X-Git-Url: http://andersk.mit.edu/gitweb/openssh.git/blobdiff_plain/0b242b12f247fc000b6667df700d8a4523fc60fe..a8a21a53bf8e9f5701c04c6229264a1329730220:/auth1.c

diff --git a/auth1.c b/auth1.c
index dedf898e..2ea638b9 100644
--- a/auth1.c
+++ b/auth1.c
@@ -1,31 +1,38 @@
 /*
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
  *                    All rights reserved
+ *
+ * As far as I am concerned, the code I have written for this software
+ * can be used freely for any purpose.  Any derived versions of this
+ * software must be clearly marked as such, and if the derived work is
+ * incompatible with the protocol description in the RFC file, it must be
+ * called by a name other than "ssh" or "Secure Shell".
  */
 
 #include "includes.h"
-RCSID("$OpenBSD: auth1.c,v 1.2 2000/04/29 18:11:52 markus Exp $");
+RCSID("$OpenBSD: auth1.c,v 1.31 2001/12/27 20:39:58 markus Exp $");
 
 #include "xmalloc.h"
 #include "rsa.h"
-#include "ssh.h"
+#include "ssh1.h"
 #include "packet.h"
 #include "buffer.h"
-#include "cipher.h"
 #include "mpaux.h"
+#include "log.h"
 #include "servconf.h"
 #include "compat.h"
 #include "auth.h"
 #include "session.h"
+#include "misc.h"
+#include "uidswap.h"
 
 /* import */
 extern ServerOptions options;
-extern char *forced_command;
 
 /*
  * convert ssh auth msg type into description
  */
-char *
+static char *
 get_authname(int type)
 {
 	static char buf[1024];
@@ -38,13 +45,12 @@ get_authname(int type)
 		return "rhosts-rsa";
 	case SSH_CMSG_AUTH_RHOSTS:
 		return "rhosts";
-#ifdef KRB4
+	case SSH_CMSG_AUTH_TIS:
+	case SSH_CMSG_AUTH_TIS_RESPONSE:
+		return "challenge-response";
+#if defined(KRB4) || defined(KRB5)
 	case SSH_CMSG_AUTH_KERBEROS:
 		return "kerberos";
-#endif
-#ifdef SKEY
-	case SSH_CMSG_AUTH_TIS_RESPONSE:
-		return "s/key";
 #endif
 	}
 	snprintf(buf, sizeof buf, "bad-auth-msg-%d", type);
@@ -52,169 +58,115 @@ get_authname(int type)
 }
 
 /*
- * The user does not exist or access is denied,
- * but fake indication that authentication is needed.
+ * read packets, try to authenticate the user and
+ * return only if authentication is successful
  */
-void
-do_fake_authloop1(char *user)
+static void
+do_authloop(Authctxt *authctxt)
 {
-	int attempt = 0;
-
-	log("Faking authloop for illegal user %.200s from %.200s port %d",
-	    user,
-	    get_remote_ipaddr(),
-	    get_remote_port());
-
-#ifdef WITH_AIXAUTHENTICATE 
-		if (strncmp(get_authname(type),"password",
-		    strlen(get_authname(type))) == 0)
-			loginfailed(pw->pw_name,get_canonical_hostname(),"ssh");
-#endif /* WITH_AIXAUTHENTICATE */
+	int authenticated = 0;
+	u_int bits;
+	Key *client_host_key;
+	BIGNUM *n;
+	char *client_user, *password;
+	char info[1024];
+	u_int dlen;
+	int plen, nlen, elen;
+	u_int ulen;
+	int type = 0;
+	struct passwd *pw = authctxt->pw;
 
-	/* Indicate that authentication is needed. */
-	packet_start(SSH_SMSG_FAILURE);
-	packet_send();
-	packet_write_wait();
+	debug("Attempting authentication for %s%.100s.",
+	    authctxt->valid ? "" : "illegal user ", authctxt->user);
 
-	/*
-	 * Keep reading packets, and always respond with a failure.  This is
-	 * to avoid disclosing whether such a user really exists.
-	 */
-	for (attempt = 1;; attempt++) {
-		/* Read a packet.  This will not return if the client disconnects. */
-		int plen;
-#ifndef SKEY
-		(void)packet_read(&plen);
-#else /* SKEY */
-		int type = packet_read(&plen);
-		unsigned int dlen;
-		char *password, *skeyinfo;
-		password = NULL;
-		/* Try to send a fake s/key challenge. */
-		if (options.skey_authentication == 1 &&
-		    (skeyinfo = skey_fake_keyinfo(user)) != NULL) {
-			if (type == SSH_CMSG_AUTH_TIS) {
-				packet_start(SSH_SMSG_AUTH_TIS_CHALLENGE);
-				packet_put_string(skeyinfo, strlen(skeyinfo));
-				packet_send();
-				packet_write_wait();
-				continue;
-			} else if (type == SSH_CMSG_AUTH_PASSWORD &&
-				   options.password_authentication &&
-				   (password = packet_get_string(&dlen)) != NULL &&
-				   dlen == 5 &&
-				   strncasecmp(password, "s/key", 5) == 0 ) {
-				packet_send_debug(skeyinfo);
-			}
-		}
-		if (password != NULL)
-			xfree(password);
+	/* If the user has no password, accept authentication immediately. */
+	if (options.password_authentication &&
+#if defined(KRB4) || defined(KRB5)
+	    (!options.kerberos_authentication || options.kerberos_or_local_passwd) &&
 #endif
-		if (attempt > AUTH_FAIL_MAX)
-			packet_disconnect(AUTH_FAIL_MSG, user);
-
-		/*
-		 * Send failure.  This should be indistinguishable from a
-		 * failed authentication.
-		 */
-		packet_start(SSH_SMSG_FAILURE);
-		packet_send();
-		packet_write_wait();
+#ifdef USE_PAM
+	    auth_pam_password(pw, "")) {
+#elif defined(HAVE_OSF_SIA)
+	    0) {
+#else
+	    auth_password(authctxt, "")) {
+#endif
+		auth_log(authctxt, 1, "without authentication", "");
+		return;
 	}
-	/* NOTREACHED */
-	abort();
-}
-
-/*
- * read packets and try to authenticate local user *pw.
- * return if authentication is successfull
- */
-void
-do_authloop(struct passwd * pw)
-{
-	int attempt = 0;
-	unsigned int bits;
-	RSA *client_host_key;
-	BIGNUM *n;
-	char *client_user = NULL, *password = NULL;
-	char user[1024];
-	unsigned int dlen;
-	int plen, nlen, elen;
-	unsigned int ulen;
-	int type = 0;
-	void (*authlog) (const char *fmt,...) = verbose;
 
 	/* Indicate that authentication is needed. */
 	packet_start(SSH_SMSG_FAILURE);
 	packet_send();
 	packet_write_wait();
 
-	for (attempt = 1;; attempt++) {
-		int authenticated = 0;
-		strlcpy(user, "", sizeof user);
+	client_user = NULL;
+
+	for (;;) {
+		/* default to fail */
+		authenticated = 0;
+
+		info[0] = '\0';
 
 		/* Get a packet from the client. */
 		type = packet_read(&plen);
 
 		/* Process the packet. */
 		switch (type) {
-#ifdef AFS
-		case SSH_CMSG_HAVE_KERBEROS_TGT:
-			if (!options.kerberos_tgt_passing) {
-				/* packet_get_all(); */
-				verbose("Kerberos tgt passing disabled.");
-				break;
-			} else {
-				/* Accept Kerberos tgt. */
-				char *tgt = packet_get_string(&dlen);
-				packet_integrity_check(plen, 4 + dlen, type);
-				if (!auth_kerberos_tgt(pw, tgt))
-					verbose("Kerberos tgt REFUSED for %s", pw->pw_name);
-				xfree(tgt);
-			}
-			continue;
 
-		case SSH_CMSG_HAVE_AFS_TOKEN:
-			if (!options.afs_token_passing || !k_hasafs()) {
-				/* packet_get_all(); */
-				verbose("AFS token passing disabled.");
-				break;
-			} else {
-				/* Accept AFS token. */
-				char *token_string = packet_get_string(&dlen);
-				packet_integrity_check(plen, 4 + dlen, type);
-				if (!auth_afs_token(pw, token_string))
-					verbose("AFS token REFUSED for %s", pw->pw_name);
-				xfree(token_string);
-			}
-			continue;
-#endif /* AFS */
-#ifdef KRB4
+#if defined(KRB4) || defined(KRB5)
 		case SSH_CMSG_AUTH_KERBEROS:
 			if (!options.kerberos_authentication) {
-				/* packet_get_all(); */
 				verbose("Kerberos authentication disabled.");
-				break;
 			} else {
-				/* Try Kerberos v4 authentication. */
-				KTEXT_ST auth;
-				char *tkt_user = NULL;
-				char *kdata = packet_get_string((unsigned int *) &auth.length);
-				packet_integrity_check(plen, 4 + auth.length, type);
-
-				if (auth.length < MAX_KTXT_LEN)
-					memcpy(auth.dat, kdata, auth.length);
-				xfree(kdata);
-
-				authenticated = auth_krb4(pw->pw_name, &auth, &tkt_user);
+				char *kdata = packet_get_string(&dlen);
+				packet_done();
 
-				if (authenticated) {
-					snprintf(user, sizeof user, " tktuser %s", tkt_user);
-					xfree(tkt_user);
+				if (kdata[0] == 4) { /* KRB_PROT_VERSION */
+#ifdef KRB4
+					KTEXT_ST tkt;
+
+					tkt.length = dlen;
+					if (tkt.length < MAX_KTXT_LEN)
+						memcpy(tkt.dat, kdata, tkt.length);
+
+					if (auth_krb4(authctxt, &tkt, &client_user)) {
+						authenticated = 1;
+						snprintf(info, sizeof(info),
+						    " tktuser %.100s",
+						    client_user);
+					}
+#endif /* KRB4 */
+				} else {
+#ifdef KRB5
+					krb5_data tkt;
+					tkt.length = dlen;
+					tkt.data = kdata;
+
+					if (auth_krb5(authctxt, &tkt, &client_user)) {
+						authenticated = 1;
+						snprintf(info, sizeof(info),
+						    " tktuser %.100s",
+						    client_user);
+					}
+#endif /* KRB5 */
 				}
+				xfree(kdata);
 			}
 			break;
-#endif /* KRB4 */
+#endif /* KRB4 || KRB5 */
+
+#if defined(AFS) || defined(KRB5)
+			/* XXX - punt on backward compatibility here. */
+		case SSH_CMSG_HAVE_KERBEROS_TGT:
+			packet_send_debug("Kerberos TGT passing disabled before authentication.");
+			break;
+#ifdef AFS
+		case SSH_CMSG_HAVE_AFS_TOKEN:
+			packet_send_debug("AFS token passing disabled before authentication.");
+			break;
+#endif /* AFS */
+#endif /* AFS || KRB5 */
 
 		case SSH_CMSG_AUTH_RHOSTS:
 			if (!options.rhosts_authentication) {
@@ -228,13 +180,12 @@ do_authloop(struct passwd * pw)
 			 * IP-spoofing on a local network.)
 			 */
 			client_user = packet_get_string(&ulen);
-			packet_integrity_check(plen, 4 + ulen, type);
+			packet_done();
 
-			/* Try to authenticate using /etc/hosts.equiv and
-			   .rhosts. */
+			/* Try to authenticate using /etc/hosts.equiv and .rhosts. */
 			authenticated = auth_rhosts(pw, client_user);
 
-			snprintf(user, sizeof user, " ruser %s", client_user);
+			snprintf(info, sizeof info, " ruser %.100s", client_user);
 			break;
 
 		case SSH_CMSG_AUTH_RHOSTS_RSA:
@@ -250,26 +201,22 @@ do_authloop(struct passwd * pw)
 			client_user = packet_get_string(&ulen);
 
 			/* Get the client host key. */
-			client_host_key = RSA_new();
-			if (client_host_key == NULL)
-				fatal("RSA_new failed");
-			client_host_key->e = BN_new();
-			client_host_key->n = BN_new();
-			if (client_host_key->e == NULL || client_host_key->n == NULL)
-				fatal("BN_new failed");
+			client_host_key = key_new(KEY_RSA1);
 			bits = packet_get_int();
-			packet_get_bignum(client_host_key->e, &elen);
-			packet_get_bignum(client_host_key->n, &nlen);
+			packet_get_bignum(client_host_key->rsa->e, &elen);
+			packet_get_bignum(client_host_key->rsa->n, &nlen);
 
-			if (bits != BN_num_bits(client_host_key->n))
-				log("Warning: keysize mismatch for client_host_key: "
-				    "actual %d, announced %d", BN_num_bits(client_host_key->n), bits);
-			packet_integrity_check(plen, (4 + ulen) + 4 + elen + nlen, type);
+			if (bits != BN_num_bits(client_host_key->rsa->n))
+				verbose("Warning: keysize mismatch for client_host_key: "
+				    "actual %d, announced %d",
+				     BN_num_bits(client_host_key->rsa->n), bits);
+			packet_done();
 
-			authenticated = auth_rhosts_rsa(pw, client_user, client_host_key);
-			RSA_free(client_host_key);
+			authenticated = auth_rhosts_rsa(pw, client_user,
+			    client_host_key);
+			key_free(client_host_key);
 
-			snprintf(user, sizeof user, " ruser %s", client_user);
+			snprintf(info, sizeof info, " ruser %.100s", client_user);
 			break;
 
 		case SSH_CMSG_AUTH_RSA:
@@ -278,9 +225,10 @@ do_authloop(struct passwd * pw)
 				break;
 			}
 			/* RSA authentication requested. */
-			n = BN_new();
+			if ((n = BN_new()) == NULL)
+				fatal("do_authloop: BN_new failed");
 			packet_get_bignum(n, &nlen);
-			packet_integrity_check(plen, nlen, type);
+			packet_done();
 			authenticated = auth_rsa(pw, n);
 			BN_clear_free(n);
 			break;
@@ -296,34 +244,33 @@ do_authloop(struct passwd * pw)
 			 * not visible to an outside observer.
 			 */
 			password = packet_get_string(&dlen);
-			packet_integrity_check(plen, 4 + dlen, type);
+			packet_done();
 
 #ifdef USE_PAM
 			/* Do PAM auth with password */
 			authenticated = auth_pam_password(pw, password);
-#else /* USE_PAM */
+#elif defined(HAVE_OSF_SIA)
+			/* Do SIA auth with password */
+			authenticated = auth_sia_password(authctxt->user, 
+			    password);
+#else /* !USE_PAM && !HAVE_OSF_SIA */
 			/* Try authentication with the password. */
-			authenticated = auth_password(pw, password);
+			authenticated = auth_password(authctxt, password);
 #endif /* USE_PAM */
 
 			memset(password, 0, strlen(password));
 			xfree(password);
 			break;
 
-#ifdef SKEY
 		case SSH_CMSG_AUTH_TIS:
 			debug("rcvd SSH_CMSG_AUTH_TIS");
-			if (options.skey_authentication == 1) {
-				char *skeyinfo = skey_keyinfo(pw->pw_name);
-				if (skeyinfo == NULL) {
-					debug("generating fake skeyinfo for %.100s.", pw->pw_name);
-					skeyinfo = skey_fake_keyinfo(pw->pw_name);
-				}
-				if (skeyinfo != NULL) {
-					/* we send our s/key- in tis-challenge messages */
-					debug("sending challenge '%s'", skeyinfo);
+			if (options.challenge_response_authentication == 1) {
+				char *challenge = get_challenge(authctxt);
+				if (challenge != NULL) {
+					debug("sending challenge '%s'", challenge);
 					packet_start(SSH_SMSG_AUTH_TIS_CHALLENGE);
-					packet_put_string(skeyinfo, strlen(skeyinfo));
+					packet_put_cstring(challenge);
+					xfree(challenge);
 					packet_send();
 					packet_write_wait();
 					continue;
@@ -332,21 +279,15 @@ do_authloop(struct passwd * pw)
 			break;
 		case SSH_CMSG_AUTH_TIS_RESPONSE:
 			debug("rcvd SSH_CMSG_AUTH_TIS_RESPONSE");
-			if (options.skey_authentication == 1) {
+			if (options.challenge_response_authentication == 1) {
 				char *response = packet_get_string(&dlen);
-				debug("skey response == '%s'", response);
-				packet_integrity_check(plen, 4 + dlen, type);
-				authenticated = (skey_haskey(pw->pw_name) == 0 &&
-						 skey_passcheck(pw->pw_name, response) != -1);
+				debug("got response '%s'", response);
+				packet_done();
+				authenticated = verify_response(authctxt, response);
+				memset(response, 'r', dlen);
 				xfree(response);
 			}
 			break;
-#else
-		case SSH_CMSG_AUTH_TIS:
-			/* TIS Authentication is unsupported */
-			log("TIS authentication unsupported.");
-			break;
-#endif
 
 		default:
 			/*
@@ -356,62 +297,54 @@ do_authloop(struct passwd * pw)
 			log("Unknown message during authentication: type %d", type);
 			break;
 		}
-
-		/*
-		 * Check if the user is logging in as root and root logins
-		 * are disallowed.
-		 * Note that root login is allowed for forced commands.
-		 */
-		if (authenticated && pw->pw_uid == 0 && !options.permit_root_login) {
-			if (forced_command) {
-				log("Root login accepted for forced command.");
-			} else {
-				authenticated = 0;
-				log("ROOT LOGIN REFUSED FROM %.200s",
-				    get_canonical_hostname());
-			}
-		}
-
-		/* Raise logging level */
-		if (authenticated ||
-		    attempt == AUTH_FAIL_LOG ||
-		    type == SSH_CMSG_AUTH_PASSWORD)
-			authlog = log;
-
-		authlog("%s %s for %.200s from %.200s port %d%s",
-			authenticated ? "Accepted" : "Failed",
-			get_authname(type),
-			pw->pw_uid == 0 ? "ROOT" : pw->pw_name,
-			get_remote_ipaddr(),
-			get_remote_port(),
-			user);
-
-#ifdef USE_PAM
-		if (authenticated) {
-			if (!do_pam_account(pw->pw_name, client_user)) {
-				if (client_user != NULL) {
-					xfree(client_user);
-					client_user = NULL;
-				}
-				do_fake_authloop1(pw->pw_name);
-			}
-			return;
+#ifdef BSD_AUTH
+		if (authctxt->as) {
+			auth_close(authctxt->as);
+			authctxt->as = NULL;
 		}
-#else /* USE_PAM */
-		if (authenticated) {
-			return;
+#endif
+		if (!authctxt->valid && authenticated)
+			fatal("INTERNAL ERROR: authenticated invalid user %s",
+			    authctxt->user);
+
+#ifdef HAVE_CYGWIN
+		if (authenticated &&
+		    !check_nt_auth(type == SSH_CMSG_AUTH_PASSWORD, pw)) {
+			packet_disconnect("Authentication rejected for uid %d.",
+			pw == NULL ? -1 : pw->pw_uid);
+			authenticated = 0;
 		}
-#endif /* USE_PAM */
+#else
+		/* Special handling for root */
+		if (authenticated && authctxt->pw->pw_uid == 0 &&
+		    !auth_root_allowed(get_authname(type)))
+			authenticated = 0;
+#endif
+#ifdef USE_PAM
+		if (authenticated && !do_pam_account(pw->pw_name, client_user))
+			authenticated = 0;
+#endif
+
+		/* Log before sending the reply */
+		auth_log(authctxt, authenticated, get_authname(type), info);
 
 		if (client_user != NULL) {
 			xfree(client_user);
 			client_user = NULL;
 		}
 
-		if (attempt > AUTH_FAIL_MAX)
-			packet_disconnect(AUTH_FAIL_MSG, pw->pw_name);
+		if (authenticated)
+			return;
+
+		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);
+		}
 
-		/* Send a message indicating that the authentication attempt failed. */
 		packet_start(SSH_SMSG_FAILURE);
 		packet_send();
 		packet_write_wait();
@@ -423,90 +356,70 @@ do_authloop(struct passwd * pw)
  * been exchanged and encryption is enabled.
  */
 void
-do_authentication()
+do_authentication(void)
 {
-	struct passwd *pw, pwcopy;
+	Authctxt *authctxt;
+	struct passwd *pw;
 	int plen;
-	unsigned int ulen;
-	char *user;
-#ifdef WITH_AIXAUTHENTICATE
-	char *loginmsg;
-#endif /* WITH_AIXAUTHENTICATE */
+	u_int ulen;
+	char *p, *user, *style = NULL;
 
 	/* Get the name of the user that we wish to log in as. */
 	packet_read_expect(&plen, SSH_CMSG_USER);
 
 	/* Get the user name. */
 	user = packet_get_string(&ulen);
-	packet_integrity_check(plen, (4 + ulen), SSH_CMSG_USER);
+	packet_done();
 
-	setproctitle("%s", user);
+	if ((style = strchr(user, ':')) != NULL)
+		*style++ = '\0';
 
-#ifdef AFS
-	/* If machine has AFS, set process authentication group. */
-	if (k_hasafs()) {
-		k_setpag();
-		k_unlog();
-	}
-#endif /* AFS */
+	/* XXX - SSH.com Kerberos v5 braindeath. */
+	if ((p = strchr(user, '@')) != NULL)
+		*p = '\0';
+
+	authctxt = authctxt_new();
+	authctxt->user = user;
+	authctxt->style = style;
 
 	/* Verify that the user is a valid user. */
 	pw = getpwnam(user);
-	if (!pw || !allowed_user(pw))
-		do_fake_authloop1(user);
-	xfree(user);
-
-	/* Take a copy of the returned structure. */
-	memset(&pwcopy, 0, sizeof(pwcopy));
-	pwcopy.pw_name = xstrdup(pw->pw_name);
-	pwcopy.pw_passwd = xstrdup(pw->pw_passwd);
-	pwcopy.pw_uid = pw->pw_uid;
-	pwcopy.pw_gid = pw->pw_gid;
-	pwcopy.pw_dir = xstrdup(pw->pw_dir);
-	pwcopy.pw_shell = xstrdup(pw->pw_shell);
-	pw = &pwcopy;
+	if (pw && allowed_user(pw)) {
+		authctxt->valid = 1;
+		pw = pwcopy(pw);
+	} else {
+		debug("do_authentication: illegal user %s", user);
+		pw = NULL;
+	}
+	authctxt->pw = pw;
+
+	setproctitle("%s", pw ? user : "unknown");
 
 #ifdef USE_PAM
-	start_pam(pw);
+	if (pw)
+		start_pam(user);
 #endif
 
 	/*
 	 * If we are not running as root, the user must have the same uid as
-	 * the server.
+	 * the server. (Unless you are running Windows)
 	 */
-	if (getuid() != 0 && pw->pw_uid != getuid())
+#ifndef HAVE_CYGWIN
+	if (getuid() != 0 && pw && pw->pw_uid != getuid())
 		packet_disconnect("Cannot change user when server not running as root.");
+#endif
 
-	debug("Attempting authentication for %.100s.", pw->pw_name);
-
-	/* If the user has no password, accept authentication immediately. */
-	if (options.password_authentication &&
-#ifdef KRB4
-	    (!options.kerberos_authentication || options.kerberos_or_local_passwd) &&
-#endif /* KRB4 */
-#ifdef USE_PAM
-	    auth_pam_password(pw, "")) {
-#else /* USE_PAM */
-	    auth_password(pw, "")) {
-#endif /* USE_PAM */
-		/* Authentication with empty password succeeded. */
-		log("Login for user %s from %.100s, accepted without authentication.",
-		    pw->pw_name, get_remote_ipaddr());
-	} else {
-		/* Loop until the user has been authenticated or the
-		   connection is closed, do_authloop() returns only if
-		   authentication is successfull */
-		do_authloop(pw);
-	}
+	/*
+	 * Loop until the user has been authenticated or the connection is
+	 * closed, do_authloop() returns only if authentication is successful
+	 */
+	do_authloop(authctxt);
 
 	/* The user has been authenticated and accepted. */
-#ifdef WITH_AIXAUTHENTICATE
-	loginsuccess(user,get_canonical_hostname(),"ssh",&loginmsg);
-#endif /* WITH_AIXAUTHENTICATE */
 	packet_start(SSH_SMSG_SUCCESS);
 	packet_send();
 	packet_write_wait();
 
 	/* Perform session preparation. */
-	do_authenticated(pw);
+	do_authenticated(authctxt);
 }