #include <signal.h> |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 39 | #include <stdio.h> |
| 40 | #include <stdarg.h> |
| 41 | #include <string.h> |
| 42 | #include <time.h> |
| 43 | #include <unistd.h> |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 44 | #include <limits.h> |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 45 | |
| 46 | #include "xmalloc.h" |
| 47 | #include "ssh.h" |
| 48 | #include "ssh2.h" |
| 49 | #include "packet.h" |
| 50 | #include "buffer.h" |
| 51 | #include "log.h" |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 52 | #include "misc.h" |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 53 | #include "servconf.h" |
| 54 | #include "compat.h" |
| 55 | #include "key.h" |
| 56 | #include "hostfile.h" |
| 57 | #include "auth.h" |
| 58 | #include "pathnames.h" |
| 59 | #include "uidswap.h" |
| 60 | #include "auth-options.h" |
| 61 | #include "canohost.h" |
| 62 | #ifdef GSSAPI |
| 63 | #include "ssh-gss.h" |
| 64 | #endif |
| 65 | #include "monitor_wrap.h" |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 66 | #include "authfile.h" |
| 67 | #include "match.h" |
| 68 | |
| 69 | /* import */ |
| 70 | extern ServerOptions options; |
| 71 | extern u_char *session_id2; |
| 72 | extern u_int session_id2_len; |
| 73 | |
| 74 | static int |
| 75 | userauth_pubkey(Authctxt *authctxt) |
| 76 | { |
| 77 | Buffer b; |
| 78 | Key *key = NULL; |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 79 | char *pkalg, *userstyle; |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 80 | u_char *pkblob, *sig; |
| 81 | u_int alen, blen, slen; |
| 82 | int have_sig, pktype; |
| 83 | int authenticated = 0; |
| 84 | |
| 85 | if (!authctxt->valid) { |
| 86 | debug2("userauth_pubkey: disabled because of invalid user"); |
| 87 | return 0; |
| 88 | } |
| 89 | have_sig = packet_get_char(); |
| 90 | if (datafellows & SSH_BUG_PKAUTH) { |
| 91 | debug2("userauth_pubkey: SSH_BUG_PKAUTH"); |
| 92 | /* no explicit pkalg given */ |
| 93 | pkblob = packet_get_string(&blen); |
| 94 | buffer_init(&b); |
| 95 | buffer_append(&b, pkblob, blen); |
| 96 | /* so we have to extract the pkalg from the pkblob */ |
| 97 | pkalg = buffer_get_string(&b, &alen); |
| 98 | buffer_free(&b); |
| 99 | } else { |
| 100 | pkalg = packet_get_string(&alen); |
| 101 | pkblob = packet_get_string(&blen); |
| 102 | } |
| 103 | pktype = key_type_from_name(pkalg); |
| 104 | if (pktype == KEY_UNSPEC) { |
| 105 | /* this is perfectly legal */ |
| 106 | logit("userauth_pubkey: unsupported public key algorithm: %s", |
| 107 | pkalg); |
| 108 | goto done; |
| 109 | } |
| 110 | key = key_from_blob(pkblob, blen); |
| 111 | if (key == NULL) { |
| 112 | error("userauth_pubkey: cannot decode key: %s", pkalg); |
| 113 | goto done; |
| 114 | } |
| 115 | if (key->type != pktype) { |
| 116 | error("userauth_pubkey: type mismatch for decoded key " |
| 117 | "(received %d, expected %d)", key->type, pktype); |
| 118 | goto done; |
| 119 | } |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 120 | if (key_type_plain(key->type) == KEY_RSA && |
| 121 | (datafellows & SSH_BUG_RSASIGMD5) != 0) { |
| 122 | logit("Refusing RSA key because client uses unsafe " |
| 123 | "signature scheme"); |
| 124 | goto done; |
| 125 | } |
| 126 | if (auth2_userkey_already_used(authctxt, key)) { |
| 127 | logit("refusing previously-used %s key", key_type(key)); |
| 128 | goto done; |
| 129 | } |
| 130 | if (match_pattern_list(sshkey_ssh_name(key), options.pubkey_key_types, |
| 131 | strlen(options.pubkey_key_types), 0) != 1) { |
| 132 | logit("%s: key type %s not in PubkeyAcceptedKeyTypes", |
| 133 | __func__, sshkey_ssh_name(key)); |
| 134 | goto done; |
| 135 | } |
| 136 | |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 137 | if (have_sig) { |
| 138 | sig = packet_get_string(&slen); |
| 139 | packet_check_eom(); |
| 140 | buffer_init(&b); |
| 141 | if (datafellows & SSH_OLD_SESSIONID) { |
| 142 | buffer_append(&b, session_id2, session_id2_len); |
| 143 | } else { |
| 144 | buffer_put_string(&b, session_id2, session_id2_len); |
| 145 | } |
| 146 | /* reconstruct packet */ |
| 147 | buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 148 | xasprintf(&userstyle, "%s%s%s", authctxt->user, |
| 149 | authctxt->style ? ":" : "", |
| 150 | authctxt->style ? authctxt->style : ""); |
| 151 | buffer_put_cstring(&b, userstyle); |
| 152 | free(userstyle); |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 153 | buffer_put_cstring(&b, |
| 154 | datafellows & SSH_BUG_PKSERVICE ? |
| 155 | "ssh-userauth" : |
| 156 | authctxt->service); |
| 157 | if (datafellows & SSH_BUG_PKAUTH) { |
| 158 | buffer_put_char(&b, have_sig); |
| 159 | } else { |
| 160 | buffer_put_cstring(&b, "publickey"); |
| 161 | buffer_put_char(&b, have_sig); |
| 162 | buffer_put_cstring(&b, pkalg); |
| 163 | } |
| 164 | buffer_put_string(&b, pkblob, blen); |
| 165 | #ifdef DEBUG_PK |
| 166 | buffer_dump(&b); |
| 167 | #endif |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 168 | pubkey_auth_info(authctxt, key, NULL); |
| 169 | |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 170 | /* test for correct signature */ |
| 171 | authenticated = 0; |
| 172 | if (PRIVSEP(user_key_allowed(authctxt->pw, key)) && |
| 173 | PRIVSEP(key_verify(key, sig, slen, buffer_ptr(&b), |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 174 | buffer_len(&b))) == 1) { |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 175 | authenticated = 1; |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 176 | /* Record the successful key to prevent reuse */ |
| 177 | auth2_record_userkey(authctxt, key); |
| 178 | key = NULL; /* Don't free below */ |
| 179 | } |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 180 | buffer_free(&b); |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 181 | free(sig); |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 182 | } else { |
| 183 | debug("test whether pkalg/pkblob are acceptable"); |
| 184 | packet_check_eom(); |
| 185 | |
| 186 | /* XXX fake reply and always send PK_OK ? */ |
| 187 | /* |
| 188 | * XXX this allows testing whether a user is allowed |
| 189 | * to login: if you happen to have a valid pubkey this |
| 190 | * message is sent. the message is NEVER sent at all |
| 191 | * if a user is not allowed to login. is this an |
| 192 | * issue? -markus |
| 193 | */ |
| 194 | if (PRIVSEP(user_key_allowed(authctxt->pw, key))) { |
| 195 | packet_start(SSH2_MSG_USERAUTH_PK_OK); |
| 196 | packet_put_string(pkalg, alen); |
| 197 | packet_put_string(pkblob, blen); |
| 198 | packet_send(); |
| 199 | packet_write_wait(); |
| 200 | authctxt->postponed = 1; |
| 201 | } |
| 202 | } |
| 203 | if (authenticated != 1) |
| 204 | auth_clear_options(); |
| 205 | done: |
| 206 | debug2("userauth_pubkey: authenticated %d pkalg %s", authenticated, pkalg); |
| 207 | if (key != NULL) |
| 208 | key_free(key); |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 209 | free(pkalg); |
| 210 | free(pkblob); |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 211 | return authenticated; |
| 212 | } |
| 213 | |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 214 | void |
| 215 | pubkey_auth_info(Authctxt *authctxt, const Key *key, const char *fmt, ...) |
| 216 | { |
| 217 | char *fp, *extra; |
| 218 | va_list ap; |
| 219 | int i; |
| 220 | |
| 221 | extra = NULL; |
| 222 | if (fmt != NULL) { |
| 223 | va_start(ap, fmt); |
| 224 | i = vasprintf(&extra, fmt, ap); |
| 225 | va_end(ap); |
| 226 | if (i < 0 || extra == NULL) |
| 227 | fatal("%s: vasprintf failed", __func__); |
| 228 | } |
| 229 | |
| 230 | if (key_is_cert(key)) { |
| 231 | fp = sshkey_fingerprint(key->cert->signature_key, |
| 232 | options.fingerprint_hash, SSH_FP_DEFAULT); |
| 233 | auth_info(authctxt, "%s ID %s (serial %llu) CA %s %s%s%s", |
| 234 | key_type(key), key->cert->key_id, |
| 235 | (unsigned long long)key->cert->serial, |
| 236 | key_type(key->cert->signature_key), |
| 237 | fp == NULL ? "(null)" : fp, |
| 238 | extra == NULL ? "" : ", ", extra == NULL ? "" : extra); |
| 239 | free(fp); |
| 240 | } else { |
| 241 | fp = sshkey_fingerprint(key, options.fingerprint_hash, |
| 242 | SSH_FP_DEFAULT); |
| 243 | auth_info(authctxt, "%s %s%s%s", key_type(key), |
| 244 | fp == NULL ? "(null)" : fp, |
| 245 | extra == NULL ? "" : ", ", extra == NULL ? "" : extra); |
| 246 | free(fp); |
| 247 | } |
| 248 | free(extra); |
| 249 | } |
| 250 | |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 251 | static int |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 252 | match_principals_option(const char *principal_list, struct sshkey_cert *cert) |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 253 | { |
| 254 | char *result; |
| 255 | u_int i; |
| 256 | |
| 257 | /* XXX percent_expand() sequences for authorized_principals? */ |
| 258 | |
| 259 | for (i = 0; i < cert->nprincipals; i++) { |
| 260 | if ((result = match_list(cert->principals[i], |
| 261 | principal_list, NULL)) != NULL) { |
| 262 | debug3("matched principal from key options \"%.100s\"", |
| 263 | result); |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 264 | free(result); |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 265 | return 1; |
| 266 | } |
| 267 | } |
| 268 | return 0; |
| 269 | } |
| 270 | |
| 271 | static int |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 272 | match_principals_file(char *file, struct passwd *pw, struct sshkey_cert *cert) |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 273 | { |
| 274 | FILE *f; |
| 275 | char line[SSH_MAX_PUBKEY_BYTES], *cp, *ep, *line_opts; |
| 276 | u_long linenum = 0; |
| 277 | u_int i; |
| 278 | |
| 279 | temporarily_use_uid(pw); |
| 280 | debug("trying authorized principals file %s", file); |
| 281 | if ((f = auth_openprincipals(file, pw, options.strict_modes)) == NULL) { |
| 282 | restore_uid(); |
| 283 | return 0; |
| 284 | } |
| 285 | while (read_keyfile_line(f, file, line, sizeof(line), &linenum) != -1) { |
| 286 | /* Skip leading whitespace. */ |
| 287 | for (cp = line; *cp == ' ' || *cp == '\t'; cp++) |
| 288 | ; |
| 289 | /* Skip blank and comment lines. */ |
| 290 | if ((ep = strchr(cp, '#')) != NULL) |
| 291 | *ep = '\0'; |
| 292 | if (!*cp || *cp == '\n') |
| 293 | continue; |
| 294 | /* Trim trailing whitespace. */ |
| 295 | ep = cp + strlen(cp) - 1; |
| 296 | while (ep > cp && (*ep == '\n' || *ep == ' ' || *ep == '\t')) |
| 297 | *ep-- = '\0'; |
| 298 | /* |
| 299 | * If the line has internal whitespace then assume it has |
| 300 | * key options. |
| 301 | */ |
| 302 | line_opts = NULL; |
| 303 | if ((ep = strrchr(cp, ' ')) != NULL || |
| 304 | (ep = strrchr(cp, '\t')) != NULL) { |
| 305 | for (; *ep == ' ' || *ep == '\t'; ep++) |
| 306 | ; |
| 307 | line_opts = cp; |
| 308 | cp = ep; |
| 309 | } |
| 310 | for (i = 0; i < cert->nprincipals; i++) { |
| 311 | if (strcmp(cp, cert->principals[i]) == 0) { |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 312 | debug3("matched principal \"%.100s\" " |
| 313 | "from file \"%s\" on line %lu", |
| 314 | cert->principals[i], file, linenum); |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 315 | if (auth_parse_options(pw, line_opts, |
| 316 | file, linenum) != 1) |
| 317 | continue; |
| 318 | fclose(f); |
| 319 | restore_uid(); |
| 320 | return 1; |
| 321 | } |
| 322 | } |
| 323 | } |
| 324 | fclose(f); |
| 325 | restore_uid(); |
| 326 | return 0; |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 327 | } |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 328 | |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 329 | /* |
| 330 | * Checks whether key is allowed in authorized_keys-format file, |
| 331 | * returns 1 if the key is allowed or 0 otherwise. |
| 332 | */ |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 333 | static int |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 334 | check_authkeys_file(FILE *f, char *file, Key* key, struct passwd *pw) |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 335 | { |
| 336 | char line[SSH_MAX_PUBKEY_BYTES]; |
| 337 | const char *reason; |
| 338 | int found_key = 0; |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 339 | u_long linenum = 0; |
| 340 | Key *found; |
| 341 | char *fp; |
| 342 | |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 343 | found_key = 0; |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 344 | |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 345 | found = NULL; |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 346 | while (read_keyfile_line(f, file, line, sizeof(line), &linenum) != -1) { |
| 347 | char *cp, *key_options = NULL; |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 348 | if (found != NULL) |
| 349 | key_free(found); |
| 350 | found = key_new(key_is_cert(key) ? KEY_UNSPEC : key->type); |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 351 | auth_clear_options(); |
| 352 | |
| 353 | /* Skip leading whitespace, empty and comment lines. */ |
| 354 | for (cp = line; *cp == ' ' || *cp == '\t'; cp++) |
| 355 | ; |
| 356 | if (!*cp || *cp == '\n' || *cp == '#') |
| 357 | continue; |
| 358 | |
| 359 | if (key_read(found, &cp) != 1) { |
| 360 | /* no key? check if there are options for this key */ |
| 361 | int quoted = 0; |
| 362 | debug2("user_key_allowed: check options: '%s'", cp); |
| 363 | key_options = cp; |
| 364 | for (; *cp && (quoted || (*cp != ' ' && *cp != '\t')); cp++) { |
| 365 | if (*cp == '\\' && cp[1] == '"') |
| 366 | cp++; /* Skip both */ |
| 367 | else if (*cp == '"') |
| 368 | quoted = !quoted; |
| 369 | } |
| 370 | /* Skip remaining whitespace. */ |
| 371 | for (; *cp == ' ' || *cp == '\t'; cp++) |
| 372 | ; |
| 373 | if (key_read(found, &cp) != 1) { |
| 374 | debug2("user_key_allowed: advance: '%s'", cp); |
| 375 | /* still no key? advance to next line*/ |
| 376 | continue; |
| 377 | } |
| 378 | } |
| 379 | if (key_is_cert(key)) { |
| 380 | if (!key_equal(found, key->cert->signature_key)) |
| 381 | continue; |
| 382 | if (auth_parse_options(pw, key_options, file, |
| 383 | linenum) != 1) |
| 384 | continue; |
| 385 | if (!key_is_cert_authority) |
| 386 | continue; |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 387 | if ((fp = sshkey_fingerprint(found, |
| 388 | options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) |
| 389 | continue; |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 390 | debug("matching CA found: file %s, line %lu, %s %s", |
| 391 | file, linenum, key_type(found), fp); |
| 392 | /* |
| 393 | * If the user has specified a list of principals as |
| 394 | * a key option, then prefer that list to matching |
| 395 | * their username in the certificate principals list. |
| 396 | */ |
| 397 | if (authorized_principals != NULL && |
| 398 | !match_principals_option(authorized_principals, |
| 399 | key->cert)) { |
| 400 | reason = "Certificate does not contain an " |
| 401 | "authorized principal"; |
| 402 | fail_reason: |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 403 | free(fp); |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 404 | error("%s", reason); |
| 405 | auth_debug_add("%s", reason); |
| 406 | continue; |
| 407 | } |
| 408 | if (key_cert_check_authority(key, 0, 0, |
| 409 | authorized_principals == NULL ? pw->pw_name : NULL, |
| 410 | &reason) != 0) |
| 411 | goto fail_reason; |
| 412 | if (auth_cert_options(key, pw) != 0) { |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 413 | free(fp); |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 414 | continue; |
| 415 | } |
| 416 | verbose("Accepted certificate ID \"%s\" " |
| 417 | "signed by %s CA %s via %s", key->cert->key_id, |
| 418 | key_type(found), fp, file); |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 419 | free(fp); |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 420 | found_key = 1; |
| 421 | break; |
| 422 | } else if (key_equal(found, key)) { |
| 423 | if (auth_parse_options(pw, key_options, file, |
| 424 | linenum) != 1) |
| 425 | continue; |
| 426 | if (key_is_cert_authority) |
| 427 | continue; |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 428 | if ((fp = sshkey_fingerprint(found, |
| 429 | options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) |
| 430 | continue; |
| 431 | debug("matching key found: file %s, line %lu %s %s", |
| 432 | file, linenum, key_type(found), fp); |
| 433 | free(fp); |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 434 | found_key = 1; |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 435 | break; |
| 436 | } |
| 437 | } |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 438 | if (found != NULL) |
| 439 | key_free(found); |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 440 | if (!found_key) |
| 441 | debug2("key not found"); |
| 442 | return found_key; |
| 443 | } |
| 444 | |
| 445 | /* Authenticate a certificate key against TrustedUserCAKeys */ |
| 446 | static int |
| 447 | user_cert_trusted_ca(struct passwd *pw, Key *key) |
| 448 | { |
| 449 | char *ca_fp, *principals_file = NULL; |
| 450 | const char *reason; |
| 451 | int ret = 0; |
| 452 | |
| 453 | if (!key_is_cert(key) || options.trusted_user_ca_keys == NULL) |
| 454 | return 0; |
| 455 | |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 456 | if ((ca_fp = sshkey_fingerprint(key->cert->signature_key, |
| 457 | options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) |
| 458 | return 0; |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 459 | |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 460 | if (sshkey_in_file(key->cert->signature_key, |
| 461 | options.trusted_user_ca_keys, 1, 0) != 0) { |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 462 | debug2("%s: CA %s %s is not listed in %s", __func__, |
| 463 | key_type(key->cert->signature_key), ca_fp, |
| 464 | options.trusted_user_ca_keys); |
| 465 | goto out; |
| 466 | } |
| 467 | /* |
| 468 | * If AuthorizedPrincipals is in use, then compare the certificate |
| 469 | * principals against the names in that file rather than matching |
| 470 | * against the username. |
| 471 | */ |
| 472 | if ((principals_file = authorized_principals_file(pw)) != NULL) { |
| 473 | if (!match_principals_file(principals_file, pw, key->cert)) { |
| 474 | reason = "Certificate does not contain an " |
| 475 | "authorized principal"; |
| 476 | fail_reason: |
| 477 | error("%s", reason); |
| 478 | auth_debug_add("%s", reason); |
| 479 | goto out; |
| 480 | } |
| 481 | } |
| 482 | if (key_cert_check_authority(key, 0, 1, |
| 483 | principals_file == NULL ? pw->pw_name : NULL, &reason) != 0) |
| 484 | goto fail_reason; |
| 485 | if (auth_cert_options(key, pw) != 0) |
| 486 | goto out; |
| 487 | |
| 488 | verbose("Accepted certificate ID \"%s\" signed by %s CA %s via %s", |
| 489 | key->cert->key_id, key_type(key->cert->signature_key), ca_fp, |
| 490 | options.trusted_user_ca_keys); |
| 491 | ret = 1; |
| 492 | |
| 493 | out: |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 494 | free(principals_file); |
| 495 | free(ca_fp); |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 496 | return ret; |
| 497 | } |
| 498 | |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 499 | /* |
| 500 | * Checks whether key is allowed in file. |
| 501 | * returns 1 if the key is allowed or 0 otherwise. |
| 502 | */ |
| 503 | static int |
| 504 | user_key_allowed2(struct passwd *pw, Key *key, char *file) |
| 505 | { |
| 506 | FILE *f; |
| 507 | int found_key = 0; |
| 508 | |
| 509 | /* Temporarily use the user's uid. */ |
| 510 | temporarily_use_uid(pw); |
| 511 | |
| 512 | debug("trying public key file %s", file); |
| 513 | if ((f = auth_openkeyfile(file, pw, options.strict_modes)) != NULL) { |
| 514 | found_key = check_authkeys_file(f, file, key, pw); |
| 515 | fclose(f); |
| 516 | } |
| 517 | |
| 518 | restore_uid(); |
| 519 | return found_key; |
| 520 | } |
| 521 | |
| 522 | /* |
| 523 | * Checks whether key is allowed in output of command. |
| 524 | * returns 1 if the key is allowed or 0 otherwise. |
| 525 | */ |
| 526 | static int |
| 527 | user_key_command_allowed2(struct passwd *user_pw, Key *key) |
| 528 | { |
| 529 | FILE *f; |
| 530 | int ok, found_key = 0; |
| 531 | struct passwd *pw; |
| 532 | struct stat st; |
| 533 | int status, devnull, p[2], i; |
| 534 | pid_t pid; |
| 535 | char *username, errmsg[512]; |
| 536 | |
| 537 | if (options.authorized_keys_command == NULL || |
| 538 | options.authorized_keys_command[0] != '/') |
| 539 | return 0; |
| 540 | |
| 541 | if (options.authorized_keys_command_user == NULL) { |
| 542 | error("No user for AuthorizedKeysCommand specified, skipping"); |
| 543 | return 0; |
| 544 | } |
| 545 | |
| 546 | username = percent_expand(options.authorized_keys_command_user, |
| 547 | "u", user_pw->pw_name, (char *)NULL); |
| 548 | pw = getpwnam(username); |
| 549 | if (pw == NULL) { |
| 550 | error("AuthorizedKeysCommandUser \"%s\" not found: %s", |
| 551 | username, strerror(errno)); |
| 552 | free(username); |
| 553 | return 0; |
| 554 | } |
| 555 | free(username); |
| 556 | |
| 557 | temporarily_use_uid(pw); |
| 558 | |
| 559 | if (stat(options.authorized_keys_command, &st) < 0) { |
| 560 | error("Could not stat AuthorizedKeysCommand \"%s\": %s", |
| 561 | options.authorized_keys_command, strerror(errno)); |
| 562 | goto out; |
| 563 | } |
| 564 | if (auth_secure_path(options.authorized_keys_command, &st, NULL, 0, |
| 565 | errmsg, sizeof(errmsg)) != 0) { |
| 566 | error("Unsafe AuthorizedKeysCommand: %s", errmsg); |
| 567 | goto out; |
| 568 | } |
| 569 | |
| 570 | if (pipe(p) != 0) { |
| 571 | error("%s: pipe: %s", __func__, strerror(errno)); |
| 572 | goto out; |
| 573 | } |
| 574 | |
| 575 | debug3("Running AuthorizedKeysCommand: \"%s %s\" as \"%s\"", |
| 576 | options.authorized_keys_command, user_pw->pw_name, pw->pw_name); |
| 577 | |
| 578 | /* |
| 579 | * Don't want to call this in the child, where it can fatal() and |
| 580 | * run cleanup_exit() code. |
| 581 | */ |
| 582 | restore_uid(); |
| 583 | |
| 584 | switch ((pid = fork())) { |
| 585 | case -1: /* error */ |
| 586 | error("%s: fork: %s", __func__, strerror(errno)); |
| 587 | close(p[0]); |
| 588 | close(p[1]); |
| 589 | return 0; |
| 590 | case 0: /* child */ |
| 591 | for (i = 0; i < NSIG; i++) |
| 592 | signal(i, SIG_DFL); |
| 593 | |
| 594 | if ((devnull = open(_PATH_DEVNULL, O_RDWR)) == -1) { |
| 595 | error("%s: open %s: %s", __func__, _PATH_DEVNULL, |
| 596 | strerror(errno)); |
| 597 | _exit(1); |
| 598 | } |
| 599 | /* Keep stderr around a while longer to catch errors */ |
| 600 | if (dup2(devnull, STDIN_FILENO) == -1 || |
| 601 | dup2(p[1], STDOUT_FILENO) == -1) { |
| 602 | error("%s: dup2: %s", __func__, strerror(errno)); |
| 603 | _exit(1); |
| 604 | } |
| 605 | closefrom(STDERR_FILENO + 1); |
| 606 | |
| 607 | /* Don't use permanently_set_uid() here to avoid fatal() */ |
| 608 | if (setresgid(pw->pw_gid, pw->pw_gid, pw->pw_gid) != 0) { |
| 609 | error("setresgid %u: %s", (u_int)pw->pw_gid, |
| 610 | strerror(errno)); |
| 611 | _exit(1); |
| 612 | } |
| 613 | if (setresuid(pw->pw_uid, pw->pw_uid, pw->pw_uid) != 0) { |
| 614 | error("setresuid %u: %s", (u_int)pw->pw_uid, |
| 615 | strerror(errno)); |
| 616 | _exit(1); |
| 617 | } |
| 618 | /* stdin is pointed to /dev/null at this point */ |
| 619 | if (dup2(STDIN_FILENO, STDERR_FILENO) == -1) { |
| 620 | error("%s: dup2: %s", __func__, strerror(errno)); |
| 621 | _exit(1); |
| 622 | } |
| 623 | |
| 624 | execl(options.authorized_keys_command, |
| 625 | options.authorized_keys_command, user_pw->pw_name, NULL); |
| 626 | |
| 627 | error("AuthorizedKeysCommand %s exec failed: %s", |
| 628 | options.authorized_keys_command, strerror(errno)); |
| 629 | _exit(127); |
| 630 | default: /* parent */ |
| 631 | break; |
| 632 | } |
| 633 | |
| 634 | temporarily_use_uid(pw); |
| 635 | |
| 636 | close(p[1]); |
| 637 | if ((f = fdopen(p[0], "r")) == NULL) { |
| 638 | error("%s: fdopen: %s", __func__, strerror(errno)); |
| 639 | close(p[0]); |
| 640 | /* Don't leave zombie child */ |
| 641 | kill(pid, SIGTERM); |
| 642 | while (waitpid(pid, NULL, 0) == -1 && errno == EINTR) |
| 643 | ; |
| 644 | goto out; |
| 645 | } |
| 646 | ok = check_authkeys_file(f, options.authorized_keys_command, key, pw); |
| 647 | fclose(f); |
| 648 | |
| 649 | while (waitpid(pid, &status, 0) == -1) { |
| 650 | if (errno != EINTR) { |
| 651 | error("%s: waitpid: %s", __func__, strerror(errno)); |
| 652 | goto out; |
| 653 | } |
| 654 | } |
| 655 | if (WIFSIGNALED(status)) { |
| 656 | error("AuthorizedKeysCommand %s exited on signal %d", |
| 657 | options.authorized_keys_command, WTERMSIG(status)); |
| 658 | goto out; |
| 659 | } else if (WEXITSTATUS(status) != 0) { |
| 660 | error("AuthorizedKeysCommand %s returned status %d", |
| 661 | options.authorized_keys_command, WEXITSTATUS(status)); |
| 662 | goto out; |
| 663 | } |
| 664 | found_key = ok; |
| 665 | out: |
| 666 | restore_uid(); |
| 667 | return found_key; |
| 668 | } |
| 669 | |
| 670 | /* |
| 671 | * Check whether key authenticates and authorises the user. |
| 672 | */ |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 673 | int |
| 674 | user_key_allowed(struct passwd *pw, Key *key) |
| 675 | { |
| 676 | u_int success, i; |
| 677 | char *file; |
| 678 | |
| 679 | if (auth_key_is_revoked(key)) |
| 680 | return 0; |
| 681 | if (key_is_cert(key) && auth_key_is_revoked(key->cert->signature_key)) |
| 682 | return 0; |
| 683 | |
| 684 | success = user_cert_trusted_ca(pw, key); |
| 685 | if (success) |
| 686 | return success; |
| 687 | |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 688 | success = user_key_command_allowed2(pw, key); |
| 689 | if (success > 0) |
| 690 | return success; |
| 691 | |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 692 | for (i = 0; !success && i < options.num_authkeys_files; i++) { |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 693 | |
| 694 | if (strcasecmp(options.authorized_keys_files[i], "none") == 0) |
| 695 | continue; |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 696 | file = expand_authorized_keys( |
| 697 | options.authorized_keys_files[i], pw); |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 698 | |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 699 | success = user_key_allowed2(pw, key, file); |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 700 | free(file); |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 701 | } |
| 702 | |
| 703 | return success; |
| 704 | } |
| 705 | |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 706 | /* Records a public key in the list of previously-successful keys */ |
| 707 | void |
| 708 | auth2_record_userkey(Authctxt *authctxt, struct sshkey *key) |
| 709 | { |
| 710 | struct sshkey **tmp; |
| 711 | |
| 712 | if (authctxt->nprev_userkeys >= INT_MAX || |
| 713 | (tmp = reallocarray(authctxt->prev_userkeys, |
| 714 | authctxt->nprev_userkeys + 1, sizeof(*tmp))) == NULL) |
| 715 | fatal("%s: reallocarray failed", __func__); |
| 716 | authctxt->prev_userkeys = tmp; |
| 717 | authctxt->prev_userkeys[authctxt->nprev_userkeys] = key; |
| 718 | authctxt->nprev_userkeys++; |
| 719 | } |
| 720 | |
| 721 | /* Checks whether a key has already been used successfully for authentication */ |
| 722 | int |
| 723 | auth2_userkey_already_used(Authctxt *authctxt, struct sshkey *key) |
| 724 | { |
| 725 | u_int i; |
| 726 | |
| 727 | for (i = 0; i < authctxt->nprev_userkeys; i++) { |
| 728 | if (sshkey_equal_public(key, authctxt->prev_userkeys[i])) { |
| 729 | return 1; |
| 730 | } |
| 731 | } |
| 732 | return 0; |
| 733 | } |
| 734 | |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 735 | Authmethod method_pubkey = { |
| 736 | "publickey", |
| 737 | userauth_pubkey, |
| 738 | &options.pubkey_authentication |
| 739 | }; |