summaryrefslogtreecommitdiffstats
path: root/serverloop.c
diff options
context:
space:
mode:
Diffstat (limited to '')
-rw-r--r--serverloop.c984
1 files changed, 984 insertions, 0 deletions
diff --git a/serverloop.c b/serverloop.c
new file mode 100644
index 0000000..48d936d
--- /dev/null
+++ b/serverloop.c
@@ -0,0 +1,984 @@
+/* $OpenBSD: serverloop.c,v 1.223 2020/07/03 06:29:57 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/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 <limits.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 "sshbuf.h"
+#include "log.h"
+#include "misc.h"
+#include "servconf.h"
+#include "canohost.h"
+#include "sshpty.h"
+#include "channels.h"
+#include "compat.h"
+#include "ssh2.h"
+#include "sshkey.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 "ssherr.h"
+
+extern ServerOptions options;
+
+/* XXX */
+extern Authctxt *the_authctxt;
+extern struct sshauthopt *auth_opts;
+extern int use_privsep;
+
+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(struct ssh *);
+
+/* requested tunnel forwarding interface(s), shared with session.c */
+char *tun_fwd_ifnames = NULL;
+
+/* returns 1 if bind to specified port by specified user is permitted */
+static int
+bind_permitted(int port, uid_t uid)
+{
+ if (use_privsep)
+ return 1; /* allow system to decide */
+ if (port < IPPORT_RESERVED && uid != 0)
+ return 0;
+ return 1;
+}
+
+/*
+ * 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) == -1) {
+ 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)
+ (void)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("%s: reading", __func__);
+}
+
+/*ARGSUSED*/
+static void
+sigchld_handler(int sig)
+{
+ int save_errno = errno;
+ child_terminated = 1;
+ notify_parent();
+ errno = save_errno;
+}
+
+/*ARGSUSED*/
+static void
+sigterm_handler(int sig)
+{
+ received_sigterm = sig;
+}
+
+static void
+client_alive_check(struct ssh *ssh)
+{
+ char remote_id[512];
+ int r, channel_id;
+
+ /* timeout, check to see how many we have had */
+ if (options.client_alive_count_max > 0 &&
+ ssh_packet_inc_alive_timeouts(ssh) >
+ options.client_alive_count_max) {
+ sshpkt_fmt_connection_id(ssh, remote_id, sizeof(remote_id));
+ logit("Timeout, client not responding from %s", remote_id);
+ cleanup_exit(255);
+ }
+
+ /*
+ * send a bogus global/channel request with "wantreply",
+ * we should get back a failure
+ */
+ if ((channel_id = channel_find_open(ssh)) == -1) {
+ if ((r = sshpkt_start(ssh, SSH2_MSG_GLOBAL_REQUEST)) != 0 ||
+ (r = sshpkt_put_cstring(ssh, "keepalive@openssh.com"))
+ != 0 ||
+ (r = sshpkt_put_u8(ssh, 1)) != 0) /* boolean: want reply */
+ fatal("%s: %s", __func__, ssh_err(r));
+ } else {
+ channel_request_start(ssh, channel_id,
+ "keepalive@openssh.com", 1);
+ }
+ if ((r = sshpkt_send(ssh)) != 0)
+ fatal("%s: %s", __func__, ssh_err(r));
+}
+
+/*
+ * 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(struct ssh *ssh,
+ int connection_in, int connection_out,
+ fd_set **readsetp, fd_set **writesetp, int *maxfdp,
+ u_int *nallocp, u_int64_t max_time_ms)
+{
+ struct timeval tv, *tvp;
+ int ret;
+ time_t minwait_secs = 0;
+ int client_alive_scheduled = 0;
+ /* time we last heard from the client OR sent a keepalive */
+ static time_t last_client_time;
+
+ /* Allocate and update select() masks for channel descriptors. */
+ channel_prepare_select(ssh, readsetp, writesetp, maxfdp,
+ nallocp, &minwait_secs);
+
+ /* XXX need proper deadline system for rekey/client alive */
+ if (minwait_secs != 0)
+ max_time_ms = MINIMUM(max_time_ms, (u_int)minwait_secs * 1000);
+
+ /*
+ * 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 (options.client_alive_interval) {
+ uint64_t keepalive_ms =
+ (uint64_t)options.client_alive_interval * 1000;
+
+ if (max_time_ms == 0 || max_time_ms > keepalive_ms) {
+ max_time_ms = keepalive_ms;
+ client_alive_scheduled = 1;
+ }
+ if (last_client_time == 0)
+ last_client_time = monotime();
+ }
+
+#if 0
+ /* wrong: bad condition XXX */
+ if (channel_not_very_much_buffered_data())
+#endif
+ FD_SET(connection_in, *readsetp);
+ notify_prepare(*readsetp);
+
+ /*
+ * If we have buffered packet data going to the client, mark that
+ * descriptor.
+ */
+ if (ssh_packet_have_data_to_write(ssh))
+ 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 && ssh_packet_not_very_much_data_to_write(ssh))
+ if (max_time_ms == 0 || client_alive_scheduled)
+ max_time_ms = 100;
+
+ if (max_time_ms == 0)
+ tvp = NULL;
+ else {
+ tv.tv_sec = max_time_ms / 1000;
+ tv.tv_usec = 1000 * (max_time_ms % 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 (client_alive_scheduled) {
+ time_t now = monotime();
+
+ /*
+ * If the select timed out, or returned for some other reason
+ * but we haven't heard from the client in time, send keepalive.
+ */
+ if (ret == 0 || (last_client_time != 0 && last_client_time +
+ options.client_alive_interval <= now)) {
+ client_alive_check(ssh);
+ last_client_time = now;
+ } else if (FD_ISSET(connection_in, *readsetp)) {
+ last_client_time = now;
+ }
+ }
+
+ notify_done(*readsetp);
+}
+
+/*
+ * Processes input from the client and the program. Input data is stored
+ * in buffers and processed later.
+ */
+static int
+process_input(struct ssh *ssh, fd_set *readset, int connection_in)
+{
+ int r, len;
+ char buf[16384];
+
+ /* Read and buffer any input data from the client. */
+ if (FD_ISSET(connection_in, readset)) {
+ len = read(connection_in, buf, sizeof(buf));
+ if (len == 0) {
+ verbose("Connection closed by %.100s port %d",
+ ssh_remote_ipaddr(ssh), ssh_remote_port(ssh));
+ return -1;
+ } else if (len == -1) {
+ if (errno != EINTR && errno != EAGAIN &&
+ errno != EWOULDBLOCK) {
+ verbose("Read error from remote host "
+ "%.100s port %d: %.100s",
+ ssh_remote_ipaddr(ssh),
+ ssh_remote_port(ssh), strerror(errno));
+ cleanup_exit(255);
+ }
+ } else {
+ /* Buffer any received data. */
+ if ((r = ssh_packet_process_incoming(ssh, buf, len))
+ != 0)
+ fatal("%s: ssh_packet_process_incoming: %s",
+ __func__, ssh_err(r));
+ }
+ }
+ return 0;
+}
+
+/*
+ * Sends data from internal buffers to client program stdin.
+ */
+static void
+process_output(struct ssh *ssh, fd_set *writeset, int connection_out)
+{
+ int r;
+
+ /* Send any buffered packet data to the client. */
+ if (FD_ISSET(connection_out, writeset)) {
+ if ((r = ssh_packet_write_poll(ssh)) != 0) {
+ sshpkt_fatal(ssh, r, "%s: ssh_packet_write_poll",
+ __func__);
+ }
+ }
+}
+
+static void
+process_buffered_input_packets(struct ssh *ssh)
+{
+ ssh_dispatch_run_fatal(ssh, DISPATCH_NONBLOCK, NULL);
+}
+
+static void
+collect_children(struct ssh *ssh)
+{
+ 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 == -1 && errno == EINTR))
+ if (pid > 0)
+ session_close_by_pid(ssh, pid, status);
+ child_terminated = 0;
+ }
+ sigprocmask(SIG_SETMASK, &oset, NULL);
+}
+
+void
+server_loop2(struct ssh *ssh, Authctxt *authctxt)
+{
+ fd_set *readset = NULL, *writeset = NULL;
+ int max_fd;
+ u_int nalloc = 0, connection_in, connection_out;
+ u_int64_t rekey_timeout_ms = 0;
+
+ debug("Entering interactive session for SSH2.");
+
+ ssh_signal(SIGCHLD, sigchld_handler);
+ child_terminated = 0;
+ connection_in = ssh_packet_get_connection_in(ssh);
+ connection_out = ssh_packet_get_connection_out(ssh);
+
+ if (!use_privsep) {
+ ssh_signal(SIGTERM, sigterm_handler);
+ ssh_signal(SIGINT, sigterm_handler);
+ ssh_signal(SIGQUIT, sigterm_handler);
+ }
+
+ notify_setup();
+
+ max_fd = MAXIMUM(connection_in, connection_out);
+ max_fd = MAXIMUM(max_fd, notify_pipe[0]);
+
+ server_init_dispatch(ssh);
+
+ for (;;) {
+ process_buffered_input_packets(ssh);
+
+ if (!ssh_packet_is_rekeying(ssh) &&
+ ssh_packet_not_very_much_data_to_write(ssh))
+ channel_output_poll(ssh);
+ if (options.rekey_interval > 0 &&
+ !ssh_packet_is_rekeying(ssh)) {
+ rekey_timeout_ms = ssh_packet_get_rekey_timeout(ssh) *
+ 1000;
+ } else {
+ rekey_timeout_ms = 0;
+ }
+
+ wait_until_can_do_something(ssh, connection_in, connection_out,
+ &readset, &writeset, &max_fd, &nalloc, rekey_timeout_ms);
+
+ if (received_sigterm) {
+ logit("Exiting on signal %d", (int)received_sigterm);
+ /* Clean up sessions, utmp, etc. */
+ cleanup_exit(255);
+ }
+
+ collect_children(ssh);
+ if (!ssh_packet_is_rekeying(ssh))
+ channel_after_select(ssh, readset, writeset);
+ if (process_input(ssh, readset, connection_in) < 0)
+ break;
+ process_output(ssh, writeset, connection_out);
+ }
+ collect_children(ssh);
+
+ free(readset);
+ free(writeset);
+
+ /* free all channels, no more reads and writes */
+ channel_free_all(ssh);
+
+ /* free remaining sessions, e.g. remove wtmp entries */
+ session_destroy_all(ssh, NULL);
+}
+
+static int
+server_input_keep_alive(int type, u_int32_t seq, struct ssh *ssh)
+{
+ 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.
+ */
+ ssh_packet_set_alive_timeouts(ssh, 0);
+ return 0;
+}
+
+static Channel *
+server_request_direct_tcpip(struct ssh *ssh, int *reason, const char **errmsg)
+{
+ Channel *c = NULL;
+ char *target = NULL, *originator = NULL;
+ u_int target_port = 0, originator_port = 0;
+ int r;
+
+ if ((r = sshpkt_get_cstring(ssh, &target, NULL)) != 0 ||
+ (r = sshpkt_get_u32(ssh, &target_port)) != 0 ||
+ (r = sshpkt_get_cstring(ssh, &originator, NULL)) != 0 ||
+ (r = sshpkt_get_u32(ssh, &originator_port)) != 0 ||
+ (r = sshpkt_get_end(ssh)) != 0)
+ sshpkt_fatal(ssh, r, "%s: parse packet", __func__);
+ if (target_port > 0xFFFF) {
+ error("%s: invalid target port", __func__);
+ *reason = SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED;
+ goto out;
+ }
+ if (originator_port > 0xFFFF) {
+ error("%s: invalid originator port", __func__);
+ *reason = SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED;
+ goto out;
+ }
+
+ debug("%s: originator %s port %u, target %s port %u", __func__,
+ originator, originator_port, target, target_port);
+
+ /* XXX fine grained permissions */
+ if ((options.allow_tcp_forwarding & FORWARD_LOCAL) != 0 &&
+ auth_opts->permit_port_forwarding_flag &&
+ !options.disable_forwarding) {
+ c = channel_connect_to_port(ssh, target, target_port,
+ "direct-tcpip", "direct-tcpip", reason, errmsg);
+ } else {
+ logit("refused local port forward: "
+ "originator %s port %d, target %s port %d",
+ originator, originator_port, target, target_port);
+ if (reason != NULL)
+ *reason = SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED;
+ }
+
+ out:
+ free(originator);
+ free(target);
+ return c;
+}
+
+static Channel *
+server_request_direct_streamlocal(struct ssh *ssh)
+{
+ Channel *c = NULL;
+ char *target = NULL, *originator = NULL;
+ u_int originator_port = 0;
+ struct passwd *pw = the_authctxt->pw;
+ int r;
+
+ if (pw == NULL || !the_authctxt->valid)
+ fatal("%s: no/invalid user", __func__);
+
+ if ((r = sshpkt_get_cstring(ssh, &target, NULL)) != 0 ||
+ (r = sshpkt_get_cstring(ssh, &originator, NULL)) != 0 ||
+ (r = sshpkt_get_u32(ssh, &originator_port)) != 0 ||
+ (r = sshpkt_get_end(ssh)) != 0)
+ sshpkt_fatal(ssh, r, "%s: parse packet", __func__);
+ if (originator_port > 0xFFFF) {
+ error("%s: invalid originator port", __func__);
+ goto out;
+ }
+
+ debug("%s: originator %s port %d, target %s", __func__,
+ originator, originator_port, target);
+
+ /* XXX fine grained permissions */
+ if ((options.allow_streamlocal_forwarding & FORWARD_LOCAL) != 0 &&
+ auth_opts->permit_port_forwarding_flag &&
+ !options.disable_forwarding && (pw->pw_uid == 0 || use_privsep)) {
+ c = channel_connect_to_path(ssh, target,
+ "direct-streamlocal@openssh.com", "direct-streamlocal");
+ } else {
+ logit("refused streamlocal port forward: "
+ "originator %s port %d, target %s",
+ originator, originator_port, target);
+ }
+
+out:
+ free(originator);
+ free(target);
+ return c;
+}
+
+static Channel *
+server_request_tun(struct ssh *ssh)
+{
+ Channel *c = NULL;
+ u_int mode, tun;
+ int r, sock;
+ char *tmp, *ifname = NULL;
+
+ if ((r = sshpkt_get_u32(ssh, &mode)) != 0)
+ sshpkt_fatal(ssh, r, "%s: parse mode", __func__);
+ switch (mode) {
+ case SSH_TUNMODE_POINTOPOINT:
+ case SSH_TUNMODE_ETHERNET:
+ break;
+ default:
+ ssh_packet_send_debug(ssh, "Unsupported tunnel device mode.");
+ return NULL;
+ }
+ if ((options.permit_tun & mode) == 0) {
+ ssh_packet_send_debug(ssh, "Server has rejected tunnel device "
+ "forwarding");
+ return NULL;
+ }
+
+ if ((r = sshpkt_get_u32(ssh, &tun)) != 0)
+ sshpkt_fatal(ssh, r, "%s: parse device", __func__);
+ if (tun > INT_MAX) {
+ debug("%s: invalid tun", __func__);
+ goto done;
+ }
+ if (auth_opts->force_tun_device != -1) {
+ if (tun != SSH_TUNID_ANY &&
+ auth_opts->force_tun_device != (int)tun)
+ goto done;
+ tun = auth_opts->force_tun_device;
+ }
+ sock = tun_open(tun, mode, &ifname);
+ if (sock < 0)
+ goto done;
+ debug("Tunnel forwarding using interface %s", ifname);
+
+ c = channel_new(ssh, "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(ssh, c->self, sys_tun_infilter,
+ sys_tun_outfilter, NULL, NULL);
+#endif
+
+ /*
+ * Update the list of names exposed to the session
+ * XXX remove these if the tunnels are closed (won't matter
+ * much if they are already in the environment though)
+ */
+ tmp = tun_fwd_ifnames;
+ xasprintf(&tun_fwd_ifnames, "%s%s%s",
+ tun_fwd_ifnames == NULL ? "" : tun_fwd_ifnames,
+ tun_fwd_ifnames == NULL ? "" : ",",
+ ifname);
+ free(tmp);
+ free(ifname);
+
+ done:
+ if (c == NULL)
+ ssh_packet_send_debug(ssh, "Failed to open the tunnel device.");
+ return c;
+}
+
+static Channel *
+server_request_session(struct ssh *ssh)
+{
+ Channel *c;
+ int r;
+
+ debug("input_session_request");
+ if ((r = sshpkt_get_end(ssh)) != 0)
+ sshpkt_fatal(ssh, r, "%s: parse packet", __func__);
+
+ if (no_more_sessions) {
+ ssh_packet_disconnect(ssh, "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(ssh, "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(ssh, c);
+ return NULL;
+ }
+ channel_register_cleanup(ssh, c->self, session_close_by_channel, 0);
+ return c;
+}
+
+static int
+server_input_channel_open(int type, u_int32_t seq, struct ssh *ssh)
+{
+ Channel *c = NULL;
+ char *ctype = NULL;
+ const char *errmsg = NULL;
+ int r, reason = SSH2_OPEN_CONNECT_FAILED;
+ u_int rchan = 0, rmaxpack = 0, rwindow = 0;
+
+ if ((r = sshpkt_get_cstring(ssh, &ctype, NULL)) != 0 ||
+ (r = sshpkt_get_u32(ssh, &rchan)) != 0 ||
+ (r = sshpkt_get_u32(ssh, &rwindow)) != 0 ||
+ (r = sshpkt_get_u32(ssh, &rmaxpack)) != 0)
+ sshpkt_fatal(ssh, r, "%s: parse packet", __func__);
+ debug("%s: ctype %s rchan %u win %u max %u", __func__,
+ ctype, rchan, rwindow, rmaxpack);
+
+ if (strcmp(ctype, "session") == 0) {
+ c = server_request_session(ssh);
+ } else if (strcmp(ctype, "direct-tcpip") == 0) {
+ c = server_request_direct_tcpip(ssh, &reason, &errmsg);
+ } else if (strcmp(ctype, "direct-streamlocal@openssh.com") == 0) {
+ c = server_request_direct_streamlocal(ssh);
+ } else if (strcmp(ctype, "tun@openssh.com") == 0) {
+ c = server_request_tun(ssh);
+ }
+ if (c != NULL) {
+ debug("%s: confirm %s", __func__, ctype);
+ c->remote_id = rchan;
+ c->have_remote_id = 1;
+ c->remote_window = rwindow;
+ c->remote_maxpacket = rmaxpack;
+ if (c->type != SSH_CHANNEL_CONNECTING) {
+ if ((r = sshpkt_start(ssh, SSH2_MSG_CHANNEL_OPEN_CONFIRMATION)) != 0 ||
+ (r = sshpkt_put_u32(ssh, c->remote_id)) != 0 ||
+ (r = sshpkt_put_u32(ssh, c->self)) != 0 ||
+ (r = sshpkt_put_u32(ssh, c->local_window)) != 0 ||
+ (r = sshpkt_put_u32(ssh, c->local_maxpacket)) != 0 ||
+ (r = sshpkt_send(ssh)) != 0) {
+ sshpkt_fatal(ssh, r,
+ "%s: send open confirm", __func__);
+ }
+ }
+ } else {
+ debug("%s: failure %s", __func__, ctype);
+ if ((r = sshpkt_start(ssh, SSH2_MSG_CHANNEL_OPEN_FAILURE)) != 0 ||
+ (r = sshpkt_put_u32(ssh, rchan)) != 0 ||
+ (r = sshpkt_put_u32(ssh, reason)) != 0 ||
+ (r = sshpkt_put_cstring(ssh, errmsg ? errmsg : "open failed")) != 0 ||
+ (r = sshpkt_put_cstring(ssh, "")) != 0 ||
+ (r = sshpkt_send(ssh)) != 0) {
+ sshpkt_fatal(ssh, r,
+ "%s: send open failure", __func__);
+ }
+ }
+ free(ctype);
+ return 0;
+}
+
+static int
+server_input_hostkeys_prove(struct ssh *ssh, struct sshbuf **respp)
+{
+ struct sshbuf *resp = NULL;
+ struct sshbuf *sigbuf = NULL;
+ struct sshkey *key = NULL, *key_pub = NULL, *key_prv = NULL;
+ int r, ndx, kexsigtype, use_kexsigtype, success = 0;
+ const u_char *blob;
+ u_char *sig = 0;
+ size_t blen, slen;
+
+ if ((resp = sshbuf_new()) == NULL || (sigbuf = sshbuf_new()) == NULL)
+ fatal("%s: sshbuf_new", __func__);
+
+ kexsigtype = sshkey_type_plain(
+ sshkey_type_from_name(ssh->kex->hostkey_alg));
+ while (ssh_packet_remaining(ssh) > 0) {
+ sshkey_free(key);
+ key = NULL;
+ if ((r = sshpkt_get_string_direct(ssh, &blob, &blen)) != 0 ||
+ (r = sshkey_from_blob(blob, blen, &key)) != 0) {
+ error("%s: couldn't parse key: %s",
+ __func__, ssh_err(r));
+ goto out;
+ }
+ /*
+ * Better check that this is actually one of our hostkeys
+ * before attempting to sign anything with it.
+ */
+ if ((ndx = ssh->kex->host_key_index(key, 1, ssh)) == -1) {
+ error("%s: unknown host %s key",
+ __func__, sshkey_type(key));
+ goto out;
+ }
+ /*
+ * XXX refactor: make kex->sign just use an index rather
+ * than passing in public and private keys
+ */
+ if ((key_prv = get_hostkey_by_index(ndx)) == NULL &&
+ (key_pub = get_hostkey_public_by_index(ndx, ssh)) == NULL) {
+ error("%s: can't retrieve hostkey %d", __func__, ndx);
+ goto out;
+ }
+ sshbuf_reset(sigbuf);
+ free(sig);
+ sig = NULL;
+ /*
+ * For RSA keys, prefer to use the signature type negotiated
+ * during KEX to the default (SHA1).
+ */
+ use_kexsigtype = kexsigtype == KEY_RSA &&
+ sshkey_type_plain(key->type) == KEY_RSA;
+ if ((r = sshbuf_put_cstring(sigbuf,
+ "hostkeys-prove-00@openssh.com")) != 0 ||
+ (r = sshbuf_put_string(sigbuf,
+ ssh->kex->session_id, ssh->kex->session_id_len)) != 0 ||
+ (r = sshkey_puts(key, sigbuf)) != 0 ||
+ (r = ssh->kex->sign(ssh, key_prv, key_pub, &sig, &slen,
+ sshbuf_ptr(sigbuf), sshbuf_len(sigbuf),
+ use_kexsigtype ? ssh->kex->hostkey_alg : NULL)) != 0 ||
+ (r = sshbuf_put_string(resp, sig, slen)) != 0) {
+ error("%s: couldn't prepare signature: %s",
+ __func__, ssh_err(r));
+ goto out;
+ }
+ }
+ /* Success */
+ *respp = resp;
+ resp = NULL; /* don't free it */
+ success = 1;
+ out:
+ free(sig);
+ sshbuf_free(resp);
+ sshbuf_free(sigbuf);
+ sshkey_free(key);
+ return success;
+}
+
+static int
+server_input_global_request(int type, u_int32_t seq, struct ssh *ssh)
+{
+ char *rtype = NULL;
+ u_char want_reply = 0;
+ int r, success = 0, allocated_listen_port = 0;
+ u_int port = 0;
+ struct sshbuf *resp = NULL;
+ struct passwd *pw = the_authctxt->pw;
+ struct Forward fwd;
+
+ memset(&fwd, 0, sizeof(fwd));
+ if (pw == NULL || !the_authctxt->valid)
+ fatal("%s: no/invalid user", __func__);
+
+ if ((r = sshpkt_get_cstring(ssh, &rtype, NULL)) != 0 ||
+ (r = sshpkt_get_u8(ssh, &want_reply)) != 0)
+ sshpkt_fatal(ssh, r, "%s: parse packet", __func__);
+ debug("%s: rtype %s want_reply %d", __func__, rtype, want_reply);
+
+ /* -R style forwarding */
+ if (strcmp(rtype, "tcpip-forward") == 0) {
+ if ((r = sshpkt_get_cstring(ssh, &fwd.listen_host, NULL)) != 0 ||
+ (r = sshpkt_get_u32(ssh, &port)) != 0)
+ sshpkt_fatal(ssh, r, "%s: parse tcpip-forward", __func__);
+ debug("%s: tcpip-forward listen %s port %u", __func__,
+ fwd.listen_host, port);
+ if (port <= INT_MAX)
+ fwd.listen_port = (int)port;
+ /* check permissions */
+ if (port > INT_MAX ||
+ (options.allow_tcp_forwarding & FORWARD_REMOTE) == 0 ||
+ !auth_opts->permit_port_forwarding_flag ||
+ options.disable_forwarding ||
+ (!want_reply && fwd.listen_port == 0) ||
+ (fwd.listen_port != 0 &&
+ !bind_permitted(fwd.listen_port, pw->pw_uid))) {
+ success = 0;
+ ssh_packet_send_debug(ssh, "Server has disabled port forwarding.");
+ } else {
+ /* Start listening on the port */
+ success = channel_setup_remote_fwd_listener(ssh, &fwd,
+ &allocated_listen_port, &options.fwd_opts);
+ }
+ if ((resp = sshbuf_new()) == NULL)
+ fatal("%s: sshbuf_new", __func__);
+ if (allocated_listen_port != 0 &&
+ (r = sshbuf_put_u32(resp, allocated_listen_port)) != 0)
+ fatal("%s: sshbuf_put_u32: %s", __func__, ssh_err(r));
+ } else if (strcmp(rtype, "cancel-tcpip-forward") == 0) {
+ if ((r = sshpkt_get_cstring(ssh, &fwd.listen_host, NULL)) != 0 ||
+ (r = sshpkt_get_u32(ssh, &port)) != 0)
+ sshpkt_fatal(ssh, r, "%s: parse cancel-tcpip-forward", __func__);
+
+ debug("%s: cancel-tcpip-forward addr %s port %d", __func__,
+ fwd.listen_host, port);
+ if (port <= INT_MAX) {
+ fwd.listen_port = (int)port;
+ success = channel_cancel_rport_listener(ssh, &fwd);
+ }
+ } else if (strcmp(rtype, "streamlocal-forward@openssh.com") == 0) {
+ if ((r = sshpkt_get_cstring(ssh, &fwd.listen_path, NULL)) != 0)
+ sshpkt_fatal(ssh, r, "%s: parse streamlocal-forward@openssh.com", __func__);
+ debug("%s: streamlocal-forward listen path %s", __func__,
+ fwd.listen_path);
+
+ /* check permissions */
+ if ((options.allow_streamlocal_forwarding & FORWARD_REMOTE) == 0
+ || !auth_opts->permit_port_forwarding_flag ||
+ options.disable_forwarding ||
+ (pw->pw_uid != 0 && !use_privsep)) {
+ success = 0;
+ ssh_packet_send_debug(ssh, "Server has disabled "
+ "streamlocal forwarding.");
+ } else {
+ /* Start listening on the socket */
+ success = channel_setup_remote_fwd_listener(ssh,
+ &fwd, NULL, &options.fwd_opts);
+ }
+ } else if (strcmp(rtype, "cancel-streamlocal-forward@openssh.com") == 0) {
+ if ((r = sshpkt_get_cstring(ssh, &fwd.listen_path, NULL)) != 0)
+ sshpkt_fatal(ssh, r, "%s: parse cancel-streamlocal-forward@openssh.com", __func__);
+ debug("%s: cancel-streamlocal-forward path %s", __func__,
+ fwd.listen_path);
+
+ success = channel_cancel_rport_listener(ssh, &fwd);
+ } else if (strcmp(rtype, "no-more-sessions@openssh.com") == 0) {
+ no_more_sessions = 1;
+ success = 1;
+ } else if (strcmp(rtype, "hostkeys-prove-00@openssh.com") == 0) {
+ success = server_input_hostkeys_prove(ssh, &resp);
+ }
+ /* XXX sshpkt_get_end() */
+ if (want_reply) {
+ if ((r = sshpkt_start(ssh, success ?
+ SSH2_MSG_REQUEST_SUCCESS : SSH2_MSG_REQUEST_FAILURE)) != 0 ||
+ (success && resp != NULL && (r = sshpkt_putb(ssh, resp)) != 0) ||
+ (r = sshpkt_send(ssh)) != 0 ||
+ (r = ssh_packet_write_wait(ssh)) != 0)
+ sshpkt_fatal(ssh, r, "%s: send reply", __func__);
+ }
+ free(fwd.listen_host);
+ free(fwd.listen_path);
+ free(rtype);
+ sshbuf_free(resp);
+ return 0;
+}
+
+static int
+server_input_channel_req(int type, u_int32_t seq, struct ssh *ssh)
+{
+ Channel *c;
+ int r, success = 0;
+ char *rtype = NULL;
+ u_char want_reply = 0;
+ u_int id = 0;
+
+ if ((r = sshpkt_get_u32(ssh, &id)) != 0 ||
+ (r = sshpkt_get_cstring(ssh, &rtype, NULL)) != 0 ||
+ (r = sshpkt_get_u8(ssh, &want_reply)) != 0)
+ sshpkt_fatal(ssh, r, "%s: parse packet", __func__);
+
+ debug("server_input_channel_req: channel %u request %s reply %d",
+ id, rtype, want_reply);
+
+ if (id >= INT_MAX || (c = channel_lookup(ssh, (int)id)) == NULL) {
+ ssh_packet_disconnect(ssh, "%s: unknown channel %d",
+ __func__, id);
+ }
+ if (!strcmp(rtype, "eow@openssh.com")) {
+ if ((r = sshpkt_get_end(ssh)) != 0)
+ sshpkt_fatal(ssh, r, "%s: parse packet", __func__);
+ chan_rcvd_eow(ssh, c);
+ } else if ((c->type == SSH_CHANNEL_LARVAL ||
+ c->type == SSH_CHANNEL_OPEN) && strcmp(c->ctype, "session") == 0)
+ success = session_input_channel_req(ssh, c, rtype);
+ if (want_reply && !(c->flags & CHAN_CLOSE_SENT)) {
+ if (!c->have_remote_id)
+ fatal("%s: channel %d: no remote_id",
+ __func__, c->self);
+ if ((r = sshpkt_start(ssh, success ?
+ SSH2_MSG_CHANNEL_SUCCESS : SSH2_MSG_CHANNEL_FAILURE)) != 0 ||
+ (r = sshpkt_put_u32(ssh, c->remote_id)) != 0 ||
+ (r = sshpkt_send(ssh)) != 0)
+ sshpkt_fatal(ssh, r, "%s: send reply", __func__);
+ }
+ free(rtype);
+ return 0;
+}
+
+static void
+server_init_dispatch(struct ssh *ssh)
+{
+ debug("server_init_dispatch");
+ ssh_dispatch_init(ssh, &dispatch_protocol_error);
+ ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_CLOSE, &channel_input_oclose);
+ ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_DATA, &channel_input_data);
+ ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_EOF, &channel_input_ieof);
+ ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_EXTENDED_DATA, &channel_input_extended_data);
+ ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_OPEN, &server_input_channel_open);
+ ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation);
+ ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure);
+ ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_REQUEST, &server_input_channel_req);
+ ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_WINDOW_ADJUST, &channel_input_window_adjust);
+ ssh_dispatch_set(ssh, SSH2_MSG_GLOBAL_REQUEST, &server_input_global_request);
+ /* client_alive */
+ ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_SUCCESS, &server_input_keep_alive);
+ ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_FAILURE, &server_input_keep_alive);
+ ssh_dispatch_set(ssh, SSH2_MSG_REQUEST_SUCCESS, &server_input_keep_alive);
+ ssh_dispatch_set(ssh, SSH2_MSG_REQUEST_FAILURE, &server_input_keep_alive);
+ /* rekeying */
+ ssh_dispatch_set(ssh, SSH2_MSG_KEXINIT, &kex_input_kexinit);
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-07-11 05:16:26 +0000