2 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
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".
13 RCSID("$OpenBSD: auth1.c,v 1.59 2004/07/28 09:40:29 markus Exp $");
27 #include "monitor_wrap.h"
30 extern ServerOptions options
;
33 * convert ssh auth msg type into description
36 get_authname(int type
)
38 static char buf
[1024];
40 case SSH_CMSG_AUTH_PASSWORD
:
42 case SSH_CMSG_AUTH_RSA
:
44 case SSH_CMSG_AUTH_RHOSTS_RSA
:
46 case SSH_CMSG_AUTH_RHOSTS
:
48 case SSH_CMSG_AUTH_TIS
:
49 case SSH_CMSG_AUTH_TIS_RESPONSE
:
50 return "challenge-response";
52 snprintf(buf
, sizeof buf
, "bad-auth-msg-%d", type
);
57 * read packets, try to authenticate the user and
58 * return only if authentication is successful
61 do_authloop(Authctxt
*authctxt
)
63 int authenticated
= 0;
67 char *client_user
, *password
;
73 debug("Attempting authentication for %s%.100s.",
74 authctxt
->valid
? "" : "invalid user ", authctxt
->user
);
76 /* If the user has no password, accept authentication immediately. */
77 if (options
.password_authentication
&&
79 (!options
.kerberos_authentication
|| options
.kerberos_or_local_passwd
) &&
81 PRIVSEP(auth_password(authctxt
, ""))) {
83 if (options
.use_pam
&& (PRIVSEP(do_pam_account())))
86 auth_log(authctxt
, 1, "without authentication", "");
91 /* Indicate that authentication is needed. */
92 packet_start(SSH_SMSG_FAILURE
);
104 /* Get a packet from the client. */
106 type
= packet_read();
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)
115 if (prev
== SSH_CMSG_AUTH_TIS
&&
116 type
!= SSH_CMSG_AUTH_TIS_RESPONSE
)
117 abandon_challenge_response(authctxt
);
119 /* Process the packet. */
121 case SSH_CMSG_AUTH_RHOSTS_RSA
:
122 if (!options
.rhosts_rsa_authentication
) {
123 verbose("Rhosts with RSA authentication disabled.");
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.
131 client_user
= packet_get_string(&ulen
);
133 /* Get the client host key. */
134 client_host_key
= key_new(KEY_RSA1
);
135 bits
= packet_get_int();
136 packet_get_bignum(client_host_key
->rsa
->e
);
137 packet_get_bignum(client_host_key
->rsa
->n
);
139 if (bits
!= BN_num_bits(client_host_key
->rsa
->n
))
140 verbose("Warning: keysize mismatch for client_host_key: "
141 "actual %d, announced %d",
142 BN_num_bits(client_host_key
->rsa
->n
), bits
);
145 authenticated
= auth_rhosts_rsa(authctxt
, client_user
,
147 key_free(client_host_key
);
149 snprintf(info
, sizeof info
, " ruser %.100s", client_user
);
152 case SSH_CMSG_AUTH_RSA
:
153 if (!options
.rsa_authentication
) {
154 verbose("RSA authentication disabled.");
157 /* RSA authentication requested. */
158 if ((n
= BN_new()) == NULL
)
159 fatal("do_authloop: BN_new failed");
160 packet_get_bignum(n
);
162 authenticated
= auth_rsa(authctxt
, n
);
166 case SSH_CMSG_AUTH_PASSWORD
:
167 if (!options
.password_authentication
) {
168 verbose("Password authentication disabled.");
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.
176 password
= packet_get_string(&dlen
);
179 /* Try authentication with the password. */
180 authenticated
= PRIVSEP(auth_password(authctxt
, password
));
182 memset(password
, 0, strlen(password
));
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
);
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
);
206 authenticated
= verify_response(authctxt
, response
);
207 memset(response
, 'r', dlen
);
214 * Any unknown messages will be ignored (and failure
215 * returned) during authentication.
217 logit("Unknown message during authentication: type %d", type
);
222 auth_close(authctxt
->as
);
226 if (!authctxt
->valid
&& authenticated
)
227 fatal("INTERNAL ERROR: authenticated invalid user %s",
231 if (authenticated
&& cray_access_denied(authctxt
->user
)) {
233 fatal("Access denied for user %s.",authctxt
->user
);
239 !check_nt_auth(type
== SSH_CMSG_AUTH_PASSWORD
,
241 packet_disconnect("Authentication rejected for uid %d.",
242 authctxt
->pw
== NULL
? -1 : authctxt
->pw
->pw_uid
);
246 /* Special handling for root */
247 if (authenticated
&& authctxt
->pw
->pw_uid
== 0 &&
248 !auth_root_allowed(get_authname(type
)))
253 if (options
.use_pam
&& authenticated
&&
254 !PRIVSEP(do_pam_account()))
258 /* Log before sending the reply */
259 auth_log(authctxt
, authenticated
, get_authname(type
), info
);
261 if (client_user
!= NULL
) {
269 if (authctxt
->failures
++ > options
.max_authtries
)
270 packet_disconnect(AUTH_FAIL_MSG
, authctxt
->user
);
272 packet_start(SSH_SMSG_FAILURE
);
279 * Performs authentication of an incoming connection. Session key has already
280 * been exchanged and encryption is enabled.
283 do_authentication(Authctxt
*authctxt
)
286 char *user
, *style
= NULL
;
288 /* Get the name of the user that we wish to log in as. */
289 packet_read_expect(SSH_CMSG_USER
);
291 /* Get the user name. */
292 user
= packet_get_string(&ulen
);
295 if ((style
= strchr(user
, ':')) != NULL
)
298 authctxt
->user
= user
;
299 authctxt
->style
= style
;
301 /* Verify that the user is a valid user. */
302 if ((authctxt
->pw
= PRIVSEP(getpwnamallow(user
))) != NULL
)
305 debug("do_authentication: invalid user %s", user
);
306 authctxt
->pw
= fakepw();
309 setproctitle("%s%s", authctxt
->valid
? user
: "unknown",
310 use_privsep
? " [net]" : "");
314 PRIVSEP(start_pam(authctxt
));
318 * If we are not running as root, the user must have the same uid as
319 * the server. (Unless you are running Windows)
322 if (!use_privsep
&& getuid() != 0 && authctxt
->pw
&&
323 authctxt
->pw
->pw_uid
!= getuid())
324 packet_disconnect("Cannot change user when server not running as root.");
328 * Loop until the user has been authenticated or the connection is
329 * closed, do_authloop() returns only if authentication is successful
331 do_authloop(authctxt
);
333 /* The user has been authenticated and accepted. */
334 packet_start(SSH_SMSG_SUCCESS
);