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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 <sys/mount.h>
#include <sys/stat.h>
#include <sys/statvfs.h>
#include <sys/wait.h>
#include <linux/limits.h>
#include <fnmatch.h>
#include <glob.h>
#include <dirent.h>
#include <errno.h>
#include <fcntl.h>
// check noblacklist statements not matched by a proper blacklist in disable-*.inc files
//#define TEST_NO_BLACKLIST_MATCHING
static void fs_rdwr(const char *dir);
//***********************************************
// process profile file
//***********************************************
typedef enum {
BLACKLIST_FILE,
BLACKLIST_NOLOG,
MOUNT_READONLY,
MOUNT_TMPFS,
MOUNT_NOEXEC,
MOUNT_RDWR,
OPERATION_MAX
} OPERATION;
typedef enum {
UNSUCCESSFUL,
SUCCESSFUL
} LAST_DISABLE_OPERATION;
LAST_DISABLE_OPERATION last_disable = UNSUCCESSFUL;
static void disable_file(OPERATION op, const char *filename) {
assert(filename);
assert(op <OPERATION_MAX);
last_disable = UNSUCCESSFUL;
// Resolve all symlinks
char* fname = realpath(filename, NULL);
if (fname == NULL && errno != EACCES) {
return;
}
if (fname == NULL && errno == EACCES) {
if (arg_debug)
printf("Debug: no access to file %s, forcing mount\n", filename);
// realpath and stat funtions will fail on FUSE filesystems
// they don't seem to like a uid of 0
// force mounting
int rv = mount(RUN_RO_DIR, filename, "none", MS_BIND, "mode=400,gid=0");
if (rv == 0)
last_disable = SUCCESSFUL;
else {
rv = mount(RUN_RO_FILE, filename, "none", MS_BIND, "mode=400,gid=0");
if (rv == 0)
last_disable = SUCCESSFUL;
}
if (last_disable == SUCCESSFUL) {
if (arg_debug)
printf("Disable %s\n", filename);
if (op == BLACKLIST_FILE)
fs_logger2("blacklist", filename);
else
fs_logger2("blacklist-nolog", filename);
}
else {
if (arg_debug)
printf("Warning (blacklisting): %s is an invalid file, skipping...\n", filename);
}
return;
}
// if the file is not present, do nothing
struct stat s;
if (fname == NULL)
return;
if (stat(fname, &s) == -1) {
if (arg_debug)
fwarning("%s does not exist, skipping...\n", fname);
free(fname);
return;
}
// modify the file
if (op == BLACKLIST_FILE || op == BLACKLIST_NOLOG) {
// some distros put all executables under /usr/bin and make /bin a symbolic link
if ((strcmp(fname, "/bin") == 0 || strcmp(fname, "/usr/bin") == 0) &&
is_link(filename) &&
S_ISDIR(s.st_mode)) {
fwarning("%s directory link was not blacklisted\n", filename);
}
else {
if (arg_debug) {
if (strcmp(filename, fname))
printf("Disable %s (requested %s)\n", fname, filename);
else
printf("Disable %s\n", fname);
}
else if (arg_debug_blacklists) {
printf("Disable %s", fname);
if (op == BLACKLIST_FILE)
printf("\n");
else
printf(" - no logging\n");
}
if (S_ISDIR(s.st_mode)) {
if (mount(RUN_RO_DIR, fname, "none", MS_BIND, "mode=400,gid=0") < 0)
errExit("disable file");
}
else {
if (mount(RUN_RO_FILE, fname, "none", MS_BIND, "mode=400,gid=0") < 0)
errExit("disable file");
}
last_disable = SUCCESSFUL;
if (op == BLACKLIST_FILE)
fs_logger2("blacklist", fname);
else
fs_logger2("blacklist-nolog", fname);
}
}
else if (op == MOUNT_READONLY) {
if (arg_debug)
printf("Mounting read-only %s\n", fname);
fs_rdonly(fname);
// todo: last_disable = SUCCESSFUL;
}
else if (op == MOUNT_RDWR) {
if (arg_debug)
printf("Mounting read-only %s\n", fname);
fs_rdwr(fname);
// todo: last_disable = SUCCESSFUL;
}
else if (op == MOUNT_NOEXEC) {
if (arg_debug)
printf("Mounting noexec %s\n", fname);
fs_noexec(fname);
// todo: last_disable = SUCCESSFUL;
}
else if (op == MOUNT_TMPFS) {
if (S_ISDIR(s.st_mode)) {
if (arg_debug)
printf("Mounting tmpfs on %s\n", fname);
// preserve owner and mode for the directory
if (mount("tmpfs", fname, "tmpfs", MS_NOSUID | MS_NODEV | MS_STRICTATIME | MS_REC, 0) < 0)
errExit("mounting tmpfs");
/* coverity[toctou] */
if (chown(fname, s.st_uid, s.st_gid) == -1)
errExit("mounting tmpfs chown");
if (chmod(fname, s.st_mode) == -1)
errExit("mounting tmpfs chmod");
last_disable = SUCCESSFUL;
fs_logger2("tmpfs", fname);
}
else
fwarning("%s is not a directory; cannot mount a tmpfs on top of it.\n", fname);
}
else
assert(0);
free(fname);
}
#ifdef TEST_NO_BLACKLIST_MATCHING
static int nbcheck_start = 0;
static size_t nbcheck_size = 0;
static int *nbcheck = NULL;
#endif
// Treat pattern as a shell glob pattern and blacklist matching files
static void globbing(OPERATION op, const char *pattern, const char *noblacklist[], size_t noblacklist_len) {
assert(pattern);
#ifdef TEST_NO_BLACKLIST_MATCHING
if (nbcheck_start == 0) {
nbcheck_start = 1;
nbcheck_size = noblacklist_len;
nbcheck = malloc(sizeof(int) * noblacklist_len);
if (nbcheck == NULL)
errExit("malloc");
memset(nbcheck, 0, sizeof(int) * noblacklist_len);
}
#endif
glob_t globbuf;
// Profiles contain blacklists for files that might not exist on a user's machine.
// GLOB_NOCHECK makes that okay.
int globerr = glob(pattern, GLOB_NOCHECK | GLOB_NOSORT | GLOB_PERIOD, NULL, &globbuf);
if (globerr) {
fprintf(stderr, "Error: failed to glob pattern %s\n", pattern);
exit(1);
}
size_t i, j;
for (i = 0; i < globbuf.gl_pathc; i++) {
char *path = globbuf.gl_pathv[i];
assert(path);
// /home/me/.* can glob to /home/me/.. which would blacklist /home/
const char *base = gnu_basename(path);
if (strcmp(base, ".") == 0 || strcmp(base, "..") == 0)
continue;
// noblacklist is expected to be short in normal cases, so stupid and correct brute force is okay
bool okay_to_blacklist = true;
for (j = 0; j < noblacklist_len; j++) {
int result = fnmatch(noblacklist[j], path, FNM_PATHNAME);
if (result == FNM_NOMATCH)
continue;
else if (result == 0) {
okay_to_blacklist = false;
#ifdef TEST_NO_BLACKLIST_MATCHING
if (j < nbcheck_size) // noblacklist checking
nbcheck[j] = 1;
#endif
break;
}
else {
fprintf(stderr, "Error: failed to compare path %s with pattern %s\n", path, noblacklist[j]);
exit(1);
}
}
if (okay_to_blacklist)
disable_file(op, path);
else if (arg_debug)
printf("Not blacklist %s\n", path);
}
globfree(&globbuf);
}
// blacklist files or directories by mounting empty files on top of them
void fs_blacklist(void) {
char *homedir = cfg.homedir;
assert(homedir);
ProfileEntry *entry = cfg.profile;
if (!entry)
return;
size_t noblacklist_c = 0;
size_t noblacklist_m = 32;
char **noblacklist = calloc(noblacklist_m, sizeof(*noblacklist));
if (noblacklist == NULL)
errExit("failed allocating memory for noblacklist entries");
while (entry) {
OPERATION op = OPERATION_MAX;
char *ptr;
// whitelist commands handled by fs_whitelist()
if (strncmp(entry->data, "whitelist ", 10) == 0 ||
strncmp(entry->data, "nowhitelist ", 12) == 0 ||
*entry->data == '\0') {
entry = entry->next;
continue;
}
// process bind command
if (strncmp(entry->data, "bind ", 5) == 0) {
struct stat s;
char *dname1 = entry->data + 5;
char *dname2 = split_comma(dname1);
if (dname2 == NULL ||
stat(dname1, &s) == -1 ||
stat(dname2, &s) == -1) {
fprintf(stderr, "Error: invalid bind command, directory missing\n");
entry = entry->next;
continue;
}
// mount --bind olddir newdir
if (arg_debug)
printf("Mount-bind %s on top of %s\n", dname1, dname2);
// preserve dname2 mode and ownership
if (mount(dname1, dname2, NULL, MS_BIND|MS_REC, NULL) < 0)
errExit("mount bind");
/* coverity[toctou] */
if (set_perms(dname2, s.st_uid, s.st_gid,s.st_mode))
errExit("set_perms");
entry = entry->next;
continue;
}
// Process noblacklist command
if (strncmp(entry->data, "noblacklist ", 12) == 0) {
char **enames;
int i;
if (strncmp(entry->data + 12, "${PATH}", 7) == 0) {
// expand ${PATH} macro
char **paths = build_paths();
unsigned int npaths = count_paths();
enames = calloc(npaths, sizeof(char *));
if (!enames)
errExit("calloc");
for (i = 0; paths[i]; i++) {
if (asprintf(&enames[i], "%s%s", paths[i],
entry->data + 19) == -1)
errExit("asprintf");
}
assert(enames[npaths-1] == 0);
}
else {
// expand ${HOME} macro if found or pass as is
enames = calloc(2, sizeof(char *));
if (!enames)
errExit("calloc");
enames[0] = expand_home(entry->data + 12, homedir);
assert(enames[1] == 0);
}
for (i = 0; enames[i]; i++) {
if (noblacklist_c >= noblacklist_m) {
noblacklist_m *= 2;
noblacklist = realloc(noblacklist, sizeof(*noblacklist) * noblacklist_m);
if (noblacklist == NULL)
errExit("failed increasing memory for noblacklist entries");
}
noblacklist[noblacklist_c++] = enames[i];
}
free(enames);
entry = entry->next;
continue;
}
// process blacklist command
if (strncmp(entry->data, "blacklist ", 10) == 0) {
ptr = entry->data + 10;
op = BLACKLIST_FILE;
}
else if (strncmp(entry->data, "blacklist-nolog ", 16) == 0) {
ptr = entry->data + 16;
op = BLACKLIST_NOLOG;
}
else if (strncmp(entry->data, "read-only ", 10) == 0) {
ptr = entry->data + 10;
op = MOUNT_READONLY;
}
else if (strncmp(entry->data, "read-write ", 11) == 0) {
ptr = entry->data + 11;
op = MOUNT_RDWR;
}
else if (strncmp(entry->data, "noexec ", 7) == 0) {
ptr = entry->data + 7;
op = MOUNT_NOEXEC;
}
else if (strncmp(entry->data, "tmpfs ", 6) == 0) {
ptr = entry->data + 6;
op = MOUNT_TMPFS;
}
else if (strncmp(entry->data, "mkdir ", 6) == 0) {
EUID_USER();
fs_mkdir(entry->data + 6);
EUID_ROOT();
entry = entry->next;
continue;
}
else if (strncmp(entry->data, "mkfile ", 7) == 0) {
EUID_USER();
fs_mkfile(entry->data + 7);
EUID_ROOT();
entry = entry->next;
continue;
}
else {
fprintf(stderr, "Error: invalid profile line %s\n", entry->data);
entry = entry->next;
continue;
}
// replace home macro in blacklist array
char *new_name = expand_home(ptr, homedir);
ptr = new_name;
// expand path macro - look for the file in /usr/local/bin, /usr/local/sbin, /bin, /usr/bin, /sbin and /usr/sbin directories
if (ptr) {
if (strncmp(ptr, "${PATH}", 7) == 0) {
char *fname = ptr + 7;
size_t fname_len = strlen(fname);
char **paths = build_paths(); //{"/usr/local/bin", "/usr/local/sbin", "/bin", "/usr/bin/", "/sbin", "/usr/sbin", NULL};
int i = 0;
while (paths[i] != NULL) {
char *path = paths[i];
i++;
char newname[strlen(path) + fname_len + 1];
sprintf(newname, "%s%s", path, fname);
globbing(op, newname, (const char**)noblacklist, noblacklist_c);
}
}
else
globbing(op, ptr, (const char**)noblacklist, noblacklist_c);
}
if (new_name)
free(new_name);
entry = entry->next;
}
size_t i;
#ifdef TEST_NO_BLACKLIST_MATCHING
// noblacklist checking
for (i = 0; i < nbcheck_size; i++)
if (!arg_quiet && !nbcheck[i])
printf("TESTING warning: noblacklist %s not matched by a proper blacklist command in disable*.inc\n",
noblacklist[i]);
// free memory
if (nbcheck) {
free(nbcheck);
nbcheck = NULL;
nbcheck_size = 0;
}
#endif
for (i = 0; i < noblacklist_c; i++)
free(noblacklist[i]);
free(noblacklist);
}
static int get_mount_flags(const char *path, unsigned long *flags) {
struct statvfs buf;
if (statvfs(path, &buf) < 0)
return -errno;
*flags = buf.f_flag;
return 0;
}
//***********************************************
// mount namespace
//***********************************************
// remount a directory read-only
void fs_rdonly(const char *dir) {
assert(dir);
// check directory exists
struct stat s;
int rv = stat(dir, &s);
if (rv == 0) {
unsigned long flags = 0;
get_mount_flags(dir, &flags);
if ((flags & MS_RDONLY) == MS_RDONLY)
return;
flags |= MS_RDONLY;
// mount --bind /bin /bin
// mount --bind -o remount,ro /bin
if (mount(dir, dir, NULL, MS_BIND|MS_REC, NULL) < 0 ||
mount(NULL, dir, NULL, flags|MS_BIND|MS_REMOUNT|MS_REC, NULL) < 0)
errExit("mount read-only");
fs_logger2("read-only", dir);
}
}
static void fs_rdwr(const char *dir) {
assert(dir);
// check directory exists and ensure we have a resolved path
// the resolved path allows to run a sanity check after the mount
char *path = realpath(dir, NULL);
if (path == NULL)
return;
// allow only user owned directories, except the user is root
uid_t u = getuid();
struct stat s;
int rv = stat(path, &s);
if (rv) {
free(path);
return;
}
if (u != 0 && s.st_uid != u) {
fwarning("you are not allowed to change %s to read-write\n", path);
free(path);
return;
}
// mount --bind /bin /bin
// mount --bind -o remount,rw /bin
unsigned long flags = 0;
get_mount_flags(path, &flags);
if ((flags & MS_RDONLY) == 0) {
free(path);
return;
}
flags &= ~MS_RDONLY;
if (mount(path, path, NULL, MS_BIND|MS_REC, NULL) < 0 ||
mount(NULL, path, NULL, flags|MS_BIND|MS_REMOUNT|MS_REC, NULL) < 0)
errExit("mount read-write");
fs_logger2("read-write", path);
// run a check on /proc/self/mountinfo to validate the mount
MountData *mptr = get_last_mount();
if (strncmp(mptr->dir, path, strlen(path)) != 0)
errLogExit("invalid read-write mount");
free(path);
}
void fs_noexec(const char *dir) {
assert(dir);
// check directory exists
struct stat s;
int rv = stat(dir, &s);
if (rv == 0) {
// mount --bind /bin /bin
// mount --bind -o remount,ro /bin
unsigned long flags = 0;
get_mount_flags(dir, &flags);
if ((flags & (MS_NOEXEC|MS_NODEV|MS_NOSUID)) == (MS_NOEXEC|MS_NODEV|MS_NOSUID))
return;
flags |= MS_NOEXEC|MS_NODEV|MS_NOSUID;
if (mount(dir, dir, NULL, MS_BIND|MS_REC, NULL) < 0 ||
mount(NULL, dir, NULL, flags|MS_BIND|MS_REMOUNT|MS_REC, NULL) < 0)
errExit("mount noexec");
fs_logger2("noexec", dir);
}
}
// Disable /mnt, /media, /run/mount and /run/media access
void fs_mnt(void) {
disable_file(BLACKLIST_FILE, "/mnt");
disable_file(BLACKLIST_FILE, "/media");
disable_file(BLACKLIST_FILE, "/run/mount");
disable_file(BLACKLIST_FILE, "//run/media");
}
// mount /proc and /sys directories
void fs_proc_sys_dev_boot(void) {
if (arg_debug)
printf("Remounting /proc and /proc/sys filesystems\n");
if (mount("proc", "/proc", "proc", MS_NOSUID | MS_NOEXEC | MS_NODEV | MS_REC, NULL) < 0)
errExit("mounting /proc");
fs_logger("remount /proc");
// remount /proc/sys readonly
if (mount("/proc/sys", "/proc/sys", NULL, MS_BIND | MS_REC, NULL) < 0 ||
mount(NULL, "/proc/sys", NULL, MS_BIND | MS_REMOUNT | MS_RDONLY | MS_NOSUID | MS_NOEXEC | MS_NODEV | MS_REC, NULL) < 0)
errExit("mounting /proc/sys");
fs_logger("read-only /proc/sys");
/* Mount a version of /sys that describes the network namespace */
if (arg_debug)
printf("Remounting /sys directory\n");
if (umount2("/sys", MNT_DETACH) < 0)
fwarning("failed to unmount /sys\n");
if (mount("sysfs", "/sys", "sysfs", MS_RDONLY|MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_REC, NULL) < 0)
fwarning("failed to mount /sys\n");
else
fs_logger("remount /sys");
disable_file(BLACKLIST_FILE, "/sys/firmware");
disable_file(BLACKLIST_FILE, "/sys/hypervisor");
{ // allow user access to some directories in /sys/ by specifying 'noblacklist' option
EUID_USER();
profile_add("blacklist /sys/fs");
profile_add("blacklist /sys/module");
EUID_ROOT();
}
disable_file(BLACKLIST_FILE, "/sys/power");
disable_file(BLACKLIST_FILE, "/sys/kernel/debug");
disable_file(BLACKLIST_FILE, "/sys/kernel/vmcoreinfo");
disable_file(BLACKLIST_FILE, "/sys/kernel/uevent_helper");
// various /proc/sys files
disable_file(BLACKLIST_FILE, "/proc/sys/security");
disable_file(BLACKLIST_FILE, "/proc/sys/efi/vars");
disable_file(BLACKLIST_FILE, "/proc/sys/fs/binfmt_misc");
disable_file(BLACKLIST_FILE, "/proc/sys/kernel/core_pattern");
disable_file(BLACKLIST_FILE, "/proc/sys/kernel/modprobe");
disable_file(BLACKLIST_FILE, "/proc/sysrq-trigger");
disable_file(BLACKLIST_FILE, "/proc/sys/kernel/hotplug");
disable_file(BLACKLIST_FILE, "/proc/sys/vm/panic_on_oom");
// various /proc files
disable_file(BLACKLIST_FILE, "/proc/irq");
disable_file(BLACKLIST_FILE, "/proc/bus");
disable_file(BLACKLIST_FILE, "/proc/config.gz");
disable_file(BLACKLIST_FILE, "/proc/sched_debug");
disable_file(BLACKLIST_FILE, "/proc/timer_list");
disable_file(BLACKLIST_FILE, "/proc/timer_stats");
disable_file(BLACKLIST_FILE, "/proc/kcore");
disable_file(BLACKLIST_FILE, "/proc/kallsyms");
disable_file(BLACKLIST_FILE, "/proc/mem");
disable_file(BLACKLIST_FILE, "/proc/kmem");
// remove kernel symbol information
if (!arg_allow_debuggers) {
disable_file(BLACKLIST_FILE, "/usr/src/linux");
disable_file(BLACKLIST_FILE, "/lib/modules");
disable_file(BLACKLIST_FILE, "/usr/lib/debug");
disable_file(BLACKLIST_FILE, "/boot");
}
// disable /selinux
disable_file(BLACKLIST_FILE, "/selinux");
// disable /dev/port
disable_file(BLACKLIST_FILE, "/dev/port");
// disable various ipc sockets in /run/user
if (!arg_writable_run_user) {
struct stat s;
char *fname;
if (asprintf(&fname, "/run/user/%d", getuid()) == -1)
errExit("asprintf");
if (is_dir(fname)) { // older distros don't have this directory
// disable /run/user/{uid}/gnupg
char *fnamegpg;
if (asprintf(&fnamegpg, "/run/user/%d/gnupg", getuid()) == -1)
errExit("asprintf");
if (stat(fnamegpg, &s) == -1) {
pid_t child = fork();
if (child < 0)
errExit("fork");
if (child == 0) {
// drop privileges
drop_privs(0);
if (mkdir(fnamegpg, 0700) == 0) {
if (chmod(fnamegpg, 0700) == -1)
{;} // do nothing
}
#ifdef HAVE_GCOV
__gcov_flush();
#endif
_exit(0);
}
// wait for the child to finish
waitpid(child, NULL, 0);
fs_logger2("create", fnamegpg);
}
if (stat(fnamegpg, &s) == 0)
disable_file(BLACKLIST_FILE, fnamegpg);
free(fnamegpg);
// disable /run/user/{uid}/systemd
char *fnamesysd;
if (asprintf(&fnamesysd, "/run/user/%d/systemd", getuid()) == -1)
errExit("asprintf");
if (stat(fnamesysd, &s) == -1) {
pid_t child = fork();
if (child < 0)
errExit("fork");
if (child == 0) {
// drop privileges
drop_privs(0);
if (mkdir(fnamesysd, 0755) == 0) {
if (chmod(fnamesysd, 0755) == -1)
{;} // do nothing
}
#ifdef HAVE_GCOV
__gcov_flush();
#endif
_exit(0);
}
// wait for the child to finish
waitpid(child, NULL, 0);
fs_logger2("create", fnamesysd);
}
if (stat(fnamesysd, &s) == 0)
disable_file(BLACKLIST_FILE, fnamesysd);
free(fnamesysd);
}
free(fname);
}
if (getuid() != 0) {
// disable /dev/kmsg and /proc/kmsg
disable_file(BLACKLIST_FILE, "/dev/kmsg");
disable_file(BLACKLIST_FILE, "/proc/kmsg");
}
}
// disable firejail configuration in /etc/firejail and in ~/.config/firejail
static void disable_config(void) {
struct stat s;
char *fname;
if (asprintf(&fname, "%s/.config/firejail", cfg.homedir) == -1)
errExit("asprintf");
if (stat(fname, &s) == 0)
disable_file(BLACKLIST_FILE, fname);
free(fname);
// disable run time information
if (stat(RUN_FIREJAIL_NETWORK_DIR, &s) == 0)
disable_file(BLACKLIST_FILE, RUN_FIREJAIL_NETWORK_DIR);
if (stat(RUN_FIREJAIL_BANDWIDTH_DIR, &s) == 0)
disable_file(BLACKLIST_FILE, RUN_FIREJAIL_BANDWIDTH_DIR);
if (stat(RUN_FIREJAIL_NAME_DIR, &s) == 0)
disable_file(BLACKLIST_FILE, RUN_FIREJAIL_NAME_DIR);
if (stat(RUN_FIREJAIL_X11_DIR, &s) == 0)
disable_file(BLACKLIST_FILE, RUN_FIREJAIL_X11_DIR);
}
// build a basic read-only filesystem
void fs_basic_fs(void) {
uid_t uid = getuid();
if (arg_debug)
printf("Mounting read-only /bin, /sbin, /lib, /lib32, /lib64, /usr");
if (!arg_writable_etc) {
fs_rdonly("/etc");
if (uid)
fs_noexec("/etc");
if (arg_debug) printf(", /etc");
}
if (!arg_writable_var) {
fs_rdonly("/var");
if (uid)
fs_noexec("/var");
if (arg_debug) printf(", /var");
}
if (arg_debug) printf("\n");
fs_rdonly("/bin");
fs_rdonly("/sbin");
fs_rdonly("/lib");
fs_rdonly("/lib64");
fs_rdonly("/lib32");
fs_rdonly("/libx32");
fs_rdonly("/usr");
// update /var directory in order to support multiple sandboxes running on the same root directory
fs_var_lock();
if (!arg_keep_var_tmp)
fs_var_tmp();
if (!arg_writable_var_log)
fs_var_log();
else
fs_rdwr("/var/log");
fs_var_lib();
fs_var_cache();
fs_var_utmp();
fs_machineid();
// don't leak user information
restrict_users();
// when starting as root, firejail config is not disabled;
if (uid)
disable_config();
}
// this function is called from sandbox.c before blacklist/whitelist functions
void fs_private_tmp(void) {
// check XAUTHORITY file, KDE keeps it under /tmp
char *xauth = getenv("XAUTHORITY");
if (xauth) {
char *rp = realpath(xauth, NULL);
if (rp && strncmp(rp, "/tmp/", 5) == 0) {
char *cmd;
if (asprintf(&cmd, "whitelist %s", rp) == -1)
errExit("asprintf");
profile_add(cmd); // profile_add does not duplicate the string
}
if (rp)
free(rp);
}
// whitelist x11 directory
profile_add("whitelist /tmp/.X11-unix");
// whitelist any pulse* file in /tmp directory
// some distros use PulseAudio sockets under /tmp instead of the socket in /urn/user
DIR *dir;
if (!(dir = opendir("/tmp"))) {
// sleep 2 seconds and try again
sleep(2);
if (!(dir = opendir("/tmp"))) {
return;
}
}
struct dirent *entry;
while ((entry = readdir(dir))) {
if (strncmp(entry->d_name, "pulse-", 6) == 0) {
char *cmd;
if (asprintf(&cmd, "whitelist /tmp/%s", entry->d_name) == -1)
errExit("asprintf");
profile_add(cmd); // profile_add does not duplicate the string
}
}
closedir(dir);
}
// this function is called from sandbox.c before blacklist/whitelist functions
void fs_private_cache(void) {
char *cache;
if (asprintf(&cache, "%s/.cache", cfg.homedir) == -1)
errExit("asprintf");
// check if ~/.cache is a valid destination
struct stat s;
if (is_link(cache)) {
fwarning("user .cache is a symbolic link, tmpfs not mounted\n");
free(cache);
return;
}
if (stat(cache, &s) == -1 || !S_ISDIR(s.st_mode)) {
fwarning("no user .cache directory found, tmpfs not mounted\n");
free(cache);
return;
}
if (s.st_uid != getuid()) {
fwarning("user .cache is not owned by current user, tmpfs not mounted\n");
free(cache);
return;
}
if (arg_debug)
printf("Mounting tmpfs on %s\n", cache);
// get a file descriptor for ~/.cache, fails if there is any symlink
int fd = safe_fd(cache, O_PATH|O_DIRECTORY|O_NOFOLLOW|O_CLOEXEC);
if (fd == -1)
errExit("safe_fd");
// confirm that actual mount destination is owned by the user
if (fstat(fd, &s) == -1 || s.st_uid != getuid())
errExit("fstat");
// mount a tmpfs on ~/.cache via the symbolic link in /proc/self/fd
char *proc;
if (asprintf(&proc, "/proc/self/fd/%d", fd) == -1)
errExit("asprintf");
if (mount("tmpfs", proc, "tmpfs", MS_NOSUID | MS_NODEV | MS_STRICTATIME | MS_REC, 0) < 0)
errExit("mounting tmpfs");
fs_logger2("tmpfs", cache);
free(proc);
close(fd);
// check the last mount operation
MountData *mdata = get_last_mount();
assert(mdata);
if (strcmp(mdata->fstype, "tmpfs") != 0 || strcmp(mdata->dir, cache) != 0)
errLogExit("invalid .cache mount");
// get a new file descriptor for ~/.cache, the old directory is masked by the tmpfs
fd = safe_fd(cache, O_RDONLY|O_DIRECTORY|O_NOFOLLOW|O_CLOEXEC);
if (fd == -1)
errExit("safe_fd");
free(cache);
// restore permissions
SET_PERMS_FD(fd, s.st_uid, s.st_gid, s.st_mode);
close(fd);
}
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