Annotation of src/usr.bin/ssh/auth.c, Revision 1.71
1.71 ! dtucker 1: /* $OpenBSD: auth.c,v 1.70 2006/07/11 20:07:25 stevesk Exp $ */
1.1 markus 2: /*
1.19 deraadt 3: * Copyright (c) 2000 Markus Friedl. All rights reserved.
1.9 deraadt 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.
1.1 markus 24: */
25:
26: #include "includes.h"
1.62 stevesk 27:
28: #include <sys/types.h>
29: #include <sys/stat.h>
1.22 markus 30:
1.70 stevesk 31: #include <errno.h>
1.22 markus 32: #include <libgen.h>
1.61 stevesk 33: #include <paths.h>
1.68 stevesk 34: #include <pwd.h>
1.69 stevesk 35: #include <stdarg.h>
1.1 markus 36:
37: #include "xmalloc.h"
1.13 markus 38: #include "match.h"
1.14 markus 39: #include "groupaccess.h"
40: #include "log.h"
1.1 markus 41: #include "servconf.h"
1.2 markus 42: #include "auth.h"
1.13 markus 43: #include "auth-options.h"
1.14 markus 44: #include "canohost.h"
1.22 markus 45: #include "buffer.h"
46: #include "bufaux.h"
1.24 markus 47: #include "uidswap.h"
1.40 markus 48: #include "misc.h"
1.42 markus 49: #include "bufaux.h"
50: #include "packet.h"
1.67 dtucker 51: #include "monitor_wrap.h"
1.2 markus 52:
1.1 markus 53: /* import */
54: extern ServerOptions options;
1.67 dtucker 55: extern int use_privsep;
1.1 markus 56:
1.42 markus 57: /* Debugging messages */
58: Buffer auth_debug;
59: int auth_debug_init;
60:
1.1 markus 61: /*
1.12 markus 62: * Check if the user is allowed to log in via ssh. If user is listed
63: * in DenyUsers or one of user's groups is listed in DenyGroups, false
64: * will be returned. If AllowUsers isn't empty and user isn't listed
65: * there, or if AllowGroups isn't empty and one of user's groups isn't
66: * listed there, false will be returned.
1.1 markus 67: * If the user's shell is not executable, false will be returned.
1.4 markus 68: * Otherwise true is returned.
1.1 markus 69: */
1.5 markus 70: int
1.1 markus 71: allowed_user(struct passwd * pw)
72: {
73: struct stat st;
1.35 markus 74: const char *hostname = NULL, *ipaddr = NULL;
1.21 markus 75: char *shell;
1.60 djm 76: u_int i;
1.1 markus 77:
78: /* Shouldn't be called if pw is NULL, but better safe than sorry... */
1.12 markus 79: if (!pw || !pw->pw_name)
1.1 markus 80: return 0;
81:
1.7 deraadt 82: /*
83: * Get the shell from the password data. An empty shell field is
84: * legal, and means /bin/sh.
85: */
86: shell = (pw->pw_shell[0] == '\0') ? _PATH_BSHELL : pw->pw_shell;
87:
1.1 markus 88: /* deny if shell does not exists or is not executable */
1.34 stevesk 89: if (stat(shell, &st) != 0) {
1.47 itojun 90: logit("User %.100s not allowed because shell %.100s does not exist",
1.34 stevesk 91: pw->pw_name, shell);
1.1 markus 92: return 0;
1.34 stevesk 93: }
1.36 itojun 94: if (S_ISREG(st.st_mode) == 0 ||
95: (st.st_mode & (S_IXOTH|S_IXUSR|S_IXGRP)) == 0) {
1.47 itojun 96: logit("User %.100s not allowed because shell %.100s is not executable",
1.34 stevesk 97: pw->pw_name, shell);
1.1 markus 98: return 0;
1.34 stevesk 99: }
1.1 markus 100:
1.58 dtucker 101: if (options.num_deny_users > 0 || options.num_allow_users > 0 ||
102: options.num_deny_groups > 0 || options.num_allow_groups > 0) {
1.48 markus 103: hostname = get_canonical_hostname(options.use_dns);
1.35 markus 104: ipaddr = get_remote_ipaddr();
105: }
106:
1.1 markus 107: /* Return false if user is listed in DenyUsers */
108: if (options.num_deny_users > 0) {
109: for (i = 0; i < options.num_deny_users; i++)
1.39 markus 110: if (match_user(pw->pw_name, hostname, ipaddr,
1.34 stevesk 111: options.deny_users[i])) {
1.57 dtucker 112: logit("User %.100s from %.100s not allowed "
113: "because listed in DenyUsers",
114: pw->pw_name, hostname);
1.1 markus 115: return 0;
1.34 stevesk 116: }
1.1 markus 117: }
118: /* Return false if AllowUsers isn't empty and user isn't listed there */
119: if (options.num_allow_users > 0) {
120: for (i = 0; i < options.num_allow_users; i++)
1.39 markus 121: if (match_user(pw->pw_name, hostname, ipaddr,
1.26 markus 122: options.allow_users[i]))
1.1 markus 123: break;
124: /* i < options.num_allow_users iff we break for loop */
1.34 stevesk 125: if (i >= options.num_allow_users) {
1.57 dtucker 126: logit("User %.100s from %.100s not allowed because "
127: "not listed in AllowUsers", pw->pw_name, hostname);
1.1 markus 128: return 0;
1.34 stevesk 129: }
1.1 markus 130: }
131: if (options.num_deny_groups > 0 || options.num_allow_groups > 0) {
1.12 markus 132: /* Get the user's group access list (primary and supplementary) */
1.34 stevesk 133: if (ga_init(pw->pw_name, pw->pw_gid) == 0) {
1.57 dtucker 134: logit("User %.100s from %.100s not allowed because "
135: "not in any group", pw->pw_name, hostname);
1.1 markus 136: return 0;
1.34 stevesk 137: }
1.1 markus 138:
1.12 markus 139: /* Return false if one of user's groups is listed in DenyGroups */
140: if (options.num_deny_groups > 0)
141: if (ga_match(options.deny_groups,
142: options.num_deny_groups)) {
143: ga_free();
1.57 dtucker 144: logit("User %.100s from %.100s not allowed "
145: "because a group is listed in DenyGroups",
146: pw->pw_name, hostname);
1.1 markus 147: return 0;
1.12 markus 148: }
1.1 markus 149: /*
1.12 markus 150: * Return false if AllowGroups isn't empty and one of user's groups
1.1 markus 151: * isn't listed there
152: */
1.12 markus 153: if (options.num_allow_groups > 0)
154: if (!ga_match(options.allow_groups,
155: options.num_allow_groups)) {
156: ga_free();
1.57 dtucker 157: logit("User %.100s from %.100s not allowed "
158: "because none of user's groups are listed "
159: "in AllowGroups", pw->pw_name, hostname);
1.1 markus 160: return 0;
1.12 markus 161: }
162: ga_free();
1.1 markus 163: }
164: /* We found no reason not to let this user try to log on... */
165: return 1;
1.13 markus 166: }
167:
168: void
169: auth_log(Authctxt *authctxt, int authenticated, char *method, char *info)
170: {
171: void (*authlog) (const char *fmt,...) = verbose;
172: char *authmsg;
1.67 dtucker 173:
174: if (use_privsep && !mm_is_monitor() && !authctxt->postponed)
175: return;
1.13 markus 176:
177: /* Raise logging level */
178: if (authenticated == 1 ||
179: !authctxt->valid ||
1.54 dtucker 180: authctxt->failures >= options.max_authtries / 2 ||
1.13 markus 181: strcmp(method, "password") == 0)
1.47 itojun 182: authlog = logit;
1.13 markus 183:
184: if (authctxt->postponed)
185: authmsg = "Postponed";
186: else
187: authmsg = authenticated ? "Accepted" : "Failed";
188:
189: authlog("%s %s for %s%.100s from %.200s port %d%s",
190: authmsg,
191: method,
1.56 markus 192: authctxt->valid ? "" : "invalid user ",
1.29 markus 193: authctxt->user,
1.13 markus 194: get_remote_ipaddr(),
195: get_remote_port(),
196: info);
197: }
198:
199: /*
1.17 markus 200: * Check whether root logins are disallowed.
1.13 markus 201: */
202: int
1.17 markus 203: auth_root_allowed(char *method)
1.13 markus 204: {
1.17 markus 205: switch (options.permit_root_login) {
206: case PERMIT_YES:
1.13 markus 207: return 1;
1.17 markus 208: case PERMIT_NO_PASSWD:
209: if (strcmp(method, "password") != 0)
210: return 1;
211: break;
212: case PERMIT_FORCED_ONLY:
213: if (forced_command) {
1.47 itojun 214: logit("Root login accepted for forced command.");
1.17 markus 215: return 1;
216: }
217: break;
1.13 markus 218: }
1.47 itojun 219: logit("ROOT LOGIN REFUSED FROM %.200s", get_remote_ipaddr());
1.22 markus 220: return 0;
221: }
222:
223:
224: /*
225: * Given a template and a passwd structure, build a filename
226: * by substituting % tokenised options. Currently, %% becomes '%',
227: * %h becomes the home directory and %u the username.
228: *
229: * This returns a buffer allocated by xmalloc.
230: */
1.59 djm 231: static char *
232: expand_authorized_keys(const char *filename, struct passwd *pw)
1.22 markus 233: {
1.65 djm 234: char *file, ret[MAXPATHLEN];
235: int i;
1.22 markus 236:
1.59 djm 237: file = percent_expand(filename, "h", pw->pw_dir,
238: "u", pw->pw_name, (char *)NULL);
1.22 markus 239:
240: /*
241: * Ensure that filename starts anchored. If not, be backward
242: * compatible and prepend the '%h/'
243: */
1.59 djm 244: if (*file == '/')
245: return (file);
246:
1.65 djm 247: i = snprintf(ret, sizeof(ret), "%s/%s", pw->pw_dir, file);
248: if (i < 0 || (size_t)i >= sizeof(ret))
1.59 djm 249: fatal("expand_authorized_keys: path too long");
250: xfree(file);
1.65 djm 251: return (xstrdup(ret));
1.22 markus 252: }
253:
254: char *
255: authorized_keys_file(struct passwd *pw)
256: {
1.59 djm 257: return expand_authorized_keys(options.authorized_keys_file, pw);
1.22 markus 258: }
259:
260: char *
261: authorized_keys_file2(struct passwd *pw)
262: {
1.59 djm 263: return expand_authorized_keys(options.authorized_keys_file2, pw);
1.22 markus 264: }
1.24 markus 265:
266: /* return ok if key exists in sysfile or userfile */
267: HostStatus
268: check_key_in_hostfiles(struct passwd *pw, Key *key, const char *host,
269: const char *sysfile, const char *userfile)
270: {
271: Key *found;
272: char *user_hostfile;
273: struct stat st;
1.30 stevesk 274: HostStatus host_status;
1.24 markus 275:
276: /* Check if we know the host and its host key. */
277: found = key_new(key->type);
278: host_status = check_host_in_hostfile(sysfile, host, key, found, NULL);
279:
280: if (host_status != HOST_OK && userfile != NULL) {
281: user_hostfile = tilde_expand_filename(userfile, pw->pw_uid);
282: if (options.strict_modes &&
283: (stat(user_hostfile, &st) == 0) &&
284: ((st.st_uid != 0 && st.st_uid != pw->pw_uid) ||
1.31 deraadt 285: (st.st_mode & 022) != 0)) {
1.47 itojun 286: logit("Authentication refused for %.100s: "
1.24 markus 287: "bad owner or modes for %.200s",
288: pw->pw_name, user_hostfile);
289: } else {
290: temporarily_use_uid(pw);
291: host_status = check_host_in_hostfile(user_hostfile,
292: host, key, found, NULL);
293: restore_uid();
294: }
295: xfree(user_hostfile);
296: }
297: key_free(found);
298:
299: debug2("check_key_in_hostfiles: key %s for %s", host_status == HOST_OK ?
300: "ok" : "not found", host);
301: return host_status;
302: }
303:
1.22 markus 304:
305: /*
306: * Check a given file for security. This is defined as all components
1.44 stevesk 307: * of the path to the file must be owned by either the owner of
1.23 markus 308: * of the file or root and no directories must be group or world writable.
1.22 markus 309: *
310: * XXX Should any specific check be done for sym links ?
311: *
312: * Takes an open file descriptor, the file name, a uid and and
313: * error buffer plus max size as arguments.
314: *
315: * Returns 0 on success and -1 on failure
316: */
317: int
1.25 provos 318: secure_filename(FILE *f, const char *file, struct passwd *pw,
319: char *err, size_t errlen)
1.22 markus 320: {
1.25 provos 321: uid_t uid = pw->pw_uid;
1.28 markus 322: char buf[MAXPATHLEN], homedir[MAXPATHLEN];
1.22 markus 323: char *cp;
1.46 markus 324: int comparehome = 0;
1.22 markus 325: struct stat st;
326:
327: if (realpath(file, buf) == NULL) {
328: snprintf(err, errlen, "realpath %s failed: %s", file,
329: strerror(errno));
330: return -1;
331: }
1.46 markus 332: if (realpath(pw->pw_dir, homedir) != NULL)
333: comparehome = 1;
1.22 markus 334:
335: /* check the open file to avoid races */
336: if (fstat(fileno(f), &st) < 0 ||
337: (st.st_uid != 0 && st.st_uid != uid) ||
338: (st.st_mode & 022) != 0) {
339: snprintf(err, errlen, "bad ownership or modes for file %s",
340: buf);
341: return -1;
342: }
343:
344: /* for each component of the canonical path, walking upwards */
345: for (;;) {
346: if ((cp = dirname(buf)) == NULL) {
347: snprintf(err, errlen, "dirname() failed");
348: return -1;
349: }
350: strlcpy(buf, cp, sizeof(buf));
1.25 provos 351:
1.22 markus 352: debug3("secure_filename: checking '%s'", buf);
353: if (stat(buf, &st) < 0 ||
354: (st.st_uid != 0 && st.st_uid != uid) ||
355: (st.st_mode & 022) != 0) {
1.31 deraadt 356: snprintf(err, errlen,
1.22 markus 357: "bad ownership or modes for directory %s", buf);
358: return -1;
359: }
360:
1.27 markus 361: /* If are passed the homedir then we can stop */
1.46 markus 362: if (comparehome && strcmp(homedir, buf) == 0) {
1.27 markus 363: debug3("secure_filename: terminating check at '%s'",
364: buf);
365: break;
366: }
1.22 markus 367: /*
368: * dirname should always complete with a "/" path,
369: * but we can be paranoid and check for "." too
370: */
371: if ((strcmp("/", buf) == 0) || (strcmp(".", buf) == 0))
372: break;
373: }
1.17 markus 374: return 0;
1.37 provos 375: }
376:
377: struct passwd *
378: getpwnamallow(const char *user)
379: {
1.38 provos 380: #ifdef HAVE_LOGIN_CAP
381: extern login_cap_t *lc;
382: #ifdef BSD_AUTH
383: auth_session_t *as;
384: #endif
385: #endif
1.37 provos 386: struct passwd *pw;
1.71 ! dtucker 387:
! 388: parse_server_match_config(&options, user,
! 389: get_canonical_hostname(options.use_dns), get_remote_ipaddr());
1.37 provos 390:
391: pw = getpwnam(user);
1.45 stevesk 392: if (pw == NULL) {
1.55 markus 393: logit("Invalid user %.100s from %.100s",
1.45 stevesk 394: user, get_remote_ipaddr());
395: return (NULL);
396: }
397: if (!allowed_user(pw))
1.38 provos 398: return (NULL);
399: #ifdef HAVE_LOGIN_CAP
400: if ((lc = login_getclass(pw->pw_class)) == NULL) {
401: debug("unable to get login class: %s", user);
402: return (NULL);
403: }
404: #ifdef BSD_AUTH
405: if ((as = auth_open()) == NULL || auth_setpwd(as, pw) != 0 ||
1.43 millert 406: auth_approval(as, lc, pw->pw_name, "ssh") <= 0) {
1.38 provos 407: debug("Approval failure for %s", user);
1.37 provos 408: pw = NULL;
1.38 provos 409: }
410: if (as != NULL)
411: auth_close(as);
412: #endif
413: #endif
1.41 markus 414: if (pw != NULL)
415: return (pwcopy(pw));
416: return (NULL);
1.42 markus 417: }
418:
419: void
420: auth_debug_add(const char *fmt,...)
421: {
422: char buf[1024];
423: va_list args;
424:
425: if (!auth_debug_init)
426: return;
427:
428: va_start(args, fmt);
429: vsnprintf(buf, sizeof(buf), fmt, args);
430: va_end(args);
431: buffer_put_cstring(&auth_debug, buf);
432: }
433:
434: void
435: auth_debug_send(void)
436: {
437: char *msg;
438:
439: if (!auth_debug_init)
440: return;
441: while (buffer_len(&auth_debug)) {
442: msg = buffer_get_string(&auth_debug, NULL);
443: packet_send_debug("%s", msg);
444: xfree(msg);
445: }
446: }
447:
448: void
449: auth_debug_reset(void)
450: {
451: if (auth_debug_init)
452: buffer_clear(&auth_debug);
453: else {
454: buffer_init(&auth_debug);
455: auth_debug_init = 1;
456: }
1.49 markus 457: }
458:
459: struct passwd *
460: fakepw(void)
461: {
462: static struct passwd fake;
463:
464: memset(&fake, 0, sizeof(fake));
465: fake.pw_name = "NOUSER";
466: fake.pw_passwd =
1.51 djm 467: "$2a$06$r3.juUaHZDlIbQaO2dS9FuYxL1W9M81R1Tc92PoSNmzvpEqLkLGrK";
1.49 markus 468: fake.pw_gecos = "NOUSER";
1.53 deraadt 469: fake.pw_uid = (uid_t)-1;
470: fake.pw_gid = (gid_t)-1;
1.49 markus 471: fake.pw_class = "";
472: fake.pw_dir = "/nonexist";
473: fake.pw_shell = "/nonexist";
474:
475: return (&fake);
1.1 markus 476: }
![[BACK]](/icons/back.gif){kind=icon}
Return to auth.c CVS log ![[TXT]](/icons/text.gif){kind=icon}
![[DIR]](/icons/dir.gif){kind=icon}
Up to [local] / src / usr.bin / ssh