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openssh/session.c
Damien Miller 3a961dc0d3 - (djm) OpenBSD CVS Sync 
- markus@cvs.openbsd.org 2003/06/02 09:17:34
     [auth2-hostbased.c auth.c auth-options.c auth-rhosts.c auth-rh-rsa.c]
     [canohost.c monitor.c servconf.c servconf.h session.c sshd_config]
     [sshd_config.5]
     deprecate VerifyReverseMapping since it's dangerous if combined
     with IP based access control as noted by Mike Harding; replace with
     a UseDNS option, UseDNS is on by default and includes the
     VerifyReverseMapping check; with itojun@, provos@, jakob@ and deraadt@
     ok deraadt@, djm@
 - (djm) Fix portable-specific uses of verify_reverse_mapping too
2003-06-03 10:25:48 +10:00

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/*
* 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("$OpenBSD: session.c,v 1.158 2003/06/02 09:17:34 markus Exp $");
#include "ssh.h"
#include "ssh1.h"
#include "ssh2.h"
#include "xmalloc.h"
#include "sshpty.h"
#include "packet.h"
#include "buffer.h"
#include "mpaux.h"
#include "uidswap.h"
#include "compat.h"
#include "channels.h"
#include "bufaux.h"
#include "auth.h"
#include "auth-options.h"
#include "pathnames.h"
#include "log.h"
#include "servconf.h"
#include "sshlogin.h"
#include "serverloop.h"
#include "canohost.h"
#include "session.h"
#include "monitor_wrap.h"
#ifdef HAVE_CYGWIN
#include <windows.h>
#include <sys/cygwin.h>
#define is_winnt (GetVersion() < 0x80000000)
#endif
/* func */
Session *session_new(void);
void session_set_fds(Session *, int, int, int);
void session_pty_cleanup(void *);
void session_proctitle(Session *);
int session_setup_x11fwd(Session *);
void do_exec_pty(Session *, const char *);
void do_exec_no_pty(Session *, const char *);
void do_exec(Session *, const char *);
void do_login(Session *, const char *);
#ifdef LOGIN_NEEDS_UTMPX
static void do_pre_login(Session *s);
#endif
void do_child(Session *, const char *);
void do_motd(void);
int check_quietlogin(Session *, const char *);
static void do_authenticated1(Authctxt *);
static void do_authenticated2(Authctxt *);
static int session_pty_req(Session *);
/* import */
extern ServerOptions options;
extern char *__progname;
extern int log_stderr;
extern int debug_flag;
extern u_int utmp_len;
extern int startup_pipe;
extern void destroy_sensitive_data(void);
/* original command from peer. */
const char *original_command = NULL;
/* data */
#define MAX_SESSIONS 10
Session sessions[MAX_SESSIONS];
#ifdef WITH_AIXAUTHENTICATE
char *aixloginmsg;
#endif /* WITH_AIXAUTHENTICATE */
#ifdef HAVE_LOGIN_CAP
login_cap_t *lc;
#endif
/* 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(void *_pw)
{
struct passwd *pw = _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 passwd * pw)
{
Channel *nc;
int sock;
struct sockaddr_un sunaddr;
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_name = xmalloc(MAXPATHLEN);
auth_sock_dir = xmalloc(MAXPATHLEN);
strlcpy(auth_sock_dir, "/tmp/ssh-XXXXXXXX", MAXPATHLEN);
/* Create private directory for socket */
if (mkdtemp(auth_sock_dir) == NULL) {
packet_send_debug("Agent forwarding disabled: "
"mkdtemp() failed: %.100s", strerror(errno));
restore_uid();
xfree(auth_sock_name);
xfree(auth_sock_dir);
auth_sock_name = NULL;
auth_sock_dir = NULL;
return 0;
}
snprintf(auth_sock_name, MAXPATHLEN, "%s/agent.%ld",
auth_sock_dir, (long) getpid());
/* delete agent socket on fatal() */
fatal_add_cleanup(auth_sock_cleanup_proc, pw);
/* Create the socket. */
sock = socket(AF_UNIX, SOCK_STREAM, 0);
if (sock < 0)
packet_disconnect("socket: %.100s", strerror(errno));
/* Bind it to the name. */
memset(&sunaddr, 0, sizeof(sunaddr));
sunaddr.sun_family = AF_UNIX;
strlcpy(sunaddr.sun_path, auth_sock_name, sizeof(sunaddr.sun_path));
if (bind(sock, (struct sockaddr *) & sunaddr, sizeof(sunaddr)) < 0)
packet_disconnect("bind: %.100s", strerror(errno));
/* Restore the privileged uid. */
restore_uid();
/* Start listening on the socket. */
if (listen(sock, 5) < 0)
packet_disconnect("listen: %.100s", strerror(errno));
/* Allocate a channel for the authentication agent socket. */
nc = channel_new("auth socket",
SSH_CHANNEL_AUTH_SOCKET, sock, sock, -1,
CHAN_X11_WINDOW_DEFAULT, CHAN_X11_PACKET_DEFAULT,
0, "auth socket", 1);
strlcpy(nc->path, auth_sock_name, sizeof(nc->path));
return 1;
}
void
do_authenticated(Authctxt *authctxt)
{
setproctitle("%s", authctxt->pw->pw_name);
/*
* Cancel the alarm we set to limit the time taken for
* authentication.
*/
alarm(0);
if (startup_pipe != -1) {
close(startup_pipe);
startup_pipe = -1;
}
/* setup the channel layer */
if (!no_port_forwarding_flag && options.allow_tcp_forwarding)
channel_permit_all_opens();
if (compat20)
do_authenticated2(authctxt);
else
do_authenticated1(authctxt);
/* remove agent socket */
if (auth_sock_name != NULL)
auth_sock_cleanup_proc(authctxt->pw);
#ifdef KRB4
if (options.kerberos_ticket_cleanup)
krb4_cleanup_proc(authctxt);
#endif
#ifdef KRB5
if (options.kerberos_ticket_cleanup)
krb5_cleanup_proc(authctxt);
#endif
}
/*
* Prepares for an interactive session. This is called after the user has
* been successfully authenticated. During this message exchange, pseudo
* terminals are allocated, X11, TCP/IP, and authentication agent forwardings
* are requested, etc.
*/
static void
do_authenticated1(Authctxt *authctxt)
{
Session *s;
char *command;
int success, type, screen_flag;
int enable_compression_after_reply = 0;
u_int proto_len, data_len, dlen, compression_level = 0;
s = session_new();
s->authctxt = authctxt;
s->pw = authctxt->pw;
/*
* We stay in this loop until the client requests to execute a shell
* or a command.
*/
for (;;) {
success = 0;
/* Get a packet from the client. */
type = packet_read();
/* Process the packet. */
switch (type) {
case SSH_CMSG_REQUEST_COMPRESSION:
compression_level = packet_get_int();
packet_check_eom();
if (compression_level < 1 || compression_level > 9) {
packet_send_debug("Received illegal compression level %d.",
compression_level);
break;
}
if (!options.compression) {
debug2("compression disabled");
break;
}
/* Enable compression after we have responded with SUCCESS. */
enable_compression_after_reply = 1;
success = 1;
break;
case SSH_CMSG_REQUEST_PTY:
success = session_pty_req(s);
break;
case SSH_CMSG_X11_REQUEST_FORWARDING:
s->auth_proto = packet_get_string(&proto_len);
s->auth_data = packet_get_string(&data_len);
screen_flag = packet_get_protocol_flags() &
SSH_PROTOFLAG_SCREEN_NUMBER;
debug2("SSH_PROTOFLAG_SCREEN_NUMBER: %d", screen_flag);
if (packet_remaining() == 4) {
if (!screen_flag)
debug2("Buggy client: "
"X11 screen flag missing");
s->screen = packet_get_int();
} else {
s->screen = 0;
}
packet_check_eom();
success = session_setup_x11fwd(s);
if (!success) {
xfree(s->auth_proto);
xfree(s->auth_data);
s->auth_proto = NULL;
s->auth_data = NULL;
}
break;
case SSH_CMSG_AGENT_REQUEST_FORWARDING:
if (no_agent_forwarding_flag || compat13) {
debug("Authentication agent forwarding not permitted for this authentication.");
break;
}
debug("Received authentication agent forwarding request.");
success = auth_input_request_forwarding(s->pw);
break;
case SSH_CMSG_PORT_FORWARD_REQUEST:
if (no_port_forwarding_flag) {
debug("Port forwarding not permitted for this authentication.");
break;
}
if (!options.allow_tcp_forwarding) {
debug("Port forwarding not permitted.");
break;
}
debug("Received TCP/IP port forwarding request.");
channel_input_port_forward_request(s->pw->pw_uid == 0, options.gateway_ports);
success = 1;
break;
case SSH_CMSG_MAX_PACKET_SIZE:
if (packet_set_maxsize(packet_get_int()) > 0)
success = 1;
break;
#if defined(AFS) || defined(KRB5)
case SSH_CMSG_HAVE_KERBEROS_TGT:
if (!options.kerberos_tgt_passing) {
verbose("Kerberos TGT passing disabled.");
} else {
char *kdata = packet_get_string(&dlen);
packet_check_eom();
/* XXX - 0x41, see creds_to_radix version */
if (kdata[0] != 0x41) {
#ifdef KRB5
krb5_data tgt;
tgt.data = kdata;
tgt.length = dlen;
if (auth_krb5_tgt(s->authctxt, &tgt))
success = 1;
else
verbose("Kerberos v5 TGT refused for %.100s", s->authctxt->user);
#endif /* KRB5 */
} else {
#ifdef AFS
if (auth_krb4_tgt(s->authctxt, kdata))
success = 1;
else
verbose("Kerberos v4 TGT refused for %.100s", s->authctxt->user);
#endif /* AFS */
}
xfree(kdata);
}
break;
#endif /* AFS || KRB5 */
#ifdef AFS
case SSH_CMSG_HAVE_AFS_TOKEN:
if (!options.afs_token_passing || !k_hasafs()) {
verbose("AFS token passing disabled.");
} else {
/* Accept AFS token. */
char *token = packet_get_string(&dlen);
packet_check_eom();
if (auth_afs_token(s->authctxt, token))
success = 1;
else
verbose("AFS token refused for %.100s",
s->authctxt->user);
xfree(token);
}
break;
#endif /* AFS */
case SSH_CMSG_EXEC_SHELL:
case SSH_CMSG_EXEC_CMD:
if (type == SSH_CMSG_EXEC_CMD) {
command = packet_get_string(&dlen);
debug("Exec command '%.500s'", command);
do_exec(s, command);
xfree(command);
} else {
do_exec(s, NULL);
}
packet_check_eom();
session_close(s);
return;
default:
/*
* Any unknown messages in this phase are ignored,
* and a failure message is returned.
*/
logit("Unknown packet type received after authentication: %d", type);
}
packet_start(success ? SSH_SMSG_SUCCESS : SSH_SMSG_FAILURE);
packet_send();
packet_write_wait();
/* Enable compression now that we have replied if appropriate. */
if (enable_compression_after_reply) {
enable_compression_after_reply = 0;
packet_start_compression(compression_level);
}
}
}
/*
* 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.
*/
void
do_exec_no_pty(Session *s, const char *command)
{
pid_t pid;
#ifdef USE_PIPES
int pin[2], pout[2], perr[2];
/* Allocate pipes for communicating with the program. */
if (pipe(pin) < 0 || pipe(pout) < 0 || pipe(perr) < 0)
packet_disconnect("Could not create pipes: %.100s",
strerror(errno));
#else /* USE_PIPES */
int inout[2], err[2];
/* Uses socket pairs to communicate with the program. */
if (socketpair(AF_UNIX, SOCK_STREAM, 0, inout) < 0 ||
socketpair(AF_UNIX, SOCK_STREAM, 0, err) < 0)
packet_disconnect("Could not create socket pairs: %.100s",
strerror(errno));
#endif /* USE_PIPES */
if (s == NULL)
fatal("do_exec_no_pty: no session");
session_proctitle(s);
#if defined(USE_PAM)
if (options.use_pam) {
do_pam_session(s->pw->pw_name, NULL);
do_pam_setcred(1);
if (is_pam_password_change_required())
packet_disconnect("Password change required but no "
"TTY available");
}
#endif /* USE_PAM */
/* Fork the child. */
if ((pid = fork()) == 0) {
fatal_remove_all_cleanups();
/* Child. Reinitialize the log since the pid has changed. */
log_init(__progname, options.log_level, options.log_facility, log_stderr);
/*
* Create a new session and process group since the 4.4BSD
* setlogin() affects the entire process group.
*/
if (setsid() < 0)
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) < 0)
perror("dup2 stdin");
close(pin[0]);
/* Redirect stdout. */
close(pout[0]);
if (dup2(pout[1], 1) < 0)
perror("dup2 stdout");
close(pout[1]);
/* Redirect stderr. */
close(perr[0]);
if (dup2(perr[1], 2) < 0)
perror("dup2 stderr");
close(perr[1]);
#else /* USE_PIPES */
/*
* 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) < 0) /* stdin */
perror("dup2 stdin");
if (dup2(inout[0], 1) < 0) /* stdout. Note: same socket as stdin. */
perror("dup2 stdout");
if (dup2(err[0], 2) < 0) /* stderr */
perror("dup2 stderr");
#endif /* USE_PIPES */
#ifdef _UNICOS
cray_init_job(s->pw); /* set up cray jid and tmpdir */
#endif
/* Do processing for the child (exec command etc). */
do_child(s, command);
/* NOTREACHED */
}
#ifdef _UNICOS
signal(WJSIGNAL, cray_job_termination_handler);
#endif /* _UNICOS */
#ifdef HAVE_CYGWIN
if (is_winnt)
cygwin_set_impersonation_token(INVALID_HANDLE_VALUE);
#endif
if (pid < 0)
packet_disconnect("fork failed: %.100s", strerror(errno));
s->pid = pid;
/* Set interactive/non-interactive mode. */
packet_set_interactive(s->display != NULL);
#ifdef USE_PIPES
/* We are the parent. Close the child sides of the pipes. */
close(pin[0]);
close(pout[1]);
close(perr[1]);
if (compat20) {
session_set_fds(s, pin[1], pout[0], s->is_subsystem ? -1 : perr[0]);
} else {
/* Enter the interactive session. */
server_loop(pid, pin[1], pout[0], perr[0]);
/* server_loop has closed pin[1], pout[0], and perr[0]. */
}
#else /* USE_PIPES */
/* 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.
*/
if (compat20) {
session_set_fds(s, inout[1], inout[1], s->is_subsystem ? -1 : err[1]);
} else {
server_loop(pid, inout[1], inout[1], err[1]);
/* server_loop has closed inout[1] and err[1]. */
}
#endif /* USE_PIPES */
}
/*
* 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.
*/
void
do_exec_pty(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) {
do_pam_session(s->pw->pw_name, s->tty);
do_pam_setcred(1);
}
#endif
/* Fork the child. */
if ((pid = fork()) == 0) {
fatal_remove_all_cleanups();
/* Child. Reinitialize the log because the pid has changed. */
log_init(__progname, options.log_level, options.log_facility, log_stderr);
/* 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) < 0)
error("dup2 stdin: %s", strerror(errno));
if (dup2(ttyfd, 1) < 0)
error("dup2 stdout: %s", strerror(errno));
if (dup2(ttyfd, 2) < 0)
error("dup2 stderr: %s", strerror(errno));
/* Close the extra descriptor for the pseudo tty. */
close(ttyfd);
/* record login, etc. similar to login(1) */
#ifndef HAVE_OSF_SIA
if (!(options.use_login && command == NULL)) {
#ifdef _UNICOS
cray_init_job(s->pw); /* set up cray jid and tmpdir */
#endif /* _UNICOS */
do_login(s, command);
}
# ifdef LOGIN_NEEDS_UTMPX
else
do_pre_login(s);
# endif
#endif
/* Do common processing for the child, such as execing the command. */
do_child(s, command);
/* NOTREACHED */
}
#ifdef _UNICOS
signal(WJSIGNAL, cray_job_termination_handler);
#endif /* _UNICOS */
#ifdef HAVE_CYGWIN
if (is_winnt)
cygwin_set_impersonation_token(INVALID_HANDLE_VALUE);
#endif
if (pid < 0)
packet_disconnect("fork failed: %.100s", strerror(errno));
s->pid = pid;
/* Parent. Close the slave side of the pseudo tty. */
close(ttyfd);
/*
* 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.
*/
fdout = dup(ptyfd);
if (fdout < 0)
packet_disconnect("dup #1 failed: %.100s", strerror(errno));
/* we keep a reference to the pty master */
ptymaster = dup(ptyfd);
if (ptymaster < 0)
packet_disconnect("dup #2 failed: %.100s", strerror(errno));
s->ptymaster = ptymaster;
/* Enter interactive session. */
packet_set_interactive(1);
if (compat20) {
session_set_fds(s, ptyfd, fdout, -1);
} else {
server_loop(pid, ptyfd, fdout, -1);
/* server_loop _has_ closed ptyfd and fdout. */
}
}
#ifdef LOGIN_NEEDS_UTMPX
static void
do_pre_login(Session *s)
{
socklen_t fromlen;
struct sockaddr_storage from;
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 (packet_connection_is_on_socket()) {
if (getpeername(packet_get_connection_in(),
(struct sockaddr *) & from, &fromlen) < 0) {
debug("getpeername: %.100s", strerror(errno));
fatal_cleanup();
}
}
record_utmp_only(pid, s->tty, s->pw->pw_name,
get_remote_name_or_ip(utmp_len, options.use_dns),
(struct sockaddr *)&from, fromlen);
}
#endif
/*
* This is called to fork and execute a command. If another command is
* to be forced, execute that instead.
*/
void
do_exec(Session *s, const char *command)
{
if (forced_command) {
original_command = command;
command = forced_command;
debug("Forced command '%.900s'", command);
}
if (s->ttyfd != -1)
do_exec_pty(s, command);
else
do_exec_no_pty(s, command);
original_command = NULL;
}
/* administrative, login(1)-like work */
void
do_login(Session *s, const char *command)
{
char *time_string;
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 (packet_connection_is_on_socket()) {
if (getpeername(packet_get_connection_in(),
(struct sockaddr *) & from, &fromlen) < 0) {
debug("getpeername: %.100s", strerror(errno));
fatal_cleanup();
}
}
/* 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,
get_remote_name_or_ip(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 && is_pam_password_change_required()) {
print_pam_messages();
do_pam_chauthtok();
}
#endif
if (check_quietlogin(s, command))
return;
#ifdef USE_PAM
if (options.use_pam && !is_pam_password_change_required())
print_pam_messages();
#endif /* USE_PAM */
#ifdef WITH_AIXAUTHENTICATE
if (aixloginmsg && *aixloginmsg)
printf("%s\n", aixloginmsg);
#endif /* WITH_AIXAUTHENTICATE */
#ifndef NO_SSH_LASTLOG
if (options.print_lastlog && s->last_login_time != 0) {
time_string = ctime(&s->last_login_time);
if (strchr(time_string, '\n'))
*strchr(time_string, '\n') = 0;
if (strcmp(s->hostname, "") == 0)
printf("Last login: %s\r\n", time_string);
else
printf("Last login: %s from %s\r\n", time_string,
s->hostname);
}
#endif /* NO_SSH_LASTLOG */
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", "/etc/motd",
"/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;
}
/*
* Sets the value of the given variable in the environment. If the variable
* already exists, its value is overriden.
*/
static void
child_set_env(char ***envp, u_int *envsizep, const char *name,
const char *value)
{
u_int i, namelen;
char **env;
/*
* Find the slot where the value should be stored. If the variable
* already exists, we reuse the slot; otherwise we append a new slot
* at the end of the array, expanding if necessary.
*/
env = *envp;
namelen = strlen(name);
for (i = 0; env[i]; i++)
if (strncmp(env[i], name, namelen) == 0 && env[i][namelen] == '=')
break;
if (env[i]) {
/* Reuse the slot. */
xfree(env[i]);
} else {
/* New variable. Expand if necessary. */
if (i >= (*envsizep) - 1) {
if (*envsizep >= 1000)
fatal("child_set_env: too many env vars,"
" skipping: %.100s", name);
(*envsizep) += 50;
env = (*envp) = xrealloc(env, (*envsizep) * sizeof(char *));
}
/* Need to set the NULL pointer at end of array beyond the new slot. */
env[i + 1] = NULL;
}
/* Allocate space and format the variable in the appropriate slot. */
env[i] = xmalloc(strlen(name) + 1 + strlen(value) + 1);
snprintf(env[i], strlen(name) + 1 + strlen(value) + 1, "%s=%s", name, value);
}
/*
* 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.
*/
static void
read_environment_file(char ***env, u_int *envsize,
const char *filename)
{
FILE *f;
char buf[4096];
char *cp, *value;
u_int lineno = 0;
f = fopen(filename, "r");
if (!f)
return;
while (fgets(buf, sizeof(buf), f)) {
if (++lineno > 1000)
fatal("Too many lines in environment file %s", filename);
for (cp = buf; *cp == ' ' || *cp == '\t'; cp++)
;
if (!*cp || *cp == '#' || *cp == '\n')
continue;
if (strchr(cp, '\n'))
*strchr(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++;
child_set_env(env, envsize, cp, value);
}
fclose(f);
}
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) {
xfree(var_name);
continue;
}
*var_val++ = '\0';
debug3("Copy environment: %s=%s", var_name, var_val);
child_set_env(env, envsize, var_name, var_val);
xfree(var_name);
}
}
static char **
do_setup_env(Session *s, const char *shell)
{
char buf[256];
u_int i, envsize;
char **env, *laddr;
struct passwd *pw = s->pw;
/* Initialize the environment. */
envsize = 100;
env = xmalloc(envsize * sizeof(char *));
env[0] = NULL;
#ifdef HAVE_CYGWIN
/*
* The Windows environment contains some setting which are
* important for a running system. They must not be dropped.
*/
copy_environment(environ, &env, &envsize);
#endif
if (!options.use_login) {
/* Set basic environment. */
child_set_env(&env, &envsize, "USER", pw->pw_name);
child_set_env(&env, &envsize, "LOGNAME", pw->pw_name);
#ifdef _AIX
child_set_env(&env, &envsize, "LOGIN", pw->pw_name);
#endif
child_set_env(&env, &envsize, "HOME", pw->pw_dir);
#ifdef HAVE_LOGIN_CAP
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"));
#else /* HAVE_LOGIN_CAP */
# ifndef HAVE_CYGWIN
/*
* There's no standard path on Windows. The path contains
* important components pointing to the system directories,
* needed for loading shared libraries. So the path better
* remains intact here.
*/
# ifdef SUPERUSER_PATH
child_set_env(&env, &envsize, "PATH",
s->pw->pw_uid == 0 ? SUPERUSER_PATH : _PATH_STDPATH);
# else
child_set_env(&env, &envsize, "PATH", _PATH_STDPATH);
# endif /* SUPERUSER_PATH */
# endif /* HAVE_CYGWIN */
#endif /* HAVE_LOGIN_CAP */
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"));
/* Set custom environment options from RSA authentication. */
if (!options.use_login) {
while (custom_environment) {
struct envstring *ce = custom_environment;
char *str = ce->s;
for (i = 0; str[i] != '=' && str[i]; i++)
;
if (str[i] == '=') {
str[i] = 0;
child_set_env(&env, &envsize, str, str + i + 1);
}
custom_environment = ce->next;
xfree(ce->s);
xfree(ce);
}
}
/* SSH_CLIENT deprecated */
snprintf(buf, sizeof buf, "%.50s %d %d",
get_remote_ipaddr(), get_remote_port(), get_local_port());
child_set_env(&env, &envsize, "SSH_CLIENT", buf);
laddr = get_local_ipaddr(packet_get_connection_in());
snprintf(buf, sizeof buf, "%.50s %d %.50s %d",
get_remote_ipaddr(), get_remote_port(), laddr, get_local_port());
xfree(laddr);
child_set_env(&env, &envsize, "SSH_CONNECTION", buf);
if (s->ttyfd != -1)
child_set_env(&env, &envsize, "SSH_TTY", s->tty);
if (s->term)
child_set_env(&env, &envsize, "TERM", s->term);
if (s->display)
child_set_env(&env, &envsize, "DISPLAY", s->display);
if (original_command)
child_set_env(&env, &envsize, "SSH_ORIGINAL_COMMAND",
original_command);
#ifdef _UNICOS
if (cray_tmpdir[0] != '\0')
child_set_env(&env, &envsize, "TMPDIR", cray_tmpdir);
#endif /* _UNICOS */
#ifdef _AIX
{
char *cp;
if ((cp = getenv("AUTHSTATE")) != NULL)
child_set_env(&env, &envsize, "AUTHSTATE", cp);
if ((cp = getenv("KRB5CCNAME")) != NULL)
child_set_env(&env, &envsize, "KRB5CCNAME", cp);
read_environment_file(&env, &envsize, "/etc/environment");
}
#endif
#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 = fetch_pam_environment();
copy_environment(p, &env, &envsize);
free_pam_environment(p);
}
#endif /* USE_PAM */
if (auth_sock_name != NULL)
child_set_env(&env, &envsize, SSH_AUTHSOCKET_ENV_NAME,
auth_sock_name);
/* read $HOME/.ssh/environment. */
if (options.permit_user_env && !options.use_login) {
snprintf(buf, sizeof buf, "%.200s/.ssh/environment",
strcmp(pw->pw_dir, "/") ? pw->pw_dir : "");
read_environment_file(&env, &envsize, buf);
}
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(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 */
if (!s->is_subsystem && (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];
#ifdef HAVE_LOGIN_CAP
if (!login_getcapbool(lc, "ignorenologin", 0) && pw->pw_uid)
f = fopen(login_getcapstr(lc, "nologin", _PATH_NOLOGIN,
_PATH_NOLOGIN), "r");
#else
if (pw->pw_uid)
f = fopen(_PATH_NOLOGIN, "r");
#endif
if (f) {
/* /etc/nologin exists. Print its contents and exit. */
logit("User %.100s not allowed because %s exists",
pw->pw_name, _PATH_NOLOGIN);
while (fgets(buf, sizeof(buf), f))
fputs(buf, stderr);
fclose(f);
fflush(NULL);
exit(254);
}
}
/* Set login name, uid, gid, and groups. */
void
do_setusercontext(struct passwd *pw)
{
#ifndef HAVE_CYGWIN
if (getuid() == 0 || geteuid() == 0)
#endif /* HAVE_CYGWIN */
{
#ifdef HAVE_SETPCRED
setpcred(pw->pw_name);
#endif /* HAVE_SETPCRED */
#ifdef HAVE_LOGIN_CAP
# ifdef __bsdi__
setpgid(0, 0);
# endif
if (setusercontext(lc, pw, pw->pw_uid,
(LOGIN_SETALL & ~LOGIN_SETPATH)) < 0) {
perror("unable to set user context");
exit(1);
}
#else
# if defined(HAVE_GETLUID) && defined(HAVE_SETLUID)
/* Sets login uid for accounting */
if (getluid() == -1 && setluid(pw->pw_uid) == -1)
error("setluid: %s", strerror(errno));
# endif /* defined(HAVE_GETLUID) && defined(HAVE_SETLUID) */
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(0);
# endif /* USE_PAM */
# if defined(WITH_IRIX_PROJECT) || defined(WITH_IRIX_JOBS) || defined(WITH_IRIX_ARRAY)
irix_setusercontext(pw);
# endif /* defined(WITH_IRIX_PROJECT) || defined(WITH_IRIX_JOBS) || defined(WITH_IRIX_ARRAY) */
# ifdef _AIX
aix_usrinfo(pw);
# endif /* _AIX */
/* Permanently switch to the desired uid. */
permanently_set_uid(pw);
#endif
}
#ifdef HAVE_CYGWIN
if (is_winnt)
#endif
if (getuid() != pw->pw_uid || geteuid() != pw->pw_uid)
fatal("Failed to set uids to %u.", (u_int) pw->pw_uid);
}
static void
launch_login(struct passwd *pw, const char *hostname)
{
/* Launch login(1). */
execl(LOGIN_PROGRAM, "login", "-h", hostname,
#ifdef xxxLOGIN_NEEDS_TERM
(s->term ? s->term : "unknown"),
#endif /* LOGIN_NEEDS_TERM */
#ifdef LOGIN_NO_ENDOPT
"-p", "-f", pw->pw_name, (char *)NULL);
#else
"-p", "-f", "--", pw->pw_name, (char *)NULL);
#endif
/* Login couldn't be executed, die. */
perror("login");
exit(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.
*/
void
do_child(Session *s, const char *command)
{
extern char **environ;
char **env;
char *argv[10];
const char *shell, *shell0, *hostname = NULL;
struct passwd *pw = s->pw;
u_int i;
/* remove hostkey from the child's memory */
destroy_sensitive_data();
/* login(1) is only called if we execute the login shell */
if (options.use_login && command != NULL)
options.use_login = 0;
#ifdef _UNICOS
cray_setup(pw->pw_uid, pw->pw_name, command);
#endif /* _UNICOS */
/*
* Login(1) does this as well, and it needs uid 0 for the "-h"
* switch, so we let login(1) to this for us.
*/
if (!options.use_login) {
#ifdef HAVE_OSF_SIA
session_setup_sia(pw, s->ttyfd == -1 ? NULL : s->tty);
if (!check_quietlogin(s, command))
do_motd();
#else /* HAVE_OSF_SIA */
do_nologin(pw);
do_setusercontext(pw);
#endif /* HAVE_OSF_SIA */
}
/*
* 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(s, shell);
#ifdef HAVE_LOGIN_CAP
shell = login_getcapstr(lc, "shell", (char *)shell, (char *)shell);
#endif
/* we have to stash the hostname before we close our socket. */
if (options.use_login)
hostname = get_remote_name_or_ip(utmp_len,
options.use_dns);
/*
* 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
* get_remote_ipaddr there.
*/
if (packet_get_connection_in() == packet_get_connection_out())
close(packet_get_connection_in());
else {
close(packet_get_connection_in());
close(packet_get_connection_out());
}
/*
* Close all descriptors related to channels. They will still remain
* open in the parent.
*/
/* XXX better use close-on-exec? -markus */
channel_close_all();
/*
* 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.
*/
for (i = 3; i < 64; i++)
close(i);
/*
* Must take new environment into use so that .ssh/rc,
* /etc/ssh/sshrc and xauth are run in the proper environment.
*/
environ = env;
#ifdef AFS
/* Try to get AFS tokens for the local cell. */
if (k_hasafs()) {
char cell[64];
if (k_afs_cell_of_file(pw->pw_dir, cell, sizeof(cell)) == 0)
krb_afslog(cell, 0);
krb_afslog(0, 0);
}
#endif /* AFS */
/* Change current directory to the user\'s home directory. */
if (chdir(pw->pw_dir) < 0) {
fprintf(stderr, "Could not chdir to home directory %s: %s\n",
pw->pw_dir, strerror(errno));
#ifdef HAVE_LOGIN_CAP
if (login_getcapbool(lc, "requirehome", 0))
exit(1);
#endif
}
if (!options.use_login)
do_rc_files(s, shell);
/* restore SIGPIPE for child */
signal(SIGPIPE, SIG_DFL);
if (options.use_login) {
launch_login(pw, hostname);
/* NEVERREACHED */
}
/* 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] = (char *) shell0;
argv[1] = "-c";
argv[2] = (char *) command;
argv[3] = NULL;
execve(shell, argv, env);
perror(shell);
exit(1);
}
Session *
session_new(void)
{
int i;
static int did_init = 0;
if (!did_init) {
debug("session_new: init");
for (i = 0; i < MAX_SESSIONS; i++) {
sessions[i].used = 0;
}
did_init = 1;
}
for (i = 0; i < MAX_SESSIONS; i++) {
Session *s = &sessions[i];
if (! s->used) {
memset(s, 0, sizeof(*s));
s->chanid = -1;
s->ptyfd = -1;
s->ttyfd = -1;
s->used = 1;
s->self = i;
debug("session_new: session %d", i);
return s;
}
}
return NULL;
}
static void
session_dump(void)
{
int i;
for (i = 0; i < MAX_SESSIONS; i++) {
Session *s = &sessions[i];
debug("dump: used %d session %d %p channel %d pid %ld",
s->used,
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)
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 < MAX_SESSIONS; 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 < MAX_SESSIONS; 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_pid(pid_t pid)
{
int i;
debug("session_by_pid: pid %ld", (long)pid);
for (i = 0; i < MAX_SESSIONS; 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(Session *s)
{
s->col = packet_get_int();
s->row = packet_get_int();
s->xpixel = packet_get_int();
s->ypixel = packet_get_int();
packet_check_eom();
pty_change_window_size(s->ptyfd, s->row, s->col, s->xpixel, s->ypixel);
return 1;
}
static int
session_pty_req(Session *s)
{
u_int len;
int n_bytes;
if (no_pty_flag) {
debug("Allocating a pty not permitted for this authentication.");
return 0;
}
if (s->ttyfd != -1) {
packet_disconnect("Protocol error: you already have a pty.");
return 0;
}
/* Get the time and hostname when the user last logged in. */
if (options.print_lastlog) {
s->hostname[0] = '\0';
s->last_login_time = get_last_login_time(s->pw->pw_uid,
s->pw->pw_name, s->hostname, sizeof(s->hostname));
}
s->term = packet_get_string(&len);
if (compat20) {
s->col = packet_get_int();
s->row = packet_get_int();
} else {
s->row = packet_get_int();
s->col = packet_get_int();
}
s->xpixel = packet_get_int();
s->ypixel = packet_get_int();
if (strcmp(s->term, "") == 0) {
xfree(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)))) {
if (s->term)
xfree(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);
/* for SSH1 the tty modes length is not given */
if (!compat20)
n_bytes = packet_remaining();
tty_parse_modes(s->ttyfd, &n_bytes);
/*
* Add a cleanup function to clear the utmp entry and record logout
* time in case we call fatal() (e.g., the connection gets closed).
*/
fatal_add_cleanup(session_pty_cleanup, (void *)s);
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);
packet_check_eom();
session_proctitle(s);
return 1;
}
static int
session_subsystem_req(Session *s)
{
struct stat st;
u_int len;
int success = 0;
char *cmd, *subsys = packet_get_string(&len);
int i;
packet_check_eom();
logit("subsystem request for %.100s", subsys);
for (i = 0; i < options.num_subsystems; i++) {
if (strcmp(subsys, options.subsystem_name[i]) == 0) {
cmd = options.subsystem_command[i];
if (stat(cmd, &st) < 0) {
error("subsystem: cannot stat %s: %s", cmd,
strerror(errno));
break;
}
debug("subsystem: exec() %s", cmd);
s->is_subsystem = 1;
do_exec(s, cmd);
success = 1;
break;
}
}
if (!success)
logit("subsystem request for %.100s failed, subsystem not found",
subsys);
xfree(subsys);
return success;
}
static int
session_x11_req(Session *s)
{
int success;
s->single_connection = packet_get_char();
s->auth_proto = packet_get_string(NULL);
s->auth_data = packet_get_string(NULL);
s->screen = packet_get_int();
packet_check_eom();
success = session_setup_x11fwd(s);
if (!success) {
xfree(s->auth_proto);
xfree(s->auth_data);
s->auth_proto = NULL;
s->auth_data = NULL;
}
return success;
}
static int
session_shell_req(Session *s)
{
packet_check_eom();
do_exec(s, NULL);
return 1;
}
static int
session_exec_req(Session *s)
{
u_int len;
char *command = packet_get_string(&len);
packet_check_eom();
do_exec(s, command);
xfree(command);
return 1;
}
static int
session_break_req(Session *s)
{
u_int break_length;
break_length = packet_get_int();
packet_check_eom();
if (s->ttyfd == -1)
return 0;
/* we will sleep from 500ms to 3000ms */
break_length = MIN(break_length, 3000);
break_length = MAX(break_length, 500);
ioctl(s->ttyfd, TIOCSBRK, NULL);
/* should we care about EINTR? */
usleep(break_length * 1000);
ioctl(s->ttyfd, TIOCCBRK, NULL);
return 1;
}
static int
session_auth_agent_req(Session *s)
{
static int called = 0;
packet_check_eom();
if (no_agent_forwarding_flag) {
debug("session_auth_agent_req: no_agent_forwarding_flag");
return 0;
}
if (called) {
return 0;
} else {
called = 1;
return auth_input_request_forwarding(s->pw);
}
}
int
session_input_channel_req(Channel *c, const char *rtype)
{
int success = 0;
Session *s;
if ((s = session_by_channel(c->self)) == NULL) {
logit("session_input_channel_req: no session %d req %.100s",
c->self, rtype);
return 0;
}
debug("session_input_channel_req: session %d req %s", 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(s);
} else if (strcmp(rtype, "exec") == 0) {
success = session_exec_req(s);
} else if (strcmp(rtype, "pty-req") == 0) {
success = session_pty_req(s);
} else if (strcmp(rtype, "x11-req") == 0) {
success = session_x11_req(s);
} else if (strcmp(rtype, "auth-agent-req@openssh.com") == 0) {
success = session_auth_agent_req(s);
} else if (strcmp(rtype, "subsystem") == 0) {
success = session_subsystem_req(s);
} else if (strcmp(rtype, "break") == 0) {
success = session_break_req(s);
}
}
if (strcmp(rtype, "window-change") == 0) {
success = session_window_change_req(s);
}
return success;
}
void
session_set_fds(Session *s, int fdin, int fdout, int fderr)
{
if (!compat20)
fatal("session_set_fds: called for proto != 2.0");
/*
* 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);
channel_set_fds(s->chanid,
fdout, fdin, fderr,
fderr == -1 ? CHAN_EXTENDED_IGNORE : CHAN_EXTENDED_READ,
1,
CHAN_SES_WINDOW_DEFAULT);
}
/*
* Function to perform pty cleanup. Also called if we get aborted abnormally
* (e.g., due to a dropped connection).
*/
void
session_pty_cleanup2(void *session)
{
Session *s = session;
if (s == NULL) {
error("session_pty_cleanup: no session");
return;
}
if (s->ttyfd == -1)
return;
debug("session_pty_cleanup: session %d release %s", s->self, s->tty);
/* Record that the user has logged out. */
if (s->pid != 0)
record_logout(s->pid, s->tty, s->pw->pw_name);
/* 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 (close(s->ptymaster) < 0)
error("close(s->ptymaster/%d): %s", s->ptymaster, strerror(errno));
/* unlink pty from session */
s->ttyfd = -1;
}
void
session_pty_cleanup(void *session)
{
PRIVSEP(session_pty_cleanup2(session));
}
static 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_exit_message(Session *s, int status)
{
Channel *c;
if ((c = channel_lookup(s->chanid)) == NULL)
fatal("session_exit_message: session %d: no channel %d",
s->self, s->chanid);
debug("session_exit_message: session %d channel %d pid %ld",
s->self, s->chanid, (long)s->pid);
if (WIFEXITED(status)) {
channel_request_start(s->chanid, "exit-status", 0);
packet_put_int(WEXITSTATUS(status));
packet_send();
} else if (WIFSIGNALED(status)) {
channel_request_start(s->chanid, "exit-signal", 0);
packet_put_cstring(sig2name(WTERMSIG(status)));
#ifdef WCOREDUMP
packet_put_char(WCOREDUMP(status));
#else /* WCOREDUMP */
packet_put_char(0);
#endif /* WCOREDUMP */
packet_put_cstring("");
packet_put_cstring("");
packet_send();
} else {
/* Some weird exit cause. Just exit. */
packet_disconnect("wait returned status %04x.", status);
}
/* disconnect channel */
debug("session_exit_message: release channel %d", s->chanid);
channel_cancel_cleanup(s->chanid);
/*
* 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(c);
s->chanid = -1;
}
void
session_close(Session *s)
{
debug("session_close: session %d pid %ld", s->self, (long)s->pid);
if (s->ttyfd != -1) {
fatal_remove_cleanup(session_pty_cleanup, (void *)s);
session_pty_cleanup(s);
}
if (s->term)
xfree(s->term);
if (s->display)
xfree(s->display);
if (s->auth_display)
xfree(s->auth_display);
if (s->auth_data)
xfree(s->auth_data);
if (s->auth_proto)
xfree(s->auth_proto);
s->used = 0;
session_proctitle(s);
}
void
session_close_by_pid(pid_t pid, int status)
{
Session *s = session_by_pid(pid);
if (s == NULL) {
debug("session_close_by_pid: no session for pid %ld",
(long)pid);
return;
}
if (s->chanid != -1)
session_exit_message(s, status);
session_close(s);
}
/*
* this is called when a channel dies before
* the session 'child' itself dies
*/
void
session_close_by_channel(int id, void *arg)
{
Session *s = session_by_channel(id);
if (s == NULL) {
debug("session_close_by_channel: no session for id %d", id);
return;
}
debug("session_close_by_channel: channel %d child %ld",
id, (long)s->pid);
if (s->pid != 0) {
debug("session_close_by_channel: channel %d: has child", id);
/*
* delay detach of session, but release pty, since
* the fd's to the child are already closed
*/
if (s->ttyfd != -1) {
fatal_remove_cleanup(session_pty_cleanup, (void *)s);
session_pty_cleanup(s);
}
return;
}
/* detach by removing callback */
channel_cancel_cleanup(s->chanid);
s->chanid = -1;
session_close(s);
}
void
session_destroy_all(void (*closefunc)(Session *))
{
int i;
for (i = 0; i < MAX_SESSIONS; i++) {
Session *s = &sessions[i];
if (s->used) {
if (closefunc != NULL)
closefunc(s);
else
session_close(s);
}
}
}
static char *
session_tty_list(void)
{
static char buf[1024];
int i;
char *cp;
buf[0] = '\0';
for (i = 0; i < MAX_SESSIONS; i++) {
Session *s = &sessions[i];
if (s->used && s->ttyfd != -1) {
if (strncmp(s->tty, "/dev/", 5) != 0) {
cp = strrchr(s->tty, '/');
cp = (cp == NULL) ? s->tty : cp + 1;
} else
cp = s->tty + 5;
if (buf[0] != '\0')
strlcat(buf, ",", sizeof buf);
strlcat(buf, cp, 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(Session *s)
{
struct stat st;
char display[512], auth_display[512];
char hostname[MAXHOSTNAMELEN];
if (no_x11_forwarding_flag) {
packet_send_debug("X11 forwarding disabled in user configuration file.");
return 0;
}
if (!options.x11_forwarding) {
debug("X11 forwarding disabled in server configuration file.");
return 0;
}
if (!options.xauth_location ||
(stat(options.xauth_location, &st) == -1)) {
packet_send_debug("No xauth program; cannot forward with spoofing.");
return 0;
}
if (options.use_login) {
packet_send_debug("X11 forwarding disabled; "
"not compatible with UseLogin=yes.");
return 0;
}
if (s->display != NULL) {
debug("X11 display already set.");
return 0;
}
if (x11_create_display_inet(options.x11_display_offset,
options.x11_use_localhost, s->single_connection,
&s->display_number) == -1) {
debug("x11_create_display_inet failed.");
return 0;
}
/* Set up a suitable value for the DISPLAY variable. */
if (gethostname(hostname, sizeof(hostname)) < 0)
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 {
#ifdef IPADDR_IN_DISPLAY
struct hostent *he;
struct in_addr my_addr;
he = gethostbyname(hostname);
if (he == NULL) {
error("Can't get IP address for X11 DISPLAY.");
packet_send_debug("Can't get IP address for X11 DISPLAY.");
return 0;
}
memcpy(&my_addr, he->h_addr_list[0], sizeof(struct in_addr));
snprintf(display, sizeof display, "%.50s:%u.%u", inet_ntoa(my_addr),
s->display_number, s->screen);
#else
snprintf(display, sizeof display, "%.400s:%u.%u", hostname,
s->display_number, s->screen);
#endif
s->display = xstrdup(display);
s->auth_display = xstrdup(display);
}
return 1;
}
static void
do_authenticated2(Authctxt *authctxt)
{
server_loop2(authctxt);
}
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