X-Git-Url: http://andersk.mit.edu/gitweb/openssh.git/blobdiff_plain/ddcfed5711959bc4d8151bf34ef676eb257c7068..HEAD:/auth2.c

diff --git a/auth2.c b/auth2.c
index 39322dc6..5d546855 100644
--- a/auth2.c
+++ b/auth2.c
@@ -1,3 +1,4 @@
+/* $OpenBSD: auth2.c,v 1.121 2009/06/22 05:39:28 dtucker Exp $ */
 /*
  * Copyright (c) 2000 Markus Friedl.  All rights reserved.
  *
@@ -23,149 +24,180 @@
  */
 
 #include "includes.h"
-RCSID("$OpenBSD: auth2.c,v 1.70 2001/09/20 13:46:48 markus Exp $");
 
-#include <openssl/evp.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <sys/uio.h>
 
-#include "ssh2.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 "sshpty.h"
+#include "ssh2.h"
 #include "packet.h"
-#include "buffer.h"
 #include "log.h"
+#include "buffer.h"
 #include "servconf.h"
 #include "compat.h"
-#include "channels.h"
-#include "bufaux.h"
+#include "key.h"
+#include "hostfile.h"
 #include "auth.h"
-#include "session.h"
 #include "dispatch.h"
-#include "key.h"
-#include "cipher.h"
-#include "kex.h"
 #include "pathnames.h"
-#include "uidswap.h"
-#include "auth-options.h"
-#include "misc.h"
-#include "hostfile.h"
-#include "canohost.h"
-#include "tildexpand.h"
-#include "match.h"
+#include "buffer.h"
+
+#ifdef GSSAPI
+#include "ssh-gss.h"
+#endif
+#include "monitor_wrap.h"
 
 /* import */
 extern ServerOptions options;
 extern u_char *session_id2;
-extern int session_id2_len;
-
-#ifdef WITH_AIXAUTHENTICATE
-extern char *aixloginmsg;
+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
 
-static Authctxt	*x_authctxt = NULL;
-static int one = 1;
-
-typedef struct Authmethod Authmethod;
-struct Authmethod {
-	char	*name;
-	int	(*userauth)(Authctxt *authctxt);
-	int	*enabled;
+Authmethod *authmethods[] = {
+	&method_none,
+	&method_pubkey,
+#ifdef GSSAPI
+	&method_gssapi,
+#endif
+#ifdef JPAKE
+	&method_jpake,
+#endif
+	&method_passwd,
+	&method_kbdint,
+	&method_hostbased,
+	NULL
 };
 
 /* protocol */
 
-static void input_service_request(int, int, void *);
-static void input_userauth_request(int, int, void *);
-static void protocol_error(int, int, void *);
+static void input_service_request(int, u_int32_t, void *);
+static void input_userauth_request(int, u_int32_t, void *);
 
 /* helper */
 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}
-};
 
-/*
- * loop until authctxt->success == TRUE
- */
+char *
+auth2_read_banner(void)
+{
+	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);
+	}
+
+	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
-do_authentication2()
+userauth_send_banner(const char *msg)
 {
-	Authctxt *authctxt = authctxt_new();
+	if (datafellows & SSH_BUG_BANNER)
+		return;
 
-	x_authctxt = authctxt;		/*XXX*/
+	packet_start(SSH2_MSG_USERAUTH_BANNER);
+	packet_put_cstring(msg);
+	packet_put_cstring("");		/* language, unused */
+	packet_send();
+	debug("%s: sent", __func__);
+}
 
-	/* challenge-reponse 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;
+static void
+userauth_banner(void)
+{
+	char *banner = NULL;
 
-	dispatch_init(&protocol_error);
-	dispatch_set(SSH2_MSG_SERVICE_REQUEST, &input_service_request);
-	dispatch_run(DISPATCH_BLOCK, &authctxt->success, authctxt);
-	do_authenticated(authctxt);
+	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);
 }
 
-static void
-protocol_error(int type, int plen, void *ctxt)
+/*
+ * loop until authctxt->success == TRUE
+ */
+void
+do_authentication2(Authctxt *authctxt)
 {
-	log("auth: protocol error: type %d plen %d", type, plen);
-	packet_start(SSH2_MSG_UNIMPLEMENTED);
-	packet_put_int(0);
-	packet_send();
-	packet_write_wait();
+	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, int plen, void *ctxt)
+input_service_request(int type, u_int32_t seq, void *ctxt)
 {
 	Authctxt *authctxt = ctxt;
 	u_int len;
-	int accept = 0;
+	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 (!authctxt->success) {
-			accept = 1;
+			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();
@@ -177,8 +209,9 @@ input_service_request(int type, int plen, void *ctxt)
 	xfree(service);
 }
 
+/*ARGSUSED*/
 static void
-input_userauth_request(int type, int plen, void *ctxt)
+input_userauth_request(int type, u_int32_t seq, void *ctxt)
 {
 	Authctxt *authctxt = ctxt;
 	Authmethod *m = NULL;
@@ -199,25 +232,29 @@ input_userauth_request(int type, int plen, void *ctxt)
 
 	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->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);
-#ifdef USE_PAM
-			start_pam(pw->pw_name);
-#endif
 		} else {
-			log("input_userauth_request: illegal user %s", user);
-#ifdef USE_PAM
-			start_pam("NOUSER");
+			logit("input_userauth_request: invalid user %s", user);
+			authctxt->pw = fakepw();
+#ifdef SSH_AUDIT_EVENTS
+			PRIVSEP(audit_event(SSH_INVALID_USER));
 #endif
 		}
-		setproctitle("%s", pw ? user : "unknown");
-		authctxt->user = xstrdup(user);
+#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: "
@@ -225,18 +262,22 @@ input_userauth_request(int type, int plen, void *ctxt)
 		    authctxt->user, authctxt->service, user, service);
 	}
 	/* reset state */
-	dispatch_set(SSH2_MSG_USERAUTH_INFO_RESPONSE, &protocol_error);
-	authctxt->postponed = 0;
-#ifdef BSD_AUTH
-	if (authctxt->as) {
-		auth_close(authctxt->as);
-		authctxt->as = NULL;
-	}
+	auth2_challenge_stop(authctxt);
+#ifdef JPAKE
+	auth2_jpake_stop(authctxt);
 #endif
 
+#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
+
+	authctxt->postponed = 0;
+
 	/* try to authenticate user */
 	m = authmethod_lookup(method);
-	if (m != NULL) {
+	if (m != NULL && authctxt->failures < options.max_authtries) {
 		debug2("input_userauth_request: try method %s", method);
 		authenticated =	m->userauth(authctxt);
 	}
@@ -258,14 +299,34 @@ userauth_finish(Authctxt *authctxt, int authenticated, char *method)
 
 	/* Special handling for root */
 	if (authenticated && authctxt->pw->pw_uid == 0 &&
-	    !auth_root_allowed(method))
+	    !auth_root_allowed(method)) {
 		authenticated = 0;
+#ifdef SSH_AUDIT_EVENTS
+		PRIVSEP(audit_event(SSH_LOGIN_ROOT_DENIED));
+#endif
+	}
 
 #ifdef USE_PAM
-	if (authenticated && authctxt->user && !do_pam_account(authctxt->user,
-	    NULL))
+	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();
+			}
+			fatal("Access denied for user %s by PAM account "
+			    "configuration", authctxt->user);
+		}
+	}
+#endif
+
+#ifdef _UNICOS
+	if (authenticated && cray_access_denied(authctxt->user)) {
 		authenticated = 0;
-#endif /* USE_PAM */
+		fatal("Access denied for user %s.",authctxt->user);
+	}
+#endif /* _UNICOS */
 
 	/* Log before sending the reply */
 	auth_log(authctxt, authenticated, method, " ssh2");
@@ -276,15 +337,23 @@ userauth_finish(Authctxt *authctxt, int authenticated, char *method)
 	/* XXX todo: check if multiple auth methods are needed */
 	if (authenticated == 1) {
 		/* 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 */
 		authctxt->success = 1;
 	} else {
-		if (authctxt->failures++ > AUTH_FAIL_MAX)
+
+		/* 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);
@@ -295,509 +364,44 @@ userauth_finish(Authctxt *authctxt, int authenticated, char *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;
-}
-
-static int
-userauth_none(Authctxt *authctxt)
-{
-	/* disable method "none", only allowed one time */
-	Authmethod *m = authmethod_lookup("none");
-	if (m != NULL)
-		m->enabled = NULL;
-	packet_done();
-	userauth_banner();
-
-	if (authctxt->valid == 0)
-		return(0);
-
-#ifdef HAVE_CYGWIN
-	if (check_nt_auth(1, authctxt->pw->pw_uid) == 0)
-		return(0);
-#endif
-#ifdef USE_PAM
-	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 */
-}
-
-static int
-userauth_passwd(Authctxt *authctxt)
-{
-	char *password;
-	int authenticated = 0;
-	int change;
-	u_int len;
-	change = packet_get_char();
-	if (change)
-		log("password change not supported");
-	password = packet_get_string(&len);
-	packet_done();
-	if (authctxt->valid &&
-#ifdef HAVE_CYGWIN
-		check_nt_auth(1, authctxt->pw->pw_uid) &&
-#endif
-#ifdef USE_PAM
-	    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;
-}
-
-static int
-userauth_kbdint(Authctxt *authctxt)
-{
-	int authenticated = 0;
-	char *lang, *devs;
-
-	lang = packet_get_string(NULL);
-	devs = packet_get_string(NULL);
-	packet_done();
-
-	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->pw_uid) == 0)
-		return(0);
-#endif
-	return authenticated;
-}
-
-static int
-userauth_pubkey(Authctxt *authctxt)
-{
-	Buffer b;
-	Key *key;
-	char *pkalg, *pkblob, *sig;
-	u_int alen, blen, slen;
-	int have_sig, pktype;
-	int authenticated = 0;
-
-	if (!authctxt->valid) {
-		debug2("userauth_pubkey: disabled because of invalid user");
-		return 0;
-	}
-	have_sig = packet_get_char();
-	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);
-		xfree(pkblob);
-		return 0;
-	}
-	key = key_from_blob(pkblob, blen);
-	if (key != NULL) {
-		if (have_sig) {
-			sig = packet_get_string(&slen);
-			packet_done();
-			buffer_init(&b);
-			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, authctxt->user);
-			buffer_put_cstring(&b,
-			    datafellows & SSH_BUG_PKSERVICE ?
-			    "ssh-userauth" :
-			    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_PK
-			buffer_dump(&b);
-#endif
-			/* test for correct signature */
-			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 {
-			debug("test whether pkalg/pkblob are acceptable");
-			packet_done();
-
-			/* XXX fake reply and always send PK_OK ? */
-			/*
-			 * XXX this allows testing whether a user is allowed
-			 * to login: if you happen to have a valid pubkey this
-			 * message is sent. the message is NEVER sent at all
-			 * if a user is not allowed to login. is this an
-			 * issue? -markus
-			 */
-			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();
-				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->pw_uid) == 0)
-		return(0);
-#endif
-	return authenticated;
-}
-
-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 (x_authctxt != NULL && x_authctxt->valid) ? x_authctxt->pw : NULL;
-}
-
-#define	DELIM	","
-
 static char *
 authmethods_get(void)
 {
-	Authmethod *method = NULL;
-	u_int size = 0;
+	Buffer b;
 	char *list;
+	int i;
 
-	for (method = authmethods; method->name != NULL; method++) {
-		if (strcmp(method->name, "none") == 0)
-			continue;
-		if (method->enabled != NULL && *(method->enabled) != 0) {
-			if (size != 0)
-				size += strlen(DELIM);
-			size += strlen(method->name);
-		}
-	}
-	size++;			/* trailing '\0' */
-	list = xmalloc(size);
-	list[0] = '\0';
-
-	for (method = authmethods; method->name != NULL; method++) {
-		if (strcmp(method->name, "none") == 0)
+	buffer_init(&b);
+	for (i = 0; authmethods[i] != NULL; i++) {
+		if (strcmp(authmethods[i]->name, "none") == 0)
 			continue;
-		if (method->enabled != NULL && *(method->enabled) != 0) {
-			if (list[0] != '\0')
-				strlcat(list, DELIM, size);
-			strlcat(list, method->name, size);
+		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));
 		}
 	}
+	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;
+	int i;
+
 	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");
+		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;
 }
 
-/* return 1 if user allows given key */
-static int
-user_key_allowed2(struct passwd *pw, Key *key, char *file)
-{
-	char line[8192];
-	int found_key = 0;
-	FILE *f;
-	u_long linenum = 0;
-	struct stat st;
-	Key *found;
-
-	if (pw == NULL)
-		return 0;
-
-	/* Temporarily use the user's uid. */
-	temporarily_use_uid(pw);
-
-	debug("trying public key file %s", file);
-
-	/* 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 &&
-	    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->type);
-
-	while (fgets(line, sizeof(line), f)) {
-		char *cp, *options = NULL;
-		linenum++;
-		/* Skip leading whitespace, empty and comment lines. */
-		for (cp = line; *cp == ' ' || *cp == '\t'; cp++)
-			;
-		if (!*cp || *cp == '\n' || *cp == '#')
-			continue;
-
-		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] == '"')
-					cp++;	/* Skip both */
-				else if (*cp == '"')
-					quoted = !quoted;
-			}
-			/* Skip remaining whitespace. */
-			for (; *cp == ' ' || *cp == '\t'; cp++)
-				;
-			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, file, linenum) == 1) {
-			found_key = 1;
-			debug("matching key found: file %s, line %lu",
-			    file, linenum);
-			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;
-	int host_status, 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);
-}
-