| /* $OpenBSD: sshd.c,v 1.540 2019/11/13 11:25:11 dtucker Exp $ */ |
| /* |
| * Author: Tatu Ylonen <ylo@cs.hut.fi> |
| * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland |
| * All rights reserved |
| * This program is the ssh daemon. It listens for connections from clients, |
| * and performs authentication, executes use commands or shell, and forwards |
| * information to/from the application to the user client over an encrypted |
| * connection. This can also handle forwarding of X11, TCP/IP, and |
| * authentication agent connections. |
| * |
| * 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". |
| * |
| * SSH2 implementation: |
| * Privilege Separation: |
| * |
| * Copyright (c) 2000, 2001, 2002 Markus Friedl. All rights reserved. |
| * Copyright (c) 2002 Niels Provos. 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/ioctl.h> |
| #include <sys/socket.h> |
| #ifdef HAVE_SYS_STAT_H |
| # include <sys/stat.h> |
| #endif |
| #ifdef HAVE_SYS_TIME_H |
| # include <sys/time.h> |
| #endif |
| #include "openbsd-compat/sys-tree.h" |
| #include "openbsd-compat/sys-queue.h" |
| #include <sys/wait.h> |
| |
| #include <errno.h> |
| #include <fcntl.h> |
| #include <netdb.h> |
| #ifdef HAVE_PATHS_H |
| #include <paths.h> |
| #endif |
| #include <grp.h> |
| #include <pwd.h> |
| #include <signal.h> |
| #include <stdarg.h> |
| #include <stdio.h> |
| #include <stdlib.h> |
| #include <string.h> |
| #include <unistd.h> |
| #include <limits.h> |
| |
| #ifdef WITH_OPENSSL |
| #include <openssl/dh.h> |
| #include <openssl/bn.h> |
| #include <openssl/rand.h> |
| #include "openbsd-compat/openssl-compat.h" |
| #endif |
| |
| #ifdef HAVE_SECUREWARE |
| #include <sys/security.h> |
| #include <prot.h> |
| #endif |
| |
| #include "xmalloc.h" |
| #include "ssh.h" |
| #include "ssh2.h" |
| #include "sshpty.h" |
| #include "packet.h" |
| #include "log.h" |
| #include "sshbuf.h" |
| #include "misc.h" |
| #include "match.h" |
| #include "servconf.h" |
| #include "uidswap.h" |
| #include "compat.h" |
| #include "cipher.h" |
| #include "digest.h" |
| #include "sshkey.h" |
| #include "kex.h" |
| #include "myproposal.h" |
| #include "authfile.h" |
| #include "pathnames.h" |
| #include "atomicio.h" |
| #include "canohost.h" |
| #include "hostfile.h" |
| #include "auth.h" |
| #include "authfd.h" |
| #include "msg.h" |
| #include "dispatch.h" |
| #include "channels.h" |
| #include "session.h" |
| #include "monitor.h" |
| #ifdef GSSAPI |
| #include "ssh-gss.h" |
| #endif |
| #include "monitor_wrap.h" |
| #include "ssh-sandbox.h" |
| #include "auth-options.h" |
| #include "version.h" |
| #include "ssherr.h" |
| |
| /* Re-exec fds */ |
| #define REEXEC_DEVCRYPTO_RESERVED_FD (STDERR_FILENO + 1) |
| #define REEXEC_STARTUP_PIPE_FD (STDERR_FILENO + 2) |
| #define REEXEC_CONFIG_PASS_FD (STDERR_FILENO + 3) |
| #define REEXEC_MIN_FREE_FD (STDERR_FILENO + 4) |
| |
| extern char *__progname; |
| |
| /* Server configuration options. */ |
| ServerOptions options; |
| |
| /* Name of the server configuration file. */ |
| char *config_file_name = _PATH_SERVER_CONFIG_FILE; |
| |
| /* |
| * Debug mode flag. This can be set on the command line. If debug |
| * mode is enabled, extra debugging output will be sent to the system |
| * log, the daemon will not go to background, and will exit after processing |
| * the first connection. |
| */ |
| int debug_flag = 0; |
| |
| /* |
| * Indicating that the daemon should only test the configuration and keys. |
| * If test_flag > 1 ("-T" flag), then sshd will also dump the effective |
| * configuration, optionally using connection information provided by the |
| * "-C" flag. |
| */ |
| static int test_flag = 0; |
| |
| /* Flag indicating that the daemon is being started from inetd. */ |
| static int inetd_flag = 0; |
| |
| /* Flag indicating that sshd should not detach and become a daemon. */ |
| static int no_daemon_flag = 0; |
| |
| /* debug goes to stderr unless inetd_flag is set */ |
| static int log_stderr = 0; |
| |
| /* Saved arguments to main(). */ |
| static char **saved_argv; |
| static int saved_argc; |
| |
| /* re-exec */ |
| static int rexeced_flag = 0; |
| static int rexec_flag = 1; |
| static int rexec_argc = 0; |
| static char **rexec_argv; |
| |
| /* |
| * The sockets that the server is listening; this is used in the SIGHUP |
| * signal handler. |
| */ |
| #define MAX_LISTEN_SOCKS 16 |
| static int listen_socks[MAX_LISTEN_SOCKS]; |
| static int num_listen_socks = 0; |
| |
| /* Daemon's agent connection */ |
| int auth_sock = -1; |
| static int have_agent = 0; |
| |
| /* |
| * Any really sensitive data in the application is contained in this |
| * structure. The idea is that this structure could be locked into memory so |
| * that the pages do not get written into swap. However, there are some |
| * problems. The private key contains BIGNUMs, and we do not (in principle) |
| * have access to the internals of them, and locking just the structure is |
| * not very useful. Currently, memory locking is not implemented. |
| */ |
| struct { |
| struct sshkey **host_keys; /* all private host keys */ |
| struct sshkey **host_pubkeys; /* all public host keys */ |
| struct sshkey **host_certificates; /* all public host certificates */ |
| int have_ssh2_key; |
| } sensitive_data; |
| |
| /* This is set to true when a signal is received. */ |
| static volatile sig_atomic_t received_sighup = 0; |
| static volatile sig_atomic_t received_sigterm = 0; |
| |
| /* session identifier, used by RSA-auth */ |
| u_char session_id[16]; |
| |
| /* same for ssh2 */ |
| u_char *session_id2 = NULL; |
| u_int session_id2_len = 0; |
| |
| /* record remote hostname or ip */ |
| u_int utmp_len = HOST_NAME_MAX+1; |
| |
| /* |
| * startup_pipes/flags are used for tracking children of the listening sshd |
| * process early in their lifespans. This tracking is needed for three things: |
| * |
| * 1) Implementing the MaxStartups limit of concurrent unauthenticated |
| * connections. |
| * 2) Avoiding a race condition for SIGHUP processing, where child processes |
| * may have listen_socks open that could collide with main listener process |
| * after it restarts. |
| * 3) Ensuring that rexec'd sshd processes have received their initial state |
| * from the parent listen process before handling SIGHUP. |
| * |
| * Child processes signal that they have completed closure of the listen_socks |
| * and (if applicable) received their rexec state by sending a char over their |
| * sock. Child processes signal that authentication has completed by closing |
| * the sock (or by exiting). |
| */ |
| static int *startup_pipes = NULL; |
| static int *startup_flags = NULL; /* Indicates child closed listener */ |
| static int startup_pipe = -1; /* in child */ |
| |
| /* variables used for privilege separation */ |
| int use_privsep = -1; |
| struct monitor *pmonitor = NULL; |
| int privsep_is_preauth = 1; |
| static int privsep_chroot = 1; |
| |
| /* global connection state and authentication contexts */ |
| Authctxt *the_authctxt = NULL; |
| struct ssh *the_active_state; |
| |
| /* global key/cert auth options. XXX move to permanent ssh->authctxt? */ |
| struct sshauthopt *auth_opts = NULL; |
| |
| /* sshd_config buffer */ |
| struct sshbuf *cfg; |
| |
| /* message to be displayed after login */ |
| struct sshbuf *loginmsg; |
| |
| /* Unprivileged user */ |
| struct passwd *privsep_pw = NULL; |
| |
| /* Prototypes for various functions defined later in this file. */ |
| void destroy_sensitive_data(void); |
| void demote_sensitive_data(void); |
| static void do_ssh2_kex(struct ssh *); |
| |
| /* |
| * Close all listening sockets |
| */ |
| static void |
| close_listen_socks(void) |
| { |
| int i; |
| |
| for (i = 0; i < num_listen_socks; i++) |
| close(listen_socks[i]); |
| num_listen_socks = -1; |
| } |
| |
| static void |
| close_startup_pipes(void) |
| { |
| int i; |
| |
| if (startup_pipes) |
| for (i = 0; i < options.max_startups; i++) |
| if (startup_pipes[i] != -1) |
| close(startup_pipes[i]); |
| } |
| |
| /* |
| * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP; |
| * the effect is to reread the configuration file (and to regenerate |
| * the server key). |
| */ |
| |
| /*ARGSUSED*/ |
| static void |
| sighup_handler(int sig) |
| { |
| received_sighup = 1; |
| } |
| |
| /* |
| * Called from the main program after receiving SIGHUP. |
| * Restarts the server. |
| */ |
| static void |
| sighup_restart(void) |
| { |
| logit("Received SIGHUP; restarting."); |
| if (options.pid_file != NULL) |
| unlink(options.pid_file); |
| platform_pre_restart(); |
| close_listen_socks(); |
| close_startup_pipes(); |
| alarm(0); /* alarm timer persists across exec */ |
| signal(SIGHUP, SIG_IGN); /* will be restored after exec */ |
| execv(saved_argv[0], saved_argv); |
| logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0], |
| strerror(errno)); |
| exit(1); |
| } |
| |
| /* |
| * Generic signal handler for terminating signals in the master daemon. |
| */ |
| /*ARGSUSED*/ |
| static void |
| sigterm_handler(int sig) |
| { |
| received_sigterm = sig; |
| } |
| |
| /* |
| * SIGCHLD handler. This is called whenever a child dies. This will then |
| * reap any zombies left by exited children. |
| */ |
| /*ARGSUSED*/ |
| static void |
| main_sigchld_handler(int sig) |
| { |
| int save_errno = errno; |
| pid_t pid; |
| int status; |
| |
| while ((pid = waitpid(-1, &status, WNOHANG)) > 0 || |
| (pid == -1 && errno == EINTR)) |
| ; |
| errno = save_errno; |
| } |
| |
| /* |
| * Signal handler for the alarm after the login grace period has expired. |
| */ |
| /*ARGSUSED*/ |
| static void |
| grace_alarm_handler(int sig) |
| { |
| if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0) |
| kill(pmonitor->m_pid, SIGALRM); |
| |
| /* |
| * Try to kill any processes that we have spawned, E.g. authorized |
| * keys command helpers. |
| */ |
| if (getpgid(0) == getpid()) { |
| signal(SIGTERM, SIG_IGN); |
| kill(0, SIGTERM); |
| } |
| |
| /* XXX pre-format ipaddr/port so we don't need to access active_state */ |
| /* Log error and exit. */ |
| sigdie("Timeout before authentication for %s port %d", |
| ssh_remote_ipaddr(the_active_state), |
| ssh_remote_port(the_active_state)); |
| } |
| |
| /* Destroy the host and server keys. They will no longer be needed. */ |
| void |
| destroy_sensitive_data(void) |
| { |
| u_int i; |
| |
| for (i = 0; i < options.num_host_key_files; i++) { |
| if (sensitive_data.host_keys[i]) { |
| sshkey_free(sensitive_data.host_keys[i]); |
| sensitive_data.host_keys[i] = NULL; |
| } |
| if (sensitive_data.host_certificates[i]) { |
| sshkey_free(sensitive_data.host_certificates[i]); |
| sensitive_data.host_certificates[i] = NULL; |
| } |
| } |
| } |
| |
| /* Demote private to public keys for network child */ |
| void |
| demote_sensitive_data(void) |
| { |
| struct sshkey *tmp; |
| u_int i; |
| int r; |
| |
| for (i = 0; i < options.num_host_key_files; i++) { |
| if (sensitive_data.host_keys[i]) { |
| if ((r = sshkey_from_private( |
| sensitive_data.host_keys[i], &tmp)) != 0) |
| fatal("could not demote host %s key: %s", |
| sshkey_type(sensitive_data.host_keys[i]), |
| ssh_err(r)); |
| sshkey_free(sensitive_data.host_keys[i]); |
| sensitive_data.host_keys[i] = tmp; |
| } |
| /* Certs do not need demotion */ |
| } |
| } |
| |
| static void |
| reseed_prngs(void) |
| { |
| u_int32_t rnd[256]; |
| |
| #ifdef WITH_OPENSSL |
| RAND_poll(); |
| #endif |
| arc4random_stir(); /* noop on recent arc4random() implementations */ |
| arc4random_buf(rnd, sizeof(rnd)); /* let arc4random notice PID change */ |
| |
| #ifdef WITH_OPENSSL |
| RAND_seed(rnd, sizeof(rnd)); |
| /* give libcrypto a chance to notice the PID change */ |
| if ((RAND_bytes((u_char *)rnd, 1)) != 1) |
| fatal("%s: RAND_bytes failed", __func__); |
| #endif |
| |
| explicit_bzero(rnd, sizeof(rnd)); |
| } |
| |
| static void |
| privsep_preauth_child(void) |
| { |
| gid_t gidset[1]; |
| |
| /* Enable challenge-response authentication for privilege separation */ |
| privsep_challenge_enable(); |
| |
| #ifdef GSSAPI |
| /* Cache supported mechanism OIDs for later use */ |
| ssh_gssapi_prepare_supported_oids(); |
| #endif |
| |
| reseed_prngs(); |
| |
| /* Demote the private keys to public keys. */ |
| demote_sensitive_data(); |
| |
| /* Demote the child */ |
| if (privsep_chroot) { |
| /* Change our root directory */ |
| if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1) |
| fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR, |
| strerror(errno)); |
| if (chdir("/") == -1) |
| fatal("chdir(\"/\"): %s", strerror(errno)); |
| |
| /* Drop our privileges */ |
| debug3("privsep user:group %u:%u", (u_int)privsep_pw->pw_uid, |
| (u_int)privsep_pw->pw_gid); |
| gidset[0] = privsep_pw->pw_gid; |
| if (setgroups(1, gidset) == -1) |
| fatal("setgroups: %.100s", strerror(errno)); |
| permanently_set_uid(privsep_pw); |
| } |
| } |
| |
| static int |
| privsep_preauth(struct ssh *ssh) |
| { |
| int status, r; |
| pid_t pid; |
| struct ssh_sandbox *box = NULL; |
| |
| /* Set up unprivileged child process to deal with network data */ |
| pmonitor = monitor_init(); |
| /* Store a pointer to the kex for later rekeying */ |
| pmonitor->m_pkex = &ssh->kex; |
| |
| if (use_privsep == PRIVSEP_ON) |
| box = ssh_sandbox_init(pmonitor); |
| pid = fork(); |
| if (pid == -1) { |
| fatal("fork of unprivileged child failed"); |
| } else if (pid != 0) { |
| debug2("Network child is on pid %ld", (long)pid); |
| |
| pmonitor->m_pid = pid; |
| if (have_agent) { |
| r = ssh_get_authentication_socket(&auth_sock); |
| if (r != 0) { |
| error("Could not get agent socket: %s", |
| ssh_err(r)); |
| have_agent = 0; |
| } |
| } |
| if (box != NULL) |
| ssh_sandbox_parent_preauth(box, pid); |
| monitor_child_preauth(ssh, pmonitor); |
| |
| /* Wait for the child's exit status */ |
| while (waitpid(pid, &status, 0) == -1) { |
| if (errno == EINTR) |
| continue; |
| pmonitor->m_pid = -1; |
| fatal("%s: waitpid: %s", __func__, strerror(errno)); |
| } |
| privsep_is_preauth = 0; |
| pmonitor->m_pid = -1; |
| if (WIFEXITED(status)) { |
| if (WEXITSTATUS(status) != 0) |
| fatal("%s: preauth child exited with status %d", |
| __func__, WEXITSTATUS(status)); |
| } else if (WIFSIGNALED(status)) |
| fatal("%s: preauth child terminated by signal %d", |
| __func__, WTERMSIG(status)); |
| if (box != NULL) |
| ssh_sandbox_parent_finish(box); |
| return 1; |
| } else { |
| /* child */ |
| close(pmonitor->m_sendfd); |
| close(pmonitor->m_log_recvfd); |
| |
| /* Arrange for logging to be sent to the monitor */ |
| set_log_handler(mm_log_handler, pmonitor); |
| |
| privsep_preauth_child(); |
| setproctitle("%s", "[net]"); |
| if (box != NULL) |
| ssh_sandbox_child(box); |
| |
| return 0; |
| } |
| } |
| |
| static void |
| privsep_postauth(struct ssh *ssh, Authctxt *authctxt) |
| { |
| #ifdef DISABLE_FD_PASSING |
| if (1) { |
| #else |
| if (authctxt->pw->pw_uid == 0) { |
| #endif |
| /* File descriptor passing is broken or root login */ |
| use_privsep = 0; |
| goto skip; |
| } |
| |
| /* New socket pair */ |
| monitor_reinit(pmonitor); |
| |
| pmonitor->m_pid = fork(); |
| if (pmonitor->m_pid == -1) |
| fatal("fork of unprivileged child failed"); |
| else if (pmonitor->m_pid != 0) { |
| verbose("User child is on pid %ld", (long)pmonitor->m_pid); |
| sshbuf_reset(loginmsg); |
| monitor_clear_keystate(ssh, pmonitor); |
| monitor_child_postauth(ssh, pmonitor); |
| |
| /* NEVERREACHED */ |
| exit(0); |
| } |
| |
| /* child */ |
| |
| close(pmonitor->m_sendfd); |
| pmonitor->m_sendfd = -1; |
| |
| /* Demote the private keys to public keys. */ |
| demote_sensitive_data(); |
| |
| reseed_prngs(); |
| |
| /* Drop privileges */ |
| do_setusercontext(authctxt->pw); |
| |
| skip: |
| /* It is safe now to apply the key state */ |
| monitor_apply_keystate(ssh, pmonitor); |
| |
| /* |
| * Tell the packet layer that authentication was successful, since |
| * this information is not part of the key state. |
| */ |
| ssh_packet_set_authenticated(ssh); |
| } |
| |
| static void |
| append_hostkey_type(struct sshbuf *b, const char *s) |
| { |
| int r; |
| |
| if (match_pattern_list(s, options.hostkeyalgorithms, 0) != 1) { |
| debug3("%s: %s key not permitted by HostkeyAlgorithms", |
| __func__, s); |
| return; |
| } |
| if ((r = sshbuf_putf(b, "%s%s", sshbuf_len(b) > 0 ? "," : "", s)) != 0) |
| fatal("%s: sshbuf_putf: %s", __func__, ssh_err(r)); |
| } |
| |
| static char * |
| list_hostkey_types(void) |
| { |
| struct sshbuf *b; |
| struct sshkey *key; |
| char *ret; |
| u_int i; |
| |
| if ((b = sshbuf_new()) == NULL) |
| fatal("%s: sshbuf_new failed", __func__); |
| for (i = 0; i < options.num_host_key_files; i++) { |
| key = sensitive_data.host_keys[i]; |
| if (key == NULL) |
| key = sensitive_data.host_pubkeys[i]; |
| if (key == NULL) |
| continue; |
| switch (key->type) { |
| case KEY_RSA: |
| /* for RSA we also support SHA2 signatures */ |
| append_hostkey_type(b, "rsa-sha2-512"); |
| append_hostkey_type(b, "rsa-sha2-256"); |
| /* FALLTHROUGH */ |
| case KEY_DSA: |
| case KEY_ECDSA: |
| case KEY_ED25519: |
| case KEY_XMSS: |
| append_hostkey_type(b, sshkey_ssh_name(key)); |
| break; |
| } |
| /* If the private key has a cert peer, then list that too */ |
| key = sensitive_data.host_certificates[i]; |
| if (key == NULL) |
| continue; |
| switch (key->type) { |
| case KEY_RSA_CERT: |
| /* for RSA we also support SHA2 signatures */ |
| append_hostkey_type(b, |
| "rsa-sha2-512-cert-v01@openssh.com"); |
| append_hostkey_type(b, |
| "rsa-sha2-256-cert-v01@openssh.com"); |
| /* FALLTHROUGH */ |
| case KEY_DSA_CERT: |
| case KEY_ECDSA_CERT: |
| case KEY_ED25519_CERT: |
| case KEY_XMSS_CERT: |
| append_hostkey_type(b, sshkey_ssh_name(key)); |
| break; |
| } |
| } |
| if ((ret = sshbuf_dup_string(b)) == NULL) |
| fatal("%s: sshbuf_dup_string failed", __func__); |
| sshbuf_free(b); |
| debug("%s: %s", __func__, ret); |
| return ret; |
| } |
| |
| static struct sshkey * |
| get_hostkey_by_type(int type, int nid, int need_private, struct ssh *ssh) |
| { |
| u_int i; |
| struct sshkey *key; |
| |
| for (i = 0; i < options.num_host_key_files; i++) { |
| switch (type) { |
| case KEY_RSA_CERT: |
| case KEY_DSA_CERT: |
| case KEY_ECDSA_CERT: |
| case KEY_ED25519_CERT: |
| case KEY_XMSS_CERT: |
| key = sensitive_data.host_certificates[i]; |
| break; |
| default: |
| key = sensitive_data.host_keys[i]; |
| if (key == NULL && !need_private) |
| key = sensitive_data.host_pubkeys[i]; |
| break; |
| } |
| if (key != NULL && key->type == type && |
| (key->type != KEY_ECDSA || key->ecdsa_nid == nid)) |
| return need_private ? |
| sensitive_data.host_keys[i] : key; |
| } |
| return NULL; |
| } |
| |
| struct sshkey * |
| get_hostkey_public_by_type(int type, int nid, struct ssh *ssh) |
| { |
| return get_hostkey_by_type(type, nid, 0, ssh); |
| } |
| |
| struct sshkey * |
| get_hostkey_private_by_type(int type, int nid, struct ssh *ssh) |
| { |
| return get_hostkey_by_type(type, nid, 1, ssh); |
| } |
| |
| struct sshkey * |
| get_hostkey_by_index(int ind) |
| { |
| if (ind < 0 || (u_int)ind >= options.num_host_key_files) |
| return (NULL); |
| return (sensitive_data.host_keys[ind]); |
| } |
| |
| struct sshkey * |
| get_hostkey_public_by_index(int ind, struct ssh *ssh) |
| { |
| if (ind < 0 || (u_int)ind >= options.num_host_key_files) |
| return (NULL); |
| return (sensitive_data.host_pubkeys[ind]); |
| } |
| |
| int |
| get_hostkey_index(struct sshkey *key, int compare, struct ssh *ssh) |
| { |
| u_int i; |
| |
| for (i = 0; i < options.num_host_key_files; i++) { |
| if (sshkey_is_cert(key)) { |
| if (key == sensitive_data.host_certificates[i] || |
| (compare && sensitive_data.host_certificates[i] && |
| sshkey_equal(key, |
| sensitive_data.host_certificates[i]))) |
| return (i); |
| } else { |
| if (key == sensitive_data.host_keys[i] || |
| (compare && sensitive_data.host_keys[i] && |
| sshkey_equal(key, sensitive_data.host_keys[i]))) |
| return (i); |
| if (key == sensitive_data.host_pubkeys[i] || |
| (compare && sensitive_data.host_pubkeys[i] && |
| sshkey_equal(key, sensitive_data.host_pubkeys[i]))) |
| return (i); |
| } |
| } |
| return (-1); |
| } |
| |
| /* Inform the client of all hostkeys */ |
| static void |
| notify_hostkeys(struct ssh *ssh) |
| { |
| struct sshbuf *buf; |
| struct sshkey *key; |
| u_int i, nkeys; |
| int r; |
| char *fp; |
| |
| /* Some clients cannot cope with the hostkeys message, skip those. */ |
| if (ssh->compat & SSH_BUG_HOSTKEYS) |
| return; |
| |
| if ((buf = sshbuf_new()) == NULL) |
| fatal("%s: sshbuf_new", __func__); |
| for (i = nkeys = 0; i < options.num_host_key_files; i++) { |
| key = get_hostkey_public_by_index(i, ssh); |
| if (key == NULL || key->type == KEY_UNSPEC || |
| sshkey_is_cert(key)) |
| continue; |
| fp = sshkey_fingerprint(key, options.fingerprint_hash, |
| SSH_FP_DEFAULT); |
| debug3("%s: key %d: %s %s", __func__, i, |
| sshkey_ssh_name(key), fp); |
| free(fp); |
| if (nkeys == 0) { |
| /* |
| * Start building the request when we find the |
| * first usable key. |
| */ |
| if ((r = sshpkt_start(ssh, SSH2_MSG_GLOBAL_REQUEST)) != 0 || |
| (r = sshpkt_put_cstring(ssh, "hostkeys-00@openssh.com")) != 0 || |
| (r = sshpkt_put_u8(ssh, 0)) != 0) /* want reply */ |
| sshpkt_fatal(ssh, r, "%s: start request", __func__); |
| } |
| /* Append the key to the request */ |
| sshbuf_reset(buf); |
| if ((r = sshkey_putb(key, buf)) != 0) |
| fatal("%s: couldn't put hostkey %d: %s", |
| __func__, i, ssh_err(r)); |
| if ((r = sshpkt_put_stringb(ssh, buf)) != 0) |
| sshpkt_fatal(ssh, r, "%s: append key", __func__); |
| nkeys++; |
| } |
| debug3("%s: sent %u hostkeys", __func__, nkeys); |
| if (nkeys == 0) |
| fatal("%s: no hostkeys", __func__); |
| if ((r = sshpkt_send(ssh)) != 0) |
| sshpkt_fatal(ssh, r, "%s: send", __func__); |
| sshbuf_free(buf); |
| } |
| |
| /* |
| * returns 1 if connection should be dropped, 0 otherwise. |
| * dropping starts at connection #max_startups_begin with a probability |
| * of (max_startups_rate/100). the probability increases linearly until |
| * all connections are dropped for startups > max_startups |
| */ |
| static int |
| drop_connection(int startups) |
| { |
| int p, r; |
| |
| if (startups < options.max_startups_begin) |
| return 0; |
| if (startups >= options.max_startups) |
| return 1; |
| if (options.max_startups_rate == 100) |
| return 1; |
| |
| p = 100 - options.max_startups_rate; |
| p *= startups - options.max_startups_begin; |
| p /= options.max_startups - options.max_startups_begin; |
| p += options.max_startups_rate; |
| r = arc4random_uniform(100); |
| |
| debug("drop_connection: p %d, r %d", p, r); |
| return (r < p) ? 1 : 0; |
| } |
| |
| static void |
| usage(void) |
| { |
| fprintf(stderr, "%s, %s\n", |
| SSH_RELEASE, |
| #ifdef WITH_OPENSSL |
| OpenSSL_version(OPENSSL_VERSION) |
| #else |
| "without OpenSSL" |
| #endif |
| ); |
| fprintf(stderr, |
| "usage: sshd [-46DdeiqTt] [-C connection_spec] [-c host_cert_file]\n" |
| " [-E log_file] [-f config_file] [-g login_grace_time]\n" |
| " [-h host_key_file] [-o option] [-p port] [-u len]\n" |
| ); |
| exit(1); |
| } |
| |
| static void |
| send_rexec_state(int fd, struct sshbuf *conf) |
| { |
| struct sshbuf *m; |
| int r; |
| |
| debug3("%s: entering fd = %d config len %zu", __func__, fd, |
| sshbuf_len(conf)); |
| |
| /* |
| * Protocol from reexec master to child: |
| * string configuration |
| * string rngseed (only if OpenSSL is not self-seeded) |
| */ |
| if ((m = sshbuf_new()) == NULL) |
| fatal("%s: sshbuf_new failed", __func__); |
| if ((r = sshbuf_put_stringb(m, conf)) != 0) |
| fatal("%s: buffer error: %s", __func__, ssh_err(r)); |
| |
| #if defined(WITH_OPENSSL) && !defined(OPENSSL_PRNG_ONLY) |
| rexec_send_rng_seed(m); |
| #endif |
| |
| if (ssh_msg_send(fd, 0, m) == -1) |
| fatal("%s: ssh_msg_send failed", __func__); |
| |
| sshbuf_free(m); |
| |
| debug3("%s: done", __func__); |
| } |
| |
| static void |
| recv_rexec_state(int fd, struct sshbuf *conf) |
| { |
| struct sshbuf *m; |
| u_char *cp, ver; |
| size_t len; |
| int r; |
| |
| debug3("%s: entering fd = %d", __func__, fd); |
| |
| if ((m = sshbuf_new()) == NULL) |
| fatal("%s: sshbuf_new failed", __func__); |
| if (ssh_msg_recv(fd, m) == -1) |
| fatal("%s: ssh_msg_recv failed", __func__); |
| if ((r = sshbuf_get_u8(m, &ver)) != 0) |
| fatal("%s: buffer error: %s", __func__, ssh_err(r)); |
| if (ver != 0) |
| fatal("%s: rexec version mismatch", __func__); |
| if ((r = sshbuf_get_string(m, &cp, &len)) != 0) |
| fatal("%s: buffer error: %s", __func__, ssh_err(r)); |
| if (conf != NULL && (r = sshbuf_put(conf, cp, len))) |
| fatal("%s: buffer error: %s", __func__, ssh_err(r)); |
| #if defined(WITH_OPENSSL) && !defined(OPENSSL_PRNG_ONLY) |
| rexec_recv_rng_seed(m); |
| #endif |
| |
| free(cp); |
| sshbuf_free(m); |
| |
| debug3("%s: done", __func__); |
| } |
| |
| /* Accept a connection from inetd */ |
| static void |
| server_accept_inetd(int *sock_in, int *sock_out) |
| { |
| int fd; |
| |
| if (rexeced_flag) { |
| close(REEXEC_CONFIG_PASS_FD); |
| *sock_in = *sock_out = dup(STDIN_FILENO); |
| } else { |
| *sock_in = dup(STDIN_FILENO); |
| *sock_out = dup(STDOUT_FILENO); |
| } |
| /* |
| * We intentionally do not close the descriptors 0, 1, and 2 |
| * as our code for setting the descriptors won't work if |
| * ttyfd happens to be one of those. |
| */ |
| if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) { |
| dup2(fd, STDIN_FILENO); |
| dup2(fd, STDOUT_FILENO); |
| if (!log_stderr) |
| dup2(fd, STDERR_FILENO); |
| if (fd > (log_stderr ? STDERR_FILENO : STDOUT_FILENO)) |
| close(fd); |
| } |
| debug("inetd sockets after dupping: %d, %d", *sock_in, *sock_out); |
| } |
| |
| /* |
| * Listen for TCP connections |
| */ |
| static void |
| listen_on_addrs(struct listenaddr *la) |
| { |
| int ret, listen_sock; |
| struct addrinfo *ai; |
| char ntop[NI_MAXHOST], strport[NI_MAXSERV]; |
| |
| for (ai = la->addrs; ai; ai = ai->ai_next) { |
| if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6) |
| continue; |
| if (num_listen_socks >= MAX_LISTEN_SOCKS) |
| fatal("Too many listen sockets. " |
| "Enlarge MAX_LISTEN_SOCKS"); |
| if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen, |
| ntop, sizeof(ntop), strport, sizeof(strport), |
| NI_NUMERICHOST|NI_NUMERICSERV)) != 0) { |
| error("getnameinfo failed: %.100s", |
| ssh_gai_strerror(ret)); |
| continue; |
| } |
| /* Create socket for listening. */ |
| listen_sock = socket(ai->ai_family, ai->ai_socktype, |
| ai->ai_protocol); |
| if (listen_sock == -1) { |
| /* kernel may not support ipv6 */ |
| verbose("socket: %.100s", strerror(errno)); |
| continue; |
| } |
| if (set_nonblock(listen_sock) == -1) { |
| close(listen_sock); |
| continue; |
| } |
| if (fcntl(listen_sock, F_SETFD, FD_CLOEXEC) == -1) { |
| verbose("socket: CLOEXEC: %s", strerror(errno)); |
| close(listen_sock); |
| continue; |
| } |
| /* Socket options */ |
| set_reuseaddr(listen_sock); |
| if (la->rdomain != NULL && |
| set_rdomain(listen_sock, la->rdomain) == -1) { |
| close(listen_sock); |
| continue; |
| } |
| |
| /* Only communicate in IPv6 over AF_INET6 sockets. */ |
| if (ai->ai_family == AF_INET6) |
| sock_set_v6only(listen_sock); |
| |
| debug("Bind to port %s on %s.", strport, ntop); |
| |
| /* Bind the socket to the desired port. */ |
| if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) == -1) { |
| error("Bind to port %s on %s failed: %.200s.", |
| strport, ntop, strerror(errno)); |
| close(listen_sock); |
| continue; |
| } |
| listen_socks[num_listen_socks] = listen_sock; |
| num_listen_socks++; |
| |
| /* Start listening on the port. */ |
| if (listen(listen_sock, SSH_LISTEN_BACKLOG) == -1) |
| fatal("listen on [%s]:%s: %.100s", |
| ntop, strport, strerror(errno)); |
| logit("Server listening on %s port %s%s%s.", |
| ntop, strport, |
| la->rdomain == NULL ? "" : " rdomain ", |
| la->rdomain == NULL ? "" : la->rdomain); |
| } |
| } |
| |
| static void |
| server_listen(void) |
| { |
| u_int i; |
| |
| for (i = 0; i < options.num_listen_addrs; i++) { |
| listen_on_addrs(&options.listen_addrs[i]); |
| freeaddrinfo(options.listen_addrs[i].addrs); |
| free(options.listen_addrs[i].rdomain); |
| memset(&options.listen_addrs[i], 0, |
| sizeof(options.listen_addrs[i])); |
| } |
| free(options.listen_addrs); |
| options.listen_addrs = NULL; |
| options.num_listen_addrs = 0; |
| |
| if (!num_listen_socks) |
| fatal("Cannot bind any address."); |
| } |
| |
| /* |
| * The main TCP accept loop. Note that, for the non-debug case, returns |
| * from this function are in a forked subprocess. |
| */ |
| static void |
| server_accept_loop(int *sock_in, int *sock_out, int *newsock, int *config_s) |
| { |
| fd_set *fdset; |
| int i, j, ret, maxfd; |
| int startups = 0, listening = 0, lameduck = 0; |
| int startup_p[2] = { -1 , -1 }; |
| char c = 0; |
| struct sockaddr_storage from; |
| socklen_t fromlen; |
| pid_t pid; |
| u_char rnd[256]; |
| |
| /* setup fd set for accept */ |
| fdset = NULL; |
| maxfd = 0; |
| for (i = 0; i < num_listen_socks; i++) |
| if (listen_socks[i] > maxfd) |
| maxfd = listen_socks[i]; |
| /* pipes connected to unauthenticated childs */ |
| startup_pipes = xcalloc(options.max_startups, sizeof(int)); |
| startup_flags = xcalloc(options.max_startups, sizeof(int)); |
| for (i = 0; i < options.max_startups; i++) |
| startup_pipes[i] = -1; |
| |
| /* |
| * Stay listening for connections until the system crashes or |
| * the daemon is killed with a signal. |
| */ |
| for (;;) { |
| if (received_sighup) { |
| if (!lameduck) { |
| debug("Received SIGHUP; waiting for children"); |
| close_listen_socks(); |
| lameduck = 1; |
| } |
| if (listening <= 0) |
| sighup_restart(); |
| } |
| free(fdset); |
| fdset = xcalloc(howmany(maxfd + 1, NFDBITS), |
| sizeof(fd_mask)); |
| |
| for (i = 0; i < num_listen_socks; i++) |
| FD_SET(listen_socks[i], fdset); |
| for (i = 0; i < options.max_startups; i++) |
| if (startup_pipes[i] != -1) |
| FD_SET(startup_pipes[i], fdset); |
| |
| /* Wait in select until there is a connection. */ |
| ret = select(maxfd+1, fdset, NULL, NULL, NULL); |
| if (ret == -1 && errno != EINTR) |
| error("select: %.100s", strerror(errno)); |
| if (received_sigterm) { |
| logit("Received signal %d; terminating.", |
| (int) received_sigterm); |
| close_listen_socks(); |
| if (options.pid_file != NULL) |
| unlink(options.pid_file); |
| exit(received_sigterm == SIGTERM ? 0 : 255); |
| } |
| if (ret == -1) |
| continue; |
| |
| for (i = 0; i < options.max_startups; i++) { |
| if (startup_pipes[i] == -1 || |
| !FD_ISSET(startup_pipes[i], fdset)) |
| continue; |
| switch (read(startup_pipes[i], &c, sizeof(c))) { |
| case -1: |
| if (errno == EINTR || errno == EAGAIN) |
| continue; |
| if (errno != EPIPE) { |
| error("%s: startup pipe %d (fd=%d): " |
| "read %s", __func__, i, |
| startup_pipes[i], strerror(errno)); |
| } |
| /* FALLTHROUGH */ |
| case 0: |
| /* child exited or completed auth */ |
| close(startup_pipes[i]); |
| startup_pipes[i] = -1; |
| startups--; |
| if (startup_flags[i]) |
| listening--; |
| break; |
| case 1: |
| /* child has finished preliminaries */ |
| if (startup_flags[i]) { |
| listening--; |
| startup_flags[i] = 0; |
| } |
| break; |
| } |
| } |
| for (i = 0; i < num_listen_socks; i++) { |
| if (!FD_ISSET(listen_socks[i], fdset)) |
| continue; |
| fromlen = sizeof(from); |
| *newsock = accept(listen_socks[i], |
| (struct sockaddr *)&from, &fromlen); |
| if (*newsock == -1) { |
| if (errno != EINTR && errno != EWOULDBLOCK && |
| errno != ECONNABORTED && errno != EAGAIN) |
| error("accept: %.100s", |
| strerror(errno)); |
| if (errno == EMFILE || errno == ENFILE) |
| usleep(100 * 1000); |
| continue; |
| } |
| if (unset_nonblock(*newsock) == -1) { |
| close(*newsock); |
| continue; |
| } |
| if (drop_connection(startups) == 1) { |
| char *laddr = get_local_ipaddr(*newsock); |
| char *raddr = get_peer_ipaddr(*newsock); |
| char msg[] = "Exceeded MaxStartups\r\n"; |
| |
| verbose("drop connection #%d from [%s]:%d " |
| "on [%s]:%d past MaxStartups", startups, |
| raddr, get_peer_port(*newsock), |
| laddr, get_local_port(*newsock)); |
| free(laddr); |
| free(raddr); |
| /* best-effort notification to client */ |
| (void)write(*newsock, msg, strlen(msg)); |
| close(*newsock); |
| continue; |
| } |
| if (pipe(startup_p) == -1) { |
| close(*newsock); |
| continue; |
| } |
| |
| if (rexec_flag && socketpair(AF_UNIX, |
| SOCK_STREAM, 0, config_s) == -1) { |
| error("reexec socketpair: %s", |
| strerror(errno)); |
| close(*newsock); |
| close(startup_p[0]); |
| close(startup_p[1]); |
| continue; |
| } |
| |
| for (j = 0; j < options.max_startups; j++) |
| if (startup_pipes[j] == -1) { |
| startup_pipes[j] = startup_p[0]; |
| if (maxfd < startup_p[0]) |
| maxfd = startup_p[0]; |
| startups++; |
| startup_flags[j] = 1; |
| break; |
| } |
| |
| /* |
| * Got connection. Fork a child to handle it, unless |
| * we are in debugging mode. |
| */ |
| if (debug_flag) { |
| /* |
| * In debugging mode. Close the listening |
| * socket, and start processing the |
| * connection without forking. |
| */ |
| debug("Server will not fork when running in debugging mode."); |
| close_listen_socks(); |
| *sock_in = *newsock; |
| *sock_out = *newsock; |
| close(startup_p[0]); |
| close(startup_p[1]); |
| startup_pipe = -1; |
| pid = getpid(); |
| if (rexec_flag) { |
| send_rexec_state(config_s[0], cfg); |
| close(config_s[0]); |
| } |
| return; |
| } |
| |
| /* |
| * Normal production daemon. Fork, and have |
| * the child process the connection. The |
| * parent continues listening. |
| */ |
| platform_pre_fork(); |
| listening++; |
| if ((pid = fork()) == 0) { |
| /* |
| * Child. Close the listening and |
| * max_startup sockets. Start using |
| * the accepted socket. Reinitialize |
| * logging (since our pid has changed). |
| * We return from this function to handle |
| * the connection. |
| */ |
| platform_post_fork_child(); |
| startup_pipe = startup_p[1]; |
| close_startup_pipes(); |
| close_listen_socks(); |
| *sock_in = *newsock; |
| *sock_out = *newsock; |
| log_init(__progname, |
| options.log_level, |
| options.log_facility, |
| log_stderr); |
| if (rexec_flag) |
| close(config_s[0]); |
| else { |
| /* |
| * Signal parent that the preliminaries |
| * for this child are complete. For the |
| * re-exec case, this happens after the |
| * child has received the rexec state |
| * from the server. |
| */ |
| (void)atomicio(vwrite, startup_pipe, |
| "\0", 1); |
| } |
| return; |
| } |
| |
| /* Parent. Stay in the loop. */ |
| platform_post_fork_parent(pid); |
| if (pid == -1) |
| error("fork: %.100s", strerror(errno)); |
| else |
| debug("Forked child %ld.", (long)pid); |
| |
| close(startup_p[1]); |
| |
| if (rexec_flag) { |
| send_rexec_state(config_s[0], cfg); |
| close(config_s[0]); |
| close(config_s[1]); |
| } |
| close(*newsock); |
| |
| /* |
| * Ensure that our random state differs |
| * from that of the child |
| */ |
| arc4random_stir(); |
| arc4random_buf(rnd, sizeof(rnd)); |
| #ifdef WITH_OPENSSL |
| RAND_seed(rnd, sizeof(rnd)); |
| if ((RAND_bytes((u_char *)rnd, 1)) != 1) |
| fatal("%s: RAND_bytes failed", __func__); |
| #endif |
| explicit_bzero(rnd, sizeof(rnd)); |
| } |
| } |
| } |
| |
| /* |
| * If IP options are supported, make sure there are none (log and |
| * return an error if any are found). Basically we are worried about |
| * source routing; it can be used to pretend you are somebody |
| * (ip-address) you are not. That itself may be "almost acceptable" |
| * under certain circumstances, but rhosts authentication is useless |
| * if source routing is accepted. Notice also that if we just dropped |
| * source routing here, the other side could use IP spoofing to do |
| * rest of the interaction and could still bypass security. So we |
| * exit here if we detect any IP options. |
| */ |
| static void |
| check_ip_options(struct ssh *ssh) |
| { |
| #ifdef IP_OPTIONS |
| int sock_in = ssh_packet_get_connection_in(ssh); |
| struct sockaddr_storage from; |
| u_char opts[200]; |
| socklen_t i, option_size = sizeof(opts), fromlen = sizeof(from); |
| char text[sizeof(opts) * 3 + 1]; |
| |
| memset(&from, 0, sizeof(from)); |
| if (getpeername(sock_in, (struct sockaddr *)&from, |
| &fromlen) == -1) |
| return; |
| if (from.ss_family != AF_INET) |
| return; |
| /* XXX IPv6 options? */ |
| |
| if (getsockopt(sock_in, IPPROTO_IP, IP_OPTIONS, opts, |
| &option_size) >= 0 && option_size != 0) { |
| text[0] = '\0'; |
| for (i = 0; i < option_size; i++) |
| snprintf(text + i*3, sizeof(text) - i*3, |
| " %2.2x", opts[i]); |
| fatal("Connection from %.100s port %d with IP opts: %.800s", |
| ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), text); |
| } |
| return; |
| #endif /* IP_OPTIONS */ |
| } |
| |
| /* Set the routing domain for this process */ |
| static void |
| set_process_rdomain(struct ssh *ssh, const char *name) |
| { |
| #if defined(HAVE_SYS_SET_PROCESS_RDOMAIN) |
| if (name == NULL) |
| return; /* default */ |
| |
| if (strcmp(name, "%D") == 0) { |
| /* "expands" to routing domain of connection */ |
| if ((name = ssh_packet_rdomain_in(ssh)) == NULL) |
| return; |
| } |
| /* NB. We don't pass 'ssh' to sys_set_process_rdomain() */ |
| return sys_set_process_rdomain(name); |
| #elif defined(__OpenBSD__) |
| int rtable, ortable = getrtable(); |
| const char *errstr; |
| |
| if (name == NULL) |
| return; /* default */ |
| |
| if (strcmp(name, "%D") == 0) { |
| /* "expands" to routing domain of connection */ |
| if ((name = ssh_packet_rdomain_in(ssh)) == NULL) |
| return; |
| } |
| |
| rtable = (int)strtonum(name, 0, 255, &errstr); |
| if (errstr != NULL) /* Shouldn't happen */ |
| fatal("Invalid routing domain \"%s\": %s", name, errstr); |
| if (rtable != ortable && setrtable(rtable) != 0) |
| fatal("Unable to set routing domain %d: %s", |
| rtable, strerror(errno)); |
| debug("%s: set routing domain %d (was %d)", __func__, rtable, ortable); |
| #else /* defined(__OpenBSD__) */ |
| fatal("Unable to set routing domain: not supported in this platform"); |
| #endif |
| } |
| |
| static void |
| accumulate_host_timing_secret(struct sshbuf *server_cfg, |
| struct sshkey *key) |
| { |
| static struct ssh_digest_ctx *ctx; |
| u_char *hash; |
| size_t len; |
| struct sshbuf *buf; |
| int r; |
| |
| if (ctx == NULL && (ctx = ssh_digest_start(SSH_DIGEST_SHA512)) == NULL) |
| fatal("%s: ssh_digest_start", __func__); |
| if (key == NULL) { /* finalize */ |
| /* add server config in case we are using agent for host keys */ |
| if (ssh_digest_update(ctx, sshbuf_ptr(server_cfg), |
| sshbuf_len(server_cfg)) != 0) |
| fatal("%s: ssh_digest_update", __func__); |
| len = ssh_digest_bytes(SSH_DIGEST_SHA512); |
| hash = xmalloc(len); |
| if (ssh_digest_final(ctx, hash, len) != 0) |
| fatal("%s: ssh_digest_final", __func__); |
| options.timing_secret = PEEK_U64(hash); |
| freezero(hash, len); |
| ssh_digest_free(ctx); |
| ctx = NULL; |
| return; |
| } |
| if ((buf = sshbuf_new()) == NULL) |
| fatal("%s could not allocate buffer", __func__); |
| if ((r = sshkey_private_serialize(key, buf)) != 0) |
| fatal("sshkey_private_serialize: %s", ssh_err(r)); |
| if (ssh_digest_update(ctx, sshbuf_ptr(buf), sshbuf_len(buf)) != 0) |
| fatal("%s: ssh_digest_update", __func__); |
| sshbuf_reset(buf); |
| sshbuf_free(buf); |
| } |
| |
| /* |
| * Main program for the daemon. |
| */ |
| int |
| main(int ac, char **av) |
| { |
| struct ssh *ssh = NULL; |
| extern char *optarg; |
| extern int optind; |
| int r, opt, on = 1, already_daemon, remote_port; |
| int sock_in = -1, sock_out = -1, newsock = -1; |
| const char *remote_ip, *rdomain; |
| char *fp, *line, *laddr, *logfile = NULL; |
| int config_s[2] = { -1 , -1 }; |
| u_int i, j; |
| u_int64_t ibytes, obytes; |
| mode_t new_umask; |
| struct sshkey *key; |
| struct sshkey *pubkey; |
| int keytype; |
| Authctxt *authctxt; |
| struct connection_info *connection_info = NULL; |
| |
| #ifdef HAVE_SECUREWARE |
| (void)set_auth_parameters(ac, av); |
| #endif |
| __progname = ssh_get_progname(av[0]); |
| |
| /* Save argv. Duplicate so setproctitle emulation doesn't clobber it */ |
| saved_argc = ac; |
| rexec_argc = ac; |
| saved_argv = xcalloc(ac + 1, sizeof(*saved_argv)); |
| for (i = 0; (int)i < ac; i++) |
| saved_argv[i] = xstrdup(av[i]); |
| saved_argv[i] = NULL; |
| |
| #ifndef HAVE_SETPROCTITLE |
| /* Prepare for later setproctitle emulation */ |
| compat_init_setproctitle(ac, av); |
| av = saved_argv; |
| #endif |
| |
| if (geteuid() == 0 && setgroups(0, NULL) == -1) |
| debug("setgroups(): %.200s", strerror(errno)); |
| |
| /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */ |
| sanitise_stdfd(); |
| |
| seed_rng(); |
| |
| /* Initialize configuration options to their default values. */ |
| initialize_server_options(&options); |
| |
| /* Parse command-line arguments. */ |
| while ((opt = getopt(ac, av, |
| "C:E:b:c:f:g:h:k:o:p:u:46DQRTdeiqrt")) != -1) { |
| switch (opt) { |
| case '4': |
| options.address_family = AF_INET; |
| break; |
| case '6': |
| options.address_family = AF_INET6; |
| break; |
| case 'f': |
| config_file_name = optarg; |
| break; |
| case 'c': |
| servconf_add_hostcert("[command-line]", 0, |
| &options, optarg); |
| break; |
| case 'd': |
| if (debug_flag == 0) { |
| debug_flag = 1; |
| options.log_level = SYSLOG_LEVEL_DEBUG1; |
| } else if (options.log_level < SYSLOG_LEVEL_DEBUG3) |
| options.log_level++; |
| break; |
| case 'D': |
| no_daemon_flag = 1; |
| break; |
| case 'E': |
| logfile = optarg; |
| /* FALLTHROUGH */ |
| case 'e': |
| log_stderr = 1; |
| break; |
| case 'i': |
| inetd_flag = 1; |
| break; |
| case 'r': |
| rexec_flag = 0; |
| break; |
| case 'R': |
| rexeced_flag = 1; |
| inetd_flag = 1; |
| break; |
| case 'Q': |
| /* ignored */ |
| break; |
| case 'q': |
| options.log_level = SYSLOG_LEVEL_QUIET; |
| break; |
| case 'b': |
| /* protocol 1, ignored */ |
| break; |
| case 'p': |
| options.ports_from_cmdline = 1; |
| if (options.num_ports >= MAX_PORTS) { |
| fprintf(stderr, "too many ports.\n"); |
| exit(1); |
| } |
| options.ports[options.num_ports++] = a2port(optarg); |
| if (options.ports[options.num_ports-1] <= 0) { |
| fprintf(stderr, "Bad port number.\n"); |
| exit(1); |
| } |
| break; |
| case 'g': |
| if ((options.login_grace_time = convtime(optarg)) == -1) { |
| fprintf(stderr, "Invalid login grace time.\n"); |
| exit(1); |
| } |
| break; |
| case 'k': |
| /* protocol 1, ignored */ |
| break; |
| case 'h': |
| servconf_add_hostkey("[command-line]", 0, |
| &options, optarg, 1); |
| break; |
| case 't': |
| test_flag = 1; |
| break; |
| case 'T': |
| test_flag = 2; |
| break; |
| case 'C': |
| connection_info = get_connection_info(ssh, 0, 0); |
| if (parse_server_match_testspec(connection_info, |
| optarg) == -1) |
| exit(1); |
| break; |
| case 'u': |
| utmp_len = (u_int)strtonum(optarg, 0, HOST_NAME_MAX+1+1, NULL); |
| if (utmp_len > HOST_NAME_MAX+1) { |
| fprintf(stderr, "Invalid utmp length.\n"); |
| exit(1); |
| } |
| break; |
| case 'o': |
| line = xstrdup(optarg); |
| if (process_server_config_line(&options, line, |
| "command-line", 0, NULL, NULL) != 0) |
| exit(1); |
| free(line); |
| break; |
| case '?': |
| default: |
| usage(); |
| break; |
| } |
| } |
| if (rexeced_flag || inetd_flag) |
| rexec_flag = 0; |
| if (!test_flag && rexec_flag && !path_absolute(av[0])) |
| fatal("sshd re-exec requires execution with an absolute path"); |
| if (rexeced_flag) |
| closefrom(REEXEC_MIN_FREE_FD); |
| else |
| closefrom(REEXEC_DEVCRYPTO_RESERVED_FD); |
| |
| /* If requested, redirect the logs to the specified logfile. */ |
| if (logfile != NULL) |
| log_redirect_stderr_to(logfile); |
| /* |
| * Force logging to stderr until we have loaded the private host |
| * key (unless started from inetd) |
| */ |
| log_init(__progname, |
| options.log_level == SYSLOG_LEVEL_NOT_SET ? |
| SYSLOG_LEVEL_INFO : options.log_level, |
| options.log_facility == SYSLOG_FACILITY_NOT_SET ? |
| SYSLOG_FACILITY_AUTH : options.log_facility, |
| log_stderr || !inetd_flag); |
| |
| /* |
| * Unset KRB5CCNAME, otherwise the user's session may inherit it from |
| * root's environment |
| */ |
| if (getenv("KRB5CCNAME") != NULL) |
| (void) unsetenv("KRB5CCNAME"); |
| |
| sensitive_data.have_ssh2_key = 0; |
| |
| /* |
| * If we're not doing an extended test do not silently ignore connection |
| * test params. |
| */ |
| if (test_flag < 2 && connection_info != NULL) |
| fatal("Config test connection parameter (-C) provided without " |
| "test mode (-T)"); |
| |
| /* Fetch our configuration */ |
| if ((cfg = sshbuf_new()) == NULL) |
| fatal("%s: sshbuf_new failed", __func__); |
| if (rexeced_flag) { |
| recv_rexec_state(REEXEC_CONFIG_PASS_FD, cfg); |
| if (!debug_flag) { |
| startup_pipe = dup(REEXEC_STARTUP_PIPE_FD); |
| close(REEXEC_STARTUP_PIPE_FD); |
| /* |
| * Signal parent that this child is at a point where |
| * they can go away if they have a SIGHUP pending. |
| */ |
| (void)atomicio(vwrite, startup_pipe, "\0", 1); |
| } |
| } |
| else if (strcasecmp(config_file_name, "none") != 0) |
| load_server_config(config_file_name, cfg); |
| |
| parse_server_config(&options, rexeced_flag ? "rexec" : config_file_name, |
| cfg, NULL); |
| |
| /* Fill in default values for those options not explicitly set. */ |
| fill_default_server_options(&options); |
| |
| /* challenge-response is implemented via keyboard interactive */ |
| if (options.challenge_response_authentication) |
| options.kbd_interactive_authentication = 1; |
| |
| /* Check that options are sensible */ |
| if (options.authorized_keys_command_user == NULL && |
| (options.authorized_keys_command != NULL && |
| strcasecmp(options.authorized_keys_command, "none") != 0)) |
| fatal("AuthorizedKeysCommand set without " |
| "AuthorizedKeysCommandUser"); |
| if (options.authorized_principals_command_user == NULL && |
| (options.authorized_principals_command != NULL && |
| strcasecmp(options.authorized_principals_command, "none") != 0)) |
| fatal("AuthorizedPrincipalsCommand set without " |
| "AuthorizedPrincipalsCommandUser"); |
| |
| /* |
| * Check whether there is any path through configured auth methods. |
| * Unfortunately it is not possible to verify this generally before |
| * daemonisation in the presence of Match block, but this catches |
| * and warns for trivial misconfigurations that could break login. |
| */ |
| if (options.num_auth_methods != 0) { |
| for (i = 0; i < options.num_auth_methods; i++) { |
| if (auth2_methods_valid(options.auth_methods[i], |
| 1) == 0) |
| break; |
| } |
| if (i >= options.num_auth_methods) |
| fatal("AuthenticationMethods cannot be satisfied by " |
| "enabled authentication methods"); |
| } |
| |
| /* Check that there are no remaining arguments. */ |
| if (optind < ac) { |
| fprintf(stderr, "Extra argument %s.\n", av[optind]); |
| exit(1); |
| } |
| |
| debug("sshd version %s, %s", SSH_VERSION, |
| #ifdef WITH_OPENSSL |
| OpenSSL_version(OPENSSL_VERSION) |
| #else |
| "without OpenSSL" |
| #endif |
| ); |
| |
| /* Store privilege separation user for later use if required. */ |
| privsep_chroot = use_privsep && (getuid() == 0 || geteuid() == 0); |
| if ((privsep_pw = getpwnam(SSH_PRIVSEP_USER)) == NULL) { |
| if (privsep_chroot || options.kerberos_authentication) |
| fatal("Privilege separation user %s does not exist", |
| SSH_PRIVSEP_USER); |
| } else { |
| privsep_pw = pwcopy(privsep_pw); |
| freezero(privsep_pw->pw_passwd, strlen(privsep_pw->pw_passwd)); |
| privsep_pw->pw_passwd = xstrdup("*"); |
| } |
| endpwent(); |
| |
| /* load host keys */ |
| sensitive_data.host_keys = xcalloc(options.num_host_key_files, |
| sizeof(struct sshkey *)); |
| sensitive_data.host_pubkeys = xcalloc(options.num_host_key_files, |
| sizeof(struct sshkey *)); |
| |
| if (options.host_key_agent) { |
| if (strcmp(options.host_key_agent, SSH_AUTHSOCKET_ENV_NAME)) |
| setenv(SSH_AUTHSOCKET_ENV_NAME, |
| options.host_key_agent, 1); |
| if ((r = ssh_get_authentication_socket(NULL)) == 0) |
| have_agent = 1; |
| else |
| error("Could not connect to agent \"%s\": %s", |
| options.host_key_agent, ssh_err(r)); |
| } |
| |
| for (i = 0; i < options.num_host_key_files; i++) { |
| int ll = options.host_key_file_userprovided[i] ? |
| SYSLOG_LEVEL_ERROR : SYSLOG_LEVEL_DEBUG1; |
| |
| if (options.host_key_files[i] == NULL) |
| continue; |
| if ((r = sshkey_load_private(options.host_key_files[i], "", |
| &key, NULL)) != 0 && r != SSH_ERR_SYSTEM_ERROR) |
| do_log2(ll, "Unable to load host key \"%s\": %s", |
| options.host_key_files[i], ssh_err(r)); |
| if (r == 0 && (r = sshkey_shield_private(key)) != 0) { |
| do_log2(ll, "Unable to shield host key \"%s\": %s", |
| options.host_key_files[i], ssh_err(r)); |
| sshkey_free(key); |
| key = NULL; |
| } |
| if ((r = sshkey_load_public(options.host_key_files[i], |
| &pubkey, NULL)) != 0 && r != SSH_ERR_SYSTEM_ERROR) |
| do_log2(ll, "Unable to load host key \"%s\": %s", |
| options.host_key_files[i], ssh_err(r)); |
| if (pubkey == NULL && key != NULL) |
| if ((r = sshkey_from_private(key, &pubkey)) != 0) |
| fatal("Could not demote key: \"%s\": %s", |
| options.host_key_files[i], ssh_err(r)); |
| sensitive_data.host_keys[i] = key; |
| sensitive_data.host_pubkeys[i] = pubkey; |
| |
| if (key == NULL && pubkey != NULL && have_agent) { |
| debug("will rely on agent for hostkey %s", |
| options.host_key_files[i]); |
| keytype = pubkey->type; |
| } else if (key != NULL) { |
| keytype = key->type; |
| accumulate_host_timing_secret(cfg, key); |
| } else { |
| do_log2(ll, "Unable to load host key: %s", |
| options.host_key_files[i]); |
| sensitive_data.host_keys[i] = NULL; |
| sensitive_data.host_pubkeys[i] = NULL; |
| continue; |
| } |
| |
| switch (keytype) { |
| case KEY_RSA: |
| case KEY_DSA: |
| case KEY_ECDSA: |
| case KEY_ED25519: |
| case KEY_XMSS: |
| if (have_agent || key != NULL) |
| sensitive_data.have_ssh2_key = 1; |
| break; |
| } |
| if ((fp = sshkey_fingerprint(pubkey, options.fingerprint_hash, |
| SSH_FP_DEFAULT)) == NULL) |
| fatal("sshkey_fingerprint failed"); |
| debug("%s host key #%d: %s %s", |
| key ? "private" : "agent", i, sshkey_ssh_name(pubkey), fp); |
| free(fp); |
| } |
| accumulate_host_timing_secret(cfg, NULL); |
| if (!sensitive_data.have_ssh2_key) { |
| logit("sshd: no hostkeys available -- exiting."); |
| exit(1); |
| } |
| |
| /* |
| * Load certificates. They are stored in an array at identical |
| * indices to the public keys that they relate to. |
| */ |
| sensitive_data.host_certificates = xcalloc(options.num_host_key_files, |
| sizeof(struct sshkey *)); |
| for (i = 0; i < options.num_host_key_files; i++) |
| sensitive_data.host_certificates[i] = NULL; |
| |
| for (i = 0; i < options.num_host_cert_files; i++) { |
| if (options.host_cert_files[i] == NULL) |
| continue; |
| if ((r = sshkey_load_public(options.host_cert_files[i], |
| &key, NULL)) != 0) { |
| error("Could not load host certificate \"%s\": %s", |
| options.host_cert_files[i], ssh_err(r)); |
| continue; |
| } |
| if (!sshkey_is_cert(key)) { |
| error("Certificate file is not a certificate: %s", |
| options.host_cert_files[i]); |
| sshkey_free(key); |
| continue; |
| } |
| /* Find matching private key */ |
| for (j = 0; j < options.num_host_key_files; j++) { |
| if (sshkey_equal_public(key, |
| sensitive_data.host_keys[j])) { |
| sensitive_data.host_certificates[j] = key; |
| break; |
| } |
| } |
| if (j >= options.num_host_key_files) { |
| error("No matching private key for certificate: %s", |
| options.host_cert_files[i]); |
| sshkey_free(key); |
| continue; |
| } |
| sensitive_data.host_certificates[j] = key; |
| debug("host certificate: #%u type %d %s", j, key->type, |
| sshkey_type(key)); |
| } |
| |
| if (privsep_chroot) { |
| struct stat st; |
| |
| if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) || |
| (S_ISDIR(st.st_mode) == 0)) |
| fatal("Missing privilege separation directory: %s", |
| _PATH_PRIVSEP_CHROOT_DIR); |
| |
| #ifdef HAVE_CYGWIN |
| if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) && |
| (st.st_uid != getuid () || |
| (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)) |
| #else |
| if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0) |
| #endif |
| fatal("%s must be owned by root and not group or " |
| "world-writable.", _PATH_PRIVSEP_CHROOT_DIR); |
| } |
| |
| if (test_flag > 1) { |
| /* |
| * If no connection info was provided by -C then use |
| * use a blank one that will cause no predicate to match. |
| */ |
| if (connection_info == NULL) |
| connection_info = get_connection_info(ssh, 0, 0); |
| connection_info->test = 1; |
| parse_server_match_config(&options, connection_info); |
| dump_config(&options); |
| } |
| |
| /* Configuration looks good, so exit if in test mode. */ |
| if (test_flag) |
| exit(0); |
| |
| /* |
| * Clear out any supplemental groups we may have inherited. This |
| * prevents inadvertent creation of files with bad modes (in the |
| * portable version at least, it's certainly possible for PAM |
| * to create a file, and we can't control the code in every |
| * module which might be used). |
| */ |
| if (setgroups(0, NULL) < 0) |
| debug("setgroups() failed: %.200s", strerror(errno)); |
| |
| if (rexec_flag) { |
| if (rexec_argc < 0) |
| fatal("rexec_argc %d < 0", rexec_argc); |
| rexec_argv = xcalloc(rexec_argc + 2, sizeof(char *)); |
| for (i = 0; i < (u_int)rexec_argc; i++) { |
| debug("rexec_argv[%d]='%s'", i, saved_argv[i]); |
| rexec_argv[i] = saved_argv[i]; |
| } |
| rexec_argv[rexec_argc] = "-R"; |
| rexec_argv[rexec_argc + 1] = NULL; |
| } |
| |
| /* Ensure that umask disallows at least group and world write */ |
| new_umask = umask(0077) | 0022; |
| (void) umask(new_umask); |
| |
| /* Initialize the log (it is reinitialized below in case we forked). */ |
| if (debug_flag && (!inetd_flag || rexeced_flag)) |
| log_stderr = 1; |
| log_init(__progname, options.log_level, options.log_facility, log_stderr); |
| |
| /* |
| * If not in debugging mode, not started from inetd and not already |
| * daemonized (eg re-exec via SIGHUP), disconnect from the controlling |
| * terminal, and fork. The original process exits. |
| */ |
| already_daemon = daemonized(); |
| if (!(debug_flag || inetd_flag || no_daemon_flag || already_daemon)) { |
| |
| if (daemon(0, 0) == -1) |
| fatal("daemon() failed: %.200s", strerror(errno)); |
| |
| disconnect_controlling_tty(); |
| } |
| /* Reinitialize the log (because of the fork above). */ |
| log_init(__progname, options.log_level, options.log_facility, log_stderr); |
| |
| /* Chdir to the root directory so that the current disk can be |
| unmounted if desired. */ |
| if (chdir("/") == -1) |
| error("chdir(\"/\"): %s", strerror(errno)); |
| |
| /* ignore SIGPIPE */ |
| signal(SIGPIPE, SIG_IGN); |
| |
| /* Get a connection, either from inetd or a listening TCP socket */ |
| if (inetd_flag) { |
| server_accept_inetd(&sock_in, &sock_out); |
| } else { |
| platform_pre_listen(); |
| server_listen(); |
| |
| signal(SIGHUP, sighup_handler); |
| signal(SIGCHLD, main_sigchld_handler); |
| signal(SIGTERM, sigterm_handler); |
| signal(SIGQUIT, sigterm_handler); |
| |
| /* |
| * Write out the pid file after the sigterm handler |
| * is setup and the listen sockets are bound |
| */ |
| if (options.pid_file != NULL && !debug_flag) { |
| FILE *f = fopen(options.pid_file, "w"); |
| |
| if (f == NULL) { |
| error("Couldn't create pid file \"%s\": %s", |
| options.pid_file, strerror(errno)); |
| } else { |
| fprintf(f, "%ld\n", (long) getpid()); |
| fclose(f); |
| } |
| } |
| |
| /* Accept a connection and return in a forked child */ |
| server_accept_loop(&sock_in, &sock_out, |
| &newsock, config_s); |
| } |
| |
| /* This is the child processing a new connection. */ |
| setproctitle("%s", "[accepted]"); |
| |
| /* |
| * Create a new session and process group since the 4.4BSD |
| * setlogin() affects the entire process group. We don't |
| * want the child to be able to affect the parent. |
| */ |
| #if !defined(SSHD_ACQUIRES_CTTY) |
| /* |
| * If setsid is called, on some platforms sshd will later acquire a |
| * controlling terminal which will result in "could not set |
| * controlling tty" errors. |
| */ |
| if (!debug_flag && !inetd_flag && setsid() == -1) |
| error("setsid: %.100s", strerror(errno)); |
| #endif |
| |
| if (rexec_flag) { |
| int fd; |
| |
| debug("rexec start in %d out %d newsock %d pipe %d sock %d", |
| sock_in, sock_out, newsock, startup_pipe, config_s[0]); |
| dup2(newsock, STDIN_FILENO); |
| dup2(STDIN_FILENO, STDOUT_FILENO); |
| if (startup_pipe == -1) |
| close(REEXEC_STARTUP_PIPE_FD); |
| else if (startup_pipe != REEXEC_STARTUP_PIPE_FD) { |
| dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD); |
| close(startup_pipe); |
| startup_pipe = REEXEC_STARTUP_PIPE_FD; |
| } |
| |
| dup2(config_s[1], REEXEC_CONFIG_PASS_FD); |
| close(config_s[1]); |
| |
| execv(rexec_argv[0], rexec_argv); |
| |
| /* Reexec has failed, fall back and continue */ |
| error("rexec of %s failed: %s", rexec_argv[0], strerror(errno)); |
| recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL); |
| log_init(__progname, options.log_level, |
| options.log_facility, log_stderr); |
| |
| /* Clean up fds */ |
| close(REEXEC_CONFIG_PASS_FD); |
| newsock = sock_out = sock_in = dup(STDIN_FILENO); |
| if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) { |
| dup2(fd, STDIN_FILENO); |
| dup2(fd, STDOUT_FILENO); |
| if (fd > STDERR_FILENO) |
| close(fd); |
| } |
| debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d", |
| sock_in, sock_out, newsock, startup_pipe, config_s[0]); |
| } |
| |
| /* Executed child processes don't need these. */ |
| fcntl(sock_out, F_SETFD, FD_CLOEXEC); |
| fcntl(sock_in, F_SETFD, FD_CLOEXEC); |
| |
| /* |
| * Disable the key regeneration alarm. We will not regenerate the |
| * key since we are no longer in a position to give it to anyone. We |
| * will not restart on SIGHUP since it no longer makes sense. |
| */ |
| alarm(0); |
| signal(SIGALRM, SIG_DFL); |
| signal(SIGHUP, SIG_DFL); |
| signal(SIGTERM, SIG_DFL); |
| signal(SIGQUIT, SIG_DFL); |
| signal(SIGCHLD, SIG_DFL); |
| signal(SIGINT, SIG_DFL); |
| |
| /* |
| * Register our connection. This turns encryption off because we do |
| * not have a key. |
| */ |
| if ((ssh = ssh_packet_set_connection(NULL, sock_in, sock_out)) == NULL) |
| fatal("Unable to create connection"); |
| the_active_state = ssh; |
| ssh_packet_set_server(ssh); |
| |
| check_ip_options(ssh); |
| |
| /* Prepare the channels layer */ |
| channel_init_channels(ssh); |
| channel_set_af(ssh, options.address_family); |
| process_permitopen(ssh, &options); |
| |
| /* Set SO_KEEPALIVE if requested. */ |
| if (options.tcp_keep_alive && ssh_packet_connection_is_on_socket(ssh) && |
| setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) == -1) |
| error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno)); |
| |
| if ((remote_port = ssh_remote_port(ssh)) < 0) { |
| debug("ssh_remote_port failed"); |
| cleanup_exit(255); |
| } |
| |
| if (options.routing_domain != NULL) |
| set_process_rdomain(ssh, options.routing_domain); |
| |
| /* |
| * The rest of the code depends on the fact that |
| * ssh_remote_ipaddr() caches the remote ip, even if |
| * the socket goes away. |
| */ |
| remote_ip = ssh_remote_ipaddr(ssh); |
| |
| #ifdef SSH_AUDIT_EVENTS |
| audit_connection_from(remote_ip, remote_port); |
| #endif |
| |
| rdomain = ssh_packet_rdomain_in(ssh); |
| |
| /* Log the connection. */ |
| laddr = get_local_ipaddr(sock_in); |
| verbose("Connection from %s port %d on %s port %d%s%s%s", |
| remote_ip, remote_port, laddr, ssh_local_port(ssh), |
| rdomain == NULL ? "" : " rdomain \"", |
| rdomain == NULL ? "" : rdomain, |
| rdomain == NULL ? "" : "\""); |
| free(laddr); |
| |
| /* |
| * We don't want to listen forever unless the other side |
| * successfully authenticates itself. So we set up an alarm which is |
| * cleared after successful authentication. A limit of zero |
| * indicates no limit. Note that we don't set the alarm in debugging |
| * mode; it is just annoying to have the server exit just when you |
| * are about to discover the bug. |
| */ |
| signal(SIGALRM, grace_alarm_handler); |
| if (!debug_flag) |
| alarm(options.login_grace_time); |
| |
| if (kex_exchange_identification(ssh, -1, options.version_addendum) != 0) |
| cleanup_exit(255); /* error already logged */ |
| |
| ssh_packet_set_nonblocking(ssh); |
| |
| /* allocate authentication context */ |
| authctxt = xcalloc(1, sizeof(*authctxt)); |
| ssh->authctxt = authctxt; |
| |
| authctxt->loginmsg = loginmsg; |
| |
| /* XXX global for cleanup, access from other modules */ |
| the_authctxt = authctxt; |
| |
| /* Set default key authentication options */ |
| if ((auth_opts = sshauthopt_new_with_keys_defaults()) == NULL) |
| fatal("allocation failed"); |
| |
| /* prepare buffer to collect messages to display to user after login */ |
| if ((loginmsg = sshbuf_new()) == NULL) |
| fatal("%s: sshbuf_new failed", __func__); |
| auth_debug_reset(); |
| |
| if (use_privsep) { |
| if (privsep_preauth(ssh) == 1) |
| goto authenticated; |
| } else if (have_agent) { |
| if ((r = ssh_get_authentication_socket(&auth_sock)) != 0) { |
| error("Unable to get agent socket: %s", ssh_err(r)); |
| have_agent = 0; |
| } |
| } |
| |
| /* perform the key exchange */ |
| /* authenticate user and start session */ |
| do_ssh2_kex(ssh); |
| do_authentication2(ssh); |
| |
| /* |
| * If we use privilege separation, the unprivileged child transfers |
| * the current keystate and exits |
| */ |
| if (use_privsep) { |
| mm_send_keystate(ssh, pmonitor); |
| ssh_packet_clear_keys(ssh); |
| exit(0); |
| } |
| |
| authenticated: |
| /* |
| * Cancel the alarm we set to limit the time taken for |
| * authentication. |
| */ |
| alarm(0); |
| signal(SIGALRM, SIG_DFL); |
| authctxt->authenticated = 1; |
| if (startup_pipe != -1) { |
| close(startup_pipe); |
| startup_pipe = -1; |
| } |
| |
| #ifdef SSH_AUDIT_EVENTS |
| audit_event(ssh, SSH_AUTH_SUCCESS); |
| #endif |
| |
| #ifdef GSSAPI |
| if (options.gss_authentication) { |
| temporarily_use_uid(authctxt->pw); |
| ssh_gssapi_storecreds(); |
| restore_uid(); |
| } |
| #endif |
| #ifdef USE_PAM |
| if (options.use_pam) { |
| do_pam_setcred(1); |
| do_pam_session(ssh); |
| } |
| #endif |
| |
| /* |
| * In privilege separation, we fork another child and prepare |
| * file descriptor passing. |
| */ |
| if (use_privsep) { |
| privsep_postauth(ssh, authctxt); |
| /* the monitor process [priv] will not return */ |
| } |
| |
| ssh_packet_set_timeout(ssh, options.client_alive_interval, |
| options.client_alive_count_max); |
| |
| /* Try to send all our hostkeys to the client */ |
| notify_hostkeys(ssh); |
| |
| /* Start session. */ |
| do_authenticated(ssh, authctxt); |
| |
| /* The connection has been terminated. */ |
| ssh_packet_get_bytes(ssh, &ibytes, &obytes); |
| verbose("Transferred: sent %llu, received %llu bytes", |
| (unsigned long long)obytes, (unsigned long long)ibytes); |
| |
| verbose("Closing connection to %.500s port %d", remote_ip, remote_port); |
| |
| #ifdef USE_PAM |
| if (options.use_pam) |
| finish_pam(); |
| #endif /* USE_PAM */ |
| |
| #ifdef SSH_AUDIT_EVENTS |
| PRIVSEP(audit_event(ssh, SSH_CONNECTION_CLOSE)); |
| #endif |
| |
| ssh_packet_close(ssh); |
| |
| if (use_privsep) |
| mm_terminate(); |
| |
| exit(0); |
| } |
| |
| int |
| sshd_hostkey_sign(struct ssh *ssh, struct sshkey *privkey, |
| struct sshkey *pubkey, u_char **signature, size_t *slenp, |
| const u_char *data, size_t dlen, const char *alg) |
| { |
| int r; |
| |
| if (use_privsep) { |
| if (privkey) { |
| if (mm_sshkey_sign(ssh, privkey, signature, slenp, |
| data, dlen, alg, NULL, ssh->compat) < 0) |
| fatal("%s: privkey sign failed", __func__); |
| } else { |
| if (mm_sshkey_sign(ssh, pubkey, signature, slenp, |
| data, dlen, alg, NULL, ssh->compat) < 0) |
| fatal("%s: pubkey sign failed", __func__); |
| } |
| } else { |
| if (privkey) { |
| if (sshkey_sign(privkey, signature, slenp, data, dlen, |
| alg, NULL, ssh->compat) < 0) |
| fatal("%s: privkey sign failed", __func__); |
| } else { |
| if ((r = ssh_agent_sign(auth_sock, pubkey, |
| signature, slenp, data, dlen, alg, |
| ssh->compat)) != 0) { |
| fatal("%s: agent sign failed: %s", |
| __func__, ssh_err(r)); |
| } |
| } |
| } |
| return 0; |
| } |
| |
| /* SSH2 key exchange */ |
| static void |
| do_ssh2_kex(struct ssh *ssh) |
| { |
| char *myproposal[PROPOSAL_MAX] = { KEX_SERVER }; |
| struct kex *kex; |
| int r; |
| |
| myproposal[PROPOSAL_KEX_ALGS] = compat_kex_proposal( |
| options.kex_algorithms); |
| myproposal[PROPOSAL_ENC_ALGS_CTOS] = compat_cipher_proposal( |
| options.ciphers); |
| myproposal[PROPOSAL_ENC_ALGS_STOC] = compat_cipher_proposal( |
| options.ciphers); |
| myproposal[PROPOSAL_MAC_ALGS_CTOS] = |
| myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs; |
| |
| if (options.compression == COMP_NONE) { |
| myproposal[PROPOSAL_COMP_ALGS_CTOS] = |
| myproposal[PROPOSAL_COMP_ALGS_STOC] = "none"; |
| } |
| |
| if (options.rekey_limit || options.rekey_interval) |
| ssh_packet_set_rekey_limits(ssh, options.rekey_limit, |
| options.rekey_interval); |
| |
| myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = compat_pkalg_proposal( |
| list_hostkey_types()); |
| |
| /* start key exchange */ |
| if ((r = kex_setup(ssh, myproposal)) != 0) |
| fatal("kex_setup: %s", ssh_err(r)); |
| kex = ssh->kex; |
| #ifdef WITH_OPENSSL |
| kex->kex[KEX_DH_GRP1_SHA1] = kex_gen_server; |
| kex->kex[KEX_DH_GRP14_SHA1] = kex_gen_server; |
| kex->kex[KEX_DH_GRP14_SHA256] = kex_gen_server; |
| kex->kex[KEX_DH_GRP16_SHA512] = kex_gen_server; |
| kex->kex[KEX_DH_GRP18_SHA512] = kex_gen_server; |
| kex->kex[KEX_DH_GEX_SHA1] = kexgex_server; |
| kex->kex[KEX_DH_GEX_SHA256] = kexgex_server; |
| # ifdef OPENSSL_HAS_ECC |
| kex->kex[KEX_ECDH_SHA2] = kex_gen_server; |
| # endif |
| #endif |
| kex->kex[KEX_C25519_SHA256] = kex_gen_server; |
| kex->kex[KEX_KEM_SNTRUP4591761X25519_SHA512] = kex_gen_server; |
| kex->load_host_public_key=&get_hostkey_public_by_type; |
| kex->load_host_private_key=&get_hostkey_private_by_type; |
| kex->host_key_index=&get_hostkey_index; |
| kex->sign = sshd_hostkey_sign; |
| |
| ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &kex->done); |
| |
| session_id2 = kex->session_id; |
| session_id2_len = kex->session_id_len; |
| |
| #ifdef DEBUG_KEXDH |
| /* send 1st encrypted/maced/compressed message */ |
| packet_start(SSH2_MSG_IGNORE); |
| packet_put_cstring("markus"); |
| packet_send(); |
| packet_write_wait(); |
| #endif |
| debug("KEX done"); |
| } |
| |
| /* server specific fatal cleanup */ |
| void |
| cleanup_exit(int i) |
| { |
| if (the_active_state != NULL && the_authctxt != NULL) { |
| do_cleanup(the_active_state, the_authctxt); |
| if (use_privsep && privsep_is_preauth && |
| pmonitor != NULL && pmonitor->m_pid > 1) { |
| debug("Killing privsep child %d", pmonitor->m_pid); |
| if (kill(pmonitor->m_pid, SIGKILL) != 0 && |
| errno != ESRCH) |
| error("%s: kill(%d): %s", __func__, |
| pmonitor->m_pid, strerror(errno)); |
| } |
| } |
| #ifdef SSH_AUDIT_EVENTS |
| /* done after do_cleanup so it can cancel the PAM auth 'thread' */ |
| if (the_active_state != NULL && (!use_privsep || mm_is_monitor())) |
| audit_event(the_active_state, SSH_CONNECTION_ABANDON); |
| #endif |
| _exit(i); |
| } |