===================================================================
RCS file: /cvsrepo/anoncvs/cvs/src/usr.bin/ssh/sshconnect2.c,v
retrieving revision 1.116
retrieving revision 1.117
diff -u -r1.116 -r1.117
--- src/usr.bin/ssh/sshconnect2.c	2003/04/08 20:21:29	1.116
+++ src/usr.bin/ssh/sshconnect2.c	2003/05/12 16:55:37	1.117
@@ -23,7 +23,7 @@
  */
 
 #include "includes.h"
-RCSID("$OpenBSD: sshconnect2.c,v 1.116 2003/04/08 20:21:29 itojun Exp $");
+RCSID("$OpenBSD: sshconnect2.c,v 1.117 2003/05/12 16:55:37 markus Exp $");
 
 #include "ssh.h"
 #include "ssh2.h"
@@ -141,10 +141,18 @@
 
 typedef struct Authctxt Authctxt;
 typedef struct Authmethod Authmethod;
+typedef struct identity Identity;
+typedef struct idlist Idlist;
 
-typedef int sign_cb_fn(
-    Authctxt *authctxt, Key *key,
-    u_char **sigp, u_int *lenp, u_char *data, u_int datalen);
+struct identity {
+	TAILQ_ENTRY(identity) next;
+	AuthenticationConnection *ac;	/* set if agent supports key */
+	Key	*key;			/* public/private key */
+	char	*filename;		/* comment for agent-only keys */
+	int	tried;
+	int	isprivate;		/* key points to the private key */
+};
+TAILQ_HEAD(idlist, identity);
 
 struct Authctxt {
 	const char *server_user;
@@ -155,9 +163,7 @@
 	int success;
 	char *authlist;
 	/* pubkey */
-	Key *last_key;
-	sign_cb_fn *last_key_sign;
-	int last_key_hint;
+	Idlist keys;
 	AuthenticationConnection *agent;
 	/* hostbased */
 	Sensitive *sensitive;
@@ -187,8 +193,11 @@
 
 void	userauth(Authctxt *, char *);
 
-static int sign_and_send_pubkey(Authctxt *, Key *, sign_cb_fn *);
+static int sign_and_send_pubkey(Authctxt *, Identity *);
 static void clear_auth_state(Authctxt *);
+static void pubkey_prepare(Authctxt *);
+static void pubkey_cleanup(Authctxt *);
+static Key *load_identity_file(char *);
 
 static Authmethod *authmethod_get(char *authlist);
 static Authmethod *authmethod_lookup(const char *name);
@@ -251,7 +260,7 @@
 
 	/* setup authentication context */
 	memset(&authctxt, 0, sizeof(authctxt));
-	authctxt.agent = ssh_get_authentication_connection();
+	pubkey_prepare(&authctxt);
 	authctxt.server_user = server_user;
 	authctxt.local_user = local_user;
 	authctxt.host = host;
@@ -273,9 +282,7 @@
 	dispatch_set(SSH2_MSG_USERAUTH_BANNER, &input_userauth_banner);
 	dispatch_run(DISPATCH_BLOCK, &authctxt.success, &authctxt);	/* loop until success */
 
-	if (authctxt.agent != NULL)
-		ssh_close_authentication_connection(authctxt.agent);
-
+	pubkey_cleanup(&authctxt);
 	debug("Authentication succeeded (%s).", authctxt.method->name);
 }
 void
@@ -360,6 +367,7 @@
 {
 	Authctxt *authctxt = ctxt;
 	Key *key = NULL;
+	Identity *id = NULL;
 	Buffer b;
 	int pktype, sent = 0;
 	u_int alen, blen;
@@ -382,40 +390,33 @@
 	}
 	packet_check_eom();
 
-	debug("Server accepts key: pkalg %s blen %u lastkey %p hint %d",
-	    pkalg, blen, authctxt->last_key, authctxt->last_key_hint);
+	debug("Server accepts key: pkalg %s blen %u", pkalg, blen);
 
-	do {
-		if (authctxt->last_key == NULL ||
-		    authctxt->last_key_sign == NULL) {
-			debug("no last key or no sign cb");
+	if ((pktype = key_type_from_name(pkalg)) == KEY_UNSPEC) {
+		debug("unknown pkalg %s", pkalg);
+		goto done;
+	}
+	if ((key = key_from_blob(pkblob, blen)) == NULL) {
+		debug("no key from blob. pkalg %s", pkalg);
+		goto done;
+	}
+	if (key->type != pktype) {
+		error("input_userauth_pk_ok: type mismatch "
+		    "for decoded key (received %d, expected %d)",
+		    key->type, pktype);
+		goto done;
+	}
+	fp = key_fingerprint(key, SSH_FP_MD5, SSH_FP_HEX);
+	debug2("input_userauth_pk_ok: fp %s", fp);
+	xfree(fp);
+
+	TAILQ_FOREACH(id, &authctxt->keys, next) {
+		if (key_equal(key, id->key)) {
+			sent = sign_and_send_pubkey(authctxt, id);
 			break;
 		}
-		if ((pktype = key_type_from_name(pkalg)) == KEY_UNSPEC) {
-			debug("unknown pkalg %s", pkalg);
-			break;
-		}
-		if ((key = key_from_blob(pkblob, blen)) == NULL) {
-			debug("no key from blob. pkalg %s", pkalg);
-			break;
-		}
-		if (key->type != pktype) {
-			error("input_userauth_pk_ok: type mismatch "
-			    "for decoded key (received %d, expected %d)",
-			    key->type, pktype);
-			break;
-		}
-		fp = key_fingerprint(key, SSH_FP_MD5, SSH_FP_HEX);
-		debug2("input_userauth_pk_ok: fp %s", fp);
-		xfree(fp);
-		if (!key_equal(key, authctxt->last_key)) {
-			debug("key != last_key");
-			break;
-		}
-		sent = sign_and_send_pubkey(authctxt, key,
-		   authctxt->last_key_sign);
-	} while (0);
-
+	}
+done:
 	if (key != NULL)
 		key_free(key);
 	xfree(pkalg);
@@ -428,7 +429,6 @@
 	/* try another method if we did not send a packet */
 	if (sent == 0)
 		userauth(authctxt, NULL);
-
 }
 
 int
@@ -547,18 +547,35 @@
 {
 	/* XXX clear authentication state */
 	dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, NULL);
+}
 
-	if (authctxt->last_key != NULL && authctxt->last_key_hint == -1) {
-		debug3("clear_auth_state: key_free %p", authctxt->last_key);
-		key_free(authctxt->last_key);
-	}
-	authctxt->last_key = NULL;
-	authctxt->last_key_hint = -2;
-	authctxt->last_key_sign = NULL;
+static int
+identity_sign(Identity *id, u_char **sigp, u_int *lenp,
+    u_char *data, u_int datalen)
+{
+	Key *prv;
+	int ret;
+
+	/* the agent supports this key */
+	if (id->ac)
+		return (ssh_agent_sign(id->ac, id->key, sigp, lenp,
+		    data, datalen));
+	/*
+	 * we have already loaded the private key or
+	 * the private key is stored in external hardware
+	 */
+	if (id->isprivate || (id->key->flags & KEY_FLAG_EXT))
+		return (key_sign(id->key, sigp, lenp, data, datalen));
+	/* load the private key from the file */
+	if ((prv = load_identity_file(id->filename)) == NULL)
+		return (-1);
+	ret = key_sign(prv, sigp, lenp, data, datalen);
+	key_free(prv);
+	return (ret);
 }
 
 static int
-sign_and_send_pubkey(Authctxt *authctxt, Key *k, sign_cb_fn *sign_callback)
+sign_and_send_pubkey(Authctxt *authctxt, Identity *id)
 {
 	Buffer b;
 	u_char *blob, *signature;
@@ -569,7 +586,7 @@
 
 	debug3("sign_and_send_pubkey");
 
-	if (key_to_blob(k, &blob, &bloblen) == 0) {
+	if (key_to_blob(id->key, &blob, &bloblen) == 0) {
 		/* we cannot handle this key */
 		debug3("sign_and_send_pubkey: cannot handle key");
 		return 0;
@@ -594,12 +611,12 @@
 	} else {
 		buffer_put_cstring(&b, authctxt->method->name);
 		buffer_put_char(&b, have_sig);
-		buffer_put_cstring(&b, key_ssh_name(k));
+		buffer_put_cstring(&b, key_ssh_name(id->key));
 	}
 	buffer_put_string(&b, blob, bloblen);
 
 	/* generate signature */
-	ret = (*sign_callback)(authctxt, k, &signature, &slen,
+	ret = identity_sign(id, &signature, &slen,
 	    buffer_ptr(&b), buffer_len(&b));
 	if (ret == -1) {
 		xfree(blob);
@@ -619,7 +636,7 @@
 		buffer_put_cstring(&b, authctxt->method->name);
 		buffer_put_char(&b, have_sig);
 		if (!(datafellows & SSH_BUG_PKAUTH))
-			buffer_put_cstring(&b, key_ssh_name(k));
+			buffer_put_cstring(&b, key_ssh_name(id->key));
 		buffer_put_string(&b, blob, bloblen);
 	}
 	xfree(blob);
@@ -643,23 +660,19 @@
 }
 
 static int
-send_pubkey_test(Authctxt *authctxt, Key *k, sign_cb_fn *sign_callback,
-    int hint)
+send_pubkey_test(Authctxt *authctxt, Identity *id)
 {
 	u_char *blob;
 	u_int bloblen, have_sig = 0;
 
 	debug3("send_pubkey_test");
 
-	if (key_to_blob(k, &blob, &bloblen) == 0) {
+	if (key_to_blob(id->key, &blob, &bloblen) == 0) {
 		/* we cannot handle this key */
 		debug3("send_pubkey_test: cannot handle key");
 		return 0;
 	}
 	/* register callback for USERAUTH_PK_OK message */
-	authctxt->last_key_sign = sign_callback;
-	authctxt->last_key_hint = hint;
-	authctxt->last_key = k;
 	dispatch_set(SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok);
 
 	packet_start(SSH2_MSG_USERAUTH_REQUEST);
@@ -668,7 +681,7 @@
 	packet_put_cstring(authctxt->method->name);
 	packet_put_char(have_sig);
 	if (!(datafellows & SSH_BUG_PKAUTH))
-		packet_put_cstring(key_ssh_name(k));
+		packet_put_cstring(key_ssh_name(id->key));
 	packet_put_string(blob, bloblen);
 	xfree(blob);
 	packet_send();
@@ -713,103 +726,134 @@
 	return private;
 }
 
-static int
-identity_sign_cb(Authctxt *authctxt, Key *key, u_char **sigp, u_int *lenp,
-    u_char *data, u_int datalen)
+/*
+ * try keys in the following order:
+ *	1. agent keys that are found in the config file
+ *	2. other agent keys
+ *	3. keys that are only listed in the config file
+ */
+static void
+pubkey_prepare(Authctxt *authctxt)
 {
-	Key *private;
-	int idx, ret;
+	Identity *id;
+	Idlist agent, files, *preferred;
+	Key *key;
+	AuthenticationConnection *ac;
+	char *comment;
+	int i, found;
 
-	idx = authctxt->last_key_hint;
-	if (idx < 0)
-		return -1;
+	TAILQ_INIT(&agent);	/* keys from the agent */
+	TAILQ_INIT(&files);	/* keys from the config file */
+	preferred = &authctxt->keys;
+	TAILQ_INIT(preferred);	/* preferred order of keys */
 
-	/* private key is stored in external hardware */
-	if (options.identity_keys[idx]->flags & KEY_FLAG_EXT)
-		return key_sign(options.identity_keys[idx], sigp, lenp, data, datalen);
-
-	private = load_identity_file(options.identity_files[idx]);
-	if (private == NULL)
-		return -1;
-	ret = key_sign(private, sigp, lenp, data, datalen);
-	key_free(private);
-	return ret;
+	/* list of keys stored in the filesystem */
+	for (i = 0; i < options.num_identity_files; i++) {
+		key = options.identity_keys[i];
+		if (key && key->type == KEY_RSA1)
+			continue;
+		options.identity_keys[i] = NULL;
+		id = xmalloc(sizeof(*id));
+		memset(id, 0, sizeof(*id));
+		id->key = key;
+		id->filename = xstrdup(options.identity_files[i]);
+		TAILQ_INSERT_TAIL(&files, id, next);
+	}
+	/* list of keys supported by the agent */
+	if ((ac = ssh_get_authentication_connection())) {
+		for (key = ssh_get_first_identity(ac, &comment, 2);
+		    key != NULL;
+		    key = ssh_get_next_identity(ac, &comment, 2)) {
+			found = 0;
+			TAILQ_FOREACH(id, &files, next) {
+				/* agent keys from the config file are preferred */ 
+				if (key_equal(key, id->key)) {
+					key_free(key);
+					xfree(comment);
+					TAILQ_REMOVE(&files, id, next);
+					TAILQ_INSERT_TAIL(preferred, id, next);
+					id->ac = ac;
+					found = 1;
+					break;
+				}
+			}
+			if (!found) {
+				id = xmalloc(sizeof(*id));
+				memset(id, 0, sizeof(*id));
+				id->key = key;
+				id->filename = comment;
+				id->ac = ac;
+				TAILQ_INSERT_TAIL(&agent, id, next);
+			}
+		}
+		/* append remaining agent keys */
+		for (id = TAILQ_FIRST(&agent); id; id = TAILQ_FIRST(&agent)) {
+			TAILQ_REMOVE(&agent, id, next);
+			TAILQ_INSERT_TAIL(preferred, id, next);
+		}
+		authctxt->agent = ac;
+	}
+	/* append remaining keys from the config file */
+	for (id = TAILQ_FIRST(&files); id; id = TAILQ_FIRST(&files)) {
+		TAILQ_REMOVE(&files, id, next);
+		TAILQ_INSERT_TAIL(preferred, id, next);
+	}
+	TAILQ_FOREACH(id, preferred, next) {
+		debug2("key: %s (%p)", id->filename, id->key);
+	}
 }
 
-static int
-agent_sign_cb(Authctxt *authctxt, Key *key, u_char **sigp, u_int *lenp,
-    u_char *data, u_int datalen)
+static void
+pubkey_cleanup(Authctxt *authctxt)
 {
-	return ssh_agent_sign(authctxt->agent, key, sigp, lenp, data, datalen);
-}
+	Identity *id;
 
-static int
-key_sign_cb(Authctxt *authctxt, Key *key, u_char **sigp, u_int *lenp,
-    u_char *data, u_int datalen)
-{
-	return key_sign(key, sigp, lenp, data, datalen);
-}
-
-static int
-userauth_pubkey_agent(Authctxt *authctxt)
-{
-	static int called = 0;
-	int ret = 0;
-	char *comment;
-	Key *k;
-
-	if (called == 0) {
-		if (ssh_get_num_identities(authctxt->agent, 2) == 0)
-			debug2("userauth_pubkey_agent: no keys at all");
-		called = 1;
+	if (authctxt->agent != NULL)
+		ssh_close_authentication_connection(authctxt->agent);
+	for (id = TAILQ_FIRST(&authctxt->keys); id;
+	    id = TAILQ_FIRST(&authctxt->keys)) {
+		TAILQ_REMOVE(&authctxt->keys, id, next);
+		if (id->key)
+			key_free(id->key);
+		if (id->filename)
+			xfree(id->filename);
+		xfree(id);
 	}
-	k = ssh_get_next_identity(authctxt->agent, &comment, 2);
-	if (k == NULL) {
-		debug2("userauth_pubkey_agent: no more keys");
-	} else {
-		debug("Offering agent key: %s", comment);
-		xfree(comment);
-		ret = send_pubkey_test(authctxt, k, agent_sign_cb, -1);
-		if (ret == 0)
-			key_free(k);
-	}
-	if (ret == 0)
-		debug2("userauth_pubkey_agent: no message sent");
-	return ret;
 }
 
 int
 userauth_pubkey(Authctxt *authctxt)
 {
-	static int idx = 0;
+	Identity *id;
 	int sent = 0;
-	Key *key;
-	char *filename;
 
-	if (authctxt->agent != NULL) {
-		do {
-			sent = userauth_pubkey_agent(authctxt);
-		} while (!sent && authctxt->agent->howmany > 0);
-	}
-	while (!sent && idx < options.num_identity_files) {
-		key = options.identity_keys[idx];
-		filename = options.identity_files[idx];
-		if (key == NULL) {
-			debug("Trying private key: %s", filename);
-			key = load_identity_file(filename);
-			if (key != NULL) {
-				sent = sign_and_send_pubkey(authctxt, key,
-				    key_sign_cb);
-				key_free(key);
+	while ((id = TAILQ_FIRST(&authctxt->keys))) {
+		if (id->tried++)
+			return (0);
+		TAILQ_REMOVE(&authctxt->keys, id, next);
+		TAILQ_INSERT_TAIL(&authctxt->keys, id, next);
+		/*
+		 * send a test message if we have the public key. for
+		 * encrypted keys we cannot do this and have to load the
+		 * private key instead
+		 */
+		if (id->key && id->key->type != KEY_RSA1) {
+			debug("Offering public key: %s", id->filename);
+			sent = send_pubkey_test(authctxt, id);
+		} else if (id->key == NULL) {
+			debug("Trying private key: %s", id->filename);
+			id->key = load_identity_file(id->filename);
+			if (id->key != NULL) {
+				id->isprivate = 1;
+				sent = sign_and_send_pubkey(authctxt, id);
+				key_free(id->key);
+				id->key = NULL;
 			}
-		} else if (key->type != KEY_RSA1) {
-			debug("Offering public key: %s", filename);
-			sent = send_pubkey_test(authctxt, key,
-			    identity_sign_cb, idx);
 		}
-		idx++;
+		if (sent)
+			return (sent);
 	}
-	return sent;
+	return (0);
 }
 
 /*