Annotation of src/usr.bin/ssh/auth2-pubkey.c, Revision 1.119
1.119 ! djm 1: /* $OpenBSD: auth2-pubkey.c,v 1.118 2023/02/17 04:22:50 dtucker Exp $ */
1.1 markus 2: /*
3: * Copyright (c) 2000 Markus Friedl. All rights reserved.
1.115 djm 4: * Copyright (c) 2010 Damien Miller. All rights reserved.
1.1 markus 5: *
6: * Redistribution and use in source and binary forms, with or without
7: * modification, are permitted provided that the following conditions
8: * are met:
9: * 1. Redistributions of source code must retain the above copyright
10: * notice, this list of conditions and the following disclaimer.
11: * 2. Redistributions in binary form must reproduce the above copyright
12: * notice, this list of conditions and the following disclaimer in the
13: * documentation and/or other materials provided with the distribution.
14: *
15: * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
16: * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
17: * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
18: * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
19: * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
20: * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
21: * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
22: * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
23: * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
24: * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25: */
26:
1.10 stevesk 27:
28: #include <sys/types.h>
1.13 stevesk 29:
1.94 djm 30: #include <stdlib.h>
1.31 djm 31: #include <errno.h>
32: #include <paths.h>
1.13 stevesk 33: #include <pwd.h>
1.31 djm 34: #include <signal.h>
1.14 stevesk 35: #include <stdio.h>
1.15 deraadt 36: #include <stdarg.h>
1.20 djm 37: #include <string.h>
38: #include <time.h>
1.17 dtucker 39: #include <unistd.h>
1.44 djm 40: #include <limits.h>
1.1 markus 41:
1.15 deraadt 42: #include "xmalloc.h"
1.8 dtucker 43: #include "ssh.h"
1.1 markus 44: #include "ssh2.h"
45: #include "packet.h"
1.106 djm 46: #include "kex.h"
1.81 markus 47: #include "sshbuf.h"
1.1 markus 48: #include "log.h"
1.41 millert 49: #include "misc.h"
1.1 markus 50: #include "servconf.h"
51: #include "compat.h"
1.64 markus 52: #include "sshkey.h"
1.15 deraadt 53: #include "hostfile.h"
1.1 markus 54: #include "auth.h"
55: #include "pathnames.h"
56: #include "uidswap.h"
57: #include "auth-options.h"
58: #include "canohost.h"
1.15 deraadt 59: #ifdef GSSAPI
60: #include "ssh-gss.h"
61: #endif
1.1 markus 62: #include "monitor_wrap.h"
1.21 djm 63: #include "authfile.h"
1.24 djm 64: #include "match.h"
1.50 djm 65: #include "ssherr.h"
66: #include "channels.h" /* XXX for session.h */
67: #include "session.h" /* XXX for child_set_env(); refactor? */
1.96 djm 68: #include "sk-api.h"
1.1 markus 69:
70: /* import */
71: extern ServerOptions options;
72:
1.73 djm 73: static char *
74: format_key(const struct sshkey *key)
75: {
76: char *ret, *fp = sshkey_fingerprint(key,
77: options.fingerprint_hash, SSH_FP_DEFAULT);
78:
79: xasprintf(&ret, "%s %s", sshkey_type(key), fp);
80: free(fp);
81: return ret;
82: }
83:
1.2 markus 84: static int
1.111 djm 85: userauth_pubkey(struct ssh *ssh, const char *method)
1.1 markus 86: {
1.65 markus 87: Authctxt *authctxt = ssh->authctxt;
1.77 djm 88: struct passwd *pw = authctxt->pw;
1.83 djm 89: struct sshbuf *b = NULL;
1.112 djm 90: struct sshkey *key = NULL, *hostkey = NULL;
1.83 djm 91: char *pkalg = NULL, *userstyle = NULL, *key_s = NULL, *ca_s = NULL;
92: u_char *pkblob = NULL, *sig = NULL, have_sig;
1.64 markus 93: size_t blen, slen;
1.112 djm 94: int hostbound, r, pktype;
1.100 djm 95: int req_presence = 0, req_verify = 0, authenticated = 0;
1.77 djm 96: struct sshauthopt *authopts = NULL;
1.95 djm 97: struct sshkey_sig_details *sig_details = NULL;
1.1 markus 98:
1.112 djm 99: hostbound = strcmp(method, "publickey-hostbound-v00@openssh.com") == 0;
100:
1.75 djm 101: if ((r = sshpkt_get_u8(ssh, &have_sig)) != 0 ||
102: (r = sshpkt_get_cstring(ssh, &pkalg, NULL)) != 0 ||
103: (r = sshpkt_get_string(ssh, &pkblob, &blen)) != 0)
1.112 djm 104: fatal_fr(r, "parse %s packet", method);
105:
106: /* hostbound auth includes the hostkey offered at initial KEX */
107: if (hostbound) {
108: if ((r = sshpkt_getb_froms(ssh, &b)) != 0 ||
109: (r = sshkey_fromb(b, &hostkey)) != 0)
110: fatal_fr(r, "parse %s hostkey", method);
111: if (ssh->kex->initial_hostkey == NULL)
112: fatal_f("internal error: initial hostkey not recorded");
113: if (!sshkey_equal(hostkey, ssh->kex->initial_hostkey))
114: fatal_f("%s packet contained wrong host key", method);
115: sshbuf_free(b);
116: b = NULL;
117: }
1.87 djm 118:
119: if (log_level_get() >= SYSLOG_LEVEL_DEBUG2) {
120: char *keystring;
121: struct sshbuf *pkbuf;
122:
123: if ((pkbuf = sshbuf_from(pkblob, blen)) == NULL)
1.101 djm 124: fatal_f("sshbuf_from failed");
1.91 djm 125: if ((keystring = sshbuf_dtob64_string(pkbuf, 0)) == NULL)
1.101 djm 126: fatal_f("sshbuf_dtob64 failed");
127: debug2_f("%s user %s %s public key %s %s",
1.87 djm 128: authctxt->valid ? "valid" : "invalid", authctxt->user,
129: have_sig ? "attempting" : "querying", pkalg, keystring);
130: sshbuf_free(pkbuf);
131: free(keystring);
132: }
133:
1.64 markus 134: pktype = sshkey_type_from_name(pkalg);
1.1 markus 135: if (pktype == KEY_UNSPEC) {
136: /* this is perfectly legal */
1.101 djm 137: verbose_f("unsupported public key algorithm: %s", pkalg);
1.1 markus 138: goto done;
139: }
1.64 markus 140: if ((r = sshkey_from_blob(pkblob, blen, &key)) != 0) {
1.101 djm 141: error_fr(r, "parse key");
1.64 markus 142: goto done;
143: }
1.1 markus 144: if (key == NULL) {
1.101 djm 145: error_f("cannot decode key: %s", pkalg);
1.1 markus 146: goto done;
147: }
148: if (key->type != pktype) {
1.101 djm 149: error_f("type mismatch for decoded key "
150: "(received %d, expected %d)", key->type, pktype);
1.1 markus 151: goto done;
152: }
1.68 djm 153: if (auth2_key_already_used(authctxt, key)) {
1.64 markus 154: logit("refusing previously-used %s key", sshkey_type(key));
1.44 djm 155: goto done;
156: }
1.104 dtucker 157: if (match_pattern_list(pkalg, options.pubkey_accepted_algos, 0) != 1) {
1.113 naddy 158: logit_f("signature algorithm %s not in "
159: "PubkeyAcceptedAlgorithms", pkalg);
1.45 djm 160: goto done;
161: }
1.86 djm 162: if ((r = sshkey_check_cert_sigtype(key,
163: options.ca_sign_algorithms)) != 0) {
1.101 djm 164: logit_fr(r, "certificate signature algorithm %s",
1.86 djm 165: (key->cert == NULL || key->cert->signature_type == NULL) ?
1.101 djm 166: "(null)" : key->cert->signature_type);
1.117 djm 167: goto done;
168: }
169: if ((r = sshkey_check_rsa_length(key,
170: options.required_rsa_size)) != 0) {
171: logit_r(r, "refusing %s key", sshkey_type(key));
1.86 djm 172: goto done;
173: }
1.73 djm 174: key_s = format_key(key);
175: if (sshkey_is_cert(key))
176: ca_s = format_key(key->cert->signature_key);
177:
1.1 markus 178: if (have_sig) {
1.112 djm 179: debug3_f("%s have %s signature for %s%s%s",
180: method, pkalg, key_s,
1.101 djm 181: ca_s == NULL ? "" : " CA ", ca_s == NULL ? "" : ca_s);
1.64 markus 182: if ((r = sshpkt_get_string(ssh, &sig, &slen)) != 0 ||
183: (r = sshpkt_get_end(ssh)) != 0)
1.101 djm 184: fatal_fr(r, "parse signature packet");
1.64 markus 185: if ((b = sshbuf_new()) == NULL)
1.101 djm 186: fatal_f("sshbuf_new failed");
1.64 markus 187: if (ssh->compat & SSH_OLD_SESSIONID) {
1.106 djm 188: if ((r = sshbuf_putb(b, ssh->kex->session_id)) != 0)
1.101 djm 189: fatal_fr(r, "put old session id");
1.1 markus 190: } else {
1.106 djm 191: if ((r = sshbuf_put_stringb(b,
192: ssh->kex->session_id)) != 0)
1.101 djm 193: fatal_fr(r, "put session id");
1.1 markus 194: }
1.83 djm 195: if (!authctxt->valid || authctxt->user == NULL) {
1.101 djm 196: debug2_f("disabled because of invalid user");
1.83 djm 197: goto done;
198: }
1.1 markus 199: /* reconstruct packet */
1.35 djm 200: xasprintf(&userstyle, "%s%s%s", authctxt->user,
201: authctxt->style ? ":" : "",
202: authctxt->style ? authctxt->style : "");
1.64 markus 203: if ((r = sshbuf_put_u8(b, SSH2_MSG_USERAUTH_REQUEST)) != 0 ||
204: (r = sshbuf_put_cstring(b, userstyle)) != 0 ||
1.75 djm 205: (r = sshbuf_put_cstring(b, authctxt->service)) != 0 ||
1.111 djm 206: (r = sshbuf_put_cstring(b, method)) != 0 ||
1.75 djm 207: (r = sshbuf_put_u8(b, have_sig)) != 0 ||
1.85 mestre 208: (r = sshbuf_put_cstring(b, pkalg)) != 0 ||
1.75 djm 209: (r = sshbuf_put_string(b, pkblob, blen)) != 0)
1.112 djm 210: fatal_fr(r, "reconstruct %s packet", method);
211: if (hostbound &&
212: (r = sshkey_puts(ssh->kex->initial_hostkey, b)) != 0)
213: fatal_fr(r, "reconstruct %s packet", method);
1.1 markus 214: #ifdef DEBUG_PK
1.64 markus 215: sshbuf_dump(b, stderr);
1.1 markus 216: #endif
217: /* test for correct signature */
218: authenticated = 0;
1.116 djm 219: if (PRIVSEP(user_key_allowed(ssh, pw, key, 1, &authopts)) &&
1.80 djm 220: PRIVSEP(sshkey_verify(key, sig, slen,
221: sshbuf_ptr(b), sshbuf_len(b),
222: (ssh->compat & SSH_BUG_SIGTYPE) == 0 ? pkalg : NULL,
1.95 djm 223: ssh->compat, &sig_details)) == 0) {
1.1 markus 224: authenticated = 1;
1.44 djm 225: }
1.96 djm 226: if (authenticated == 1 && sig_details != NULL) {
227: auth2_record_info(authctxt, "signature count = %u",
228: sig_details->sk_counter);
1.101 djm 229: debug_f("sk_counter = %u, sk_flags = 0x%02x",
230: sig_details->sk_counter, sig_details->sk_flags);
1.96 djm 231: req_presence = (options.pubkey_auth_options &
1.97 djm 232: PUBKEYAUTH_TOUCH_REQUIRED) ||
233: !authopts->no_require_user_presence;
1.96 djm 234: if (req_presence && (sig_details->sk_flags &
235: SSH_SK_USER_PRESENCE_REQD) == 0) {
236: error("public key %s signature for %s%s from "
237: "%.128s port %d rejected: user presence "
1.99 naddy 238: "(authenticator touch) requirement "
239: "not met ", key_s,
1.100 djm 240: authctxt->valid ? "" : "invalid user ",
241: authctxt->user, ssh_remote_ipaddr(ssh),
242: ssh_remote_port(ssh));
243: authenticated = 0;
244: goto done;
245: }
246: req_verify = (options.pubkey_auth_options &
247: PUBKEYAUTH_VERIFY_REQUIRED) ||
248: authopts->require_verify;
249: if (req_verify && (sig_details->sk_flags &
250: SSH_SK_USER_VERIFICATION_REQD) == 0) {
251: error("public key %s signature for %s%s from "
252: "%.128s port %d rejected: user "
253: "verification requirement not met ", key_s,
1.96 djm 254: authctxt->valid ? "" : "invalid user ",
255: authctxt->user, ssh_remote_ipaddr(ssh),
256: ssh_remote_port(ssh));
257: authenticated = 0;
258: goto done;
259: }
1.95 djm 260: }
1.68 djm 261: auth2_record_key(authctxt, authenticated, key);
1.1 markus 262: } else {
1.112 djm 263: debug_f("%s test pkalg %s pkblob %s%s%s", method, pkalg, key_s,
1.101 djm 264: ca_s == NULL ? "" : " CA ", ca_s == NULL ? "" : ca_s);
1.73 djm 265:
1.64 markus 266: if ((r = sshpkt_get_end(ssh)) != 0)
1.101 djm 267: fatal_fr(r, "parse packet");
1.1 markus 268:
1.83 djm 269: if (!authctxt->valid || authctxt->user == NULL) {
1.101 djm 270: debug2_f("disabled because of invalid user");
1.83 djm 271: goto done;
272: }
1.1 markus 273: /* XXX fake reply and always send PK_OK ? */
274: /*
275: * XXX this allows testing whether a user is allowed
276: * to login: if you happen to have a valid pubkey this
277: * message is sent. the message is NEVER sent at all
278: * if a user is not allowed to login. is this an
279: * issue? -markus
280: */
1.116 djm 281: if (PRIVSEP(user_key_allowed(ssh, pw, key, 0, NULL))) {
1.64 markus 282: if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_PK_OK))
283: != 0 ||
284: (r = sshpkt_put_cstring(ssh, pkalg)) != 0 ||
285: (r = sshpkt_put_string(ssh, pkblob, blen)) != 0 ||
1.82 markus 286: (r = sshpkt_send(ssh)) != 0 ||
287: (r = ssh_packet_write_wait(ssh)) != 0)
1.101 djm 288: fatal_fr(r, "send packet");
1.1 markus 289: authctxt->postponed = 1;
290: }
291: }
292: done:
1.77 djm 293: if (authenticated == 1 && auth_activate_options(ssh, authopts) != 0) {
1.101 djm 294: debug_f("key options inconsistent with existing");
1.77 djm 295: authenticated = 0;
296: }
1.101 djm 297: debug2_f("authenticated %d pkalg %s", authenticated, pkalg);
1.77 djm 298:
1.84 djm 299: sshbuf_free(b);
1.77 djm 300: sshauthopt_free(authopts);
1.68 djm 301: sshkey_free(key);
1.112 djm 302: sshkey_free(hostkey);
1.64 markus 303: free(userstyle);
1.36 djm 304: free(pkalg);
305: free(pkblob);
1.73 djm 306: free(key_s);
307: free(ca_s);
1.83 djm 308: free(sig);
1.95 djm 309: sshkey_sig_details_free(sig_details);
1.1 markus 310: return authenticated;
311: }
312:
1.24 djm 313: static int
1.114 djm 314: match_principals_file(struct passwd *pw, char *file,
1.77 djm 315: struct sshkey_cert *cert, struct sshauthopt **authoptsp)
1.51 djm 316: {
317: FILE *f;
318: int success;
319:
1.77 djm 320: if (authoptsp != NULL)
321: *authoptsp = NULL;
322:
1.51 djm 323: temporarily_use_uid(pw);
324: debug("trying authorized principals file %s", file);
325: if ((f = auth_openprincipals(file, pw, options.strict_modes)) == NULL) {
326: restore_uid();
327: return 0;
328: }
1.115 djm 329: success = auth_process_principals(f, file, cert, authoptsp);
1.24 djm 330: fclose(f);
331: restore_uid();
1.51 djm 332: return success;
1.31 djm 333: }
1.24 djm 334:
1.31 djm 335: /*
1.51 djm 336: * Checks whether principal is allowed in output of command.
337: * returns 1 if the principal is allowed or 0 otherwise.
338: */
339: static int
1.119 ! djm 340: match_principals_command(struct passwd *user_pw, const struct sshkey *key,
! 341: const char *conn_id, const char *rdomain, struct sshauthopt **authoptsp)
1.51 djm 342: {
1.77 djm 343: struct passwd *runas_pw = NULL;
1.56 djm 344: const struct sshkey_cert *cert = key->cert;
1.51 djm 345: FILE *f = NULL;
1.56 djm 346: int r, ok, found_principal = 0;
1.51 djm 347: int i, ac = 0, uid_swapped = 0;
348: pid_t pid;
349: char *tmp, *username = NULL, *command = NULL, **av = NULL;
1.56 djm 350: char *ca_fp = NULL, *key_fp = NULL, *catext = NULL, *keytext = NULL;
1.88 djm 351: char serial_s[32], uidstr[32];
1.51 djm 352: void (*osigchld)(int);
353:
1.77 djm 354: if (authoptsp != NULL)
355: *authoptsp = NULL;
1.51 djm 356: if (options.authorized_principals_command == NULL)
357: return 0;
358: if (options.authorized_principals_command_user == NULL) {
359: error("No user for AuthorizedPrincipalsCommand specified, "
360: "skipping");
361: return 0;
362: }
363:
364: /*
365: * NB. all returns later this function should go via "out" to
366: * ensure the original SIGCHLD handler is restored properly.
367: */
1.98 dtucker 368: osigchld = ssh_signal(SIGCHLD, SIG_DFL);
1.51 djm 369:
370: /* Prepare and verify the user for the command */
371: username = percent_expand(options.authorized_principals_command_user,
372: "u", user_pw->pw_name, (char *)NULL);
1.77 djm 373: runas_pw = getpwnam(username);
374: if (runas_pw == NULL) {
1.51 djm 375: error("AuthorizedPrincipalsCommandUser \"%s\" not found: %s",
376: username, strerror(errno));
377: goto out;
378: }
379:
380: /* Turn the command into an argument vector */
1.108 djm 381: if (argv_split(options.authorized_principals_command,
382: &ac, &av, 0) != 0) {
1.51 djm 383: error("AuthorizedPrincipalsCommand \"%s\" contains "
1.90 djm 384: "invalid quotes", options.authorized_principals_command);
1.51 djm 385: goto out;
386: }
387: if (ac == 0) {
388: error("AuthorizedPrincipalsCommand \"%s\" yielded no arguments",
1.90 djm 389: options.authorized_principals_command);
1.51 djm 390: goto out;
391: }
1.56 djm 392: if ((ca_fp = sshkey_fingerprint(cert->signature_key,
393: options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) {
1.101 djm 394: error_f("sshkey_fingerprint failed");
1.56 djm 395: goto out;
396: }
1.57 djm 397: if ((key_fp = sshkey_fingerprint(key,
1.56 djm 398: options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) {
1.101 djm 399: error_f("sshkey_fingerprint failed");
1.56 djm 400: goto out;
401: }
402: if ((r = sshkey_to_base64(cert->signature_key, &catext)) != 0) {
1.101 djm 403: error_fr(r, "sshkey_to_base64 failed");
1.56 djm 404: goto out;
405: }
406: if ((r = sshkey_to_base64(key, &keytext)) != 0) {
1.101 djm 407: error_fr(r, "sshkey_to_base64 failed");
1.56 djm 408: goto out;
409: }
1.59 djm 410: snprintf(serial_s, sizeof(serial_s), "%llu",
411: (unsigned long long)cert->serial);
1.78 djm 412: snprintf(uidstr, sizeof(uidstr), "%llu",
413: (unsigned long long)user_pw->pw_uid);
1.51 djm 414: for (i = 1; i < ac; i++) {
415: tmp = percent_expand(av[i],
1.119 ! djm 416: "C", conn_id,
! 417: "D", rdomain,
1.78 djm 418: "U", uidstr,
1.51 djm 419: "u", user_pw->pw_name,
420: "h", user_pw->pw_dir,
1.56 djm 421: "t", sshkey_ssh_name(key),
422: "T", sshkey_ssh_name(cert->signature_key),
423: "f", key_fp,
424: "F", ca_fp,
425: "k", keytext,
426: "K", catext,
1.58 djm 427: "i", cert->key_id,
428: "s", serial_s,
1.51 djm 429: (char *)NULL);
430: if (tmp == NULL)
1.101 djm 431: fatal_f("percent_expand failed");
1.51 djm 432: free(av[i]);
433: av[i] = tmp;
434: }
435: /* Prepare a printable command for logs, etc. */
1.69 djm 436: command = argv_assemble(ac, av);
1.51 djm 437:
1.103 djm 438: if ((pid = subprocess("AuthorizedPrincipalsCommand", command,
1.69 djm 439: ac, av, &f,
1.103 djm 440: SSH_SUBPROCESS_STDOUT_CAPTURE|SSH_SUBPROCESS_STDERR_DISCARD,
441: runas_pw, temporarily_use_uid, restore_uid)) == 0)
1.51 djm 442: goto out;
443:
444: uid_swapped = 1;
1.77 djm 445: temporarily_use_uid(runas_pw);
1.51 djm 446:
1.115 djm 447: ok = auth_process_principals(f, "(command)", cert, authoptsp);
1.51 djm 448:
1.61 djm 449: fclose(f);
450: f = NULL;
451:
1.70 djm 452: if (exited_cleanly(pid, "AuthorizedPrincipalsCommand", command, 0) != 0)
1.51 djm 453: goto out;
454:
455: /* Read completed successfully */
456: found_principal = ok;
457: out:
458: if (f != NULL)
459: fclose(f);
1.98 dtucker 460: ssh_signal(SIGCHLD, osigchld);
1.51 djm 461: for (i = 0; i < ac; i++)
462: free(av[i]);
463: free(av);
464: if (uid_swapped)
465: restore_uid();
466: free(command);
467: free(username);
1.56 djm 468: free(ca_fp);
469: free(key_fp);
470: free(catext);
471: free(keytext);
1.51 djm 472: return found_principal;
1.77 djm 473: }
474:
1.21 djm 475: /* Authenticate a certificate key against TrustedUserCAKeys */
476: static int
1.114 djm 477: user_cert_trusted_ca(struct passwd *pw, struct sshkey *key,
478: const char *remote_ip, const char *remote_host,
1.119 ! djm 479: const char *conn_id, const char *rdomain, struct sshauthopt **authoptsp)
1.21 djm 480: {
1.24 djm 481: char *ca_fp, *principals_file = NULL;
1.21 djm 482: const char *reason;
1.77 djm 483: struct sshauthopt *principals_opts = NULL, *cert_opts = NULL;
484: struct sshauthopt *final_opts = NULL;
1.64 markus 485: int r, ret = 0, found_principal = 0, use_authorized_principals;
1.21 djm 486:
1.77 djm 487: if (authoptsp != NULL)
488: *authoptsp = NULL;
489:
1.64 markus 490: if (!sshkey_is_cert(key) || options.trusted_user_ca_keys == NULL)
1.21 djm 491: return 0;
492:
1.46 djm 493: if ((ca_fp = sshkey_fingerprint(key->cert->signature_key,
494: options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL)
495: return 0;
1.21 djm 496:
1.64 markus 497: if ((r = sshkey_in_file(key->cert->signature_key,
498: options.trusted_user_ca_keys, 1, 0)) != 0) {
1.101 djm 499: debug2_fr(r, "CA %s %s is not listed in %s",
1.64 markus 500: sshkey_type(key->cert->signature_key), ca_fp,
1.101 djm 501: options.trusted_user_ca_keys);
1.21 djm 502: goto out;
503: }
1.24 djm 504: /*
505: * If AuthorizedPrincipals is in use, then compare the certificate
506: * principals against the names in that file rather than matching
507: * against the username.
508: */
509: if ((principals_file = authorized_principals_file(pw)) != NULL) {
1.114 djm 510: if (match_principals_file(pw, principals_file,
1.77 djm 511: key->cert, &principals_opts))
1.51 djm 512: found_principal = 1;
513: }
514: /* Try querying command if specified */
1.114 djm 515: if (!found_principal && match_principals_command(pw, key,
1.119 ! djm 516: conn_id, rdomain, &principals_opts))
1.51 djm 517: found_principal = 1;
1.53 jsing 518: /* If principals file or command is specified, then require a match */
519: use_authorized_principals = principals_file != NULL ||
1.107 djm 520: options.authorized_principals_command != NULL;
1.53 jsing 521: if (!found_principal && use_authorized_principals) {
1.51 djm 522: reason = "Certificate does not contain an authorized principal";
1.77 djm 523: goto fail_reason;
1.21 djm 524: }
1.77 djm 525: if (use_authorized_principals && principals_opts == NULL)
1.101 djm 526: fatal_f("internal error: missing principals_opts");
1.109 djm 527: if (sshkey_cert_check_authority_now(key, 0, 1, 0,
1.53 jsing 528: use_authorized_principals ? NULL : pw->pw_name, &reason) != 0)
1.24 djm 529: goto fail_reason;
1.77 djm 530:
531: /* Check authority from options in key and from principals file/cmd */
532: if ((cert_opts = sshauthopt_from_cert(key)) == NULL) {
533: reason = "Invalid certificate options";
534: goto fail_reason;
535: }
1.114 djm 536: if (auth_authorise_keyopts(pw, cert_opts, 0,
537: remote_ip, remote_host, "cert") != 0) {
1.77 djm 538: reason = "Refused by certificate options";
1.60 djm 539: goto fail_reason;
1.77 djm 540: }
541: if (principals_opts == NULL) {
542: final_opts = cert_opts;
543: cert_opts = NULL;
544: } else {
1.114 djm 545: if (auth_authorise_keyopts(pw, principals_opts, 0,
546: remote_ip, remote_host, "principals") != 0) {
1.77 djm 547: reason = "Refused by certificate principals options";
548: goto fail_reason;
549: }
550: if ((final_opts = sshauthopt_merge(principals_opts,
551: cert_opts, &reason)) == NULL) {
552: fail_reason:
553: error("%s", reason);
554: auth_debug_add("%s", reason);
555: goto out;
556: }
557: }
1.21 djm 558:
1.77 djm 559: /* Success */
1.54 djm 560: verbose("Accepted certificate ID \"%s\" (serial %llu) signed by "
561: "%s CA %s via %s", key->cert->key_id,
562: (unsigned long long)key->cert->serial,
1.64 markus 563: sshkey_type(key->cert->signature_key), ca_fp,
1.22 djm 564: options.trusted_user_ca_keys);
1.77 djm 565: if (authoptsp != NULL) {
566: *authoptsp = final_opts;
567: final_opts = NULL;
568: }
1.21 djm 569: ret = 1;
570: out:
1.77 djm 571: sshauthopt_free(principals_opts);
572: sshauthopt_free(cert_opts);
573: sshauthopt_free(final_opts);
1.36 djm 574: free(principals_file);
575: free(ca_fp);
1.21 djm 576: return ret;
577: }
578:
1.31 djm 579: /*
580: * Checks whether key is allowed in file.
581: * returns 1 if the key is allowed or 0 otherwise.
582: */
583: static int
1.114 djm 584: user_key_allowed2(struct passwd *pw, struct sshkey *key,
585: char *file, const char *remote_ip, const char *remote_host,
586: struct sshauthopt **authoptsp)
1.31 djm 587: {
588: FILE *f;
589: int found_key = 0;
590:
1.77 djm 591: if (authoptsp != NULL)
592: *authoptsp = NULL;
593:
1.31 djm 594: /* Temporarily use the user's uid. */
595: temporarily_use_uid(pw);
596:
597: debug("trying public key file %s", file);
598: if ((f = auth_openkeyfile(file, pw, options.strict_modes)) != NULL) {
1.115 djm 599: found_key = auth_check_authkeys_file(pw, f, file,
1.114 djm 600: key, remote_ip, remote_host, authoptsp);
1.31 djm 601: fclose(f);
602: }
603:
604: restore_uid();
605: return found_key;
606: }
607:
608: /*
609: * Checks whether key is allowed in output of command.
610: * returns 1 if the key is allowed or 0 otherwise.
611: */
612: static int
1.114 djm 613: user_key_command_allowed2(struct passwd *user_pw, struct sshkey *key,
614: const char *remote_ip, const char *remote_host,
1.119 ! djm 615: const char *conn_id, const char *rdomain, struct sshauthopt **authoptsp)
1.31 djm 616: {
1.77 djm 617: struct passwd *runas_pw = NULL;
1.50 djm 618: FILE *f = NULL;
619: int r, ok, found_key = 0;
620: int i, uid_swapped = 0, ac = 0;
1.31 djm 621: pid_t pid;
1.50 djm 622: char *username = NULL, *key_fp = NULL, *keytext = NULL;
1.78 djm 623: char uidstr[32], *tmp, *command = NULL, **av = NULL;
1.50 djm 624: void (*osigchld)(int);
1.31 djm 625:
1.77 djm 626: if (authoptsp != NULL)
627: *authoptsp = NULL;
1.50 djm 628: if (options.authorized_keys_command == NULL)
1.31 djm 629: return 0;
1.32 djm 630: if (options.authorized_keys_command_user == NULL) {
631: error("No user for AuthorizedKeysCommand specified, skipping");
632: return 0;
633: }
634:
1.50 djm 635: /*
636: * NB. all returns later this function should go via "out" to
637: * ensure the original SIGCHLD handler is restored properly.
638: */
1.98 dtucker 639: osigchld = ssh_signal(SIGCHLD, SIG_DFL);
1.50 djm 640:
641: /* Prepare and verify the user for the command */
1.32 djm 642: username = percent_expand(options.authorized_keys_command_user,
643: "u", user_pw->pw_name, (char *)NULL);
1.77 djm 644: runas_pw = getpwnam(username);
645: if (runas_pw == NULL) {
1.34 djm 646: error("AuthorizedKeysCommandUser \"%s\" not found: %s",
647: username, strerror(errno));
1.50 djm 648: goto out;
1.31 djm 649: }
650:
1.50 djm 651: /* Prepare AuthorizedKeysCommand */
652: if ((key_fp = sshkey_fingerprint(key, options.fingerprint_hash,
653: SSH_FP_DEFAULT)) == NULL) {
1.101 djm 654: error_f("sshkey_fingerprint failed");
1.31 djm 655: goto out;
656: }
1.50 djm 657: if ((r = sshkey_to_base64(key, &keytext)) != 0) {
1.101 djm 658: error_fr(r, "sshkey_to_base64 failed");
1.31 djm 659: goto out;
660: }
661:
1.50 djm 662: /* Turn the command into an argument vector */
1.108 djm 663: if (argv_split(options.authorized_keys_command, &ac, &av, 0) != 0) {
1.50 djm 664: error("AuthorizedKeysCommand \"%s\" contains invalid quotes",
1.102 djm 665: options.authorized_keys_command);
1.50 djm 666: goto out;
667: }
668: if (ac == 0) {
669: error("AuthorizedKeysCommand \"%s\" yielded no arguments",
1.102 djm 670: options.authorized_keys_command);
1.31 djm 671: goto out;
672: }
1.78 djm 673: snprintf(uidstr, sizeof(uidstr), "%llu",
674: (unsigned long long)user_pw->pw_uid);
1.50 djm 675: for (i = 1; i < ac; i++) {
676: tmp = percent_expand(av[i],
1.119 ! djm 677: "C", conn_id,
! 678: "D", rdomain,
1.78 djm 679: "U", uidstr,
1.50 djm 680: "u", user_pw->pw_name,
681: "h", user_pw->pw_dir,
682: "t", sshkey_ssh_name(key),
683: "f", key_fp,
684: "k", keytext,
685: (char *)NULL);
686: if (tmp == NULL)
1.101 djm 687: fatal_f("percent_expand failed");
1.50 djm 688: free(av[i]);
689: av[i] = tmp;
690: }
691: /* Prepare a printable command for logs, etc. */
1.69 djm 692: command = argv_assemble(ac, av);
1.31 djm 693:
694: /*
1.50 djm 695: * If AuthorizedKeysCommand was run without arguments
696: * then fall back to the old behaviour of passing the
697: * target username as a single argument.
1.31 djm 698: */
1.50 djm 699: if (ac == 1) {
700: av = xreallocarray(av, ac + 2, sizeof(*av));
701: av[1] = xstrdup(user_pw->pw_name);
702: av[2] = NULL;
703: /* Fix up command too, since it is used in log messages */
704: free(command);
705: xasprintf(&command, "%s %s", av[0], av[1]);
706: }
1.31 djm 707:
1.103 djm 708: if ((pid = subprocess("AuthorizedKeysCommand", command,
1.69 djm 709: ac, av, &f,
1.103 djm 710: SSH_SUBPROCESS_STDOUT_CAPTURE|SSH_SUBPROCESS_STDERR_DISCARD,
711: runas_pw, temporarily_use_uid, restore_uid)) == 0)
1.50 djm 712: goto out;
1.31 djm 713:
1.50 djm 714: uid_swapped = 1;
1.77 djm 715: temporarily_use_uid(runas_pw);
1.31 djm 716:
1.115 djm 717: ok = auth_check_authkeys_file(user_pw, f,
1.114 djm 718: options.authorized_keys_command, key, remote_ip,
719: remote_host, authoptsp);
1.61 djm 720:
721: fclose(f);
722: f = NULL;
1.31 djm 723:
1.70 djm 724: if (exited_cleanly(pid, "AuthorizedKeysCommand", command, 0) != 0)
1.31 djm 725: goto out;
1.50 djm 726:
727: /* Read completed successfully */
1.31 djm 728: found_key = ok;
729: out:
1.50 djm 730: if (f != NULL)
731: fclose(f);
1.98 dtucker 732: ssh_signal(SIGCHLD, osigchld);
1.50 djm 733: for (i = 0; i < ac; i++)
734: free(av[i]);
735: free(av);
736: if (uid_swapped)
737: restore_uid();
738: free(command);
739: free(username);
740: free(key_fp);
741: free(keytext);
1.31 djm 742: return found_key;
743: }
744:
745: /*
746: * Check whether key authenticates and authorises the user.
747: */
1.1 markus 748: int
1.116 djm 749: user_key_allowed(struct ssh *ssh, struct passwd *pw, struct sshkey *key,
750: int auth_attempt, struct sshauthopt **authoptsp)
1.1 markus 751: {
1.89 djm 752: u_int success = 0, i;
1.119 ! djm 753: char *file, *conn_id;
1.77 djm 754: struct sshauthopt *opts = NULL;
1.119 ! djm 755: const char *rdomain, *remote_ip, *remote_host;
1.89 djm 756:
1.77 djm 757: if (authoptsp != NULL)
758: *authoptsp = NULL;
1.21 djm 759:
760: if (auth_key_is_revoked(key))
761: return 0;
1.64 markus 762: if (sshkey_is_cert(key) &&
763: auth_key_is_revoked(key->cert->signature_key))
1.21 djm 764: return 0;
765:
1.119 ! djm 766: if ((rdomain = ssh_packet_rdomain_in(ssh)) == NULL)
! 767: rdomain = "";
! 768: remote_ip = ssh_remote_ipaddr(ssh);
! 769: remote_host = auth_get_canonical_hostname(ssh, options.use_dns);
! 770: xasprintf(&conn_id, "%s %d %s %d",
! 771: ssh_local_ipaddr(ssh), ssh_local_port(ssh),
! 772: remote_ip, ssh_remote_port(ssh));
! 773:
1.89 djm 774: for (i = 0; !success && i < options.num_authkeys_files; i++) {
775: if (strcasecmp(options.authorized_keys_files[i], "none") == 0)
776: continue;
777: file = expand_authorized_keys(
778: options.authorized_keys_files[i], pw);
1.114 djm 779: success = user_key_allowed2(pw, key, file,
780: remote_ip, remote_host, &opts);
1.89 djm 781: free(file);
782: if (!success) {
783: sshauthopt_free(opts);
784: opts = NULL;
785: }
786: }
787: if (success)
788: goto out;
789:
1.114 djm 790: if ((success = user_cert_trusted_ca(pw, key, remote_ip, remote_host,
1.119 ! djm 791: conn_id, rdomain, &opts)) != 0)
1.77 djm 792: goto out;
793: sshauthopt_free(opts);
794: opts = NULL;
795:
1.114 djm 796: if ((success = user_key_command_allowed2(pw, key, remote_ip,
1.119 ! djm 797: remote_host, conn_id, rdomain, &opts)) != 0)
1.77 djm 798: goto out;
799: sshauthopt_free(opts);
800: opts = NULL;
1.1 markus 801:
1.77 djm 802: out:
1.119 ! djm 803: free(conn_id);
1.77 djm 804: if (success && authoptsp != NULL) {
805: *authoptsp = opts;
806: opts = NULL;
807: }
808: sshauthopt_free(opts);
1.1 markus 809: return success;
810: }
1.2 markus 811:
812: Authmethod method_pubkey = {
813: "publickey",
1.112 djm 814: "publickey-hostbound-v00@openssh.com",
1.2 markus 815: userauth_pubkey,
816: &options.pubkey_authentication
817: };
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