]>
Commit | Line | Data |
---|---|---|
3c0ef626 | 1 | /* |
2 | * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland | |
3 | * All rights reserved | |
4 | * | |
5 | * As far as I am concerned, the code I have written for this software | |
6 | * can be used freely for any purpose. Any derived versions of this | |
7 | * software must be clearly marked as such, and if the derived work is | |
8 | * incompatible with the protocol description in the RFC file, it must be | |
9 | * called by a name other than "ssh" or "Secure Shell". | |
10 | */ | |
11 | ||
12 | #include "includes.h" | |
7e82606e | 13 | RCSID("$OpenBSD: auth1.c,v 1.59 2004/07/28 09:40:29 markus Exp $"); |
3c0ef626 | 14 | |
15 | #include "xmalloc.h" | |
16 | #include "rsa.h" | |
17 | #include "ssh1.h" | |
18 | #include "packet.h" | |
19 | #include "buffer.h" | |
3c0ef626 | 20 | #include "log.h" |
21 | #include "servconf.h" | |
22 | #include "compat.h" | |
23 | #include "auth.h" | |
1e608e42 | 24 | #include "channels.h" |
3c0ef626 | 25 | #include "session.h" |
3c0ef626 | 26 | #include "uidswap.h" |
510132b6 | 27 | #include "monitor_wrap.h" |
3c0ef626 | 28 | |
29 | /* import */ | |
30 | extern ServerOptions options; | |
31 | ||
32 | /* | |
33 | * convert ssh auth msg type into description | |
34 | */ | |
35 | static char * | |
36 | get_authname(int type) | |
37 | { | |
38 | static char buf[1024]; | |
39 | switch (type) { | |
40 | case SSH_CMSG_AUTH_PASSWORD: | |
41 | return "password"; | |
42 | case SSH_CMSG_AUTH_RSA: | |
43 | return "rsa"; | |
44 | case SSH_CMSG_AUTH_RHOSTS_RSA: | |
45 | return "rhosts-rsa"; | |
46 | case SSH_CMSG_AUTH_RHOSTS: | |
47 | return "rhosts"; | |
48 | case SSH_CMSG_AUTH_TIS: | |
49 | case SSH_CMSG_AUTH_TIS_RESPONSE: | |
50 | return "challenge-response"; | |
3c0ef626 | 51 | } |
52 | snprintf(buf, sizeof buf, "bad-auth-msg-%d", type); | |
53 | return buf; | |
54 | } | |
55 | ||
56 | /* | |
57 | * read packets, try to authenticate the user and | |
58 | * return only if authentication is successful | |
59 | */ | |
60 | static void | |
61 | do_authloop(Authctxt *authctxt) | |
62 | { | |
63 | int authenticated = 0; | |
64 | u_int bits; | |
1e608e42 | 65 | Key *client_host_key; |
3c0ef626 | 66 | BIGNUM *n; |
67 | char *client_user, *password; | |
68 | char info[1024]; | |
69 | u_int dlen; | |
3c0ef626 | 70 | u_int ulen; |
7cac2b65 | 71 | int prev, type = 0; |
3c0ef626 | 72 | |
73 | debug("Attempting authentication for %s%.100s.", | |
7e82606e | 74 | authctxt->valid ? "" : "invalid user ", authctxt->user); |
3c0ef626 | 75 | |
76 | /* If the user has no password, accept authentication immediately. */ | |
77 | if (options.password_authentication && | |
7cac2b65 | 78 | #ifdef KRB5 |
3c0ef626 | 79 | (!options.kerberos_authentication || options.kerberos_or_local_passwd) && |
80 | #endif | |
510132b6 | 81 | PRIVSEP(auth_password(authctxt, ""))) { |
7e82606e | 82 | #ifdef USE_PAM |
83 | if (options.use_pam && (PRIVSEP(do_pam_account()))) | |
84 | #endif | |
85 | { | |
86 | auth_log(authctxt, 1, "without authentication", ""); | |
87 | return; | |
88 | } | |
3c0ef626 | 89 | } |
90 | ||
91 | /* Indicate that authentication is needed. */ | |
92 | packet_start(SSH_SMSG_FAILURE); | |
93 | packet_send(); | |
94 | packet_write_wait(); | |
95 | ||
96 | client_user = NULL; | |
97 | ||
98 | for (;;) { | |
99 | /* default to fail */ | |
100 | authenticated = 0; | |
101 | ||
102 | info[0] = '\0'; | |
103 | ||
104 | /* Get a packet from the client. */ | |
7cac2b65 | 105 | prev = type; |
1e608e42 | 106 | type = packet_read(); |
3c0ef626 | 107 | |
7cac2b65 | 108 | /* |
109 | * If we started challenge-response authentication but the | |
110 | * next packet is not a response to our challenge, release | |
111 | * the resources allocated by get_challenge() (which would | |
112 | * normally have been released by verify_response() had we | |
113 | * received such a response) | |
114 | */ | |
115 | if (prev == SSH_CMSG_AUTH_TIS && | |
116 | type != SSH_CMSG_AUTH_TIS_RESPONSE) | |
117 | abandon_challenge_response(authctxt); | |
118 | ||
3c0ef626 | 119 | /* Process the packet. */ |
120 | switch (type) { | |
3c0ef626 | 121 | case SSH_CMSG_AUTH_RHOSTS_RSA: |
122 | if (!options.rhosts_rsa_authentication) { | |
123 | verbose("Rhosts with RSA authentication disabled."); | |
124 | break; | |
125 | } | |
126 | /* | |
127 | * Get client user name. Note that we just have to | |
128 | * trust the client; root on the client machine can | |
129 | * claim to be any user. | |
130 | */ | |
131 | client_user = packet_get_string(&ulen); | |
132 | ||
133 | /* Get the client host key. */ | |
1e608e42 | 134 | client_host_key = key_new(KEY_RSA1); |
3c0ef626 | 135 | bits = packet_get_int(); |
1e608e42 | 136 | packet_get_bignum(client_host_key->rsa->e); |
137 | packet_get_bignum(client_host_key->rsa->n); | |
3c0ef626 | 138 | |
1e608e42 | 139 | if (bits != BN_num_bits(client_host_key->rsa->n)) |
3c0ef626 | 140 | verbose("Warning: keysize mismatch for client_host_key: " |
1e608e42 | 141 | "actual %d, announced %d", |
44a053a3 | 142 | BN_num_bits(client_host_key->rsa->n), bits); |
1e608e42 | 143 | packet_check_eom(); |
3c0ef626 | 144 | |
540d72c3 | 145 | authenticated = auth_rhosts_rsa(authctxt, client_user, |
1e608e42 | 146 | client_host_key); |
147 | key_free(client_host_key); | |
3c0ef626 | 148 | |
149 | snprintf(info, sizeof info, " ruser %.100s", client_user); | |
150 | break; | |
151 | ||
152 | case SSH_CMSG_AUTH_RSA: | |
153 | if (!options.rsa_authentication) { | |
154 | verbose("RSA authentication disabled."); | |
155 | break; | |
156 | } | |
157 | /* RSA authentication requested. */ | |
1e608e42 | 158 | if ((n = BN_new()) == NULL) |
159 | fatal("do_authloop: BN_new failed"); | |
160 | packet_get_bignum(n); | |
161 | packet_check_eom(); | |
540d72c3 | 162 | authenticated = auth_rsa(authctxt, n); |
3c0ef626 | 163 | BN_clear_free(n); |
164 | break; | |
165 | ||
166 | case SSH_CMSG_AUTH_PASSWORD: | |
167 | if (!options.password_authentication) { | |
168 | verbose("Password authentication disabled."); | |
169 | break; | |
170 | } | |
171 | /* | |
172 | * Read user password. It is in plain text, but was | |
173 | * transmitted over the encrypted channel so it is | |
174 | * not visible to an outside observer. | |
175 | */ | |
176 | password = packet_get_string(&dlen); | |
1e608e42 | 177 | packet_check_eom(); |
3c0ef626 | 178 | |
3c0ef626 | 179 | /* Try authentication with the password. */ |
510132b6 | 180 | authenticated = PRIVSEP(auth_password(authctxt, password)); |
3c0ef626 | 181 | |
182 | memset(password, 0, strlen(password)); | |
183 | xfree(password); | |
184 | break; | |
185 | ||
186 | case SSH_CMSG_AUTH_TIS: | |
187 | debug("rcvd SSH_CMSG_AUTH_TIS"); | |
188 | if (options.challenge_response_authentication == 1) { | |
189 | char *challenge = get_challenge(authctxt); | |
190 | if (challenge != NULL) { | |
191 | debug("sending challenge '%s'", challenge); | |
192 | packet_start(SSH_SMSG_AUTH_TIS_CHALLENGE); | |
193 | packet_put_cstring(challenge); | |
194 | xfree(challenge); | |
195 | packet_send(); | |
196 | packet_write_wait(); | |
197 | continue; | |
198 | } | |
199 | } | |
200 | break; | |
201 | case SSH_CMSG_AUTH_TIS_RESPONSE: | |
202 | debug("rcvd SSH_CMSG_AUTH_TIS_RESPONSE"); | |
203 | if (options.challenge_response_authentication == 1) { | |
204 | char *response = packet_get_string(&dlen); | |
1e608e42 | 205 | packet_check_eom(); |
3c0ef626 | 206 | authenticated = verify_response(authctxt, response); |
207 | memset(response, 'r', dlen); | |
208 | xfree(response); | |
209 | } | |
210 | break; | |
211 | ||
212 | default: | |
213 | /* | |
214 | * Any unknown messages will be ignored (and failure | |
215 | * returned) during authentication. | |
216 | */ | |
7cac2b65 | 217 | logit("Unknown message during authentication: type %d", type); |
3c0ef626 | 218 | break; |
219 | } | |
220 | #ifdef BSD_AUTH | |
221 | if (authctxt->as) { | |
222 | auth_close(authctxt->as); | |
223 | authctxt->as = NULL; | |
224 | } | |
225 | #endif | |
226 | if (!authctxt->valid && authenticated) | |
227 | fatal("INTERNAL ERROR: authenticated invalid user %s", | |
228 | authctxt->user); | |
229 | ||
d03f4262 | 230 | #ifdef _UNICOS |
d03f4262 | 231 | if (authenticated && cray_access_denied(authctxt->user)) { |
232 | authenticated = 0; | |
233 | fatal("Access denied for user %s.",authctxt->user); | |
234 | } | |
235 | #endif /* _UNICOS */ | |
236 | ||
3c0ef626 | 237 | #ifdef HAVE_CYGWIN |
238 | if (authenticated && | |
7e82606e | 239 | !check_nt_auth(type == SSH_CMSG_AUTH_PASSWORD, |
240 | authctxt->pw)) { | |
3c0ef626 | 241 | packet_disconnect("Authentication rejected for uid %d.", |
7e82606e | 242 | authctxt->pw == NULL ? -1 : authctxt->pw->pw_uid); |
3c0ef626 | 243 | authenticated = 0; |
244 | } | |
245 | #else | |
246 | /* Special handling for root */ | |
bfe49944 | 247 | if (authenticated && authctxt->pw->pw_uid == 0 && |
3c0ef626 | 248 | !auth_root_allowed(get_authname(type))) |
249 | authenticated = 0; | |
250 | #endif | |
7cac2b65 | 251 | |
3c0ef626 | 252 | #ifdef USE_PAM |
540d72c3 | 253 | if (options.use_pam && authenticated && |
7cac2b65 | 254 | !PRIVSEP(do_pam_account())) |
3c0ef626 | 255 | authenticated = 0; |
256 | #endif | |
257 | ||
258 | /* Log before sending the reply */ | |
259 | auth_log(authctxt, authenticated, get_authname(type), info); | |
260 | ||
261 | if (client_user != NULL) { | |
262 | xfree(client_user); | |
263 | client_user = NULL; | |
264 | } | |
265 | ||
266 | if (authenticated) | |
267 | return; | |
268 | ||
7e82606e | 269 | if (authctxt->failures++ > options.max_authtries) |
3c0ef626 | 270 | packet_disconnect(AUTH_FAIL_MSG, authctxt->user); |
3c0ef626 | 271 | |
272 | packet_start(SSH_SMSG_FAILURE); | |
273 | packet_send(); | |
274 | packet_write_wait(); | |
275 | } | |
276 | } | |
277 | ||
278 | /* | |
279 | * Performs authentication of an incoming connection. Session key has already | |
280 | * been exchanged and encryption is enabled. | |
281 | */ | |
540d72c3 | 282 | void |
283 | do_authentication(Authctxt *authctxt) | |
3c0ef626 | 284 | { |
3c0ef626 | 285 | u_int ulen; |
510132b6 | 286 | char *user, *style = NULL; |
3c0ef626 | 287 | |
288 | /* Get the name of the user that we wish to log in as. */ | |
1e608e42 | 289 | packet_read_expect(SSH_CMSG_USER); |
3c0ef626 | 290 | |
291 | /* Get the user name. */ | |
292 | user = packet_get_string(&ulen); | |
1e608e42 | 293 | packet_check_eom(); |
3c0ef626 | 294 | |
295 | if ((style = strchr(user, ':')) != NULL) | |
296 | *style++ = '\0'; | |
297 | ||
3c0ef626 | 298 | authctxt->user = user; |
299 | authctxt->style = style; | |
300 | ||
301 | /* Verify that the user is a valid user. */ | |
510132b6 | 302 | if ((authctxt->pw = PRIVSEP(getpwnamallow(user))) != NULL) |
3c0ef626 | 303 | authctxt->valid = 1; |
7cac2b65 | 304 | else { |
7e82606e | 305 | debug("do_authentication: invalid user %s", user); |
7cac2b65 | 306 | authctxt->pw = fakepw(); |
307 | } | |
3c0ef626 | 308 | |
7e82606e | 309 | setproctitle("%s%s", authctxt->valid ? user : "unknown", |
510132b6 | 310 | use_privsep ? " [net]" : ""); |
3c0ef626 | 311 | |
312 | #ifdef USE_PAM | |
7cac2b65 | 313 | if (options.use_pam) |
12a403af | 314 | PRIVSEP(start_pam(authctxt)); |
3c0ef626 | 315 | #endif |
316 | ||
317 | /* | |
318 | * If we are not running as root, the user must have the same uid as | |
319 | * the server. (Unless you are running Windows) | |
320 | */ | |
321 | #ifndef HAVE_CYGWIN | |
510132b6 | 322 | if (!use_privsep && getuid() != 0 && authctxt->pw && |
323 | authctxt->pw->pw_uid != getuid()) | |
3c0ef626 | 324 | packet_disconnect("Cannot change user when server not running as root."); |
325 | #endif | |
326 | ||
327 | /* | |
328 | * Loop until the user has been authenticated or the connection is | |
329 | * closed, do_authloop() returns only if authentication is successful | |
330 | */ | |
331 | do_authloop(authctxt); | |
332 | ||
333 | /* The user has been authenticated and accepted. */ | |
334 | packet_start(SSH_SMSG_SUCCESS); | |
335 | packet_send(); | |
336 | packet_write_wait(); | |
3c0ef626 | 337 | } |