diff --git a/ChangeLog b/ChangeLog index 795bae3c4..f02114c01 100644 --- a/ChangeLog +++ b/ChangeLog @@ -45,6 +45,14 @@ - markus@cvs.openbsd.org 2003/05/11 20:30:25 [channels.c clientloop.c serverloop.c session.c ssh.c] make channel_new() strdup the 'remote_name' (not the caller); ok theo + - markus@cvs.openbsd.org 2003/05/12 16:55:37 + [sshconnect2.c] + for pubkey authentication try the user 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 + this helps when an agent has many keys, where the server might + close the connection before the correct key is used. report & ok pb@ 20030512 - (djm) Redhat spec: Don't install profile.d scripts when not @@ -1432,4 +1440,4 @@ save auth method before monitor_reset_key_state(); bugzilla bug #284; ok provos@ -$Id: ChangeLog,v 1.2688 2003/05/14 03:45:42 djm Exp $ +$Id: ChangeLog,v 1.2689 2003/05/14 03:46:00 djm Exp $ diff --git a/sshconnect2.c b/sshconnect2.c index d32960447..74d699ff2 100644 --- a/sshconnect2.c +++ b/sshconnect2.c @@ -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 @@ ssh_kex2(char *host, struct sockaddr *hostaddr) 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 @@ struct Authctxt { 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 @@ int userauth_hostbased(Authctxt *); 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 @@ ssh_userauth2(const char *local_user, const char *server_user, char *host, /* 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 @@ ssh_userauth2(const char *local_user, const char *server_user, char *host, 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 @@ input_userauth_pk_ok(int type, u_int32_t seq, void *ctxt) { Authctxt *authctxt = ctxt; Key *key = NULL; + Identity *id = NULL; Buffer b; int pktype, sent = 0; u_int alen, blen; @@ -382,40 +390,33 @@ input_userauth_pk_ok(int type, u_int32_t seq, void *ctxt) } 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"); - 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); + 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; + } + } +done: if (key != NULL) key_free(key); xfree(pkalg); @@ -428,7 +429,6 @@ input_userauth_pk_ok(int type, u_int32_t seq, void *ctxt) /* try another method if we did not send a packet */ if (sent == 0) userauth(authctxt, NULL); - } int @@ -547,18 +547,35 @@ clear_auth_state(Authctxt *authctxt) { /* 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 -sign_and_send_pubkey(Authctxt *authctxt, Key *k, sign_cb_fn *sign_callback) +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, Identity *id) { Buffer b; u_char *blob, *signature; @@ -569,7 +586,7 @@ sign_and_send_pubkey(Authctxt *authctxt, Key *k, sign_cb_fn *sign_callback) 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 @@ sign_and_send_pubkey(Authctxt *authctxt, Key *k, sign_cb_fn *sign_callback) } 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 @@ sign_and_send_pubkey(Authctxt *authctxt, Key *k, sign_cb_fn *sign_callback) 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 @@ sign_and_send_pubkey(Authctxt *authctxt, Key *k, sign_cb_fn *sign_callback) } 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 @@ send_pubkey_test(Authctxt *authctxt, Key *k, sign_cb_fn *sign_callback, 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 @@ load_identity_file(char *filename) 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; - - idx = authctxt->last_key_hint; - if (idx < 0) - return -1; - - /* 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; -} - -static int -agent_sign_cb(Authctxt *authctxt, Key *key, u_char **sigp, u_int *lenp, - u_char *data, u_int datalen) -{ - return ssh_agent_sign(authctxt->agent, key, sigp, lenp, data, datalen); -} - -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; + Identity *id; + Idlist agent, files, *preferred; + Key *key; + AuthenticationConnection *ac; char *comment; - Key *k; + int i, found; - if (called == 0) { - if (ssh_get_num_identities(authctxt->agent, 2) == 0) - debug2("userauth_pubkey_agent: no keys at all"); - called = 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 */ + + /* 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); } - 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); + /* 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 void +pubkey_cleanup(Authctxt *authctxt) +{ + Identity *id; + + 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); } - 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); } /*