Annotation of src/usr.bin/ssh/auth2-pubkey.c, Revision 1.30
1.30 ! djm 1: /* $OpenBSD: auth2-pubkey.c,v 1.29 2011/05/23 03:30:07 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:
1.16 djm 30: #include <fcntl.h>
1.13 stevesk 31: #include <pwd.h>
1.14 stevesk 32: #include <stdio.h>
1.15 deraadt 33: #include <stdarg.h>
1.20 djm 34: #include <string.h>
35: #include <time.h>
1.17 dtucker 36: #include <unistd.h>
1.1 markus 37:
1.15 deraadt 38: #include "xmalloc.h"
1.8 dtucker 39: #include "ssh.h"
1.1 markus 40: #include "ssh2.h"
41: #include "packet.h"
42: #include "buffer.h"
43: #include "log.h"
44: #include "servconf.h"
45: #include "compat.h"
1.15 deraadt 46: #include "key.h"
47: #include "hostfile.h"
1.1 markus 48: #include "auth.h"
49: #include "pathnames.h"
50: #include "uidswap.h"
51: #include "auth-options.h"
52: #include "canohost.h"
1.15 deraadt 53: #ifdef GSSAPI
54: #include "ssh-gss.h"
55: #endif
1.1 markus 56: #include "monitor_wrap.h"
1.9 dtucker 57: #include "misc.h"
1.21 djm 58: #include "authfile.h"
1.24 djm 59: #include "match.h"
1.1 markus 60:
61: /* import */
62: extern ServerOptions options;
63: extern u_char *session_id2;
1.4 markus 64: extern u_int session_id2_len;
1.1 markus 65:
1.2 markus 66: static int
1.1 markus 67: userauth_pubkey(Authctxt *authctxt)
68: {
69: Buffer b;
70: Key *key = NULL;
71: char *pkalg;
72: u_char *pkblob, *sig;
73: u_int alen, blen, slen;
74: int have_sig, pktype;
75: int authenticated = 0;
76:
77: if (!authctxt->valid) {
78: debug2("userauth_pubkey: disabled because of invalid user");
79: return 0;
80: }
81: have_sig = packet_get_char();
82: if (datafellows & SSH_BUG_PKAUTH) {
83: debug2("userauth_pubkey: SSH_BUG_PKAUTH");
84: /* no explicit pkalg given */
85: pkblob = packet_get_string(&blen);
86: buffer_init(&b);
87: buffer_append(&b, pkblob, blen);
88: /* so we have to extract the pkalg from the pkblob */
89: pkalg = buffer_get_string(&b, &alen);
90: buffer_free(&b);
91: } else {
92: pkalg = packet_get_string(&alen);
93: pkblob = packet_get_string(&blen);
94: }
95: pktype = key_type_from_name(pkalg);
96: if (pktype == KEY_UNSPEC) {
97: /* this is perfectly legal */
1.3 itojun 98: logit("userauth_pubkey: unsupported public key algorithm: %s",
1.1 markus 99: pkalg);
100: goto done;
101: }
102: key = key_from_blob(pkblob, blen);
103: if (key == NULL) {
104: error("userauth_pubkey: cannot decode key: %s", pkalg);
105: goto done;
106: }
107: if (key->type != pktype) {
108: error("userauth_pubkey: type mismatch for decoded key "
109: "(received %d, expected %d)", key->type, pktype);
110: goto done;
111: }
112: if (have_sig) {
113: sig = packet_get_string(&slen);
114: packet_check_eom();
115: buffer_init(&b);
116: if (datafellows & SSH_OLD_SESSIONID) {
117: buffer_append(&b, session_id2, session_id2_len);
118: } else {
119: buffer_put_string(&b, session_id2, session_id2_len);
120: }
121: /* reconstruct packet */
122: buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
123: buffer_put_cstring(&b, authctxt->user);
124: buffer_put_cstring(&b,
125: datafellows & SSH_BUG_PKSERVICE ?
126: "ssh-userauth" :
127: authctxt->service);
128: if (datafellows & SSH_BUG_PKAUTH) {
129: buffer_put_char(&b, have_sig);
130: } else {
131: buffer_put_cstring(&b, "publickey");
132: buffer_put_char(&b, have_sig);
133: buffer_put_cstring(&b, pkalg);
134: }
135: buffer_put_string(&b, pkblob, blen);
136: #ifdef DEBUG_PK
137: buffer_dump(&b);
138: #endif
139: /* test for correct signature */
140: authenticated = 0;
141: if (PRIVSEP(user_key_allowed(authctxt->pw, key)) &&
142: PRIVSEP(key_verify(key, sig, slen, buffer_ptr(&b),
1.6 markus 143: buffer_len(&b))) == 1)
1.1 markus 144: authenticated = 1;
1.6 markus 145: buffer_free(&b);
1.1 markus 146: xfree(sig);
147: } else {
148: debug("test whether pkalg/pkblob are acceptable");
149: packet_check_eom();
150:
151: /* XXX fake reply and always send PK_OK ? */
152: /*
153: * XXX this allows testing whether a user is allowed
154: * to login: if you happen to have a valid pubkey this
155: * message is sent. the message is NEVER sent at all
156: * if a user is not allowed to login. is this an
157: * issue? -markus
158: */
159: if (PRIVSEP(user_key_allowed(authctxt->pw, key))) {
160: packet_start(SSH2_MSG_USERAUTH_PK_OK);
161: packet_put_string(pkalg, alen);
162: packet_put_string(pkblob, blen);
163: packet_send();
164: packet_write_wait();
165: authctxt->postponed = 1;
166: }
167: }
168: if (authenticated != 1)
169: auth_clear_options();
170: done:
171: debug2("userauth_pubkey: authenticated %d pkalg %s", authenticated, pkalg);
172: if (key != NULL)
173: key_free(key);
174: xfree(pkalg);
175: xfree(pkblob);
176: return authenticated;
177: }
178:
1.24 djm 179: static int
180: match_principals_option(const char *principal_list, struct KeyCert *cert)
181: {
182: char *result;
183: u_int i;
184:
185: /* XXX percent_expand() sequences for authorized_principals? */
186:
187: for (i = 0; i < cert->nprincipals; i++) {
188: if ((result = match_list(cert->principals[i],
189: principal_list, NULL)) != NULL) {
190: debug3("matched principal from key options \"%.100s\"",
191: result);
192: xfree(result);
193: return 1;
194: }
195: }
196: return 0;
197: }
198:
199: static int
1.26 djm 200: match_principals_file(char *file, struct passwd *pw, struct KeyCert *cert)
1.24 djm 201: {
202: FILE *f;
1.26 djm 203: char line[SSH_MAX_PUBKEY_BYTES], *cp, *ep, *line_opts;
1.24 djm 204: u_long linenum = 0;
205: u_int i;
206:
207: temporarily_use_uid(pw);
208: debug("trying authorized principals file %s", file);
209: if ((f = auth_openprincipals(file, pw, options.strict_modes)) == NULL) {
210: restore_uid();
211: return 0;
212: }
213: while (read_keyfile_line(f, file, line, sizeof(line), &linenum) != -1) {
1.26 djm 214: /* Skip leading whitespace. */
1.24 djm 215: for (cp = line; *cp == ' ' || *cp == '\t'; cp++)
216: ;
1.26 djm 217: /* Skip blank and comment lines. */
218: if ((ep = strchr(cp, '#')) != NULL)
219: *ep = '\0';
220: if (!*cp || *cp == '\n')
1.24 djm 221: continue;
1.26 djm 222: /* Trim trailing whitespace. */
223: ep = cp + strlen(cp) - 1;
224: while (ep > cp && (*ep == '\n' || *ep == ' ' || *ep == '\t'))
225: *ep-- = '\0';
226: /*
227: * If the line has internal whitespace then assume it has
228: * key options.
229: */
230: line_opts = NULL;
231: if ((ep = strrchr(cp, ' ')) != NULL ||
232: (ep = strrchr(cp, '\t')) != NULL) {
233: for (; *ep == ' ' || *ep == '\t'; ep++)
1.27 deraadt 234: ;
1.26 djm 235: line_opts = cp;
236: cp = ep;
237: }
1.24 djm 238: for (i = 0; i < cert->nprincipals; i++) {
239: if (strcmp(cp, cert->principals[i]) == 0) {
1.30 ! djm 240: debug3("matched principal \"%.100s\" "
! 241: "from file \"%s\" on line %lu",
! 242: cert->principals[i], file, linenum);
1.26 djm 243: if (auth_parse_options(pw, line_opts,
244: file, linenum) != 1)
245: continue;
1.24 djm 246: fclose(f);
247: restore_uid();
248: return 1;
249: }
250: }
251: }
252: fclose(f);
253: restore_uid();
254: return 0;
255: }
256:
1.1 markus 257: /* return 1 if user allows given key */
258: static int
259: user_key_allowed2(struct passwd *pw, Key *key, char *file)
260: {
1.8 dtucker 261: char line[SSH_MAX_PUBKEY_BYTES];
1.20 djm 262: const char *reason;
1.18 dtucker 263: int found_key = 0;
1.1 markus 264: FILE *f;
265: u_long linenum = 0;
266: Key *found;
267: char *fp;
268:
269: /* Temporarily use the user's uid. */
270: temporarily_use_uid(pw);
271:
272: debug("trying public key file %s", file);
1.18 dtucker 273: f = auth_openkeyfile(file, pw, options.strict_modes);
1.1 markus 274:
1.18 dtucker 275: if (!f) {
1.1 markus 276: restore_uid();
277: return 0;
278: }
279:
280: found_key = 0;
1.20 djm 281: found = key_new(key_is_cert(key) ? KEY_UNSPEC : key->type);
1.1 markus 282:
1.8 dtucker 283: while (read_keyfile_line(f, file, line, sizeof(line), &linenum) != -1) {
1.7 avsm 284: char *cp, *key_options = NULL;
1.8 dtucker 285:
1.20 djm 286: auth_clear_options();
287:
1.1 markus 288: /* Skip leading whitespace, empty and comment lines. */
289: for (cp = line; *cp == ' ' || *cp == '\t'; cp++)
290: ;
291: if (!*cp || *cp == '\n' || *cp == '#')
292: continue;
293:
294: if (key_read(found, &cp) != 1) {
295: /* no key? check if there are options for this key */
296: int quoted = 0;
297: debug2("user_key_allowed: check options: '%s'", cp);
1.7 avsm 298: key_options = cp;
1.1 markus 299: for (; *cp && (quoted || (*cp != ' ' && *cp != '\t')); cp++) {
300: if (*cp == '\\' && cp[1] == '"')
301: cp++; /* Skip both */
302: else if (*cp == '"')
303: quoted = !quoted;
304: }
305: /* Skip remaining whitespace. */
306: for (; *cp == ' ' || *cp == '\t'; cp++)
307: ;
308: if (key_read(found, &cp) != 1) {
309: debug2("user_key_allowed: advance: '%s'", cp);
310: /* still no key? advance to next line*/
311: continue;
312: }
313: }
1.23 djm 314: if (key_is_cert(key)) {
1.25 djm 315: if (!key_equal(found, key->cert->signature_key))
316: continue;
317: if (auth_parse_options(pw, key_options, file,
318: linenum) != 1)
319: continue;
1.20 djm 320: if (!key_is_cert_authority)
321: continue;
322: fp = key_fingerprint(found, SSH_FP_MD5,
323: SSH_FP_HEX);
1.22 djm 324: debug("matching CA found: file %s, line %lu, %s %s",
325: file, linenum, key_type(found), fp);
1.24 djm 326: /*
327: * If the user has specified a list of principals as
328: * a key option, then prefer that list to matching
329: * their username in the certificate principals list.
330: */
331: if (authorized_principals != NULL &&
332: !match_principals_option(authorized_principals,
333: key->cert)) {
334: reason = "Certificate does not contain an "
335: "authorized principal";
336: fail_reason:
1.22 djm 337: xfree(fp);
1.20 djm 338: error("%s", reason);
339: auth_debug_add("%s", reason);
340: continue;
341: }
1.24 djm 342: if (key_cert_check_authority(key, 0, 0,
343: authorized_principals == NULL ? pw->pw_name : NULL,
344: &reason) != 0)
345: goto fail_reason;
1.23 djm 346: if (auth_cert_options(key, pw) != 0) {
1.22 djm 347: xfree(fp);
1.20 djm 348: continue;
1.22 djm 349: }
350: verbose("Accepted certificate ID \"%s\" "
351: "signed by %s CA %s via %s", key->cert->key_id,
352: key_type(found), fp, file);
353: xfree(fp);
1.20 djm 354: found_key = 1;
355: break;
1.25 djm 356: } else if (key_equal(found, key)) {
357: if (auth_parse_options(pw, key_options, file,
358: linenum) != 1)
359: continue;
360: if (key_is_cert_authority)
361: continue;
1.1 markus 362: found_key = 1;
363: debug("matching key found: file %s, line %lu",
364: file, linenum);
365: fp = key_fingerprint(found, SSH_FP_MD5, SSH_FP_HEX);
366: verbose("Found matching %s key: %s",
367: key_type(found), fp);
368: xfree(fp);
369: break;
370: }
371: }
372: restore_uid();
373: fclose(f);
374: key_free(found);
375: if (!found_key)
376: debug2("key not found");
377: return found_key;
378: }
379:
1.21 djm 380: /* Authenticate a certificate key against TrustedUserCAKeys */
381: static int
382: user_cert_trusted_ca(struct passwd *pw, Key *key)
383: {
1.24 djm 384: char *ca_fp, *principals_file = NULL;
1.21 djm 385: const char *reason;
386: int ret = 0;
387:
388: if (!key_is_cert(key) || options.trusted_user_ca_keys == NULL)
389: return 0;
390:
1.22 djm 391: ca_fp = key_fingerprint(key->cert->signature_key,
392: SSH_FP_MD5, SSH_FP_HEX);
1.21 djm 393:
394: if (key_in_file(key->cert->signature_key,
395: options.trusted_user_ca_keys, 1) != 1) {
396: debug2("%s: CA %s %s is not listed in %s", __func__,
397: key_type(key->cert->signature_key), ca_fp,
398: options.trusted_user_ca_keys);
399: goto out;
400: }
1.24 djm 401: /*
402: * If AuthorizedPrincipals is in use, then compare the certificate
403: * principals against the names in that file rather than matching
404: * against the username.
405: */
406: if ((principals_file = authorized_principals_file(pw)) != NULL) {
407: if (!match_principals_file(principals_file, pw, key->cert)) {
408: reason = "Certificate does not contain an "
409: "authorized principal";
410: fail_reason:
411: error("%s", reason);
412: auth_debug_add("%s", reason);
413: goto out;
414: }
1.21 djm 415: }
1.24 djm 416: if (key_cert_check_authority(key, 0, 1,
417: principals_file == NULL ? pw->pw_name : NULL, &reason) != 0)
418: goto fail_reason;
1.23 djm 419: if (auth_cert_options(key, pw) != 0)
1.21 djm 420: goto out;
421:
1.22 djm 422: verbose("Accepted certificate ID \"%s\" signed by %s CA %s via %s",
423: key->cert->key_id, key_type(key->cert->signature_key), ca_fp,
424: options.trusted_user_ca_keys);
1.21 djm 425: ret = 1;
426:
427: out:
1.24 djm 428: if (principals_file != NULL)
429: xfree(principals_file);
1.21 djm 430: if (ca_fp != NULL)
431: xfree(ca_fp);
432: return ret;
433: }
434:
1.1 markus 435: /* check whether given key is in .ssh/authorized_keys* */
436: int
437: user_key_allowed(struct passwd *pw, Key *key)
438: {
1.29 djm 439: u_int success, i;
1.1 markus 440: char *file;
1.21 djm 441:
442: if (auth_key_is_revoked(key))
443: return 0;
444: if (key_is_cert(key) && auth_key_is_revoked(key->cert->signature_key))
445: return 0;
446:
447: success = user_cert_trusted_ca(pw, key);
448: if (success)
449: return success;
1.1 markus 450:
1.29 djm 451: for (i = 0; !success && i < options.num_authkeys_files; i++) {
452: file = expand_authorized_keys(
453: options.authorized_keys_files[i], pw);
454: success = user_key_allowed2(pw, key, file);
455: xfree(file);
456: }
1.1 markus 457:
458: return success;
459: }
1.2 markus 460:
461: Authmethod method_pubkey = {
462: "publickey",
463: userauth_pubkey,
464: &options.pubkey_authentication
465: };
![[BACK]](/icons/back.gif){kind=icon}
Return to auth2-pubkey.c CVS log ![[TXT]](/icons/text.gif){kind=icon}
![[DIR]](/icons/dir.gif){kind=icon}
Up to [local] / src / usr.bin / ssh