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sshd.c
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/* $OpenBSD: sshd.c,v 1.609 2024/06/27 23:01:15 djm Exp $ */
/*
* 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>
#ifdef HAVE_POLL_H
#include <poll.h>
#endif
#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/evp.h>
#include <openssl/rand.h>
#include "openbsd-compat/openssl-compat.h"
#endif
#ifdef HAVE_SECUREWARE
#include <sys/security.h>
#include <prot.h>
#endif
#ifdef WINDOWS
#include "sshTelemetry.h"
#endif
#include "xmalloc.h"
#include "ssh.h"
#include "sshpty.h"
#include "log.h"
#include "sshbuf.h"
#include "misc.h"
#include "servconf.h"
#include "compat.h"
#include "digest.h"
#include "sshkey.h"
#include "authfile.h"
#include "pathnames.h"
#include "canohost.h"
#include "hostfile.h"
#include "auth.h"
#include "authfd.h"
#include "msg.h"
#include "version.h"
#include "ssherr.h"
#include "sk-api.h"
#include "addr.h"
#include "srclimit.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)
/* Privilege separation related spawn fds */
#define PRIVSEP_MONITOR_FD (STDERR_FILENO + 1)
#define PRIVSEP_LOG_FD (STDERR_FILENO + 2)
#define PRIVSEP_UNAUTH_MIN_FREE_FD (PRIVSEP_LOG_FD + 1)
#ifdef WINDOWS
#define PRIVSEP_AUTH_MIN_FREE_FD (PRIVSEP_LOG_FD + 1)
#else
#define PRIVSEP_AUTH_MIN_FREE_FD (PRIVSEP_MONITOR_FD + 1)
#endif
extern char *__progname;
/* Server configuration options. */
ServerOptions options;
/*
* 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;
#ifdef WINDOWS
debug_startup_p = -1;
#endif /* WINDOWS */
/* Saved arguments to main(). */
static char **saved_argv;
static int saved_argc;
#ifdef WINDOWS
static char** rexec_argv;
#endif /* WINDOWS */
/*
* 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;
/*
* 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_siginfo = 0;
static volatile sig_atomic_t received_sigchld = 0;
static volatile sig_atomic_t received_sighup = 0;
static volatile sig_atomic_t received_sigterm = 0;
/* record remote hostname or ip */
u_int utmp_len = HOST_NAME_MAX+1;
/*
* The early_child/children array below is used for tracking children of the
* listening sshd process early in their lifespans, before they have
* completed authentication. This tracking is needed for four 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.
* 4) Tracking and logging unsuccessful exits from the preauth sshd monitor,
* including and especially those for LoginGraceTime timeouts.
*
* 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 sending a
* second char over the socket before closing it, otherwise the listener will
* continue tracking the child (and using up a MaxStartups slot) until the
* preauth subprocess exits, whereupon the listener will log its exit status.
* preauth processes will exit with a status of EXIT_LOGIN_GRACE to indicate
* they did not authenticate before the LoginGraceTime alarm fired.
*/
struct early_child {
int pipefd;
int early; /* Indicates child closed listener */
char *id; /* human readable connection identifier */
pid_t pid;
struct xaddr addr;
int have_addr;
int status, have_status;
};
static struct early_child *children;
static int children_active;
static int startup_pipe = -1; /* in child */
/* sshd_config buffer */
struct sshbuf *cfg;
/* Included files from the configuration file */
struct include_list includes = TAILQ_HEAD_INITIALIZER(includes);
/* message to be displayed after login */
struct sshbuf *loginmsg;
/* Unprivileged user */
struct passwd *privsep_pw = NULL;
static char *listener_proctitle;
/*
* 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 = 0;
}
/* Allocate and initialise the children array */
static void
child_alloc(void)
{
int i;
children = xcalloc(options.max_startups, sizeof(*children));
for (i = 0; i < options.max_startups; i++) {
children[i].pipefd = -1;
children[i].pid = -1;
}
}
/* Register a new connection in the children array; child pid comes later */
static struct early_child *
child_register(int pipefd, int sockfd)
{
int i, lport, rport;
char *laddr = NULL, *raddr = NULL;
struct early_child *child = NULL;
struct sockaddr_storage addr;
socklen_t addrlen = sizeof(addr);
struct sockaddr *sa = (struct sockaddr *)&addr;
for (i = 0; i < options.max_startups; i++) {
if (children[i].pipefd != -1 || children[i].pid > 0)
continue;
child = &(children[i]);
break;
}
if (child == NULL) {
fatal_f("error: accepted connection when all %d child "
" slots full", options.max_startups);
}
child->pipefd = pipefd;
child->early = 1;
/* record peer address, if available */
if (getpeername(sockfd, sa, &addrlen) == 0 &&
addr_sa_to_xaddr(sa, addrlen, &child->addr) == 0)
child->have_addr = 1;
/* format peer address string for logs */
if ((lport = get_local_port(sockfd)) == 0 ||
(rport = get_peer_port(sockfd)) == 0) {
/* Not a TCP socket */
raddr = get_peer_ipaddr(sockfd);
xasprintf(&child->id, "connection from %s", raddr);
} else {
laddr = get_local_ipaddr(sockfd);
raddr = get_peer_ipaddr(sockfd);
xasprintf(&child->id, "connection from %s to %s", laddr, raddr);
}
free(laddr);
free(raddr);
if (++children_active > options.max_startups)
fatal_f("internal error: more children than max_startups");
return child;
}
/*
* Finally free a child entry. Don't call this directly.
*/
static void
child_finish(struct early_child *child)
{
if (children_active == 0)
fatal_f("internal error: children_active underflow");
if (child->pipefd != -1)
close(child->pipefd);
free(child->id);
memset(child, '\0', sizeof(*child));
child->pipefd = -1;
child->pid = -1;
children_active--;
}
/*
* Close a child's pipe. This will not stop tracking the child immediately
* (it will still be tracked for waitpid()) unless force_final is set, or
* child has already exited.
*/
static void
child_close(struct early_child *child, int force_final, int quiet)
{
if (!quiet)
debug_f("enter%s", force_final ? " (forcing)" : "");
if (child->pipefd != -1) {
close(child->pipefd);
child->pipefd = -1;
}
if (child->pid == -1 || force_final)
child_finish(child);
}
/* Record a child exit. Safe to call from signal handlers */
static void
child_exit(pid_t pid, int status)
{
int i;
if (children == NULL || pid <= 0)
return;
for (i = 0; i < options.max_startups; i++) {
if (children[i].pid == pid) {
children[i].have_status = 1;
children[i].status = status;
break;
}
}
}
/*
* Reap a child entry that has exited, as previously flagged
* using child_exit().
* Handles logging of exit condition and will finalise the child if its pipe
* had already been closed.
*/
static void
child_reap(struct early_child *child)
{
LogLevel level = SYSLOG_LEVEL_DEBUG1;
int was_crash, penalty_type = SRCLIMIT_PENALTY_NONE;
/* Log exit information */
if (WIFSIGNALED(child->status)) {
/*
* Increase logging for signals potentially associated
* with serious conditions.
*/
if ((was_crash = signal_is_crash(WTERMSIG(child->status))))
level = SYSLOG_LEVEL_ERROR;
do_log2(level, "session process %ld for %s killed by "
"signal %d%s", (long)child->pid, child->id,
WTERMSIG(child->status), child->early ? " (early)" : "");
if (was_crash)
penalty_type = SRCLIMIT_PENALTY_CRASH;
} else if (!WIFEXITED(child->status)) {
penalty_type = SRCLIMIT_PENALTY_CRASH;
error("session process %ld for %s terminated abnormally, "
"status=0x%x%s", (long)child->pid, child->id, child->status,
child->early ? " (early)" : "");
} else {
/* Normal exit. We care about the status */
switch (WEXITSTATUS(child->status)) {
case 0:
debug3_f("preauth child %ld for %s completed "
"normally %s", (long)child->pid, child->id,
child->early ? " (early)" : "");
break;
case EXIT_LOGIN_GRACE:
penalty_type = SRCLIMIT_PENALTY_GRACE_EXCEEDED;
logit("Timeout before authentication for %s, "
"pid = %ld%s", child->id, (long)child->pid,
child->early ? " (early)" : "");
break;
case EXIT_CHILD_CRASH:
penalty_type = SRCLIMIT_PENALTY_CRASH;
logit("Session process %ld unpriv child crash for %s%s",
(long)child->pid, child->id,
child->early ? " (early)" : "");
break;
case EXIT_AUTH_ATTEMPTED:
penalty_type = SRCLIMIT_PENALTY_AUTHFAIL;
debug_f("preauth child %ld for %s exited "
"after unsuccessful auth attempt %s",
(long)child->pid, child->id,
child->early ? " (early)" : "");
break;
default:
penalty_type = SRCLIMIT_PENALTY_NOAUTH;
debug_f("preauth child %ld for %s exited "
"with status %d%s", (long)child->pid, child->id,
WEXITSTATUS(child->status),
child->early ? " (early)" : "");
break;
}
}
if (child->have_addr)
srclimit_penalise(&child->addr, penalty_type);
child->pid = -1;
child->have_status = 0;
if (child->pipefd == -1)
child_finish(child);
}
/* Reap all children that have exited; called after SIGCHLD */
static void
child_reap_all_exited(void)
{
int i;
pid_t pid;
int status;
if (children == NULL)
return;
for (;;) {
if ((pid = waitpid(-1, &status, WNOHANG)) == 0)
break;
else if (pid == -1) {
if (errno == EINTR || errno == EAGAIN)
continue;
if (errno != ECHILD)
error_f("waitpid: %s", strerror(errno));
break;
}
child_exit(pid, status);
}
for (i = 0; i < options.max_startups; i++) {
if (!children[i].have_status)
continue;
child_reap(&(children[i]));
}
}
static void
close_startup_pipes(void)
{
int i;
if (children == NULL)
return;
for (i = 0; i < options.max_startups; i++) {
if (children[i].pipefd != -1)
child_close(&(children[i]), 1, 1);
}
}
/* Called after SIGINFO */
static void
show_info(void)
{
int i;
/* XXX print listening sockets here too */
if (children == NULL)
return;
logit("%d active startups", children_active);
for (i = 0; i < options.max_startups; i++) {
if (children[i].pipefd == -1 && children[i].pid <= 0)
continue;
logit("child %d: fd=%d pid=%ld %s%s", i, children[i].pipefd,
(long)children[i].pid, children[i].id,
children[i].early ? " (early)" : "");
}
srclimit_penalty_info();
}
/*
* 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).
*/
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)
{
#ifndef WINDOWS // not applicable to Windows
logit("Received SIGHUP; restarting.");
if (options.pid_file != NULL)
unlink(options.pid_file);
platform_pre_restart();
close_listen_socks();
close_startup_pipes();
ssh_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);
#endif /* WINDOWS */
}
/*
* Generic signal handler for terminating signals in the master daemon.
*/
static void
sigterm_handler(int sig)
{
received_sigterm = sig;
}
#ifdef SIGINFO
static void
siginfo_handler(int sig)
{
received_siginfo = 1;
}
#endif
static void
main_sigchld_handler(int sig)
{
received_sigchld = 1;
}
#ifdef WINDOWS
static void
recv_hostkeys_state(int fd)
{
struct sshbuf *m;
u_char *cp, ver;
struct sshkey *key = NULL;
const u_char *blob;
size_t blen;
int r;
u_int32_t num_host_key_files;
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_u32(m, &num_host_key_files)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
sensitive_data.host_keys = xcalloc(num_host_key_files, sizeof(struct sshkey *));
sensitive_data.host_pubkeys = xcalloc(num_host_key_files, sizeof(struct sshkey *));
sensitive_data.host_certificates = xcalloc(num_host_key_files, sizeof(struct sshkey *));
for (int i = 0; i < num_host_key_files; i++) {
if ((r = sshbuf_get_string_direct(m, &blob, &blen)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
sensitive_data.host_pubkeys[i] = NULL;
sensitive_data.host_keys[i] = NULL;
if (blen) {
sshkey_from_blob(blob, blen, &key);
sensitive_data.host_pubkeys[i] = key;
}
}
for (int i = 0; i < num_host_key_files; i++) {
if ((r = sshbuf_get_string_direct(m, &blob, &blen)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
sensitive_data.host_certificates[i] = NULL;
if (blen) {
sshkey_from_blob(blob, blen, &key);
sensitive_data.host_certificates[i] = key;
}
}
sshbuf_free(m);
debug3("%s: done", __func__);
}
#endif
/*
* 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
should_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_f("p %d, r %d", p, r);
return (r < p) ? 1 : 0;
}
/*
* Check whether connection should be accepted by MaxStartups or for penalty.
* Returns 0 if the connection is accepted. If the connection is refused,
* returns 1 and attempts to send notification to client.
* Logs when the MaxStartups condition is entered or exited, and periodically
* while in that state.
*/
static int
drop_connection(int sock, int startups, int notify_pipe)
{
char *laddr, *raddr;
const char *reason = NULL, msg[] = "Not allowed at this time\r\n";
static time_t last_drop, first_drop;
static u_int ndropped;
LogLevel drop_level = SYSLOG_LEVEL_VERBOSE;
time_t now;
if (!srclimit_penalty_check_allow(sock, &reason)) {
drop_level = SYSLOG_LEVEL_INFO;
goto handle;
}
now = monotime();
if (!should_drop_connection(startups) &&
srclimit_check_allow(sock, notify_pipe) == 1) {
if (last_drop != 0 &&
startups < options.max_startups_begin - 1) {
/* XXX maybe need better hysteresis here */
logit("exited MaxStartups throttling after %s, "
"%u connections dropped",
fmt_timeframe(now - first_drop), ndropped);
last_drop = 0;
}
return 0;
}
#define SSHD_MAXSTARTUPS_LOG_INTERVAL (5 * 60)
if (last_drop == 0) {
error("beginning MaxStartups throttling");
drop_level = SYSLOG_LEVEL_INFO;
first_drop = now;
ndropped = 0;
} else if (last_drop + SSHD_MAXSTARTUPS_LOG_INTERVAL < now) {
/* Periodic logs */
error("in MaxStartups throttling for %s, "
"%u connections dropped",
fmt_timeframe(now - first_drop), ndropped + 1);
drop_level = SYSLOG_LEVEL_INFO;
}
last_drop = now;
ndropped++;
reason = "past Maxstartups";
handle:
laddr = get_local_ipaddr(sock);
raddr = get_peer_ipaddr(sock);
do_log2(drop_level, "drop connection #%d from [%s]:%d on [%s]:%d %s",
startups,
raddr, get_peer_port(sock),
laddr, get_local_port(sock),
reason);
free(laddr);
free(raddr);
/* best-effort notification to client */
(void)write(sock, msg, sizeof(msg) - 1);
return 1;
}
static void
usage(void)
{
fprintf(stderr, "%s, %s\n", SSH_RELEASE, SSH_OPENSSL_VERSION);
fprintf(stderr,
"usage: sshd [-46DdeGiqTtV] [-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 struct sshbuf *
pack_hostkeys(void)
{
struct sshbuf *keybuf = NULL, *hostkeys = NULL;
int r;
u_int i;
if ((keybuf = sshbuf_new()) == NULL ||
(hostkeys = sshbuf_new()) == NULL)
fatal_f("sshbuf_new failed");
/* pack hostkeys into a string. Empty key slots get empty strings */
for (i = 0; i < options.num_host_key_files; i++) {
/* private key */
sshbuf_reset(keybuf);
if (sensitive_data.host_keys[i] != NULL &&
(r = sshkey_private_serialize(sensitive_data.host_keys[i],
keybuf)) != 0)
fatal_fr(r, "serialize hostkey private");
if ((r = sshbuf_put_stringb(hostkeys, keybuf)) != 0)
fatal_fr(r, "compose hostkey private");
/* public key */
if (sensitive_data.host_pubkeys[i] != NULL) {
if ((r = sshkey_puts(sensitive_data.host_pubkeys[i],
hostkeys)) != 0)
fatal_fr(r, "compose hostkey public");
} else {
if ((r = sshbuf_put_string(hostkeys, NULL, 0)) != 0)
fatal_fr(r, "compose hostkey empty public");
}
/* cert */
if (sensitive_data.host_certificates[i] != NULL) {
if ((r = sshkey_puts(
sensitive_data.host_certificates[i],
hostkeys)) != 0)
fatal_fr(r, "compose host cert");
} else {
if ((r = sshbuf_put_string(hostkeys, NULL, 0)) != 0)
fatal_fr(r, "compose host cert empty");
}
}
sshbuf_free(keybuf);
return hostkeys;
}
static void
send_rexec_state(int fd, struct sshbuf *conf)
{
struct sshbuf *m = NULL, *inc = NULL, *hostkeys = NULL;
struct include_item *item = NULL;
int r, sz;
debug3_f("entering fd = %d config len %zu", fd,
sshbuf_len(conf));
if ((m = sshbuf_new()) == NULL ||
(inc = sshbuf_new()) == NULL)
fatal_f("sshbuf_new failed");
/* pack includes into a string */
TAILQ_FOREACH(item, &includes, entry) {
if ((r = sshbuf_put_cstring(inc, item->selector)) != 0 ||
(r = sshbuf_put_cstring(inc, item->filename)) != 0 ||
(r = sshbuf_put_stringb(inc, item->contents)) != 0)
fatal_fr(r, "compose includes");
}
hostkeys = pack_hostkeys();
/*
* Protocol from reexec master to child:
* string configuration
* uint64 timing_secret
* string host_keys[] {
* string private_key
* string public_key
* string certificate
* }
* string included_files[] {
* string selector
* string filename
* string contents
* }
*/
if ((r = sshbuf_put_stringb(m, conf)) != 0 ||
(r = sshbuf_put_u64(m, options.timing_secret)) != 0 ||
(r = sshbuf_put_stringb(m, hostkeys)) != 0 ||
(r = sshbuf_put_stringb(m, inc)) != 0)
fatal_fr(r, "compose config");
#ifndef WINDOWS
/* We need to fit the entire message inside the socket send buffer */
sz = ROUNDUP(sshbuf_len(m) + 5, 16*1024);
if (setsockopt(fd, SOL_SOCKET, SO_SNDBUF, &sz, sizeof sz) == -1)
fatal_f("setsockopt SO_SNDBUF: %s", strerror(errno));
#endif /* WINDOWS */
if (ssh_msg_send(fd, 0, m) == -1)
error_f("ssh_msg_send failed");
sshbuf_free(m);
sshbuf_free(inc);
sshbuf_free(hostkeys);
debug3_f("done");
}
/*
* 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;
/* Initialise per-source limit tracking. */
srclimit_init(options.max_startups,
options.per_source_max_startups,
options.per_source_masklen_ipv4,
options.per_source_masklen_ipv6,
&options.per_source_penalty,
options.per_source_penalty_exempt);
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,
int log_stderr)
{
struct pollfd *pfd = NULL;
int i, ret, npfd;
int oactive = -1, listening = 0, lameduck = 0;
int startup_p[2] = { -1 , -1 }, *startup_pollfd;
char c = 0;
struct sockaddr_storage from;
struct early_child *child;
socklen_t fromlen;
u_char rnd[256];
sigset_t nsigset, osigset;
/* pipes connected to unauthenticated child sshd processes */
child_alloc();
startup_pollfd = xcalloc(options.max_startups, sizeof(int));
/*
* Prepare signal mask that we use to block signals that might set
* received_sigterm/hup/chld/info, so that we are guaranteed
* to immediately wake up the ppoll if a signal is received after
* the flag is checked.
*/
sigemptyset(&nsigset);
sigaddset(&nsigset, SIGHUP);
sigaddset(&nsigset, SIGCHLD);
#ifdef SIGINFO
sigaddset(&nsigset, SIGINFO);
#endif
sigaddset(&nsigset, SIGTERM);
sigaddset(&nsigset, SIGQUIT);
/* sized for worst-case */
pfd = xcalloc(num_listen_socks + options.max_startups,
sizeof(struct pollfd));
/*
* Stay listening for connections until the system crashes or
* the daemon is killed with a signal.
*/
for (;;) {
sigprocmask(SIG_BLOCK, &nsigset, &osigset);
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 (received_sigchld) {
child_reap_all_exited();
received_sigchld = 0;
}
if (received_siginfo) {
show_info();
received_siginfo = 0;
}
if (oactive != children_active) {
setproctitle("%s [listener] %d of %d-%d startups",
listener_proctitle, children_active,
options.max_startups_begin, options.max_startups);
oactive = children_active;
}
if (received_sighup) {
if (!lameduck) {
debug("Received SIGHUP; waiting for children");
close_listen_socks();
lameduck = 1;
}
if (listening <= 0) {
sigprocmask(SIG_SETMASK, &osigset, NULL);
sighup_restart();
}
}