X-Git-Url: http://andersk.mit.edu/gitweb/openssh.git/blobdiff_plain/38c295d646559d5e684af97dbdfe3378871a9081..3469eac4c175d8337b50723a86425406731a473a:/auth2.c

diff --git a/auth2.c b/auth2.c
index c7dcf195..431f955f 100644
--- a/auth2.c
+++ b/auth2.c
@@ -9,11 +9,6 @@
  * 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
@@ -26,107 +21,127 @@
  * (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 1.10 2000/06/18 04:05:02 markus Exp $");
+RCSID("$OpenBSD: auth2.c,v 1.82 2002/01/13 17:57:37 markus Exp $");
 
-#include <openssl/dsa.h>
-#include <openssl/rsa.h>
 #include <openssl/evp.h>
 
+#include "ssh2.h"
 #include "xmalloc.h"
 #include "rsa.h"
-#include "ssh.h"
-#include "pty.h"
+#include "sshpty.h"
 #include "packet.h"
 #include "buffer.h"
-#include "cipher.h"
+#include "log.h"
 #include "servconf.h"
 #include "compat.h"
 #include "channels.h"
 #include "bufaux.h"
-#include "ssh2.h"
 #include "auth.h"
 #include "session.h"
 #include "dispatch.h"
-#include "auth.h"
 #include "key.h"
+#include "cipher.h"
 #include "kex.h"
-
-#include "dsa.h"
+#include "pathnames.h"
 #include "uidswap.h"
 #include "auth-options.h"
+#include "misc.h"
+#include "hostfile.h"
+#include "canohost.h"
+#include "match.h"
 
 /* import */
 extern ServerOptions options;
-extern unsigned char *session_id2;
+extern u_char *session_id2;
 extern int session_id2_len;
 
-/* protocol */
+static Authctxt	*x_authctxt = NULL;
+static int one = 1;
 
-void	input_service_request(int type, int plen);
-void	input_userauth_request(int type, int plen);
-void	protocol_error(int type, int plen);
+typedef struct Authmethod Authmethod;
+struct Authmethod {
+	char	*name;
+	int	(*userauth)(Authctxt *authctxt);
+	int	*enabled;
+};
 
-/* auth */
-int	ssh2_auth_none(struct passwd *pw);
-int	ssh2_auth_password(struct passwd *pw);
-int  	ssh2_auth_pubkey(struct passwd *pw, char *service);
+/* protocol */
+
+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 Authmethod *authmethod_lookup(const char *);
+static char *authmethods_get(void);
+static int user_key_allowed(struct passwd *, Key *);
+static int hostbased_key_allowed(struct passwd *, const char *, char *, Key *);
+
+/* auth */
+static void userauth_banner(void);
+static int userauth_none(Authctxt *);
+static int userauth_passwd(Authctxt *);
+static int userauth_pubkey(Authctxt *);
+static int userauth_hostbased(Authctxt *);
+static int userauth_kbdint(Authctxt *);
+
+Authmethod authmethods[] = {
+	{"none",
+		userauth_none,
+		&one},
+	{"publickey",
+		userauth_pubkey,
+		&options.pubkey_authentication},
+	{"password",
+		userauth_passwd,
+		&options.password_authentication},
+	{"keyboard-interactive",
+		userauth_kbdint,
+		&options.kbd_interactive_authentication},
+	{"hostbased",
+		userauth_hostbased,
+		&options.hostbased_authentication},
+	{NULL, NULL, NULL}
 };
-static Authctxt	*authctxt = NULL;
-static int userauth_success = 0;
 
 /*
- * loop until userauth_success == TRUE
+ * loop until authctxt->success == TRUE
  */
 
 void
-do_authentication2()
+do_authentication2(void)
 {
-	/* turn off skey/kerberos, not supported by SSH2 */
-#ifdef SKEY
-	options.skey_authentication = 0;
-#endif
-#ifdef KRB4
-	options.kerberos_authentication = 0;
-#endif
+	Authctxt *authctxt = authctxt_new();
 
-	dispatch_init(&protocol_error);
-	dispatch_set(SSH2_MSG_SERVICE_REQUEST, &input_service_request);
-	dispatch_run(DISPATCH_BLOCK, &userauth_success);
-	do_authenticated2();
-}
+	x_authctxt = authctxt;		/*XXX*/
 
-void
-protocol_error(int type, int plen)
-{
-	log("auth: protocol error: type %d plen %d", type, plen);
-	packet_start(SSH2_MSG_UNIMPLEMENTED);
-	packet_put_int(0);
-	packet_send();
-	packet_write_wait();
+	/* challenge-response is implemented via keyboard interactive */
+	if (options.challenge_response_authentication)
+		options.kbd_interactive_authentication = 1;
+	if (options.pam_authentication_via_kbd_int)
+		options.kbd_interactive_authentication = 1;
+
+	dispatch_init(&dispatch_protocol_error);
+	dispatch_set(SSH2_MSG_SERVICE_REQUEST, &input_service_request);
+	dispatch_run(DISPATCH_BLOCK, &authctxt->success, authctxt);
+	do_authenticated(authctxt);
 }
 
-void
-input_service_request(int type, int plen)
+static void
+input_service_request(int type, u_int32_t seq, void *ctxt)
 {
-	unsigned int len;
+	Authctxt *authctxt = ctxt;
+	u_int len;
 	int accept = 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) {
+		if (!authctxt->success) {
 			accept = 1;
 			/* now we can handle user-auth requests */
 			dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &input_userauth_request);
@@ -146,188 +161,313 @@ input_service_request(int type, int plen)
 	xfree(service);
 }
 
-void
-input_userauth_request(int type, int plen)
+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;
+	Authctxt *authctxt = ctxt;
+	Authmethod *m = NULL;
+	char *user, *service, *method, *style = NULL;
 	int authenticated = 0;
-	char *user, *service, *method, *authmsg = NULL;
-	struct passwd *pw;
-#ifdef WITH_AIXAUTHENTICATE
-	extern char *aixloginmsg;
-#endif /* WITH_AIXAUTHENTICATE */
 
-	user = packet_get_string(&len);
-	service = packet_get_string(&len);
-	method = packet_get_string(&len);
-	if (++attempt == AUTH_FAIL_MAX) {
-#ifdef WITH_AIXAUTHENTICATE 
-		loginfailed(user,get_canonical_hostname(),"ssh");
-#endif /* WITH_AIXAUTHENTICATE */
-		packet_disconnect("too many failed userauth_requests");
-	}
-	debug("userauth-request for user %s service %s method %s", user, service, method);
+	if (authctxt == NULL)
+		fatal("input_userauth_request: no authctxt");
 
-	/* 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, service);
+	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 */
+		struct passwd *pw = NULL;
+		pw = getpwnam(user);
+		if (pw && allowed_user(pw) && strcmp(service, "ssh-connection")==0) {
+			authctxt->pw = pwcopy(pw);
+			authctxt->valid = 1;
+			debug2("input_userauth_request: setting up authctxt for %s", user);
+#ifdef USE_PAM
+			start_pam(pw->pw_name);
+#endif
+		} else {
+			log("input_userauth_request: illegal user %s", user);
+#ifdef USE_PAM
+			start_pam("NOUSER");
+#endif
 		}
+		setproctitle("%s", pw ? user : "unknown");
+		authctxt->user = xstrdup(user);
+		authctxt->service = xstrdup(service);
+		authctxt->style = style ? xstrdup(style) : NULL;
+	} 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);
+	authctxt->postponed = 0;
+
+	/* try to authenticate user */
+	m = authmethod_lookup(method);
+	if (m != NULL) {
+		debug2("input_userauth_request: try method %s", method);
+		authenticated =	m->userauth(authctxt);
 	}
+	userauth_finish(authctxt, authenticated, method);
+
+	xfree(service);
+	xfree(user);
+	xfree(method);
+}
+
+void
+userauth_finish(Authctxt *authctxt, int authenticated, char *method)
+{
+	char *methods;
+
+	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 USE_PAM
-		if (authenticated && !do_pam_account(pw->pw_name, NULL))
-			authenticated = 0;
+	if (authenticated && authctxt->user && !do_pam_account(authctxt->user,
+	    NULL))
+		authenticated = 0;
 #endif /* USE_PAM */
 
-	/* Raise logging level */
-	if (authenticated == 1 ||
-	    attempt == AUTH_FAIL_LOG ||
-	    strcmp(method, "password") == 0)
-		authlog = log;
-
 	/* Log before sending the reply */
-	if (authenticated == 1) {
-		authmsg = "Accepted";
-	} else if (authenticated == 0) {
-		authmsg = "Failed";
-	} else {
-		authmsg = "Postponed";
-	}
-	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());
+	auth_log(authctxt, authenticated, method, " ssh2");
+
+	if (authctxt->postponed)
+		return;
 
 	/* XXX todo: check if multiple auth methods are needed */
 	if (authenticated == 1) {
-#ifdef WITH_AIXAUTHENTICATE
-		/* We don't have a pty yet, so just label the line as "ssh" */
-		if (loginsuccess(user,get_canonical_hostname(),"ssh",
-				&aixloginmsg) < 0)
-			aixloginmsg = NULL;
-#endif /* WITH_AIXAUTHENTICATE */
 		/* turn off userauth */
-		dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &protocol_error);
+		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 */
-		userauth_success = 1;
-	} else if (authenticated == 0) {
+		authctxt->success = 1;
+	} else {
+		if (authctxt->failures++ > AUTH_FAIL_MAX) {
+#ifdef WITH_AIXAUTHENTICATE
+			loginfailed(authctxt->user,
+			    get_canonical_hostname(options.reverse_mapping_check),
+			    "ssh");
+#endif /* WITH_AIXAUTHENTICATE */
+			packet_disconnect(AUTH_FAIL_MSG, authctxt->user);
+		}
+		methods = authmethods_get();
 		packet_start(SSH2_MSG_USERAUTH_FAILURE);
-		packet_put_cstring("publickey,password");	/* XXX dynamic */
-		packet_put_char(0);				/* XXX partial success, unused */
+		packet_put_cstring(methods);
+		packet_put_char(0);	/* XXX partial success, unused */
 		packet_send();
 		packet_write_wait();
+		xfree(methods);
 	}
+}
 
-	xfree(service);
-	xfree(user);
-	xfree(method);
+static void
+userauth_banner(void)
+{
+	struct stat st;
+	char *banner = NULL;
+	off_t len, n;
+	int fd;
+
+	if (options.banner == NULL || (datafellows & SSH_BUG_BANNER))
+		return;
+	if ((fd = open(options.banner, O_RDONLY)) < 0)
+		return;
+	if (fstat(fd, &st) < 0)
+		goto done;
+	len = st.st_size;
+	banner = xmalloc(len + 1);
+	if ((n = read(fd, banner, len)) < 0)
+		goto done;
+	banner[n] = '\0';
+	packet_start(SSH2_MSG_USERAUTH_BANNER);
+	packet_put_cstring(banner);
+	packet_put_cstring("");		/* language, unused */
+	packet_send();
+	debug("userauth_banner: sent");
+done:
+	if (banner)
+		xfree(banner);
+	close(fd);
+	return;
 }
 
-int
-ssh2_auth_none(struct passwd *pw)
+static int
+userauth_none(Authctxt *authctxt)
 {
-	packet_done();
+	/* disable method "none", only allowed one time */
+	Authmethod *m = authmethod_lookup("none");
+	if (m != NULL)
+		m->enabled = NULL;
+	packet_check_eom();
+	userauth_banner();
+
+	if (authctxt->valid == 0)
+		return(0);
+
+#ifdef HAVE_CYGWIN
+	if (check_nt_auth(1, authctxt->pw) == 0)
+		return(0);
+#endif
 #ifdef USE_PAM
-	return auth_pam_password(pw, "");
-#else /* USE_PAM */
-	return auth_password(pw, "");
+	return auth_pam_password(authctxt->pw, "");
+#elif defined(HAVE_OSF_SIA)
+	return 0;
+#else /* !HAVE_OSF_SIA && !USE_PAM */
+	return auth_password(authctxt, "");
 #endif /* USE_PAM */
 }
-int
-ssh2_auth_password(struct passwd *pw)
+
+static int
+userauth_passwd(Authctxt *authctxt)
 {
 	char *password;
 	int authenticated = 0;
 	int change;
-	unsigned int len;
+	u_int len;
 	change = packet_get_char();
 	if (change)
 		log("password change not supported");
 	password = packet_get_string(&len);
-	packet_done();
-	if (options.password_authentication &&
+	packet_check_eom();
+	if (authctxt->valid &&
+#ifdef HAVE_CYGWIN
+	    check_nt_auth(1, authctxt->pw) &&
+#endif
 #ifdef USE_PAM
-	    auth_pam_password(pw, password) == 1)
-#else /* USE_PAM */
-	    auth_password(pw, password) == 1)
+	    auth_pam_password(authctxt->pw, password) == 1)
+#elif defined(HAVE_OSF_SIA)
+	    auth_sia_password(authctxt->user, password) == 1)
+#else /* !USE_PAM && !HAVE_OSF_SIA */
+	    auth_password(authctxt, password) == 1)
 #endif /* USE_PAM */
 		authenticated = 1;
 	memset(password, 0, len);
 	xfree(password);
 	return authenticated;
 }
-int
-ssh2_auth_pubkey(struct passwd *pw, char *service)
+
+static int
+userauth_kbdint(Authctxt *authctxt)
+{
+	int authenticated = 0;
+	char *lang, *devs;
+
+	lang = packet_get_string(NULL);
+	devs = packet_get_string(NULL);
+	packet_check_eom();
+
+	debug("keyboard-interactive devs %s", devs);
+
+	if (options.challenge_response_authentication)
+		authenticated = auth2_challenge(authctxt, devs);
+
+#ifdef USE_PAM
+	if (authenticated == 0 && options.pam_authentication_via_kbd_int)
+		authenticated = auth2_pam(authctxt);
+#endif
+	xfree(devs);
+	xfree(lang);
+#ifdef HAVE_CYGWIN
+	if (check_nt_auth(0, authctxt->pw) == 0)
+		return(0);
+#endif
+	return authenticated;
+}
+
+static int
+userauth_pubkey(Authctxt *authctxt)
 {
 	Buffer b;
 	Key *key;
 	char *pkalg, *pkblob, *sig;
-	unsigned int alen, blen, slen;
-	int have_sig;
+	u_int alen, blen, slen;
+	int have_sig, pktype;
 	int authenticated = 0;
 
-	if (options.dsa_authentication == 0) {
-		debug("pubkey auth disabled");
+	if (!authctxt->valid) {
+		debug2("userauth_pubkey: disabled because of invalid user");
 		return 0;
 	}
 	have_sig = packet_get_char();
-	pkalg = packet_get_string(&alen);
-	if (strcmp(pkalg, KEX_DSS) != 0) {
+	if (datafellows & SSH_BUG_PKAUTH) {
+		debug2("userauth_pubkey: SSH_BUG_PKAUTH");
+		/* no explicit pkalg given */
+		pkblob = packet_get_string(&blen);
+		buffer_init(&b);
+		buffer_append(&b, pkblob, blen);
+		/* so we have to extract the pkalg from the pkblob */
+		pkalg = buffer_get_string(&b, &alen);
+		buffer_free(&b);
+	} else {
+		pkalg = packet_get_string(&alen);
+		pkblob = packet_get_string(&blen);
+	}
+	pktype = key_type_from_name(pkalg);
+	if (pktype == KEY_UNSPEC) {
+		/* this is perfectly legal */
+		log("userauth_pubkey: unsupported public key algorithm: %s", pkalg);
 		xfree(pkalg);
-		log("bad pkalg %s", pkalg);	/*XXX*/
+		xfree(pkblob);
 		return 0;
 	}
-	pkblob = packet_get_string(&blen);
-	key = dsa_key_from_blob(pkblob, blen);
+	key = key_from_blob(pkblob, blen);
 	if (key != NULL) {
 		if (have_sig) {
 			sig = packet_get_string(&slen);
-			packet_done();
+			packet_check_eom();
 			buffer_init(&b);
-			buffer_append(&b, session_id2, session_id2_len);
-
+			if (datafellows & SSH_OLD_SESSIONID) {
+				buffer_append(&b, session_id2, session_id2_len);
+			} else {
+				buffer_put_string(&b, session_id2, session_id2_len);
+			}
 			/* reconstruct packet */
 			buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
-			buffer_put_cstring(&b, pw->pw_name);
+			buffer_put_cstring(&b, authctxt->user);
 			buffer_put_cstring(&b,
-			    datafellows & SSH_BUG_PUBKEYAUTH ?
+			    datafellows & SSH_BUG_PKSERVICE ?
 			    "ssh-userauth" :
-			    service);
-			buffer_put_cstring(&b, "publickey");
-			buffer_put_char(&b, have_sig);
-			buffer_put_cstring(&b, KEX_DSS);
+			    authctxt->service);
+			if (datafellows & SSH_BUG_PKAUTH) {
+				buffer_put_char(&b, have_sig);
+			} else {
+				buffer_put_cstring(&b, "publickey");
+				buffer_put_char(&b, have_sig);
+				buffer_put_cstring(&b, pkalg);
+			}
 			buffer_put_string(&b, pkblob, blen);
-#ifdef DEBUG_DSS
+#ifdef DEBUG_PK
 			buffer_dump(&b);
 #endif
 			/* test for correct signature */
-			if (user_dsa_key_allowed(pw, key) &&
-			    dsa_verify(key, sig, slen, buffer_ptr(&b), buffer_len(&b)) == 1)
+			if (user_key_allowed(authctxt->pw, key) &&
+			    key_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 */
+			debug("test whether pkalg/pkblob are acceptable");
+			packet_check_eom();
+
 			/* XXX fake reply and always send PK_OK ? */
 			/*
 			 * XXX this allows testing whether a user is allowed
@@ -336,87 +476,170 @@ ssh2_auth_pubkey(struct passwd *pw, char *service)
 			 * if a user is not allowed to login. is this an
 			 * issue? -markus
 			 */
-			if (user_dsa_key_allowed(pw, key)) {
+			if (user_key_allowed(authctxt->pw, key)) {
 				packet_start(SSH2_MSG_USERAUTH_PK_OK);
 				packet_put_string(pkalg, alen);
 				packet_put_string(pkblob, blen);
 				packet_send();
 				packet_write_wait();
-				authenticated = -1;
+				authctxt->postponed = 1;
 			}
 		}
+		if (authenticated != 1)
+			auth_clear_options();
 		key_free(key);
 	}
+	debug2("userauth_pubkey: authenticated %d pkalg %s", authenticated, pkalg);
 	xfree(pkalg);
 	xfree(pkblob);
+#ifdef HAVE_CYGWIN
+	if (check_nt_auth(0, authctxt->pw) == 0)
+		return(0);
+#endif
 	return authenticated;
 }
 
-/* set and get current user */
+static int
+userauth_hostbased(Authctxt *authctxt)
+{
+	Buffer b;
+	Key *key;
+	char *pkalg, *pkblob, *sig, *cuser, *chost, *service;
+	u_int alen, blen, slen;
+	int pktype;
+	int authenticated = 0;
+
+	if (!authctxt->valid) {
+		debug2("userauth_hostbased: disabled because of invalid user");
+		return 0;
+	}
+	pkalg = packet_get_string(&alen);
+	pkblob = packet_get_string(&blen);
+	chost = packet_get_string(NULL);
+	cuser = packet_get_string(NULL);
+	sig = packet_get_string(&slen);
+
+	debug("userauth_hostbased: cuser %s chost %s pkalg %s slen %d",
+	    cuser, chost, pkalg, slen);
+#ifdef DEBUG_PK
+	debug("signature:");
+	buffer_init(&b);
+	buffer_append(&b, sig, slen);
+	buffer_dump(&b);
+	buffer_free(&b);
+#endif
+	pktype = key_type_from_name(pkalg);
+	if (pktype == KEY_UNSPEC) {
+		/* this is perfectly legal */
+		log("userauth_hostbased: unsupported "
+		    "public key algorithm: %s", pkalg);
+		goto done;
+	}
+	key = key_from_blob(pkblob, blen);
+	if (key == NULL) {
+		debug("userauth_hostbased: cannot decode key: %s", pkalg);
+		goto done;
+	}
+	service = datafellows & SSH_BUG_HBSERVICE ? "ssh-userauth" :
+	    authctxt->service;
+	buffer_init(&b);
+	buffer_put_string(&b, session_id2, session_id2_len);
+	/* reconstruct packet */
+	buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
+	buffer_put_cstring(&b, authctxt->user);
+	buffer_put_cstring(&b, service);
+	buffer_put_cstring(&b, "hostbased");
+	buffer_put_string(&b, pkalg, alen);
+	buffer_put_string(&b, pkblob, blen);
+	buffer_put_cstring(&b, chost);
+	buffer_put_cstring(&b, cuser);
+#ifdef DEBUG_PK
+	buffer_dump(&b);
+#endif
+	/* test for allowed key and correct signature */
+	if (hostbased_key_allowed(authctxt->pw, cuser, chost, key) &&
+	    key_verify(key, sig, slen, buffer_ptr(&b), buffer_len(&b)) == 1)
+		authenticated = 1;
+
+	buffer_clear(&b);
+	key_free(key);
+
+done:
+	debug2("userauth_hostbased: authenticated %d", authenticated);
+	xfree(pkalg);
+	xfree(pkblob);
+	xfree(cuser);
+	xfree(chost);
+	xfree(sig);
+	return authenticated;
+}
+
+/* get current user */
 
 struct passwd*
 auth_get_user(void)
 {
-	return (authctxt != NULL && authctxt->valid) ? &authctxt->pw : NULL;
+	return (x_authctxt != NULL && x_authctxt->valid) ? x_authctxt->pw : NULL;
 }
 
-struct passwd*
-auth_set_user(char *u, char *s)
+#define	DELIM	","
+
+static char *
+authmethods_get(void)
 {
-	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;
-	} 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;
+	Authmethod *method = NULL;
+	Buffer b;
+	char *list;
+
+	buffer_init(&b);
+	for (method = authmethods; method->name != NULL; method++) {
+		if (strcmp(method->name, "none") == 0)
+			continue;
+		if (method->enabled != NULL && *(method->enabled) != 0) {
+			if (buffer_len(&b) > 0)
+				buffer_append(&b, ",", 1);
+			buffer_append(&b, method->name, strlen(method->name));
 		}
 	}
-	return auth_get_user();
+	buffer_append(&b, "\0", 1);
+	list = xstrdup(buffer_ptr(&b));
+	buffer_free(&b);
+	return list;
+}
+
+static Authmethod *
+authmethod_lookup(const char *name)
+{
+	Authmethod *method = NULL;
+	if (name != NULL)
+		for (method = authmethods; method->name != NULL; method++)
+			if (method->enabled != NULL &&
+			    *(method->enabled) != 0 &&
+			    strcmp(name, method->name) == 0)
+				return method;
+	debug2("Unrecognized authentication method name: %s", name ? name : "NULL");
+	return NULL;
 }
 
 /* return 1 if user allows given key */
-int
-user_dsa_key_allowed(struct passwd *pw, Key *key)
+static int
+user_key_allowed2(struct passwd *pw, Key *key, char *file)
 {
-	char line[8192], file[1024];
+	char line[8192];
 	int found_key = 0;
-	unsigned int bits = -1;
 	FILE *f;
-	unsigned long linenum = 0;
+	u_long linenum = 0;
 	struct stat st;
 	Key *found;
+	char *fp;
+
+	if (pw == NULL)
+		return 0;
 
 	/* Temporarily use the user's uid. */
-	temporarily_use_uid(pw->pw_uid);
+	temporarily_use_uid(pw);
 
-	/* The authorized keys. */
-	snprintf(file, sizeof file, "%.500s/%.100s", pw->pw_dir,
-	    SSH_USER_PERMITTED_KEYS2);
+	debug("trying public key file %s", file);
 
 	/* Fail quietly if file does not exist */
 	if (stat(file, &st) < 0) {
@@ -431,46 +654,16 @@ user_dsa_key_allowed(struct passwd *pw, Key *key)
 		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;
-		}
+	if (options.strict_modes &&
+	    secure_filename(f, file, pw, line, sizeof(line)) != 0) {
+		fclose(f);
+		log("Authentication refused: %s", line);
+		restore_uid();
+		return 0;
 	}
+
 	found_key = 0;
-	found = key_new(KEY_DSA);
+	found = key_new(key->type);
 
 	while (fgets(line, sizeof(line), f)) {
 		char *cp, *options = NULL;
@@ -481,10 +674,10 @@ user_dsa_key_allowed(struct passwd *pw, Key *key)
 		if (!*cp || *cp == '\n' || *cp == '#')
 			continue;
 
-		bits = key_read(found, &cp);
-		if (bits == 0) {
+		if (key_read(found, &cp) != 1) {
 			/* no key?  check if there are options for this key */
 			int quoted = 0;
+			debug2("user_key_allowed: check options: '%s'", cp);
 			options = cp;
 			for (; *cp && (quoted || (*cp != ' ' && *cp != '\t')); cp++) {
 				if (*cp == '\\' && cp[1] == '"')
@@ -495,22 +688,97 @@ user_dsa_key_allowed(struct passwd *pw, Key *key)
 			/* Skip remaining whitespace. */
 			for (; *cp == ' ' || *cp == '\t'; cp++)
 				;
-			bits = key_read(found, &cp);
-			if (bits == 0) {
+			if (key_read(found, &cp) != 1) {
+				debug2("user_key_allowed: advance: '%s'", cp);
 				/* still no key?  advance to next line*/
 				continue;
 			}
 		}
 		if (key_equal(found, key) &&
-		    auth_parse_options(pw, options, linenum) == 1) {
+		    auth_parse_options(pw, options, file, linenum) == 1) {
 			found_key = 1;
-			debug("matching key found: file %s, line %ld",
+			debug("matching key found: file %s, line %lu",
 			    file, linenum);
+			fp = key_fingerprint(found, SSH_FP_MD5, SSH_FP_HEX);
+			verbose("Found matching %s key: %s",
+			    key_type(found), fp);
+			xfree(fp);
 			break;
 		}
 	}
 	restore_uid();
 	fclose(f);
 	key_free(found);
+	if (!found_key)
+		debug2("key not found");
 	return found_key;
 }
+
+/* check whether given key is in .ssh/authorized_keys* */
+static int
+user_key_allowed(struct passwd *pw, Key *key)
+{
+	int success;
+	char *file;
+
+	file = authorized_keys_file(pw);
+	success = user_key_allowed2(pw, key, file);
+	xfree(file);
+	if (success)
+		return success;
+
+	/* try suffix "2" for backward compat, too */
+	file = authorized_keys_file2(pw);
+	success = user_key_allowed2(pw, key, file);
+	xfree(file);
+	return success;
+}
+
+/* return 1 if given hostkey is allowed */
+static int
+hostbased_key_allowed(struct passwd *pw, const char *cuser, char *chost,
+    Key *key)
+{
+	const char *resolvedname, *ipaddr, *lookup;
+	HostStatus host_status;
+	int len;
+
+	resolvedname = get_canonical_hostname(options.reverse_mapping_check);
+	ipaddr = get_remote_ipaddr();
+
+	debug2("userauth_hostbased: chost %s resolvedname %s ipaddr %s",
+	    chost, resolvedname, ipaddr);
+
+	if (options.hostbased_uses_name_from_packet_only) {
+		if (auth_rhosts2(pw, cuser, chost, chost) == 0)
+			return 0;
+		lookup = chost;
+	} else {
+		if (((len = strlen(chost)) > 0) && chost[len - 1] == '.') {
+			debug2("stripping trailing dot from chost %s", chost);
+			chost[len - 1] = '\0';
+		}
+		if (strcasecmp(resolvedname, chost) != 0)
+			log("userauth_hostbased mismatch: "
+			    "client sends %s, but we resolve %s to %s",
+			    chost, ipaddr, resolvedname);
+		if (auth_rhosts2(pw, cuser, resolvedname, ipaddr) == 0)
+			return 0;
+		lookup = resolvedname;
+	}
+	debug2("userauth_hostbased: access allowed by auth_rhosts2");
+
+	host_status = check_key_in_hostfiles(pw, key, lookup,
+	    _PATH_SSH_SYSTEM_HOSTFILE,
+	    options.ignore_user_known_hosts ? NULL : _PATH_SSH_USER_HOSTFILE);
+
+	/* backward compat if no key has been found. */
+	if (host_status == HOST_NEW)
+		host_status = check_key_in_hostfiles(pw, key, lookup,
+		    _PATH_SSH_SYSTEM_HOSTFILE2,
+		    options.ignore_user_known_hosts ? NULL :
+		    _PATH_SSH_USER_HOSTFILE2);
+
+	return (host_status == HOST_OK);
+}
+