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);