/
main.c
2593 lines (2362 loc) · 69.6 KB
/
main.c
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/*
* Copyright (C) 2014-2018 Firejail Authors
*
* 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 "../include/pid.h"
#include "../include/firejail_user.h"
#define _GNU_SOURCE
#include <sys/utsname.h>
#include <sched.h>
#include <sys/mount.h>
#include <sys/wait.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <dirent.h>
#include <pwd.h>
#include <errno.h>
#include <limits.h>
#include <sys/file.h>
#include <sys/prctl.h>
#include <signal.h>
#include <time.h>
#include <net/if.h>
#include <sys/utsname.h>
uid_t firejail_uid = 0;
gid_t firejail_gid = 0;
#define STACK_SIZE (1024 * 1024)
static char child_stack[STACK_SIZE]; // space for child's stack
Config cfg; // configuration
int arg_private = 0; // mount private /home and /tmp directoryu
int arg_private_cache = 0; // mount private home/.cache
int arg_debug = 0; // print debug messages
int arg_debug_blacklists = 0; // print debug messages for blacklists
int arg_debug_whitelists = 0; // print debug messages for whitelists
int arg_debug_private_lib = 0; // print debug messages for private-lib
int arg_nonetwork = 0; // --net=none
int arg_command = 0; // -c
int arg_overlay = 0; // overlay option
int arg_overlay_keep = 0; // place overlay diff in a known directory
int arg_overlay_reuse = 0; // allow the reuse of overlays
int arg_seccomp = 0; // enable default seccomp filter
int arg_seccomp_postexec = 0; // need postexec ld.preload library?
int arg_seccomp_block_secondary = 0; // block any secondary architectures
int arg_caps_default_filter = 0; // enable default capabilities filter
int arg_caps_drop = 0; // drop list
int arg_caps_drop_all = 0; // drop all capabilities
int arg_caps_keep = 0; // keep list
char *arg_caps_list = NULL; // optional caps list
int arg_trace = 0; // syscall tracing support
int arg_tracelog = 0; // blacklist tracing support
int arg_rlimit_cpu = 0; // rlimit max cpu time
int arg_rlimit_nofile = 0; // rlimit nofile
int arg_rlimit_nproc = 0; // rlimit nproc
int arg_rlimit_fsize = 0; // rlimit fsize
int arg_rlimit_sigpending = 0; // rlimit fsize
int arg_rlimit_as = 0; // rlimit as
int arg_nogroups = 0; // disable supplementary groups
int arg_nonewprivs = 0; // set the NO_NEW_PRIVS prctl
int arg_noroot = 0; // create a new user namespace and disable root user
int arg_netfilter; // enable netfilter
int arg_netfilter6; // enable netfilter6
char *arg_netfilter_file = NULL; // netfilter file
char *arg_netfilter6_file = NULL; // netfilter6 file
char *arg_netns = NULL; // "ip netns"-created network namespace to use
int arg_doubledash = 0; // double dash
int arg_shell_none = 0; // run the program directly without a shell
int arg_private_dev = 0; // private dev directory
int arg_keep_dev_shm = 0; // preserve /dev/shm
int arg_private_etc = 0; // private etc directory
int arg_private_opt = 0; // private opt directory
int arg_private_srv = 0; // private srv directory
int arg_private_bin = 0; // private bin directory
int arg_private_tmp = 0; // private tmp directory
int arg_private_lib = 0; // private lib directory
int arg_scan = 0; // arp-scan all interfaces
int arg_whitelist = 0; // whitelist commad
int arg_nosound = 0; // disable sound
int arg_noautopulse = 0; // disable automatic ~/.config/pulse init
int arg_novideo = 0; //disable video devices in /dev
int arg_no3d; // disable 3d hardware acceleration
int arg_quiet = 0; // no output for scripting
int arg_join_network = 0; // join only the network namespace
int arg_join_filesystem = 0; // join only the mount namespace
int arg_nice = 0; // nice value configured
int arg_ipc = 0; // enable ipc namespace
int arg_writable_etc = 0; // writable etc
int arg_writable_var = 0; // writable var
int arg_keep_var_tmp = 0; // don't overwrite /var/tmp
int arg_writable_run_user = 0; // writable /run/user
int arg_writable_var_log = 0; // writable /var/log
int arg_appimage = 0; // appimage
int arg_audit = 0; // audit
char *arg_audit_prog = NULL; // audit
int arg_apparmor = 0; // apparmor
int arg_allow_debuggers = 0; // allow debuggers
int arg_x11_block = 0; // block X11
int arg_x11_xorg = 0; // use X11 security extention
int arg_allusers = 0; // all user home directories visible
int arg_machineid = 0; // preserve /etc/machine-id
int arg_allow_private_blacklist = 0; // blacklist things in private directories
int arg_disable_mnt = 0; // disable /mnt and /media
int arg_noprofile = 0; // use default.profile if none other found/specified
int arg_memory_deny_write_execute = 0; // block writable and executable memory
int arg_notv = 0; // --notv
int arg_nodvd = 0; // --nodvd
int arg_nodbus = 0; // -nodbus
int arg_nou2f = 0; // --nou2f
int login_shell = 0;
int parent_to_child_fds[2];
int child_to_parent_fds[2];
char *fullargv[MAX_ARGS]; // expanded argv for restricted shell
int fullargc = 0;
static pid_t child = 0;
pid_t sandbox_pid;
mode_t orig_umask = 022;
unsigned long long start_timestamp;
static void clear_atexit(void) {
EUID_ROOT();
delete_run_files(getpid());
}
static void myexit(int rv) {
logmsg("exiting...");
if (!arg_command)
fmessage("\nParent is shutting down, bye...\n");
// delete sandbox files in shared memory
EUID_ROOT();
delete_run_files(sandbox_pid);
appimage_clear();
flush_stdin();
exit(rv);
}
static void my_handler(int s){
EUID_ROOT();
fmessage("\nParent received signal %d, shutting down the child process...\n", s);
logsignal(s);
kill(child, SIGTERM);
myexit(1);
}
// return 1 if error, 0 if a valid pid was found
static int extract_pid(const char *name, pid_t *pid) {
int retval = 0;
EUID_ASSERT();
if (!name || strlen(name) == 0) {
fprintf(stderr, "Error: invalid sandbox name\n");
exit(1);
}
EUID_ROOT();
if (name2pid(name, pid)) {
retval = 1;
}
EUID_USER();
return retval;
}
// return 1 if error, 0 if a valid pid was found
static int read_pid(const char *name, pid_t *pid) {
char *endptr;
errno = 0;
long int pidtmp = strtol(name, &endptr, 10);
if ((errno == ERANGE && (pidtmp == LONG_MAX || pidtmp == LONG_MIN))
|| (errno != 0 && pidtmp == 0)) {
return extract_pid(name,pid);
}
// endptr points to '\0' char in name if the entire string is valid
if (endptr == NULL || endptr[0]!='\0') {
return extract_pid(name,pid);
}
*pid =(pid_t)pidtmp;
return 0;
}
static pid_t require_pid(const char *name) {
pid_t pid;
if (read_pid(name,&pid)) {
fprintf(stderr, "Error: cannot find sandbox %s\n", name);
exit(1);
}
return pid;
}
// init configuration
static void init_cfg(int argc, char **argv) {
EUID_ASSERT();
memset(&cfg, 0, sizeof(cfg));
cfg.original_argv = argv;
cfg.original_argc = argc;
cfg.bridge0.devsandbox = "eth0";
cfg.bridge1.devsandbox = "eth1";
cfg.bridge2.devsandbox = "eth2";
cfg.bridge3.devsandbox = "eth3";
// extract user data
EUID_ROOT(); // rise permissions for grsecurity
struct passwd *pw = getpwuid(getuid());
if (!pw)
errExit("getpwuid");
EUID_USER();
cfg.username = strdup(pw->pw_name);
if (!cfg.username)
errExit("strdup");
// build home directory name
cfg.homedir = NULL;
if (pw->pw_dir != NULL) {
cfg.homedir = strdup(pw->pw_dir);
if (!cfg.homedir)
errExit("strdup");
}
else {
fprintf(stderr, "Error: user %s doesn't have a user directory assigned\n", cfg.username);
exit(1);
}
cfg.cwd = getcwd(NULL, 0);
if (!cfg.cwd && errno != ENOENT)
errExit("getcwd");
// check user database
if (!firejail_user_check(cfg.username)) {
fprintf(stderr, "Error: the user is not allowed to use Firejail. "
"Please add the user in %s/firejail.users file, "
"either by running \"sudo firecfg\", or by editing the file directly.\n"
"See \"man firejail-users\" for more details.\n", SYSCONFDIR);
// attempt to run the program as is
run_symlink(argc, argv, 1);
exit(1);
}
// initialize random number generator
sandbox_pid = getpid();
time_t t = time(NULL);
srand(t ^ sandbox_pid);
}
static void check_network(Bridge *br) {
assert(br);
if (br->macvlan == 0) // for bridge devices check network range or arp-scan and assign address
net_configure_sandbox_ip(br);
else if (br->ipsandbox) { // for macvlan check network range
char *rv = in_netrange(br->ipsandbox, br->ip, br->mask);
if (rv) {
fprintf(stderr, "%s", rv);
exit(1);
}
}
}
#ifdef HAVE_USERNS
void check_user_namespace(void) {
EUID_ASSERT();
if (getuid() == 0)
goto errout;
// test user namespaces available in the kernel
struct stat s1;
struct stat s2;
struct stat s3;
if (stat("/proc/self/ns/user", &s1) == 0 &&
stat("/proc/self/uid_map", &s2) == 0 &&
stat("/proc/self/gid_map", &s3) == 0)
arg_noroot = 1;
else
goto errout;
return;
errout:
fwarning("noroot option is not available\n");
arg_noroot = 0;
}
#endif
static void exit_err_feature(const char *feature) {
fprintf(stderr, "Error: %s feature is disabled in Firejail configuration file\n", feature);
exit(1);
}
// run independent commands and exit program
// this function handles command line options such as --version and --help
static void run_cmd_and_exit(int i, int argc, char **argv) {
EUID_ASSERT();
//*************************************
// basic arguments
//*************************************
if (strcmp(argv[i], "--help") == 0 ||
strcmp(argv[i], "-?") == 0) {
usage();
exit(0);
}
else if (strcmp(argv[i], "--version") == 0) {
printf("firejail version %s\n", VERSION);
printf("\n");
print_compiletime_support();
printf("\n");
exit(0);
}
#ifdef HAVE_OVERLAYFS
else if (strcmp(argv[i], "--overlay-clean") == 0) {
if (checkcfg(CFG_OVERLAYFS)) {
if (remove_overlay_directory()) {
fprintf(stderr, "Error: cannot remove overlay directory\n");
exit(1);
}
}
else
exit_err_feature("overlayfs");
exit(0);
}
#endif
#ifdef HAVE_X11
else if (strcmp(argv[i], "--x11") == 0) {
if (checkcfg(CFG_X11)) {
x11_start(argc, argv);
exit(0);
}
else
exit_err_feature("x11");
}
else if (strcmp(argv[i], "--x11=xpra") == 0) {
if (checkcfg(CFG_X11)) {
x11_start_xpra(argc, argv);
exit(0);
}
else
exit_err_feature("x11");
}
else if (strcmp(argv[i], "--x11=xephyr") == 0) {
if (checkcfg(CFG_X11)) {
x11_start_xephyr(argc, argv);
exit(0);
}
else
exit_err_feature("x11");
}
else if (strcmp(argv[i], "--x11=xvfb") == 0) {
if (checkcfg(CFG_X11)) {
x11_start_xvfb(argc, argv);
exit(0);
}
else
exit_err_feature("x11");
}
#endif
#ifdef HAVE_NETWORK
else if (strncmp(argv[i], "--bandwidth=", 12) == 0) {
if (checkcfg(CFG_NETWORK)) {
logargs(argc, argv);
// extract the command
if ((i + 1) == argc) {
fprintf(stderr, "Error: command expected after --bandwidth option\n");
exit(1);
}
char *cmd = argv[i + 1];
if (strcmp(cmd, "status") && strcmp(cmd, "clear") && strcmp(cmd, "set")) {
fprintf(stderr, "Error: invalid --bandwidth command.\nValid commands: set, clear, status.\n");
exit(1);
}
// extract network name
char *dev = NULL;
int down = 0;
int up = 0;
if (strcmp(cmd, "set") == 0 || strcmp(cmd, "clear") == 0) {
// extract device name
if ((i + 2) == argc) {
fprintf(stderr, "Error: network name expected after --bandwidth %s option\n", cmd);
exit(1);
}
dev = argv[i + 2];
// check device name
if (if_nametoindex(dev) == 0) {
fprintf(stderr, "Error: network device %s not found\n", dev);
exit(1);
}
// extract bandwidth
if (strcmp(cmd, "set") == 0) {
if ((i + 4) >= argc) {
fprintf(stderr, "Error: invalid --bandwidth set command\n");
exit(1);
}
down = atoi(argv[i + 3]);
if (down < 0) {
fprintf(stderr, "Error: invalid download speed\n");
exit(1);
}
up = atoi(argv[i + 4]);
if (up < 0) {
fprintf(stderr, "Error: invalid upload speed\n");
exit(1);
}
}
}
// extract pid or sandbox name
pid_t pid = require_pid(argv[i] + 12);
bandwidth_pid(pid, cmd, dev, down, up);
}
else
exit_err_feature("networking");
exit(0);
}
else if (strncmp(argv[i], "--netfilter.print=", 18) == 0) {
// extract pid or sandbox name
pid_t pid = require_pid(argv[i] + 18);
netfilter_print(pid, 0);
exit(0);
}
else if (strncmp(argv[i], "--netfilter6.print=", 19) == 0) {
// extract pid or sandbox name
pid_t pid = require_pid(argv[i] + 19);
netfilter_print(pid, 1);
exit(0);
}
#endif
//*************************************
// independent commands - the program will exit!
//*************************************
#ifdef HAVE_SECCOMP
else if (strcmp(argv[i], "--debug-syscalls") == 0) {
if (checkcfg(CFG_SECCOMP)) {
int rv = sbox_run(SBOX_USER | SBOX_CAPS_NONE | SBOX_SECCOMP, 2, PATH_FSECCOMP, "debug-syscalls");
exit(rv);
}
else
exit_err_feature("seccomp");
}
else if (strcmp(argv[i], "--debug-errnos") == 0) {
if (checkcfg(CFG_SECCOMP)) {
int rv = sbox_run(SBOX_USER | SBOX_CAPS_NONE | SBOX_SECCOMP, 2, PATH_FSECCOMP, "debug-errnos");
exit(rv);
}
else
exit_err_feature("seccomp");
exit(0);
}
else if (strncmp(argv[i], "--seccomp.print=", 16) == 0) {
if (checkcfg(CFG_SECCOMP)) {
// print seccomp filter for a sandbox specified by pid or by name
pid_t pid = require_pid(argv[i] + 16);
seccomp_print_filter(pid);
}
else
exit_err_feature("seccomp");
exit(0);
}
else if (strcmp(argv[i], "--debug-protocols") == 0) {
int rv = sbox_run(SBOX_USER | SBOX_CAPS_NONE | SBOX_SECCOMP, 2, PATH_FSECCOMP, "debug-protocols");
exit(rv);
}
else if (strncmp(argv[i], "--protocol.print=", 17) == 0) {
if (checkcfg(CFG_SECCOMP)) {
// print seccomp filter for a sandbox specified by pid or by name
pid_t pid = require_pid(argv[i] + 17);
protocol_print_filter(pid);
}
else
exit_err_feature("seccomp");
exit(0);
}
#endif
else if (strncmp(argv[i], "--profile.print=", 16) == 0) {
pid_t pid = require_pid(argv[i] + 16);
// print /run/firejail/profile/<PID> file
char *fname;
if (asprintf(&fname, RUN_FIREJAIL_PROFILE_DIR "/%d", pid) == -1)
errExit("asprintf");
FILE *fp = fopen(fname, "r");
if (!fp) {
fprintf(stderr, "Error: sandbox %s not found\n", argv[i] + 16);
exit(1);
}
#define MAXBUF 4096
char buf[MAXBUF];
if (fgets(buf, MAXBUF, fp))
printf("%s", buf);
fclose(fp);
exit(0);
}
else if (strncmp(argv[i], "--cpu.print=", 12) == 0) {
// join sandbox by pid or by name
pid_t pid = require_pid(argv[i] + 12);
cpu_print_filter(pid);
exit(0);
}
else if (strncmp(argv[i], "--apparmor.print=", 12) == 0) {
// join sandbox by pid or by name
pid_t pid = require_pid(argv[i] + 17);
char *pidstr;
if (asprintf(&pidstr, "%u", pid) == -1)
errExit("asprintf");
sbox_run(SBOX_USER| SBOX_CAPS_NONE | SBOX_SECCOMP, 3, PATH_FIREMON, "--apparmor", pidstr);
free(pidstr);
exit(0);
}
else if (strncmp(argv[i], "--caps.print=", 13) == 0) {
// join sandbox by pid or by name
pid_t pid = require_pid(argv[i] + 13);
caps_print_filter(pid);
exit(0);
}
else if (strncmp(argv[i], "--fs.print=", 11) == 0) {
// join sandbox by pid or by name
pid_t pid = require_pid(argv[i] + 11);
fs_logger_print_log(pid);
exit(0);
}
else if (strncmp(argv[i], "--dns.print=", 12) == 0) {
// join sandbox by pid or by name
pid_t pid = require_pid(argv[i] + 12);
net_dns_print(pid);
exit(0);
}
else if (strcmp(argv[i], "--debug-caps") == 0) {
caps_print();
exit(0);
}
else if (strcmp(argv[i], "--list") == 0) {
if (pid_hidepid())
sbox_run(SBOX_ROOT| SBOX_CAPS_HIDEPID | SBOX_SECCOMP, 2, PATH_FIREMON, "--list");
else
sbox_run(SBOX_USER| SBOX_CAPS_NONE | SBOX_SECCOMP, 2, PATH_FIREMON, "--list");
exit(0);
}
else if (strcmp(argv[i], "--tree") == 0) {
if (pid_hidepid())
sbox_run(SBOX_ROOT | SBOX_CAPS_HIDEPID | SBOX_SECCOMP, 2, PATH_FIREMON, "--tree");
else
sbox_run(SBOX_USER | SBOX_CAPS_NONE | SBOX_SECCOMP, 2, PATH_FIREMON, "--tree");
exit(0);
}
else if (strcmp(argv[i], "--top") == 0) {
if (pid_hidepid())
sbox_run(SBOX_ROOT | SBOX_CAPS_HIDEPID | SBOX_SECCOMP | SBOX_ALLOW_STDIN,
2, PATH_FIREMON, "--top");
else
sbox_run(SBOX_USER | SBOX_CAPS_NONE | SBOX_SECCOMP | SBOX_ALLOW_STDIN,
2, PATH_FIREMON, "--top");
exit(0);
}
#ifdef HAVE_NETWORK
else if (strcmp(argv[i], "--netstats") == 0) {
if (checkcfg(CFG_NETWORK)) {
struct stat s;
if (stat("/proc/sys/kernel/grsecurity", &s) == 0 || pid_hidepid())
sbox_run(SBOX_ROOT | SBOX_CAPS_HIDEPID | SBOX_SECCOMP | SBOX_ALLOW_STDIN,
2, PATH_FIREMON, "--netstats");
else
sbox_run(SBOX_USER | SBOX_CAPS_NONE | SBOX_SECCOMP | SBOX_ALLOW_STDIN,
2, PATH_FIREMON, "--netstats");
exit(0);
}
else
exit_err_feature("networking");
}
#endif
#ifdef HAVE_FILE_TRANSFER
else if (strncmp(argv[i], "--get=", 6) == 0) {
if (checkcfg(CFG_FILE_TRANSFER)) {
logargs(argc, argv);
// verify path
if ((i + 2) != argc) {
fprintf(stderr, "Error: invalid --get option, path expected\n");
exit(1);
}
char *path = argv[i + 1];
invalid_filename(path, 0); // no globbing
if (strstr(path, "..")) {
fprintf(stderr, "Error: invalid file name %s\n", path);
exit(1);
}
// get file
pid_t pid = require_pid(argv[i] + 6);
sandboxfs(SANDBOX_FS_GET, pid, path, NULL);
exit(0);
}
else
exit_err_feature("file transfer");
}
else if (strncmp(argv[i], "--put=", 6) == 0) {
if (checkcfg(CFG_FILE_TRANSFER)) {
logargs(argc, argv);
// verify path
if ((i + 3) != argc) {
fprintf(stderr, "Error: invalid --put option, 2 paths expected\n");
exit(1);
}
char *path1 = argv[i + 1];
invalid_filename(path1, 0); // no globbing
if (strstr(path1, "..")) {
fprintf(stderr, "Error: invalid file name %s\n", path1);
exit(1);
}
char *path2 = argv[i + 2];
invalid_filename(path2, 0); // no globbing
if (strstr(path2, "..")) {
fprintf(stderr, "Error: invalid file name %s\n", path2);
exit(1);
}
// get file
pid_t pid = require_pid(argv[i] + 6);
sandboxfs(SANDBOX_FS_PUT, pid, path1, path2);
exit(0);
}
else
exit_err_feature("file transfer");
}
else if (strncmp(argv[i], "--ls=", 5) == 0) {
if (checkcfg(CFG_FILE_TRANSFER)) {
logargs(argc, argv);
// verify path
if ((i + 2) != argc) {
fprintf(stderr, "Error: invalid --ls option, path expected\n");
exit(1);
}
char *path = argv[i + 1];
invalid_filename(path, 0); // no globbing
if (strstr(path, "..")) {
fprintf(stderr, "Error: invalid file name %s\n", path);
exit(1);
}
// list directory contents
pid_t pid = require_pid(argv[i] + 5);
sandboxfs(SANDBOX_FS_LS, pid, path, NULL);
exit(0);
}
else
exit_err_feature("file transfer");
}
#endif
else if (strncmp(argv[i], "--join=", 7) == 0) {
if (checkcfg(CFG_JOIN) || getuid() == 0) {
logargs(argc, argv);
if (arg_shell_none) {
if (argc <= (i+1)) {
fprintf(stderr, "Error: --shell=none set, but no command specified\n");
exit(1);
}
cfg.original_program_index = i + 1;
}
if (!cfg.shell && !arg_shell_none)
cfg.shell = guess_shell();
// join sandbox by pid or by name
pid_t pid = require_pid(argv[i] + 7);
join(pid, argc, argv, i + 1);
exit(0);
}
else
exit_err_feature("join");
}
else if (strncmp(argv[i], "--join-or-start=", 16) == 0) {
// NOTE: this is first part of option handler,
// sandbox name is set in other part
logargs(argc, argv);
if (arg_shell_none) {
if (argc <= (i+1)) {
fprintf(stderr, "Error: --shell=none set, but no command specified\n");
exit(1);
}
cfg.original_program_index = i + 1;
}
// try to join by name only
pid_t pid;
if (!read_pid(argv[i] + 16, &pid)) {
if (!cfg.shell && !arg_shell_none)
cfg.shell = guess_shell();
join(pid, argc, argv, i + 1);
exit(0);
}
// if there no such sandbox continue argument processing
}
#ifdef HAVE_NETWORK
else if (strncmp(argv[i], "--join-network=", 15) == 0) {
if (checkcfg(CFG_NETWORK)) {
logargs(argc, argv);
arg_join_network = 1;
if (getuid() != 0) {
fprintf(stderr, "Error: --join-network is only available to root user\n");
exit(1);
}
if (!cfg.shell && !arg_shell_none)
cfg.shell = guess_shell();
// join sandbox by pid or by name
pid_t pid = require_pid(argv[i] + 15);
join(pid, argc, argv, i + 1);
}
else
exit_err_feature("networking");
exit(0);
}
#endif
else if (strncmp(argv[i], "--join-filesystem=", 18) == 0) {
logargs(argc, argv);
arg_join_filesystem = 1;
if (getuid() != 0) {
fprintf(stderr, "Error: --join-filesystem is only available to root user\n");
exit(1);
}
if (!cfg.shell && !arg_shell_none)
cfg.shell = guess_shell();
// join sandbox by pid or by name
pid_t pid = require_pid(argv[i] + 18);
join(pid, argc, argv, i + 1);
exit(0);
}
else if (strncmp(argv[i], "--shutdown=", 11) == 0) {
logargs(argc, argv);
// shutdown sandbox by pid or by name
pid_t pid = require_pid(argv[i] + 11);
shut(pid);
exit(0);
}
}
char *guess_shell(void) {
char *shell = NULL;
struct stat s;
shell = getenv("SHELL");
if (shell) {
// TODO: handle rogue shell variables?
if (stat(shell, &s) == 0 && access(shell, R_OK) == 0) {
return shell;
}
}
// shells in order of preference
char *shells[] = {"/bin/bash", "/bin/csh", "/usr/bin/zsh", "/bin/sh", "/bin/ash", NULL };
int i = 0;
while (shells[i] != NULL) {
// access call checks as real UID/GID, not as effective UID/GID
if (stat(shells[i], &s) == 0 && access(shells[i], R_OK) == 0) {
shell = shells[i];
break;
}
i++;
}
return shell;
}
static int check_arg(int argc, char **argv, const char *argument, int strict) {
int i;
int found = 0;
for (i = 1; i < argc; i++) {
if (strict) {
if (strcmp(argv[i], argument) == 0) {
found = 1;
break;
}
}
else {
if (strncmp(argv[i], argument, strlen(argument)) == 0) {
found = 1;
break;
}
}
// detect end of firejail params
if (strcmp(argv[i], "--") == 0)
break;
if (strncmp(argv[i], "--", 2) != 0)
break;
}
return found;
}
static void run_builder(int argc, char **argv) {
EUID_ASSERT();
(void) argc;
// drop privileges
EUID_ROOT();
if (setgid(getgid()) < 0)
errExit("setgid/getgid");
if (setuid(getuid()) < 0)
errExit("setuid/getuid");
assert(getenv("LD_PRELOAD") == NULL);
umask(orig_umask);
argv[0] = LIBDIR "/firejail/fbuilder";
execvp(argv[0], argv);
perror("execvp");
exit(1);
}
//*******************************************
// Main program
//*******************************************
int main(int argc, char **argv) {
int i;
int prog_index = -1; // index in argv where the program command starts
int lockfd_network = -1;
int lockfd_directory = -1;
int option_cgroup = 0;
int custom_profile = 0; // custom profile loaded
int arg_seccomp_cmdline = 0; // seccomp requested on command line (used to break out of --chroot)
int arg_caps_cmdline = 0; // caps requested on command line (used to break out of --chroot)
// drop permissions by default and rise them when required
EUID_INIT();
EUID_USER();
// sanitize the umask
orig_umask = umask(022);
// check if the user is allowed to use firejail
init_cfg(argc, argv);
// get starting timestamp, process --quiet
start_timestamp = getticks();
if (check_arg(argc, argv, "--quiet", 1))
arg_quiet = 1;
// cleanup at exit
EUID_ROOT();
atexit(clear_atexit);
// build /run/firejail directory structure
preproc_build_firejail_dir();
char *container_name = getenv("container");
if (!container_name || strcmp(container_name, "firejail")) {
lockfd_directory = open(RUN_DIRECTORY_LOCK_FILE, O_WRONLY | O_CREAT, S_IRUSR | S_IWUSR);
if (lockfd_directory != -1) {
int rv = fchown(lockfd_directory, 0, 0);
(void) rv;
flock(lockfd_directory, LOCK_EX);
}
preproc_clean_run();
flock(lockfd_directory, LOCK_UN);
close(lockfd_directory);
}
EUID_USER();
// process allow-debuggers
if (check_arg(argc, argv, "--allow-debuggers", 1)) {
// check kernel version
struct utsname u;
int rv = uname(&u);
if (rv != 0)
errExit("uname");
int major;
int minor;
if (2 != sscanf(u.release, "%d.%d", &major, &minor)) {
fprintf(stderr, "Error: cannot extract Linux kernel version: %s\n", u.version);
exit(1);
}
if (major < 4 || (major == 4 && minor < 8)) {
fprintf(stderr, "Error: --allow-debuggers is disabled on Linux kernels prior to 4.8. "
"A bug in ptrace call allows a full bypass of the seccomp filter. "
"Your current kernel version is %d.%d.\n", major, minor);
exit(1);
}
arg_allow_debuggers = 1;
char *cmd = strdup("noblacklist ${PATH}/strace");
if (!cmd)
errExit("strdup");
profile_add(cmd);
}
// profile builder
if (check_arg(argc, argv, "--build", 0)) // supports both --build and --build=filename
run_builder(argc, argv); // this function will not return
// check argv[0] symlink wrapper if this is not a login shell
if (*argv[0] != '-')
run_symlink(argc, argv, 0); // if symlink detected, this function will not return
// check if we already have a sandbox running
// If LXC is detected, start firejail sandbox
// otherwise try to detect a PID namespace by looking under /proc for specific kernel processes and:
// - start the application in a /bin/bash shell
if (check_namespace_virt() == 0) {
EUID_ROOT();
int rv = check_kernel_procs();
EUID_USER();
if (rv == 0) {
if (check_arg(argc, argv, "--version", 1)) {
printf("firejail version %s\n", VERSION);
exit(0);
}
// start the program directly without sandboxing
run_no_sandbox(argc, argv);
// it will never get here!
assert(0);
}
}
EUID_ASSERT();
// check firejail directories
EUID_ROOT();
delete_run_files(sandbox_pid);
EUID_USER();
//check if the parent is sshd daemon
int parent_sshd = 0;
{
pid_t ppid = getppid();
EUID_ROOT();
char *comm = pid_proc_comm(ppid);
EUID_USER();
if (comm) {
if (strcmp(comm, "sshd") == 0) {
arg_quiet = 1;
parent_sshd = 1;
#ifdef DEBUG_RESTRICTED_SHELL
{EUID_ROOT();
FILE *fp = fopen("/firelog", "w");
if (fp) {
int i;
fprintf(fp, "argc %d: ", argc);
for (i = 0; i < argc; i++)
fprintf(fp, "#%s# ", argv[i]);
fprintf(fp, "\n");
fclose(fp);
}
EUID_USER();}
#endif
// run sftp and scp directly without any sandboxing
// regular login has argv[0] == "-firejail"
if (*argv[0] != '-') {
if (strcmp(argv[1], "-c") == 0 && argc > 2) {
if (strcmp(argv[2], "/usr/lib/openssh/sftp-server") == 0 ||
strncmp(argv[2], "scp ", 4) == 0) {
#ifdef DEBUG_RESTRICTED_SHELL
{EUID_ROOT();
FILE *fp = fopen("/firelog", "a");
if (fp) {
fprintf(fp, "run without a sandbox\n");