diff options
Diffstat (limited to 'crypto/openssh/serverloop.c')
-rw-r--r-- | crypto/openssh/serverloop.c | 1254 |
1 files changed, 1254 insertions, 0 deletions
diff --git a/crypto/openssh/serverloop.c b/crypto/openssh/serverloop.c new file mode 100644 index 0000000..8be01c5 --- /dev/null +++ b/crypto/openssh/serverloop.c @@ -0,0 +1,1254 @@ +/* $OpenBSD: serverloop.c,v 1.159 2009/05/28 16:50:16 andreas 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, 1) == -1) || + (fcntl(notify_pipe[1], F_SETFD, 1) == -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(); +} |