Annotation of src/usr.bin/ssh/auth2-pubkey.c, Revision 1.112
1.112 ! djm 1: /* $OpenBSD: auth2-pubkey.c,v 1.111 2021/12/19 22:12:07 djm Exp $ */
1.1 markus 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:
1.10 stevesk 26:
27: #include <sys/types.h>
28: #include <sys/stat.h>
1.13 stevesk 29:
1.94 djm 30: #include <stdlib.h>
1.31 djm 31: #include <errno.h>
1.16 djm 32: #include <fcntl.h>
1.31 djm 33: #include <paths.h>
1.13 stevesk 34: #include <pwd.h>
1.31 djm 35: #include <signal.h>
1.14 stevesk 36: #include <stdio.h>
1.15 deraadt 37: #include <stdarg.h>
1.20 djm 38: #include <string.h>
39: #include <time.h>
1.17 dtucker 40: #include <unistd.h>
1.44 djm 41: #include <limits.h>
1.1 markus 42:
1.15 deraadt 43: #include "xmalloc.h"
1.8 dtucker 44: #include "ssh.h"
1.1 markus 45: #include "ssh2.h"
46: #include "packet.h"
1.106 djm 47: #include "kex.h"
1.81 markus 48: #include "sshbuf.h"
1.1 markus 49: #include "log.h"
1.41 millert 50: #include "misc.h"
1.1 markus 51: #include "servconf.h"
52: #include "compat.h"
1.64 markus 53: #include "sshkey.h"
1.15 deraadt 54: #include "hostfile.h"
1.1 markus 55: #include "auth.h"
56: #include "pathnames.h"
57: #include "uidswap.h"
58: #include "auth-options.h"
59: #include "canohost.h"
1.15 deraadt 60: #ifdef GSSAPI
61: #include "ssh-gss.h"
62: #endif
1.1 markus 63: #include "monitor_wrap.h"
1.21 djm 64: #include "authfile.h"
1.24 djm 65: #include "match.h"
1.50 djm 66: #include "ssherr.h"
1.112 ! djm 67: #include "kex.h"
1.50 djm 68: #include "channels.h" /* XXX for session.h */
69: #include "session.h" /* XXX for child_set_env(); refactor? */
1.96 djm 70: #include "sk-api.h"
1.1 markus 71:
72: /* import */
73: extern ServerOptions options;
74:
1.73 djm 75: static char *
76: format_key(const struct sshkey *key)
77: {
78: char *ret, *fp = sshkey_fingerprint(key,
79: options.fingerprint_hash, SSH_FP_DEFAULT);
80:
81: xasprintf(&ret, "%s %s", sshkey_type(key), fp);
82: free(fp);
83: return ret;
84: }
85:
1.2 markus 86: static int
1.111 djm 87: userauth_pubkey(struct ssh *ssh, const char *method)
1.1 markus 88: {
1.65 markus 89: Authctxt *authctxt = ssh->authctxt;
1.77 djm 90: struct passwd *pw = authctxt->pw;
1.83 djm 91: struct sshbuf *b = NULL;
1.112 ! djm 92: struct sshkey *key = NULL, *hostkey = NULL;
1.83 djm 93: char *pkalg = NULL, *userstyle = NULL, *key_s = NULL, *ca_s = NULL;
94: u_char *pkblob = NULL, *sig = NULL, have_sig;
1.64 markus 95: size_t blen, slen;
1.112 ! djm 96: int hostbound, r, pktype;
1.100 djm 97: int req_presence = 0, req_verify = 0, authenticated = 0;
1.77 djm 98: struct sshauthopt *authopts = NULL;
1.95 djm 99: struct sshkey_sig_details *sig_details = NULL;
1.1 markus 100:
1.112 ! djm 101: hostbound = strcmp(method, "publickey-hostbound-v00@openssh.com") == 0;
! 102:
1.75 djm 103: if ((r = sshpkt_get_u8(ssh, &have_sig)) != 0 ||
104: (r = sshpkt_get_cstring(ssh, &pkalg, NULL)) != 0 ||
105: (r = sshpkt_get_string(ssh, &pkblob, &blen)) != 0)
1.112 ! djm 106: fatal_fr(r, "parse %s packet", method);
! 107:
! 108: /* hostbound auth includes the hostkey offered at initial KEX */
! 109: if (hostbound) {
! 110: if ((r = sshpkt_getb_froms(ssh, &b)) != 0 ||
! 111: (r = sshkey_fromb(b, &hostkey)) != 0)
! 112: fatal_fr(r, "parse %s hostkey", method);
! 113: if (ssh->kex->initial_hostkey == NULL)
! 114: fatal_f("internal error: initial hostkey not recorded");
! 115: if (!sshkey_equal(hostkey, ssh->kex->initial_hostkey))
! 116: fatal_f("%s packet contained wrong host key", method);
! 117: sshbuf_free(b);
! 118: b = NULL;
! 119: }
1.87 djm 120:
121: if (log_level_get() >= SYSLOG_LEVEL_DEBUG2) {
122: char *keystring;
123: struct sshbuf *pkbuf;
124:
125: if ((pkbuf = sshbuf_from(pkblob, blen)) == NULL)
1.101 djm 126: fatal_f("sshbuf_from failed");
1.91 djm 127: if ((keystring = sshbuf_dtob64_string(pkbuf, 0)) == NULL)
1.101 djm 128: fatal_f("sshbuf_dtob64 failed");
129: debug2_f("%s user %s %s public key %s %s",
1.87 djm 130: authctxt->valid ? "valid" : "invalid", authctxt->user,
131: have_sig ? "attempting" : "querying", pkalg, keystring);
132: sshbuf_free(pkbuf);
133: free(keystring);
134: }
135:
1.64 markus 136: pktype = sshkey_type_from_name(pkalg);
1.1 markus 137: if (pktype == KEY_UNSPEC) {
138: /* this is perfectly legal */
1.101 djm 139: verbose_f("unsupported public key algorithm: %s", pkalg);
1.1 markus 140: goto done;
141: }
1.64 markus 142: if ((r = sshkey_from_blob(pkblob, blen, &key)) != 0) {
1.101 djm 143: error_fr(r, "parse key");
1.64 markus 144: goto done;
145: }
1.1 markus 146: if (key == NULL) {
1.101 djm 147: error_f("cannot decode key: %s", pkalg);
1.1 markus 148: goto done;
149: }
150: if (key->type != pktype) {
1.101 djm 151: error_f("type mismatch for decoded key "
152: "(received %d, expected %d)", key->type, pktype);
1.39 djm 153: goto done;
154: }
1.64 markus 155: if (sshkey_type_plain(key->type) == KEY_RSA &&
156: (ssh->compat & SSH_BUG_RSASIGMD5) != 0) {
1.39 djm 157: logit("Refusing RSA key because client uses unsafe "
158: "signature scheme");
1.1 markus 159: goto done;
160: }
1.68 djm 161: if (auth2_key_already_used(authctxt, key)) {
1.64 markus 162: logit("refusing previously-used %s key", sshkey_type(key));
1.44 djm 163: goto done;
164: }
1.104 dtucker 165: if (match_pattern_list(pkalg, options.pubkey_accepted_algos, 0) != 1) {
166: logit_f("key type %s not in PubkeyAcceptedAlgorithms",
1.101 djm 167: sshkey_ssh_name(key));
1.45 djm 168: goto done;
169: }
1.86 djm 170: if ((r = sshkey_check_cert_sigtype(key,
171: options.ca_sign_algorithms)) != 0) {
1.101 djm 172: logit_fr(r, "certificate signature algorithm %s",
1.86 djm 173: (key->cert == NULL || key->cert->signature_type == NULL) ?
1.101 djm 174: "(null)" : key->cert->signature_type);
1.86 djm 175: goto done;
176: }
1.73 djm 177: key_s = format_key(key);
178: if (sshkey_is_cert(key))
179: ca_s = format_key(key->cert->signature_key);
180:
1.1 markus 181: if (have_sig) {
1.112 ! djm 182: debug3_f("%s have %s signature for %s%s%s",
! 183: method, pkalg, key_s,
1.101 djm 184: ca_s == NULL ? "" : " CA ", ca_s == NULL ? "" : ca_s);
1.64 markus 185: if ((r = sshpkt_get_string(ssh, &sig, &slen)) != 0 ||
186: (r = sshpkt_get_end(ssh)) != 0)
1.101 djm 187: fatal_fr(r, "parse signature packet");
1.64 markus 188: if ((b = sshbuf_new()) == NULL)
1.101 djm 189: fatal_f("sshbuf_new failed");
1.64 markus 190: if (ssh->compat & SSH_OLD_SESSIONID) {
1.106 djm 191: if ((r = sshbuf_putb(b, ssh->kex->session_id)) != 0)
1.101 djm 192: fatal_fr(r, "put old session id");
1.1 markus 193: } else {
1.106 djm 194: if ((r = sshbuf_put_stringb(b,
195: ssh->kex->session_id)) != 0)
1.101 djm 196: fatal_fr(r, "put session id");
1.1 markus 197: }
1.83 djm 198: if (!authctxt->valid || authctxt->user == NULL) {
1.101 djm 199: debug2_f("disabled because of invalid user");
1.83 djm 200: goto done;
201: }
1.1 markus 202: /* reconstruct packet */
1.35 djm 203: xasprintf(&userstyle, "%s%s%s", authctxt->user,
204: authctxt->style ? ":" : "",
205: authctxt->style ? authctxt->style : "");
1.64 markus 206: if ((r = sshbuf_put_u8(b, SSH2_MSG_USERAUTH_REQUEST)) != 0 ||
207: (r = sshbuf_put_cstring(b, userstyle)) != 0 ||
1.75 djm 208: (r = sshbuf_put_cstring(b, authctxt->service)) != 0 ||
1.111 djm 209: (r = sshbuf_put_cstring(b, method)) != 0 ||
1.75 djm 210: (r = sshbuf_put_u8(b, have_sig)) != 0 ||
1.85 mestre 211: (r = sshbuf_put_cstring(b, pkalg)) != 0 ||
1.75 djm 212: (r = sshbuf_put_string(b, pkblob, blen)) != 0)
1.112 ! djm 213: fatal_fr(r, "reconstruct %s packet", method);
! 214: if (hostbound &&
! 215: (r = sshkey_puts(ssh->kex->initial_hostkey, b)) != 0)
! 216: fatal_fr(r, "reconstruct %s packet", method);
1.1 markus 217: #ifdef DEBUG_PK
1.64 markus 218: sshbuf_dump(b, stderr);
1.1 markus 219: #endif
220: /* test for correct signature */
221: authenticated = 0;
1.77 djm 222: if (PRIVSEP(user_key_allowed(ssh, pw, key, 1, &authopts)) &&
1.80 djm 223: PRIVSEP(sshkey_verify(key, sig, slen,
224: sshbuf_ptr(b), sshbuf_len(b),
225: (ssh->compat & SSH_BUG_SIGTYPE) == 0 ? pkalg : NULL,
1.95 djm 226: ssh->compat, &sig_details)) == 0) {
1.1 markus 227: authenticated = 1;
1.44 djm 228: }
1.96 djm 229: if (authenticated == 1 && sig_details != NULL) {
230: auth2_record_info(authctxt, "signature count = %u",
231: sig_details->sk_counter);
1.101 djm 232: debug_f("sk_counter = %u, sk_flags = 0x%02x",
233: sig_details->sk_counter, sig_details->sk_flags);
1.96 djm 234: req_presence = (options.pubkey_auth_options &
1.97 djm 235: PUBKEYAUTH_TOUCH_REQUIRED) ||
236: !authopts->no_require_user_presence;
1.96 djm 237: if (req_presence && (sig_details->sk_flags &
238: SSH_SK_USER_PRESENCE_REQD) == 0) {
239: error("public key %s signature for %s%s from "
240: "%.128s port %d rejected: user presence "
1.99 naddy 241: "(authenticator touch) requirement "
242: "not met ", key_s,
1.100 djm 243: authctxt->valid ? "" : "invalid user ",
244: authctxt->user, ssh_remote_ipaddr(ssh),
245: ssh_remote_port(ssh));
246: authenticated = 0;
247: goto done;
248: }
249: req_verify = (options.pubkey_auth_options &
250: PUBKEYAUTH_VERIFY_REQUIRED) ||
251: authopts->require_verify;
252: if (req_verify && (sig_details->sk_flags &
253: SSH_SK_USER_VERIFICATION_REQD) == 0) {
254: error("public key %s signature for %s%s from "
255: "%.128s port %d rejected: user "
256: "verification requirement not met ", key_s,
1.96 djm 257: authctxt->valid ? "" : "invalid user ",
258: authctxt->user, ssh_remote_ipaddr(ssh),
259: ssh_remote_port(ssh));
260: authenticated = 0;
261: goto done;
262: }
1.95 djm 263: }
1.68 djm 264: auth2_record_key(authctxt, authenticated, key);
1.1 markus 265: } else {
1.112 ! djm 266: debug_f("%s test pkalg %s pkblob %s%s%s", method, pkalg, key_s,
1.101 djm 267: ca_s == NULL ? "" : " CA ", ca_s == NULL ? "" : ca_s);
1.73 djm 268:
1.64 markus 269: if ((r = sshpkt_get_end(ssh)) != 0)
1.101 djm 270: fatal_fr(r, "parse packet");
1.1 markus 271:
1.83 djm 272: if (!authctxt->valid || authctxt->user == NULL) {
1.101 djm 273: debug2_f("disabled because of invalid user");
1.83 djm 274: goto done;
275: }
1.1 markus 276: /* XXX fake reply and always send PK_OK ? */
277: /*
278: * XXX this allows testing whether a user is allowed
279: * to login: if you happen to have a valid pubkey this
280: * message is sent. the message is NEVER sent at all
281: * if a user is not allowed to login. is this an
282: * issue? -markus
283: */
1.77 djm 284: if (PRIVSEP(user_key_allowed(ssh, pw, key, 0, NULL))) {
1.64 markus 285: if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_PK_OK))
286: != 0 ||
287: (r = sshpkt_put_cstring(ssh, pkalg)) != 0 ||
288: (r = sshpkt_put_string(ssh, pkblob, blen)) != 0 ||
1.82 markus 289: (r = sshpkt_send(ssh)) != 0 ||
290: (r = ssh_packet_write_wait(ssh)) != 0)
1.101 djm 291: fatal_fr(r, "send packet");
1.1 markus 292: authctxt->postponed = 1;
293: }
294: }
295: done:
1.77 djm 296: if (authenticated == 1 && auth_activate_options(ssh, authopts) != 0) {
1.101 djm 297: debug_f("key options inconsistent with existing");
1.77 djm 298: authenticated = 0;
299: }
1.101 djm 300: debug2_f("authenticated %d pkalg %s", authenticated, pkalg);
1.77 djm 301:
1.84 djm 302: sshbuf_free(b);
1.77 djm 303: sshauthopt_free(authopts);
1.68 djm 304: sshkey_free(key);
1.112 ! djm 305: sshkey_free(hostkey);
1.64 markus 306: free(userstyle);
1.36 djm 307: free(pkalg);
308: free(pkblob);
1.73 djm 309: free(key_s);
310: free(ca_s);
1.83 djm 311: free(sig);
1.95 djm 312: sshkey_sig_details_free(sig_details);
1.1 markus 313: return authenticated;
314: }
315:
1.24 djm 316: static int
1.40 djm 317: match_principals_option(const char *principal_list, struct sshkey_cert *cert)
1.24 djm 318: {
319: char *result;
320: u_int i;
321:
322: /* XXX percent_expand() sequences for authorized_principals? */
323:
324: for (i = 0; i < cert->nprincipals; i++) {
325: if ((result = match_list(cert->principals[i],
326: principal_list, NULL)) != NULL) {
327: debug3("matched principal from key options \"%.100s\"",
328: result);
1.36 djm 329: free(result);
1.24 djm 330: return 1;
331: }
332: }
333: return 0;
334: }
335:
1.77 djm 336: /*
337: * Process a single authorized_principals format line. Returns 0 and sets
338: * authoptsp is principal is authorised, -1 otherwise. "loc" is used as a
339: * log preamble for file/line information.
340: */
1.24 djm 341: static int
1.77 djm 342: check_principals_line(struct ssh *ssh, char *cp, const struct sshkey_cert *cert,
343: const char *loc, struct sshauthopt **authoptsp)
1.24 djm 344: {
1.77 djm 345: u_int i, found = 0;
346: char *ep, *line_opts;
347: const char *reason = NULL;
348: struct sshauthopt *opts = NULL;
349:
350: if (authoptsp != NULL)
351: *authoptsp = NULL;
352:
353: /* Trim trailing whitespace. */
354: ep = cp + strlen(cp) - 1;
355: while (ep > cp && (*ep == '\n' || *ep == ' ' || *ep == '\t'))
356: *ep-- = '\0';
357:
358: /*
359: * If the line has internal whitespace then assume it has
360: * key options.
361: */
362: line_opts = NULL;
363: if ((ep = strrchr(cp, ' ')) != NULL ||
364: (ep = strrchr(cp, '\t')) != NULL) {
365: for (; *ep == ' ' || *ep == '\t'; ep++)
366: ;
367: line_opts = cp;
368: cp = ep;
369: }
370: if ((opts = sshauthopt_parse(line_opts, &reason)) == NULL) {
371: debug("%s: bad principals options: %s", loc, reason);
372: auth_debug_add("%s: bad principals options: %s", loc, reason);
373: return -1;
374: }
375: /* Check principals in cert against those on line */
376: for (i = 0; i < cert->nprincipals; i++) {
377: if (strcmp(cp, cert->principals[i]) != 0)
378: continue;
379: debug3("%s: matched principal \"%.100s\"",
380: loc, cert->principals[i]);
381: found = 1;
382: }
383: if (found && authoptsp != NULL) {
384: *authoptsp = opts;
385: opts = NULL;
386: }
387: sshauthopt_free(opts);
388: return found ? 0 : -1;
389: }
390:
391: static int
392: process_principals(struct ssh *ssh, FILE *f, const char *file,
393: const struct sshkey_cert *cert, struct sshauthopt **authoptsp)
394: {
1.79 markus 395: char loc[256], *line = NULL, *cp, *ep;
396: size_t linesize = 0;
1.110 djm 397: u_long linenum = 0, nonblank = 0;
1.77 djm 398: u_int found_principal = 0;
399:
400: if (authoptsp != NULL)
401: *authoptsp = NULL;
1.24 djm 402:
1.79 markus 403: while (getline(&line, &linesize, f) != -1) {
404: linenum++;
1.62 djm 405: /* Always consume entire input */
406: if (found_principal)
407: continue;
1.77 djm 408:
1.26 djm 409: /* Skip leading whitespace. */
1.24 djm 410: for (cp = line; *cp == ' ' || *cp == '\t'; cp++)
411: ;
1.26 djm 412: /* Skip blank and comment lines. */
413: if ((ep = strchr(cp, '#')) != NULL)
414: *ep = '\0';
415: if (!*cp || *cp == '\n')
1.24 djm 416: continue;
1.77 djm 417:
1.110 djm 418: nonblank++;
1.77 djm 419: snprintf(loc, sizeof(loc), "%.200s:%lu", file, linenum);
420: if (check_principals_line(ssh, cp, cert, loc, authoptsp) == 0)
421: found_principal = 1;
1.24 djm 422: }
1.110 djm 423: debug2_f("%s: processed %lu/%lu lines", file, nonblank, linenum);
1.79 markus 424: free(line);
1.62 djm 425: return found_principal;
1.51 djm 426: }
427:
1.77 djm 428: /* XXX remove pw args here and elsewhere once ssh->authctxt is guaranteed */
429:
1.51 djm 430: static int
1.77 djm 431: match_principals_file(struct ssh *ssh, struct passwd *pw, char *file,
432: struct sshkey_cert *cert, struct sshauthopt **authoptsp)
1.51 djm 433: {
434: FILE *f;
435: int success;
436:
1.77 djm 437: if (authoptsp != NULL)
438: *authoptsp = NULL;
439:
1.51 djm 440: temporarily_use_uid(pw);
441: debug("trying authorized principals file %s", file);
442: if ((f = auth_openprincipals(file, pw, options.strict_modes)) == NULL) {
443: restore_uid();
444: return 0;
445: }
1.77 djm 446: success = process_principals(ssh, f, file, cert, authoptsp);
1.24 djm 447: fclose(f);
448: restore_uid();
1.51 djm 449: return success;
1.31 djm 450: }
1.24 djm 451:
1.31 djm 452: /*
1.51 djm 453: * Checks whether principal is allowed in output of command.
454: * returns 1 if the principal is allowed or 0 otherwise.
455: */
456: static int
1.77 djm 457: match_principals_command(struct ssh *ssh, struct passwd *user_pw,
458: const struct sshkey *key, struct sshauthopt **authoptsp)
1.51 djm 459: {
1.77 djm 460: struct passwd *runas_pw = NULL;
1.56 djm 461: const struct sshkey_cert *cert = key->cert;
1.51 djm 462: FILE *f = NULL;
1.56 djm 463: int r, ok, found_principal = 0;
1.51 djm 464: int i, ac = 0, uid_swapped = 0;
465: pid_t pid;
466: char *tmp, *username = NULL, *command = NULL, **av = NULL;
1.56 djm 467: char *ca_fp = NULL, *key_fp = NULL, *catext = NULL, *keytext = NULL;
1.88 djm 468: char serial_s[32], uidstr[32];
1.51 djm 469: void (*osigchld)(int);
470:
1.77 djm 471: if (authoptsp != NULL)
472: *authoptsp = NULL;
1.51 djm 473: if (options.authorized_principals_command == NULL)
474: return 0;
475: if (options.authorized_principals_command_user == NULL) {
476: error("No user for AuthorizedPrincipalsCommand specified, "
477: "skipping");
478: return 0;
479: }
480:
481: /*
482: * NB. all returns later this function should go via "out" to
483: * ensure the original SIGCHLD handler is restored properly.
484: */
1.98 dtucker 485: osigchld = ssh_signal(SIGCHLD, SIG_DFL);
1.51 djm 486:
487: /* Prepare and verify the user for the command */
488: username = percent_expand(options.authorized_principals_command_user,
489: "u", user_pw->pw_name, (char *)NULL);
1.77 djm 490: runas_pw = getpwnam(username);
491: if (runas_pw == NULL) {
1.51 djm 492: error("AuthorizedPrincipalsCommandUser \"%s\" not found: %s",
493: username, strerror(errno));
494: goto out;
495: }
496:
497: /* Turn the command into an argument vector */
1.108 djm 498: if (argv_split(options.authorized_principals_command,
499: &ac, &av, 0) != 0) {
1.51 djm 500: error("AuthorizedPrincipalsCommand \"%s\" contains "
1.90 djm 501: "invalid quotes", options.authorized_principals_command);
1.51 djm 502: goto out;
503: }
504: if (ac == 0) {
505: error("AuthorizedPrincipalsCommand \"%s\" yielded no arguments",
1.90 djm 506: options.authorized_principals_command);
1.51 djm 507: goto out;
508: }
1.56 djm 509: if ((ca_fp = sshkey_fingerprint(cert->signature_key,
510: options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) {
1.101 djm 511: error_f("sshkey_fingerprint failed");
1.56 djm 512: goto out;
513: }
1.57 djm 514: if ((key_fp = sshkey_fingerprint(key,
1.56 djm 515: options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) {
1.101 djm 516: error_f("sshkey_fingerprint failed");
1.56 djm 517: goto out;
518: }
519: if ((r = sshkey_to_base64(cert->signature_key, &catext)) != 0) {
1.101 djm 520: error_fr(r, "sshkey_to_base64 failed");
1.56 djm 521: goto out;
522: }
523: if ((r = sshkey_to_base64(key, &keytext)) != 0) {
1.101 djm 524: error_fr(r, "sshkey_to_base64 failed");
1.56 djm 525: goto out;
526: }
1.59 djm 527: snprintf(serial_s, sizeof(serial_s), "%llu",
528: (unsigned long long)cert->serial);
1.78 djm 529: snprintf(uidstr, sizeof(uidstr), "%llu",
530: (unsigned long long)user_pw->pw_uid);
1.51 djm 531: for (i = 1; i < ac; i++) {
532: tmp = percent_expand(av[i],
1.78 djm 533: "U", uidstr,
1.51 djm 534: "u", user_pw->pw_name,
535: "h", user_pw->pw_dir,
1.56 djm 536: "t", sshkey_ssh_name(key),
537: "T", sshkey_ssh_name(cert->signature_key),
538: "f", key_fp,
539: "F", ca_fp,
540: "k", keytext,
541: "K", catext,
1.58 djm 542: "i", cert->key_id,
543: "s", serial_s,
1.51 djm 544: (char *)NULL);
545: if (tmp == NULL)
1.101 djm 546: fatal_f("percent_expand failed");
1.51 djm 547: free(av[i]);
548: av[i] = tmp;
549: }
550: /* Prepare a printable command for logs, etc. */
1.69 djm 551: command = argv_assemble(ac, av);
1.51 djm 552:
1.103 djm 553: if ((pid = subprocess("AuthorizedPrincipalsCommand", command,
1.69 djm 554: ac, av, &f,
1.103 djm 555: SSH_SUBPROCESS_STDOUT_CAPTURE|SSH_SUBPROCESS_STDERR_DISCARD,
556: runas_pw, temporarily_use_uid, restore_uid)) == 0)
1.51 djm 557: goto out;
558:
559: uid_swapped = 1;
1.77 djm 560: temporarily_use_uid(runas_pw);
1.51 djm 561:
1.77 djm 562: ok = process_principals(ssh, f, "(command)", cert, authoptsp);
1.51 djm 563:
1.61 djm 564: fclose(f);
565: f = NULL;
566:
1.70 djm 567: if (exited_cleanly(pid, "AuthorizedPrincipalsCommand", command, 0) != 0)
1.51 djm 568: goto out;
569:
570: /* Read completed successfully */
571: found_principal = ok;
572: out:
573: if (f != NULL)
574: fclose(f);
1.98 dtucker 575: ssh_signal(SIGCHLD, osigchld);
1.51 djm 576: for (i = 0; i < ac; i++)
577: free(av[i]);
578: free(av);
579: if (uid_swapped)
580: restore_uid();
581: free(command);
582: free(username);
1.56 djm 583: free(ca_fp);
584: free(key_fp);
585: free(catext);
586: free(keytext);
1.51 djm 587: return found_principal;
1.77 djm 588: }
589:
590: /*
591: * Check a single line of an authorized_keys-format file. Returns 0 if key
592: * matches, -1 otherwise. Will return key/cert options via *authoptsp
593: * on success. "loc" is used as file/line location in log messages.
594: */
595: static int
596: check_authkey_line(struct ssh *ssh, struct passwd *pw, struct sshkey *key,
597: char *cp, const char *loc, struct sshauthopt **authoptsp)
598: {
599: int want_keytype = sshkey_is_cert(key) ? KEY_UNSPEC : key->type;
600: struct sshkey *found = NULL;
601: struct sshauthopt *keyopts = NULL, *certopts = NULL, *finalopts = NULL;
602: char *key_options = NULL, *fp = NULL;
603: const char *reason = NULL;
604: int ret = -1;
605:
606: if (authoptsp != NULL)
607: *authoptsp = NULL;
608:
609: if ((found = sshkey_new(want_keytype)) == NULL) {
1.101 djm 610: debug3_f("keytype %d failed", want_keytype);
1.77 djm 611: goto out;
612: }
613:
614: /* XXX djm: peek at key type in line and skip if unwanted */
615:
616: if (sshkey_read(found, &cp) != 0) {
617: /* no key? check for options */
618: debug2("%s: check options: '%s'", loc, cp);
619: key_options = cp;
1.93 djm 620: if (sshkey_advance_past_options(&cp) != 0) {
1.77 djm 621: reason = "invalid key option string";
622: goto fail_reason;
623: }
624: skip_space(&cp);
625: if (sshkey_read(found, &cp) != 0) {
626: /* still no key? advance to next line*/
627: debug2("%s: advance: '%s'", loc, cp);
628: goto out;
629: }
630: }
631: /* Parse key options now; we need to know if this is a CA key */
632: if ((keyopts = sshauthopt_parse(key_options, &reason)) == NULL) {
633: debug("%s: bad key options: %s", loc, reason);
634: auth_debug_add("%s: bad key options: %s", loc, reason);
635: goto out;
636: }
637: /* Ignore keys that don't match or incorrectly marked as CAs */
638: if (sshkey_is_cert(key)) {
639: /* Certificate; check signature key against CA */
640: if (!sshkey_equal(found, key->cert->signature_key) ||
641: !keyopts->cert_authority)
642: goto out;
643: } else {
644: /* Plain key: check it against key found in file */
645: if (!sshkey_equal(found, key) || keyopts->cert_authority)
646: goto out;
647: }
648:
649: /* We have a candidate key, perform authorisation checks */
650: if ((fp = sshkey_fingerprint(found,
651: options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL)
1.101 djm 652: fatal_f("fingerprint failed");
1.77 djm 653:
654: debug("%s: matching %s found: %s %s", loc,
655: sshkey_is_cert(key) ? "CA" : "key", sshkey_type(found), fp);
656:
657: if (auth_authorise_keyopts(ssh, pw, keyopts,
658: sshkey_is_cert(key), loc) != 0) {
659: reason = "Refused by key options";
660: goto fail_reason;
661: }
662: /* That's all we need for plain keys. */
663: if (!sshkey_is_cert(key)) {
664: verbose("Accepted key %s %s found at %s",
665: sshkey_type(found), fp, loc);
666: finalopts = keyopts;
667: keyopts = NULL;
668: goto success;
669: }
670:
671: /*
672: * Additional authorisation for certificates.
673: */
674:
675: /* Parse and check options present in certificate */
676: if ((certopts = sshauthopt_from_cert(key)) == NULL) {
677: reason = "Invalid certificate options";
678: goto fail_reason;
679: }
680: if (auth_authorise_keyopts(ssh, pw, certopts, 0, loc) != 0) {
681: reason = "Refused by certificate options";
682: goto fail_reason;
683: }
684: if ((finalopts = sshauthopt_merge(keyopts, certopts, &reason)) == NULL)
685: goto fail_reason;
686:
687: /*
688: * If the user has specified a list of principals as
689: * a key option, then prefer that list to matching
690: * their username in the certificate principals list.
691: */
692: if (keyopts->cert_principals != NULL &&
693: !match_principals_option(keyopts->cert_principals, key->cert)) {
694: reason = "Certificate does not contain an authorized principal";
695: goto fail_reason;
696: }
1.109 djm 697: if (sshkey_cert_check_authority_now(key, 0, 0, 0,
1.107 djm 698: keyopts->cert_principals == NULL ? pw->pw_name : NULL,
699: &reason) != 0)
1.77 djm 700: goto fail_reason;
701:
702: verbose("Accepted certificate ID \"%s\" (serial %llu) "
703: "signed by CA %s %s found at %s",
704: key->cert->key_id,
705: (unsigned long long)key->cert->serial,
706: sshkey_type(found), fp, loc);
707:
708: success:
709: if (finalopts == NULL)
1.101 djm 710: fatal_f("internal error: missing options");
1.77 djm 711: if (authoptsp != NULL) {
712: *authoptsp = finalopts;
713: finalopts = NULL;
714: }
715: /* success */
716: ret = 0;
717: goto out;
718:
719: fail_reason:
720: error("%s", reason);
721: auth_debug_add("%s", reason);
722: out:
723: free(fp);
724: sshauthopt_free(keyopts);
725: sshauthopt_free(certopts);
726: sshauthopt_free(finalopts);
727: sshkey_free(found);
728: return ret;
729: }
730:
1.51 djm 731: /*
1.31 djm 732: * Checks whether key is allowed in authorized_keys-format file,
733: * returns 1 if the key is allowed or 0 otherwise.
734: */
1.1 markus 735: static int
1.77 djm 736: check_authkeys_file(struct ssh *ssh, struct passwd *pw, FILE *f,
737: char *file, struct sshkey *key, struct sshauthopt **authoptsp)
1.1 markus 738: {
1.79 markus 739: char *cp, *line = NULL, loc[256];
740: size_t linesize = 0;
1.18 dtucker 741: int found_key = 0;
1.110 djm 742: u_long linenum = 0, nonblank = 0;
1.77 djm 743:
744: if (authoptsp != NULL)
745: *authoptsp = NULL;
1.1 markus 746:
1.79 markus 747: while (getline(&line, &linesize, f) != -1) {
748: linenum++;
1.71 djm 749: /* Always consume entire file */
1.62 djm 750: if (found_key)
751: continue;
1.20 djm 752:
1.1 markus 753: /* Skip leading whitespace, empty and comment lines. */
1.77 djm 754: cp = line;
755: skip_space(&cp);
1.1 markus 756: if (!*cp || *cp == '\n' || *cp == '#')
757: continue;
1.110 djm 758:
759: nonblank++;
1.77 djm 760: snprintf(loc, sizeof(loc), "%.200s:%lu", file, linenum);
761: if (check_authkey_line(ssh, pw, key, cp, loc, authoptsp) == 0)
1.20 djm 762: found_key = 1;
1.1 markus 763: }
1.79 markus 764: free(line);
1.110 djm 765: debug2_f("%s: processed %lu/%lu lines", file, nonblank, linenum);
1.1 markus 766: return found_key;
767: }
768:
1.21 djm 769: /* Authenticate a certificate key against TrustedUserCAKeys */
770: static int
1.77 djm 771: user_cert_trusted_ca(struct ssh *ssh, struct passwd *pw, struct sshkey *key,
772: struct sshauthopt **authoptsp)
1.21 djm 773: {
1.24 djm 774: char *ca_fp, *principals_file = NULL;
1.21 djm 775: const char *reason;
1.77 djm 776: struct sshauthopt *principals_opts = NULL, *cert_opts = NULL;
777: struct sshauthopt *final_opts = NULL;
1.64 markus 778: int r, ret = 0, found_principal = 0, use_authorized_principals;
1.21 djm 779:
1.77 djm 780: if (authoptsp != NULL)
781: *authoptsp = NULL;
782:
1.64 markus 783: if (!sshkey_is_cert(key) || options.trusted_user_ca_keys == NULL)
1.21 djm 784: return 0;
785:
1.46 djm 786: if ((ca_fp = sshkey_fingerprint(key->cert->signature_key,
787: options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL)
788: return 0;
1.21 djm 789:
1.64 markus 790: if ((r = sshkey_in_file(key->cert->signature_key,
791: options.trusted_user_ca_keys, 1, 0)) != 0) {
1.101 djm 792: debug2_fr(r, "CA %s %s is not listed in %s",
1.64 markus 793: sshkey_type(key->cert->signature_key), ca_fp,
1.101 djm 794: options.trusted_user_ca_keys);
1.21 djm 795: goto out;
796: }
1.24 djm 797: /*
798: * If AuthorizedPrincipals is in use, then compare the certificate
799: * principals against the names in that file rather than matching
800: * against the username.
801: */
802: if ((principals_file = authorized_principals_file(pw)) != NULL) {
1.77 djm 803: if (match_principals_file(ssh, pw, principals_file,
804: key->cert, &principals_opts))
1.51 djm 805: found_principal = 1;
806: }
807: /* Try querying command if specified */
1.77 djm 808: if (!found_principal && match_principals_command(ssh, pw, key,
809: &principals_opts))
1.51 djm 810: found_principal = 1;
1.53 jsing 811: /* If principals file or command is specified, then require a match */
812: use_authorized_principals = principals_file != NULL ||
1.107 djm 813: options.authorized_principals_command != NULL;
1.53 jsing 814: if (!found_principal && use_authorized_principals) {
1.51 djm 815: reason = "Certificate does not contain an authorized principal";
1.77 djm 816: goto fail_reason;
1.21 djm 817: }
1.77 djm 818: if (use_authorized_principals && principals_opts == NULL)
1.101 djm 819: fatal_f("internal error: missing principals_opts");
1.109 djm 820: if (sshkey_cert_check_authority_now(key, 0, 1, 0,
1.53 jsing 821: use_authorized_principals ? NULL : pw->pw_name, &reason) != 0)
1.24 djm 822: goto fail_reason;
1.77 djm 823:
824: /* Check authority from options in key and from principals file/cmd */
825: if ((cert_opts = sshauthopt_from_cert(key)) == NULL) {
826: reason = "Invalid certificate options";
827: goto fail_reason;
828: }
829: if (auth_authorise_keyopts(ssh, pw, cert_opts, 0, "cert") != 0) {
830: reason = "Refused by certificate options";
1.60 djm 831: goto fail_reason;
1.77 djm 832: }
833: if (principals_opts == NULL) {
834: final_opts = cert_opts;
835: cert_opts = NULL;
836: } else {
837: if (auth_authorise_keyopts(ssh, pw, principals_opts, 0,
838: "principals") != 0) {
839: reason = "Refused by certificate principals options";
840: goto fail_reason;
841: }
842: if ((final_opts = sshauthopt_merge(principals_opts,
843: cert_opts, &reason)) == NULL) {
844: fail_reason:
845: error("%s", reason);
846: auth_debug_add("%s", reason);
847: goto out;
848: }
849: }
1.21 djm 850:
1.77 djm 851: /* Success */
1.54 djm 852: verbose("Accepted certificate ID \"%s\" (serial %llu) signed by "
853: "%s CA %s via %s", key->cert->key_id,
854: (unsigned long long)key->cert->serial,
1.64 markus 855: sshkey_type(key->cert->signature_key), ca_fp,
1.22 djm 856: options.trusted_user_ca_keys);
1.77 djm 857: if (authoptsp != NULL) {
858: *authoptsp = final_opts;
859: final_opts = NULL;
860: }
1.21 djm 861: ret = 1;
862: out:
1.77 djm 863: sshauthopt_free(principals_opts);
864: sshauthopt_free(cert_opts);
865: sshauthopt_free(final_opts);
1.36 djm 866: free(principals_file);
867: free(ca_fp);
1.21 djm 868: return ret;
869: }
870:
1.31 djm 871: /*
872: * Checks whether key is allowed in file.
873: * returns 1 if the key is allowed or 0 otherwise.
874: */
875: static int
1.77 djm 876: user_key_allowed2(struct ssh *ssh, struct passwd *pw, struct sshkey *key,
877: char *file, struct sshauthopt **authoptsp)
1.31 djm 878: {
879: FILE *f;
880: int found_key = 0;
881:
1.77 djm 882: if (authoptsp != NULL)
883: *authoptsp = NULL;
884:
1.31 djm 885: /* Temporarily use the user's uid. */
886: temporarily_use_uid(pw);
887:
888: debug("trying public key file %s", file);
889: if ((f = auth_openkeyfile(file, pw, options.strict_modes)) != NULL) {
1.77 djm 890: found_key = check_authkeys_file(ssh, pw, f, file,
891: key, authoptsp);
1.31 djm 892: fclose(f);
893: }
894:
895: restore_uid();
896: return found_key;
897: }
898:
899: /*
900: * Checks whether key is allowed in output of command.
901: * returns 1 if the key is allowed or 0 otherwise.
902: */
903: static int
1.77 djm 904: user_key_command_allowed2(struct ssh *ssh, struct passwd *user_pw,
905: struct sshkey *key, struct sshauthopt **authoptsp)
1.31 djm 906: {
1.77 djm 907: struct passwd *runas_pw = NULL;
1.50 djm 908: FILE *f = NULL;
909: int r, ok, found_key = 0;
910: int i, uid_swapped = 0, ac = 0;
1.31 djm 911: pid_t pid;
1.50 djm 912: char *username = NULL, *key_fp = NULL, *keytext = NULL;
1.78 djm 913: char uidstr[32], *tmp, *command = NULL, **av = NULL;
1.50 djm 914: void (*osigchld)(int);
1.31 djm 915:
1.77 djm 916: if (authoptsp != NULL)
917: *authoptsp = NULL;
1.50 djm 918: if (options.authorized_keys_command == NULL)
1.31 djm 919: return 0;
1.32 djm 920: if (options.authorized_keys_command_user == NULL) {
921: error("No user for AuthorizedKeysCommand specified, skipping");
922: return 0;
923: }
924:
1.50 djm 925: /*
926: * NB. all returns later this function should go via "out" to
927: * ensure the original SIGCHLD handler is restored properly.
928: */
1.98 dtucker 929: osigchld = ssh_signal(SIGCHLD, SIG_DFL);
1.50 djm 930:
931: /* Prepare and verify the user for the command */
1.32 djm 932: username = percent_expand(options.authorized_keys_command_user,
933: "u", user_pw->pw_name, (char *)NULL);
1.77 djm 934: runas_pw = getpwnam(username);
935: if (runas_pw == NULL) {
1.34 djm 936: error("AuthorizedKeysCommandUser \"%s\" not found: %s",
937: username, strerror(errno));
1.50 djm 938: goto out;
1.31 djm 939: }
940:
1.50 djm 941: /* Prepare AuthorizedKeysCommand */
942: if ((key_fp = sshkey_fingerprint(key, options.fingerprint_hash,
943: SSH_FP_DEFAULT)) == NULL) {
1.101 djm 944: error_f("sshkey_fingerprint failed");
1.31 djm 945: goto out;
946: }
1.50 djm 947: if ((r = sshkey_to_base64(key, &keytext)) != 0) {
1.101 djm 948: error_fr(r, "sshkey_to_base64 failed");
1.31 djm 949: goto out;
950: }
951:
1.50 djm 952: /* Turn the command into an argument vector */
1.108 djm 953: if (argv_split(options.authorized_keys_command, &ac, &av, 0) != 0) {
1.50 djm 954: error("AuthorizedKeysCommand \"%s\" contains invalid quotes",
1.102 djm 955: options.authorized_keys_command);
1.50 djm 956: goto out;
957: }
958: if (ac == 0) {
959: error("AuthorizedKeysCommand \"%s\" yielded no arguments",
1.102 djm 960: options.authorized_keys_command);
1.31 djm 961: goto out;
962: }
1.78 djm 963: snprintf(uidstr, sizeof(uidstr), "%llu",
964: (unsigned long long)user_pw->pw_uid);
1.50 djm 965: for (i = 1; i < ac; i++) {
966: tmp = percent_expand(av[i],
1.78 djm 967: "U", uidstr,
1.50 djm 968: "u", user_pw->pw_name,
969: "h", user_pw->pw_dir,
970: "t", sshkey_ssh_name(key),
971: "f", key_fp,
972: "k", keytext,
973: (char *)NULL);
974: if (tmp == NULL)
1.101 djm 975: fatal_f("percent_expand failed");
1.50 djm 976: free(av[i]);
977: av[i] = tmp;
978: }
979: /* Prepare a printable command for logs, etc. */
1.69 djm 980: command = argv_assemble(ac, av);
1.31 djm 981:
982: /*
1.50 djm 983: * If AuthorizedKeysCommand was run without arguments
984: * then fall back to the old behaviour of passing the
985: * target username as a single argument.
1.31 djm 986: */
1.50 djm 987: if (ac == 1) {
988: av = xreallocarray(av, ac + 2, sizeof(*av));
989: av[1] = xstrdup(user_pw->pw_name);
990: av[2] = NULL;
991: /* Fix up command too, since it is used in log messages */
992: free(command);
993: xasprintf(&command, "%s %s", av[0], av[1]);
994: }
1.31 djm 995:
1.103 djm 996: if ((pid = subprocess("AuthorizedKeysCommand", command,
1.69 djm 997: ac, av, &f,
1.103 djm 998: SSH_SUBPROCESS_STDOUT_CAPTURE|SSH_SUBPROCESS_STDERR_DISCARD,
999: runas_pw, temporarily_use_uid, restore_uid)) == 0)
1.50 djm 1000: goto out;
1.31 djm 1001:
1.50 djm 1002: uid_swapped = 1;
1.77 djm 1003: temporarily_use_uid(runas_pw);
1.31 djm 1004:
1.77 djm 1005: ok = check_authkeys_file(ssh, user_pw, f,
1006: options.authorized_keys_command, key, authoptsp);
1.61 djm 1007:
1008: fclose(f);
1009: f = NULL;
1.31 djm 1010:
1.70 djm 1011: if (exited_cleanly(pid, "AuthorizedKeysCommand", command, 0) != 0)
1.31 djm 1012: goto out;
1.50 djm 1013:
1014: /* Read completed successfully */
1.31 djm 1015: found_key = ok;
1016: out:
1.50 djm 1017: if (f != NULL)
1018: fclose(f);
1.98 dtucker 1019: ssh_signal(SIGCHLD, osigchld);
1.50 djm 1020: for (i = 0; i < ac; i++)
1021: free(av[i]);
1022: free(av);
1023: if (uid_swapped)
1024: restore_uid();
1025: free(command);
1026: free(username);
1027: free(key_fp);
1028: free(keytext);
1.31 djm 1029: return found_key;
1030: }
1031:
1032: /*
1033: * Check whether key authenticates and authorises the user.
1034: */
1.1 markus 1035: int
1.77 djm 1036: user_key_allowed(struct ssh *ssh, struct passwd *pw, struct sshkey *key,
1037: int auth_attempt, struct sshauthopt **authoptsp)
1.1 markus 1038: {
1.89 djm 1039: u_int success = 0, i;
1.1 markus 1040: char *file;
1.77 djm 1041: struct sshauthopt *opts = NULL;
1.89 djm 1042:
1.77 djm 1043: if (authoptsp != NULL)
1044: *authoptsp = NULL;
1.21 djm 1045:
1046: if (auth_key_is_revoked(key))
1047: return 0;
1.64 markus 1048: if (sshkey_is_cert(key) &&
1049: auth_key_is_revoked(key->cert->signature_key))
1.21 djm 1050: return 0;
1051:
1.89 djm 1052: for (i = 0; !success && i < options.num_authkeys_files; i++) {
1053: if (strcasecmp(options.authorized_keys_files[i], "none") == 0)
1054: continue;
1055: file = expand_authorized_keys(
1056: options.authorized_keys_files[i], pw);
1057: success = user_key_allowed2(ssh, pw, key, file, &opts);
1058: free(file);
1059: if (!success) {
1060: sshauthopt_free(opts);
1061: opts = NULL;
1062: }
1063: }
1064: if (success)
1065: goto out;
1066:
1.77 djm 1067: if ((success = user_cert_trusted_ca(ssh, pw, key, &opts)) != 0)
1068: goto out;
1069: sshauthopt_free(opts);
1070: opts = NULL;
1071:
1072: if ((success = user_key_command_allowed2(ssh, pw, key, &opts)) != 0)
1073: goto out;
1074: sshauthopt_free(opts);
1075: opts = NULL;
1.1 markus 1076:
1.77 djm 1077: out:
1078: if (success && authoptsp != NULL) {
1079: *authoptsp = opts;
1080: opts = NULL;
1081: }
1082: sshauthopt_free(opts);
1.1 markus 1083: return success;
1084: }
1.2 markus 1085:
1086: Authmethod method_pubkey = {
1087: "publickey",
1.112 ! djm 1088: "publickey-hostbound-v00@openssh.com",
1.2 markus 1089: userauth_pubkey,
1090: &options.pubkey_authentication
1091: };
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