|
- /* $OpenBSD: serverloop.c,v 1.238 2024/04/30 02:14:10 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>
- #ifdef HAVE_POLL_H
- #include <poll.h>
- #endif
- #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 "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. */
-
- 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;
- }
-
- static void
- sigchld_handler(int sig)
- {
- child_terminated = 1;
- }
-
- 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_fr(r, "compose");
- } else {
- channel_request_start(ssh, channel_id,
- "keepalive@openssh.com", 1);
- }
- if ((r = sshpkt_send(ssh)) != 0)
- fatal_fr(r, "send");
- }
-
- /*
- * Sleep in ppoll() until we can do something.
- * 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, struct pollfd **pfdp,
- u_int *npfd_allocp, u_int *npfd_activep, sigset_t *sigsetp,
- int *conn_in_readyp, int *conn_out_readyp)
- {
- struct timespec timeout;
- char remote_id[512];
- int ret;
- int client_alive_scheduled = 0;
- u_int p;
- time_t now;
- static time_t last_client_time, unused_connection_expiry;
-
- *conn_in_readyp = *conn_out_readyp = 0;
-
- /* Prepare channel poll. First two pollfd entries are reserved */
- ptimeout_init(&timeout);
- channel_prepare_poll(ssh, pfdp, npfd_allocp, npfd_activep, 2, &timeout);
- now = monotime();
- if (*npfd_activep < 2)
- fatal_f("bad npfd %u", *npfd_activep); /* shouldn't happen */
- if (options.rekey_interval > 0 && !ssh_packet_is_rekeying(ssh)) {
- ptimeout_deadline_sec(&timeout,
- ssh_packet_get_rekey_timeout(ssh));
- }
-
- /*
- * If no channels are open and UnusedConnectionTimeout is set, then
- * start the clock to terminate the connection.
- */
- if (options.unused_connection_timeout != 0) {
- if (channel_still_open(ssh) || unused_connection_expiry == 0) {
- unused_connection_expiry = now +
- options.unused_connection_timeout;
- }
- ptimeout_deadline_monotime(&timeout, unused_connection_expiry);
- }
-
- /*
- * 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) {
- /* Time we last heard from the client OR sent a keepalive */
- if (last_client_time == 0)
- last_client_time = now;
- ptimeout_deadline_sec(&timeout, options.client_alive_interval);
- /* XXX ? deadline_monotime(last_client_time + alive_interval) */
- client_alive_scheduled = 1;
- }
-
- #if 0
- /* wrong: bad condition XXX */
- if (channel_not_very_much_buffered_data())
- #endif
- /* Monitor client connection on reserved pollfd entries */
- (*pfdp)[0].fd = connection_in;
- (*pfdp)[0].events = POLLIN;
- (*pfdp)[1].fd = connection_out;
- (*pfdp)[1].events = ssh_packet_have_data_to_write(ssh) ? POLLOUT : 0;
-
- /*
- * 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))
- ptimeout_deadline_ms(&timeout, 100);
-
- /* Wait for something to happen, or the timeout to expire. */
- ret = ppoll(*pfdp, *npfd_activep, ptimeout_get_tsp(&timeout), sigsetp);
-
- if (ret == -1) {
- for (p = 0; p < *npfd_activep; p++)
- (*pfdp)[p].revents = 0;
- if (errno != EINTR)
- fatal_f("ppoll: %.100s", strerror(errno));
- return;
- }
-
- *conn_in_readyp = (*pfdp)[0].revents != 0;
- *conn_out_readyp = (*pfdp)[1].revents != 0;
-
- now = monotime(); /* need to reset after ppoll() */
- /* ClientAliveInterval probing */
- if (client_alive_scheduled) {
- if (ret == 0 &&
- now >= last_client_time + options.client_alive_interval) {
- /* ppoll timed out and we're due to probe */
- client_alive_check(ssh);
- last_client_time = now;
- } else if (ret != 0 && *conn_in_readyp) {
- /* Data from peer; reset probe timer. */
- last_client_time = now;
- }
- }
-
- /* UnusedConnectionTimeout handling */
- if (unused_connection_expiry != 0 &&
- now > unused_connection_expiry && !channel_still_open(ssh)) {
- sshpkt_fmt_connection_id(ssh, remote_id, sizeof(remote_id));
- logit("terminating inactive connection from %s", remote_id);
- cleanup_exit(255);
- }
- }
-
- /*
- * Processes input from the client and the program. Input data is stored
- * in buffers and processed later.
- */
- static int
- process_input(struct ssh *ssh, int connection_in)
- {
- int r;
-
- if ((r = ssh_packet_process_read(ssh, connection_in)) == 0)
- return 0; /* success */
- if (r == SSH_ERR_SYSTEM_ERROR) {
- if (errno == EAGAIN || errno == EINTR || errno == EWOULDBLOCK)
- return 0;
- if (errno == EPIPE) {
- verbose("Connection closed by %.100s port %d",
- ssh_remote_ipaddr(ssh), ssh_remote_port(ssh));
- return -1;
- }
- verbose("Read error from remote host %s port %d: %s",
- ssh_remote_ipaddr(ssh), ssh_remote_port(ssh),
- strerror(errno));
- cleanup_exit(255);
- }
- return -1;
- }
-
- /*
- * Sends data from internal buffers to client program stdin.
- */
- static void
- process_output(struct ssh *ssh, int connection_out)
- {
- int r;
-
- /* Send any buffered packet data to the client. */
- 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;
- int status;
-
- 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;
- }
- }
-
- void
- server_loop2(struct ssh *ssh, Authctxt *authctxt)
- {
- struct pollfd *pfd = NULL;
- u_int npfd_alloc = 0, npfd_active = 0;
- int r, conn_in_ready, conn_out_ready;
- u_int connection_in, connection_out;
- sigset_t bsigset, osigset;
-
- debug("Entering interactive session for SSH2.");
-
- if (sigemptyset(&bsigset) == -1 || sigaddset(&bsigset, SIGCHLD) == -1)
- error_f("bsigset setup: %s", strerror(errno));
- 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);
- }
-
- 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);
-
- /*
- * Block SIGCHLD while we check for dead children, then pass
- * the old signal mask through to ppoll() so that it'll wake
- * up immediately if a child exits after we've called waitpid().
- */
- if (sigprocmask(SIG_BLOCK, &bsigset, &osigset) == -1)
- error_f("bsigset sigprocmask: %s", strerror(errno));
- collect_children(ssh);
- wait_until_can_do_something(ssh, connection_in, connection_out,
- &pfd, &npfd_alloc, &npfd_active, &osigset,
- &conn_in_ready, &conn_out_ready);
- if (sigprocmask(SIG_SETMASK, &osigset, NULL) == -1)
- error_f("osigset sigprocmask: %s", strerror(errno));
-
- if (received_sigterm) {
- logit("Exiting on signal %d", (int)received_sigterm);
- /* Clean up sessions, utmp, etc. */
- cleanup_exit(255);
- }
-
- channel_after_poll(ssh, pfd, npfd_active);
- if (conn_in_ready &&
- process_input(ssh, connection_in) < 0)
- break;
- /* A timeout may have triggered rekeying */
- if ((r = ssh_packet_check_rekey(ssh)) != 0)
- fatal_fr(r, "cannot start rekeying");
- if (conn_out_ready)
- process_output(ssh, connection_out);
- }
- collect_children(ssh);
- free(pfd);
-
- /* 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_f("invalid target port");
- *reason = SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED;
- goto out;
- }
- if (originator_port > 0xFFFF) {
- error_f("invalid originator port");
- *reason = SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED;
- goto out;
- }
-
- debug_f("originator %s port %u, target %s port %u",
- 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_f("no/invalid user");
-
- 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_f("invalid originator port");
- goto out;
- }
-
- debug_f("originator %s port %d, target %s",
- 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_f("invalid tun");
- 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_f("ctype %s rchan %u win %u max %u",
- 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_f("confirm %s", 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_f("failure %s", 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, success = 0;
- const u_char *blob;
- const char *sigalg, *kex_rsa_sigalg = NULL;
- u_char *sig = 0;
- size_t blen, slen;
-
- if ((resp = sshbuf_new()) == NULL || (sigbuf = sshbuf_new()) == NULL)
- fatal_f("sshbuf_new");
- if (sshkey_type_plain(sshkey_type_from_name(
- ssh->kex->hostkey_alg)) == KEY_RSA)
- kex_rsa_sigalg = 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_fr(r, "parse key");
- 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_f("unknown host %s key", 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_f("can't retrieve hostkey %d", 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).
- */
- sigalg = NULL;
- if (sshkey_type_plain(key->type) == KEY_RSA) {
- if (kex_rsa_sigalg != NULL)
- sigalg = kex_rsa_sigalg;
- else if (ssh->kex->flags & KEX_RSA_SHA2_512_SUPPORTED)
- sigalg = "rsa-sha2-512";
- else if (ssh->kex->flags & KEX_RSA_SHA2_256_SUPPORTED)
- sigalg = "rsa-sha2-256";
- }
- debug3_f("sign %s key (index %d) using sigalg %s",
- sshkey_type(key), ndx, sigalg == NULL ? "default" : sigalg);
- if ((r = sshbuf_put_cstring(sigbuf,
- "hostkeys-prove-00@openssh.com")) != 0 ||
- (r = sshbuf_put_stringb(sigbuf,
- ssh->kex->session_id)) != 0 ||
- (r = sshkey_puts(key, sigbuf)) != 0 ||
- (r = ssh->kex->sign(ssh, key_prv, key_pub, &sig, &slen,
- sshbuf_ptr(sigbuf), sshbuf_len(sigbuf), sigalg)) != 0 ||
- (r = sshbuf_put_string(resp, sig, slen)) != 0) {
- error_fr(r, "assemble signature");
- 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_f("no/invalid user");
-
- 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_f("rtype %s want_reply %d", 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_f("tcpip-forward listen %s port %u",
- 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_f("sshbuf_new");
- if (allocated_listen_port != 0 &&
- (r = sshbuf_put_u32(resp, allocated_listen_port)) != 0)
- fatal_fr(r, "sshbuf_put_u32");
- } 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_f("cancel-tcpip-forward addr %s port %d",
- 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_f("streamlocal-forward listen path %s",
- 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_f("cancel-streamlocal-forward path %s",
- 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_f("channel %d: no remote_id", 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);
- }
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