--- /dev/null
+/* $OpenBSD: serverloop.c,v 1.160 2011/05/15 08:09:01 djm Exp $ */
+/*
+ * Author: Tatu Ylonen <ylo@cs.hut.fi>
+ * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
+ * All rights reserved
+ * Server main loop for handling the interactive session.
+ *
+ * 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 support by Markus Friedl.
+ * Copyright (c) 2000, 2001 Markus Friedl. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "includes.h"
+
+#include <sys/types.h>
+#include <sys/param.h>
+#include <sys/wait.h>
+#include <sys/socket.h>
+#ifdef HAVE_SYS_TIME_H
+# include <sys/time.h>
+#endif
+
+#include <netinet/in.h>
+
+#include <errno.h>
+#include <fcntl.h>
+#include <pwd.h>
+#include <signal.h>
+#include <string.h>
+#include <termios.h>
+#include <unistd.h>
+#include <stdarg.h>
+
+#include "openbsd-compat/sys-queue.h"
+#include "xmalloc.h"
+#include "packet.h"
+#include "buffer.h"
+#include "log.h"
+#include "servconf.h"
+#include "canohost.h"
+#include "sshpty.h"
+#include "channels.h"
+#include "compat.h"
+#include "ssh1.h"
+#include "ssh2.h"
+#include "key.h"
+#include "cipher.h"
+#include "kex.h"
+#include "hostfile.h"
+#include "auth.h"
+#include "session.h"
+#include "dispatch.h"
+#include "auth-options.h"
+#include "serverloop.h"
+#include "misc.h"
+#include "roaming.h"
+
+extern ServerOptions options;
+
+/* XXX */
+extern Kex *xxx_kex;
+extern Authctxt *the_authctxt;
+extern int use_privsep;
+
+static Buffer stdin_buffer; /* Buffer for stdin data. */
+static Buffer stdout_buffer; /* Buffer for stdout data. */
+static Buffer stderr_buffer; /* Buffer for stderr data. */
+static int fdin; /* Descriptor for stdin (for writing) */
+static int fdout; /* Descriptor for stdout (for reading);
+ May be same number as fdin. */
+static int fderr; /* Descriptor for stderr. May be -1. */
+static long stdin_bytes = 0; /* Number of bytes written to stdin. */
+static long stdout_bytes = 0; /* Number of stdout bytes sent to client. */
+static long stderr_bytes = 0; /* Number of stderr bytes sent to client. */
+static long fdout_bytes = 0; /* Number of stdout bytes read from program. */
+static int stdin_eof = 0; /* EOF message received from client. */
+static int fdout_eof = 0; /* EOF encountered reading from fdout. */
+static int fderr_eof = 0; /* EOF encountered readung from fderr. */
+static int fdin_is_tty = 0; /* fdin points to a tty. */
+static int connection_in; /* Connection to client (input). */
+static int connection_out; /* Connection to client (output). */
+static int connection_closed = 0; /* Connection to client closed. */
+static u_int buffer_high; /* "Soft" max buffer size. */
+static int no_more_sessions = 0; /* Disallow further sessions. */
+
+/*
+ * This SIGCHLD kludge is used to detect when the child exits. The server
+ * will exit after that, as soon as forwarded connections have terminated.
+ */
+
+static volatile sig_atomic_t child_terminated = 0; /* The child has terminated. */
+
+/* Cleanup on signals (!use_privsep case only) */
+static volatile sig_atomic_t received_sigterm = 0;
+
+/* prototypes */
+static void server_init_dispatch(void);
+
+/*
+ * we write to this pipe if a SIGCHLD is caught in order to avoid
+ * the race between select() and child_terminated
+ */
+static int notify_pipe[2];
+static void
+notify_setup(void)
+{
+ if (pipe(notify_pipe) < 0) {
+ error("pipe(notify_pipe) failed %s", strerror(errno));
+ } else if ((fcntl(notify_pipe[0], F_SETFD, FD_CLOEXEC) == -1) ||
+ (fcntl(notify_pipe[1], F_SETFD, FD_CLOEXEC) == -1)) {
+ error("fcntl(notify_pipe, F_SETFD) failed %s", strerror(errno));
+ close(notify_pipe[0]);
+ close(notify_pipe[1]);
+ } else {
+ set_nonblock(notify_pipe[0]);
+ set_nonblock(notify_pipe[1]);
+ return;
+ }
+ notify_pipe[0] = -1; /* read end */
+ notify_pipe[1] = -1; /* write end */
+}
+static void
+notify_parent(void)
+{
+ if (notify_pipe[1] != -1)
+ write(notify_pipe[1], "", 1);
+}
+static void
+notify_prepare(fd_set *readset)
+{
+ if (notify_pipe[0] != -1)
+ FD_SET(notify_pipe[0], readset);
+}
+static void
+notify_done(fd_set *readset)
+{
+ char c;
+
+ if (notify_pipe[0] != -1 && FD_ISSET(notify_pipe[0], readset))
+ while (read(notify_pipe[0], &c, 1) != -1)
+ debug2("notify_done: reading");
+}
+
+/*ARGSUSED*/
+static void
+sigchld_handler(int sig)
+{
+ int save_errno = errno;
+ child_terminated = 1;
+#ifndef _UNICOS
+ mysignal(SIGCHLD, sigchld_handler);
+#endif
+ notify_parent();
+ errno = save_errno;
+}
+
+/*ARGSUSED*/
+static void
+sigterm_handler(int sig)
+{
+ received_sigterm = sig;
+}
+
+/*
+ * Make packets from buffered stderr data, and buffer it for sending
+ * to the client.
+ */
+static void
+make_packets_from_stderr_data(void)
+{
+ u_int len;
+
+ /* Send buffered stderr data to the client. */
+ while (buffer_len(&stderr_buffer) > 0 &&
+ packet_not_very_much_data_to_write()) {
+ len = buffer_len(&stderr_buffer);
+ if (packet_is_interactive()) {
+ if (len > 512)
+ len = 512;
+ } else {
+ /* Keep the packets at reasonable size. */
+ if (len > packet_get_maxsize())
+ len = packet_get_maxsize();
+ }
+ packet_start(SSH_SMSG_STDERR_DATA);
+ packet_put_string(buffer_ptr(&stderr_buffer), len);
+ packet_send();
+ buffer_consume(&stderr_buffer, len);
+ stderr_bytes += len;
+ }
+}
+
+/*
+ * Make packets from buffered stdout data, and buffer it for sending to the
+ * client.
+ */
+static void
+make_packets_from_stdout_data(void)
+{
+ u_int len;
+
+ /* Send buffered stdout data to the client. */
+ while (buffer_len(&stdout_buffer) > 0 &&
+ packet_not_very_much_data_to_write()) {
+ len = buffer_len(&stdout_buffer);
+ if (packet_is_interactive()) {
+ if (len > 512)
+ len = 512;
+ } else {
+ /* Keep the packets at reasonable size. */
+ if (len > packet_get_maxsize())
+ len = packet_get_maxsize();
+ }
+ packet_start(SSH_SMSG_STDOUT_DATA);
+ packet_put_string(buffer_ptr(&stdout_buffer), len);
+ packet_send();
+ buffer_consume(&stdout_buffer, len);
+ stdout_bytes += len;
+ }
+}
+
+static void
+client_alive_check(void)
+{
+ int channel_id;
+
+ /* timeout, check to see how many we have had */
+ if (packet_inc_alive_timeouts() > options.client_alive_count_max) {
+ logit("Timeout, client not responding.");
+ cleanup_exit(255);
+ }
+
+ /*
+ * send a bogus global/channel request with "wantreply",
+ * we should get back a failure
+ */
+ if ((channel_id = channel_find_open()) == -1) {
+ packet_start(SSH2_MSG_GLOBAL_REQUEST);
+ packet_put_cstring("keepalive@openssh.com");
+ packet_put_char(1); /* boolean: want reply */
+ } else {
+ channel_request_start(channel_id, "keepalive@openssh.com", 1);
+ }
+ packet_send();
+}
+
+/*
+ * Sleep in select() until we can do something. This will initialize the
+ * select masks. Upon return, the masks will indicate which descriptors
+ * have data or can accept data. Optionally, a maximum time can be specified
+ * for the duration of the wait (0 = infinite).
+ */
+static void
+wait_until_can_do_something(fd_set **readsetp, fd_set **writesetp, int *maxfdp,
+ u_int *nallocp, u_int max_time_milliseconds)
+{
+ struct timeval tv, *tvp;
+ int ret;
+ int client_alive_scheduled = 0;
+ int program_alive_scheduled = 0;
+
+ /*
+ * if using client_alive, set the max timeout accordingly,
+ * and indicate that this particular timeout was for client
+ * alive by setting the client_alive_scheduled flag.
+ *
+ * this could be randomized somewhat to make traffic
+ * analysis more difficult, but we're not doing it yet.
+ */
+ if (compat20 &&
+ max_time_milliseconds == 0 && options.client_alive_interval) {
+ client_alive_scheduled = 1;
+ max_time_milliseconds = options.client_alive_interval * 1000;
+ }
+
+ /* Allocate and update select() masks for channel descriptors. */
+ channel_prepare_select(readsetp, writesetp, maxfdp, nallocp, 0);
+
+ if (compat20) {
+#if 0
+ /* wrong: bad condition XXX */
+ if (channel_not_very_much_buffered_data())
+#endif
+ FD_SET(connection_in, *readsetp);
+ } else {
+ /*
+ * Read packets from the client unless we have too much
+ * buffered stdin or channel data.
+ */
+ if (buffer_len(&stdin_buffer) < buffer_high &&
+ channel_not_very_much_buffered_data())
+ FD_SET(connection_in, *readsetp);
+ /*
+ * If there is not too much data already buffered going to
+ * the client, try to get some more data from the program.
+ */
+ if (packet_not_very_much_data_to_write()) {
+ program_alive_scheduled = child_terminated;
+ if (!fdout_eof)
+ FD_SET(fdout, *readsetp);
+ if (!fderr_eof)
+ FD_SET(fderr, *readsetp);
+ }
+ /*
+ * If we have buffered data, try to write some of that data
+ * to the program.
+ */
+ if (fdin != -1 && buffer_len(&stdin_buffer) > 0)
+ FD_SET(fdin, *writesetp);
+ }
+ notify_prepare(*readsetp);
+
+ /*
+ * If we have buffered packet data going to the client, mark that
+ * descriptor.
+ */
+ if (packet_have_data_to_write())
+ FD_SET(connection_out, *writesetp);
+
+ /*
+ * If child has terminated and there is enough buffer space to read
+ * from it, then read as much as is available and exit.
+ */
+ if (child_terminated && packet_not_very_much_data_to_write())
+ if (max_time_milliseconds == 0 || client_alive_scheduled)
+ max_time_milliseconds = 100;
+
+ if (max_time_milliseconds == 0)
+ tvp = NULL;
+ else {
+ tv.tv_sec = max_time_milliseconds / 1000;
+ tv.tv_usec = 1000 * (max_time_milliseconds % 1000);
+ tvp = &tv;
+ }
+
+ /* Wait for something to happen, or the timeout to expire. */
+ ret = select((*maxfdp)+1, *readsetp, *writesetp, NULL, tvp);
+
+ if (ret == -1) {
+ memset(*readsetp, 0, *nallocp);
+ memset(*writesetp, 0, *nallocp);
+ if (errno != EINTR)
+ error("select: %.100s", strerror(errno));
+ } else {
+ if (ret == 0 && client_alive_scheduled)
+ client_alive_check();
+ if (!compat20 && program_alive_scheduled && fdin_is_tty) {
+ if (!fdout_eof)
+ FD_SET(fdout, *readsetp);
+ if (!fderr_eof)
+ FD_SET(fderr, *readsetp);
+ }
+ }
+
+ notify_done(*readsetp);
+}
+
+/*
+ * Processes input from the client and the program. Input data is stored
+ * in buffers and processed later.
+ */
+static void
+process_input(fd_set *readset)
+{
+ int len;
+ char buf[16384];
+
+ /* Read and buffer any input data from the client. */
+ if (FD_ISSET(connection_in, readset)) {
+ int cont = 0;
+ len = roaming_read(connection_in, buf, sizeof(buf), &cont);
+ if (len == 0) {
+ if (cont)
+ return;
+ verbose("Connection closed by %.100s",
+ get_remote_ipaddr());
+ connection_closed = 1;
+ if (compat20)
+ return;
+ cleanup_exit(255);
+ } else if (len < 0) {
+ if (errno != EINTR && errno != EAGAIN &&
+ errno != EWOULDBLOCK) {
+ verbose("Read error from remote host "
+ "%.100s: %.100s",
+ get_remote_ipaddr(), strerror(errno));
+ cleanup_exit(255);
+ }
+ } else {
+ /* Buffer any received data. */
+ packet_process_incoming(buf, len);
+ }
+ }
+ if (compat20)
+ return;
+
+ /* Read and buffer any available stdout data from the program. */
+ if (!fdout_eof && FD_ISSET(fdout, readset)) {
+ errno = 0;
+ len = read(fdout, buf, sizeof(buf));
+ if (len < 0 && (errno == EINTR || ((errno == EAGAIN ||
+ errno == EWOULDBLOCK) && !child_terminated))) {
+ /* do nothing */
+#ifndef PTY_ZEROREAD
+ } else if (len <= 0) {
+#else
+ } else if ((!isatty(fdout) && len <= 0) ||
+ (isatty(fdout) && (len < 0 || (len == 0 && errno != 0)))) {
+#endif
+ fdout_eof = 1;
+ } else {
+ buffer_append(&stdout_buffer, buf, len);
+ fdout_bytes += len;
+ }
+ }
+ /* Read and buffer any available stderr data from the program. */
+ if (!fderr_eof && FD_ISSET(fderr, readset)) {
+ errno = 0;
+ len = read(fderr, buf, sizeof(buf));
+ if (len < 0 && (errno == EINTR || ((errno == EAGAIN ||
+ errno == EWOULDBLOCK) && !child_terminated))) {
+ /* do nothing */
+#ifndef PTY_ZEROREAD
+ } else if (len <= 0) {
+#else
+ } else if ((!isatty(fderr) && len <= 0) ||
+ (isatty(fderr) && (len < 0 || (len == 0 && errno != 0)))) {
+#endif
+ fderr_eof = 1;
+ } else {
+ buffer_append(&stderr_buffer, buf, len);
+ }
+ }
+}
+
+/*
+ * Sends data from internal buffers to client program stdin.
+ */
+static void
+process_output(fd_set *writeset)
+{
+ struct termios tio;
+ u_char *data;
+ u_int dlen;
+ int len;
+
+ /* Write buffered data to program stdin. */
+ if (!compat20 && fdin != -1 && FD_ISSET(fdin, writeset)) {
+ data = buffer_ptr(&stdin_buffer);
+ dlen = buffer_len(&stdin_buffer);
+ len = write(fdin, data, dlen);
+ if (len < 0 &&
+ (errno == EINTR || errno == EAGAIN || errno == EWOULDBLOCK)) {
+ /* do nothing */
+ } else if (len <= 0) {
+ if (fdin != fdout)
+ close(fdin);
+ else
+ shutdown(fdin, SHUT_WR); /* We will no longer send. */
+ fdin = -1;
+ } else {
+ /* Successful write. */
+ if (fdin_is_tty && dlen >= 1 && data[0] != '\r' &&
+ tcgetattr(fdin, &tio) == 0 &&
+ !(tio.c_lflag & ECHO) && (tio.c_lflag & ICANON)) {
+ /*
+ * Simulate echo to reduce the impact of
+ * traffic analysis
+ */
+ packet_send_ignore(len);
+ packet_send();
+ }
+ /* Consume the data from the buffer. */
+ buffer_consume(&stdin_buffer, len);
+ /* Update the count of bytes written to the program. */
+ stdin_bytes += len;
+ }
+ }
+ /* Send any buffered packet data to the client. */
+ if (FD_ISSET(connection_out, writeset))
+ packet_write_poll();
+}
+
+/*
+ * Wait until all buffered output has been sent to the client.
+ * This is used when the program terminates.
+ */
+static void
+drain_output(void)
+{
+ /* Send any buffered stdout data to the client. */
+ if (buffer_len(&stdout_buffer) > 0) {
+ packet_start(SSH_SMSG_STDOUT_DATA);
+ packet_put_string(buffer_ptr(&stdout_buffer),
+ buffer_len(&stdout_buffer));
+ packet_send();
+ /* Update the count of sent bytes. */
+ stdout_bytes += buffer_len(&stdout_buffer);
+ }
+ /* Send any buffered stderr data to the client. */
+ if (buffer_len(&stderr_buffer) > 0) {
+ packet_start(SSH_SMSG_STDERR_DATA);
+ packet_put_string(buffer_ptr(&stderr_buffer),
+ buffer_len(&stderr_buffer));
+ packet_send();
+ /* Update the count of sent bytes. */
+ stderr_bytes += buffer_len(&stderr_buffer);
+ }
+ /* Wait until all buffered data has been written to the client. */
+ packet_write_wait();
+}
+
+static void
+process_buffered_input_packets(void)
+{
+ dispatch_run(DISPATCH_NONBLOCK, NULL, compat20 ? xxx_kex : NULL);
+}
+
+/*
+ * Performs the interactive session. This handles data transmission between
+ * the client and the program. Note that the notion of stdin, stdout, and
+ * stderr in this function is sort of reversed: this function writes to
+ * stdin (of the child program), and reads from stdout and stderr (of the
+ * child program).
+ */
+void
+server_loop(pid_t pid, int fdin_arg, int fdout_arg, int fderr_arg)
+{
+ fd_set *readset = NULL, *writeset = NULL;
+ int max_fd = 0;
+ u_int nalloc = 0;
+ int wait_status; /* Status returned by wait(). */
+ pid_t wait_pid; /* pid returned by wait(). */
+ int waiting_termination = 0; /* Have displayed waiting close message. */
+ u_int max_time_milliseconds;
+ u_int previous_stdout_buffer_bytes;
+ u_int stdout_buffer_bytes;
+ int type;
+
+ debug("Entering interactive session.");
+
+ /* Initialize the SIGCHLD kludge. */
+ child_terminated = 0;
+ mysignal(SIGCHLD, sigchld_handler);
+
+ if (!use_privsep) {
+ signal(SIGTERM, sigterm_handler);
+ signal(SIGINT, sigterm_handler);
+ signal(SIGQUIT, sigterm_handler);
+ }
+
+ /* Initialize our global variables. */
+ fdin = fdin_arg;
+ fdout = fdout_arg;
+ fderr = fderr_arg;
+
+ /* nonblocking IO */
+ set_nonblock(fdin);
+ set_nonblock(fdout);
+ /* we don't have stderr for interactive terminal sessions, see below */
+ if (fderr != -1)
+ set_nonblock(fderr);
+
+ if (!(datafellows & SSH_BUG_IGNOREMSG) && isatty(fdin))
+ fdin_is_tty = 1;
+
+ connection_in = packet_get_connection_in();
+ connection_out = packet_get_connection_out();
+
+ notify_setup();
+
+ previous_stdout_buffer_bytes = 0;
+
+ /* Set approximate I/O buffer size. */
+ if (packet_is_interactive())
+ buffer_high = 4096;
+ else
+ buffer_high = 64 * 1024;
+
+#if 0
+ /* Initialize max_fd to the maximum of the known file descriptors. */
+ max_fd = MAX(connection_in, connection_out);
+ max_fd = MAX(max_fd, fdin);
+ max_fd = MAX(max_fd, fdout);
+ if (fderr != -1)
+ max_fd = MAX(max_fd, fderr);
+#endif
+
+ /* Initialize Initialize buffers. */
+ buffer_init(&stdin_buffer);
+ buffer_init(&stdout_buffer);
+ buffer_init(&stderr_buffer);
+
+ /*
+ * If we have no separate fderr (which is the case when we have a pty
+ * - there we cannot make difference between data sent to stdout and
+ * stderr), indicate that we have seen an EOF from stderr. This way
+ * we don't need to check the descriptor everywhere.
+ */
+ if (fderr == -1)
+ fderr_eof = 1;
+
+ server_init_dispatch();
+
+ /* Main loop of the server for the interactive session mode. */
+ for (;;) {
+
+ /* Process buffered packets from the client. */
+ process_buffered_input_packets();
+
+ /*
+ * If we have received eof, and there is no more pending
+ * input data, cause a real eof by closing fdin.
+ */
+ if (stdin_eof && fdin != -1 && buffer_len(&stdin_buffer) == 0) {
+ if (fdin != fdout)
+ close(fdin);
+ else
+ shutdown(fdin, SHUT_WR); /* We will no longer send. */
+ fdin = -1;
+ }
+ /* Make packets from buffered stderr data to send to the client. */
+ make_packets_from_stderr_data();
+
+ /*
+ * Make packets from buffered stdout data to send to the
+ * client. If there is very little to send, this arranges to
+ * not send them now, but to wait a short while to see if we
+ * are getting more data. This is necessary, as some systems
+ * wake up readers from a pty after each separate character.
+ */
+ max_time_milliseconds = 0;
+ stdout_buffer_bytes = buffer_len(&stdout_buffer);
+ if (stdout_buffer_bytes != 0 && stdout_buffer_bytes < 256 &&
+ stdout_buffer_bytes != previous_stdout_buffer_bytes) {
+ /* try again after a while */
+ max_time_milliseconds = 10;
+ } else {
+ /* Send it now. */
+ make_packets_from_stdout_data();
+ }
+ previous_stdout_buffer_bytes = buffer_len(&stdout_buffer);
+
+ /* Send channel data to the client. */
+ if (packet_not_very_much_data_to_write())
+ channel_output_poll();
+
+ /*
+ * Bail out of the loop if the program has closed its output
+ * descriptors, and we have no more data to send to the
+ * client, and there is no pending buffered data.
+ */
+ if (fdout_eof && fderr_eof && !packet_have_data_to_write() &&
+ buffer_len(&stdout_buffer) == 0 && buffer_len(&stderr_buffer) == 0) {
+ if (!channel_still_open())
+ break;
+ if (!waiting_termination) {
+ const char *s = "Waiting for forwarded connections to terminate...\r\n";
+ char *cp;
+ waiting_termination = 1;
+ buffer_append(&stderr_buffer, s, strlen(s));
+
+ /* Display list of open channels. */
+ cp = channel_open_message();
+ buffer_append(&stderr_buffer, cp, strlen(cp));
+ xfree(cp);
+ }
+ }
+ max_fd = MAX(connection_in, connection_out);
+ max_fd = MAX(max_fd, fdin);
+ max_fd = MAX(max_fd, fdout);
+ max_fd = MAX(max_fd, fderr);
+ max_fd = MAX(max_fd, notify_pipe[0]);
+
+ /* Sleep in select() until we can do something. */
+ wait_until_can_do_something(&readset, &writeset, &max_fd,
+ &nalloc, max_time_milliseconds);
+
+ if (received_sigterm) {
+ logit("Exiting on signal %d", received_sigterm);
+ /* Clean up sessions, utmp, etc. */
+ cleanup_exit(255);
+ }
+
+ /* Process any channel events. */
+ channel_after_select(readset, writeset);
+
+ /* Process input from the client and from program stdout/stderr. */
+ process_input(readset);
+
+ /* Process output to the client and to program stdin. */
+ process_output(writeset);
+ }
+ if (readset)
+ xfree(readset);
+ if (writeset)
+ xfree(writeset);
+
+ /* Cleanup and termination code. */
+
+ /* Wait until all output has been sent to the client. */
+ drain_output();
+
+ debug("End of interactive session; stdin %ld, stdout (read %ld, sent %ld), stderr %ld bytes.",
+ stdin_bytes, fdout_bytes, stdout_bytes, stderr_bytes);
+
+ /* Free and clear the buffers. */
+ buffer_free(&stdin_buffer);
+ buffer_free(&stdout_buffer);
+ buffer_free(&stderr_buffer);
+
+ /* Close the file descriptors. */
+ if (fdout != -1)
+ close(fdout);
+ fdout = -1;
+ fdout_eof = 1;
+ if (fderr != -1)
+ close(fderr);
+ fderr = -1;
+ fderr_eof = 1;
+ if (fdin != -1)
+ close(fdin);
+ fdin = -1;
+
+ channel_free_all();
+
+ /* We no longer want our SIGCHLD handler to be called. */
+ mysignal(SIGCHLD, SIG_DFL);
+
+ while ((wait_pid = waitpid(-1, &wait_status, 0)) < 0)
+ if (errno != EINTR)
+ packet_disconnect("wait: %.100s", strerror(errno));
+ if (wait_pid != pid)
+ error("Strange, wait returned pid %ld, expected %ld",
+ (long)wait_pid, (long)pid);
+
+ /* Check if it exited normally. */
+ if (WIFEXITED(wait_status)) {
+ /* Yes, normal exit. Get exit status and send it to the client. */
+ debug("Command exited with status %d.", WEXITSTATUS(wait_status));
+ packet_start(SSH_SMSG_EXITSTATUS);
+ packet_put_int(WEXITSTATUS(wait_status));
+ packet_send();
+ packet_write_wait();
+
+ /*
+ * Wait for exit confirmation. Note that there might be
+ * other packets coming before it; however, the program has
+ * already died so we just ignore them. The client is
+ * supposed to respond with the confirmation when it receives
+ * the exit status.
+ */
+ do {
+ type = packet_read();
+ }
+ while (type != SSH_CMSG_EXIT_CONFIRMATION);
+
+ debug("Received exit confirmation.");
+ return;
+ }
+ /* Check if the program terminated due to a signal. */
+ if (WIFSIGNALED(wait_status))
+ packet_disconnect("Command terminated on signal %d.",
+ WTERMSIG(wait_status));
+
+ /* Some weird exit cause. Just exit. */
+ packet_disconnect("wait returned status %04x.", wait_status);
+ /* NOTREACHED */
+}
+
+static void
+collect_children(void)
+{
+ pid_t pid;
+ sigset_t oset, nset;
+ int status;
+
+ /* block SIGCHLD while we check for dead children */
+ sigemptyset(&nset);
+ sigaddset(&nset, SIGCHLD);
+ sigprocmask(SIG_BLOCK, &nset, &oset);
+ if (child_terminated) {
+ debug("Received SIGCHLD.");
+ while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
+ (pid < 0 && errno == EINTR))
+ if (pid > 0)
+ session_close_by_pid(pid, status);
+ child_terminated = 0;
+ }
+ sigprocmask(SIG_SETMASK, &oset, NULL);
+}
+
+void
+server_loop2(Authctxt *authctxt)
+{
+ fd_set *readset = NULL, *writeset = NULL;
+ int rekeying = 0, max_fd, nalloc = 0;
+
+ debug("Entering interactive session for SSH2.");
+
+ mysignal(SIGCHLD, sigchld_handler);
+ child_terminated = 0;
+ connection_in = packet_get_connection_in();
+ connection_out = packet_get_connection_out();
+
+ if (!use_privsep) {
+ signal(SIGTERM, sigterm_handler);
+ signal(SIGINT, sigterm_handler);
+ signal(SIGQUIT, sigterm_handler);
+ }
+
+ notify_setup();
+
+ max_fd = MAX(connection_in, connection_out);
+ max_fd = MAX(max_fd, notify_pipe[0]);
+
+ server_init_dispatch();
+
+ for (;;) {
+ process_buffered_input_packets();
+
+ rekeying = (xxx_kex != NULL && !xxx_kex->done);
+
+ if (!rekeying && packet_not_very_much_data_to_write())
+ channel_output_poll();
+ wait_until_can_do_something(&readset, &writeset, &max_fd,
+ &nalloc, 0);
+
+ if (received_sigterm) {
+ logit("Exiting on signal %d", received_sigterm);
+ /* Clean up sessions, utmp, etc. */
+ cleanup_exit(255);
+ }
+
+ collect_children();
+ if (!rekeying) {
+ channel_after_select(readset, writeset);
+ if (packet_need_rekeying()) {
+ debug("need rekeying");
+ xxx_kex->done = 0;
+ kex_send_kexinit(xxx_kex);
+ }
+ }
+ process_input(readset);
+ if (connection_closed)
+ break;
+ process_output(writeset);
+ }
+ collect_children();
+
+ if (readset)
+ xfree(readset);
+ if (writeset)
+ xfree(writeset);
+
+ /* free all channels, no more reads and writes */
+ channel_free_all();
+
+ /* free remaining sessions, e.g. remove wtmp entries */
+ session_destroy_all(NULL);
+}
+
+static void
+server_input_keep_alive(int type, u_int32_t seq, void *ctxt)
+{
+ debug("Got %d/%u for keepalive", type, seq);
+ /*
+ * reset timeout, since we got a sane answer from the client.
+ * even if this was generated by something other than
+ * the bogus CHANNEL_REQUEST we send for keepalives.
+ */
+ packet_set_alive_timeouts(0);
+}
+
+static void
+server_input_stdin_data(int type, u_int32_t seq, void *ctxt)
+{
+ char *data;
+ u_int data_len;
+
+ /* Stdin data from the client. Append it to the buffer. */
+ /* Ignore any data if the client has closed stdin. */
+ if (fdin == -1)
+ return;
+ data = packet_get_string(&data_len);
+ packet_check_eom();
+ buffer_append(&stdin_buffer, data, data_len);
+ memset(data, 0, data_len);
+ xfree(data);
+}
+
+static void
+server_input_eof(int type, u_int32_t seq, void *ctxt)
+{
+ /*
+ * Eof from the client. The stdin descriptor to the
+ * program will be closed when all buffered data has
+ * drained.
+ */
+ debug("EOF received for stdin.");
+ packet_check_eom();
+ stdin_eof = 1;
+}
+
+static void
+server_input_window_size(int type, u_int32_t seq, void *ctxt)
+{
+ u_int row = packet_get_int();
+ u_int col = packet_get_int();
+ u_int xpixel = packet_get_int();
+ u_int ypixel = packet_get_int();
+
+ debug("Window change received.");
+ packet_check_eom();
+ if (fdin != -1)
+ pty_change_window_size(fdin, row, col, xpixel, ypixel);
+}
+
+static Channel *
+server_request_direct_tcpip(void)
+{
+ Channel *c;
+ char *target, *originator;
+ u_short target_port, originator_port;
+
+ target = packet_get_string(NULL);
+ target_port = packet_get_int();
+ originator = packet_get_string(NULL);
+ originator_port = packet_get_int();
+ packet_check_eom();
+
+ debug("server_request_direct_tcpip: originator %s port %d, target %s "
+ "port %d", originator, originator_port, target, target_port);
+
+ /* XXX check permission */
+ c = channel_connect_to(target, target_port,
+ "direct-tcpip", "direct-tcpip");
+
+ xfree(originator);
+ xfree(target);
+
+ return c;
+}
+
+static Channel *
+server_request_tun(void)
+{
+ Channel *c = NULL;
+ int mode, tun;
+ int sock;
+
+ mode = packet_get_int();
+ switch (mode) {
+ case SSH_TUNMODE_POINTOPOINT:
+ case SSH_TUNMODE_ETHERNET:
+ break;
+ default:
+ packet_send_debug("Unsupported tunnel device mode.");
+ return NULL;
+ }
+ if ((options.permit_tun & mode) == 0) {
+ packet_send_debug("Server has rejected tunnel device "
+ "forwarding");
+ return NULL;
+ }
+
+ tun = packet_get_int();
+ if (forced_tun_device != -1) {
+ if (tun != SSH_TUNID_ANY && forced_tun_device != tun)
+ goto done;
+ tun = forced_tun_device;
+ }
+ sock = tun_open(tun, mode);
+ if (sock < 0)
+ goto done;
+ c = channel_new("tun", SSH_CHANNEL_OPEN, sock, sock, -1,
+ CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 0, "tun", 1);
+ c->datagram = 1;
+#if defined(SSH_TUN_FILTER)
+ if (mode == SSH_TUNMODE_POINTOPOINT)
+ channel_register_filter(c->self, sys_tun_infilter,
+ sys_tun_outfilter, NULL, NULL);
+#endif
+
+ done:
+ if (c == NULL)
+ packet_send_debug("Failed to open the tunnel device.");
+ return c;
+}
+
+static Channel *
+server_request_session(void)
+{
+ Channel *c;
+
+ debug("input_session_request");
+ packet_check_eom();
+
+ if (no_more_sessions) {
+ packet_disconnect("Possible attack: attempt to open a session "
+ "after additional sessions disabled");
+ }
+
+ /*
+ * A server session has no fd to read or write until a
+ * CHANNEL_REQUEST for a shell is made, so we set the type to
+ * SSH_CHANNEL_LARVAL. Additionally, a callback for handling all
+ * CHANNEL_REQUEST messages is registered.
+ */
+ c = channel_new("session", SSH_CHANNEL_LARVAL,
+ -1, -1, -1, /*window size*/0, CHAN_SES_PACKET_DEFAULT,
+ 0, "server-session", 1);
+ if (session_open(the_authctxt, c->self) != 1) {
+ debug("session open failed, free channel %d", c->self);
+ channel_free(c);
+ return NULL;
+ }
+ channel_register_cleanup(c->self, session_close_by_channel, 0);
+ return c;
+}
+
+static void
+server_input_channel_open(int type, u_int32_t seq, void *ctxt)
+{
+ Channel *c = NULL;
+ char *ctype;
+ int rchan;
+ u_int rmaxpack, rwindow, len;
+
+ ctype = packet_get_string(&len);
+ rchan = packet_get_int();
+ rwindow = packet_get_int();
+ rmaxpack = packet_get_int();
+
+ debug("server_input_channel_open: ctype %s rchan %d win %d max %d",
+ ctype, rchan, rwindow, rmaxpack);
+
+ if (strcmp(ctype, "session") == 0) {
+ c = server_request_session();
+ } else if (strcmp(ctype, "direct-tcpip") == 0) {
+ c = server_request_direct_tcpip();
+ } else if (strcmp(ctype, "tun@openssh.com") == 0) {
+ c = server_request_tun();
+ }
+ if (c != NULL) {
+ debug("server_input_channel_open: confirm %s", ctype);
+ c->remote_id = rchan;
+ c->remote_window = rwindow;
+ c->remote_maxpacket = rmaxpack;
+ if (c->type != SSH_CHANNEL_CONNECTING) {
+ packet_start(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION);
+ packet_put_int(c->remote_id);
+ packet_put_int(c->self);
+ packet_put_int(c->local_window);
+ packet_put_int(c->local_maxpacket);
+ packet_send();
+ }
+ } else {
+ debug("server_input_channel_open: failure %s", ctype);
+ packet_start(SSH2_MSG_CHANNEL_OPEN_FAILURE);
+ packet_put_int(rchan);
+ packet_put_int(SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED);
+ if (!(datafellows & SSH_BUG_OPENFAILURE)) {
+ packet_put_cstring("open failed");
+ packet_put_cstring("");
+ }
+ packet_send();
+ }
+ xfree(ctype);
+}
+
+static void
+server_input_global_request(int type, u_int32_t seq, void *ctxt)
+{
+ char *rtype;
+ int want_reply;
+ int success = 0, allocated_listen_port = 0;
+
+ rtype = packet_get_string(NULL);
+ want_reply = packet_get_char();
+ debug("server_input_global_request: rtype %s want_reply %d", rtype, want_reply);
+
+ /* -R style forwarding */
+ if (strcmp(rtype, "tcpip-forward") == 0) {
+ struct passwd *pw;
+ char *listen_address;
+ u_short listen_port;
+
+ pw = the_authctxt->pw;
+ if (pw == NULL || !the_authctxt->valid)
+ fatal("server_input_global_request: no/invalid user");
+ listen_address = packet_get_string(NULL);
+ listen_port = (u_short)packet_get_int();
+ debug("server_input_global_request: tcpip-forward listen %s port %d",
+ listen_address, listen_port);
+
+ /* check permissions */
+ if (!options.allow_tcp_forwarding ||
+ no_port_forwarding_flag ||
+ (!want_reply && listen_port == 0)
+#ifndef NO_IPPORT_RESERVED_CONCEPT
+ || (listen_port != 0 && listen_port < IPPORT_RESERVED &&
+ pw->pw_uid != 0)
+#endif
+ ) {
+ success = 0;
+ packet_send_debug("Server has disabled port forwarding.");
+ } else {
+ /* Start listening on the port */
+ success = channel_setup_remote_fwd_listener(
+ listen_address, listen_port,
+ &allocated_listen_port, options.gateway_ports);
+ }
+ xfree(listen_address);
+ } else if (strcmp(rtype, "cancel-tcpip-forward") == 0) {
+ char *cancel_address;
+ u_short cancel_port;
+
+ cancel_address = packet_get_string(NULL);
+ cancel_port = (u_short)packet_get_int();
+ debug("%s: cancel-tcpip-forward addr %s port %d", __func__,
+ cancel_address, cancel_port);
+
+ success = channel_cancel_rport_listener(cancel_address,
+ cancel_port);
+ xfree(cancel_address);
+ } else if (strcmp(rtype, "no-more-sessions@openssh.com") == 0) {
+ no_more_sessions = 1;
+ success = 1;
+ }
+ if (want_reply) {
+ packet_start(success ?
+ SSH2_MSG_REQUEST_SUCCESS : SSH2_MSG_REQUEST_FAILURE);
+ if (success && allocated_listen_port > 0)
+ packet_put_int(allocated_listen_port);
+ packet_send();
+ packet_write_wait();
+ }
+ xfree(rtype);
+}
+
+static void
+server_input_channel_req(int type, u_int32_t seq, void *ctxt)
+{
+ Channel *c;
+ int id, reply, success = 0;
+ char *rtype;
+
+ id = packet_get_int();
+ rtype = packet_get_string(NULL);
+ reply = packet_get_char();
+
+ debug("server_input_channel_req: channel %d request %s reply %d",
+ id, rtype, reply);
+
+ if ((c = channel_lookup(id)) == NULL)
+ packet_disconnect("server_input_channel_req: "
+ "unknown channel %d", id);
+ if (!strcmp(rtype, "eow@openssh.com")) {
+ packet_check_eom();
+ chan_rcvd_eow(c);
+ } else if ((c->type == SSH_CHANNEL_LARVAL ||
+ c->type == SSH_CHANNEL_OPEN) && strcmp(c->ctype, "session") == 0)
+ success = session_input_channel_req(c, rtype);
+ if (reply) {
+ packet_start(success ?
+ SSH2_MSG_CHANNEL_SUCCESS : SSH2_MSG_CHANNEL_FAILURE);
+ packet_put_int(c->remote_id);
+ packet_send();
+ }
+ xfree(rtype);
+}
+
+static void
+server_init_dispatch_20(void)
+{
+ debug("server_init_dispatch_20");
+ dispatch_init(&dispatch_protocol_error);
+ dispatch_set(SSH2_MSG_CHANNEL_CLOSE, &channel_input_oclose);
+ dispatch_set(SSH2_MSG_CHANNEL_DATA, &channel_input_data);
+ dispatch_set(SSH2_MSG_CHANNEL_EOF, &channel_input_ieof);
+ dispatch_set(SSH2_MSG_CHANNEL_EXTENDED_DATA, &channel_input_extended_data);
+ dispatch_set(SSH2_MSG_CHANNEL_OPEN, &server_input_channel_open);
+ dispatch_set(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation);
+ dispatch_set(SSH2_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure);
+ dispatch_set(SSH2_MSG_CHANNEL_REQUEST, &server_input_channel_req);
+ dispatch_set(SSH2_MSG_CHANNEL_WINDOW_ADJUST, &channel_input_window_adjust);
+ dispatch_set(SSH2_MSG_GLOBAL_REQUEST, &server_input_global_request);
+ /* client_alive */
+ dispatch_set(SSH2_MSG_CHANNEL_SUCCESS, &server_input_keep_alive);
+ dispatch_set(SSH2_MSG_CHANNEL_FAILURE, &server_input_keep_alive);
+ dispatch_set(SSH2_MSG_REQUEST_SUCCESS, &server_input_keep_alive);
+ dispatch_set(SSH2_MSG_REQUEST_FAILURE, &server_input_keep_alive);
+ /* rekeying */
+ dispatch_set(SSH2_MSG_KEXINIT, &kex_input_kexinit);
+}
+static void
+server_init_dispatch_13(void)
+{
+ debug("server_init_dispatch_13");
+ dispatch_init(NULL);
+ dispatch_set(SSH_CMSG_EOF, &server_input_eof);
+ dispatch_set(SSH_CMSG_STDIN_DATA, &server_input_stdin_data);
+ dispatch_set(SSH_CMSG_WINDOW_SIZE, &server_input_window_size);
+ dispatch_set(SSH_MSG_CHANNEL_CLOSE, &channel_input_close);
+ dispatch_set(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION, &channel_input_close_confirmation);
+ dispatch_set(SSH_MSG_CHANNEL_DATA, &channel_input_data);
+ dispatch_set(SSH_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation);
+ dispatch_set(SSH_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure);
+ dispatch_set(SSH_MSG_PORT_OPEN, &channel_input_port_open);
+}
+static void
+server_init_dispatch_15(void)
+{
+ server_init_dispatch_13();
+ debug("server_init_dispatch_15");
+ dispatch_set(SSH_MSG_CHANNEL_CLOSE, &channel_input_ieof);
+ dispatch_set(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION, &channel_input_oclose);
+}
+static void
+server_init_dispatch(void)
+{
+ if (compat20)
+ server_init_dispatch_20();
+ else if (compat13)
+ server_init_dispatch_13();
+ else
+ server_init_dispatch_15();
+}
projects / openssh.git / blobdiff