File: [local] / src / usr.bin / ssh / session.c (download)
Revision 1.74, Tue Apr 17 19:34:25 2001 UTC (23 years, 1 month ago) by markus
Branch: MAIN
CVS Tags: OPENBSD_2_9_BASE
Branch point for: OPENBSD_2_9
Changes since 1.73: +13 -10 lines
move auth_approval to do_authenticated().
do_child(): nuke hostkeys from memory
don't source .ssh/rc for subsystems.
|
/*
* 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 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 1.74 2001/04/17 19:34:25 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 "nchan.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"
/* types */
#define TTYSZ 64
typedef struct Session Session;
struct Session {
int used;
int self;
struct passwd *pw;
pid_t pid;
/* tty */
char *term;
int ptyfd, ttyfd, ptymaster;
int row, col, xpixel, ypixel;
char tty[TTYSZ];
/* X11 */
char *display;
int screen;
char *auth_proto;
char *auth_data;
int single_connection;
/* proto 2 */
int chanid;
int is_subsystem;
};
/* func */
Session *session_new(void);
void session_set_fds(Session *s, int fdin, int fdout, int fderr);
void session_pty_cleanup(Session *s);
void session_proctitle(Session *s);
void do_exec_pty(Session *s, const char *command);
void do_exec_no_pty(Session *s, const char *command);
void do_login(Session *s, const char *command);
void do_child(Session *s, const char *command);
void do_motd(void);
int check_quietlogin(Session *s, const char *command);
void do_authenticated1(Authctxt *authctxt);
void do_authenticated2(Authctxt *authctxt);
/* 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);
/* Local Xauthority file. */
static char *xauthfile;
/* original command from peer. */
char *original_command = NULL;
/* data */
#define MAX_SESSIONS 10
Session sessions[MAX_SESSIONS];
#ifdef HAVE_LOGIN_CAP
static login_cap_t *lc;
#endif
void
do_authenticated(Authctxt *authctxt)
{
/*
* Cancel the alarm we set to limit the time taken for
* authentication.
*/
alarm(0);
if (startup_pipe != -1) {
close(startup_pipe);
startup_pipe = -1;
}
#ifdef HAVE_LOGIN_CAP
if ((lc = login_getclass(authctxt->pw->pw_class)) == NULL) {
error("unable to get login class");
return;
}
#ifdef BSD_AUTH
if (auth_approval(NULL, lc, authctxt->pw->pw_name, "ssh") <= 0) {
packet_disconnect("Approval failure for %s",
authctxt->pw->pw_name);
}
#endif
#endif
/* 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 local Xauthority file.
*/
void
xauthfile_cleanup_proc(void *ignore)
{
debug("xauthfile_cleanup_proc called");
if (xauthfile != NULL) {
char *p;
unlink(xauthfile);
p = strrchr(xauthfile, '/');
if (p != NULL) {
*p = '\0';
rmdir(xauthfile);
}
xfree(xauthfile);
xauthfile = NULL;
}
}
/*
* Function to perform cleanup if we get aborted abnormally (e.g., due to a
* dropped connection).
*/
void
pty_cleanup_proc(void *session)
{
Session *s=session;
if (s == NULL)
fatal("pty_cleanup_proc: no session");
debug("pty_cleanup_proc: %s", s->tty);
if (s->pid != 0) {
/* Record that the user has logged out. */
record_logout(s->pid, s->tty);
}
/* Release the pseudo-tty. */
pty_release(s->tty);
}
/*
* 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.
*/
void
do_authenticated1(Authctxt *authctxt)
{
Session *s;
char *command;
int success, type, fd, n_bytes, plen, screen_flag, have_pty = 0;
int compression_level = 0, enable_compression_after_reply = 0;
u_int proto_len, data_len, dlen;
s = session_new();
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(&plen);
/* Process the packet. */
switch (type) {
case SSH_CMSG_REQUEST_COMPRESSION:
packet_integrity_check(plen, 4, type);
compression_level = packet_get_int();
if (compression_level < 1 || compression_level > 9) {
packet_send_debug("Received illegal compression level %d.",
compression_level);
break;
}
/* Enable compression after we have responded with SUCCESS. */
enable_compression_after_reply = 1;
success = 1;
break;
case SSH_CMSG_REQUEST_PTY:
if (no_pty_flag) {
debug("Allocating a pty not permitted for this authentication.");
break;
}
if (have_pty)
packet_disconnect("Protocol error: you already have a pty.");
debug("Allocating pty.");
/* Allocate a pty and open it. */
if (!pty_allocate(&s->ptyfd, &s->ttyfd, s->tty,
sizeof(s->tty))) {
error("Failed to allocate pty.");
break;
}
fatal_add_cleanup(pty_cleanup_proc, (void *)s);
pty_setowner(s->pw, s->tty);
/* Get TERM from the packet. Note that the value may be of arbitrary length. */
s->term = packet_get_string(&dlen);
packet_integrity_check(dlen, strlen(s->term), type);
/* packet_integrity_check(plen, 4 + dlen + 4*4 + n_bytes, type); */
/* Remaining bytes */
n_bytes = plen - (4 + dlen + 4 * 4);
if (strcmp(s->term, "") == 0) {
xfree(s->term);
s->term = NULL;
}
/* Get window size from the packet. */
s->row = packet_get_int();
s->col = packet_get_int();
s->xpixel = packet_get_int();
s->ypixel = packet_get_int();
pty_change_window_size(s->ptyfd, s->row, s->col, s->xpixel, s->ypixel);
/* Get tty modes from the packet. */
tty_parse_modes(s->ttyfd, &n_bytes);
packet_integrity_check(plen, 4 + dlen + 4 * 4 + n_bytes, type);
session_proctitle(s);
/* Indicate that we now have a pty. */
success = 1;
have_pty = 1;
break;
case SSH_CMSG_X11_REQUEST_FORWARDING:
if (!options.x11_forwarding) {
packet_send_debug("X11 forwarding disabled in server configuration file.");
break;
}
if (!options.xauth_location) {
packet_send_debug("No xauth program; cannot forward with spoofing.");
break;
}
if (no_x11_forwarding_flag) {
packet_send_debug("X11 forwarding not permitted for this authentication.");
break;
}
debug("Received request for X11 forwarding with auth spoofing.");
if (s->display != NULL)
packet_disconnect("Protocol error: X11 display already set.");
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");
packet_integrity_check(plen,
4 + proto_len + 4 + data_len + 4, type);
s->screen = packet_get_int();
} else {
packet_integrity_check(plen,
4 + proto_len + 4 + data_len, type);
s->screen = 0;
}
s->display = x11_create_display_inet(s->screen, options.x11_display_offset);
if (s->display == NULL)
break;
/* Setup to always have a local .Xauthority. */
xauthfile = xmalloc(MAXPATHLEN);
strlcpy(xauthfile, "/tmp/ssh-XXXXXXXX", MAXPATHLEN);
temporarily_use_uid(s->pw);
if (mkdtemp(xauthfile) == NULL) {
restore_uid();
error("private X11 dir: mkdtemp %s failed: %s",
xauthfile, strerror(errno));
xfree(xauthfile);
xauthfile = NULL;
/* XXXX remove listening channels */
break;
}
strlcat(xauthfile, "/cookies", MAXPATHLEN);
fd = open(xauthfile, O_RDWR|O_CREAT|O_EXCL, 0600);
if (fd >= 0)
close(fd);
restore_uid();
fatal_add_cleanup(xauthfile_cleanup_proc, NULL);
success = 1;
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;
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);
packet_integrity_check(plen, 4 + dlen, type);
} else {
command = NULL;
packet_integrity_check(plen, 0, type);
}
if (forced_command != NULL) {
original_command = command;
command = forced_command;
debug("Forced command '%.500s'", forced_command);
}
if (have_pty)
do_exec_pty(s, command);
else
do_exec_no_pty(s, command);
if (command != NULL)
xfree(command);
/* Cleanup user's local Xauthority file. */
if (xauthfile)
xauthfile_cleanup_proc(NULL);
return;
default:
/*
* Any unknown messages in this phase are ignored,
* and a failure message is returned.
*/
log("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)
{
int 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);
/* Fork the child. */
if ((pid = fork()) == 0) {
/* 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 */
/* Do processing for the child (exec command etc). */
do_child(s, command);
/* NOTREACHED */
}
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;
/* Fork the child. */
if ((pid = fork()) == 0) {
/* 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 from the pseudo tty. */
if (dup2(ttyfd, fileno(stdin)) < 0)
error("dup2 stdin failed: %.100s", strerror(errno));
/* Redirect stdout to the pseudo tty. */
if (dup2(ttyfd, fileno(stdout)) < 0)
error("dup2 stdin failed: %.100s", strerror(errno));
/* Redirect stderr to the pseudo tty. */
if (dup2(ttyfd, fileno(stderr)) < 0)
error("dup2 stdin failed: %.100s", strerror(errno));
/* Close the extra descriptor for the pseudo tty. */
close(ttyfd);
/* record login, etc. similar to login(1) */
if (!(options.use_login && command == NULL))
do_login(s, command);
/* Do common processing for the child, such as execing the command. */
do_child(s, command);
/* NOTREACHED */
}
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. */
session_pty_cleanup(s);
}
}
/* administrative, login(1)-like work */
void
do_login(Session *s, const char *command)
{
char *time_string;
char hostname[MAXHOSTNAMELEN];
socklen_t fromlen;
struct sockaddr_storage from;
time_t last_login_time;
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));
if (packet_connection_is_on_socket()) {
fromlen = sizeof(from);
if (getpeername(packet_get_connection_in(),
(struct sockaddr *) & from, &fromlen) < 0) {
debug("getpeername: %.100s", strerror(errno));
fatal_cleanup();
}
}
/* Get the time and hostname when the user last logged in. */
if (options.print_lastlog) {
hostname[0] = '\0';
last_login_time = get_last_login_time(pw->pw_uid, pw->pw_name,
hostname, sizeof(hostname));
}
/* Record that there was a login on that tty from the remote host. */
record_login(pid, s->tty, pw->pw_name, pw->pw_uid,
get_remote_name_or_ip(utmp_len, options.reverse_mapping_check),
(struct sockaddr *)&from);
if (check_quietlogin(s, command))
return;
if (options.print_lastlog && last_login_time != 0) {
time_string = ctime(&last_login_time);
if (strchr(time_string, '\n'))
*strchr(time_string, '\n') = 0;
if (strcmp(hostname, "") == 0)
printf("Last login: %s\r\n", time_string);
else
printf("Last login: %s from %s\r\n", time_string, hostname);
}
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.
*/
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) {
(*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.
*/
void
read_environment_file(char ***env, u_int *envsize,
const char *filename)
{
FILE *f;
char buf[4096];
char *cp, *value;
f = fopen(filename, "r");
if (!f)
return;
while (fgets(buf, sizeof(buf), f)) {
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 in %.100s: %.200s\n", filename, buf);
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);
}
/*
* 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)
{
const char *shell, *hostname = NULL, *cp = NULL;
struct passwd * pw = s->pw;
char buf[256];
char cmd[1024];
FILE *f = NULL;
u_int envsize, i;
char **env;
extern char **environ;
struct stat st;
char *argv[10];
int do_xauth = s->auth_proto != NULL && s->auth_data != NULL;
/* 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;
if (!options.use_login) {
#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. */
while (fgets(buf, sizeof(buf), f))
fputs(buf, stderr);
fclose(f);
exit(254);
}
}
/* Set login name, uid, gid, and groups. */
/* 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) {
if (getuid() == 0 || geteuid() == 0) {
#ifdef HAVE_LOGIN_CAP
if (setusercontext(lc, pw, pw->pw_uid,
(LOGIN_SETALL & ~LOGIN_SETPATH)) < 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();
/* Permanently switch to the desired uid. */
permanently_set_uid(pw);
#endif
}
if (getuid() != pw->pw_uid || geteuid() != pw->pw_uid)
fatal("Failed to set uids to %u.", (u_int) pw->pw_uid);
}
/*
* 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;
#ifdef HAVE_LOGIN_CAP
shell = login_getcapstr(lc, "shell", (char *)shell, (char *)shell);
#endif
#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 */
/* Initialize the environment. */
envsize = 100;
env = xmalloc(envsize * sizeof(char *));
env[0] = NULL;
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);
child_set_env(&env, &envsize, "HOME", pw->pw_dir);
#ifdef HAVE_LOGIN_CAP
(void) setusercontext(lc, pw, pw->pw_uid, LOGIN_SETPATH);
child_set_env(&env, &envsize, "PATH", getenv("PATH"));
#else
child_set_env(&env, &envsize, "PATH", _PATH_STDPATH);
#endif
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. */
while (custom_environment) {
struct envstring *ce = custom_environment;
char *s = ce->s;
int i;
for (i = 0; s[i] != '=' && s[i]; i++);
if (s[i] == '=') {
s[i] = 0;
child_set_env(&env, &envsize, s, s + i + 1);
}
custom_environment = ce->next;
xfree(ce->s);
xfree(ce);
}
snprintf(buf, sizeof buf, "%.50s %d %d",
get_remote_ipaddr(), get_remote_port(), get_local_port());
child_set_env(&env, &envsize, "SSH_CLIENT", 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 KRB4
{
extern char *ticket;
if (ticket)
child_set_env(&env, &envsize, "KRBTKFILE", ticket);
}
#endif /* KRB4 */
if (xauthfile)
child_set_env(&env, &envsize, "XAUTHORITY", xauthfile);
if (auth_get_socket_name() != NULL)
child_set_env(&env, &envsize, SSH_AUTHSOCKET_ENV_NAME,
auth_get_socket_name());
/* read $HOME/.ssh/environment. */
if (!options.use_login) {
snprintf(buf, sizeof buf, "%.200s/.ssh/environment",
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]);
}
/* we have to stash the hostname before we close our socket. */
if (options.use_login)
hostname = get_remote_name_or_ip(utmp_len,
options.reverse_mapping_check);
/*
* 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);
/* 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
}
/*
* Must take new environment into use so that .ssh/rc, /etc/sshrc and
* xauth are run in the proper environment.
*/
environ = env;
/*
* Run $HOME/.ssh/rc, /etc/sshrc, or xauth (whichever is found first
* in this order).
*/
if (!options.use_login) {
/* ignore _PATH_SSH_USER_RC for subsystems */
if (!s->is_subsystem && (stat(_PATH_SSH_USER_RC, &st) >= 0)) {
if (debug_flag)
fprintf(stderr, "Running %s %s\n", _PATH_BSHELL,
_PATH_SSH_USER_RC);
f = popen(_PATH_BSHELL " " _PATH_SSH_USER_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_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. */
char *screen = strchr(s->display, ':');
if (debug_flag) {
fprintf(stderr,
"Running %.100s add "
"%.100s %.100s %.100s\n",
options.xauth_location, s->display,
s->auth_proto, s->auth_data);
if (screen != NULL)
fprintf(stderr,
"Adding %.*s/unix%s %s %s\n",
(int)(screen - s->display),
s->display, screen,
s->auth_proto, s->auth_data);
}
snprintf(cmd, sizeof cmd, "%s -q -",
options.xauth_location);
f = popen(cmd, "w");
if (f) {
fprintf(f, "add %s %s %s\n", s->display,
s->auth_proto, s->auth_data);
if (screen != NULL)
fprintf(f, "add %.*s/unix%s %s %s\n",
(int)(screen - s->display),
s->display, screen,
s->auth_proto,
s->auth_data);
pclose(f);
} else {
fprintf(stderr, "Could not run %s\n",
cmd);
}
}
/* Get the last component of the shell name. */
cp = strrchr(shell, '/');
if (cp)
cp++;
else
cp = shell;
}
/* restore SIGPIPE for child */
signal(SIGPIPE, SIG_DFL);
/*
* 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) {
if (!options.use_login) {
char buf[256];
/*
* Check for mail if we have a tty and it was enabled
* in server options.
*/
if (s->ttyfd != -1 && options.check_mail) {
char *mailbox;
struct stat mailstat;
mailbox = getenv("MAIL");
if (mailbox != NULL) {
if (stat(mailbox, &mailstat) != 0 ||
mailstat.st_size == 0)
printf("No mail.\n");
else if (mailstat.st_mtime < mailstat.st_atime)
printf("You have mail.\n");
else
printf("You have new mail.\n");
}
}
/* Start the shell. Set initial character to '-'. */
buf[0] = '-';
strncpy(buf + 1, cp, sizeof(buf) - 1);
buf[sizeof(buf) - 1] = 0;
/* Execute the shell. */
argv[0] = buf;
argv[1] = NULL;
execve(shell, argv, env);
/* Executing the shell failed. */
perror(shell);
exit(1);
} else {
/* Launch login(1). */
execl("/usr/bin/login", "login", "-h", hostname,
"-p", "-f", "--", pw->pw_name, NULL);
/* Login couldn't be executed, die. */
perror("login");
exit(1);
}
}
/*
* Execute the command using the user's shell. This uses the -c
* option to execute the command.
*/
argv[0] = (char *) cp;
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;
sessions[i].self = i;
}
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;
debug("session_new: session %d", i);
return s;
}
}
return NULL;
}
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 %d",
s->used,
s->self,
s,
s->chanid,
s->pid);
}
}
int
session_open(int chanid)
{
Session *s = session_new();
debug("session_open: channel %d", chanid);
if (s == NULL) {
error("no more sessions");
return 0;
}
s->pw = auth_get_user();
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_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;
}
Session *
session_by_pid(pid_t pid)
{
int i;
debug("session_by_pid: pid %d", 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 %d", pid);
session_dump();
return NULL;
}
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_done();
pty_change_window_size(s->ptyfd, s->row, s->col, s->xpixel, s->ypixel);
return 1;
}
int
session_pty_req(Session *s)
{
u_int len;
int n_bytes;
if (no_pty_flag)
return 0;
if (s->ttyfd != -1)
return 0;
s->term = packet_get_string(&len);
s->col = packet_get_int();
s->row = 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. */
if (!pty_allocate(&s->ptyfd, &s->ttyfd, s->tty, sizeof(s->tty))) {
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);
/*
* 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(pty_cleanup_proc, (void *)s);
pty_setowner(s->pw, s->tty);
/* Get window size from the packet. */
pty_change_window_size(s->ptyfd, s->row, s->col, s->xpixel, s->ypixel);
/* Get tty modes from the packet. */
tty_parse_modes(s->ttyfd, &n_bytes);
packet_done();
session_proctitle(s);
return 1;
}
int
session_subsystem_req(Session *s)
{
u_int len;
int success = 0;
char *subsys = packet_get_string(&len);
int i;
packet_done();
log("subsystem request for %s", subsys);
for (i = 0; i < options.num_subsystems; i++) {
if(strcmp(subsys, options.subsystem_name[i]) == 0) {
debug("subsystem: exec() %s", options.subsystem_command[i]);
s->is_subsystem = 1;
do_exec_no_pty(s, options.subsystem_command[i]);
success = 1;
}
}
if (!success)
log("subsystem request for %s failed, subsystem not found", subsys);
xfree(subsys);
return success;
}
int
session_x11_req(Session *s)
{
int fd;
if (no_x11_forwarding_flag) {
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 (xauthfile != NULL) {
debug("X11 fwd already started.");
return 0;
}
debug("Received request for X11 forwarding with auth spoofing.");
if (s->display != NULL)
packet_disconnect("Protocol error: X11 display already set.");
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_done();
s->display = x11_create_display_inet(s->screen, options.x11_display_offset);
if (s->display == NULL) {
xfree(s->auth_proto);
xfree(s->auth_data);
return 0;
}
xauthfile = xmalloc(MAXPATHLEN);
strlcpy(xauthfile, "/tmp/ssh-XXXXXXXX", MAXPATHLEN);
temporarily_use_uid(s->pw);
if (mkdtemp(xauthfile) == NULL) {
restore_uid();
error("private X11 dir: mkdtemp %s failed: %s",
xauthfile, strerror(errno));
xfree(xauthfile);
xauthfile = NULL;
xfree(s->auth_proto);
xfree(s->auth_data);
/* XXXX remove listening channels */
return 0;
}
strlcat(xauthfile, "/cookies", MAXPATHLEN);
fd = open(xauthfile, O_RDWR|O_CREAT|O_EXCL, 0600);
if (fd >= 0)
close(fd);
restore_uid();
fatal_add_cleanup(xauthfile_cleanup_proc, s);
return 1;
}
int
session_shell_req(Session *s)
{
/* if forced_command == NULL, the shell is execed */
char *shell = forced_command;
packet_done();
if (s->ttyfd == -1)
do_exec_no_pty(s, shell);
else
do_exec_pty(s, shell);
return 1;
}
int
session_exec_req(Session *s)
{
u_int len;
char *command = packet_get_string(&len);
packet_done();
if (forced_command) {
original_command = command;
command = forced_command;
debug("Forced command '%.500s'", forced_command);
}
if (s->ttyfd == -1)
do_exec_no_pty(s, command);
else
do_exec_pty(s, command);
if (forced_command == NULL)
xfree(command);
return 1;
}
int
session_auth_agent_req(Session *s)
{
static int called = 0;
packet_done();
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);
}
}
void
session_input_channel_req(int id, void *arg)
{
u_int len;
int reply;
int success = 0;
char *rtype;
Session *s;
Channel *c;
rtype = packet_get_string(&len);
reply = packet_get_char();
s = session_by_channel(id);
if (s == NULL)
fatal("session_input_channel_req: channel %d: no session", id);
c = channel_lookup(id);
if (c == NULL)
fatal("session_input_channel_req: channel %d: bad channel", id);
debug("session_input_channel_req: session %d channel %d request %s reply %d",
s->self, id, rtype, reply);
/*
* 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);
}
}
if (strcmp(rtype, "window-change") == 0) {
success = session_window_change_req(s);
}
if (reply) {
packet_start(success ?
SSH2_MSG_CHANNEL_SUCCESS : SSH2_MSG_CHANNEL_FAILURE);
packet_put_int(c->remote_id);
packet_send();
}
xfree(rtype);
}
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);
}
void
session_pty_cleanup(Session *s)
{
if (s == NULL || s->ttyfd == -1)
return;
debug("session_pty_cleanup: session %d release %s", s->self, s->tty);
/* Cancel the cleanup function. */
fatal_remove_cleanup(pty_cleanup_proc, (void *)s);
/* Record that the user has logged out. */
record_logout(s->pid, s->tty);
/* Release the pseudo-tty. */
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): %s", strerror(errno));
}
void
session_exit_message(Session *s, int status)
{
Channel *c;
if (s == NULL)
fatal("session_close: no session");
c = channel_lookup(s->chanid);
if (c == NULL)
fatal("session_close: session %d: no channel %d",
s->self, s->chanid);
debug("session_exit_message: session %d channel %d pid %d",
s->self, s->chanid, 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_int(WTERMSIG(status));
packet_put_char(WCOREDUMP(status));
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_free(Session *s)
{
debug("session_free: session %d pid %d", s->self, s->pid);
if (s->term)
xfree(s->term);
if (s->display)
xfree(s->display);
if (s->auth_data)
xfree(s->auth_data);
if (s->auth_proto)
xfree(s->auth_proto);
s->used = 0;
}
void
session_close(Session *s)
{
session_pty_cleanup(s);
session_free(s);
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 %d", s->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 channel %d", id);
return;
}
/* disconnect channel */
channel_cancel_cleanup(s->chanid);
s->chanid = -1;
debug("session_close_by_channel: channel %d kill %d", id, s->pid);
if (s->pid == 0) {
/* close session immediately */
session_close(s);
} else {
/* notify child, delay session cleanup */
if (kill(s->pid, (s->ttyfd == -1) ? SIGTERM : SIGHUP) < 0)
error("session_close_by_channel: kill %d: %s",
s->pid, strerror(errno));
}
}
char *
session_tty_list(void)
{
static char buf[1024];
int i;
buf[0] = '\0';
for(i = 0; i < MAX_SESSIONS; i++) {
Session *s = &sessions[i];
if (s->used && s->ttyfd != -1) {
if (buf[0] != '\0')
strlcat(buf, ",", sizeof buf);
strlcat(buf, strrchr(s->tty, '/') + 1, 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());
}
void
do_authenticated2(Authctxt *authctxt)
{
server_loop2();
if (xauthfile)
xauthfile_cleanup_proc(NULL);
}
![[BACK]](/icons/back.gif){kind=icon}
Return to session.c CVS log ![[TXT]](/icons/text.gif){kind=icon}
![[DIR]](/icons/dir.gif){kind=icon}
Up to [local] / src / usr.bin / ssh