/* $NetBSD: session.c,v 1.24.2.2 2020/04/13 07:45:20 martin Exp $ */
/* $OpenBSD: session.c,v 1.318 2020/01/23 07:10:22 dtucker Exp $ */
/*
* Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
* All rights reserved
*
* 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"
__RCSID("$NetBSD: session.c,v 1.24.2.2 2020/04/13 07:45:20 martin Exp $");
#include <sys/types.h>
#include <sys/wait.h>
#include <sys/un.h>
#include <sys/stat.h>
#include <sys/socket.h>
#include <sys/queue.h>
#include <ctype.h>
#include <errno.h>
#include <fcntl.h>
#include <grp.h>
#include <login_cap.h>
#include <netdb.h>
#include <paths.h>
#include <pwd.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdarg.h>
#include <unistd.h>
#include <limits.h>
#include "xmalloc.h"
#include "ssh.h"
#include "ssh2.h"
#include "sshpty.h"
#include "packet.h"
#include "sshbuf.h"
#include "ssherr.h"
#include "match.h"
#include "uidswap.h"
#include "compat.h"
#include "channels.h"
#include "sshkey.h"
#include "cipher.h"
#include "kex.h"
#include "hostfile.h"
#include "auth.h"
#include "auth-options.h"
#include "authfd.h"
#include "pathnames.h"
#include "log.h"
#include "misc.h"
#include "servconf.h"
#include "sshlogin.h"
#include "serverloop.h"
#include "canohost.h"
#include "session.h"
#ifdef GSSAPI
#include "ssh-gss.h"
#endif
#include "monitor_wrap.h"
#include "sftp.h"
#include "atomicio.h"
#ifdef KRB5
#include <krb5/kafs.h>
#endif
#define IS_INTERNAL_SFTP(c) \
(!strncmp(c, INTERNAL_SFTP_NAME, sizeof(INTERNAL_SFTP_NAME) - 1) && \
(c[sizeof(INTERNAL_SFTP_NAME) - 1] == '\0' || \
c[sizeof(INTERNAL_SFTP_NAME) - 1] == ' ' || \
c[sizeof(INTERNAL_SFTP_NAME) - 1] == '\t'))
/* func */
Session *session_new(void);
void session_set_fds(struct ssh *, Session *, int, int, int, int, int);
void session_pty_cleanup(Session *);
void session_proctitle(Session *);
int session_setup_x11fwd(struct ssh *, Session *);
int do_exec_pty(struct ssh *, Session *, const char *);
int do_exec_no_pty(struct ssh *, Session *, const char *);
int do_exec(struct ssh *, Session *, const char *);
void do_login(struct ssh *, Session *, const char *);
__dead void do_child(struct ssh *, Session *, const char *);
void do_motd(void);
int check_quietlogin(Session *, const char *);
static void do_authenticated2(struct ssh *, Authctxt *);
static int session_pty_req(struct ssh *, Session *);
/* import */
extern ServerOptions options;
extern char *__progname;
extern int debug_flag;
extern u_int utmp_len;
extern int startup_pipe;
extern void destroy_sensitive_data(void);
extern struct sshbuf *loginmsg;
extern struct sshauthopt *auth_opts;
extern char *tun_fwd_ifnames; /* serverloop.c */
/* original command from peer. */
const char *original_command = NULL;
/* data */
static int sessions_first_unused = -1;
static int sessions_nalloc = 0;
static Session *sessions = NULL;
#define SUBSYSTEM_NONE 0
#define SUBSYSTEM_EXT 1
#define SUBSYSTEM_INT_SFTP 2
#define SUBSYSTEM_INT_SFTP_ERROR 3
#ifdef HAVE_LOGIN_CAP
login_cap_t *lc;
#endif
static int is_child = 0;
static int in_chroot = 0;
/* File containing userauth info, if ExposeAuthInfo set */
static char *auth_info_file = NULL;
/* Name and directory of socket for authentication agent forwarding. */
static char *auth_sock_name = NULL;
static char *auth_sock_dir = NULL;
/* removes the agent forwarding socket */
static void
auth_sock_cleanup_proc(struct passwd *pw)
{
if (auth_sock_name != NULL) {
temporarily_use_uid(pw);
unlink(auth_sock_name);
rmdir(auth_sock_dir);
auth_sock_name = NULL;
restore_uid();
}
}
static int
auth_input_request_forwarding(struct ssh *ssh, struct passwd * pw)
{
Channel *nc;
int sock = -1;
if (auth_sock_name != NULL) {
error("authentication forwarding requested twice.");
return 0;
}
/* Temporarily drop privileged uid for mkdir/bind. */
temporarily_use_uid(pw);
/* Allocate a buffer for the socket name, and format the name. */
auth_sock_dir = xstrdup("/tmp/ssh-XXXXXXXXXX");
/* Create private directory for socket */
if (mkdtemp(auth_sock_dir) == NULL) {
ssh_packet_send_debug(ssh, "Agent forwarding disabled: "
"mkdtemp() failed: %.100s", strerror(errno));
restore_uid();
free(auth_sock_dir);
auth_sock_dir = NULL;
goto authsock_err;
}
xasprintf(&auth_sock_name, "%s/agent.%ld",
auth_sock_dir, (long) getpid());
/* Start a Unix listener on auth_sock_name. */
sock = unix_listener(auth_sock_name, SSH_LISTEN_BACKLOG, 0);
/* Restore the privileged uid. */
restore_uid();
/* Check for socket/bind/listen failure. */
if (sock < 0)
goto authsock_err;
/* Allocate a channel for the authentication agent socket. */
/* this shouldn't matter if its hpn or not - cjr */
nc = channel_new(ssh, "auth socket",
SSH_CHANNEL_AUTH_SOCKET, sock, sock, -1,
CHAN_X11_WINDOW_DEFAULT, CHAN_X11_PACKET_DEFAULT,
0, "auth socket", 1);
nc->path = xstrdup(auth_sock_name);
return 1;
authsock_err:
free(auth_sock_name);
if (auth_sock_dir != NULL) {
temporarily_use_uid(pw);
rmdir(auth_sock_dir);
restore_uid();
free(auth_sock_dir);
}
if (sock != -1)
close(sock);
auth_sock_name = NULL;
auth_sock_dir = NULL;
return 0;
}
static void
display_loginmsg(void)
{
int r;
if (sshbuf_len(loginmsg) == 0)
return;
if ((r = sshbuf_put_u8(loginmsg, 0)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
printf("%s", (const char *)sshbuf_ptr(loginmsg));
sshbuf_reset(loginmsg);
}
static void
prepare_auth_info_file(struct passwd *pw, struct sshbuf *info)
{
int fd = -1, success = 0;
if (!options.expose_userauth_info || info == NULL)
return;
temporarily_use_uid(pw);
auth_info_file = xstrdup("/tmp/sshauth.XXXXXXXXXXXXXXX");
if ((fd = mkstemp(auth_info_file)) == -1) {
error("%s: mkstemp: %s", __func__, strerror(errno));
goto out;
}
if (atomicio(vwrite, fd, sshbuf_mutable_ptr(info),
sshbuf_len(info)) != sshbuf_len(info)) {
error("%s: write: %s", __func__, strerror(errno));
goto out;
}
if (close(fd) != 0) {
error("%s: close: %s", __func__, strerror(errno));
goto out;
}
success = 1;
out:
if (!success) {
if (fd != -1)
close(fd);
free(auth_info_file);
auth_info_file = NULL;
}
restore_uid();
}
static void
set_fwdpermit_from_authopts(struct ssh *ssh, const struct sshauthopt *opts)
{
char *tmp, *cp, *host;
int port;
size_t i;
if ((options.allow_tcp_forwarding & FORWARD_LOCAL) != 0) {
channel_clear_permission(ssh, FORWARD_USER, FORWARD_LOCAL);
for (i = 0; i < auth_opts->npermitopen; i++) {
tmp = cp = xstrdup(auth_opts->permitopen[i]);
/* This shouldn't fail as it has already been checked */
if ((host = hpdelim(&cp)) == NULL)
fatal("%s: internal error: hpdelim", __func__);
host = cleanhostname(host);
if (cp == NULL || (port = permitopen_port(cp)) < 0)
fatal("%s: internal error: permitopen port",
__func__);
channel_add_permission(ssh,
FORWARD_USER, FORWARD_LOCAL, host, port);
free(tmp);
}
}
if ((options.allow_tcp_forwarding & FORWARD_REMOTE) != 0) {
channel_clear_permission(ssh, FORWARD_USER, FORWARD_REMOTE);
for (i = 0; i < auth_opts->npermitlisten; i++) {
tmp = cp = xstrdup(auth_opts->permitlisten[i]);
/* This shouldn't fail as it has already been checked */
if ((host = hpdelim(&cp)) == NULL)
fatal("%s: internal error: hpdelim", __func__);
host = cleanhostname(host);
if (cp == NULL || (port = permitopen_port(cp)) < 0)
fatal("%s: internal error: permitlisten port",
__func__);
channel_add_permission(ssh,
FORWARD_USER, FORWARD_REMOTE, host, port);
free(tmp);
}
}
}
void
do_authenticated(struct ssh *ssh, Authctxt *authctxt)
{
setproctitle("%s", authctxt->pw->pw_name);
auth_log_authopts("active", auth_opts, 0);
/* setup the channel layer */
/* XXX - streamlocal? */
set_fwdpermit_from_authopts(ssh, auth_opts);
if (!auth_opts->permit_port_forwarding_flag ||
options.disable_forwarding) {
channel_disable_admin(ssh, FORWARD_LOCAL);
channel_disable_admin(ssh, FORWARD_REMOTE);
} else {
if ((options.allow_tcp_forwarding & FORWARD_LOCAL) == 0)
channel_disable_admin(ssh, FORWARD_LOCAL);
else
channel_permit_all(ssh, FORWARD_LOCAL);
if ((options.allow_tcp_forwarding & FORWARD_REMOTE) == 0)
channel_disable_admin(ssh, FORWARD_REMOTE);
else
channel_permit_all(ssh, FORWARD_REMOTE);
}
auth_debug_send(ssh);
prepare_auth_info_file(authctxt->pw, authctxt->session_info);
do_authenticated2(ssh, authctxt);
do_cleanup(ssh, authctxt);
}
/* Check untrusted xauth strings for metacharacters */
static int
xauth_valid_string(const char *s)
{
size_t i;
for (i = 0; s[i] != '\0'; i++) {
if (!isalnum((u_char)s[i]) &&
s[i] != '.' && s[i] != ':' && s[i] != '/' &&
s[i] != '-' && s[i] != '_')
return 0;
}
return 1;
}
#define USE_PIPES 1
/*
* This is called to fork and execute a command when we have no tty. This
* will call do_child from the child, and server_loop from the parent after
* setting up file descriptors and such.
*/
int
do_exec_no_pty(struct ssh *ssh, Session *s, const char *command)
{
pid_t pid;
#ifdef USE_PIPES
int pin[2], pout[2], perr[2];
if (s == NULL)
fatal("do_exec_no_pty: no session");
/* Allocate pipes for communicating with the program. */
if (pipe(pin) == -1) {
error("%s: pipe in: %.100s", __func__, strerror(errno));
return -1;
}
if (pipe(pout) == -1) {
error("%s: pipe out: %.100s", __func__, strerror(errno));
close(pin[0]);
close(pin[1]);
return -1;
}
if (pipe(perr) == -1) {
error("%s: pipe err: %.100s", __func__,
strerror(errno));
close(pin[0]);
close(pin[1]);
close(pout[0]);
close(pout[1]);
return -1;
}
#else
int inout[2], err[2];
if (s == NULL)
fatal("do_exec_no_pty: no session");
/* Uses socket pairs to communicate with the program. */
if (socketpair(AF_UNIX, SOCK_STREAM, 0, inout) == -1) {
error("%s: socketpair #1: %.100s", __func__, strerror(errno));
return -1;
}
if (socketpair(AF_UNIX, SOCK_STREAM, 0, err) == -1) {
error("%s: socketpair #2: %.100s", __func__,
strerror(errno));
close(inout[0]);
close(inout[1]);
return -1;
}
#endif
session_proctitle(s);
#ifdef notdef
#if defined(USE_PAM)
if (options.use_pam && !use_privsep)
do_pam_setcred(1);
#endif /* USE_PAM */
#endif
/* Fork the child. */
switch ((pid = fork())) {
case -1:
error("%s: fork: %.100s", __func__, strerror(errno));
#ifdef USE_PIPES
close(pin[0]);
close(pin[1]);
close(pout[0]);
close(pout[1]);
close(perr[0]);
close(perr[1]);
#else
close(inout[0]);
close(inout[1]);
close(err[0]);
close(err[1]);
#endif
return -1;
case 0:
is_child = 1;
/*
* Create a new session and process group since the 4.4BSD
* setlogin() affects the entire process group.
*/
if (setsid() == -1)
error("setsid failed: %.100s", strerror(errno));
#ifdef USE_PIPES
/*
* Redirect stdin. We close the parent side of the socket
* pair, and make the child side the standard input.
*/
close(pin[1]);
if (dup2(pin[0], 0) == -1)
perror("dup2 stdin");
close(pin[0]);
/* Redirect stdout. */
close(pout[0]);
if (dup2(pout[1], 1) == -1)
perror("dup2 stdout");
close(pout[1]);
/* Redirect stderr. */
close(perr[0]);
if (dup2(perr[1], 2) == -1)
perror("dup2 stderr");
close(perr[1]);
#else
/*
* Redirect stdin, stdout, and stderr. Stdin and stdout will
* use the same socket, as some programs (particularly rdist)
* seem to depend on it.
*/
close(inout[1]);
close(err[1]);
if (dup2(inout[0], 0) == -1) /* stdin */
perror("dup2 stdin");
if (dup2(inout[0], 1) == -1) /* stdout (same as stdin) */
perror("dup2 stdout");
close(inout[0]);
if (dup2(err[0], 2) == -1) /* stderr */
perror("dup2 stderr");
close(err[0]);
#endif
/* Do processing for the child (exec command etc). */
do_child(ssh, s, command);
/* NOTREACHED */
default:
break;
}
s->pid = pid;
/* Set interactive/non-interactive mode. */
ssh_packet_set_interactive(ssh, s->display != NULL,
options.ip_qos_interactive, options.ip_qos_bulk);
#ifdef USE_PIPES
/* We are the parent. Close the child sides of the pipes. */
close(pin[0]);
close(pout[1]);
close(perr[1]);
session_set_fds(ssh, s, pin[1], pout[0], perr[0],
s->is_subsystem, 0);
#else
/* We are the parent. Close the child sides of the socket pairs. */
close(inout[0]);
close(err[0]);
/*
* Enter the interactive session. Note: server_loop must be able to
* handle the case that fdin and fdout are the same.
*/
session_set_fds(ssh, s, inout[1], inout[1], err[1],
s->is_subsystem, 0);
#endif
return 0;
}
/*
* This is called to fork and execute a command when we have a tty. This
* will call do_child from the child, and server_loop from the parent after
* setting up file descriptors, controlling tty, updating wtmp, utmp,
* lastlog, and other such operations.
*/
int
do_exec_pty(struct ssh *ssh, Session *s, const char *command)
{
int fdout, ptyfd, ttyfd, ptymaster;
pid_t pid;
if (s == NULL)
fatal("do_exec_pty: no session");
ptyfd = s->ptyfd;
ttyfd = s->ttyfd;
#if defined(USE_PAM)
if (options.use_pam) {
if (!use_privsep)
do_pam_setcred(1);
}
#endif
/*
* Create another descriptor of the pty master side for use as the
* standard input. We could use the original descriptor, but this
* simplifies code in server_loop. The descriptor is bidirectional.
* Do this before forking (and cleanup in the child) so as to
* detect and gracefully fail out-of-fd conditions.
*/
if ((fdout = dup(ptyfd)) == -1) {
error("%s: dup #1: %s", __func__, strerror(errno));
close(ttyfd);
close(ptyfd);
return -1;
}
/* we keep a reference to the pty master */
if ((ptymaster = dup(ptyfd)) == -1) {
error("%s: dup #2: %s", __func__, strerror(errno));
close(ttyfd);
close(ptyfd);
close(fdout);
return -1;
}
/* Fork the child. */
switch ((pid = fork())) {
case -1:
error("%s: fork: %.100s", __func__, strerror(errno));
close(fdout);
close(ptymaster);
close(ttyfd);
close(ptyfd);
return -1;
case 0:
is_child = 1;
close(fdout);
close(ptymaster);
/* Close the master side of the pseudo tty. */
close(ptyfd);
/* Make the pseudo tty our controlling tty. */
pty_make_controlling_tty(&ttyfd, s->tty);
/* Redirect stdin/stdout/stderr from the pseudo tty. */
if (dup2(ttyfd, 0) == -1)
error("dup2 stdin: %s", strerror(errno));
if (dup2(ttyfd, 1) == -1)
error("dup2 stdout: %s", strerror(errno));
if (dup2(ttyfd, 2) == -1)
error("dup2 stderr: %s", strerror(errno));
/* Close the extra descriptor for the pseudo tty. */
close(ttyfd);
/* record login, etc. similar to login(1) */
do_login(ssh, s, command);
/*
* Do common processing for the child, such as execing
* the command.
*/
do_child(ssh, s, command);
/* NOTREACHED */
default:
break;
}
s->pid = pid;
/* Parent. Close the slave side of the pseudo tty. */
close(ttyfd);
/* Enter interactive session. */
s->ptymaster = ptymaster;
ssh_packet_set_interactive(ssh, 1,
options.ip_qos_interactive, options.ip_qos_bulk);
session_set_fds(ssh, s, ptyfd, fdout, -1, 1, 1);
return 0;
}
/*
* This is called to fork and execute a command. If another command is
* to be forced, execute that instead.
*/
int
do_exec(struct ssh *ssh, Session *s, const char *command)
{
int ret;
const char *forced = NULL, *tty = NULL;
char session_type[1024];
if (options.adm_forced_command) {
original_command = command;
command = options.adm_forced_command;
forced = "(config)";
} else if (auth_opts->force_command != NULL) {
original_command = command;
command = auth_opts->force_command;
forced = "(key-option)";
}
s->forced = 0;
if (forced != NULL) {
s->forced = 1;
if (IS_INTERNAL_SFTP(command)) {
s->is_subsystem = s->is_subsystem ?
SUBSYSTEM_INT_SFTP : SUBSYSTEM_INT_SFTP_ERROR;
} else if (s->is_subsystem)
s->is_subsystem = SUBSYSTEM_EXT;
snprintf(session_type, sizeof(session_type),
"forced-command %s '%.900s'", forced, command);
} else if (s->is_subsystem) {
snprintf(session_type, sizeof(session_type),
"subsystem '%.900s'", s->subsys);
} else if (command == NULL) {
snprintf(session_type, sizeof(session_type), "shell");
} else {
/* NB. we don't log unforced commands to preserve privacy */
snprintf(session_type, sizeof(session_type), "command");
}
if (s->ttyfd != -1) {
tty = s->tty;
if (strncmp(tty, "/dev/", 5) == 0)
tty += 5;
}
verbose("Starting session: %s%s%s for %s from %.200s port %d id %d",
session_type,
tty == NULL ? "" : " on ",
tty == NULL ? "" : tty,
s->pw->pw_name,
ssh_remote_ipaddr(ssh),
ssh_remote_port(ssh),
s->self);
#ifdef GSSAPI
if (options.gss_authentication) {
temporarily_use_uid(s->pw);
ssh_gssapi_storecreds();
restore_uid();
}
#endif
if (s->ttyfd != -1)
ret = do_exec_pty(ssh, s, command);
else
ret = do_exec_no_pty(ssh, s, command);
original_command = NULL;
/*
* Clear loginmsg: it's the child's responsibility to display
* it to the user, otherwise multiple sessions may accumulate
* multiple copies of the login messages.
*/
sshbuf_reset(loginmsg);
return ret;
}
/* administrative, login(1)-like work */
void
do_login(struct ssh *ssh, Session *s, const char *command)
{
socklen_t fromlen;
struct sockaddr_storage from;
struct passwd * pw = s->pw;
pid_t pid = getpid();
/*
* Get IP address of client. If the connection is not a socket, let
* the address be 0.0.0.0.
*/
memset(&from, 0, sizeof(from));
fromlen = sizeof(from);
if (ssh_packet_connection_is_on_socket(ssh)) {
if (getpeername(ssh_packet_get_connection_in(ssh),
(struct sockaddr *)&from, &fromlen) == -1) {
debug("getpeername: %.100s", strerror(errno));
cleanup_exit(254);
}
}
/* Record that there was a login on that tty from the remote host. */
if (!use_privsep)
record_login(pid, s->tty, pw->pw_name, pw->pw_uid,
session_get_remote_name_or_ip(ssh, utmp_len,
options.use_dns),
(struct sockaddr *)&from, fromlen);
#ifdef USE_PAM
/*
* If password change is needed, do it now.
* This needs to occur before the ~/.hushlogin check.
*/
if (options.use_pam && !use_privsep && s->authctxt->force_pwchange) {
display_loginmsg();
do_pam_chauthtok();
s->authctxt->force_pwchange = 0;
/* XXX - signal [net] parent to enable forwardings */
}
#endif
if (check_quietlogin(s, command))
return;
display_loginmsg();
do_motd();
}
/*
* Display the message of the day.
*/
void
do_motd(void)
{
FILE *f;
char buf[256];
if (options.print_motd) {
#ifdef HAVE_LOGIN_CAP
f = fopen(login_getcapstr(lc, "welcome", __UNCONST("/etc/motd"),
__UNCONST("/etc/motd")), "r");
#else
f = fopen("/etc/motd", "r");
#endif
if (f) {
while (fgets(buf, sizeof(buf), f))
fputs(buf, stdout);
fclose(f);
}
}
}
/*
* Check for quiet login, either .hushlogin or command given.
*/
int
check_quietlogin(Session *s, const char *command)
{
char buf[256];
struct passwd *pw = s->pw;
struct stat st;
/* Return 1 if .hushlogin exists or a command given. */
if (command != NULL)
return 1;
snprintf(buf, sizeof(buf), "%.200s/.hushlogin", pw->pw_dir);
#ifdef HAVE_LOGIN_CAP
if (login_getcapbool(lc, "hushlogin", 0) || stat(buf, &st) >= 0)
return 1;
#else
if (stat(buf, &st) >= 0)
return 1;
#endif
return 0;
}
/*
* Reads environment variables from the given file and adds/overrides them
* into the environment. If the file does not exist, this does nothing.
* Otherwise, it must consist of empty lines, comments (line starts with '#')
* and assignments of the form name=value. No other forms are allowed.
* If whitelist is not NULL, then it is interpreted as a pattern list and
* only variable names that match it will be accepted.
*/
static void
read_environment_file(char ***env, u_int *envsize,
const char *filename, const char *whitelist)
{
FILE *f;
char *line = NULL, *cp, *value;
size_t linesize = 0;
u_int lineno = 0;
f = fopen(filename, "r");
if (!f)
return;
while (getline(&line, &linesize, f) != -1) {
if (++lineno > 1000)
fatal("Too many lines in environment file %s", filename);
for (cp = line; *cp == ' ' || *cp == '\t'; cp++)
;
if (!*cp || *cp == '#' || *cp == '\n')
continue;
cp[strcspn(cp, "\n")] = '\0';
value = strchr(cp, '=');
if (value == NULL) {
fprintf(stderr, "Bad line %u in %.100s\n", lineno,
filename);
continue;
}
/*
* Replace the equals sign by nul, and advance value to
* the value string.
*/
*value = '\0';
value++;
if (whitelist != NULL &&
match_pattern_list(cp, whitelist, 0) != 1)
continue;
child_set_env(env, envsize, cp, value);
}
free(line);
fclose(f);
}
#ifdef USE_PAM
void copy_environment(char **, char ***, u_int *);
void copy_environment(char **source, char ***env, u_int *envsize)
{
char *var_name, *var_val;
int i;
if (source == NULL)
return;
for (i = 0; source[i] != NULL; i++) {
var_name = xstrdup(source[i]);
if ((var_val = strstr(var_name, "=")) == NULL) {
free(var_name);
continue;
}
*var_val++ = '\0';
debug3("Copy environment: %s=%s", var_name, var_val);
child_set_env(env, envsize, var_name, var_val);
free(var_name);
}
}
#endif
static char **
do_setup_env(struct ssh *ssh, Session *s, const char *shell)
{
char buf[256];
size_t n;
u_int i, envsize;
char *ocp, *cp, *value, **env, *laddr;
struct passwd *pw = s->pw;
/* Initialize the environment. */
envsize = 100;
env = xcalloc(envsize, sizeof(char *));
env[0] = NULL;
#ifdef GSSAPI
/* Allow any GSSAPI methods that we've used to alter
* the childs environment as they see fit
*/
ssh_gssapi_do_child(&env, &envsize);
#endif
/* Set basic environment. */
for (i = 0; i < s->num_env; i++)
child_set_env(&env, &envsize, s->env[i].name, s->env[i].val);
child_set_env(&env, &envsize, "USER", pw->pw_name);
child_set_env(&env, &envsize, "LOGNAME", pw->pw_name);
child_set_env(&env, &envsize, "HOME", pw->pw_dir);
if (setusercontext(lc, pw, pw->pw_uid, LOGIN_SETPATH) < 0)
child_set_env(&env, &envsize, "PATH", _PATH_STDPATH);
else
child_set_env(&env, &envsize, "PATH", getenv("PATH"));
snprintf(buf, sizeof buf, "%.200s/%.50s", _PATH_MAILDIR, pw->pw_name);
child_set_env(&env, &envsize, "MAIL", buf);
/* Normal systems set SHELL by default. */
child_set_env(&env, &envsize, "SHELL", shell);
if (getenv("TZ"))
child_set_env(&env, &envsize, "TZ", getenv("TZ"));
if (s->term)
child_set_env(&env, &envsize, "TERM", s->term);
if (s->display)
child_set_env(&env, &envsize, "DISPLAY", s->display);
#ifdef KRB5
if (s->authctxt->krb5_ticket_file)
child_set_env(&env, &envsize, "KRB5CCNAME",
s->authctxt->krb5_ticket_file);
#endif
if (auth_sock_name != NULL)
child_set_env(&env, &envsize, SSH_AUTHSOCKET_ENV_NAME,
auth_sock_name);
/* Set custom environment options from pubkey authentication. */
if (options.permit_user_env) {
for (n = 0 ; n < auth_opts->nenv; n++) {
ocp = xstrdup(auth_opts->env[n]);
cp = strchr(ocp, '=');
if (*cp == '=') {
*cp = '\0';
/* Apply PermitUserEnvironment whitelist */
if (options.permit_user_env_whitelist == NULL ||
match_pattern_list(ocp,
options.permit_user_env_whitelist, 0) == 1)
child_set_env(&env, &envsize,
ocp, cp + 1);
}
free(ocp);
}
}
/* read $HOME/.ssh/environment. */
if (options.permit_user_env) {
snprintf(buf, sizeof buf, "%.200s/.ssh/environment",
pw->pw_dir);
read_environment_file(&env, &envsize, buf,
options.permit_user_env_whitelist);
}
/* Environment specified by admin */
for (i = 0; i < options.num_setenv; i++) {
cp = xstrdup(options.setenv[i]);
if ((value = strchr(cp, '=')) == NULL) {
/* shouldn't happen; vars are checked in servconf.c */
fatal("Invalid config SetEnv: %s", options.setenv[i]);
}
*value++ = '\0';
child_set_env(&env, &envsize, cp, value);
}
/* SSH_CLIENT deprecated */
snprintf(buf, sizeof buf, "%.50s %d %d",
ssh_remote_ipaddr(ssh), ssh_remote_port(ssh),
ssh_local_port(ssh));
child_set_env(&env, &envsize, "SSH_CLIENT", buf);
laddr = get_local_ipaddr(ssh_packet_get_connection_in(ssh));
snprintf(buf, sizeof buf, "%.50s %d %.50s %d",
ssh_remote_ipaddr(ssh), ssh_remote_port(ssh),
laddr, ssh_local_port(ssh));
free(laddr);
child_set_env(&env, &envsize, "SSH_CONNECTION", buf);
if (tun_fwd_ifnames != NULL)
child_set_env(&env, &envsize, "SSH_TUNNEL", tun_fwd_ifnames);
if (auth_info_file != NULL)
child_set_env(&env, &envsize, "SSH_USER_AUTH", auth_info_file);
if (s->ttyfd != -1)
child_set_env(&env, &envsize, "SSH_TTY", s->tty);
if (original_command)
child_set_env(&env, &envsize, "SSH_ORIGINAL_COMMAND",
original_command);
#ifdef KRB4
if (s->authctxt->krb4_ticket_file)
child_set_env(&env, &envsize, "KRBTKFILE",
s->authctxt->krb4_ticket_file);
#endif
#ifdef KRB5
if (s->authctxt->krb5_ticket_file)
child_set_env(&env, &envsize, "KRB5CCNAME",
s->authctxt->krb5_ticket_file);
#endif
#ifdef USE_PAM
/*
* Pull in any environment variables that may have
* been set by PAM.
*/
if (options.use_pam) {
char **p;
p = fetch_pam_child_environment();
copy_environment(p, &env, &envsize);
free_pam_environment(p);
p = fetch_pam_environment();
copy_environment(p, &env, &envsize);
free_pam_environment(p);
}
#endif /* USE_PAM */
if (debug_flag) {
/* dump the environment */
fprintf(stderr, "Environment:\n");
for (i = 0; env[i]; i++)
fprintf(stderr, " %.200s\n", env[i]);
}
return env;
}
/*
* Run $HOME/.ssh/rc, /etc/ssh/sshrc, or xauth (whichever is found
* first in this order).
*/
static void
do_rc_files(struct ssh *ssh, Session *s, const char *shell)
{
FILE *f = NULL;
char cmd[1024];
int do_xauth;
struct stat st;
do_xauth =
s->display != NULL && s->auth_proto != NULL && s->auth_data != NULL;
/* ignore _PATH_SSH_USER_RC for subsystems and admin forced commands */
if (!s->is_subsystem && options.adm_forced_command == NULL &&
auth_opts->permit_user_rc && options.permit_user_rc &&
stat(_PATH_SSH_USER_RC, &st) >= 0) {
snprintf(cmd, sizeof cmd, "%s -c '%s %s'",
shell, _PATH_BSHELL, _PATH_SSH_USER_RC);
if (debug_flag)
fprintf(stderr, "Running %s\n", cmd);
f = popen(cmd, "w");
if (f) {
if (do_xauth)
fprintf(f, "%s %s\n", s->auth_proto,
s->auth_data);
pclose(f);
} else
fprintf(stderr, "Could not run %s\n",
_PATH_SSH_USER_RC);
} else if (stat(_PATH_SSH_SYSTEM_RC, &st) >= 0) {
if (debug_flag)
fprintf(stderr, "Running %s %s\n", _PATH_BSHELL,
_PATH_SSH_SYSTEM_RC);
f = popen(_PATH_BSHELL " " _PATH_SSH_SYSTEM_RC, "w");
if (f) {
if (do_xauth)
fprintf(f, "%s %s\n", s->auth_proto,
s->auth_data);
pclose(f);
} else
fprintf(stderr, "Could not run %s\n",
_PATH_SSH_SYSTEM_RC);
} else if (do_xauth && options.xauth_location != NULL) {
/* Add authority data to .Xauthority if appropriate. */
if (debug_flag) {
fprintf(stderr,
"Running %.500s remove %.100s\n",
options.xauth_location, s->auth_display);
fprintf(stderr,
"%.500s add %.100s %.100s %.100s\n",
options.xauth_location, s->auth_display,
s->auth_proto, s->auth_data);
}
snprintf(cmd, sizeof cmd, "%s -q -",
options.xauth_location);
f = popen(cmd, "w");
if (f) {
fprintf(f, "remove %s\n",
s->auth_display);
fprintf(f, "add %s %s %s\n",
s->auth_display, s->auth_proto,
s->auth_data);
pclose(f);
} else {
fprintf(stderr, "Could not run %s\n",
cmd);
}
}
}
static void
do_nologin(struct passwd *pw)
{
FILE *f = NULL;
char buf[1024], *nl, *def_nl = __UNCONST(_PATH_NOLOGIN);
struct stat sb;
#ifdef HAVE_LOGIN_CAP
if (login_getcapbool(lc, "ignorenologin", 0) || pw->pw_uid == 0)
return;
nl = login_getcapstr(lc, "nologin", def_nl, def_nl);
#else
if (pw->pw_uid == 0)
return;
nl = def_nl;
#endif
if (stat(nl, &sb) == -1) {
if (nl != def_nl)
free(nl);
return;
}
/* /etc/nologin exists. Print its contents if we can and exit. */
logit("User %.100s not allowed because %s exists", pw->pw_name, nl);
if ((f = fopen(nl, "r")) != NULL) {
while (fgets(buf, sizeof(buf), f))
fputs(buf, stderr);
fclose(f);
}
exit(254);
}
/*
* Chroot into a directory after checking it for safety: all path components
* must be root-owned directories with strict permissions.
*/
static void
safely_chroot(const char *path, uid_t uid)
{
const char *cp;
char component[PATH_MAX];
struct stat st;
if (!path_absolute(path))
fatal("chroot path does not begin at root");
if (strlen(path) >= sizeof(component))
fatal("chroot path too long");
/*
* Descend the path, checking that each component is a
* root-owned directory with strict permissions.
*/
for (cp = path; cp != NULL;) {
if ((cp = strchr(cp, '/')) == NULL)
strlcpy(component, path, sizeof(component));
else {
cp++;
memcpy(component, path, cp - path);
component[cp - path] = '\0';
}
debug3("%s: checking '%s'", __func__, component);
if (stat(component, &st) != 0)
fatal("%s: stat(\"%s\"): %s", __func__,
component, strerror(errno));
if (st.st_uid != 0 || (st.st_mode & 022) != 0)
fatal("bad ownership or modes for chroot "
"directory %s\"%s\"",
cp == NULL ? "" : "component ", component);
if (!S_ISDIR(st.st_mode))
fatal("chroot path %s\"%s\" is not a directory",
cp == NULL ? "" : "component ", component);
}
if (chdir(path) == -1)
fatal("Unable to chdir to chroot path \"%s\": "
"%s", path, strerror(errno));
if (chroot(path) == -1)
fatal("chroot(\"%s\"): %s", path, strerror(errno));
if (chdir("/") == -1)
fatal("%s: chdir(/) after chroot: %s",
__func__, strerror(errno));
verbose("Changed root directory to \"%s\"", path);
}
/* Set login name, uid, gid, and groups. */
void
do_setusercontext(struct passwd *pw)
{
char uidstr[32], *chroot_path, *tmp;
if (getuid() == 0 || geteuid() == 0) {
#ifdef HAVE_LOGIN_CAP
# ifdef USE_PAM
if (options.use_pam) {
do_pam_setcred(use_privsep);
}
# endif /* USE_PAM */
/* Prepare groups */
if (setusercontext(lc, pw, pw->pw_uid,
(LOGIN_SETALL & ~(LOGIN_SETPATH|LOGIN_SETUSER))) < 0) {
perror("unable to set user context");
exit(1);
}
#else
if (setlogin(pw->pw_name) < 0)
error("setlogin failed: %s", strerror(errno));
if (setgid(pw->pw_gid) < 0) {
perror("setgid");
exit(1);
}
/* Initialize the group list. */
if (initgroups(pw->pw_name, pw->pw_gid) < 0) {
perror("initgroups");
exit(1);
}
endgrent();
# ifdef USE_PAM
/*
* PAM credentials may take the form of supplementary groups.
* These will have been wiped by the above initgroups() call.
* Reestablish them here.
*/
if (options.use_pam) {
do_pam_setcred(use_privsep);
}
# endif /* USE_PAM */
#endif
if (!in_chroot && options.chroot_directory != NULL &&
strcasecmp(options.chroot_directory, "none") != 0) {
tmp = tilde_expand_filename(options.chroot_directory,
pw->pw_uid);
snprintf(uidstr, sizeof(uidstr), "%llu",
(unsigned long long)pw->pw_uid);
chroot_path = percent_expand(tmp, "h", pw->pw_dir,
"u", pw->pw_name, "U", uidstr, (char *)NULL);
safely_chroot(chroot_path, pw->pw_uid);
free(tmp);
free(chroot_path);
/* Make sure we don't attempt to chroot again */
free(options.chroot_directory);
options.chroot_directory = NULL;
in_chroot = 1;
}
#ifdef HAVE_LOGIN_CAP
/* Set UID */
if (setusercontext(lc, pw, pw->pw_uid, LOGIN_SETUSER) < 0) {
perror("unable to set user context (setuser)");
exit(1);
}
#else
/* Permanently switch to the desired uid. */
permanently_set_uid(pw);
#endif
} else if (options.chroot_directory != NULL &&
strcasecmp(options.chroot_directory, "none") != 0) {
fatal("server lacks privileges to chroot to ChrootDirectory");
}
if (getuid() != pw->pw_uid || geteuid() != pw->pw_uid)
fatal("Failed to set uids to %u.", (u_int) pw->pw_uid);
}
__dead static void
do_pwchange(Session *s)
{
fflush(NULL);
fprintf(stderr, "WARNING: Your password has expired.\n");
if (s->ttyfd != -1) {
fprintf(stderr,
"You must change your password now and login again!\n");
execl(_PATH_PASSWD_PROG, "passwd", (char *)NULL);
perror("passwd");
} else {
fprintf(stderr,
"Password change required but no TTY available.\n");
}
exit(1);
}
static void
child_close_fds(struct ssh *ssh)
{
extern int auth_sock;
if (auth_sock != -1) {
close(auth_sock);
auth_sock = -1;
}
if (ssh_packet_get_connection_in(ssh) ==
ssh_packet_get_connection_out(ssh))
close(ssh_packet_get_connection_in(ssh));
else {
close(ssh_packet_get_connection_in(ssh));
close(ssh_packet_get_connection_out(ssh));
}
/*
* Close all descriptors related to channels. They will still remain
* open in the parent.
*/
/* XXX better use close-on-exec? -markus */
channel_close_all(ssh);
/*
* Close any extra file descriptors. Note that there may still be
* descriptors left by system functions. They will be closed later.
*/
endpwent();
/*
* Close any extra open file descriptors so that we don't have them
* hanging around in clients. Note that we want to do this after
* initgroups, because at least on Solaris 2.3 it leaves file
* descriptors open.
*/
(void)closefrom(STDERR_FILENO + 1);
}
/*
* Performs common processing for the child, such as setting up the
* environment, closing extra file descriptors, setting the user and group
* ids, and executing the command or shell.
*/
#define ARGV_MAX 10
void
do_child(struct ssh *ssh, Session *s, const char *command)
{
extern char **environ;
char **env, *argv[ARGV_MAX], remote_id[512];
const char *shell, *shell0;
struct passwd *pw = s->pw;
int r = 0;
sshpkt_fmt_connection_id(ssh, remote_id, sizeof(remote_id));
/* remove hostkey from the child's memory */
destroy_sensitive_data();
ssh_packet_clear_keys(ssh);
/* Force a password change */
if (s->authctxt->force_pwchange) {
do_setusercontext(pw);
child_close_fds(ssh);
do_pwchange(s);
}
/*
* Login(1) does this as well, and it needs uid 0 for the "-h"
* switch, so we let login(1) to this for us.
*/
#ifdef USE_PAM
if (options.use_pam && !is_pam_session_open()) {
debug3("PAM session not opened, exiting");
display_loginmsg();
exit(254);
}
#endif
do_nologin(pw);
do_setusercontext(pw);
/*
* Get the shell from the password data. An empty shell field is
* legal, and means /bin/sh.
*/
shell = (pw->pw_shell[0] == '\0') ? _PATH_BSHELL : pw->pw_shell;
/*
* Make sure $SHELL points to the shell from the password file,
* even if shell is overridden from login.conf
*/
env = do_setup_env(ssh, s, shell);
#ifdef HAVE_LOGIN_CAP
shell = login_getcapstr(lc, "shell", __UNCONST(shell),
__UNCONST(shell));
#endif
/*
* Close the connection descriptors; note that this is the child, and
* the server will still have the socket open, and it is important
* that we do not shutdown it. Note that the descriptors cannot be
* closed before building the environment, as we call
* ssh_remote_ipaddr there.
*/
child_close_fds(ssh);
/*
* Must take new environment into use so that .ssh/rc,
* /etc/ssh/sshrc and xauth are run in the proper environment.
*/
environ = env;
#ifdef KRB5
/*
* At this point, we check to see if AFS is active and if we have
* a valid Kerberos 5 TGT. If so, it seems like a good idea to see
* if we can (and need to) extend the ticket into an AFS token. If
* we don't do this, we run into potential problems if the user's
* home directory is in AFS and it's not world-readable.
*/
if (options.kerberos_get_afs_token && k_hasafs() &&
(s->authctxt->krb5_ctx != NULL)) {
char cell[64];
debug("Getting AFS token");
k_setpag();
if (k_afs_cell_of_file(pw->pw_dir, cell, sizeof(cell)) == 0)
krb5_afslog(s->authctxt->krb5_ctx,
s->authctxt->krb5_fwd_ccache, cell, NULL);
krb5_afslog_home(s->authctxt->krb5_ctx,
s->authctxt->krb5_fwd_ccache, NULL, NULL, pw->pw_dir);
}
#endif
/* Change current directory to the user's home directory. */
if (chdir(pw->pw_dir) == -1) {
/* Suppress missing homedir warning for chroot case */
r = login_getcapbool(lc, "requirehome", 0);
if (r || !in_chroot) {
fprintf(stderr, "Could not chdir to home "
"directory %s: %s\n", pw->pw_dir,
strerror(errno));
}
if (r)
exit(1);
}
(void)closefrom(STDERR_FILENO + 1);
do_rc_files(ssh, s, shell);
/* restore SIGPIPE for child */
ssh_signal(SIGPIPE, SIG_DFL);
if (s->is_subsystem == SUBSYSTEM_INT_SFTP_ERROR) {
error("Connection from %s: refusing non-sftp session",
remote_id);
printf("This service allows sftp connections only.\n");
fflush(NULL);
exit(1);
} else if (s->is_subsystem == SUBSYSTEM_INT_SFTP) {
extern int optind, optreset;
int i;
char *p, *args;
setproctitle("%s@%s", s->pw->pw_name, INTERNAL_SFTP_NAME);
args = xstrdup(command ? command : "sftp-server");
for (i = 0, (p = strtok(args, " ")); p; (p = strtok(NULL, " ")))
if (i < ARGV_MAX - 1)
argv[i++] = p;
argv[i] = NULL;
optind = optreset = 1;
__progname = argv[0];
exit(sftp_server_main(i, argv, s->pw));
}
fflush(NULL);
/* Get the last component of the shell name. */
if ((shell0 = strrchr(shell, '/')) != NULL)
shell0++;
else
shell0 = shell;
/*
* If we have no command, execute the shell. In this case, the shell
* name to be passed in argv[0] is preceded by '-' to indicate that
* this is a login shell.
*/
if (!command) {
char argv0[256];
/* Start the shell. Set initial character to '-'. */
argv0[0] = '-';
if (strlcpy(argv0 + 1, shell0, sizeof(argv0) - 1)
>= sizeof(argv0) - 1) {
errno = EINVAL;
perror(shell);
exit(1);
}
/* Execute the shell. */
argv[0] = argv0;
argv[1] = NULL;
execve(shell, argv, env);
/* Executing the shell failed. */
perror(shell);
exit(1);
}
/*
* Execute the command using the user's shell. This uses the -c
* option to execute the command.
*/
argv[0] = __UNCONST(shell0);
argv[1] = __UNCONST("-c");
argv[2] = __UNCONST(command);
argv[3] = NULL;
execve(shell, argv, env);
perror(shell);
exit(1);
}
void
session_unused(int id)
{
debug3("%s: session id %d unused", __func__, id);
if (id >= options.max_sessions ||
id >= sessions_nalloc) {
fatal("%s: insane session id %d (max %d nalloc %d)",
__func__, id, options.max_sessions, sessions_nalloc);
}
memset(&sessions[id], 0, sizeof(*sessions));
sessions[id].self = id;
sessions[id].used = 0;
sessions[id].chanid = -1;
sessions[id].ptyfd = -1;
sessions[id].ttyfd = -1;
sessions[id].ptymaster = -1;
sessions[id].x11_chanids = NULL;
sessions[id].next_unused = sessions_first_unused;
sessions_first_unused = id;
}
Session *
session_new(void)
{
Session *s, *tmp;
if (sessions_first_unused == -1) {
if (sessions_nalloc >= options.max_sessions)
return NULL;
debug2("%s: allocate (allocated %d max %d)",
__func__, sessions_nalloc, options.max_sessions);
tmp = xrecallocarray(sessions, sessions_nalloc,
sessions_nalloc + 1, sizeof(*sessions));
if (tmp == NULL) {
error("%s: cannot allocate %d sessions",
__func__, sessions_nalloc + 1);
return NULL;
}
sessions = tmp;
session_unused(sessions_nalloc++);
}
if (sessions_first_unused >= sessions_nalloc ||
sessions_first_unused < 0) {
fatal("%s: insane first_unused %d max %d nalloc %d",
__func__, sessions_first_unused, options.max_sessions,
sessions_nalloc);
}
s = &sessions[sessions_first_unused];
if (s->used) {
fatal("%s: session %d already used",
__func__, sessions_first_unused);
}
sessions_first_unused = s->next_unused;
s->used = 1;
s->next_unused = -1;
debug("session_new: session %d", s->self);
return s;
}
static void
session_dump(void)
{
int i;
for (i = 0; i < sessions_nalloc; i++) {
Session *s = &sessions[i];
debug("dump: used %d next_unused %d session %d %p "
"channel %d pid %ld",
s->used,
s->next_unused,
s->self,
s,
s->chanid,
(long)s->pid);
}
}
int
session_open(Authctxt *authctxt, int chanid)
{
Session *s = session_new();
debug("session_open: channel %d", chanid);
if (s == NULL) {
error("no more sessions");
return 0;
}
s->authctxt = authctxt;
s->pw = authctxt->pw;
if (s->pw == NULL || !authctxt->valid)
fatal("no user for session %d", s->self);
debug("session_open: session %d: link with channel %d", s->self, chanid);
s->chanid = chanid;
return 1;
}
Session *
session_by_tty(char *tty)
{
int i;
for (i = 0; i < sessions_nalloc; i++) {
Session *s = &sessions[i];
if (s->used && s->ttyfd != -1 && strcmp(s->tty, tty) == 0) {
debug("session_by_tty: session %d tty %s", i, tty);
return s;
}
}
debug("session_by_tty: unknown tty %.100s", tty);
session_dump();
return NULL;
}
static Session *
session_by_channel(int id)
{
int i;
for (i = 0; i < sessions_nalloc; i++) {
Session *s = &sessions[i];
if (s->used && s->chanid == id) {
debug("session_by_channel: session %d channel %d",
i, id);
return s;
}
}
debug("session_by_channel: unknown channel %d", id);
session_dump();
return NULL;
}
static Session *
session_by_x11_channel(int id)
{
int i, j;
for (i = 0; i < sessions_nalloc; i++) {
Session *s = &sessions[i];
if (s->x11_chanids == NULL || !s->used)
continue;
for (j = 0; s->x11_chanids[j] != -1; j++) {
if (s->x11_chanids[j] == id) {
debug("session_by_x11_channel: session %d "
"channel %d", s->self, id);
return s;
}
}
}
debug("session_by_x11_channel: unknown channel %d", id);
session_dump();
return NULL;
}
static Session *
session_by_pid(pid_t pid)
{
int i;
debug("session_by_pid: pid %ld", (long)pid);
for (i = 0; i < sessions_nalloc; i++) {
Session *s = &sessions[i];
if (s->used && s->pid == pid)
return s;
}
error("session_by_pid: unknown pid %ld", (long)pid);
session_dump();
return NULL;
}
static int
session_window_change_req(struct ssh *ssh, Session *s)
{
int r;
if ((r = sshpkt_get_u32(ssh, &s->col)) != 0 ||
(r = sshpkt_get_u32(ssh, &s->row)) != 0 ||
(r = sshpkt_get_u32(ssh, &s->xpixel)) != 0 ||
(r = sshpkt_get_u32(ssh, &s->ypixel)) != 0 ||
(r = sshpkt_get_end(ssh)) != 0)
sshpkt_fatal(ssh, r, "%s: parse packet", __func__);
pty_change_window_size(s->ptyfd, s->row, s->col, s->xpixel, s->ypixel);
return 1;
}
static int
session_pty_req(struct ssh *ssh, Session *s)
{
int r;
if (!auth_opts->permit_pty_flag || !options.permit_tty) {
debug("Allocating a pty not permitted for this connection.");
return 0;
}
if (s->ttyfd != -1) {
ssh_packet_disconnect(ssh, "Protocol error: you already have a pty.");
return 0;
}
if ((r = sshpkt_get_cstring(ssh, &s->term, NULL)) != 0 ||
(r = sshpkt_get_u32(ssh, &s->col)) != 0 ||
(r = sshpkt_get_u32(ssh, &s->row)) != 0 ||
(r = sshpkt_get_u32(ssh, &s->xpixel)) != 0 ||
(r = sshpkt_get_u32(ssh, &s->ypixel)) != 0)
sshpkt_fatal(ssh, r, "%s: parse packet", __func__);
if (strcmp(s->term, "") == 0) {
free(s->term);
s->term = NULL;
}
/* Allocate a pty and open it. */
debug("Allocating pty.");
if (!PRIVSEP(pty_allocate(&s->ptyfd, &s->ttyfd, s->tty,
sizeof(s->tty)))) {
free(s->term);
s->term = NULL;
s->ptyfd = -1;
s->ttyfd = -1;
error("session_pty_req: session %d alloc failed", s->self);
return 0;
}
debug("session_pty_req: session %d alloc %s", s->self, s->tty);
ssh_tty_parse_modes(ssh, s->ttyfd);
if ((r = sshpkt_get_end(ssh)) != 0)
sshpkt_fatal(ssh, r, "%s: parse packet", __func__);
if (!use_privsep)
pty_setowner(s->pw, s->tty);
/* Set window size from the packet. */
pty_change_window_size(s->ptyfd, s->row, s->col, s->xpixel, s->ypixel);
session_proctitle(s);
return 1;
}
static int
session_subsystem_req(struct ssh *ssh, Session *s)
{
struct stat st;
int r, success = 0;
char *prog, *cmd;
u_int i;
if ((r = sshpkt_get_cstring(ssh, &s->subsys, NULL)) != 0 ||
(r = sshpkt_get_end(ssh)) != 0)
sshpkt_fatal(ssh, r, "%s: parse packet", __func__);
debug2("subsystem request for %.100s by user %s", s->subsys,
s->pw->pw_name);
for (i = 0; i < options.num_subsystems; i++) {
if (strcmp(s->subsys, options.subsystem_name[i]) == 0) {
prog = options.subsystem_command[i];
cmd = options.subsystem_args[i];
if (strcmp(INTERNAL_SFTP_NAME, prog) == 0) {
s->is_subsystem = SUBSYSTEM_INT_SFTP;
debug("subsystem: %s", prog);
} else {
if (stat(prog, &st) == -1)
debug("subsystem: cannot stat %s: %s",
prog, strerror(errno));
s->is_subsystem = SUBSYSTEM_EXT;
debug("subsystem: exec() %s", cmd);
}
success = do_exec(ssh, s, cmd) == 0;
break;
}
}
if (!success)
logit("subsystem request for %.100s by user %s failed, "
"subsystem not found", s->subsys, s->pw->pw_name);
return success;
}
static int
session_x11_req(struct ssh *ssh, Session *s)
{
int r, success;
u_char single_connection = 0;
if (s->auth_proto != NULL || s->auth_data != NULL) {
error("session_x11_req: session %d: "
"x11 forwarding already active", s->self);
return 0;
}
if ((r = sshpkt_get_u8(ssh, &single_connection)) != 0 ||
(r = sshpkt_get_cstring(ssh, &s->auth_proto, NULL)) != 0 ||
(r = sshpkt_get_cstring(ssh, &s->auth_data, NULL)) != 0 ||
(r = sshpkt_get_u32(ssh, &s->screen)) != 0 ||
(r = sshpkt_get_end(ssh)) != 0)
sshpkt_fatal(ssh, r, "%s: parse packet", __func__);
s->single_connection = single_connection;
if (xauth_valid_string(s->auth_proto) &&
xauth_valid_string(s->auth_data))
success = session_setup_x11fwd(ssh, s);
else {
success = 0;
error("Invalid X11 forwarding data");
}
if (!success) {
free(s->auth_proto);
free(s->auth_data);
s->auth_proto = NULL;
s->auth_data = NULL;
}
return success;
}
static int
session_shell_req(struct ssh *ssh, Session *s)
{
int r;
if ((r = sshpkt_get_end(ssh)) != 0)
sshpkt_fatal(ssh, r, "%s: parse packet", __func__);
return do_exec(ssh, s, NULL) == 0;
}
static int
session_exec_req(struct ssh *ssh, Session *s)
{
u_int success;
int r;
char *command = NULL;
if ((r = sshpkt_get_cstring(ssh, &command, NULL)) != 0 ||
(r = sshpkt_get_end(ssh)) != 0)
sshpkt_fatal(ssh, r, "%s: parse packet", __func__);
success = do_exec(ssh, s, command) == 0;
free(command);
return success;
}
static int
session_break_req(struct ssh *ssh, Session *s)
{
int r;
if ((r = sshpkt_get_u32(ssh, NULL)) != 0 || /* ignore */
(r = sshpkt_get_end(ssh)) != 0)
sshpkt_fatal(ssh, r, "%s: parse packet", __func__);
if (s->ptymaster == -1 || tcsendbreak(s->ptymaster, 0) == -1)
return 0;
return 1;
}
static int
session_env_req(struct ssh *ssh, Session *s)
{
char *name, *val;
u_int i;
int r;
if ((r = sshpkt_get_cstring(ssh, &name, NULL)) != 0 ||
(r = sshpkt_get_cstring(ssh, &val, NULL)) != 0 ||
(r = sshpkt_get_end(ssh)) != 0)
sshpkt_fatal(ssh, r, "%s: parse packet", __func__);
/* Don't set too many environment variables */
if (s->num_env > 128) {
debug2("Ignoring env request %s: too many env vars", name);
goto fail;
}
for (i = 0; i < options.num_accept_env; i++) {
if (match_pattern(name, options.accept_env[i])) {
debug2("Setting env %d: %s=%s", s->num_env, name, val);
s->env = xrecallocarray(s->env, s->num_env,
s->num_env + 1, sizeof(*s->env));
s->env[s->num_env].name = name;
s->env[s->num_env].val = val;
s->num_env++;
return (1);
}
}
debug2("Ignoring env request %s: disallowed name", name);
fail:
free(name);
free(val);
return (0);
}
/*
* Conversion of signals from ssh channel request names.
* Subset of signals from RFC 4254 section 6.10C, with SIGINFO as
* local extension.
*/
static int
name2sig(char *name)
{
#define SSH_SIG(x) if (strcmp(name, #x) == 0) return SIG ## x
SSH_SIG(HUP);
SSH_SIG(INT);
SSH_SIG(KILL);
SSH_SIG(QUIT);
SSH_SIG(TERM);
SSH_SIG(USR1);
SSH_SIG(USR2);
#undef SSH_SIG
if (strcmp(name, "INFO@openssh.com") == 0)
return SIGINFO;
return -1;
}
static int
session_signal_req(struct ssh *ssh, Session *s)
{
char *signame = NULL;
int r, sig, success = 0;
if ((r = sshpkt_get_cstring(ssh, &signame, NULL)) != 0 ||
(r = sshpkt_get_end(ssh)) != 0) {
error("%s: parse packet: %s", __func__, ssh_err(r));
goto out;
}
if ((sig = name2sig(signame)) == -1) {
error("%s: unsupported signal \"%s\"", __func__, signame);
goto out;
}
if (s->pid <= 0) {
error("%s: no pid for session %d", __func__, s->self);
goto out;
}
if (s->forced || s->is_subsystem) {
error("%s: refusing to send signal %s to %s session", __func__,
signame, s->forced ? "forced-command" : "subsystem");
goto out;
}
if (!use_privsep || mm_is_monitor()) {
error("%s: session signalling requires privilege separation",
__func__);
goto out;
}
debug("%s: signal %s, killpg(%ld, %d)", __func__, signame,
(long)s->pid, sig);
temporarily_use_uid(s->pw);
r = killpg(s->pid, sig);
restore_uid();
if (r != 0) {
error("%s: killpg(%ld, %d): %s", __func__, (long)s->pid,
sig, strerror(errno));
goto out;
}
/* success */
success = 1;
out:
free(signame);
return success;
}
static int
session_auth_agent_req(struct ssh *ssh, Session *s)
{
static int called = 0;
int r;
if ((r = sshpkt_get_end(ssh)) != 0)
sshpkt_fatal(ssh, r, "%s: parse packet", __func__);
if (!auth_opts->permit_agent_forwarding_flag ||
!options.allow_agent_forwarding) {
debug("%s: agent forwarding disabled", __func__);
return 0;
}
if (called) {
return 0;
} else {
called = 1;
return auth_input_request_forwarding(ssh, s->pw);
}
}
int
session_input_channel_req(struct ssh *ssh, Channel *c, const char *rtype)
{
int success = 0;
Session *s;
if ((s = session_by_channel(c->self)) == NULL) {
logit("%s: no session %d req %.100s", __func__, c->self, rtype);
return 0;
}
debug("%s: session %d req %s", __func__, s->self, rtype);
/*
* a session is in LARVAL state until a shell, a command
* or a subsystem is executed
*/
if (c->type == SSH_CHANNEL_LARVAL) {
if (strcmp(rtype, "shell") == 0) {
success = session_shell_req(ssh, s);
} else if (strcmp(rtype, "exec") == 0) {
success = session_exec_req(ssh, s);
} else if (strcmp(rtype, "pty-req") == 0) {
success = session_pty_req(ssh, s);
} else if (strcmp(rtype, "x11-req") == 0) {
success = session_x11_req(ssh, s);
} else if (strcmp(rtype, "auth-agent-req@openssh.com") == 0) {
success = session_auth_agent_req(ssh, s);
} else if (strcmp(rtype, "subsystem") == 0) {
success = session_subsystem_req(ssh, s);
} else if (strcmp(rtype, "env") == 0) {
success = session_env_req(ssh, s);
}
}
if (strcmp(rtype, "window-change") == 0) {
success = session_window_change_req(ssh, s);
} else if (strcmp(rtype, "break") == 0) {
success = session_break_req(ssh, s);
} else if (strcmp(rtype, "signal") == 0) {
success = session_signal_req(ssh, s);
}
return success;
}
void
session_set_fds(struct ssh *ssh, Session *s,
int fdin, int fdout, int fderr, int ignore_fderr, int is_tty)
{
/*
* now that have a child and a pipe to the child,
* we can activate our channel and register the fd's
*/
if (s->chanid == -1)
fatal("no channel for session %d", s->self);
if(options.hpn_disabled)
channel_set_fds(ssh, s->chanid,
fdout, fdin, fderr,
ignore_fderr ? CHAN_EXTENDED_IGNORE : CHAN_EXTENDED_READ,
1, is_tty, CHAN_SES_WINDOW_DEFAULT);
else
channel_set_fds(ssh, s->chanid,
fdout, fdin, fderr,
ignore_fderr ? CHAN_EXTENDED_IGNORE : CHAN_EXTENDED_READ,
1, is_tty, options.hpn_buffer_size);
}
/*
* Function to perform pty cleanup. Also called if we get aborted abnormally
* (e.g., due to a dropped connection).
*/
void
session_pty_cleanup2(Session *s)
{
if (s == NULL) {
error("%s: no session", __func__);
return;
}
if (s->ttyfd == -1)
return;
debug("%s: session %d release %s", __func__, s->self, s->tty);
/* Record that the user has logged out. */
if (s->pid != 0)
record_logout(s->pid, s->tty);
/* Release the pseudo-tty. */
if (getuid() == 0)
pty_release(s->tty);
/*
* Close the server side of the socket pairs. We must do this after
* the pty cleanup, so that another process doesn't get this pty
* while we're still cleaning up.
*/
if (s->ptymaster != -1 && close(s->ptymaster) == -1)
error("close(s->ptymaster/%d): %s",
s->ptymaster, strerror(errno));
/* unlink pty from session */
s->ttyfd = -1;
}
void
session_pty_cleanup(Session *s)
{
PRIVSEP(session_pty_cleanup2(s));
}
static const char *
sig2name(int sig)
{
#define SSH_SIG(x) if (sig == SIG ## x) return #x
SSH_SIG(ABRT);
SSH_SIG(ALRM);
SSH_SIG(FPE);
SSH_SIG(HUP);
SSH_SIG(ILL);
SSH_SIG(INT);
SSH_SIG(KILL);
SSH_SIG(PIPE);
SSH_SIG(QUIT);
SSH_SIG(SEGV);
SSH_SIG(TERM);
SSH_SIG(USR1);
SSH_SIG(USR2);
#undef SSH_SIG
return "SIG@openssh.com";
}
static void
session_close_x11(struct ssh *ssh, int id)
{
Channel *c;
if ((c = channel_by_id(ssh, id)) == NULL) {
debug("%s: x11 channel %d missing", __func__, id);
} else {
/* Detach X11 listener */
debug("%s: detach x11 channel %d", __func__, id);
channel_cancel_cleanup(ssh, id);
if (c->ostate != CHAN_OUTPUT_CLOSED)
chan_mark_dead(ssh, c);
}
}
static void
session_close_single_x11(struct ssh *ssh, int id, void *arg)
{
Session *s;
u_int i;
debug3("%s: channel %d", __func__, id);
channel_cancel_cleanup(ssh, id);
if ((s = session_by_x11_channel(id)) == NULL)
fatal("%s: no x11 channel %d", __func__, id);
for (i = 0; s->x11_chanids[i] != -1; i++) {
debug("%s: session %d: closing channel %d",
__func__, s->self, s->x11_chanids[i]);
/*
* The channel "id" is already closing, but make sure we
* close all of its siblings.
*/
if (s->x11_chanids[i] != id)
session_close_x11(ssh, s->x11_chanids[i]);
}
free(s->x11_chanids);
s->x11_chanids = NULL;
free(s->display);
s->display = NULL;
free(s->auth_proto);
s->auth_proto = NULL;
free(s->auth_data);
s->auth_data = NULL;
free(s->auth_display);
s->auth_display = NULL;
}
static void
session_exit_message(struct ssh *ssh, Session *s, int status)
{
Channel *c;
int r;
if ((c = channel_lookup(ssh, s->chanid)) == NULL)
fatal("%s: session %d: no channel %d",
__func__, s->self, s->chanid);
debug("%s: session %d channel %d pid %ld",
__func__, s->self, s->chanid, (long)s->pid);
if (WIFEXITED(status)) {
channel_request_start(ssh, s->chanid, "exit-status", 0);
if ((r = sshpkt_put_u32(ssh, WEXITSTATUS(status))) != 0 ||
(r = sshpkt_send(ssh)) != 0)
sshpkt_fatal(ssh, r, "%s: exit reply", __func__);
} else if (WIFSIGNALED(status)) {
channel_request_start(ssh, s->chanid, "exit-signal", 0);
if ((r = sshpkt_put_cstring(ssh, sig2name(WTERMSIG(status)))) != 0 ||
(r = sshpkt_put_u8(ssh, WCOREDUMP(status)? 1 : 0)) != 0 ||
(r = sshpkt_put_cstring(ssh, "")) != 0 ||
(r = sshpkt_put_cstring(ssh, "")) != 0 ||
(r = sshpkt_send(ssh)) != 0)
sshpkt_fatal(ssh, r, "%s: exit reply", __func__);
} else {
/* Some weird exit cause. Just exit. */
ssh_packet_disconnect(ssh, "wait returned status %04x.", status);
}
/* disconnect channel */
debug("%s: release channel %d", __func__, s->chanid);
/*
* Adjust cleanup callback attachment to send close messages when
* the channel gets EOF. The session will be then be closed
* by session_close_by_channel when the childs close their fds.
*/
channel_register_cleanup(ssh, c->self, session_close_by_channel, 1);
/*
* emulate a write failure with 'chan_write_failed', nobody will be
* interested in data we write.
* Note that we must not call 'chan_read_failed', since there could
* be some more data waiting in the pipe.
*/
if (c->ostate != CHAN_OUTPUT_CLOSED)
chan_write_failed(ssh, c);
}
void
session_close(struct ssh *ssh, Session *s)
{
u_int i;
verbose("Close session: user %s from %.200s port %d id %d",
s->pw->pw_name,
ssh_remote_ipaddr(ssh),
ssh_remote_port(ssh),
s->self);
if (s->ttyfd != -1)
session_pty_cleanup(s);
free(s->term);
free(s->display);
free(s->x11_chanids);
free(s->auth_display);
free(s->auth_data);
free(s->auth_proto);
free(s->subsys);
if (s->env != NULL) {
for (i = 0; i < s->num_env; i++) {
free(s->env[i].name);
free(s->env[i].val);
}
free(s->env);
}
session_proctitle(s);
session_unused(s->self);
}
void
session_close_by_pid(struct ssh *ssh, pid_t pid, int status)
{
Session *s = session_by_pid(pid);
if (s == NULL) {
debug("%s: no session for pid %ld", __func__, (long)pid);
return;
}
if (s->chanid != -1)
session_exit_message(ssh, s, status);
if (s->ttyfd != -1)
session_pty_cleanup(s);
s->pid = 0;
}
/*
* this is called when a channel dies before
* the session 'child' itself dies
*/
void
session_close_by_channel(struct ssh *ssh, int id, void *arg)
{
Session *s = session_by_channel(id);
u_int i;
if (s == NULL) {
debug("%s: no session for id %d", __func__, id);
return;
}
debug("%s: channel %d child %ld", __func__, id, (long)s->pid);
if (s->pid != 0) {
debug("%s: channel %d: has child, ttyfd %d",
__func__, id, s->ttyfd);
/*
* delay detach of session, but release pty, since
* the fd's to the child are already closed
*/
if (s->ttyfd != -1)
session_pty_cleanup(s);
return;
}
/* detach by removing callback */
channel_cancel_cleanup(ssh, s->chanid);
/* Close any X11 listeners associated with this session */
if (s->x11_chanids != NULL) {
for (i = 0; s->x11_chanids[i] != -1; i++) {
session_close_x11(ssh, s->x11_chanids[i]);
s->x11_chanids[i] = -1;
}
}
s->chanid = -1;
session_close(ssh, s);
}
void
session_destroy_all(struct ssh *ssh, void (*closefunc)(Session *))
{
int i;
for (i = 0; i < sessions_nalloc; i++) {
Session *s = &sessions[i];
if (s->used) {
if (closefunc != NULL)
closefunc(s);
else
session_close(ssh, s);
}
}
}
static char *
session_tty_list(void)
{
static char buf[1024];
int i;
buf[0] = '\0';
for (i = 0; i < sessions_nalloc; i++) {
Session *s = &sessions[i];
if (s->used && s->ttyfd != -1) {
char *p;
if (buf[0] != '\0')
strlcat(buf, ",", sizeof buf);
if ((p = strstr(s->tty, "/pts/")) != NULL)
p++;
else {
if ((p = strrchr(s->tty, '/')) != NULL)
p++;
else
p = s->tty;
}
strlcat(buf, p, sizeof buf);
}
}
if (buf[0] == '\0')
strlcpy(buf, "notty", sizeof buf);
return buf;
}
void
session_proctitle(Session *s)
{
if (s->pw == NULL)
error("no user for session %d", s->self);
else
setproctitle("%s@%s", s->pw->pw_name, session_tty_list());
}
int
session_setup_x11fwd(struct ssh *ssh, Session *s)
{
struct stat st;
char display[512], auth_display[512];
char hostname[NI_MAXHOST];
u_int i;
if (!auth_opts->permit_x11_forwarding_flag) {
ssh_packet_send_debug(ssh, "X11 forwarding disabled by key options.");
return 0;
}
if (!options.x11_forwarding) {
debug("X11 forwarding disabled in server configuration file.");
return 0;
}
if (options.xauth_location == NULL ||
(stat(options.xauth_location, &st) == -1)) {
ssh_packet_send_debug(ssh, "No xauth program; cannot forward X11.");
return 0;
}
if (s->display != NULL) {
debug("X11 display already set.");
return 0;
}
if (x11_create_display_inet(ssh, options.x11_display_offset,
options.x11_use_localhost, s->single_connection,
&s->display_number, &s->x11_chanids) == -1) {
debug("x11_create_display_inet failed.");
return 0;
}
for (i = 0; s->x11_chanids[i] != -1; i++) {
channel_register_cleanup(ssh, s->x11_chanids[i],
session_close_single_x11, 0);
}
/* Set up a suitable value for the DISPLAY variable. */
if (gethostname(hostname, sizeof(hostname)) == -1)
fatal("gethostname: %.100s", strerror(errno));
/*
* auth_display must be used as the displayname when the
* authorization entry is added with xauth(1). This will be
* different than the DISPLAY string for localhost displays.
*/
if (options.x11_use_localhost) {
snprintf(display, sizeof display, "localhost:%u.%u",
s->display_number, s->screen);
snprintf(auth_display, sizeof auth_display, "unix:%u.%u",
s->display_number, s->screen);
s->display = xstrdup(display);
s->auth_display = xstrdup(auth_display);
} else {
snprintf(display, sizeof display, "%.400s:%u.%u", hostname,
s->display_number, s->screen);
s->display = xstrdup(display);
s->auth_display = xstrdup(display);
}
return 1;
}
static void
do_authenticated2(struct ssh *ssh, Authctxt *authctxt)
{
server_loop2(ssh, authctxt);
}
void
do_cleanup(struct ssh *ssh, Authctxt *authctxt)
{
static int called = 0;
debug("do_cleanup");
/* no cleanup if we're in the child for login shell */
if (is_child)
return;
/* avoid double cleanup */
if (called)
return;
called = 1;
if (authctxt == NULL || !authctxt->authenticated)
return;
#ifdef KRB4
if (options.kerberos_ticket_cleanup)
krb4_cleanup_proc(authctxt);
#endif
#ifdef KRB5
if (options.kerberos_ticket_cleanup &&
authctxt->krb5_ctx)
krb5_cleanup_proc(authctxt);
#endif
#ifdef GSSAPI
if (options.gss_cleanup_creds)
ssh_gssapi_cleanup_creds();
#endif
#ifdef USE_PAM
if (options.use_pam) {
sshpam_cleanup();
sshpam_thread_cleanup();
}
#endif
/* remove agent socket */
auth_sock_cleanup_proc(authctxt->pw);
/* remove userauth info */
if (auth_info_file != NULL) {
temporarily_use_uid(authctxt->pw);
unlink(auth_info_file);
restore_uid();
free(auth_info_file);
auth_info_file = NULL;
}
/*
* Cleanup ptys/utmp only if privsep is disabled,
* or if running in monitor.
*/
if (!use_privsep || mm_is_monitor())
session_destroy_all(ssh, session_pty_cleanup2);
}
/* Return a name for the remote host that fits inside utmp_size */
const char *
session_get_remote_name_or_ip(struct ssh *ssh, u_int utmp_size, int use_dns)
{
const char *remote = "";
if (utmp_size > 0)
remote = auth_get_canonical_hostname(ssh, use_dns);
if (utmp_size == 0 || strlen(remote) > utmp_size)
remote = ssh_remote_ipaddr(ssh);
return remote;
}
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