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/* guestfish - the filesystem interactive shell
* Copyright (C) 2009 Red Hat Inc.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#include <config.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <libintl.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/un.h>
#include <signal.h>
#include <sys/socket.h>
#include <errno.h>
#include <rpc/types.h>
#include <rpc/xdr.h>
#include "fish.h"
#include "rc_protocol.h"
/* Because this is a Unix domain socket, the total path length must be
* under 108 bytes.
*/
#define SOCKET_DIR "/tmp/.guestfish-%d" /* euid */
#define SOCKET_PATH "/tmp/.guestfish-%d/socket-%d" /* euid, pid */
static void
create_sockdir (void)
{
uid_t euid = geteuid ();
char dir[128];
int r;
struct stat statbuf;
/* Create the directory, and ensure it is owned by the user. */
snprintf (dir, sizeof dir, SOCKET_DIR, euid);
r = mkdir (dir, 0700);
if (r == -1 && errno != EEXIST) {
error:
perror (dir);
exit (EXIT_FAILURE);
}
if (lstat (dir, &statbuf) == -1)
goto error;
if (!S_ISDIR (statbuf.st_mode) ||
(statbuf.st_mode & 0777) != 0700 ||
statbuf.st_uid != euid) {
fprintf (stderr,
_("guestfish: '%s' is not a directory or has insecure owner or permissions\n"),
dir);
exit (EXIT_FAILURE);
}
}
static void
create_sockpath (pid_t pid, char *sockpath, size_t len,
struct sockaddr_un *addr)
{
uid_t euid = geteuid ();
create_sockdir ();
snprintf (sockpath, len, SOCKET_PATH, euid, pid);
addr->sun_family = AF_UNIX;
strcpy (addr->sun_path, sockpath);
}
static const socklen_t controllen = CMSG_LEN (sizeof (int));
static void
receive_stdout (int s)
{
static struct cmsghdr *cmptr = NULL, *h;
struct msghdr msg;
struct iovec iov[1];
/* Our 1 byte buffer */
char buf[1];
if (NULL == cmptr) {
cmptr = malloc (controllen);
if (NULL == cmptr) {
perror ("malloc");
exit (EXIT_FAILURE);
}
}
/* Don't specify a source */
memset (&msg, 0, sizeof msg);
msg.msg_name = NULL;
msg.msg_namelen = 0;
/* Initialise the msghdr to receive zero byte */
iov[0].iov_base = buf;
iov[0].iov_len = 1;
msg.msg_iov = iov;
msg.msg_iovlen = 1;
/* Initialise the control data */
msg.msg_control = cmptr;
msg.msg_controllen = controllen;
/* Read a message from the socket */
ssize_t n = recvmsg (s, &msg, 0);
if (n < 0) {
perror ("recvmsg stdout fd");
exit (EXIT_FAILURE);
}
h = CMSG_FIRSTHDR(&msg);
if (NULL == h) {
fprintf (stderr, "didn't receive a stdout file descriptor\n");
}
else {
/* Extract the transferred file descriptor from the control data */
unsigned char *data = CMSG_DATA (h);
int fd = *(int *)data;
/* Duplicate the received file descriptor to stdout */
dup2 (fd, STDOUT_FILENO);
close (fd);
}
}
static void
send_stdout (int s)
{
static struct cmsghdr *cmptr = NULL;
struct msghdr msg;
struct iovec iov[1];
/* Our 1 byte dummy buffer */
char buf[1];
/* Don't specify a destination */
memset (&msg, 0, sizeof msg);
msg.msg_name = NULL;
msg.msg_namelen = 0;
/* Initialise the msghdr to send zero byte */
iov[0].iov_base = buf;
iov[0].iov_len = 1;
msg.msg_iov = iov;
msg.msg_iovlen = 1;
/* Initialize the zero byte */
buf[0] = 0;
/* Initialize the control data */
if (NULL == cmptr) {
cmptr = malloc (controllen);
if (NULL == cmptr) {
perror ("malloc");
exit (EXIT_FAILURE);
}
}
cmptr->cmsg_level = SOL_SOCKET;
cmptr->cmsg_type = SCM_RIGHTS;
cmptr->cmsg_len = controllen;
/* Add control header to the message */
msg.msg_control = cmptr;
msg.msg_controllen = controllen;
/* Add STDOUT to the control data */
unsigned char *data = CMSG_DATA (cmptr);
*(int *)data = STDOUT_FILENO;
if (sendmsg (s, &msg, 0) != 1) {
perror ("sendmsg stdout fd");
exit (EXIT_FAILURE);
}
}
static void
close_stdout (void)
{
int fd;
fd = open ("/dev/null", O_WRONLY);
if (fd == -1)
perror ("/dev/null");
else {
dup2 (fd, STDOUT_FILENO);
close (fd);
}
}
/* Remote control server. */
void
rc_listen (void)
{
char sockpath[128];
pid_t pid;
struct sockaddr_un addr;
int sock, s;
size_t i;
FILE *fp;
XDR xdr, xdr2;
guestfish_hello hello;
guestfish_call call;
guestfish_reply reply;
char **argv;
size_t argc;
memset (&hello, 0, sizeof hello);
memset (&call, 0, sizeof call);
create_sockdir ();
pid = fork ();
if (pid == -1) {
perror ("fork");
exit (EXIT_FAILURE);
}
if (pid > 0) {
/* Parent process. */
if (!remote_control_csh)
printf ("GUESTFISH_PID=%d; export GUESTFISH_PID\n", pid);
else
printf ("setenv GUESTFISH_PID %d\n", pid);
fflush (stdout);
_exit (0);
}
/* Child process.
*
* Create the listening socket for accepting commands.
*
* Unfortunately there is a small but unavoidable race here. We
* don't know the PID until after we've forked, so we cannot be
* sure the socket is created from the point of view of the parent
* (if the child is very slow).
*/
pid = getpid ();
create_sockpath (pid, sockpath, sizeof sockpath, &addr);
sock = socket (AF_UNIX, SOCK_STREAM|SOCK_CLOEXEC, 0);
if (sock == -1) {
perror ("socket");
exit (EXIT_FAILURE);
}
unlink (sockpath);
if (bind (sock, (struct sockaddr *) &addr, sizeof addr) == -1) {
perror (sockpath);
exit (EXIT_FAILURE);
}
if (listen (sock, 4) == -1) {
perror ("listen");
exit (EXIT_FAILURE);
}
/* Read commands and execute them. */
while (!quit) {
/* Before waiting, close stdout and substitute /dev/null. This is
* necessary so that eval `guestfish --listen` doesn't block
* forever.
*/
close_stdout ();
s = accept4 (sock, NULL, NULL, SOCK_CLOEXEC);
if (s == -1)
perror ("accept");
else {
receive_stdout(s);
fp = fdopen (s, "r+");
xdrstdio_create (&xdr, fp, XDR_DECODE);
if (!xdr_guestfish_hello (&xdr, &hello)) {
fprintf (stderr, _("guestfish: protocol error: could not read 'hello' message\n"));
goto error;
}
if (STRNEQ (hello.vers, PACKAGE_VERSION)) {
fprintf (stderr, _("guestfish: protocol error: version mismatch, server version '%s' does not match client version '%s'. The two versions must match exactly.\n"),
PACKAGE_VERSION,
hello.vers);
xdr_free ((xdrproc_t) xdr_guestfish_hello, (char *) &hello);
goto error;
}
xdr_free ((xdrproc_t) xdr_guestfish_hello, (char *) &hello);
while (xdr_guestfish_call (&xdr, &call)) {
/* We have to extend and NULL-terminate the argv array. */
argc = call.args.args_len;
argv = realloc (call.args.args_val, (argc+1) * sizeof (char *));
if (argv == NULL) {
perror ("realloc");
exit (EXIT_FAILURE);
}
call.args.args_val = argv;
argv[argc] = NULL;
if (verbose) {
fprintf (stderr, "guestfish(%d): %s", pid, call.cmd);
for (i = 0; i < argc; ++i)
fprintf (stderr, " %s", argv[i]);
fprintf (stderr, "\n");
}
/* Run the command. */
reply.r = issue_command (call.cmd, argv, NULL, 0);
xdr_free ((xdrproc_t) xdr_guestfish_call, (char *) &call);
/* RHBZ#802389: If the command is quit, close the handle right
* away. Note that the main while loop will exit preventing
* 'g' from being reused.
*/
if (quit) {
guestfs_close (g);
g = NULL;
}
/* Send the reply. */
xdrstdio_create (&xdr2, fp, XDR_ENCODE);
(void) xdr_guestfish_reply (&xdr2, &reply);
xdr_destroy (&xdr2);
/* Exit on error? */
if (call.exit_on_error && reply.r == -1) {
unlink (sockpath);
exit (EXIT_FAILURE);
}
}
error:
xdr_destroy (&xdr); /* NB. This doesn't close 'fp'. */
fclose (fp); /* Closes the underlying socket 's'. */
}
}
unlink (sockpath);
/* This returns to 'fish.c', where it jumps to global cleanups and exits. */
}
/* Remote control client. */
int
rc_remote (int pid, const char *cmd, size_t argc, char *argv[],
int exit_on_error)
{
guestfish_hello hello;
guestfish_call call;
guestfish_reply reply;
char sockpath[128];
struct sockaddr_un addr;
int sock;
FILE *fp;
XDR xdr;
memset (&reply, 0, sizeof reply);
/* This is fine as long as we never try to xdr_free this struct. */
hello.vers = (char *) PACKAGE_VERSION;
/* Check the other end is still running. */
if (kill (pid, 0) == -1) {
fprintf (stderr, _("guestfish: remote: looks like the server is not running\n"));
return -1;
}
create_sockpath (pid, sockpath, sizeof sockpath, &addr);
sock = socket (AF_UNIX, SOCK_STREAM|SOCK_CLOEXEC, 0);
if (sock == -1) {
perror ("socket");
return -1;
}
if (connect (sock, (struct sockaddr *) &addr, sizeof addr) == -1) {
perror (sockpath);
fprintf (stderr, _("guestfish: remote: looks like the server is not running\n"));
close (sock);
return -1;
}
send_stdout(sock);
/* Send the greeting. */
fp = fdopen (sock, "r+");
xdrstdio_create (&xdr, fp, XDR_ENCODE);
if (!xdr_guestfish_hello (&xdr, &hello)) {
fprintf (stderr, _("guestfish: protocol error: could not send initial greeting to server\n"));
xdr_destroy (&xdr);
fclose (fp);
return -1;
}
/* Send the command. The server supports reading multiple commands
* per connection, but this code only ever sends one command.
*/
call.cmd = (char *) cmd;
call.args.args_len = argc;
call.args.args_val = argv;
call.exit_on_error = exit_on_error;
if (!xdr_guestfish_call (&xdr, &call)) {
fprintf (stderr, _("guestfish: protocol error: could not send initial greeting to server\n"));
xdr_destroy (&xdr);
fclose (fp);
return -1;
}
xdr_destroy (&xdr);
/* Wait for the reply. */
xdrstdio_create (&xdr, fp, XDR_DECODE);
if (!xdr_guestfish_reply (&xdr, &reply)) {
fprintf (stderr, _("guestfish: protocol error: could not decode reply from server\n"));
xdr_destroy (&xdr);
fclose (fp);
return -1;
}
xdr_destroy (&xdr);
fclose (fp);
return reply.r;
}
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