|
- /* $OpenBSD: auth2-pubkey.c,v 1.119 2023/07/27 22:25:17 djm Exp $ */
- /*
- * Copyright (c) 2000 Markus Friedl. All rights reserved.
- * Copyright (c) 2010 Damien Miller. 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 <stdlib.h>
- #include <errno.h>
- #ifdef HAVE_PATHS_H
- # include <paths.h>
- #endif
- #include <pwd.h>
- #include <signal.h>
- #include <stdio.h>
- #include <stdarg.h>
- #include <string.h>
- #include <time.h>
- #include <unistd.h>
- #include <limits.h>
-
- #include "xmalloc.h"
- #include "ssh.h"
- #include "ssh2.h"
- #include "packet.h"
- #include "kex.h"
- #include "sshbuf.h"
- #include "log.h"
- #include "misc.h"
- #include "servconf.h"
- #include "compat.h"
- #include "sshkey.h"
- #include "hostfile.h"
- #include "auth.h"
- #include "pathnames.h"
- #include "uidswap.h"
- #include "auth-options.h"
- #include "canohost.h"
- #ifdef GSSAPI
- #include "ssh-gss.h"
- #endif
- #include "monitor_wrap.h"
- #include "authfile.h"
- #include "match.h"
- #include "ssherr.h"
- #include "channels.h" /* XXX for session.h */
- #include "session.h" /* XXX for child_set_env(); refactor? */
- #include "sk-api.h"
-
- /* import */
- extern ServerOptions options;
-
- static char *
- format_key(const struct sshkey *key)
- {
- char *ret, *fp = sshkey_fingerprint(key,
- options.fingerprint_hash, SSH_FP_DEFAULT);
-
- xasprintf(&ret, "%s %s", sshkey_type(key), fp);
- free(fp);
- return ret;
- }
-
- static int
- userauth_pubkey(struct ssh *ssh, const char *method)
- {
- Authctxt *authctxt = ssh->authctxt;
- struct passwd *pw = authctxt->pw;
- struct sshbuf *b = NULL;
- struct sshkey *key = NULL, *hostkey = NULL;
- char *pkalg = NULL, *userstyle = NULL, *key_s = NULL, *ca_s = NULL;
- u_char *pkblob = NULL, *sig = NULL, have_sig;
- size_t blen, slen;
- int hostbound, r, pktype;
- int req_presence = 0, req_verify = 0, authenticated = 0;
- struct sshauthopt *authopts = NULL;
- struct sshkey_sig_details *sig_details = NULL;
-
- hostbound = strcmp(method, "publickey-hostbound-v00@openssh.com") == 0;
-
- if ((r = sshpkt_get_u8(ssh, &have_sig)) != 0 ||
- (r = sshpkt_get_cstring(ssh, &pkalg, NULL)) != 0 ||
- (r = sshpkt_get_string(ssh, &pkblob, &blen)) != 0)
- fatal_fr(r, "parse %s packet", method);
-
- /* hostbound auth includes the hostkey offered at initial KEX */
- if (hostbound) {
- if ((r = sshpkt_getb_froms(ssh, &b)) != 0 ||
- (r = sshkey_fromb(b, &hostkey)) != 0)
- fatal_fr(r, "parse %s hostkey", method);
- if (ssh->kex->initial_hostkey == NULL)
- fatal_f("internal error: initial hostkey not recorded");
- if (!sshkey_equal(hostkey, ssh->kex->initial_hostkey))
- fatal_f("%s packet contained wrong host key", method);
- sshbuf_free(b);
- b = NULL;
- }
-
- if (log_level_get() >= SYSLOG_LEVEL_DEBUG2) {
- char *keystring;
- struct sshbuf *pkbuf;
-
- if ((pkbuf = sshbuf_from(pkblob, blen)) == NULL)
- fatal_f("sshbuf_from failed");
- if ((keystring = sshbuf_dtob64_string(pkbuf, 0)) == NULL)
- fatal_f("sshbuf_dtob64 failed");
- debug2_f("%s user %s %s public key %s %s",
- authctxt->valid ? "valid" : "invalid", authctxt->user,
- have_sig ? "attempting" : "querying", pkalg, keystring);
- sshbuf_free(pkbuf);
- free(keystring);
- }
-
- pktype = sshkey_type_from_name(pkalg);
- if (pktype == KEY_UNSPEC) {
- /* this is perfectly legal */
- verbose_f("unsupported public key algorithm: %s", pkalg);
- goto done;
- }
- if ((r = sshkey_from_blob(pkblob, blen, &key)) != 0) {
- error_fr(r, "parse key");
- goto done;
- }
- if (key == NULL) {
- error_f("cannot decode key: %s", pkalg);
- goto done;
- }
- if (key->type != pktype) {
- error_f("type mismatch for decoded key "
- "(received %d, expected %d)", key->type, pktype);
- goto done;
- }
- if (auth2_key_already_used(authctxt, key)) {
- logit("refusing previously-used %s key", sshkey_type(key));
- goto done;
- }
- if (match_pattern_list(pkalg, options.pubkey_accepted_algos, 0) != 1) {
- logit_f("signature algorithm %s not in "
- "PubkeyAcceptedAlgorithms", pkalg);
- goto done;
- }
- if ((r = sshkey_check_cert_sigtype(key,
- options.ca_sign_algorithms)) != 0) {
- logit_fr(r, "certificate signature algorithm %s",
- (key->cert == NULL || key->cert->signature_type == NULL) ?
- "(null)" : key->cert->signature_type);
- goto done;
- }
- if ((r = sshkey_check_rsa_length(key,
- options.required_rsa_size)) != 0) {
- logit_r(r, "refusing %s key", sshkey_type(key));
- goto done;
- }
- key_s = format_key(key);
- if (sshkey_is_cert(key))
- ca_s = format_key(key->cert->signature_key);
-
- if (have_sig) {
- debug3_f("%s have %s signature for %s%s%s",
- method, pkalg, key_s,
- ca_s == NULL ? "" : " CA ", ca_s == NULL ? "" : ca_s);
- if ((r = sshpkt_get_string(ssh, &sig, &slen)) != 0 ||
- (r = sshpkt_get_end(ssh)) != 0)
- fatal_fr(r, "parse signature packet");
- if ((b = sshbuf_new()) == NULL)
- fatal_f("sshbuf_new failed");
- if (ssh->compat & SSH_OLD_SESSIONID) {
- if ((r = sshbuf_putb(b, ssh->kex->session_id)) != 0)
- fatal_fr(r, "put old session id");
- } else {
- if ((r = sshbuf_put_stringb(b,
- ssh->kex->session_id)) != 0)
- fatal_fr(r, "put session id");
- }
- if (!authctxt->valid || authctxt->user == NULL) {
- debug2_f("disabled because of invalid user");
- goto done;
- }
- /* reconstruct packet */
- xasprintf(&userstyle, "%s%s%s", authctxt->user,
- authctxt->style ? ":" : "",
- authctxt->style ? authctxt->style : "");
- if ((r = sshbuf_put_u8(b, SSH2_MSG_USERAUTH_REQUEST)) != 0 ||
- (r = sshbuf_put_cstring(b, userstyle)) != 0 ||
- (r = sshbuf_put_cstring(b, authctxt->service)) != 0 ||
- (r = sshbuf_put_cstring(b, method)) != 0 ||
- (r = sshbuf_put_u8(b, have_sig)) != 0 ||
- (r = sshbuf_put_cstring(b, pkalg)) != 0 ||
- (r = sshbuf_put_string(b, pkblob, blen)) != 0)
- fatal_fr(r, "reconstruct %s packet", method);
- if (hostbound &&
- (r = sshkey_puts(ssh->kex->initial_hostkey, b)) != 0)
- fatal_fr(r, "reconstruct %s packet", method);
- #ifdef DEBUG_PK
- sshbuf_dump(b, stderr);
- #endif
- /* test for correct signature */
- authenticated = 0;
- if (PRIVSEP(user_key_allowed(ssh, pw, key, 1, &authopts)) &&
- PRIVSEP(sshkey_verify(key, sig, slen,
- sshbuf_ptr(b), sshbuf_len(b),
- (ssh->compat & SSH_BUG_SIGTYPE) == 0 ? pkalg : NULL,
- ssh->compat, &sig_details)) == 0) {
- authenticated = 1;
- }
- if (authenticated == 1 && sig_details != NULL) {
- auth2_record_info(authctxt, "signature count = %u",
- sig_details->sk_counter);
- debug_f("sk_counter = %u, sk_flags = 0x%02x",
- sig_details->sk_counter, sig_details->sk_flags);
- req_presence = (options.pubkey_auth_options &
- PUBKEYAUTH_TOUCH_REQUIRED) ||
- !authopts->no_require_user_presence;
- if (req_presence && (sig_details->sk_flags &
- SSH_SK_USER_PRESENCE_REQD) == 0) {
- error("public key %s signature for %s%s from "
- "%.128s port %d rejected: user presence "
- "(authenticator touch) requirement "
- "not met ", key_s,
- authctxt->valid ? "" : "invalid user ",
- authctxt->user, ssh_remote_ipaddr(ssh),
- ssh_remote_port(ssh));
- authenticated = 0;
- goto done;
- }
- req_verify = (options.pubkey_auth_options &
- PUBKEYAUTH_VERIFY_REQUIRED) ||
- authopts->require_verify;
- if (req_verify && (sig_details->sk_flags &
- SSH_SK_USER_VERIFICATION_REQD) == 0) {
- error("public key %s signature for %s%s from "
- "%.128s port %d rejected: user "
- "verification requirement not met ", key_s,
- authctxt->valid ? "" : "invalid user ",
- authctxt->user, ssh_remote_ipaddr(ssh),
- ssh_remote_port(ssh));
- authenticated = 0;
- goto done;
- }
- }
- auth2_record_key(authctxt, authenticated, key);
- } else {
- debug_f("%s test pkalg %s pkblob %s%s%s", method, pkalg, key_s,
- ca_s == NULL ? "" : " CA ", ca_s == NULL ? "" : ca_s);
-
- if ((r = sshpkt_get_end(ssh)) != 0)
- fatal_fr(r, "parse packet");
-
- if (!authctxt->valid || authctxt->user == NULL) {
- debug2_f("disabled because of invalid user");
- goto done;
- }
- /* XXX fake reply and always send PK_OK ? */
- /*
- * XXX this allows testing whether a user is allowed
- * to login: if you happen to have a valid pubkey this
- * message is sent. the message is NEVER sent at all
- * if a user is not allowed to login. is this an
- * issue? -markus
- */
- if (PRIVSEP(user_key_allowed(ssh, pw, key, 0, NULL))) {
- if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_PK_OK))
- != 0 ||
- (r = sshpkt_put_cstring(ssh, pkalg)) != 0 ||
- (r = sshpkt_put_string(ssh, pkblob, blen)) != 0 ||
- (r = sshpkt_send(ssh)) != 0 ||
- (r = ssh_packet_write_wait(ssh)) != 0)
- fatal_fr(r, "send packet");
- authctxt->postponed = 1;
- }
- }
- done:
- if (authenticated == 1 && auth_activate_options(ssh, authopts) != 0) {
- debug_f("key options inconsistent with existing");
- authenticated = 0;
- }
- debug2_f("authenticated %d pkalg %s", authenticated, pkalg);
-
- sshbuf_free(b);
- sshauthopt_free(authopts);
- sshkey_free(key);
- sshkey_free(hostkey);
- free(userstyle);
- free(pkalg);
- free(pkblob);
- free(key_s);
- free(ca_s);
- free(sig);
- sshkey_sig_details_free(sig_details);
- return authenticated;
- }
-
- static int
- match_principals_file(struct passwd *pw, char *file,
- struct sshkey_cert *cert, struct sshauthopt **authoptsp)
- {
- FILE *f;
- int success;
-
- if (authoptsp != NULL)
- *authoptsp = NULL;
-
- temporarily_use_uid(pw);
- debug("trying authorized principals file %s", file);
- if ((f = auth_openprincipals(file, pw, options.strict_modes)) == NULL) {
- restore_uid();
- return 0;
- }
- success = auth_process_principals(f, file, cert, authoptsp);
- fclose(f);
- restore_uid();
- return success;
- }
-
- /*
- * Checks whether principal is allowed in output of command.
- * returns 1 if the principal is allowed or 0 otherwise.
- */
- static int
- match_principals_command(struct passwd *user_pw, const struct sshkey *key,
- const char *conn_id, const char *rdomain, struct sshauthopt **authoptsp)
- {
- struct passwd *runas_pw = NULL;
- const struct sshkey_cert *cert = key->cert;
- FILE *f = NULL;
- int r, ok, found_principal = 0;
- int i, ac = 0, uid_swapped = 0;
- pid_t pid;
- char *tmp, *username = NULL, *command = NULL, **av = NULL;
- char *ca_fp = NULL, *key_fp = NULL, *catext = NULL, *keytext = NULL;
- char serial_s[32], uidstr[32];
- void (*osigchld)(int);
-
- if (authoptsp != NULL)
- *authoptsp = NULL;
- if (options.authorized_principals_command == NULL)
- return 0;
- if (options.authorized_principals_command_user == NULL) {
- error("No user for AuthorizedPrincipalsCommand specified, "
- "skipping");
- return 0;
- }
-
- /*
- * NB. all returns later this function should go via "out" to
- * ensure the original SIGCHLD handler is restored properly.
- */
- osigchld = ssh_signal(SIGCHLD, SIG_DFL);
-
- /* Prepare and verify the user for the command */
- username = percent_expand(options.authorized_principals_command_user,
- "u", user_pw->pw_name, (char *)NULL);
- runas_pw = getpwnam(username);
- if (runas_pw == NULL) {
- error("AuthorizedPrincipalsCommandUser \"%s\" not found: %s",
- username, strerror(errno));
- goto out;
- }
-
- /* Turn the command into an argument vector */
- if (argv_split(options.authorized_principals_command,
- &ac, &av, 0) != 0) {
- error("AuthorizedPrincipalsCommand \"%s\" contains "
- "invalid quotes", options.authorized_principals_command);
- goto out;
- }
- if (ac == 0) {
- error("AuthorizedPrincipalsCommand \"%s\" yielded no arguments",
- options.authorized_principals_command);
- goto out;
- }
- if ((ca_fp = sshkey_fingerprint(cert->signature_key,
- options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) {
- error_f("sshkey_fingerprint failed");
- goto out;
- }
- if ((key_fp = sshkey_fingerprint(key,
- options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) {
- error_f("sshkey_fingerprint failed");
- goto out;
- }
- if ((r = sshkey_to_base64(cert->signature_key, &catext)) != 0) {
- error_fr(r, "sshkey_to_base64 failed");
- goto out;
- }
- if ((r = sshkey_to_base64(key, &keytext)) != 0) {
- error_fr(r, "sshkey_to_base64 failed");
- goto out;
- }
- snprintf(serial_s, sizeof(serial_s), "%llu",
- (unsigned long long)cert->serial);
- snprintf(uidstr, sizeof(uidstr), "%llu",
- (unsigned long long)user_pw->pw_uid);
- for (i = 1; i < ac; i++) {
- tmp = percent_expand(av[i],
- "C", conn_id,
- "D", rdomain,
- "U", uidstr,
- "u", user_pw->pw_name,
- "h", user_pw->pw_dir,
- "t", sshkey_ssh_name(key),
- "T", sshkey_ssh_name(cert->signature_key),
- "f", key_fp,
- "F", ca_fp,
- "k", keytext,
- "K", catext,
- "i", cert->key_id,
- "s", serial_s,
- (char *)NULL);
- if (tmp == NULL)
- fatal_f("percent_expand failed");
- free(av[i]);
- av[i] = tmp;
- }
- /* Prepare a printable command for logs, etc. */
- command = argv_assemble(ac, av);
-
- if ((pid = subprocess("AuthorizedPrincipalsCommand", command,
- ac, av, &f,
- SSH_SUBPROCESS_STDOUT_CAPTURE|SSH_SUBPROCESS_STDERR_DISCARD,
- runas_pw, temporarily_use_uid, restore_uid)) == 0)
- goto out;
-
- uid_swapped = 1;
- temporarily_use_uid(runas_pw);
-
- ok = auth_process_principals(f, "(command)", cert, authoptsp);
-
- fclose(f);
- f = NULL;
-
- if (exited_cleanly(pid, "AuthorizedPrincipalsCommand", command, 0) != 0)
- goto out;
-
- /* Read completed successfully */
- found_principal = ok;
- out:
- if (f != NULL)
- fclose(f);
- ssh_signal(SIGCHLD, osigchld);
- for (i = 0; i < ac; i++)
- free(av[i]);
- free(av);
- if (uid_swapped)
- restore_uid();
- free(command);
- free(username);
- free(ca_fp);
- free(key_fp);
- free(catext);
- free(keytext);
- return found_principal;
- }
-
- /* Authenticate a certificate key against TrustedUserCAKeys */
- static int
- user_cert_trusted_ca(struct passwd *pw, struct sshkey *key,
- const char *remote_ip, const char *remote_host,
- const char *conn_id, const char *rdomain, struct sshauthopt **authoptsp)
- {
- char *ca_fp, *principals_file = NULL;
- const char *reason;
- struct sshauthopt *principals_opts = NULL, *cert_opts = NULL;
- struct sshauthopt *final_opts = NULL;
- int r, ret = 0, found_principal = 0, use_authorized_principals;
-
- if (authoptsp != NULL)
- *authoptsp = NULL;
-
- if (!sshkey_is_cert(key) || options.trusted_user_ca_keys == NULL)
- return 0;
-
- if ((ca_fp = sshkey_fingerprint(key->cert->signature_key,
- options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL)
- return 0;
-
- if ((r = sshkey_in_file(key->cert->signature_key,
- options.trusted_user_ca_keys, 1, 0)) != 0) {
- debug2_fr(r, "CA %s %s is not listed in %s",
- sshkey_type(key->cert->signature_key), ca_fp,
- options.trusted_user_ca_keys);
- goto out;
- }
- /*
- * If AuthorizedPrincipals is in use, then compare the certificate
- * principals against the names in that file rather than matching
- * against the username.
- */
- if ((principals_file = authorized_principals_file(pw)) != NULL) {
- if (match_principals_file(pw, principals_file,
- key->cert, &principals_opts))
- found_principal = 1;
- }
- /* Try querying command if specified */
- if (!found_principal && match_principals_command(pw, key,
- conn_id, rdomain, &principals_opts))
- found_principal = 1;
- /* If principals file or command is specified, then require a match */
- use_authorized_principals = principals_file != NULL ||
- options.authorized_principals_command != NULL;
- if (!found_principal && use_authorized_principals) {
- reason = "Certificate does not contain an authorized principal";
- goto fail_reason;
- }
- if (use_authorized_principals && principals_opts == NULL)
- fatal_f("internal error: missing principals_opts");
- if (sshkey_cert_check_authority_now(key, 0, 1, 0,
- use_authorized_principals ? NULL : pw->pw_name, &reason) != 0)
- goto fail_reason;
-
- /* Check authority from options in key and from principals file/cmd */
- if ((cert_opts = sshauthopt_from_cert(key)) == NULL) {
- reason = "Invalid certificate options";
- goto fail_reason;
- }
- if (auth_authorise_keyopts(pw, cert_opts, 0,
- remote_ip, remote_host, "cert") != 0) {
- reason = "Refused by certificate options";
- goto fail_reason;
- }
- if (principals_opts == NULL) {
- final_opts = cert_opts;
- cert_opts = NULL;
- } else {
- if (auth_authorise_keyopts(pw, principals_opts, 0,
- remote_ip, remote_host, "principals") != 0) {
- reason = "Refused by certificate principals options";
- goto fail_reason;
- }
- if ((final_opts = sshauthopt_merge(principals_opts,
- cert_opts, &reason)) == NULL) {
- fail_reason:
- error("%s", reason);
- auth_debug_add("%s", reason);
- goto out;
- }
- }
-
- /* Success */
- verbose("Accepted certificate ID \"%s\" (serial %llu) signed by "
- "%s CA %s via %s", key->cert->key_id,
- (unsigned long long)key->cert->serial,
- sshkey_type(key->cert->signature_key), ca_fp,
- options.trusted_user_ca_keys);
- if (authoptsp != NULL) {
- *authoptsp = final_opts;
- final_opts = NULL;
- }
- ret = 1;
- out:
- sshauthopt_free(principals_opts);
- sshauthopt_free(cert_opts);
- sshauthopt_free(final_opts);
- free(principals_file);
- free(ca_fp);
- return ret;
- }
-
- /*
- * Checks whether key is allowed in file.
- * returns 1 if the key is allowed or 0 otherwise.
- */
- static int
- user_key_allowed2(struct passwd *pw, struct sshkey *key,
- char *file, const char *remote_ip, const char *remote_host,
- struct sshauthopt **authoptsp)
- {
- FILE *f;
- int found_key = 0;
-
- if (authoptsp != NULL)
- *authoptsp = NULL;
-
- /* Temporarily use the user's uid. */
- temporarily_use_uid(pw);
-
- debug("trying public key file %s", file);
- if ((f = auth_openkeyfile(file, pw, options.strict_modes)) != NULL) {
- found_key = auth_check_authkeys_file(pw, f, file,
- key, remote_ip, remote_host, authoptsp);
- fclose(f);
- }
-
- restore_uid();
- return found_key;
- }
-
- /*
- * Checks whether key is allowed in output of command.
- * returns 1 if the key is allowed or 0 otherwise.
- */
- static int
- user_key_command_allowed2(struct passwd *user_pw, struct sshkey *key,
- const char *remote_ip, const char *remote_host,
- const char *conn_id, const char *rdomain, struct sshauthopt **authoptsp)
- {
- struct passwd *runas_pw = NULL;
- FILE *f = NULL;
- int r, ok, found_key = 0;
- int i, uid_swapped = 0, ac = 0;
- pid_t pid;
- char *username = NULL, *key_fp = NULL, *keytext = NULL;
- char uidstr[32], *tmp, *command = NULL, **av = NULL;
- void (*osigchld)(int);
-
- if (authoptsp != NULL)
- *authoptsp = NULL;
- if (options.authorized_keys_command == NULL)
- return 0;
- if (options.authorized_keys_command_user == NULL) {
- error("No user for AuthorizedKeysCommand specified, skipping");
- return 0;
- }
-
- /*
- * NB. all returns later this function should go via "out" to
- * ensure the original SIGCHLD handler is restored properly.
- */
- osigchld = ssh_signal(SIGCHLD, SIG_DFL);
-
- /* Prepare and verify the user for the command */
- username = percent_expand(options.authorized_keys_command_user,
- "u", user_pw->pw_name, (char *)NULL);
- runas_pw = getpwnam(username);
- if (runas_pw == NULL) {
- error("AuthorizedKeysCommandUser \"%s\" not found: %s",
- username, strerror(errno));
- goto out;
- }
-
- /* Prepare AuthorizedKeysCommand */
- if ((key_fp = sshkey_fingerprint(key, options.fingerprint_hash,
- SSH_FP_DEFAULT)) == NULL) {
- error_f("sshkey_fingerprint failed");
- goto out;
- }
- if ((r = sshkey_to_base64(key, &keytext)) != 0) {
- error_fr(r, "sshkey_to_base64 failed");
- goto out;
- }
-
- /* Turn the command into an argument vector */
- if (argv_split(options.authorized_keys_command, &ac, &av, 0) != 0) {
- error("AuthorizedKeysCommand \"%s\" contains invalid quotes",
- options.authorized_keys_command);
- goto out;
- }
- if (ac == 0) {
- error("AuthorizedKeysCommand \"%s\" yielded no arguments",
- options.authorized_keys_command);
- goto out;
- }
- snprintf(uidstr, sizeof(uidstr), "%llu",
- (unsigned long long)user_pw->pw_uid);
- for (i = 1; i < ac; i++) {
- tmp = percent_expand(av[i],
- "C", conn_id,
- "D", rdomain,
- "U", uidstr,
- "u", user_pw->pw_name,
- "h", user_pw->pw_dir,
- "t", sshkey_ssh_name(key),
- "f", key_fp,
- "k", keytext,
- (char *)NULL);
- if (tmp == NULL)
- fatal_f("percent_expand failed");
- free(av[i]);
- av[i] = tmp;
- }
- /* Prepare a printable command for logs, etc. */
- command = argv_assemble(ac, av);
-
- /*
- * If AuthorizedKeysCommand was run without arguments
- * then fall back to the old behaviour of passing the
- * target username as a single argument.
- */
- if (ac == 1) {
- av = xreallocarray(av, ac + 2, sizeof(*av));
- av[1] = xstrdup(user_pw->pw_name);
- av[2] = NULL;
- /* Fix up command too, since it is used in log messages */
- free(command);
- xasprintf(&command, "%s %s", av[0], av[1]);
- }
-
- if ((pid = subprocess("AuthorizedKeysCommand", command,
- ac, av, &f,
- SSH_SUBPROCESS_STDOUT_CAPTURE|SSH_SUBPROCESS_STDERR_DISCARD,
- runas_pw, temporarily_use_uid, restore_uid)) == 0)
- goto out;
-
- uid_swapped = 1;
- temporarily_use_uid(runas_pw);
-
- ok = auth_check_authkeys_file(user_pw, f,
- options.authorized_keys_command, key, remote_ip,
- remote_host, authoptsp);
-
- fclose(f);
- f = NULL;
-
- if (exited_cleanly(pid, "AuthorizedKeysCommand", command, 0) != 0)
- goto out;
-
- /* Read completed successfully */
- found_key = ok;
- out:
- if (f != NULL)
- fclose(f);
- ssh_signal(SIGCHLD, osigchld);
- for (i = 0; i < ac; i++)
- free(av[i]);
- free(av);
- if (uid_swapped)
- restore_uid();
- free(command);
- free(username);
- free(key_fp);
- free(keytext);
- return found_key;
- }
-
- /*
- * Check whether key authenticates and authorises the user.
- */
- int
- user_key_allowed(struct ssh *ssh, struct passwd *pw, struct sshkey *key,
- int auth_attempt, struct sshauthopt **authoptsp)
- {
- u_int success = 0, i;
- char *file, *conn_id;
- struct sshauthopt *opts = NULL;
- const char *rdomain, *remote_ip, *remote_host;
-
- if (authoptsp != NULL)
- *authoptsp = NULL;
-
- if (auth_key_is_revoked(key))
- return 0;
- if (sshkey_is_cert(key) &&
- auth_key_is_revoked(key->cert->signature_key))
- return 0;
-
- if ((rdomain = ssh_packet_rdomain_in(ssh)) == NULL)
- rdomain = "";
- remote_ip = ssh_remote_ipaddr(ssh);
- remote_host = auth_get_canonical_hostname(ssh, options.use_dns);
- xasprintf(&conn_id, "%s %d %s %d",
- ssh_local_ipaddr(ssh), ssh_local_port(ssh),
- remote_ip, ssh_remote_port(ssh));
-
- for (i = 0; !success && i < options.num_authkeys_files; i++) {
- if (strcasecmp(options.authorized_keys_files[i], "none") == 0)
- continue;
- file = expand_authorized_keys(
- options.authorized_keys_files[i], pw);
- success = user_key_allowed2(pw, key, file,
- remote_ip, remote_host, &opts);
- free(file);
- if (!success) {
- sshauthopt_free(opts);
- opts = NULL;
- }
- }
- if (success)
- goto out;
-
- if ((success = user_cert_trusted_ca(pw, key, remote_ip, remote_host,
- conn_id, rdomain, &opts)) != 0)
- goto out;
- sshauthopt_free(opts);
- opts = NULL;
-
- if ((success = user_key_command_allowed2(pw, key, remote_ip,
- remote_host, conn_id, rdomain, &opts)) != 0)
- goto out;
- sshauthopt_free(opts);
- opts = NULL;
-
- out:
- free(conn_id);
- if (success && authoptsp != NULL) {
- *authoptsp = opts;
- opts = NULL;
- }
- sshauthopt_free(opts);
- return success;
- }
-
- Authmethod method_pubkey = {
- "publickey",
- "publickey-hostbound-v00@openssh.com",
- userauth_pubkey,
- &options.pubkey_authentication
- };
|