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/*
* Copyright (C) 2014-2024 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 <sys/file.h>
#include <sys/mount.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <dirent.h>
#include <fcntl.h>
static int tmpfs_mounted = 0;
static void preproc_lock_file(const char *path, int *lockfd_ptr) {
assert(path != NULL);
assert(lockfd_ptr != NULL);
long pid = (long)getpid();
if (arg_debug)
fprintf(stderr, "pid=%ld: locking %s ...\n", pid, path);
if (*lockfd_ptr != -1) {
if (arg_debug)
fprintf(stderr, "pid=%ld: already locked %s\n", pid, path);
return;
}
int lockfd = open(path, O_WRONLY | O_CREAT | O_CLOEXEC, S_IRUSR | S_IWUSR);
if (lockfd == -1) {
fprintf(stderr, "Error: cannot create a lockfile at %s\n", path);
errExit("open");
}
if (fchown(lockfd, 0, 0) == -1) {
fprintf(stderr, "Error: cannot chown root:root %s\n", path);
errExit("fchown");
}
if (flock(lockfd, LOCK_EX) == -1) {
fprintf(stderr, "Error: cannot lock %s\n", path);
errExit("flock");
}
*lockfd_ptr = lockfd;
if (arg_debug)
fprintf(stderr, "pid=%ld: locked %s\n", pid, path);
}
static void preproc_unlock_file(const char *path, int *lockfd_ptr) {
assert(path != NULL);
assert(lockfd_ptr != NULL);
long pid = (long)getpid();
if (arg_debug)
fprintf(stderr, "pid=%ld: unlocking %s ...\n", pid, path);
int lockfd = *lockfd_ptr;
if (lockfd == -1) {
if (arg_debug)
fprintf(stderr, "pid=%ld: already unlocked %s\n", pid, path);
return;
}
if (flock(lockfd, LOCK_UN) == -1) {
fprintf(stderr, "Error: cannot unlock %s\n", path);
errExit("flock");
}
if (close(lockfd) == -1) {
fprintf(stderr, "Error: cannot close %s\n", path);
errExit("close");
}
*lockfd_ptr = -1;
if (arg_debug)
fprintf(stderr, "pid=%ld: unlocked %s\n", pid, path);
}
void preproc_lock_firejail_dir(void) {
preproc_lock_file(RUN_DIRECTORY_LOCK_FILE, &lockfd_directory);
}
void preproc_unlock_firejail_dir(void) {
preproc_unlock_file(RUN_DIRECTORY_LOCK_FILE, &lockfd_directory);
}
void preproc_lock_firejail_network_dir(void) {
preproc_lock_file(RUN_NETWORK_LOCK_FILE, &lockfd_network);
}
void preproc_unlock_firejail_network_dir(void) {
preproc_unlock_file(RUN_NETWORK_LOCK_FILE, &lockfd_network);
}
// build /run/firejail directory
void preproc_build_firejail_dir(void) {
struct stat s;
// CentOS 6 doesn't have /run directory
if (stat(RUN_FIREJAIL_BASEDIR, &s)) {
create_empty_dir_as_root(RUN_FIREJAIL_BASEDIR, 0755);
}
create_empty_dir_as_root(RUN_FIREJAIL_DIR, 0755);
create_empty_dir_as_root(RUN_FIREJAIL_NETWORK_DIR, 0755);
create_empty_dir_as_root(RUN_FIREJAIL_BANDWIDTH_DIR, 0755);
create_empty_dir_as_root(RUN_FIREJAIL_NAME_DIR, 0755);
create_empty_dir_as_root(RUN_FIREJAIL_PROFILE_DIR, 0755);
create_empty_dir_as_root(RUN_FIREJAIL_X11_DIR, 0755);
create_empty_dir_as_root(RUN_FIREJAIL_APPIMAGE_DIR, 0755);
create_empty_dir_as_root(RUN_FIREJAIL_LIB_DIR, 0755);
create_empty_dir_as_root(RUN_MNT_DIR, 0755);
// restricted search permission
// only root should be able to lock files in this directory
create_empty_dir_as_root(RUN_FIREJAIL_SANDBOX_DIR, 0700);
create_empty_dir_as_root(RUN_FIREJAIL_DBUS_DIR, 0755);
fs_remount(RUN_FIREJAIL_DBUS_DIR, MOUNT_NOEXEC, 0);
create_empty_dir_as_root(RUN_RO_DIR, S_IRUSR);
fs_remount(RUN_RO_DIR, MOUNT_READONLY, 0);
create_empty_file_as_root(RUN_RO_FILE, S_IRUSR);
fs_remount(RUN_RO_FILE, MOUNT_READONLY, 0);
}
// build /run/firejail/mnt directory
void preproc_mount_mnt_dir(void) {
// mount tmpfs on top of /run/firejail/mnt
if (!tmpfs_mounted) {
if (arg_debug)
printf("Mounting tmpfs on %s directory\n", RUN_MNT_DIR);
if (mount("tmpfs", RUN_MNT_DIR, "tmpfs", MS_NOSUID | MS_STRICTATIME, "mode=755,gid=0") < 0)
errExit("mounting /run/firejail/mnt");
tmpfs_mounted = 1;
fs_logger2("tmpfs", RUN_MNT_DIR);
// open and mount trace file while there are no user-writable files in RUN_MNT_DIR
if (arg_tracefile)
fs_tracefile();
create_empty_dir_as_root(RUN_SECCOMP_DIR, 0755);
if (arg_seccomp_block_secondary)
copy_file(PATH_SECCOMP_BLOCK_SECONDARY, RUN_SECCOMP_BLOCK_SECONDARY, getuid(), getgid(), 0644); // root needed
else {
//copy default seccomp files
copy_file(PATH_SECCOMP_32, RUN_SECCOMP_32, getuid(), getgid(), 0644); // root needed
}
if (arg_allow_debuggers) {
copy_file(PATH_SECCOMP_DEFAULT_DEBUG, RUN_SECCOMP_CFG, getuid(), getgid(), 0644); // root needed
copy_file(PATH_SECCOMP_DEBUG_32, RUN_SECCOMP_32, getuid(), getgid(), 0644); // root needed
} else
copy_file(PATH_SECCOMP_DEFAULT, RUN_SECCOMP_CFG, getuid(), getgid(), 0644); // root needed
if (arg_memory_deny_write_execute) {
copy_file(PATH_SECCOMP_MDWX, RUN_SECCOMP_MDWX, getuid(), getgid(), 0644); // root needed
copy_file(PATH_SECCOMP_MDWX_32, RUN_SECCOMP_MDWX_32, getuid(), getgid(), 0644); // root needed
}
// as root, create empty RUN_SECCOMP_PROTOCOL, RUN_SECCOMP_NS and RUN_SECCOMP_POSTEXEC files
create_empty_file_as_root(RUN_SECCOMP_PROTOCOL, 0644);
if (set_perms(RUN_SECCOMP_PROTOCOL, getuid(), getgid(), 0644))
errExit("set_perms");
if (cfg.restrict_namespaces) {
copy_file(PATH_SECCOMP_NAMESPACES, RUN_SECCOMP_NS, getuid(), getgid(), 0644); // root needed
copy_file(PATH_SECCOMP_NAMESPACES_32, RUN_SECCOMP_NS_32, getuid(), getgid(), 0644); // root needed
#if 0
create_empty_file_as_root(RUN_SECCOMP_NS, 0644);
if (set_perms(RUN_SECCOMP_NS, getuid(), getgid(), 0644))
errExit("set_perms");
create_empty_file_as_root(RUN_SECCOMP_NS_32, 0644);
if (set_perms(RUN_SECCOMP_NS_32, getuid(), getgid(), 0644))
errExit("set_perms");
#endif
}
create_empty_file_as_root(RUN_SECCOMP_POSTEXEC, 0644);
if (set_perms(RUN_SECCOMP_POSTEXEC, getuid(), getgid(), 0644))
errExit("set_perms");
create_empty_file_as_root(RUN_SECCOMP_POSTEXEC_32, 0644);
if (set_perms(RUN_SECCOMP_POSTEXEC_32, getuid(), getgid(), 0644))
errExit("set_perms");
}
}
static void clean_dir(const char *name, int *pidarr, int start_pid, int max_pids) {
DIR *dir;
if (!(dir = opendir(name))) {
fwarning("cannot clean %s directory\n", name);
return; // we live to fight another day!
}
// clean leftover files
struct dirent *entry;
char *end;
while ((entry = readdir(dir)) != NULL) {
pid_t pid = strtol(entry->d_name, &end, 10);
pid %= max_pids;
if (end == entry->d_name || *end)
continue;
if (pid < start_pid)
continue;
if (pidarr[pid] == 0)
delete_run_files(pid);
}
closedir(dir);
}
// clean run directory
void preproc_clean_run(void) {
int max_pids=32769;
int start_pid = 100;
// extract real max_pids
FILE *fp = fopen("/proc/sys/kernel/pid_max", "re");
if (fp) {
int val;
if (fscanf(fp, "%d", &val) == 1) {
if (val > 4194304) // this is the max value supported on 64 bit Linux kernels
val = 4194304;
if (val >= max_pids)
max_pids = val + 1;
}
fclose(fp);
}
int *pidarr = malloc(max_pids * sizeof(int));
if (!pidarr)
errExit("malloc");
memset(pidarr, 0, max_pids * sizeof(int));
// open /proc directory
DIR *dir;
if (!(dir = opendir("/proc"))) {
// sleep 2 seconds and try again
sleep(2);
if (!(dir = opendir("/proc"))) {
fprintf(stderr, "Error: cannot open /proc directory\n");
exit(1);
}
}
// read /proc and populate pidarr with all active processes
struct dirent *entry;
char *end;
while ((entry = readdir(dir)) != NULL) {
pid_t pid = strtol(entry->d_name, &end, 10);
pid %= max_pids;
if (end == entry->d_name || *end)
continue;
if (pid < start_pid)
continue;
pidarr[pid] = 1;
}
closedir(dir);
// clean profile and name directories
clean_dir(RUN_FIREJAIL_PROFILE_DIR, pidarr, start_pid, max_pids);
clean_dir(RUN_FIREJAIL_NAME_DIR, pidarr, start_pid, max_pids);
free(pidarr);
}
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