289 lines
8.3 KiB
C
289 lines
8.3 KiB
C
/*
|
|
* Copyright © 2014 Red Hat, Inc.
|
|
*
|
|
* Permission is hereby granted, free of charge, to any person obtaining a
|
|
* copy of this software and associated documentation files (the "Software"),
|
|
* to deal in the Software without restriction, including without limitation
|
|
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
|
|
* and/or sell copies of the Software, and to permit persons to whom the
|
|
* Software is furnished to do so, subject to the following conditions:
|
|
*
|
|
* The above copyright notice and this permission notice (including the next
|
|
* paragraph) shall be included in all copies or substantial portions of the
|
|
* Software.
|
|
*
|
|
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
|
|
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
|
|
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
|
|
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
|
|
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
|
|
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
|
|
* DEALINGS IN THE SOFTWARE.
|
|
*
|
|
* Author: Hans de Goede <hdegoede@redhat.com>
|
|
*/
|
|
|
|
#include "dix-config.h"
|
|
#include "xorg-config.h"
|
|
|
|
#include <errno.h>
|
|
#include <fcntl.h>
|
|
#include <limits.h>
|
|
#include <stdint.h>
|
|
#include <stdio.h>
|
|
#include <stdlib.h>
|
|
#include <string.h>
|
|
#include <sys/ioctl.h>
|
|
#include <sys/stat.h>
|
|
#ifdef HAVE_SYS_SYSMACROS_H
|
|
#include <sys/sysmacros.h>
|
|
#endif
|
|
#include <sys/types.h>
|
|
#if defined(__FreeBSD__) || defined(__FreeBSD_kernel__)
|
|
#include <sys/consio.h>
|
|
#endif
|
|
#include <unistd.h>
|
|
#ifdef WITH_LIBDRM
|
|
#include <drm.h>
|
|
#include <xf86drm.h> /* For DRM_DEV_NAME */
|
|
#endif
|
|
|
|
#include "misc.h"
|
|
|
|
#define CONFIG_FILE SYSCONFDIR "/X11/Xwrapper.config"
|
|
|
|
static const char *progname;
|
|
|
|
enum { ROOT_ONLY, CONSOLE_ONLY, ANYBODY };
|
|
|
|
/* KISS non locale / LANG parsing isspace version */
|
|
static int is_space(char c)
|
|
{
|
|
return c == ' ' || c == '\t' || c == '\n';
|
|
}
|
|
|
|
static char *strip(char *s)
|
|
{
|
|
int i;
|
|
|
|
/* Strip leading whitespace */
|
|
while (s[0] && is_space(s[0]))
|
|
s++;
|
|
|
|
/* Strip trailing whitespace */
|
|
i = strlen(s) - 1;
|
|
while (i >= 0 && is_space(s[i])) {
|
|
s[i] = 0;
|
|
i--;
|
|
}
|
|
|
|
return s;
|
|
}
|
|
|
|
static void parse_config(int *allowed, int *needs_root_rights)
|
|
{
|
|
FILE *f;
|
|
char buf[1024];
|
|
char *stripped, *equals, *key, *value;
|
|
int line = 0;
|
|
|
|
f = fopen(CONFIG_FILE, "r");
|
|
if (!f)
|
|
return;
|
|
|
|
while (fgets(buf, sizeof(buf), f)) {
|
|
line++;
|
|
|
|
/* Skip comments and empty lines */
|
|
stripped = strip(buf);
|
|
if (stripped[0] == '#' || stripped[0] == 0)
|
|
continue;
|
|
|
|
/* Split in a key + value pair */
|
|
equals = strchr(stripped, '=');
|
|
if (!equals) {
|
|
fprintf(stderr, "%s: Syntax error at %s line %d\n", progname,
|
|
CONFIG_FILE, line);
|
|
exit(1);
|
|
}
|
|
*equals = 0;
|
|
key = strip(stripped); /* To remove trailing whitespace from key */
|
|
value = strip(equals + 1); /* To remove leading whitespace from val */
|
|
if (!key[0]) {
|
|
fprintf(stderr, "%s: Missing key at %s line %d\n", progname,
|
|
CONFIG_FILE, line);
|
|
exit(1);
|
|
}
|
|
if (!value[0]) {
|
|
fprintf(stderr, "%s: Missing value at %s line %d\n", progname,
|
|
CONFIG_FILE, line);
|
|
exit(1);
|
|
}
|
|
|
|
/* And finally process */
|
|
if (strcmp(key, "allowed_users") == 0) {
|
|
if (strcmp(value, "rootonly") == 0)
|
|
*allowed = ROOT_ONLY;
|
|
else if (strcmp(value, "console") == 0)
|
|
*allowed = CONSOLE_ONLY;
|
|
else if (strcmp(value, "anybody") == 0)
|
|
*allowed = ANYBODY;
|
|
else {
|
|
fprintf(stderr,
|
|
"%s: Invalid value '%s' for 'allowed_users' at %s line %d\n",
|
|
progname, value, CONFIG_FILE, line);
|
|
exit(1);
|
|
}
|
|
}
|
|
else if (strcmp(key, "needs_root_rights") == 0) {
|
|
if (strcmp(value, "yes") == 0)
|
|
*needs_root_rights = 1;
|
|
else if (strcmp(value, "no") == 0)
|
|
*needs_root_rights = 0;
|
|
else if (strcmp(value, "auto") == 0)
|
|
*needs_root_rights = -1;
|
|
else {
|
|
fprintf(stderr,
|
|
"%s: Invalid value '%s' for 'needs_root_rights' at %s line %d\n",
|
|
progname, value, CONFIG_FILE, line);
|
|
exit(1);
|
|
}
|
|
}
|
|
else if (strcmp(key, "nice_value") == 0) {
|
|
/* Backward compatibility with older Debian Xwrapper, ignore */
|
|
}
|
|
else {
|
|
fprintf(stderr, "%s: Invalid key '%s' at %s line %d\n", key,
|
|
progname, CONFIG_FILE, line);
|
|
exit(1);
|
|
}
|
|
}
|
|
fclose(f);
|
|
}
|
|
|
|
static int on_console(int fd)
|
|
{
|
|
#if defined(__linux__)
|
|
struct stat st;
|
|
int r;
|
|
|
|
r = fstat(fd, &st);
|
|
if (r == 0 && S_ISCHR(st.st_mode) && major(st.st_rdev) == 4)
|
|
return 1;
|
|
#elif defined(__FreeBSD__) || defined(__FreeBSD_kernel__)
|
|
int idx;
|
|
|
|
if (ioctl(fd, VT_GETINDEX, &idx) != -1)
|
|
return 1;
|
|
#else
|
|
#warning This program needs porting to your kernel.
|
|
static int seen;
|
|
|
|
if (!seen) {
|
|
fprintf(stderr, "%s: Unable to determine if running on a console\n",
|
|
progname);
|
|
seen = 1;
|
|
}
|
|
#endif
|
|
|
|
return 0;
|
|
}
|
|
|
|
int main(int argc, char *argv[])
|
|
{
|
|
#ifdef WITH_LIBDRM
|
|
struct drm_mode_card_res res;
|
|
#endif
|
|
char buf[PATH_MAX];
|
|
int i, r, fd;
|
|
int kms_cards = 0;
|
|
int total_cards = 0;
|
|
int allowed = CONSOLE_ONLY;
|
|
int needs_root_rights = -1;
|
|
char *const empty_envp[1] = { NULL, };
|
|
|
|
progname = argv[0];
|
|
|
|
parse_config(&allowed, &needs_root_rights);
|
|
|
|
/* For non root users check if they are allowed to run the X server */
|
|
if (getuid() != 0) {
|
|
switch (allowed) {
|
|
case ROOT_ONLY:
|
|
/* Already checked above */
|
|
fprintf(stderr, "%s: Only root is allowed to run the X server\n", argv[0]);
|
|
exit(1);
|
|
break;
|
|
case CONSOLE_ONLY:
|
|
/* Some of stdin / stdout / stderr maybe redirected to a file */
|
|
for (i = STDIN_FILENO; i <= STDERR_FILENO; i++) {
|
|
if (on_console(i))
|
|
break;
|
|
}
|
|
if (i > STDERR_FILENO) {
|
|
fprintf(stderr, "%s: Only console users are allowed to run the X server\n", argv[0]);
|
|
exit(1);
|
|
}
|
|
break;
|
|
case ANYBODY:
|
|
break;
|
|
}
|
|
}
|
|
|
|
#ifdef WITH_LIBDRM
|
|
/* Detect if we need root rights, except when overridden by the config */
|
|
if (needs_root_rights == -1) {
|
|
for (i = 0; i < 16; i++) {
|
|
snprintf(buf, sizeof(buf), DRM_DEV_NAME, DRM_DIR_NAME, i);
|
|
fd = open(buf, O_RDWR);
|
|
if (fd == -1)
|
|
continue;
|
|
|
|
total_cards++;
|
|
|
|
memset(&res, 0, sizeof(struct drm_mode_card_res));
|
|
r = ioctl(fd, DRM_IOCTL_MODE_GETRESOURCES, &res);
|
|
if (r == 0)
|
|
kms_cards++;
|
|
|
|
close(fd);
|
|
}
|
|
}
|
|
#endif
|
|
|
|
/* If we've found cards, and all cards support kms, drop root rights */
|
|
if (needs_root_rights == 0 || (total_cards && kms_cards == total_cards)) {
|
|
gid_t realgid = getgid();
|
|
uid_t realuid = getuid();
|
|
|
|
if (setresgid(-1, realgid, realgid) != 0) {
|
|
fprintf(stderr, "%s: Could not drop setgid privileges: %s\n",
|
|
progname, strerror(errno));
|
|
exit(1);
|
|
}
|
|
if (setresuid(-1, realuid, realuid) != 0) {
|
|
fprintf(stderr, "%s: Could not drop setuid privileges: %s\n",
|
|
progname, strerror(errno));
|
|
exit(1);
|
|
}
|
|
}
|
|
|
|
snprintf(buf, sizeof(buf), "%s/Xorg", SUID_WRAPPER_DIR);
|
|
|
|
/* Check if the server is executable by our real uid */
|
|
if (access(buf, X_OK) != 0) {
|
|
fprintf(stderr, "%s: Missing execute permissions for %s: %s\n",
|
|
progname, buf, strerror(errno));
|
|
exit(1);
|
|
}
|
|
|
|
argv[0] = buf;
|
|
if (getuid() == geteuid())
|
|
(void) execv(argv[0], argv);
|
|
else
|
|
(void) execve(argv[0], argv, empty_envp);
|
|
fprintf(stderr, "%s: Failed to execute %s: %s\n",
|
|
progname, buf, strerror(errno));
|
|
exit(1);
|
|
}
|