blob: 0b65a45c45077cf65f521385e49c2fcfe6f5ae2b [file] [log] [blame]
/*
* Dropbear - a SSH2 server
*
* Copyright (c) 2002-2006 Matt Johnston
* All rights reserved.
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE. */
#include "includes.h"
#include "dbutil.h"
#include "session.h"
#include "buffer.h"
#include "signkey.h"
#include "runopts.h"
#include "random.h"
static size_t listensockets(int *sock, size_t sockcount, int *maxfd);
static void sigchld_handler(int dummy);
static void sigsegv_handler(int);
static void sigintterm_handler(int fish);
#ifdef INETD_MODE
static void main_inetd();
#endif
#ifdef NON_INETD_MODE
static void main_noinetd();
#endif
static void commonsetup();
#if defined(DBMULTI_dropbear) || !defined(DROPBEAR_MULTI)
#if defined(DBMULTI_dropbear) && defined(DROPBEAR_MULTI)
int dropbear_main(int argc, char ** argv)
#else
int main(int argc, char ** argv)
#endif
{
_dropbear_exit = svr_dropbear_exit;
_dropbear_log = svr_dropbear_log;
disallow_core();
/* get commandline options */
svr_getopts(argc, argv);
#ifdef INETD_MODE
/* service program mode */
if (svr_opts.inetdmode) {
main_inetd();
/* notreached */
}
#endif
#ifdef NON_INETD_MODE
main_noinetd();
/* notreached */
#endif
dropbear_exit("Compiled without normal mode, can't run without -i\n");
return -1;
}
#endif
#ifdef INETD_MODE
static void main_inetd() {
struct sockaddr_storage remoteaddr;
socklen_t remoteaddrlen;
char * addrstring = NULL;
/* Set up handlers, syslog, seed random */
commonsetup();
remoteaddrlen = sizeof(remoteaddr);
if (getpeername(0, (struct sockaddr*)&remoteaddr, &remoteaddrlen) < 0) {
dropbear_exit("Unable to getpeername: %s", strerror(errno));
}
/* In case our inetd was lax in logging source addresses */
addrstring = getaddrstring(&remoteaddr, 1);
dropbear_log(LOG_INFO, "Child connection from %s", addrstring);
/* Don't check the return value - it may just fail since inetd has
* already done setsid() after forking (xinetd on Darwin appears to do
* this */
setsid();
/* Start service program
* -1 is a dummy childpipe, just something we can close() without
* mattering. */
svr_session(0, -1, getaddrhostname(&remoteaddr), addrstring);
/* notreached */
}
#endif /* INETD_MODE */
#ifdef NON_INETD_MODE
void main_noinetd() {
fd_set fds;
struct timeval seltimeout;
unsigned int i, j;
int val;
int maxsock = -1;
int listensocks[MAX_LISTEN_ADDR];
size_t listensockcount = 0;
FILE *pidfile = NULL;
int childpipes[MAX_UNAUTH_CLIENTS];
char * preauth_addrs[MAX_UNAUTH_CLIENTS];
int childsock;
int childpipe[2];
/* Note: commonsetup() must happen before we daemon()ise. Otherwise
daemon() will chdir("/"), and we won't be able to find local-dir
hostkeys. */
commonsetup();
/* fork */
if (svr_opts.forkbg) {
int closefds = 0;
#ifndef DEBUG_TRACE
if (!svr_opts.usingsyslog) {
closefds = 1;
}
#endif
if (daemon(0, closefds) < 0) {
dropbear_exit("Failed to daemonize: %s", strerror(errno));
}
}
/* should be done after syslog is working */
if (svr_opts.forkbg) {
dropbear_log(LOG_INFO, "Running in background");
} else {
dropbear_log(LOG_INFO, "Not forking");
}
/* create a PID file so that we can be killed easily */
pidfile = fopen(svr_opts.pidfile, "w");
if (pidfile) {
fprintf(pidfile, "%d\n", getpid());
fclose(pidfile);
}
/* sockets to identify pre-authenticated clients */
for (i = 0; i < MAX_UNAUTH_CLIENTS; i++) {
childpipes[i] = -1;
}
bzero(preauth_addrs, sizeof(preauth_addrs));
/* Set up the listening sockets */
listensockcount = listensockets(listensocks, MAX_LISTEN_ADDR, &maxsock);
if (listensockcount == 0)
{
dropbear_exit("No listening ports available.");
}
/* incoming connection select loop */
for(;;) {
FD_ZERO(&fds);
seltimeout.tv_sec = 60;
seltimeout.tv_usec = 0;
/* listening sockets */
for (i = 0; i < listensockcount; i++) {
FD_SET(listensocks[i], &fds);
}
/* pre-authentication clients */
for (i = 0; i < MAX_UNAUTH_CLIENTS; i++) {
if (childpipes[i] >= 0) {
FD_SET(childpipes[i], &fds);
maxsock = MAX(maxsock, childpipes[i]);
}
}
val = select(maxsock+1, &fds, NULL, NULL, &seltimeout);
if (exitflag) {
unlink(svr_opts.pidfile);
dropbear_exit("Terminated by signal");
}
if (val == 0) {
/* timeout reached */
continue;
}
if (val < 0) {
if (errno == EINTR) {
continue;
}
dropbear_exit("Listening socket error");
}
/* close fds which have been authed or closed - svr-auth.c handles
* closing the auth sockets on success */
for (i = 0; i < MAX_UNAUTH_CLIENTS; i++) {
if (childpipes[i] >= 0 && FD_ISSET(childpipes[i], &fds)) {
m_close(childpipes[i]);
childpipes[i] = -1;
m_free(preauth_addrs[i]);
}
}
/* handle each socket which has something to say */
for (i = 0; i < listensockcount; i++) {
struct sockaddr_storage remoteaddr;
socklen_t remoteaddrlen = 0;
size_t num_unauthed_for_addr = 0;
size_t num_unauthed_total = 0;
char * remote_addr_str = NULL;
pid_t fork_ret = 0;
size_t conn_idx = 0;
if (!FD_ISSET(listensocks[i], &fds))
continue;
remoteaddrlen = sizeof(remoteaddr);
childsock = accept(listensocks[i],
(struct sockaddr*)&remoteaddr, &remoteaddrlen);
if (childsock < 0) {
/* accept failed */
continue;
}
/* Limit the number of unauthenticated connections per IP */
remote_addr_str = getaddrstring(&remoteaddr, 0);
num_unauthed_for_addr = 0;
num_unauthed_total = 0;
for (j = 0; j < MAX_UNAUTH_CLIENTS; j++) {
if (childpipes[j] >= 0) {
num_unauthed_total++;
if (strcmp(remote_addr_str, preauth_addrs[j]) == 0) {
num_unauthed_for_addr++;
}
} else {
/* a free slot */
conn_idx = j;
}
}
if (num_unauthed_total >= MAX_UNAUTH_CLIENTS
|| num_unauthed_for_addr >= MAX_UNAUTH_PER_IP) {
goto out;
}
if (pipe(childpipe) < 0) {
TRACE(("error creating child pipe"))
goto out;
}
fork_ret = fork();
if (fork_ret < 0) {
dropbear_log(LOG_WARNING, "error forking: %s", strerror(errno));
goto out;
} else if (fork_ret > 0) {
/* parent */
childpipes[conn_idx] = childpipe[0];
m_close(childpipe[1]);
preauth_addrs[conn_idx] = remote_addr_str;
remote_addr_str = NULL;
} else {
/* child */
char * addrstring = NULL;
#ifdef DEBUG_FORKGPROF
extern void _start(void), etext(void);
monstartup((u_long)&_start, (u_long)&etext);
#endif /* DEBUG_FORKGPROF */
m_free(remote_addr_str);
addrstring = getaddrstring(&remoteaddr, 1);
dropbear_log(LOG_INFO, "Child connection from %s", addrstring);
if (setsid() < 0) {
dropbear_exit("setsid: %s", strerror(errno));
}
/* make sure we close sockets */
for (i = 0; i < listensockcount; i++) {
m_close(listensocks[i]);
}
m_close(childpipe[0]);
/* start the session */
svr_session(childsock, childpipe[1],
getaddrhostname(&remoteaddr),
addrstring);
/* don't return */
dropbear_assert(0);
}
out:
/* This section is important for the parent too */
m_close(childsock);
if (remote_addr_str) {
m_free(remote_addr_str);
}
}
} /* for(;;) loop */
/* don't reach here */
}
#endif /* NON_INETD_MODE */
/* catch + reap zombie children */
static void sigchld_handler(int UNUSED(unused)) {
struct sigaction sa_chld;
while(waitpid(-1, NULL, WNOHANG) > 0);
sa_chld.sa_handler = sigchld_handler;
sa_chld.sa_flags = SA_NOCLDSTOP;
if (sigaction(SIGCHLD, &sa_chld, NULL) < 0) {
dropbear_exit("signal() error");
}
}
/* catch any segvs */
static void sigsegv_handler(int UNUSED(unused)) {
fprintf(stderr, "Aiee, segfault! You should probably report "
"this as a bug to the developer\n");
exit(EXIT_FAILURE);
}
/* catch ctrl-c or sigterm */
static void sigintterm_handler(int UNUSED(unused)) {
exitflag = 1;
}
/* Things used by inetd and non-inetd modes */
static void commonsetup() {
struct sigaction sa_chld;
#ifndef DISABLE_SYSLOG
if (svr_opts.usingsyslog) {
startsyslog();
}
#endif
/* set up cleanup handler */
if (signal(SIGINT, sigintterm_handler) == SIG_ERR ||
#ifndef DEBUG_VALGRIND
signal(SIGTERM, sigintterm_handler) == SIG_ERR ||
#endif
signal(SIGPIPE, SIG_IGN) == SIG_ERR) {
dropbear_exit("signal() error");
}
/* catch and reap zombie children */
sa_chld.sa_handler = sigchld_handler;
sa_chld.sa_flags = SA_NOCLDSTOP;
if (sigaction(SIGCHLD, &sa_chld, NULL) < 0) {
dropbear_exit("signal() error");
}
if (signal(SIGSEGV, sigsegv_handler) == SIG_ERR) {
dropbear_exit("signal() error");
}
/* Now we can setup the hostkeys - needs to be after logging is on,
* otherwise we might end up blatting error messages to the socket */
loadhostkeys();
seedrandom();
}
/* Set up listening sockets for all the requested ports */
static size_t listensockets(int *sock, size_t sockcount, int *maxfd) {
unsigned int i;
char* errstring = NULL;
size_t sockpos = 0;
int nsock;
TRACE(("listensockets: %d to try\n", svr_opts.portcount))
for (i = 0; i < svr_opts.portcount; i++) {
TRACE(("listening on '%s:%s'", svr_opts.addresses[i], svr_opts.ports[i]))
nsock = dropbear_listen(svr_opts.addresses[i], svr_opts.ports[i], &sock[sockpos],
sockcount - sockpos,
&errstring, maxfd);
if (nsock < 0) {
dropbear_log(LOG_WARNING, "Failed listening on '%s': %s",
svr_opts.ports[i], errstring);
m_free(errstring);
continue;
}
sockpos += nsock;
}
return sockpos;
}