Annotation of src/usr.bin/ssh/auth-rhosts.c, Revision 1.35
1.1 deraadt 1: /*
1.10 deraadt 2: * Author: Tatu Ylonen <ylo@cs.hut.fi>
3: * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
4: * All rights reserved
5: * Rhosts authentication. This file contains code to check whether to admit
6: * the login based on rhosts authentication. This file also processes
7: * /etc/hosts.equiv.
1.13 markus 8: *
1.15 deraadt 9: * As far as I am concerned, the code I have written for this software
10: * can be used freely for any purpose. Any derived versions of this
11: * software must be clearly marked as such, and if the derived work is
12: * incompatible with the protocol description in the RFC file, it must be
13: * called by a name other than "ssh" or "Secure Shell".
1.10 deraadt 14: */
1.1 deraadt 15:
16: #include "includes.h"
1.35 ! stevesk 17: RCSID("$OpenBSD: auth-rhosts.c,v 1.34 2006/02/07 01:08:04 stevesk Exp $");
! 18:
! 19: #include <sys/types.h>
! 20: #include <sys/stat.h>
1.34 stevesk 21:
22: #include <netgroup.h>
1.1 deraadt 23:
24: #include "packet.h"
25: #include "uidswap.h"
1.19 markus 26: #include "pathnames.h"
27: #include "log.h"
1.6 markus 28: #include "servconf.h"
1.19 markus 29: #include "canohost.h"
1.21 itojun 30: #include "auth.h"
1.1 deraadt 31:
1.23 markus 32: /* import */
33: extern ServerOptions options;
1.28 markus 34: extern int use_privsep;
1.23 markus 35:
1.11 markus 36: /*
37: * This function processes an rhosts-style file (.rhosts, .shosts, or
38: * /etc/hosts.equiv). This returns true if authentication can be granted
39: * based on the file, and returns zero otherwise.
40: */
1.1 deraadt 41:
1.24 itojun 42: static int
1.9 markus 43: check_rhosts_file(const char *filename, const char *hostname,
44: const char *ipaddr, const char *client_user,
45: const char *server_user)
1.1 deraadt 46: {
1.9 markus 47: FILE *f;
48: char buf[1024]; /* Must not be larger than host, user, dummy below. */
1.1 deraadt 49:
1.9 markus 50: /* Open the .rhosts file, deny if unreadable */
51: f = fopen(filename, "r");
52: if (!f)
53: return 0;
54:
55: while (fgets(buf, sizeof(buf), f)) {
56: /* All three must be at least as big as buf to avoid overflows. */
57: char hostbuf[1024], userbuf[1024], dummy[1024], *host, *user, *cp;
58: int negated;
59:
60: for (cp = buf; *cp == ' ' || *cp == '\t'; cp++)
61: ;
62: if (*cp == '#' || *cp == '\n' || !*cp)
63: continue;
64:
1.11 markus 65: /*
66: * NO_PLUS is supported at least on OSF/1. We skip it (we
67: * don't ever support the plus syntax).
68: */
1.9 markus 69: if (strncmp(cp, "NO_PLUS", 7) == 0)
70: continue;
71:
1.11 markus 72: /*
73: * This should be safe because each buffer is as big as the
74: * whole string, and thus cannot be overwritten.
75: */
1.30 itojun 76: switch (sscanf(buf, "%1023s %1023s %1023s", hostbuf, userbuf,
77: dummy)) {
1.9 markus 78: case 0:
1.28 markus 79: auth_debug_add("Found empty line in %.100s.", filename);
1.9 markus 80: continue;
81: case 1:
82: /* Host name only. */
83: strlcpy(userbuf, server_user, sizeof(userbuf));
84: break;
85: case 2:
86: /* Got both host and user name. */
87: break;
88: case 3:
1.28 markus 89: auth_debug_add("Found garbage in %.100s.", filename);
1.9 markus 90: continue;
91: default:
92: /* Weird... */
93: continue;
94: }
95:
96: host = hostbuf;
97: user = userbuf;
98: negated = 0;
99:
100: /* Process negated host names, or positive netgroups. */
101: if (host[0] == '-') {
102: negated = 1;
103: host++;
104: } else if (host[0] == '+')
105: host++;
106:
107: if (user[0] == '-') {
108: negated = 1;
109: user++;
110: } else if (user[0] == '+')
111: user++;
112:
113: /* Check for empty host/user names (particularly '+'). */
114: if (!host[0] || !user[0]) {
115: /* We come here if either was '+' or '-'. */
1.28 markus 116: auth_debug_add("Ignoring wild host/user names in %.100s.",
117: filename);
1.9 markus 118: continue;
119: }
120: /* Verify that host name matches. */
121: if (host[0] == '@') {
122: if (!innetgr(host + 1, hostname, NULL, NULL) &&
123: !innetgr(host + 1, ipaddr, NULL, NULL))
124: continue;
125: } else if (strcasecmp(host, hostname) && strcmp(host, ipaddr) != 0)
126: continue; /* Different hostname. */
127:
128: /* Verify that user name matches. */
129: if (user[0] == '@') {
130: if (!innetgr(user + 1, NULL, client_user, NULL))
131: continue;
132: } else if (strcmp(user, client_user) != 0)
133: continue; /* Different username. */
134:
135: /* Found the user and host. */
136: fclose(f);
137:
138: /* If the entry was negated, deny access. */
139: if (negated) {
1.28 markus 140: auth_debug_add("Matched negative entry in %.100s.",
1.33 djm 141: filename);
1.9 markus 142: return 0;
143: }
144: /* Accept authentication. */
145: return 1;
146: }
147:
148: /* Authentication using this file denied. */
149: fclose(f);
150: return 0;
1.1 deraadt 151: }
152:
1.11 markus 153: /*
154: * Tries to authenticate the user using the .shosts or .rhosts file. Returns
155: * true if authentication succeeds. If ignore_rhosts is true, only
156: * /etc/hosts.equiv will be considered (.rhosts and .shosts are ignored).
157: */
1.1 deraadt 158:
1.13 markus 159: int
1.9 markus 160: auth_rhosts(struct passwd *pw, const char *client_user)
1.1 deraadt 161: {
1.23 markus 162: const char *hostname, *ipaddr;
163:
1.31 markus 164: hostname = get_canonical_hostname(options.use_dns);
1.23 markus 165: ipaddr = get_remote_ipaddr();
1.28 markus 166: return auth_rhosts2(pw, client_user, hostname, ipaddr);
1.23 markus 167: }
168:
1.28 markus 169: static int
170: auth_rhosts2_raw(struct passwd *pw, const char *client_user, const char *hostname,
1.23 markus 171: const char *ipaddr)
172: {
1.9 markus 173: char buf[1024];
174: struct stat st;
175: static const char *rhosts_files[] = {".shosts", ".rhosts", NULL};
1.17 markus 176: u_int rhosts_file_index;
1.9 markus 177:
1.23 markus 178: debug2("auth_rhosts2: clientuser %s hostname %s ipaddr %s",
179: client_user, hostname, ipaddr);
180:
1.9 markus 181: /* Switch to the user's uid. */
1.22 markus 182: temporarily_use_uid(pw);
1.11 markus 183: /*
184: * Quick check: if the user has no .shosts or .rhosts files, return
185: * failure immediately without doing costly lookups from name
186: * servers.
187: */
1.9 markus 188: for (rhosts_file_index = 0; rhosts_files[rhosts_file_index];
1.25 deraadt 189: rhosts_file_index++) {
1.9 markus 190: /* Check users .rhosts or .shosts. */
191: snprintf(buf, sizeof buf, "%.500s/%.100s",
192: pw->pw_dir, rhosts_files[rhosts_file_index]);
193: if (stat(buf, &st) >= 0)
194: break;
195: }
196: /* Switch back to privileged uid. */
197: restore_uid();
198:
199: /* Deny if The user has no .shosts or .rhosts file and there are no system-wide files. */
200: if (!rhosts_files[rhosts_file_index] &&
1.18 markus 201: stat(_PATH_RHOSTS_EQUIV, &st) < 0 &&
202: stat(_PATH_SSH_HOSTS_EQUIV, &st) < 0)
1.9 markus 203: return 0;
204:
205: /* If not logging in as superuser, try /etc/hosts.equiv and shosts.equiv. */
206: if (pw->pw_uid != 0) {
1.25 deraadt 207: if (check_rhosts_file(_PATH_RHOSTS_EQUIV, hostname, ipaddr,
208: client_user, pw->pw_name)) {
1.28 markus 209: auth_debug_add("Accepted for %.100s [%.100s] by /etc/hosts.equiv.",
1.25 deraadt 210: hostname, ipaddr);
1.9 markus 211: return 1;
212: }
1.25 deraadt 213: if (check_rhosts_file(_PATH_SSH_HOSTS_EQUIV, hostname, ipaddr,
214: client_user, pw->pw_name)) {
1.28 markus 215: auth_debug_add("Accepted for %.100s [%.100s] by %.100s.",
1.25 deraadt 216: hostname, ipaddr, _PATH_SSH_HOSTS_EQUIV);
1.9 markus 217: return 1;
218: }
219: }
1.11 markus 220: /*
221: * Check that the home directory is owned by root or the user, and is
222: * not group or world writable.
223: */
1.9 markus 224: if (stat(pw->pw_dir, &st) < 0) {
1.29 itojun 225: logit("Rhosts authentication refused for %.100s: "
1.28 markus 226: "no home directory %.200s", pw->pw_name, pw->pw_dir);
227: auth_debug_add("Rhosts authentication refused for %.100s: "
228: "no home directory %.200s", pw->pw_name, pw->pw_dir);
1.9 markus 229: return 0;
230: }
231: if (options.strict_modes &&
232: ((st.st_uid != 0 && st.st_uid != pw->pw_uid) ||
1.25 deraadt 233: (st.st_mode & 022) != 0)) {
1.29 itojun 234: logit("Rhosts authentication refused for %.100s: "
1.28 markus 235: "bad ownership or modes for home directory.", pw->pw_name);
236: auth_debug_add("Rhosts authentication refused for %.100s: "
237: "bad ownership or modes for home directory.", pw->pw_name);
1.9 markus 238: return 0;
239: }
240: /* Temporarily use the user's uid. */
1.22 markus 241: temporarily_use_uid(pw);
1.9 markus 242:
243: /* Check all .rhosts files (currently .shosts and .rhosts). */
244: for (rhosts_file_index = 0; rhosts_files[rhosts_file_index];
1.25 deraadt 245: rhosts_file_index++) {
1.9 markus 246: /* Check users .rhosts or .shosts. */
247: snprintf(buf, sizeof buf, "%.500s/%.100s",
248: pw->pw_dir, rhosts_files[rhosts_file_index]);
249: if (stat(buf, &st) < 0)
250: continue;
251:
1.11 markus 252: /*
253: * Make sure that the file is either owned by the user or by
254: * root, and make sure it is not writable by anyone but the
255: * owner. This is to help avoid novices accidentally
256: * allowing access to their account by anyone.
257: */
1.9 markus 258: if (options.strict_modes &&
259: ((st.st_uid != 0 && st.st_uid != pw->pw_uid) ||
1.25 deraadt 260: (st.st_mode & 022) != 0)) {
1.29 itojun 261: logit("Rhosts authentication refused for %.100s: bad modes for %.200s",
1.9 markus 262: pw->pw_name, buf);
1.28 markus 263: auth_debug_add("Bad file modes for %.200s", buf);
1.9 markus 264: continue;
265: }
266: /* Check if we have been configured to ignore .rhosts and .shosts files. */
267: if (options.ignore_rhosts) {
1.28 markus 268: auth_debug_add("Server has been configured to ignore %.100s.",
269: rhosts_files[rhosts_file_index]);
1.9 markus 270: continue;
271: }
272: /* Check if authentication is permitted by the file. */
273: if (check_rhosts_file(buf, hostname, ipaddr, client_user, pw->pw_name)) {
1.28 markus 274: auth_debug_add("Accepted by %.100s.",
275: rhosts_files[rhosts_file_index]);
1.9 markus 276: /* Restore the privileged uid. */
277: restore_uid();
1.28 markus 278: auth_debug_add("Accepted host %s ip %s client_user %s server_user %s",
279: hostname, ipaddr, client_user, pw->pw_name);
1.9 markus 280: return 1;
281: }
282: }
283:
284: /* Restore the privileged uid. */
285: restore_uid();
286: return 0;
1.28 markus 287: }
288:
289: int
290: auth_rhosts2(struct passwd *pw, const char *client_user, const char *hostname,
291: const char *ipaddr)
292: {
293: int ret;
294:
295: auth_debug_reset();
296: ret = auth_rhosts2_raw(pw, client_user, hostname, ipaddr);
297: if (!use_privsep)
298: auth_debug_send();
299: return ret;
1.1 deraadt 300: }
![[BACK]](/icons/back.gif){kind=icon}
Return to auth-rhosts.c CVS log ![[TXT]](/icons/text.gif){kind=icon}
![[DIR]](/icons/dir.gif){kind=icon}
Up to [local] / src / usr.bin / ssh