tyler.durden
/
openssh-portable
mirror of https://github.com/PowerShell/openssh-portable.git
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity
openssh-portable/session.c

1614 lines
41 KiB
C
Raw Blame History

/*
* Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
* All rights reserved
*/
/*
* SSH2 support by Markus Friedl.
* Copyright (c) 2000 Markus Friedl. All rights reserved.
*/
#include "includes.h"
RCSID("$OpenBSD: session.c,v 1.12 2000/05/03 18:03:07 markus Exp $");
#include "xmalloc.h"
#include "ssh.h"
#include "pty.h"
#include "packet.h"
#include "buffer.h"
#include "cipher.h"
#include "mpaux.h"
#include "servconf.h"
#include "uidswap.h"
#include "compat.h"
#include "channels.h"
#include "nchan.h"
#include "bufaux.h"
#include "ssh2.h"
#include "auth.h"
/* types */
#define TTYSZ 64
typedef struct Session Session;
struct Session {
int used;
int self;
int extended;
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;
};
/* 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, struct passwd * pw);
void do_exec_no_pty(Session *s, const char *command, struct passwd * pw);
void
do_child(const char *command, struct passwd * pw, const char *term,
const char *display, const char *auth_proto,
const char *auth_data, const char *ttyname);
/* import */
extern ServerOptions options;
#ifdef HAVE___PROGNAME
extern char *__progname;
#else /* HAVE___PROGNAME */
static const char *__progname = "sshd";
#endif /* HAVE___PROGNAME */
extern int log_stderr;
extern int debug_flag;
/* Local Xauthority file. */
static char *xauthfile;
/* data */
#define MAX_SESSIONS 10
Session sessions[MAX_SESSIONS];
#ifdef WITH_AIXAUTHENTICATE
/* AIX's lastlogin message, set in auth1.c */
char *aixloginmsg;
#endif /* WITH_AIXAUTHENTICATE */
/* Flags set in auth-rsa from authorized_keys flags. These are set in auth-rsa.c. */
int no_port_forwarding_flag = 0;
int no_agent_forwarding_flag = 0;
int no_x11_forwarding_flag = 0;
int no_pty_flag = 0;
/* RSA authentication "command=" option. */
char *forced_command = NULL;
/* RSA authentication "environment=" options. */
struct envstring *custom_environment = NULL;
/*
* 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_authenticated(struct passwd * pw)
{
Session *s;
int type;
int compression_level = 0, enable_compression_after_reply = 0;
int have_pty = 0;
char *command;
int n_bytes;
int plen;
unsigned int proto_len, data_len, dlen;
/*
* Cancel the alarm we set to limit the time taken for
* authentication.
*/
alarm(0);
/*
* Inform the channel mechanism that we are the server side and that
* the client may request to connect to any port at all. (The user
* could do it anyway, and we wouldn\'t know what is permitted except
* by the client telling us, so we can equally well trust the client
* not to request anything bogus.)
*/
if (!no_port_forwarding_flag)
channel_permit_all_opens();
s = session_new();
s->pw = pw;
/*
* We stay in this loop until the client requests to execute a shell
* or a command.
*/
for (;;) {
int 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(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;
}
#ifdef XAUTH_PATH
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);
packet_integrity_check(plen, 4 + proto_len + 4 + data_len + 4, type);
if (packet_get_protocol_flags() & SSH_PROTOFLAG_SCREEN_NUMBER)
s->screen = packet_get_int();
else
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(pw->pw_uid);
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);
open(xauthfile, O_RDWR|O_CREAT|O_EXCL, 0600);
restore_uid();
fatal_add_cleanup(xauthfile_cleanup_proc, NULL);
success = 1;
break;
#else /* XAUTH_PATH */
packet_send_debug("No xauth program; cannot forward with spoofing.");
break;
#endif /* XAUTH_PATH */
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.");
auth_input_request_forwarding(pw);
success = 1;
break;
case SSH_CMSG_PORT_FORWARD_REQUEST:
if (no_port_forwarding_flag) {
debug("Port forwarding not permitted for this authentication.");
break;
}
debug("Received TCP/IP port forwarding request.");
channel_input_port_forward_request(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:
/* Set interactive/non-interactive mode. */
packet_set_interactive(have_pty || s->display != NULL,
options.keepalives);
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) {
command = forced_command;
debug("Forced command '%.500s'", forced_command);
}
if (have_pty)
do_exec_pty(s, command, pw);
else
do_exec_no_pty(s, command, pw);
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, struct passwd * pw)
{
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);
#ifdef USE_PAM
do_pam_setcred();
#endif /* USE_PAM */
/* 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(command, pw, NULL, s->display, s->auth_proto, s->auth_data, NULL);
/* NOTREACHED */
}
if (pid < 0)
packet_disconnect("fork failed: %.100s", strerror(errno));
s->pid = pid;
#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->extended ? perr[0] : -1);
} else {
/* Enter the interactive session. */
server_loop(pid, pin[1], pout[0], perr[0]);
/* server_loop has closed pin[1], pout[1], and perr[1]. */
}
#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->extended ? err[1] : -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, struct passwd * pw)
{
FILE *f;
char buf[100], *time_string;
char line[256];
const char *hostname;
int fdout, ptyfd, ttyfd, ptymaster;
int quiet_login;
pid_t pid;
socklen_t fromlen;
struct sockaddr_storage from;
struct stat st;
time_t last_login_time;
if (s == NULL)
fatal("do_exec_pty: no session");
ptyfd = s->ptyfd;
ttyfd = s->ttyfd;
/* Get remote host name. */
hostname = get_canonical_hostname();
/*
* Get the time when the user last logged in. Buf will be set to
* contain the hostname the last login was from.
*/
if (!options.use_login) {
last_login_time = get_last_login_time(pw->pw_uid, pw->pw_name,
buf, sizeof(buf));
}
#ifdef USE_PAM
do_pam_session(pw->pw_name, s->tty);
do_pam_setcred();
#endif /* USE_PAM */
/* Fork the child. */
if ((pid = fork()) == 0) {
pid = getpid();
/* 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);
/* XXXX ? move to do_child() ??*/
/*
* Get IP address of client. This is needed because we want
* to record where the user logged in from. If the
* connection is not a socket, let the ip 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();
}
}
/* Record that there was a login on that terminal. */
record_login(pid, s->tty, pw->pw_name, pw->pw_uid, hostname,
(struct sockaddr *)&from);
/* Check if .hushlogin exists. */
snprintf(line, sizeof line, "%.200s/.hushlogin", pw->pw_dir);
quiet_login = stat(line, &st) >= 0;
#ifdef USE_PAM
if (!quiet_login)
print_pam_messages();
#endif /* USE_PAM */
/*
* If the user has logged in before, display the time of last
* login. However, don't display anything extra if a command
* has been specified (so that ssh can be used to execute
* commands on a remote machine without users knowing they
* are going to another machine). Login(1) will do this for
* us as well, so check if login(1) is used
*/
if (command == NULL && last_login_time != 0 && !quiet_login &&
!options.use_login) {
/* Convert the date to a string. */
time_string = ctime(&last_login_time);
/* Remove the trailing newline. */
if (strchr(time_string, '\n'))
*strchr(time_string, '\n') = 0;
/* Display the last login time. Host if displayed
if known. */
if (strcmp(buf, "") == 0)
printf("Last login: %s\r\n", time_string);
else
printf("Last login: %s from %s\r\n", time_string, buf);
}
/*
* Print /etc/motd unless a command was specified or printing
* it was disabled in server options or login(1) will be
* used. Note that some machines appear to print it in
* /etc/profile or similar.
*/
if (command == NULL && options.print_motd && !quiet_login &&
!options.use_login) {
/* Print /etc/motd if it exists. */
f = fopen("/etc/motd", "r");
if (f) {
while (fgets(line, sizeof(line), f))
fputs(line, stdout);
fclose(f);
}
}
#if defined(WITH_AIXAUTHENTICATE)
/*
* AIX handles the lastlog info differently. Display it here.
*/
if (command == NULL && aixloginmsg && *aixloginmsg &&
!quiet_login && !options.use_login) {
printf("%s\n", aixloginmsg);
}
#endif
/* Do common processing for the child, such as execing the command. */
do_child(command, pw, s->term, s->display, s->auth_proto, s->auth_data, s->tty);
/* 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. */
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);
}
}
/*
* 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, unsigned int *envsizep, const char *name,
const char *value)
{
unsigned 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, unsigned 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);
}
#ifdef USE_PAM
/*
* Sets any environment variables which have been specified by PAM
*/
void do_pam_environment(char ***env, int *envsize)
{
char *equals, var_name[512], var_val[512];
char **pam_env;
int i;
if ((pam_env = fetch_pam_environment()) == NULL)
return;
for(i = 0; pam_env[i] != NULL; i++) {
if ((equals = strstr(pam_env[i], "=")) == NULL)
continue;
if (strlen(pam_env[i]) < (sizeof(var_name) - 1)) {
memset(var_name, '\0', sizeof(var_name));
memset(var_val, '\0', sizeof(var_val));
strncpy(var_name, pam_env[i], equals - pam_env[i]);
strcpy(var_val, equals + 1);
debug("PAM environment: %s=%s", var_name, var_val);
child_set_env(env, envsize, var_name, var_val);
}
}
}
#endif /* USE_PAM */
/*
* 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(const char *command, struct passwd * pw, const char *term,
const char *display, const char *auth_proto,
const char *auth_data, const char *ttyname)
{
const char *shell, *cp = NULL;
char buf[256];
FILE *f;
unsigned int envsize, i;
char **env;
extern char **environ;
struct stat st;
char *argv[10];
#ifndef USE_PAM /* pam_nologin handles this */
f = fopen("/etc/nologin", "r");
if (f) {
/* /etc/nologin exists. Print its contents and exit. */
while (fgets(buf, sizeof(buf), f))
fputs(buf, stderr);
fclose(f);
if (pw->pw_uid != 0)
exit(254);
}
#endif /* USE_PAM */
/* Set login name in the kernel. */
if (setlogin(pw->pw_name) < 0)
error("setlogin failed: %s", strerror(errno));
/* Set 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) {
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->pw_uid);
}
if (getuid() != pw->pw_uid || geteuid() != pw->pw_uid)
fatal("Failed to set uids to %d.", (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 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);
child_set_env(&env, &envsize, "PATH", _PATH_STDPATH);
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 (ttyname)
child_set_env(&env, &envsize, "SSH_TTY", ttyname);
if (term)
child_set_env(&env, &envsize, "TERM", term);
if (display)
child_set_env(&env, &envsize, "DISPLAY", display);
#ifdef _AIX
{
char *authstate,*krb5cc;
if ((authstate = getenv("AUTHSTATE")) != NULL)
child_set_env(&env,&envsize,"AUTHSTATE",authstate);
if ((krb5cc = getenv("KRB5CCNAME")) != NULL)
child_set_env(&env,&envsize,"KRB5CCNAME",krb5cc);
}
#endif
#ifdef KRB4
{
extern char *ticket;
if (ticket)
child_set_env(&env, &envsize, "KRBTKFILE", ticket);
}
#endif /* KRB4 */
#ifdef USE_PAM
/* Pull in any environment variables that may have been set by PAM. */
do_pam_environment(&env, &envsize);
#endif /* USE_PAM */
read_environment_file(&env,&envsize,"/etc/environment");
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]);
}
/*
* 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));
/*
* 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) {
if (stat(SSH_USER_RC, &st) >= 0) {
if (debug_flag)
fprintf(stderr, "Running /bin/sh %s\n", SSH_USER_RC);
f = popen("/bin/sh " SSH_USER_RC, "w");
if (f) {
if (auth_proto != NULL && auth_data != NULL)
fprintf(f, "%s %s\n", auth_proto, auth_data);
pclose(f);
} else
fprintf(stderr, "Could not run %s\n", SSH_USER_RC);
} else if (stat(SSH_SYSTEM_RC, &st) >= 0) {
if (debug_flag)
fprintf(stderr, "Running /bin/sh %s\n", SSH_SYSTEM_RC);
f = popen("/bin/sh " SSH_SYSTEM_RC, "w");
if (f) {
if (auth_proto != NULL && auth_data != NULL)
fprintf(f, "%s %s\n", auth_proto, auth_data);
pclose(f);
} else
fprintf(stderr, "Could not run %s\n", SSH_SYSTEM_RC);
}
#ifdef XAUTH_PATH
else {
/* Add authority data to .Xauthority if appropriate. */
if (auth_proto != NULL && auth_data != NULL) {
char *screen = strchr(display, ':');
if (debug_flag) {
fprintf(stderr, "Running %.100s add %.100s %.100s %.100s\n",
XAUTH_PATH, display, auth_proto, auth_data);
if (screen != NULL)
fprintf(stderr, "Adding %.*s/unix%s %s %s\n",
screen-display, display, screen, auth_proto, auth_data);
}
f = popen(XAUTH_PATH " -q -", "w");
if (f) {
fprintf(f, "add %s %s %s\n", display, auth_proto, auth_data);
if (screen != NULL)
fprintf(f, "add %.*s/unix%s %s %s\n",
screen-display, display, screen, auth_proto, auth_data);
pclose(f);
} else
fprintf(stderr, "Could not run %s -q -\n", XAUTH_PATH);
}
}
#endif /* XAUTH_PATH */
/* Get the last component of the shell name. */
cp = strrchr(shell, '/');
if (cp)
cp++;
else
cp = 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) {
if (!options.use_login) {
char buf[256];
/*
* Check for mail if we have a tty and it was enabled
* in server options.
*/
if (ttyname && 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", get_remote_ipaddr(),
"-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) {
s->pid = 0;
s->extended = 0;
s->chanid = -1;
s->ptyfd = -1;
s->ttyfd = -1;
s->term = NULL;
s->pw = NULL;
s->display = NULL;
s->screen = 0;
s->auth_data = NULL;
s->auth_proto = NULL;
s->used = 1;
s->pw = NULL;
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 %i", 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)
{
unsigned int len;
char *term_modes; /* encoded terminal modes */
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();
term_modes = packet_get_string(&len);
packet_done();
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);
xfree(term_modes);
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);
session_proctitle(s);
/* XXX parse and set terminal modes */
xfree(term_modes);
return 1;
}
int
session_subsystem_req(Session *s)
{
unsigned int len;
int success = 0;
char *subsys = packet_get_string(&len);
packet_done();
log("subsystem request for %s", subsys);
xfree(subsys);
return success;
}
int
session_x11_req(Session *s)
{
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->pw_uid);
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);
open(xauthfile, O_RDWR|O_CREAT|O_EXCL, 0600);
restore_uid();
fatal_add_cleanup(xauthfile_cleanup_proc, s);
return 1;
}
void
session_input_channel_req(int id, void *arg)
{
unsigned 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
* or programm is executed
*/
if (c->type == SSH_CHANNEL_LARVAL) {
if (strcmp(rtype, "shell") == 0) {
packet_done();
s->extended = 1;
if (s->ttyfd == -1)
do_exec_no_pty(s, NULL, s->pw);
else
do_exec_pty(s, NULL, s->pw);
success = 1;
} else if (strcmp(rtype, "exec") == 0) {
char *command = packet_get_string(&len);
packet_done();
s->extended = 1;
if (s->ttyfd == -1)
do_exec_no_pty(s, command, s->pw);
else
do_exec_pty(s, command, s->pw);
xfree(command);
success = 1;
} 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, "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);
}
void
session_pty_cleanup(Session *s)
{
if (s == NULL || s->ttyfd == -1)
return;
debug("session_pty_cleanup: session %i 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));
#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_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(void)
{
/*
* Cancel the alarm we set to limit the time taken for
* authentication.
*/
alarm(0);
server_loop2();
if (xauthfile)
xauthfile_cleanup_proc(NULL);
}
Reference in New Issue View Git Blame Copy Permalink