+/* $OpenBSD: auth2.c,v 1.121 2009/06/22 05:39:28 dtucker Exp $ */
/*
* Copyright (c) 2000 Markus Friedl. All rights reserved.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
- * 3. All advertising materials mentioning features or use of this software
- * must display the following acknowledgement:
- * This product includes software developed by Markus Friedl.
- * 4. The name of the author may not be used to endorse or promote products
- * derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
+
#include "includes.h"
-RCSID("$OpenBSD: auth2.c,v 1.5 2000/05/01 23:13:39 djm Exp $");
-#include <openssl/dsa.h>
-#include <openssl/rsa.h>
-#include <openssl/evp.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <sys/uio.h>
+
+#include <fcntl.h>
+#include <pwd.h>
+#include <stdarg.h>
+#include <string.h>
+#include <unistd.h>
+#include "atomicio.h"
#include "xmalloc.h"
-#include "rsa.h"
-#include "ssh.h"
-#include "pty.h"
+#include "ssh2.h"
#include "packet.h"
+#include "log.h"
#include "buffer.h"
-#include "cipher.h"
#include "servconf.h"
#include "compat.h"
-#include "channels.h"
-#include "bufaux.h"
-#include "ssh2.h"
+#include "key.h"
+#include "hostfile.h"
#include "auth.h"
-#include "session.h"
#include "dispatch.h"
-#include "auth.h"
-#include "key.h"
-#include "kex.h"
+#include "pathnames.h"
+#include "buffer.h"
-#include "dsa.h"
-#include "uidswap.h"
+#ifdef GSSAPI
+#include "ssh-gss.h"
+#endif
+#include "monitor_wrap.h"
/* import */
extern ServerOptions options;
-extern unsigned char *session_id2;
-extern int session_id2_len;
+extern u_char *session_id2;
+extern u_int session_id2_len;
+extern Buffer loginmsg;
+
+/* methods */
+
+extern Authmethod method_none;
+extern Authmethod method_pubkey;
+extern Authmethod method_passwd;
+extern Authmethod method_kbdint;
+extern Authmethod method_hostbased;
+#ifdef GSSAPI
+extern Authmethod method_gssapi;
+#endif
+#ifdef JPAKE
+extern Authmethod method_jpake;
+#endif
-/* protocol */
+Authmethod *authmethods[] = {
+ &method_none,
+ &method_pubkey,
+#ifdef GSSAPI
+ &method_gssapi,
+#endif
+#ifdef JPAKE
+ &method_jpake,
+#endif
+ &method_passwd,
+ &method_kbdint,
+ &method_hostbased,
+ NULL
+};
-void input_service_request(int type, int plen);
-void input_userauth_request(int type, int plen);
-void protocol_error(int type, int plen);
+/* protocol */
-/* auth */
-int ssh2_auth_none(struct passwd *pw);
-int ssh2_auth_password(struct passwd *pw);
-int ssh2_auth_pubkey(struct passwd *pw, unsigned char *raw, unsigned int rlen);
+static void input_service_request(int, u_int32_t, void *);
+static void input_userauth_request(int, u_int32_t, void *);
/* helper */
-struct passwd* auth_set_user(char *u, char *s);
-int user_dsa_key_allowed(struct passwd *pw, Key *key);
-
-typedef struct Authctxt Authctxt;
-struct Authctxt {
- char *user;
- char *service;
- struct passwd pw;
- int valid;
-};
-static Authctxt *authctxt = NULL;
-static int userauth_success = 0;
-
-/*
- * loop until userauth_success == TRUE
- */
+static Authmethod *authmethod_lookup(const char *);
+static char *authmethods_get(void);
-void
-do_authentication2()
+char *
+auth2_read_banner(void)
{
- /* turn off skey/kerberos, not supported by SSH2 */
-#ifdef SKEY
- options.skey_authentication = 0;
-#endif
-#ifdef KRB4
- options.kerberos_authentication = 0;
-#endif
+ struct stat st;
+ char *banner = NULL;
+ size_t len, n;
+ int fd;
+
+ if ((fd = open(options.banner, O_RDONLY)) == -1)
+ return (NULL);
+ if (fstat(fd, &st) == -1) {
+ close(fd);
+ return (NULL);
+ }
+ if (st.st_size > 1*1024*1024) {
+ close(fd);
+ return (NULL);
+ }
- dispatch_init(&protocol_error);
- dispatch_set(SSH2_MSG_SERVICE_REQUEST, &input_service_request);
- dispatch_run(DISPATCH_BLOCK, &userauth_success);
- do_authenticated2();
+ len = (size_t)st.st_size; /* truncate */
+ banner = xmalloc(len + 1);
+ n = atomicio(read, fd, banner, len);
+ close(fd);
+
+ if (n != len) {
+ xfree(banner);
+ return (NULL);
+ }
+ banner[n] = '\0';
+
+ return (banner);
}
void
-protocol_error(int type, int plen)
+userauth_send_banner(const char *msg)
{
- log("auth: protocol error: type %d plen %d", type, plen);
- packet_start(SSH2_MSG_UNIMPLEMENTED);
- packet_put_int(0);
+ if (datafellows & SSH_BUG_BANNER)
+ return;
+
+ packet_start(SSH2_MSG_USERAUTH_BANNER);
+ packet_put_cstring(msg);
+ packet_put_cstring(""); /* language, unused */
packet_send();
- packet_write_wait();
+ debug("%s: sent", __func__);
}
+static void
+userauth_banner(void)
+{
+ char *banner = NULL;
+
+ if (options.banner == NULL ||
+ strcasecmp(options.banner, "none") == 0 ||
+ (datafellows & SSH_BUG_BANNER) != 0)
+ return;
+
+ if ((banner = PRIVSEP(auth2_read_banner())) == NULL)
+ goto done;
+ userauth_send_banner(banner);
+
+done:
+ if (banner)
+ xfree(banner);
+}
+
+/*
+ * loop until authctxt->success == TRUE
+ */
void
-input_service_request(int type, int plen)
+do_authentication2(Authctxt *authctxt)
+{
+ dispatch_init(&dispatch_protocol_error);
+ dispatch_set(SSH2_MSG_SERVICE_REQUEST, &input_service_request);
+ dispatch_run(DISPATCH_BLOCK, &authctxt->success, authctxt);
+}
+
+/*ARGSUSED*/
+static void
+input_service_request(int type, u_int32_t seq, void *ctxt)
{
- unsigned int len;
- int accept = 0;
+ Authctxt *authctxt = ctxt;
+ u_int len;
+ int acceptit = 0;
char *service = packet_get_string(&len);
- packet_done();
+ packet_check_eom();
+
+ if (authctxt == NULL)
+ fatal("input_service_request: no authctxt");
if (strcmp(service, "ssh-userauth") == 0) {
- if (!userauth_success) {
- accept = 1;
+ if (!authctxt->success) {
+ acceptit = 1;
/* now we can handle user-auth requests */
dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &input_userauth_request);
}
}
/* XXX all other service requests are denied */
- if (accept) {
+ if (acceptit) {
packet_start(SSH2_MSG_SERVICE_ACCEPT);
packet_put_cstring(service);
packet_send();
xfree(service);
}
-void
-input_userauth_request(int type, int plen)
+/*ARGSUSED*/
+static void
+input_userauth_request(int type, u_int32_t seq, void *ctxt)
{
- static void (*authlog) (const char *fmt,...) = verbose;
- static int attempt = 0;
- unsigned int len, rlen;
+ Authctxt *authctxt = ctxt;
+ Authmethod *m = NULL;
+ char *user, *service, *method, *style = NULL;
int authenticated = 0;
- char *raw, *user, *service, *method, *authmsg = NULL;
- struct passwd *pw;
-
- if (++attempt == AUTH_FAIL_MAX)
- packet_disconnect("too many failed userauth_requests");
-
- raw = packet_get_raw(&rlen);
- if (plen != rlen)
- fatal("plen != rlen");
- user = packet_get_string(&len);
- service = packet_get_string(&len);
- method = packet_get_string(&len);
- debug("userauth-request for user %s service %s method %s", user, service, method);
- /* XXX we only allow the ssh-connection service */
- pw = auth_set_user(user, service);
- if (pw && strcmp(service, "ssh-connection")==0) {
- if (strcmp(method, "none") == 0) {
- authenticated = ssh2_auth_none(pw);
- } else if (strcmp(method, "password") == 0) {
- authenticated = ssh2_auth_password(pw);
- } else if (strcmp(method, "publickey") == 0) {
- authenticated = ssh2_auth_pubkey(pw, raw, rlen);
+ if (authctxt == NULL)
+ fatal("input_userauth_request: no authctxt");
+
+ user = packet_get_string(NULL);
+ service = packet_get_string(NULL);
+ method = packet_get_string(NULL);
+ debug("userauth-request for user %s service %s method %s", user, service, method);
+ debug("attempt %d failures %d", authctxt->attempt, authctxt->failures);
+
+ if ((style = strchr(user, ':')) != NULL)
+ *style++ = 0;
+
+ if (authctxt->attempt++ == 0) {
+ /* setup auth context */
+ authctxt->pw = PRIVSEP(getpwnamallow(user));
+ authctxt->user = xstrdup(user);
+ if (authctxt->pw && strcmp(service, "ssh-connection")==0) {
+ authctxt->valid = 1;
+ debug2("input_userauth_request: setting up authctxt for %s", user);
+ } else {
+ logit("input_userauth_request: invalid user %s", user);
+ authctxt->pw = fakepw();
+#ifdef SSH_AUDIT_EVENTS
+ PRIVSEP(audit_event(SSH_INVALID_USER));
+#endif
}
+#ifdef USE_PAM
+ if (options.use_pam)
+ PRIVSEP(start_pam(authctxt));
+#endif
+ setproctitle("%s%s", authctxt->valid ? user : "unknown",
+ use_privsep ? " [net]" : "");
+ authctxt->service = xstrdup(service);
+ authctxt->style = style ? xstrdup(style) : NULL;
+ if (use_privsep)
+ mm_inform_authserv(service, style);
+ userauth_banner();
+ } else if (strcmp(user, authctxt->user) != 0 ||
+ strcmp(service, authctxt->service) != 0) {
+ packet_disconnect("Change of username or service not allowed: "
+ "(%s,%s) -> (%s,%s)",
+ authctxt->user, authctxt->service, user, service);
}
- if (authenticated && pw && pw->pw_uid == 0 && !options.permit_root_login) {
- authenticated = 0;
- log("ROOT LOGIN REFUSED FROM %.200s",
- get_canonical_hostname());
- }
+ /* reset state */
+ auth2_challenge_stop(authctxt);
+#ifdef JPAKE
+ auth2_jpake_stop(authctxt);
+#endif
-#ifdef USE_PAM
- if (authenticated && !do_pam_account(pw->pw_name, NULL))
- authenticated = 0;
-#endif /* USE_PAM */
+#ifdef GSSAPI
+ /* XXX move to auth2_gssapi_stop() */
+ dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
+ dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL);
+#endif
- /* XXX todo: check if multiple auth methods are needed */
- if (authenticated == 1) {
- authmsg = "Accepted";
- /* turn off userauth */
- dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &protocol_error);
- packet_start(SSH2_MSG_USERAUTH_SUCCESS);
- packet_send();
- packet_write_wait();
- /* now we can break out */
- userauth_success = 1;
- } else if (authenticated == 0) {
- authmsg = "Failed";
- packet_start(SSH2_MSG_USERAUTH_FAILURE);
- packet_put_cstring("publickey,password"); /* XXX dynamic */
- packet_put_char(0); /* XXX partial success, unused */
- packet_send();
- packet_write_wait();
- } else {
- authmsg = "Postponed";
+ authctxt->postponed = 0;
+
+ /* try to authenticate user */
+ m = authmethod_lookup(method);
+ if (m != NULL && authctxt->failures < options.max_authtries) {
+ debug2("input_userauth_request: try method %s", method);
+ authenticated = m->userauth(authctxt);
}
- /* Raise logging level */
- if (authenticated == 1||
- attempt == AUTH_FAIL_LOG ||
- strcmp(method, "password") == 0)
- authlog = log;
-
- authlog("%s %s for %.200s from %.200s port %d ssh2",
- authmsg,
- method,
- pw && pw->pw_uid == 0 ? "ROOT" : user,
- get_remote_ipaddr(),
- get_remote_port());
+ userauth_finish(authctxt, authenticated, method);
xfree(service);
xfree(user);
xfree(method);
}
-int
-ssh2_auth_none(struct passwd *pw)
-{
- packet_done();
-#ifdef USE_PAM
- return auth_pam_password(pw, "");
-#else /* USE_PAM */
- return auth_password(pw, "");
-#endif /* USE_PAM */
-}
-int
-ssh2_auth_password(struct passwd *pw)
-{
- char *password;
- int authenticated = 0;
- int change;
- unsigned int len;
- change = packet_get_char();
- if (change)
- log("password change not supported");
- password = packet_get_string(&len);
- packet_done();
- if (options.password_authentication &&
-#ifdef USE_PAM
- auth_pam_password(pw, password) == 1)
-#else /* USE_PAM */
- auth_password(pw, password) == 1)
-#endif /* USE_PAM */
- authenticated = 1;
- memset(password, 0, len);
- xfree(password);
- return authenticated;
-}
-int
-ssh2_auth_pubkey(struct passwd *pw, unsigned char *raw, unsigned int rlen)
+void
+userauth_finish(Authctxt *authctxt, int authenticated, char *method)
{
- Buffer b;
- Key *key;
- char *pkalg, *pkblob, *sig;
- unsigned int alen, blen, slen;
- int have_sig;
- int authenticated = 0;
+ char *methods;
- if (options.rsa_authentication == 0) {
- debug("pubkey auth disabled");
- return 0;
- }
- have_sig = packet_get_char();
- pkalg = packet_get_string(&alen);
- if (strcmp(pkalg, KEX_DSS) != 0) {
- xfree(pkalg);
- log("bad pkalg %s", pkalg); /*XXX*/
- return 0;
- }
- pkblob = packet_get_string(&blen);
- key = dsa_key_from_blob(pkblob, blen);
- if (key != NULL) {
- if (have_sig) {
- sig = packet_get_string(&slen);
- packet_done();
- buffer_init(&b);
- buffer_append(&b, session_id2, session_id2_len);
- buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
- if (slen + 4 > rlen)
- fatal("bad rlen/slen");
- buffer_append(&b, raw, rlen - slen - 4);
-#ifdef DEBUG_DSS
- buffer_dump(&b);
+ if (!authctxt->valid && authenticated)
+ fatal("INTERNAL ERROR: authenticated invalid user %s",
+ authctxt->user);
+
+ /* Special handling for root */
+ if (authenticated && authctxt->pw->pw_uid == 0 &&
+ !auth_root_allowed(method)) {
+ authenticated = 0;
+#ifdef SSH_AUDIT_EVENTS
+ PRIVSEP(audit_event(SSH_LOGIN_ROOT_DENIED));
#endif
- /* test for correct signature */
- if (user_dsa_key_allowed(pw, key) &&
- dsa_verify(key, sig, slen, buffer_ptr(&b), buffer_len(&b)) == 1)
- authenticated = 1;
- buffer_clear(&b);
- xfree(sig);
- } else {
- packet_done();
- debug("test key...");
- /* test whether pkalg/pkblob are acceptable */
- /* XXX fake reply and always send PK_OK ? */
- if (user_dsa_key_allowed(pw, key)) {
- packet_start(SSH2_MSG_USERAUTH_PK_OK);
- packet_put_string(pkalg, alen);
- packet_put_string(pkblob, blen);
- packet_send();
+ }
+
+#ifdef USE_PAM
+ if (options.use_pam && authenticated) {
+ if (!PRIVSEP(do_pam_account())) {
+ /* if PAM returned a message, send it to the user */
+ if (buffer_len(&loginmsg) > 0) {
+ buffer_append(&loginmsg, "\0", 1);
+ userauth_send_banner(buffer_ptr(&loginmsg));
packet_write_wait();
- authenticated = -1;
}
+ fatal("Access denied for user %s by PAM account "
+ "configuration", authctxt->user);
}
- key_free(key);
}
- xfree(pkalg);
- xfree(pkblob);
- return authenticated;
-}
+#endif
-/* set and get current user */
+#ifdef _UNICOS
+ if (authenticated && cray_access_denied(authctxt->user)) {
+ authenticated = 0;
+ fatal("Access denied for user %s.",authctxt->user);
+ }
+#endif /* _UNICOS */
-struct passwd*
-auth_get_user(void)
-{
- return (authctxt != NULL && authctxt->valid) ? &authctxt->pw : NULL;
-}
+ /* Log before sending the reply */
+ auth_log(authctxt, authenticated, method, " ssh2");
-struct passwd*
-auth_set_user(char *u, char *s)
-{
- struct passwd *pw, *copy;
-
- if (authctxt == NULL) {
- authctxt = xmalloc(sizeof(*authctxt));
- authctxt->valid = 0;
- authctxt->user = xstrdup(u);
- authctxt->service = xstrdup(s);
- setproctitle("%s", u);
- pw = getpwnam(u);
- if (!pw || !allowed_user(pw)) {
- log("auth_set_user: illegal user %s", u);
- return NULL;
- }
-#ifdef USE_PAM
- start_pam(pw);
-#endif
- copy = &authctxt->pw;
- memset(copy, 0, sizeof(*copy));
- copy->pw_name = xstrdup(pw->pw_name);
- copy->pw_passwd = xstrdup(pw->pw_passwd);
- copy->pw_uid = pw->pw_uid;
- copy->pw_gid = pw->pw_gid;
- copy->pw_dir = xstrdup(pw->pw_dir);
- copy->pw_shell = xstrdup(pw->pw_shell);
- authctxt->valid = 1;
+ if (authctxt->postponed)
+ return;
+
+ /* XXX todo: check if multiple auth methods are needed */
+ if (authenticated == 1) {
+ /* turn off userauth */
+ dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &dispatch_protocol_ignore);
+ packet_start(SSH2_MSG_USERAUTH_SUCCESS);
+ packet_send();
+ packet_write_wait();
+ /* now we can break out */
+ authctxt->success = 1;
} else {
- if (strcmp(u, authctxt->user) != 0 ||
- strcmp(s, authctxt->service) != 0) {
- log("auth_set_user: missmatch: (%s,%s)!=(%s,%s)",
- u, s, authctxt->user, authctxt->service);
- return NULL;
+
+ /* Allow initial try of "none" auth without failure penalty */
+ if (authctxt->attempt > 1 || strcmp(method, "none") != 0)
+ authctxt->failures++;
+ if (authctxt->failures >= options.max_authtries) {
+#ifdef SSH_AUDIT_EVENTS
+ PRIVSEP(audit_event(SSH_LOGIN_EXCEED_MAXTRIES));
+#endif
+ packet_disconnect(AUTH_FAIL_MSG, authctxt->user);
}
+ methods = authmethods_get();
+ packet_start(SSH2_MSG_USERAUTH_FAILURE);
+ packet_put_cstring(methods);
+ packet_put_char(0); /* XXX partial success, unused */
+ packet_send();
+ packet_write_wait();
+ xfree(methods);
}
- return auth_get_user();
}
-/* return 1 if user allows given key */
-int
-user_dsa_key_allowed(struct passwd *pw, Key *key)
+static char *
+authmethods_get(void)
{
- char line[8192], file[1024];
- int found_key = 0;
- unsigned int bits = -1;
- FILE *f;
- unsigned long linenum = 0;
- struct stat st;
- Key *found;
-
- /* Temporarily use the user's uid. */
- temporarily_use_uid(pw->pw_uid);
-
- /* The authorized keys. */
- snprintf(file, sizeof file, "%.500s/%.100s", pw->pw_dir,
- SSH_USER_PERMITTED_KEYS2);
+ Buffer b;
+ char *list;
+ int i;
- /* Fail quietly if file does not exist */
- if (stat(file, &st) < 0) {
- /* Restore the privileged uid. */
- restore_uid();
- return 0;
- }
- /* Open the file containing the authorized keys. */
- f = fopen(file, "r");
- if (!f) {
- /* Restore the privileged uid. */
- restore_uid();
- return 0;
- }
- if (options.strict_modes) {
- int fail = 0;
- char buf[1024];
- /* Check open file in order to avoid open/stat races */
- if (fstat(fileno(f), &st) < 0 ||
- (st.st_uid != 0 && st.st_uid != pw->pw_uid) ||
- (st.st_mode & 022) != 0) {
- snprintf(buf, sizeof buf, "DSA authentication refused for %.100s: "
- "bad ownership or modes for '%s'.", pw->pw_name, file);
- fail = 1;
- } else {
- /* Check path to SSH_USER_PERMITTED_KEYS */
- int i;
- static const char *check[] = {
- "", SSH_USER_DIR, NULL
- };
- for (i = 0; check[i]; i++) {
- snprintf(line, sizeof line, "%.500s/%.100s",
- pw->pw_dir, check[i]);
- if (stat(line, &st) < 0 ||
- (st.st_uid != 0 && st.st_uid != pw->pw_uid) ||
- (st.st_mode & 022) != 0) {
- snprintf(buf, sizeof buf,
- "DSA authentication refused for %.100s: "
- "bad ownership or modes for '%s'.",
- pw->pw_name, line);
- fail = 1;
- break;
- }
- }
- }
- if (fail) {
- log(buf);
- fclose(f);
- restore_uid();
- return 0;
- }
- }
- found_key = 0;
- found = key_new(KEY_DSA);
-
- while (fgets(line, sizeof(line), f)) {
- char *cp;
- linenum++;
- /* Skip leading whitespace, empty and comment lines. */
- for (cp = line; *cp == ' ' || *cp == '\t'; cp++)
- ;
- if (!*cp || *cp == '\n' || *cp == '#')
+ buffer_init(&b);
+ for (i = 0; authmethods[i] != NULL; i++) {
+ if (strcmp(authmethods[i]->name, "none") == 0)
continue;
- bits = key_read(found, &cp);
- if (bits == 0)
- continue;
- if (key_equal(found, key)) {
- found_key = 1;
- debug("matching key found: file %s, line %ld",
- file, linenum);
- break;
+ if (authmethods[i]->enabled != NULL &&
+ *(authmethods[i]->enabled) != 0) {
+ if (buffer_len(&b) > 0)
+ buffer_append(&b, ",", 1);
+ buffer_append(&b, authmethods[i]->name,
+ strlen(authmethods[i]->name));
}
}
- restore_uid();
- fclose(f);
- key_free(found);
- return found_key;
+ buffer_append(&b, "\0", 1);
+ list = xstrdup(buffer_ptr(&b));
+ buffer_free(&b);
+ return list;
}
+
+static Authmethod *
+authmethod_lookup(const char *name)
+{
+ int i;
+
+ if (name != NULL)
+ for (i = 0; authmethods[i] != NULL; i++)
+ if (authmethods[i]->enabled != NULL &&
+ *(authmethods[i]->enabled) != 0 &&
+ strcmp(name, authmethods[i]->name) == 0)
+ return authmethods[i];
+ debug2("Unrecognized authentication method name: %s",
+ name ? name : "NULL");
+ return NULL;
+}
+
andersk / openssh.git / blobdiff