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/*
* Copyright (C) 2014, 2015 netblue30 (netblue30@yahoo.com)
*
* This file is part of firejail project
*
* 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 "firejail.h"
#include <sys/mount.h>
#include <linux/limits.h>
#include <glob.h>
#include <dirent.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <unistd.h>
#include <grp.h>
static void skel(const char *homedir, uid_t u, gid_t g) {
char *fname;
// zsh
if (arg_zsh) {
// copy skel files
if (asprintf(&fname, "%s/.zshrc", homedir) == -1)
errExit("asprintf");
struct stat s;
// don't copy it if we already have the file
if (stat(fname, &s) == 0)
return;
if (stat("/etc/skel/.zshrc", &s) == 0) {
if (copy_file("/etc/skel/.zshrc", fname) == 0) {
if (chown(fname, u, g) == -1)
errExit("chown");
}
}
else { //
FILE *fp = fopen(fname, "w");
if (fp) {
fprintf(fp, "\n");
fclose(fp);
if (chown(fname, u, g) == -1)
errExit("chown");
if (chmod(fname, S_IRUSR | S_IWUSR) < 0)
errExit("chown");
}
}
free(fname);
}
// csh
else if (arg_csh) {
// copy skel files
if (asprintf(&fname, "%s/.cshrc", homedir) == -1)
errExit("asprintf");
struct stat s;
// don't copy it if we already have the file
if (stat(fname, &s) == 0)
return;
if (stat("/etc/skel/.cshrc", &s) == 0) {
if (copy_file("/etc/skel/.cshrc", fname) == 0) {
if (chown(fname, u, g) == -1)
errExit("chown");
}
}
else { //
/* coverity[toctou] */
FILE *fp = fopen(fname, "w");
if (fp) {
fprintf(fp, "\n");
fclose(fp);
if (chown(fname, u, g) == -1)
errExit("chown");
if (chmod(fname, S_IRUSR | S_IWUSR) < 0)
errExit("chown");
}
}
free(fname);
}
// bash etc.
else {
// copy skel files
if (asprintf(&fname, "%s/.bashrc", homedir) == -1)
errExit("asprintf");
struct stat s;
// don't copy it if we already have the file
if (stat(fname, &s) == 0)
return;
if (stat("/etc/skel/.bashrc", &s) == 0) {
if (copy_file("/etc/skel/.bashrc", fname) == 0) {
/* coverity[toctou] */
if (chown(fname, u, g) == -1)
errExit("chown");
}
}
free(fname);
}
}
static int store_xauthority(void) {
// put a copy of .Xauthority in MNT_DIR
fs_build_mnt_dir();
char *src;
char *dest;
if (asprintf(&src, "%s/.Xauthority", cfg.homedir) == -1)
errExit("asprintf");
if (asprintf(&dest, "%s/.Xauthority", MNT_DIR) == -1)
errExit("asprintf");
struct stat s;
if (stat(src, &s) == 0) {
int rv = copy_file(src, dest);
if (rv) {
fprintf(stderr, "Warning: cannot transfer .Xauthority in private home directory\n");
return 0;
}
return 1; // file copied
}
return 0;
}
static void copy_xauthority(void) {
// put a copy of .Xauthority in MNT_DIR
fs_build_mnt_dir();
char *src;
char *dest;
if (asprintf(&dest, "%s/.Xauthority", cfg.homedir) == -1)
errExit("asprintf");
if (asprintf(&src, "%s/.Xauthority", MNT_DIR) == -1)
errExit("asprintf");
int rv = copy_file(src, dest);
if (rv)
fprintf(stderr, "Warning: cannot transfer .Xauthority in private home directory\n");
// set permissions and ownership
if (chown(dest, getuid(), getgid()) < 0)
errExit("chown");
if (chmod(dest, S_IRUSR | S_IWUSR) < 0)
errExit("chmod");
// delete the temporary file
unlink(src);
}
// private mode (--private=homedir):
// mount homedir on top of /home/user,
// tmpfs on top of /root in nonroot mode,
// tmpfs on top of /tmp in root mode,
// set skel files,
// restore .Xauthority
void fs_private_homedir(void) {
char *homedir = cfg.homedir;
char *private_homedir = cfg.home_private;
assert(homedir);
assert(private_homedir);
int xflag = store_xauthority();
uid_t u = getuid();
gid_t g = getgid();
struct stat s;
if (stat(homedir, &s) == -1) {
fprintf(stderr, "Error: cannot find user home directory\n");
exit(1);
}
// mount bind private_homedir on top of homedir
if (arg_debug)
printf("Mount-bind %s on top of %s\n", private_homedir, homedir);
if (mount(private_homedir, homedir, NULL, MS_BIND|MS_REC, NULL) < 0)
errExit("mount bind");
// preserve mode and ownership
// if (chown(homedir, s.st_uid, s.st_gid) == -1)
// errExit("mount-bind chown");
// if (chmod(homedir, s.st_mode) == -1)
// errExit("mount-bind chmod");
if (u != 0) {
// mask /root
if (arg_debug)
printf("Mounting a new /root directory\n");
if (mount("tmpfs", "/root", "tmpfs", MS_NOSUID | MS_NODEV | MS_STRICTATIME | MS_REC, "mode=700,gid=0") < 0)
errExit("mounting home directory");
}
else {
// mask /home
if (arg_debug)
printf("Mounting a new /home directory\n");
if (mount("tmpfs", "/home", "tmpfs", MS_NOSUID | MS_NODEV | MS_STRICTATIME | MS_REC, "mode=755,gid=0") < 0)
errExit("mounting home directory");
// mask /tmp only in root mode; KDE keeps all kind of sockets in /tmp!
if (arg_debug)
printf("Mounting a new /tmp directory\n");
if (mount("tmpfs", "/tmp", "tmpfs", MS_NOSUID | MS_NODEV | MS_STRICTATIME | MS_REC, "mode=777,gid=0") < 0)
errExit("mounting tmp directory");
}
skel(homedir, u, g);
if (xflag)
copy_xauthority();
}
// private mode (--private):
// mount tmpfs over /home/user,
// tmpfs on top of /root in nonroot mode,
// tmpfs on top of /tmp in root mode
// set skel files,
// restore .Xauthority
void fs_private(void) {
char *homedir = cfg.homedir;
assert(homedir);
uid_t u = getuid();
gid_t g = getgid();
int xflag = store_xauthority();
// mask /home
if (arg_debug)
printf("Mounting a new /home directory\n");
if (mount("tmpfs", "/home", "tmpfs", MS_NOSUID | MS_NODEV | MS_STRICTATIME | MS_REC, "mode=755,gid=0") < 0)
errExit("mounting home directory");
// mask /root
if (arg_debug)
printf("Mounting a new /root directory\n");
if (mount("tmpfs", "/root", "tmpfs", MS_NOSUID | MS_NODEV | MS_STRICTATIME | MS_REC, "mode=700,gid=0") < 0)
errExit("mounting home directory");
if (u != 0) {
// create /home/user
if (arg_debug)
printf("Create a new user directory\n");
int rv = mkdir(homedir, S_IRWXU);
if (rv == -1)
errExit("mkdir");
if (chown(homedir, u, g) < 0)
errExit("chown");
}
else {
// mask tmp only in root mode; KDE keeps all kind of sockets in /tmp!
if (arg_debug)
printf("Mounting a new /tmp directory\n");
if (mount("tmpfs", "/tmp", "tmpfs", MS_NOSUID | MS_NODEV | MS_STRICTATIME | MS_REC, "mode=777,gid=0") < 0)
errExit("mounting tmp directory");
}
skel(homedir, u, g);
if (xflag)
copy_xauthority();
}
static void check_dir_or_file(const char *name) {
assert(name);
struct stat s;
char *fname;
if (asprintf(&fname, "%s/%s", cfg.homedir, name) == -1)
errExit("asprintf");
if (arg_debug)
printf("Checking %s\n", fname);
if (stat(fname, &s) == -1) {
fprintf(stderr, "Error: file %s not found.\n", fname);
exit(1);
}
// check uid
uid_t uid = getuid();
gid_t gid = getgid();
if (s.st_uid != uid || s.st_gid != gid) {
fprintf(stderr, "Error: only files or directories created by the current user are allowed.\n");
exit(1);
}
// dir or regular file
if (S_ISDIR(s.st_mode) || S_ISREG(s.st_mode)) {
free(fname);
return;
}
if (!is_link(fname)) {
free(fname);
return;
}
fprintf(stderr, "Error: invalid file type, %s.\n", fname);
exit(1);
}
// check directory linst specified by user (--private.keep option) - exit if it fails
void fs_check_home_list(void) {
if (strstr(cfg.home_private_keep, "..")) {
fprintf(stderr, "Error: invalid private.keep list\n");
exit(1);
}
char *dlist = strdup(cfg.home_private_keep);
if (!dlist)
errExit("strdup");
char *ptr = strtok(dlist, ",");
check_dir_or_file(ptr);
while ((ptr = strtok(NULL, ",")) != NULL)
check_dir_or_file(ptr);
free(dlist);
}
// check new private home directory (--private= option) - exit if it fails
void fs_check_private_dir(void) {
// if the directory starts with ~, expand the home directory
if (*cfg.home_private == '~') {
char *tmp;
if (asprintf(&tmp, "%s%s", cfg.homedir, cfg.home_private + 1) == -1)
errExit("asprintf");
cfg.home_private = tmp;
}
if (!is_dir(cfg.home_private) || is_link(cfg.home_private) || strstr(cfg.home_private, "..")) {
fprintf(stderr, "Error: invalid private directory\n");
exit(1);
}
// check home directory and chroot home directory have the same owner
struct stat s2;
int rv = stat(cfg.home_private, &s2);
if (rv < 0) {
fprintf(stderr, "Error: cannot find %s directory\n", cfg.home_private);
exit(1);
}
struct stat s1;
rv = stat(cfg.homedir, &s1);
if (rv < 0) {
fprintf(stderr, "Error: cannot find %s directory, full path name required\n", cfg.homedir);
exit(1);
}
if (s1.st_uid != s2.st_uid) {
printf("Error: the two home directories must have the same owner\n");
exit(1);
}
}
#if 0
static int mkpath(char* file_path, mode_t mode) {
assert(file_path && *file_path);
char* p;
for (p=strchr(file_path+1, '/'); p; p=strchr(p+1, '/')) {
*p='\0';
if (mkdir(file_path, mode)==-1) {
if (errno!=EEXIST) { *p='/'; return -1; }
}
*p='/';
}
return 0;
}
#endif
static void duplicate(char *fname) {
char *cmd;
// copy the file
if (asprintf(&cmd, "cp -a --parents %s/%s %s", cfg.homedir, fname, HOME_DIR) == -1)
errExit("asprintf");
if (arg_debug)
printf("%s\n", cmd);
if (system(cmd))
errExit("system cp -a --parents");
free(cmd);
}
// private mode (--private.keep=list):
// mount homedir on top of /home/user,
// tmpfs on top of /root in nonroot mode,
// tmpfs on top of /tmp in root mode,
// set skel files,
// restore .Xauthority
void fs_private_home_list(void) {
char *homedir = cfg.homedir;
char *private_list = cfg.home_private_keep;
assert(homedir);
assert(private_list);
int xflag = store_xauthority();
uid_t u = getuid();
gid_t g = getgid();
struct stat s;
if (stat(homedir, &s) == -1) {
fprintf(stderr, "Error: cannot find user home directory\n");
exit(1);
}
// create /tmp/firejail/mnt/home directory
fs_build_mnt_dir();
int rv = mkdir(HOME_DIR, S_IRWXU | S_IRWXG | S_IRWXO);
if (rv == -1)
errExit("mkdir");
if (chown(HOME_DIR, u, g) < 0)
errExit("chown");
if (chmod(HOME_DIR, 0755) < 0)
errExit("chmod");
// copy the list of files in the new home directory
// using a new child process without root privileges
pid_t child = fork();
if (child < 0)
errExit("fork");
if (child == 0) {
if (arg_debug)
printf("Copying files in the new home:\n");
// drop privileges
if (setgroups(0, NULL) < 0)
errExit("setgroups");
if (setgid(getgid()) < 0)
errExit("setgid/getgid");
if (setuid(getuid()) < 0)
errExit("setuid/getuid");
// copy the list of files in the new home directory
char *dlist = strdup(cfg.home_private_keep);
if (!dlist)
errExit("strdup");
char *ptr = strtok(dlist, ",");
duplicate(ptr);
while ((ptr = strtok(NULL, ",")) != NULL)
duplicate(ptr);
free(dlist);
exit(0);
}
// wait for the child to finish
waitpid(child, NULL, 0);
// mount bind private_homedir on top of homedir
char *newhome;
if (asprintf(&newhome, "%s%s", HOME_DIR, cfg.homedir) == -1)
errExit("asprintf");
if (arg_debug)
printf("Mount-bind %s on top of %s\n", newhome, homedir);
if (mount(newhome, homedir, NULL, MS_BIND|MS_REC, NULL) < 0)
errExit("mount bind");
// preserve mode and ownership
// if (chown(homedir, s.st_uid, s.st_gid) == -1)
// errExit("mount-bind chown");
// if (chmod(homedir, s.st_mode) == -1)
// errExit("mount-bind chmod");
if (u != 0) {
// mask /root
if (arg_debug)
printf("Mounting a new /root directory\n");
if (mount("tmpfs", "/root", "tmpfs", MS_NOSUID | MS_NODEV | MS_STRICTATIME | MS_REC, "mode=700,gid=0") < 0)
errExit("mounting home directory");
}
else {
// mask /home
if (arg_debug)
printf("Mounting a new /home directory\n");
if (mount("tmpfs", "/home", "tmpfs", MS_NOSUID | MS_NODEV | MS_STRICTATIME | MS_REC, "mode=755,gid=0") < 0)
errExit("mounting home directory");
// mask /tmp only in root mode; KDE keeps all kind of sockets in /tmp!
if (arg_debug)
printf("Mounting a new /tmp directory\n");
if (mount("tmpfs", "/tmp", "tmpfs", MS_NOSUID | MS_NODEV | MS_STRICTATIME | MS_REC, "mode=777,gid=0") < 0)
errExit("mounting tmp directory");
}
skel(homedir, u, g);
if (xflag)
copy_xauthority();
}
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