diff options
Diffstat (limited to 'ssh-agent.c')
| -rw-r--r-- | ssh-agent.c | 2468 |
1 files changed, 2468 insertions, 0 deletions
diff --git a/ssh-agent.c b/ssh-agent.c new file mode 100644 index 0000000..b6a3f48 --- /dev/null +++ b/ssh-agent.c @@ -0,0 +1,2468 @@ +/* $OpenBSD: ssh-agent.c,v 1.303 2023/12/18 14:48:08 djm Exp $ */ +/* + * Author: Tatu Ylonen <ylo@cs.hut.fi> + * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland + * All rights reserved + * The authentication agent program. + * + * 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". + * + * Copyright (c) 2000, 2001 Markus Friedl. All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 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. + * + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR + * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES + * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. + * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, + * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT + * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, + * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY + * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT + * (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" + +#include <sys/types.h> +#include <sys/resource.h> +#include <sys/stat.h> +#include <sys/socket.h> +#include <sys/wait.h> +#ifdef HAVE_SYS_TIME_H +# include <sys/time.h> +#endif +#ifdef HAVE_SYS_UN_H +# include <sys/un.h> +#endif +#include "openbsd-compat/sys-queue.h" + +#ifdef WITH_OPENSSL +#include <openssl/evp.h> +#include "openbsd-compat/openssl-compat.h" +#endif + +#include <errno.h> +#include <fcntl.h> +#include <limits.h> +#ifdef HAVE_PATHS_H +# include <paths.h> +#endif +#ifdef HAVE_POLL_H +# include <poll.h> +#endif +#include <signal.h> +#include <stdarg.h> +#include <stdio.h> +#include <stdlib.h> +#include <time.h> +#include <string.h> +#include <unistd.h> +#ifdef HAVE_UTIL_H +# include <util.h> +#endif + +#include "xmalloc.h" +#include "ssh.h" +#include "ssh2.h" +#include "sshbuf.h" +#include "sshkey.h" +#include "authfd.h" +#include "log.h" +#include "misc.h" +#include "digest.h" +#include "ssherr.h" +#include "match.h" +#include "msg.h" +#include "pathnames.h" +#include "ssh-pkcs11.h" +#include "sk-api.h" +#include "myproposal.h" + +#ifndef DEFAULT_ALLOWED_PROVIDERS +# define DEFAULT_ALLOWED_PROVIDERS "/usr/lib*/*,/usr/local/lib*/*" +#endif + +/* Maximum accepted message length */ +#define AGENT_MAX_LEN (256*1024) +/* Maximum bytes to read from client socket */ +#define AGENT_RBUF_LEN (4096) +/* Maximum number of recorded session IDs/hostkeys per connection */ +#define AGENT_MAX_SESSION_IDS 16 +/* Maximum size of session ID */ +#define AGENT_MAX_SID_LEN 128 +/* Maximum number of destination constraints to accept on a key */ +#define AGENT_MAX_DEST_CONSTRAINTS 1024 +/* Maximum number of associated certificate constraints to accept on a key */ +#define AGENT_MAX_EXT_CERTS 1024 + +/* XXX store hostkey_sid in a refcounted tree */ + +typedef enum { + AUTH_UNUSED = 0, + AUTH_SOCKET = 1, + AUTH_CONNECTION = 2, +} sock_type; + +struct hostkey_sid { + struct sshkey *key; + struct sshbuf *sid; + int forwarded; +}; + +typedef struct socket_entry { + int fd; + sock_type type; + struct sshbuf *input; + struct sshbuf *output; + struct sshbuf *request; + size_t nsession_ids; + struct hostkey_sid *session_ids; + int session_bind_attempted; +} SocketEntry; + +u_int sockets_alloc = 0; +SocketEntry *sockets = NULL; + +typedef struct identity { + TAILQ_ENTRY(identity) next; + struct sshkey *key; + char *comment; + char *provider; + time_t death; + u_int confirm; + char *sk_provider; + struct dest_constraint *dest_constraints; + size_t ndest_constraints; +} Identity; + +struct idtable { + int nentries; + TAILQ_HEAD(idqueue, identity) idlist; +}; + +/* private key table */ +struct idtable *idtab; + +int max_fd = 0; + +/* pid of shell == parent of agent */ +pid_t parent_pid = -1; +time_t parent_alive_interval = 0; + +/* pid of process for which cleanup_socket is applicable */ +pid_t cleanup_pid = 0; + +/* pathname and directory for AUTH_SOCKET */ +char socket_name[PATH_MAX]; +char socket_dir[PATH_MAX]; + +/* Pattern-list of allowed PKCS#11/Security key paths */ +static char *allowed_providers; + +/* + * Allows PKCS11 providers or SK keys that use non-internal providers to + * be added over a remote connection (identified by session-bind@openssh.com). + */ +static int remote_add_provider; + +/* locking */ +#define LOCK_SIZE 32 +#define LOCK_SALT_SIZE 16 +#define LOCK_ROUNDS 1 +int locked = 0; +u_char lock_pwhash[LOCK_SIZE]; +u_char lock_salt[LOCK_SALT_SIZE]; + +extern char *__progname; + +/* Default lifetime in seconds (0 == forever) */ +static int lifetime = 0; + +static int fingerprint_hash = SSH_FP_HASH_DEFAULT; + +/* Refuse signing of non-SSH messages for web-origin FIDO keys */ +static int restrict_websafe = 1; + +static void +close_socket(SocketEntry *e) +{ + size_t i; + + close(e->fd); + sshbuf_free(e->input); + sshbuf_free(e->output); + sshbuf_free(e->request); + for (i = 0; i < e->nsession_ids; i++) { + sshkey_free(e->session_ids[i].key); + sshbuf_free(e->session_ids[i].sid); + } + free(e->session_ids); + memset(e, '\0', sizeof(*e)); + e->fd = -1; + e->type = AUTH_UNUSED; +} + +static void +idtab_init(void) +{ + idtab = xcalloc(1, sizeof(*idtab)); + TAILQ_INIT(&idtab->idlist); + idtab->nentries = 0; +} + +static void +free_dest_constraint_hop(struct dest_constraint_hop *dch) +{ + u_int i; + + if (dch == NULL) + return; + free(dch->user); + free(dch->hostname); + for (i = 0; i < dch->nkeys; i++) + sshkey_free(dch->keys[i]); + free(dch->keys); + free(dch->key_is_ca); +} + +static void +free_dest_constraints(struct dest_constraint *dcs, size_t ndcs) +{ + size_t i; + + for (i = 0; i < ndcs; i++) { + free_dest_constraint_hop(&dcs[i].from); + free_dest_constraint_hop(&dcs[i].to); + } + free(dcs); +} + +static void +dup_dest_constraint_hop(const struct dest_constraint_hop *dch, + struct dest_constraint_hop *out) +{ + u_int i; + int r; + + out->user = dch->user == NULL ? NULL : xstrdup(dch->user); + out->hostname = dch->hostname == NULL ? NULL : xstrdup(dch->hostname); + out->is_ca = dch->is_ca; + out->nkeys = dch->nkeys; + out->keys = out->nkeys == 0 ? NULL : + xcalloc(out->nkeys, sizeof(*out->keys)); + out->key_is_ca = out->nkeys == 0 ? NULL : + xcalloc(out->nkeys, sizeof(*out->key_is_ca)); + for (i = 0; i < dch->nkeys; i++) { + if (dch->keys[i] != NULL && + (r = sshkey_from_private(dch->keys[i], + &(out->keys[i]))) != 0) + fatal_fr(r, "copy key"); + out->key_is_ca[i] = dch->key_is_ca[i]; + } +} + +static struct dest_constraint * +dup_dest_constraints(const struct dest_constraint *dcs, size_t ndcs) +{ + size_t i; + struct dest_constraint *ret; + + if (ndcs == 0) + return NULL; + ret = xcalloc(ndcs, sizeof(*ret)); + for (i = 0; i < ndcs; i++) { + dup_dest_constraint_hop(&dcs[i].from, &ret[i].from); + dup_dest_constraint_hop(&dcs[i].to, &ret[i].to); + } + return ret; +} + +#ifdef DEBUG_CONSTRAINTS +static void +dump_dest_constraint_hop(const struct dest_constraint_hop *dch) +{ + u_int i; + char *fp; + + debug_f("user %s hostname %s is_ca %d nkeys %u", + dch->user == NULL ? "(null)" : dch->user, + dch->hostname == NULL ? "(null)" : dch->hostname, + dch->is_ca, dch->nkeys); + for (i = 0; i < dch->nkeys; i++) { + fp = NULL; + if (dch->keys[i] != NULL && + (fp = sshkey_fingerprint(dch->keys[i], + SSH_FP_HASH_DEFAULT, SSH_FP_DEFAULT)) == NULL) + fatal_f("fingerprint failed"); + debug_f("key %u/%u: %s%s%s key_is_ca %d", i, dch->nkeys, + dch->keys[i] == NULL ? "" : sshkey_ssh_name(dch->keys[i]), + dch->keys[i] == NULL ? "" : " ", + dch->keys[i] == NULL ? "none" : fp, + dch->key_is_ca[i]); + free(fp); + } +} +#endif /* DEBUG_CONSTRAINTS */ + +static void +dump_dest_constraints(const char *context, + const struct dest_constraint *dcs, size_t ndcs) +{ +#ifdef DEBUG_CONSTRAINTS + size_t i; + + debug_f("%s: %zu constraints", context, ndcs); + for (i = 0; i < ndcs; i++) { + debug_f("constraint %zu / %zu: from: ", i, ndcs); + dump_dest_constraint_hop(&dcs[i].from); + debug_f("constraint %zu / %zu: to: ", i, ndcs); + dump_dest_constraint_hop(&dcs[i].to); + } + debug_f("done for %s", context); +#endif /* DEBUG_CONSTRAINTS */ +} + +static void +free_identity(Identity *id) +{ + sshkey_free(id->key); + free(id->provider); + free(id->comment); + free(id->sk_provider); + free_dest_constraints(id->dest_constraints, id->ndest_constraints); + free(id); +} + +/* + * Match 'key' against the key/CA list in a destination constraint hop + * Returns 0 on success or -1 otherwise. + */ +static int +match_key_hop(const char *tag, const struct sshkey *key, + const struct dest_constraint_hop *dch) +{ + const char *reason = NULL; + const char *hostname = dch->hostname ? dch->hostname : "(ORIGIN)"; + u_int i; + char *fp; + + if (key == NULL) + return -1; + /* XXX logspam */ + if ((fp = sshkey_fingerprint(key, SSH_FP_HASH_DEFAULT, + SSH_FP_DEFAULT)) == NULL) + fatal_f("fingerprint failed"); + debug3_f("%s: entering hostname %s, requested key %s %s, %u keys avail", + tag, hostname, sshkey_type(key), fp, dch->nkeys); + free(fp); + for (i = 0; i < dch->nkeys; i++) { + if (dch->keys[i] == NULL) + return -1; + /* XXX logspam */ + if ((fp = sshkey_fingerprint(dch->keys[i], SSH_FP_HASH_DEFAULT, + SSH_FP_DEFAULT)) == NULL) + fatal_f("fingerprint failed"); + debug3_f("%s: key %u: %s%s %s", tag, i, + dch->key_is_ca[i] ? "CA " : "", + sshkey_type(dch->keys[i]), fp); + free(fp); + if (!sshkey_is_cert(key)) { + /* plain key */ + if (dch->key_is_ca[i] || + !sshkey_equal(key, dch->keys[i])) + continue; + return 0; + } + /* certificate */ + if (!dch->key_is_ca[i]) + continue; + if (key->cert == NULL || key->cert->signature_key == NULL) + return -1; /* shouldn't happen */ + if (!sshkey_equal(key->cert->signature_key, dch->keys[i])) + continue; + if (sshkey_cert_check_host(key, hostname, 1, + SSH_ALLOWED_CA_SIGALGS, &reason) != 0) { + debug_f("cert %s / hostname %s rejected: %s", + key->cert->key_id, hostname, reason); + continue; + } + return 0; + } + return -1; +} + +/* Check destination constraints on an identity against the hostkey/user */ +static int +permitted_by_dest_constraints(const struct sshkey *fromkey, + const struct sshkey *tokey, Identity *id, const char *user, + const char **hostnamep) +{ + size_t i; + struct dest_constraint *d; + + if (hostnamep != NULL) + *hostnamep = NULL; + for (i = 0; i < id->ndest_constraints; i++) { + d = id->dest_constraints + i; + /* XXX remove logspam */ + debug2_f("constraint %zu %s%s%s (%u keys) > %s%s%s (%u keys)", + i, d->from.user ? d->from.user : "", + d->from.user ? "@" : "", + d->from.hostname ? d->from.hostname : "(ORIGIN)", + d->from.nkeys, + d->to.user ? d->to.user : "", d->to.user ? "@" : "", + d->to.hostname ? d->to.hostname : "(ANY)", d->to.nkeys); + + /* Match 'from' key */ + if (fromkey == NULL) { + /* We are matching the first hop */ + if (d->from.hostname != NULL || d->from.nkeys != 0) + continue; + } else if (match_key_hop("from", fromkey, &d->from) != 0) + continue; + + /* Match 'to' key */ + if (tokey != NULL && match_key_hop("to", tokey, &d->to) != 0) + continue; + + /* Match user if specified */ + if (d->to.user != NULL && user != NULL && + !match_pattern(user, d->to.user)) + continue; + + /* successfully matched this constraint */ + if (hostnamep != NULL) + *hostnamep = d->to.hostname; + debug2_f("allowed for hostname %s", + d->to.hostname == NULL ? "*" : d->to.hostname); + return 0; + } + /* no match */ + debug2_f("%s identity \"%s\" not permitted for this destination", + sshkey_type(id->key), id->comment); + return -1; +} + +/* + * Check whether hostkeys on a SocketEntry and the optionally specified user + * are permitted by the destination constraints on the Identity. + * Returns 0 on success or -1 otherwise. + */ +static int +identity_permitted(Identity *id, SocketEntry *e, char *user, + const char **forward_hostnamep, const char **last_hostnamep) +{ + size_t i; + const char **hp; + struct hostkey_sid *hks; + const struct sshkey *fromkey = NULL; + const char *test_user; + char *fp1, *fp2; + + /* XXX remove logspam */ + debug3_f("entering: key %s comment \"%s\", %zu socket bindings, " + "%zu constraints", sshkey_type(id->key), id->comment, + e->nsession_ids, id->ndest_constraints); + if (id->ndest_constraints == 0) + return 0; /* unconstrained */ + if (e->session_bind_attempted && e->nsession_ids == 0) { + error_f("previous session bind failed on socket"); + return -1; + } + if (e->nsession_ids == 0) + return 0; /* local use */ + /* + * Walk through the hops recorded by session_id and try to find a + * constraint that satisfies each. + */ + for (i = 0; i < e->nsession_ids; i++) { + hks = e->session_ids + i; + if (hks->key == NULL) + fatal_f("internal error: no bound key"); + /* XXX remove logspam */ + fp1 = fp2 = NULL; + if (fromkey != NULL && + (fp1 = sshkey_fingerprint(fromkey, SSH_FP_HASH_DEFAULT, + SSH_FP_DEFAULT)) == NULL) + fatal_f("fingerprint failed"); + if ((fp2 = sshkey_fingerprint(hks->key, SSH_FP_HASH_DEFAULT, + SSH_FP_DEFAULT)) == NULL) + fatal_f("fingerprint failed"); + debug3_f("socketentry fd=%d, entry %zu %s, " + "from hostkey %s %s to user %s hostkey %s %s", + e->fd, i, hks->forwarded ? "FORWARD" : "AUTH", + fromkey ? sshkey_type(fromkey) : "(ORIGIN)", + fromkey ? fp1 : "", user ? user : "(ANY)", + sshkey_type(hks->key), fp2); + free(fp1); + free(fp2); + /* + * Record the hostnames for the initial forwarding and + * the final destination. + */ + hp = NULL; + if (i == e->nsession_ids - 1) + hp = last_hostnamep; + else if (i == 0) + hp = forward_hostnamep; + /* Special handling for final recorded binding */ + test_user = NULL; + if (i == e->nsession_ids - 1) { + /* Can only check user at final hop */ + test_user = user; + /* + * user is only presented for signature requests. + * If this is the case, make sure last binding is not + * for a forwarding. + */ + if (hks->forwarded && user != NULL) { + error_f("tried to sign on forwarding hop"); + return -1; + } + } else if (!hks->forwarded) { + error_f("tried to forward though signing bind"); + return -1; + } + if (permitted_by_dest_constraints(fromkey, hks->key, id, + test_user, hp) != 0) + return -1; + fromkey = hks->key; + } + /* + * Another special case: if the last bound session ID was for a + * forwarding, and this function is not being called to check a sign + * request (i.e. no 'user' supplied), then only permit the key if + * there is a permission that would allow it to be used at another + * destination. This hides keys that are allowed to be used to + * authenticate *to* a host but not permitted for *use* beyond it. + */ + hks = &e->session_ids[e->nsession_ids - 1]; + if (hks->forwarded && user == NULL && + permitted_by_dest_constraints(hks->key, NULL, id, + NULL, NULL) != 0) { + debug3_f("key permitted at host but not after"); + return -1; + } + + /* success */ + return 0; +} + +static int +socket_is_remote(SocketEntry *e) +{ + return e->session_bind_attempted || (e->nsession_ids != 0); +} + +/* return matching private key for given public key */ +static Identity * +lookup_identity(struct sshkey *key) +{ + Identity *id; + + TAILQ_FOREACH(id, &idtab->idlist, next) { + if (sshkey_equal(key, id->key)) + return (id); + } + return (NULL); +} + +/* Check confirmation of keysign request */ +static int +confirm_key(Identity *id, const char *extra) +{ + char *p; + int ret = -1; + + p = sshkey_fingerprint(id->key, fingerprint_hash, SSH_FP_DEFAULT); + if (p != NULL && + ask_permission("Allow use of key %s?\nKey fingerprint %s.%s%s", + id->comment, p, + extra == NULL ? "" : "\n", extra == NULL ? "" : extra)) + ret = 0; + free(p); + + return (ret); +} + +static void +send_status(SocketEntry *e, int success) +{ + int r; + + if ((r = sshbuf_put_u32(e->output, 1)) != 0 || + (r = sshbuf_put_u8(e->output, success ? + SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE)) != 0) + fatal_fr(r, "compose"); +} + +/* send list of supported public keys to 'client' */ +static void +process_request_identities(SocketEntry *e) +{ + Identity *id; + struct sshbuf *msg, *keys; + int r; + u_int i = 0, nentries = 0; + char *fp; + + debug2_f("entering"); + + if ((msg = sshbuf_new()) == NULL || (keys = sshbuf_new()) == NULL) + fatal_f("sshbuf_new failed"); + TAILQ_FOREACH(id, &idtab->idlist, next) { + if ((fp = sshkey_fingerprint(id->key, SSH_FP_HASH_DEFAULT, + SSH_FP_DEFAULT)) == NULL) + fatal_f("fingerprint failed"); + debug_f("key %u / %u: %s %s", i++, idtab->nentries, + sshkey_ssh_name(id->key), fp); + dump_dest_constraints(__func__, + id->dest_constraints, id->ndest_constraints); + free(fp); + /* identity not visible, don't include in response */ + if (identity_permitted(id, e, NULL, NULL, NULL) != 0) + continue; + if ((r = sshkey_puts_opts(id->key, keys, + SSHKEY_SERIALIZE_INFO)) != 0 || + (r = sshbuf_put_cstring(keys, id->comment)) != 0) { + error_fr(r, "compose key/comment"); + continue; + } + nentries++; + } + debug2_f("replying with %u allowed of %u available keys", + nentries, idtab->nentries); + if ((r = sshbuf_put_u8(msg, SSH2_AGENT_IDENTITIES_ANSWER)) != 0 || + (r = sshbuf_put_u32(msg, nentries)) != 0 || + (r = sshbuf_putb(msg, keys)) != 0) + fatal_fr(r, "compose"); + if ((r = sshbuf_put_stringb(e->output, msg)) != 0) + fatal_fr(r, "enqueue"); + sshbuf_free(msg); + sshbuf_free(keys); +} + + +static char * +agent_decode_alg(struct sshkey *key, u_int flags) +{ + if (key->type == KEY_RSA) { + if (flags & SSH_AGENT_RSA_SHA2_256) + return "rsa-sha2-256"; + else if (flags & SSH_AGENT_RSA_SHA2_512) + return "rsa-sha2-512"; + } else if (key->type == KEY_RSA_CERT) { + if (flags & SSH_AGENT_RSA_SHA2_256) + return "rsa-sha2-256-cert-v01@openssh.com"; + else if (flags & SSH_AGENT_RSA_SHA2_512) + return "rsa-sha2-512-cert-v01@openssh.com"; + } + return NULL; +} + +/* + * Attempt to parse the contents of a buffer as a SSH publickey userauth + * request, checking its contents for consistency and matching the embedded + * key against the one that is being used for signing. + * Note: does not modify msg buffer. + * Optionally extract the username, session ID and/or hostkey from the request. + */ +static int +parse_userauth_request(struct sshbuf *msg, const struct sshkey *expected_key, + char **userp, struct sshbuf **sess_idp, struct sshkey **hostkeyp) +{ + struct sshbuf *b = NULL, *sess_id = NULL; + char *user = NULL, *service = NULL, *method = NULL, *pkalg = NULL; + int r; + u_char t, sig_follows; + struct sshkey *mkey = NULL, *hostkey = NULL; + + if (userp != NULL) + *userp = NULL; + if (sess_idp != NULL) + *sess_idp = NULL; + if (hostkeyp != NULL) + *hostkeyp = NULL; + if ((b = sshbuf_fromb(msg)) == NULL) + fatal_f("sshbuf_fromb"); + + /* SSH userauth request */ + if ((r = sshbuf_froms(b, &sess_id)) != 0) + goto out; + if (sshbuf_len(sess_id) == 0) { + r = SSH_ERR_INVALID_FORMAT; + goto out; + } + if ((r = sshbuf_get_u8(b, &t)) != 0 || /* SSH2_MSG_USERAUTH_REQUEST */ + (r = sshbuf_get_cstring(b, &user, NULL)) != 0 || /* server user */ + (r = sshbuf_get_cstring(b, &service, NULL)) != 0 || /* service */ + (r = sshbuf_get_cstring(b, &method, NULL)) != 0 || /* method */ + (r = sshbuf_get_u8(b, &sig_follows)) != 0 || /* sig-follows */ + (r = sshbuf_get_cstring(b, &pkalg, NULL)) != 0 || /* alg */ + (r = sshkey_froms(b, &mkey)) != 0) /* key */ + goto out; + if (t != SSH2_MSG_USERAUTH_REQUEST || + sig_follows != 1 || + strcmp(service, "ssh-connection") != 0 || + !sshkey_equal(expected_key, mkey) || + sshkey_type_from_name(pkalg) != expected_key->type) { + r = SSH_ERR_INVALID_FORMAT; + goto out; + } + if (strcmp(method, "publickey-hostbound-v00@openssh.com") == 0) { + if ((r = sshkey_froms(b, &hostkey)) != 0) + goto out; + } else if (strcmp(method, "publickey") != 0) { + r = SSH_ERR_INVALID_FORMAT; + goto out; + } + if (sshbuf_len(b) != 0) { + r = SSH_ERR_INVALID_FORMAT; + goto out; + } + /* success */ + r = 0; + debug3_f("well formed userauth"); + if (userp != NULL) { + *userp = user; + user = NULL; + } + if (sess_idp != NULL) { + *sess_idp = sess_id; + sess_id = NULL; + } + if (hostkeyp != NULL) { + *hostkeyp = hostkey; + hostkey = NULL; + } + out: + sshbuf_free(b); + sshbuf_free(sess_id); + free(user); + free(service); + free(method); + free(pkalg); + sshkey_free(mkey); + sshkey_free(hostkey); + return r; +} + +/* + * Attempt to parse the contents of a buffer as a SSHSIG signature request. + * Note: does not modify buffer. + */ +static int +parse_sshsig_request(struct sshbuf *msg) +{ + int r; + struct sshbuf *b; + + if ((b = sshbuf_fromb(msg)) == NULL) + fatal_f("sshbuf_fromb"); + + if ((r = sshbuf_cmp(b, 0, "SSHSIG", 6)) != 0 || + (r = sshbuf_consume(b, 6)) != 0 || + (r = sshbuf_get_cstring(b, NULL, NULL)) != 0 || /* namespace */ + (r = sshbuf_get_string_direct(b, NULL, NULL)) != 0 || /* reserved */ + (r = sshbuf_get_cstring(b, NULL, NULL)) != 0 || /* hashalg */ + (r = sshbuf_get_string_direct(b, NULL, NULL)) != 0) /* H(msg) */ + goto out; + if (sshbuf_len(b) != 0) { + r = SSH_ERR_INVALID_FORMAT; + goto out; + } + /* success */ + r = 0; + out: + sshbuf_free(b); + return r; +} + +/* + * This function inspects a message to be signed by a FIDO key that has a + * web-like application string (i.e. one that does not begin with "ssh:". + * It checks that the message is one of those expected for SSH operations + * (pubkey userauth, sshsig, CA key signing) to exclude signing challenges + * for the web. + */ +static int +check_websafe_message_contents(struct sshkey *key, struct sshbuf *data) +{ + if (parse_userauth_request(data, key, NULL, NULL, NULL) == 0) { + debug_f("signed data matches public key userauth request"); + return 1; + } + if (parse_sshsig_request(data) == 0) { + debug_f("signed data matches SSHSIG signature request"); + return 1; + } + + /* XXX check CA signature operation */ + + error("web-origin key attempting to sign non-SSH message"); + return 0; +} + +static int +buf_equal(const struct sshbuf *a, const struct sshbuf *b) +{ + if (sshbuf_ptr(a) == NULL || sshbuf_ptr(b) == NULL) + return SSH_ERR_INVALID_ARGUMENT; + if (sshbuf_len(a) != sshbuf_len(b)) + return SSH_ERR_INVALID_FORMAT; + if (timingsafe_bcmp(sshbuf_ptr(a), sshbuf_ptr(b), sshbuf_len(a)) != 0) + return SSH_ERR_INVALID_FORMAT; + return 0; +} + +/* ssh2 only */ +static void +process_sign_request2(SocketEntry *e) +{ + u_char *signature = NULL; + size_t slen = 0; + u_int compat = 0, flags; + int r, ok = -1, retried = 0; + char *fp = NULL, *pin = NULL, *prompt = NULL; + char *user = NULL, *sig_dest = NULL; + const char *fwd_host = NULL, *dest_host = NULL; + struct sshbuf *msg = NULL, *data = NULL, *sid = NULL; + struct sshkey *key = NULL, *hostkey = NULL; + struct identity *id; + struct notifier_ctx *notifier = NULL; + + debug_f("entering"); + + if ((msg = sshbuf_new()) == NULL || (data = sshbuf_new()) == NULL) + fatal_f("sshbuf_new failed"); + if ((r = sshkey_froms(e->request, &key)) != 0 || + (r = sshbuf_get_stringb(e->request, data)) != 0 || + (r = sshbuf_get_u32(e->request, &flags)) != 0) { + error_fr(r, "parse"); + goto send; + } + + if ((id = lookup_identity(key)) == NULL) { + verbose_f("%s key not found", sshkey_type(key)); + goto send; + } + if ((fp = sshkey_fingerprint(key, SSH_FP_HASH_DEFAULT, + SSH_FP_DEFAULT)) == NULL) + fatal_f("fingerprint failed"); + + if (id->ndest_constraints != 0) { + if (e->nsession_ids == 0) { + logit_f("refusing use of destination-constrained key " + "to sign on unbound connection"); + goto send; + } + if (parse_userauth_request(data, key, &user, &sid, + &hostkey) != 0) { + logit_f("refusing use of destination-constrained key " + "to sign an unidentified signature"); + goto send; + } + /* XXX logspam */ + debug_f("user=%s", user); + if (identity_permitted(id, e, user, &fwd_host, &dest_host) != 0) + goto send; + /* XXX display fwd_host/dest_host in askpass UI */ + /* + * Ensure that the session ID is the most recent one + * registered on the socket - it should have been bound by + * ssh immediately before userauth. + */ + if (buf_equal(sid, + e->session_ids[e->nsession_ids - 1].sid) != 0) { + error_f("unexpected session ID (%zu listed) on " + "signature request for target user %s with " + "key %s %s", e->nsession_ids, user, + sshkey_type(id->key), fp); + goto send; + } + /* + * Ensure that the hostkey embedded in the signature matches + * the one most recently bound to the socket. An exception is + * made for the initial forwarding hop. + */ + if (e->nsession_ids > 1 && hostkey == NULL) { + error_f("refusing use of destination-constrained key: " + "no hostkey recorded in signature for forwarded " + "connection"); + goto send; + } + if (hostkey != NULL && !sshkey_equal(hostkey, + e->session_ids[e->nsession_ids - 1].key)) { + error_f("refusing use of destination-constrained key: " + "mismatch between hostkey in request and most " + "recently bound session"); + goto send; + } + xasprintf(&sig_dest, "public key authentication request for " + "user \"%s\" to listed host", user); + } + if (id->confirm && confirm_key(id, sig_dest) != 0) { + verbose_f("user refused key"); + goto send; + } + if (sshkey_is_sk(id->key)) { + if (restrict_websafe && + strncmp(id->key->sk_application, "ssh:", 4) != 0 && + !check_websafe_message_contents(key, data)) { + /* error already logged */ + goto send; + } + if (id->key->sk_flags & SSH_SK_USER_PRESENCE_REQD) { + notifier = notify_start(0, + "Confirm user presence for key %s %s%s%s", + sshkey_type(id->key), fp, + sig_dest == NULL ? "" : "\n", + sig_dest == NULL ? "" : sig_dest); + } + } + retry_pin: + if ((r = sshkey_sign(id->key, &signature, &slen, + sshbuf_ptr(data), sshbuf_len(data), agent_decode_alg(key, flags), + id->sk_provider, pin, compat)) != 0) { + debug_fr(r, "sshkey_sign"); + if (pin == NULL && !retried && sshkey_is_sk(id->key) && + r == SSH_ERR_KEY_WRONG_PASSPHRASE) { + notify_complete(notifier, NULL); + notifier = NULL; + /* XXX include sig_dest */ + xasprintf(&prompt, "Enter PIN%sfor %s key %s: ", + (id->key->sk_flags & SSH_SK_USER_PRESENCE_REQD) ? + " and confirm user presence " : " ", + sshkey_type(id->key), fp); + pin = read_passphrase(prompt, RP_USE_ASKPASS); + retried = 1; + goto retry_pin; + } + error_fr(r, "sshkey_sign"); + goto send; + } + /* Success */ + ok = 0; + debug_f("good signature"); + send: + notify_complete(notifier, "User presence confirmed"); + + if (ok == 0) { + if ((r = sshbuf_put_u8(msg, SSH2_AGENT_SIGN_RESPONSE)) != 0 || + (r = sshbuf_put_string(msg, signature, slen)) != 0) + fatal_fr(r, "compose"); + } else if ((r = sshbuf_put_u8(msg, SSH_AGENT_FAILURE)) != 0) + fatal_fr(r, "compose failure"); + + if ((r = sshbuf_put_stringb(e->output, msg)) != 0) + fatal_fr(r, "enqueue"); + + sshbuf_free(sid); + sshbuf_free(data); + sshbuf_free(msg); + sshkey_free(key); + sshkey_free(hostkey); + free(fp); + free(signature); + free(sig_dest); + free(user); + free(prompt); + if (pin != NULL) + freezero(pin, strlen(pin)); +} + +/* shared */ +static void +process_remove_identity(SocketEntry *e) +{ + int r, success = 0; + struct sshkey *key = NULL; + Identity *id; + + debug2_f("entering"); + if ((r = sshkey_froms(e->request, &key)) != 0) { + error_fr(r, "parse key"); + goto done; + } + if ((id = lookup_identity(key)) == NULL) { + debug_f("key not found"); + goto done; + } + /* identity not visible, cannot be removed */ + if (identity_permitted(id, e, NULL, NULL, NULL) != 0) + goto done; /* error already logged */ + /* We have this key, free it. */ + if (idtab->nentries < 1) + fatal_f("internal error: nentries %d", idtab->nentries); + TAILQ_REMOVE(&idtab->idlist, id, next); + free_identity(id); + idtab->nentries--; + success = 1; + done: + sshkey_free(key); + send_status(e, success); +} + +static void +process_remove_all_identities(SocketEntry *e) +{ + Identity *id; + + debug2_f("entering"); + /* Loop over all identities and clear the keys. */ + for (id = TAILQ_FIRST(&idtab->idlist); id; + id = TAILQ_FIRST(&idtab->idlist)) { + TAILQ_REMOVE(&idtab->idlist, id, next); + free_identity(id); + } + + /* Mark that there are no identities. */ + idtab->nentries = 0; + + /* Send success. */ + send_status(e, 1); +} + +/* removes expired keys and returns number of seconds until the next expiry */ +static time_t +reaper(void) +{ + time_t deadline = 0, now = monotime(); + Identity *id, *nxt; + + for (id = TAILQ_FIRST(&idtab->idlist); id; id = nxt) { + nxt = TAILQ_NEXT(id, next); + if (id->death == 0) + continue; + if (now >= id->death) { + debug("expiring key '%s'", id->comment); + TAILQ_REMOVE(&idtab->idlist, id, next); + free_identity(id); + idtab->nentries--; + } else + deadline = (deadline == 0) ? id->death : + MINIMUM(deadline, id->death); + } + if (deadline == 0 || deadline <= now) + return 0; + else + return (deadline - now); +} + +static int +parse_dest_constraint_hop(struct sshbuf *b, struct dest_constraint_hop *dch) +{ + u_char key_is_ca; + size_t elen = 0; + int r; + struct sshkey *k = NULL; + char *fp; + + memset(dch, '\0', sizeof(*dch)); + if ((r = sshbuf_get_cstring(b, &dch->user, NULL)) != 0 || + (r = sshbuf_get_cstring(b, &dch->hostname, NULL)) != 0 || + (r = sshbuf_get_string_direct(b, NULL, &elen)) != 0) { + error_fr(r, "parse"); + goto out; + } + if (elen != 0) { + error_f("unsupported extensions (len %zu)", elen); + r = SSH_ERR_FEATURE_UNSUPPORTED; + goto out; + } + if (*dch->hostname == '\0') { + free(dch->hostname); + dch->hostname = NULL; + } + if (*dch->user == '\0') { + free(dch->user); + dch->user = NULL; + } + while (sshbuf_len(b) != 0) { + dch->keys = xrecallocarray(dch->keys, dch->nkeys, + dch->nkeys + 1, sizeof(*dch->keys)); + dch->key_is_ca = xrecallocarray(dch->key_is_ca, dch->nkeys, + dch->nkeys + 1, sizeof(*dch->key_is_ca)); + if ((r = sshkey_froms(b, &k)) != 0 || + (r = sshbuf_get_u8(b, &key_is_ca)) != 0) + goto out; + if ((fp = sshkey_fingerprint(k, SSH_FP_HASH_DEFAULT, + SSH_FP_DEFAULT)) == NULL) + fatal_f("fingerprint failed"); + debug3_f("%s%s%s: adding %skey %s %s", + dch->user == NULL ? "" : dch->user, + dch->user == NULL ? "" : "@", + dch->hostname, key_is_ca ? "CA " : "", sshkey_type(k), fp); + free(fp); + dch->keys[dch->nkeys] = k; + dch->key_is_ca[dch->nkeys] = key_is_ca != 0; + dch->nkeys++; + k = NULL; /* transferred */ + } + /* success */ + r = 0; + out: + sshkey_free(k); + return r; +} + +static int +parse_dest_constraint(struct sshbuf *m, struct dest_constraint *dc) +{ + struct sshbuf *b = NULL, *frombuf = NULL, *tobuf = NULL; + int r; + size_t elen = 0; + + debug3_f("entering"); + + memset(dc, '\0', sizeof(*dc)); + if ((r = sshbuf_froms(m, &b)) != 0 || + (r = sshbuf_froms(b, &frombuf)) != 0 || + (r = sshbuf_froms(b, &tobuf)) != 0 || + (r = sshbuf_get_string_direct(b, NULL, &elen)) != 0) { + error_fr(r, "parse"); + goto out; + } + if ((r = parse_dest_constraint_hop(frombuf, &dc->from)) != 0 || + (r = parse_dest_constraint_hop(tobuf, &dc->to)) != 0) + goto out; /* already logged */ + if (elen != 0) { + error_f("unsupported extensions (len %zu)", elen); + r = SSH_ERR_FEATURE_UNSUPPORTED; + goto out; + } + debug2_f("parsed %s (%u keys) > %s%s%s (%u keys)", + dc->from.hostname ? dc->from.hostname : "(ORIGIN)", dc->from.nkeys, + dc->to.user ? dc->to.user : "", dc->to.user ? "@" : "", + dc->to.hostname ? dc->to.hostname : "(ANY)", dc->to.nkeys); + /* check consistency */ + if ((dc->from.hostname == NULL) != (dc->from.nkeys == 0) || + dc->from.user != NULL) { + error_f("inconsistent \"from\" specification"); + r = SSH_ERR_INVALID_FORMAT; + goto out; + } + if (dc->to.hostname == NULL || dc->to.nkeys == 0) { + error_f("incomplete \"to\" specification"); + r = SSH_ERR_INVALID_FORMAT; + goto out; + } + /* success */ + r = 0; + out: + sshbuf_free(b); + sshbuf_free(frombuf); + sshbuf_free(tobuf); + return r; +} + +static int +parse_key_constraint_extension(struct sshbuf *m, char **sk_providerp, + struct dest_constraint **dcsp, size_t *ndcsp, int *cert_onlyp, + struct sshkey ***certs, size_t *ncerts) +{ + char *ext_name = NULL; + int r; + struct sshbuf *b = NULL; + u_char v; + struct sshkey *k; + + if ((r = sshbuf_get_cstring(m, &ext_name, NULL)) != 0) { + error_fr(r, "parse constraint extension"); + goto out; + } + debug_f("constraint ext %s", ext_name); + if (strcmp(ext_name, "sk-provider@openssh.com") == 0) { + if (sk_providerp == NULL) { + error_f("%s not valid here", ext_name); + r = SSH_ERR_INVALID_FORMAT; + goto out; + } + if (*sk_providerp != NULL) { + error_f("%s already set", ext_name); + r = SSH_ERR_INVALID_FORMAT; + goto out; + } + if ((r = sshbuf_get_cstring(m, sk_providerp, NULL)) != 0) { + error_fr(r, "parse %s", ext_name); + goto out; + } + } else if (strcmp(ext_name, + "restrict-destination-v00@openssh.com") == 0) { + if (*dcsp != NULL) { + error_f("%s already set", ext_name); + goto out; + } + if ((r = sshbuf_froms(m, &b)) != 0) { + error_fr(r, "parse %s outer", ext_name); + goto out; + } + while (sshbuf_len(b) != 0) { + if (*ndcsp >= AGENT_MAX_DEST_CONSTRAINTS) { + error_f("too many %s constraints", ext_name); + goto out; + } + *dcsp = xrecallocarray(*dcsp, *ndcsp, *ndcsp + 1, + sizeof(**dcsp)); + if ((r = parse_dest_constraint(b, + *dcsp + (*ndcsp)++)) != 0) + goto out; /* error already logged */ + } + } else if (strcmp(ext_name, + "associated-certs-v00@openssh.com") == 0) { + if (certs == NULL || ncerts == NULL || cert_onlyp == NULL) { + error_f("%s not valid here", ext_name); + r = SSH_ERR_INVALID_FORMAT; + goto out; + } + if (*certs != NULL) { + error_f("%s already set", ext_name); + goto out; + } + if ((r = sshbuf_get_u8(m, &v)) != 0 || + (r = sshbuf_froms(m, &b)) != 0) { + error_fr(r, "parse %s", ext_name); + goto out; + } + *cert_onlyp = v != 0; + while (sshbuf_len(b) != 0) { + if (*ncerts >= AGENT_MAX_EXT_CERTS) { + error_f("too many %s constraints", ext_name); + goto out; + } + *certs = xrecallocarray(*certs, *ncerts, *ncerts + 1, + sizeof(**certs)); + if ((r = sshkey_froms(b, &k)) != 0) { + error_fr(r, "parse key"); + goto out; + } + (*certs)[(*ncerts)++] = k; + } + } else { + error_f("unsupported constraint \"%s\"", ext_name); + r = SSH_ERR_FEATURE_UNSUPPORTED; + goto out; + } + /* success */ + r = 0; + out: + free(ext_name); + sshbuf_free(b); + return r; +} + +static int +parse_key_constraints(struct sshbuf *m, struct sshkey *k, time_t *deathp, + u_int *secondsp, int *confirmp, char **sk_providerp, + struct dest_constraint **dcsp, size_t *ndcsp, + int *cert_onlyp, size_t *ncerts, struct sshkey ***certs) +{ + u_char ctype; + int r; + u_int seconds, maxsign = 0; + + while (sshbuf_len(m)) { + if ((r = sshbuf_get_u8(m, &ctype)) != 0) { + error_fr(r, "parse constraint type"); + goto out; + } + switch (ctype) { + case SSH_AGENT_CONSTRAIN_LIFETIME: + if (*deathp != 0) { + error_f("lifetime already set"); + r = SSH_ERR_INVALID_FORMAT; + goto out; + } + if ((r = sshbuf_get_u32(m, &seconds)) != 0) { + error_fr(r, "parse lifetime constraint"); + goto out; + } + *deathp = monotime() + seconds; + *secondsp = seconds; + break; + case SSH_AGENT_CONSTRAIN_CONFIRM: + if (*confirmp != 0) { + error_f("confirm already set"); + r = SSH_ERR_INVALID_FORMAT; + goto out; + } + *confirmp = 1; + break; + case SSH_AGENT_CONSTRAIN_MAXSIGN: + if (k == NULL) { + error_f("maxsign not valid here"); + r = SSH_ERR_INVALID_FORMAT; + goto out; + } + if (maxsign != 0) { + error_f("maxsign already set"); + r = SSH_ERR_INVALID_FORMAT; + goto out; + } + if ((r = sshbuf_get_u32(m, &maxsign)) != 0) { + error_fr(r, "parse maxsign constraint"); + goto out; + } + if ((r = sshkey_enable_maxsign(k, maxsign)) != 0) { + error_fr(r, "enable maxsign"); + goto out; + } + break; + case SSH_AGENT_CONSTRAIN_EXTENSION: + if ((r = parse_key_constraint_extension(m, + sk_providerp, dcsp, ndcsp, + cert_onlyp, certs, ncerts)) != 0) + goto out; /* error already logged */ + break; + default: + error_f("Unknown constraint %d", ctype); + r = SSH_ERR_FEATURE_UNSUPPORTED; + goto out; + } + } + /* success */ + r = 0; + out: + return r; +} + +static void +process_add_identity(SocketEntry *e) +{ + Identity *id; + int success = 0, confirm = 0; + char *fp, *comment = NULL, *sk_provider = NULL; + char canonical_provider[PATH_MAX]; + time_t death = 0; + u_int seconds = 0; + struct dest_constraint *dest_constraints = NULL; + size_t ndest_constraints = 0; + struct sshkey *k = NULL; + int r = SSH_ERR_INTERNAL_ERROR; + + debug2_f("entering"); + if ((r = sshkey_private_deserialize(e->request, &k)) != 0 || + k == NULL || + (r = sshbuf_get_cstring(e->request, &comment, NULL)) != 0) { + error_fr(r, "parse"); + goto out; + } + if (parse_key_constraints(e->request, k, &death, &seconds, &confirm, + &sk_provider, &dest_constraints, &ndest_constraints, + NULL, NULL, NULL) != 0) { + error_f("failed to parse constraints"); + sshbuf_reset(e->request); + goto out; + } + dump_dest_constraints(__func__, dest_constraints, ndest_constraints); + + if (sk_provider != NULL) { + if (!sshkey_is_sk(k)) { + error("Cannot add provider: %s is not an " + "authenticator-hosted key", sshkey_type(k)); + goto out; + } + if (strcasecmp(sk_provider, "internal") == 0) { + debug_f("internal provider"); + } else { + if (socket_is_remote(e) && !remote_add_provider) { + verbose("failed add of SK provider \"%.100s\": " + "remote addition of providers is disabled", + sk_provider); + goto out; + } + if (realpath(sk_provider, canonical_provider) == NULL) { + verbose("failed provider \"%.100s\": " + "realpath: %s", sk_provider, + strerror(errno)); + goto out; + } + free(sk_provider); + sk_provider = xstrdup(canonical_provider); + if (match_pattern_list(sk_provider, + allowed_providers, 0) != 1) { + error("Refusing add key: " + "provider %s not allowed", sk_provider); + goto out; + } + } + } + if ((r = sshkey_shield_private(k)) != 0) { + error_fr(r, "shield private"); + goto out; + } + if (lifetime && !death) + death = monotime() + lifetime; + if ((id = lookup_identity(k)) == NULL) { + id = xcalloc(1, sizeof(Identity)); + TAILQ_INSERT_TAIL(&idtab->idlist, id, next); + /* Increment the number of identities. */ + idtab->nentries++; + } else { + /* identity not visible, do not update */ + if (identity_permitted(id, e, NULL, NULL, NULL) != 0) + goto out; /* error already logged */ + /* key state might have been updated */ + sshkey_free(id->key); + free(id->comment); + free(id->sk_provider); + free_dest_constraints(id->dest_constraints, + id->ndest_constraints); + } + /* success */ + id->key = k; + id->comment = comment; + id->death = death; + id->confirm = confirm; + id->sk_provider = sk_provider; + id->dest_constraints = dest_constraints; + id->ndest_constraints = ndest_constraints; + + if ((fp = sshkey_fingerprint(k, SSH_FP_HASH_DEFAULT, + SSH_FP_DEFAULT)) == NULL) + fatal_f("sshkey_fingerprint failed"); + debug_f("add %s %s \"%.100s\" (life: %u) (confirm: %u) " + "(provider: %s) (destination constraints: %zu)", + sshkey_ssh_name(k), fp, comment, seconds, confirm, + sk_provider == NULL ? "none" : sk_provider, ndest_constraints); + free(fp); + /* transferred */ + k = NULL; + comment = NULL; + sk_provider = NULL; + dest_constraints = NULL; + ndest_constraints = 0; + success = 1; + out: + free(sk_provider); + free(comment); + sshkey_free(k); + free_dest_constraints(dest_constraints, ndest_constraints); + send_status(e, success); +} + +/* XXX todo: encrypt sensitive data with passphrase */ +static void +process_lock_agent(SocketEntry *e, int lock) +{ + int r, success = 0, delay; + char *passwd; + u_char passwdhash[LOCK_SIZE]; + static u_int fail_count = 0; + size_t pwlen; + + debug2_f("entering"); + /* + * This is deliberately fatal: the user has requested that we lock, + * but we can't parse their request properly. The only safe thing to + * do is abort. + */ + if ((r = sshbuf_get_cstring(e->request, &passwd, &pwlen)) != 0) + fatal_fr(r, "parse"); + if (pwlen == 0) { + debug("empty password not supported"); + } else if (locked && !lock) { + if (bcrypt_pbkdf(passwd, pwlen, lock_salt, sizeof(lock_salt), + passwdhash, sizeof(passwdhash), LOCK_ROUNDS) < 0) + fatal("bcrypt_pbkdf"); + if (timingsafe_bcmp(passwdhash, lock_pwhash, LOCK_SIZE) == 0) { + debug("agent unlocked"); + locked = 0; + fail_count = 0; + explicit_bzero(lock_pwhash, sizeof(lock_pwhash)); + success = 1; + } else { + /* delay in 0.1s increments up to 10s */ + if (fail_count < 100) + fail_count++; + delay = 100000 * fail_count; + debug("unlock failed, delaying %0.1lf seconds", + (double)delay/1000000); + usleep(delay); + } + explicit_bzero(passwdhash, sizeof(passwdhash)); + } else if (!locked && lock) { + debug("agent locked"); + locked = 1; + arc4random_buf(lock_salt, sizeof(lock_salt)); + if (bcrypt_pbkdf(passwd, pwlen, lock_salt, sizeof(lock_salt), + lock_pwhash, sizeof(lock_pwhash), LOCK_ROUNDS) < 0) + fatal("bcrypt_pbkdf"); + success = 1; + } + freezero(passwd, pwlen); + send_status(e, success); +} + +static void +no_identities(SocketEntry *e) +{ + struct sshbuf *msg; + int r; + + if ((msg = sshbuf_new()) == NULL) + fatal_f("sshbuf_new failed"); + if ((r = sshbuf_put_u8(msg, SSH2_AGENT_IDENTITIES_ANSWER)) != 0 || + (r = sshbuf_put_u32(msg, 0)) != 0 || + (r = sshbuf_put_stringb(e->output, msg)) != 0) + fatal_fr(r, "compose"); + sshbuf_free(msg); +} + +/* Add an identity to idlist; takes ownership of 'key' and 'comment' */ +static void +add_p11_identity(struct sshkey *key, char *comment, const char *provider, + time_t death, int confirm, struct dest_constraint *dest_constraints, + size_t ndest_constraints) +{ + Identity *id; + + if (lookup_identity(key) != NULL) { + sshkey_free(key); + free(comment); + return; + } + id = xcalloc(1, sizeof(Identity)); + id->key = key; + id->comment = comment; + id->provider = xstrdup(provider); + id->death = death; + id->confirm = confirm; + id->dest_constraints = dup_dest_constraints(dest_constraints, + ndest_constraints); + id->ndest_constraints = ndest_constraints; + TAILQ_INSERT_TAIL(&idtab->idlist, id, next); + idtab->nentries++; +} + +#ifdef ENABLE_PKCS11 +static void +process_add_smartcard_key(SocketEntry *e) +{ + char *provider = NULL, *pin = NULL, canonical_provider[PATH_MAX]; + char **comments = NULL; + int r, i, count = 0, success = 0, confirm = 0; + u_int seconds = 0; + time_t death = 0; + struct sshkey **keys = NULL, *k; + struct dest_constraint *dest_constraints = NULL; + size_t j, ndest_constraints = 0, ncerts = 0; + struct sshkey **certs = NULL; + int cert_only = 0; + + debug2_f("entering"); + if ((r = sshbuf_get_cstring(e->request, &provider, NULL)) != 0 || + (r = sshbuf_get_cstring(e->request, &pin, NULL)) != 0) { + error_fr(r, "parse"); + goto send; + } + if (parse_key_constraints(e->request, NULL, &death, &seconds, &confirm, + NULL, &dest_constraints, &ndest_constraints, &cert_only, + &ncerts, &certs) != 0) { + error_f("failed to parse constraints"); + goto send; + } + dump_dest_constraints(__func__, dest_constraints, ndest_constraints); + if (socket_is_remote(e) && !remote_add_provider) { + verbose("failed PKCS#11 add of \"%.100s\": remote addition of " + "providers is disabled", provider); + goto send; + } + if (realpath(provider, canonical_provider) == NULL) { + verbose("failed PKCS#11 add of \"%.100s\": realpath: %s", + provider, strerror(errno)); + goto send; + } + if (match_pattern_list(canonical_provider, allowed_providers, 0) != 1) { + verbose("refusing PKCS#11 add of \"%.100s\": " + "provider not allowed", canonical_provider); + goto send; + } + debug_f("add %.100s", canonical_provider); + if (lifetime && !death) + death = monotime() + lifetime; + + count = pkcs11_add_provider(canonical_provider, pin, &keys, &comments); + for (i = 0; i < count; i++) { + if (comments[i] == NULL || comments[i][0] == '\0') { + free(comments[i]); + comments[i] = xstrdup(canonical_provider); + } + for (j = 0; j < ncerts; j++) { + if (!sshkey_is_cert(certs[j])) + continue; + if (!sshkey_equal_public(keys[i], certs[j])) + continue; + if (pkcs11_make_cert(keys[i], certs[j], &k) != 0) + continue; + add_p11_identity(k, xstrdup(comments[i]), + canonical_provider, death, confirm, + dest_constraints, ndest_constraints); + success = 1; + } + if (!cert_only && lookup_identity(keys[i]) == NULL) { + add_p11_identity(keys[i], comments[i], + canonical_provider, death, confirm, + dest_constraints, ndest_constraints); + keys[i] = NULL; /* transferred */ + comments[i] = NULL; /* transferred */ + success = 1; + } + /* XXX update constraints for existing keys */ + sshkey_free(keys[i]); + free(comments[i]); + } +send: + free(pin); + free(provider); + free(keys); + free(comments); + free_dest_constraints(dest_constraints, ndest_constraints); + for (j = 0; j < ncerts; j++) + sshkey_free(certs[j]); + free(certs); + send_status(e, success); +} + +static void +process_remove_smartcard_key(SocketEntry *e) +{ + char *provider = NULL, *pin = NULL, canonical_provider[PATH_MAX]; + int r, success = 0; + Identity *id, *nxt; + + debug2_f("entering"); + if ((r = sshbuf_get_cstring(e->request, &provider, NULL)) != 0 || + (r = sshbuf_get_cstring(e->request, &pin, NULL)) != 0) { + error_fr(r, "parse"); + goto send; + } + free(pin); + + if (realpath(provider, canonical_provider) == NULL) { + verbose("failed PKCS#11 add of \"%.100s\": realpath: %s", + provider, strerror(errno)); + goto send; + } + + debug_f("remove %.100s", canonical_provider); + for (id = TAILQ_FIRST(&idtab->idlist); id; id = nxt) { + nxt = TAILQ_NEXT(id, next); + /* Skip file--based keys */ + if (id->provider == NULL) + continue; + if (!strcmp(canonical_provider, id->provider)) { + TAILQ_REMOVE(&idtab->idlist, id, next); + free_identity(id); + idtab->nentries--; + } + } + if (pkcs11_del_provider(canonical_provider) == 0) + success = 1; + else + error_f("pkcs11_del_provider failed"); +send: + free(provider); + send_status(e, success); +} +#endif /* ENABLE_PKCS11 */ + +static int +process_ext_session_bind(SocketEntry *e) +{ + int r, sid_match, key_match; + struct sshkey *key = NULL; + struct sshbuf *sid = NULL, *sig = NULL; + char *fp = NULL; + size_t i; + u_char fwd = 0; + + debug2_f("entering"); + e->session_bind_attempted = 1; + if ((r = sshkey_froms(e->request, &key)) != 0 || + (r = sshbuf_froms(e->request, &sid)) != 0 || + (r = sshbuf_froms(e->request, &sig)) != 0 || + (r = sshbuf_get_u8(e->request, &fwd)) != 0) { + error_fr(r, "parse"); + goto out; + } + if ((fp = sshkey_fingerprint(key, SSH_FP_HASH_DEFAULT, + SSH_FP_DEFAULT)) == NULL) + fatal_f("fingerprint failed"); + /* check signature with hostkey on session ID */ + if ((r = sshkey_verify(key, sshbuf_ptr(sig), sshbuf_len(sig), + sshbuf_ptr(sid), sshbuf_len(sid), NULL, 0, NULL)) != 0) { + error_fr(r, "sshkey_verify for %s %s", sshkey_type(key), fp); + goto out; + } + /* check whether sid/key already recorded */ + for (i = 0; i < e->nsession_ids; i++) { + if (!e->session_ids[i].forwarded) { + error_f("attempt to bind session ID to socket " + "previously bound for authentication attempt"); + r = -1; + goto out; + } + sid_match = buf_equal(sid, e->session_ids[i].sid) == 0; + key_match = sshkey_equal(key, e->session_ids[i].key); + if (sid_match && key_match) { + debug_f("session ID already recorded for %s %s", + sshkey_type(key), fp); + r = 0; + goto out; + } else if (sid_match) { + error_f("session ID recorded against different key " + "for %s %s", sshkey_type(key), fp); + r = -1; + goto out; + } + /* + * new sid with previously-seen key can happen, e.g. multiple + * connections to the same host. + */ + } + /* record new key/sid */ + if (e->nsession_ids >= AGENT_MAX_SESSION_IDS) { + error_f("too many session IDs recorded"); + goto out; + } + e->session_ids = xrecallocarray(e->session_ids, e->nsession_ids, + e->nsession_ids + 1, sizeof(*e->session_ids)); + i = e->nsession_ids++; + debug_f("recorded %s %s (slot %zu of %d)", sshkey_type(key), fp, i, + AGENT_MAX_SESSION_IDS); + e->session_ids[i].key = key; + e->session_ids[i].forwarded = fwd != 0; + key = NULL; /* transferred */ + /* can't transfer sid; it's refcounted and scoped to request's life */ + if ((e->session_ids[i].sid = sshbuf_new()) == NULL) + fatal_f("sshbuf_new"); + if ((r = sshbuf_putb(e->session_ids[i].sid, sid)) != 0) + fatal_fr(r, "sshbuf_putb session ID"); + /* success */ + r = 0; + out: + free(fp); + sshkey_free(key); + sshbuf_free(sid); + sshbuf_free(sig); + return r == 0 ? 1 : 0; +} + +static void +process_extension(SocketEntry *e) +{ + int r, success = 0; + char *name; + + debug2_f("entering"); + if ((r = sshbuf_get_cstring(e->request, &name, NULL)) != 0) { + error_fr(r, "parse"); + goto send; + } + if (strcmp(name, "session-bind@openssh.com") == 0) + success = process_ext_session_bind(e); + else + debug_f("unsupported extension \"%s\"", name); + free(name); +send: + send_status(e, success); +} +/* + * dispatch incoming message. + * returns 1 on success, 0 for incomplete messages or -1 on error. + */ +static int +process_message(u_int socknum) +{ + u_int msg_len; + u_char type; + const u_char *cp; + int r; + SocketEntry *e; + + if (socknum >= sockets_alloc) + fatal_f("sock %u >= allocated %u", socknum, sockets_alloc); + e = &sockets[socknum]; + + if (sshbuf_len(e->input) < 5) + return 0; /* Incomplete message header. */ + cp = sshbuf_ptr(e->input); + msg_len = PEEK_U32(cp); + if (msg_len > AGENT_MAX_LEN) { + debug_f("socket %u (fd=%d) message too long %u > %u", + socknum, e->fd, msg_len, AGENT_MAX_LEN); + return -1; + } + if (sshbuf_len(e->input) < msg_len + 4) + return 0; /* Incomplete message body. */ + + /* move the current input to e->request */ + sshbuf_reset(e->request); + if ((r = sshbuf_get_stringb(e->input, e->request)) != 0 || + (r = sshbuf_get_u8(e->request, &type)) != 0) { + if (r == SSH_ERR_MESSAGE_INCOMPLETE || + r == SSH_ERR_STRING_TOO_LARGE) { + error_fr(r, "parse"); + return -1; + } + fatal_fr(r, "parse"); + } + + debug_f("socket %u (fd=%d) type %d", socknum, e->fd, type); + + /* check whether agent is locked */ + if (locked && type != SSH_AGENTC_UNLOCK) { + sshbuf_reset(e->request); + switch (type) { + case SSH2_AGENTC_REQUEST_IDENTITIES: + /* send empty lists */ + no_identities(e); + break; + default: + /* send a fail message for all other request types */ + send_status(e, 0); + } + return 1; + } + + switch (type) { + case SSH_AGENTC_LOCK: + case SSH_AGENTC_UNLOCK: + process_lock_agent(e, type == SSH_AGENTC_LOCK); + break; + case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES: + process_remove_all_identities(e); /* safe for !WITH_SSH1 */ + break; + /* ssh2 */ + case SSH2_AGENTC_SIGN_REQUEST: + process_sign_request2(e); + break; + case SSH2_AGENTC_REQUEST_IDENTITIES: + process_request_identities(e); + break; + case SSH2_AGENTC_ADD_IDENTITY: + case SSH2_AGENTC_ADD_ID_CONSTRAINED: + process_add_identity(e); + break; + case SSH2_AGENTC_REMOVE_IDENTITY: + process_remove_identity(e); + break; + case SSH2_AGENTC_REMOVE_ALL_IDENTITIES: + process_remove_all_identities(e); + break; +#ifdef ENABLE_PKCS11 + case SSH_AGENTC_ADD_SMARTCARD_KEY: + case SSH_AGENTC_ADD_SMARTCARD_KEY_CONSTRAINED: + process_add_smartcard_key(e); + break; + case SSH_AGENTC_REMOVE_SMARTCARD_KEY: + process_remove_smartcard_key(e); + break; +#endif /* ENABLE_PKCS11 */ + case SSH_AGENTC_EXTENSION: + process_extension(e); + break; + default: + /* Unknown message. Respond with failure. */ + error("Unknown message %d", type); + sshbuf_reset(e->request); + send_status(e, 0); + break; + } + return 1; +} + +static void +new_socket(sock_type type, int fd) +{ + u_int i, old_alloc, new_alloc; + + debug_f("type = %s", type == AUTH_CONNECTION ? "CONNECTION" : + (type == AUTH_SOCKET ? "SOCKET" : "UNKNOWN")); + set_nonblock(fd); + + if (fd > max_fd) + max_fd = fd; + + for (i = 0; i < sockets_alloc; i++) + if (sockets[i].type == AUTH_UNUSED) { + sockets[i].fd = fd; + if ((sockets[i].input = sshbuf_new()) == NULL || + (sockets[i].output = sshbuf_new()) == NULL || + (sockets[i].request = sshbuf_new()) == NULL) + fatal_f("sshbuf_new failed"); + sockets[i].type = type; + return; + } + old_alloc = sockets_alloc; + new_alloc = sockets_alloc + 10; + sockets = xrecallocarray(sockets, old_alloc, new_alloc, + sizeof(sockets[0])); + for (i = old_alloc; i < new_alloc; i++) + sockets[i].type = AUTH_UNUSED; + sockets_alloc = new_alloc; + sockets[old_alloc].fd = fd; + if ((sockets[old_alloc].input = sshbuf_new()) == NULL || + (sockets[old_alloc].output = sshbuf_new()) == NULL || + (sockets[old_alloc].request = sshbuf_new()) == NULL) + fatal_f("sshbuf_new failed"); + sockets[old_alloc].type = type; +} + +static int +handle_socket_read(u_int socknum) +{ + struct sockaddr_un sunaddr; + socklen_t slen; + uid_t euid; + gid_t egid; + int fd; + + slen = sizeof(sunaddr); + fd = accept(sockets[socknum].fd, (struct sockaddr *)&sunaddr, &slen); + if (fd == -1) { + error("accept from AUTH_SOCKET: %s", strerror(errno)); + return -1; + } + if (getpeereid(fd, &euid, &egid) == -1) { + error("getpeereid %d failed: %s", fd, strerror(errno)); + close(fd); + return -1; + } + if ((euid != 0) && (getuid() != euid)) { + error("uid mismatch: peer euid %u != uid %u", + (u_int) euid, (u_int) getuid()); + close(fd); + return -1; + } + new_socket(AUTH_CONNECTION, fd); + return 0; +} + +static int +handle_conn_read(u_int socknum) +{ + char buf[AGENT_RBUF_LEN]; + ssize_t len; + int r; + + if ((len = read(sockets[socknum].fd, buf, sizeof(buf))) <= 0) { + if (len == -1) { + if (errno == EAGAIN || errno == EINTR) + return 0; + error_f("read error on socket %u (fd %d): %s", + socknum, sockets[socknum].fd, strerror(errno)); + } + return -1; + } + if ((r = sshbuf_put(sockets[socknum].input, buf, len)) != 0) + fatal_fr(r, "compose"); + explicit_bzero(buf, sizeof(buf)); + for (;;) { + if ((r = process_message(socknum)) == -1) + return -1; + else if (r == 0) + break; + } + return 0; +} + +static int +handle_conn_write(u_int socknum) +{ + ssize_t len; + int r; + + if (sshbuf_len(sockets[socknum].output) == 0) + return 0; /* shouldn't happen */ + if ((len = write(sockets[socknum].fd, + sshbuf_ptr(sockets[socknum].output), + sshbuf_len(sockets[socknum].output))) <= 0) { + if (len == -1) { + if (errno == EAGAIN || errno == EINTR) + return 0; + error_f("read error on socket %u (fd %d): %s", + socknum, sockets[socknum].fd, strerror(errno)); + } + return -1; + } + if ((r = sshbuf_consume(sockets[socknum].output, len)) != 0) + fatal_fr(r, "consume"); + return 0; +} + +static void +after_poll(struct pollfd *pfd, size_t npfd, u_int maxfds) +{ + size_t i; + u_int socknum, activefds = npfd; + + for (i = 0; i < npfd; i++) { + if (pfd[i].revents == 0) + continue; + /* Find sockets entry */ + for (socknum = 0; socknum < sockets_alloc; socknum++) { + if (sockets[socknum].type != AUTH_SOCKET && + sockets[socknum].type != AUTH_CONNECTION) + continue; + if (pfd[i].fd == sockets[socknum].fd) + break; + } + if (socknum >= sockets_alloc) { + error_f("no socket for fd %d", pfd[i].fd); + continue; + } + /* Process events */ + switch (sockets[socknum].type) { + case AUTH_SOCKET: + if ((pfd[i].revents & (POLLIN|POLLERR)) == 0) + break; + if (npfd > maxfds) { + debug3("out of fds (active %u >= limit %u); " + "skipping accept", activefds, maxfds); + break; + } + if (handle_socket_read(socknum) == 0) + activefds++; + break; + case AUTH_CONNECTION: + if ((pfd[i].revents & (POLLIN|POLLHUP|POLLERR)) != 0 && + handle_conn_read(socknum) != 0) + goto close_sock; + if ((pfd[i].revents & (POLLOUT|POLLHUP)) != 0 && + handle_conn_write(socknum) != 0) { + close_sock: + if (activefds == 0) + fatal("activefds == 0 at close_sock"); + close_socket(&sockets[socknum]); + activefds--; + break; + } + break; + default: + break; + } + } +} + +static int +prepare_poll(struct pollfd **pfdp, size_t *npfdp, int *timeoutp, u_int maxfds) +{ + struct pollfd *pfd = *pfdp; + size_t i, j, npfd = 0; + time_t deadline; + int r; + + /* Count active sockets */ + for (i = 0; i < sockets_alloc; i++) { + switch (sockets[i].type) { + case AUTH_SOCKET: + case AUTH_CONNECTION: + npfd++; + break; + case AUTH_UNUSED: + break; + default: + fatal("Unknown socket type %d", sockets[i].type); + break; + } + } + if (npfd != *npfdp && + (pfd = recallocarray(pfd, *npfdp, npfd, sizeof(*pfd))) == NULL) + fatal_f("recallocarray failed"); + *pfdp = pfd; + *npfdp = npfd; + + for (i = j = 0; i < sockets_alloc; i++) { + switch (sockets[i].type) { + case AUTH_SOCKET: + if (npfd > maxfds) { + debug3("out of fds (active %zu >= limit %u); " + "skipping arming listener", npfd, maxfds); + break; + } + pfd[j].fd = sockets[i].fd; + pfd[j].revents = 0; + pfd[j].events = POLLIN; + j++; + break; + case AUTH_CONNECTION: + pfd[j].fd = sockets[i].fd; + pfd[j].revents = 0; + /* + * Only prepare to read if we can handle a full-size + * input read buffer and enqueue a max size reply.. + */ + if ((r = sshbuf_check_reserve(sockets[i].input, + AGENT_RBUF_LEN)) == 0 && + (r = sshbuf_check_reserve(sockets[i].output, + AGENT_MAX_LEN)) == 0) + pfd[j].events = POLLIN; + else if (r != SSH_ERR_NO_BUFFER_SPACE) + fatal_fr(r, "reserve"); + if (sshbuf_len(sockets[i].output) > 0) + pfd[j].events |= POLLOUT; + j++; + break; + default: + break; + } + } + deadline = reaper(); + if (parent_alive_interval != 0) + deadline = (deadline == 0) ? parent_alive_interval : + MINIMUM(deadline, parent_alive_interval); + if (deadline == 0) { + *timeoutp = -1; /* INFTIM */ + } else { + if (deadline > INT_MAX / 1000) + *timeoutp = INT_MAX / 1000; + else + *timeoutp = deadline * 1000; + } + return (1); +} + +static void +cleanup_socket(void) +{ + if (cleanup_pid != 0 && getpid() != cleanup_pid) + return; + debug_f("cleanup"); + if (socket_name[0]) + unlink(socket_name); + if (socket_dir[0]) + rmdir(socket_dir); +} + +void +cleanup_exit(int i) +{ + cleanup_socket(); + _exit(i); +} + +static void +cleanup_handler(int sig) +{ + cleanup_socket(); +#ifdef ENABLE_PKCS11 + pkcs11_terminate(); +#endif + _exit(2); +} + +static void +check_parent_exists(void) +{ + /* + * If our parent has exited then getppid() will return (pid_t)1, + * so testing for that should be safe. + */ + if (parent_pid != -1 && getppid() != parent_pid) { + /* printf("Parent has died - Authentication agent exiting.\n"); */ + cleanup_socket(); + _exit(2); + } +} + +static void +usage(void) +{ + fprintf(stderr, + "usage: ssh-agent [-c | -s] [-Dd] [-a bind_address] [-E fingerprint_hash]\n" + " [-O option] [-P allowed_providers] [-t life]\n" + " ssh-agent [-a bind_address] [-E fingerprint_hash] [-O option]\n" + " [-P allowed_providers] [-t life] command [arg ...]\n" + " ssh-agent [-c | -s] -k\n"); + exit(1); +} + +int +main(int ac, char **av) +{ + int c_flag = 0, d_flag = 0, D_flag = 0, k_flag = 0, s_flag = 0; + int sock, ch, result, saved_errno; + char *shell, *format, *pidstr, *agentsocket = NULL; +#ifdef HAVE_SETRLIMIT + struct rlimit rlim; +#endif + extern int optind; + extern char *optarg; + pid_t pid; + char pidstrbuf[1 + 3 * sizeof pid]; + size_t len; + mode_t prev_mask; + int timeout = -1; /* INFTIM */ + struct pollfd *pfd = NULL; + size_t npfd = 0; + u_int maxfds; + + /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */ + sanitise_stdfd(); + + /* drop */ + (void)setegid(getgid()); + (void)setgid(getgid()); + + platform_disable_tracing(0); /* strict=no */ + +#ifdef RLIMIT_NOFILE + if (getrlimit(RLIMIT_NOFILE, &rlim) == -1) + fatal("%s: getrlimit: %s", __progname, strerror(errno)); +#endif + + __progname = ssh_get_progname(av[0]); + seed_rng(); + + while ((ch = getopt(ac, av, "cDdksE:a:O:P:t:")) != -1) { + switch (ch) { + case 'E': + fingerprint_hash = ssh_digest_alg_by_name(optarg); + if (fingerprint_hash == -1) + fatal("Invalid hash algorithm \"%s\"", optarg); + break; + case 'c': + if (s_flag) + usage(); + c_flag++; + break; + case 'k': + k_flag++; + break; + case 'O': + if (strcmp(optarg, "no-restrict-websafe") == 0) + restrict_websafe = 0; + else if (strcmp(optarg, "allow-remote-pkcs11") == 0) + remote_add_provider = 1; + else + fatal("Unknown -O option"); + break; + case 'P': + if (allowed_providers != NULL) + fatal("-P option already specified"); + allowed_providers = xstrdup(optarg); + break; + case 's': + if (c_flag) + usage(); + s_flag++; + break; + case 'd': + if (d_flag || D_flag) + usage(); + d_flag++; + break; + case 'D': + if (d_flag || D_flag) + usage(); + D_flag++; + break; + case 'a': + agentsocket = optarg; + break; + case 't': + if ((lifetime = convtime(optarg)) == -1) { + fprintf(stderr, "Invalid lifetime\n"); + usage(); + } + break; + default: + usage(); + } + } + ac -= optind; + av += optind; + + if (ac > 0 && (c_flag || k_flag || s_flag || d_flag || D_flag)) + usage(); + + if (allowed_providers == NULL) + allowed_providers = xstrdup(DEFAULT_ALLOWED_PROVIDERS); + + if (ac == 0 && !c_flag && !s_flag) { + shell = getenv("SHELL"); + if (shell != NULL && (len = strlen(shell)) > 2 && + strncmp(shell + len - 3, "csh", 3) == 0) + c_flag = 1; + } + if (k_flag) { + const char *errstr = NULL; + + pidstr = getenv(SSH_AGENTPID_ENV_NAME); + if (pidstr == NULL) { + fprintf(stderr, "%s not set, cannot kill agent\n", + SSH_AGENTPID_ENV_NAME); + exit(1); + } + pid = (int)strtonum(pidstr, 2, INT_MAX, &errstr); + if (errstr) { + fprintf(stderr, + "%s=\"%s\", which is not a good PID: %s\n", + SSH_AGENTPID_ENV_NAME, pidstr, errstr); + exit(1); + } + if (kill(pid, SIGTERM) == -1) { + perror("kill"); + exit(1); + } + format = c_flag ? "unsetenv %s;\n" : "unset %s;\n"; + printf(format, SSH_AUTHSOCKET_ENV_NAME); + printf(format, SSH_AGENTPID_ENV_NAME); + printf("echo Agent pid %ld killed;\n", (long)pid); + exit(0); + } + + /* + * Minimum file descriptors: + * stdio (3) + listener (1) + syslog (1 maybe) + connection (1) + + * a few spare for libc / stack protectors / sanitisers, etc. + */ +#define SSH_AGENT_MIN_FDS (3+1+1+1+4) + if (rlim.rlim_cur < SSH_AGENT_MIN_FDS) + fatal("%s: file descriptor rlimit %lld too low (minimum %u)", + __progname, (long long)rlim.rlim_cur, SSH_AGENT_MIN_FDS); + maxfds = rlim.rlim_cur - SSH_AGENT_MIN_FDS; + + parent_pid = getpid(); + + if (agentsocket == NULL) { + /* Create private directory for agent socket */ + mktemp_proto(socket_dir, sizeof(socket_dir)); + if (mkdtemp(socket_dir) == NULL) { + perror("mkdtemp: private socket dir"); + exit(1); + } + snprintf(socket_name, sizeof socket_name, "%s/agent.%ld", socket_dir, + (long)parent_pid); + } else { + /* Try to use specified agent socket */ + socket_dir[0] = '\0'; + strlcpy(socket_name, agentsocket, sizeof socket_name); + } + + /* + * Create socket early so it will exist before command gets run from + * the parent. + */ + prev_mask = umask(0177); + sock = unix_listener(socket_name, SSH_LISTEN_BACKLOG, 0); + if (sock < 0) { + /* XXX - unix_listener() calls error() not perror() */ + *socket_name = '\0'; /* Don't unlink any existing file */ + cleanup_exit(1); + } + umask(prev_mask); + + /* + * Fork, and have the parent execute the command, if any, or present + * the socket data. The child continues as the authentication agent. + */ + if (D_flag || d_flag) { + log_init(__progname, + d_flag ? SYSLOG_LEVEL_DEBUG3 : SYSLOG_LEVEL_INFO, + SYSLOG_FACILITY_AUTH, 1); + format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n"; + printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name, + SSH_AUTHSOCKET_ENV_NAME); + printf("echo Agent pid %ld;\n", (long)parent_pid); + fflush(stdout); + goto skip; + } + pid = fork(); + if (pid == -1) { + perror("fork"); + cleanup_exit(1); + } + if (pid != 0) { /* Parent - execute the given command. */ + close(sock); + snprintf(pidstrbuf, sizeof pidstrbuf, "%ld", (long)pid); + if (ac == 0) { + format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n"; + printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name, + SSH_AUTHSOCKET_ENV_NAME); + printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf, + SSH_AGENTPID_ENV_NAME); + printf("echo Agent pid %ld;\n", (long)pid); + exit(0); + } + if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 || + setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) { + perror("setenv"); + exit(1); + } + execvp(av[0], av); + perror(av[0]); + exit(1); + } + /* child */ + log_init(__progname, SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_AUTH, 0); + + if (setsid() == -1) { + error("setsid: %s", strerror(errno)); + cleanup_exit(1); + } + + (void)chdir("/"); + if (stdfd_devnull(1, 1, 1) == -1) + error_f("stdfd_devnull failed"); + +#ifdef HAVE_SETRLIMIT + /* deny core dumps, since memory contains unencrypted private keys */ + rlim.rlim_cur = rlim.rlim_max = 0; + if (setrlimit(RLIMIT_CORE, &rlim) == -1) { + error("setrlimit RLIMIT_CORE: %s", strerror(errno)); + cleanup_exit(1); + } +#endif + +skip: + + cleanup_pid = getpid(); + +#ifdef ENABLE_PKCS11 + pkcs11_init(0); +#endif + new_socket(AUTH_SOCKET, sock); + if (ac > 0) + parent_alive_interval = 10; + idtab_init(); + ssh_signal(SIGPIPE, SIG_IGN); + ssh_signal(SIGINT, (d_flag | D_flag) ? cleanup_handler : SIG_IGN); + ssh_signal(SIGHUP, cleanup_handler); + ssh_signal(SIGTERM, cleanup_handler); + + if (pledge("stdio rpath cpath unix id proc exec", NULL) == -1) + fatal("%s: pledge: %s", __progname, strerror(errno)); + platform_pledge_agent(); + + while (1) { + prepare_poll(&pfd, &npfd, &timeout, maxfds); + result = poll(pfd, npfd, timeout); + saved_errno = errno; + if (parent_alive_interval != 0) + check_parent_exists(); + (void) reaper(); /* remove expired keys */ + if (result == -1) { + if (saved_errno == EINTR) + continue; + fatal("poll: %s", strerror(saved_errno)); + } else if (result > 0) + after_poll(pfd, npfd, maxfds); + } + /* NOTREACHED */ +} |