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|
/*
* Copyright (C) 2014-2019 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.
*/
#define _XOPEN_SOURCE 500
#include "firejail.h"
#include <ftw.h>
#include <sys/stat.h>
#include <sys/mount.h>
#include <syslog.h>
#include <errno.h>
#include <dirent.h>
#include <grp.h>
#include <sys/ioctl.h>
#include <termios.h>
#include <sys/wait.h>
#include <fcntl.h>
#ifndef O_PATH
# define O_PATH 010000000
#endif
#define MAX_GROUPS 1024
#define MAXBUF 4098
#define EMPTY_STRING ("")
// send the error to /var/log/auth.log and exit after a small delay
void errLogExit(char* fmt, ...) {
va_list args;
va_start(args,fmt);
openlog("firejail", LOG_NDELAY | LOG_PID, LOG_AUTH);
MountData *m = get_last_mount();
char *msg1;
char *msg2 = "Access error";
if (vasprintf(&msg1, fmt, args) != -1 &&
asprintf(&msg2, "Access error: uid %d, last mount name:%s dir:%s type:%s - %s", getuid(), m->fsname, m->dir, m->fstype, msg1) != -1)
syslog(LOG_CRIT, "%s", msg2);
va_end(args);
closelog();
sleep(2);
fprintf(stderr, "%s\n", msg2);
exit(1);
}
static void clean_supplementary_groups(gid_t gid) {
assert(cfg.username);
gid_t groups[MAX_GROUPS];
int ngroups = MAX_GROUPS;
int rv = getgrouplist(cfg.username, gid, groups, &ngroups);
if (rv == -1)
goto clean_all;
// clean supplementary group list
// allow only tty, audio, video, games
gid_t new_groups[MAX_GROUPS];
int new_ngroups = 0;
char *allowed[] = {
"tty",
"audio",
"video",
"games",
NULL
};
int i = 0;
while (allowed[i]) {
gid_t g = get_group_id(allowed[i]);
if (g) {
int j;
for (j = 0; j < ngroups; j++) {
if (g == groups[j]) {
new_groups[new_ngroups] = g;
new_ngroups++;
break;
}
}
}
i++;
}
if (new_ngroups) {
rv = setgroups(new_ngroups, new_groups);
if (rv)
goto clean_all;
if (arg_debug) {
printf("Supplementary groups: ");
for (i = 0; i < new_ngroups; i++)
printf("%d ", new_groups[i]);
printf("\n");
}
}
else
goto clean_all;
return;
clean_all:
fwarning("cleaning all supplementary groups\n");
if (setgroups(0, NULL) < 0)
errExit("setgroups");
}
// drop privileges
// - for root group or if nogroups is set, supplementary groups are not configured
void drop_privs(int nogroups) {
gid_t gid = getgid();
if (arg_debug)
printf("Drop privileges: pid %d, uid %d, gid %d, nogroups %d\n", getpid(), getuid(), gid, nogroups);
// configure supplementary groups
EUID_ROOT();
if (gid == 0 || nogroups) {
if (setgroups(0, NULL) < 0)
errExit("setgroups");
if (arg_debug)
printf("No supplementary groups\n");
}
else if (arg_noroot)
clean_supplementary_groups(gid);
// set uid/gid
if (setresgid(-1, getgid(), getgid()) != 0)
errExit("setresgid");
if (setresuid(-1, getuid(), getuid()) != 0)
errExit("setresuid");
}
int mkpath_as_root(const char* path) {
assert(path && *path);
// work on a copy of the path
char *file_path = strdup(path);
if (!file_path)
errExit("strdup");
char* p;
int done = 0;
for (p=strchr(file_path+1, '/'); p; p=strchr(p+1, '/')) {
*p='\0';
if (mkdir(file_path, 0755)==-1) {
if (errno != EEXIST) {
free(file_path);
return -1;
}
}
else {
if (set_perms(file_path, 0, 0, 0755))
errExit("set_perms");
done = 1;
}
*p='/';
}
if (done)
fs_logger2("mkpath", path);
free(file_path);
return 0;
}
void fwarning(char* fmt, ...) {
if (arg_quiet)
return;
va_list args;
va_start(args,fmt);
fprintf(stderr, "Warning: ");
vfprintf(stderr, fmt, args);
va_end(args);
}
void fmessage(char* fmt, ...) { // TODO: this function is duplicated in src/fnet/interface.c
if (arg_quiet)
return;
va_list args;
va_start(args,fmt);
vfprintf(stderr, fmt, args);
va_end(args);
fflush(0);
}
void logsignal(int s) {
if (!arg_debug)
return;
openlog("firejail", LOG_NDELAY | LOG_PID, LOG_USER);
syslog(LOG_INFO, "Signal %d caught", s);
closelog();
}
void logmsg(const char *msg) {
if (!arg_debug)
return;
openlog("firejail", LOG_NDELAY | LOG_PID, LOG_USER);
syslog(LOG_INFO, "%s\n", msg);
closelog();
}
void logargs(int argc, char **argv) {
if (!arg_debug)
return;
int i;
int len = 0;
// calculate message length
for (i = 0; i < argc; i++)
len += strlen(argv[i]) + 1; // + ' '
// build message
char msg[len + 1];
char *ptr = msg;
for (i = 0; i < argc; i++) {
sprintf(ptr, "%s ", argv[i]);
ptr += strlen(ptr);
}
// log message
logmsg(msg);
}
void logerr(const char *msg) {
if (!arg_debug)
return;
openlog("firejail", LOG_NDELAY | LOG_PID, LOG_USER);
syslog(LOG_ERR, "%s\n", msg);
closelog();
}
void set_nice(int inc) {
errno = 0;
int rv = nice(inc);
(void) rv;
if (errno)
fwarning("cannot set nice value\n");
}
static int copy_file_by_fd(int src, int dst) {
assert(src >= 0);
assert(dst >= 0);
ssize_t len;
static const int BUFLEN = 1024;
unsigned char buf[BUFLEN];
while ((len = read(src, buf, BUFLEN)) > 0) {
int done = 0;
while (done != len) {
int rv = write(dst, buf + done, len - done);
if (rv == -1)
return -1;
done += rv;
}
}
// fflush(0);
return 0;
}
// return -1 if error, 0 if no error; if destname already exists, return error
int copy_file(const char *srcname, const char *destname, uid_t uid, gid_t gid, mode_t mode) {
assert(srcname);
assert(destname);
// open source
int src = open(srcname, O_RDONLY);
if (src < 0) {
fwarning("cannot open source file %s, file not copied\n", srcname);
return -1;
}
// open destination
int dst = open(destname, O_CREAT|O_WRONLY|O_TRUNC, S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH);
if (dst < 0) {
fwarning("cannot open destination file %s, file not copied\n", destname);
close(src);
return -1;
}
int errors = copy_file_by_fd(src, dst);
if (!errors) {
if (fchown(dst, uid, gid) == -1)
errExit("fchown");
if (fchmod(dst, mode) == -1)
errExit("fchmod");
}
close(src);
close(dst);
return errors;
}
// return -1 if error, 0 if no error
void copy_file_as_user(const char *srcname, const char *destname, uid_t uid, gid_t gid, mode_t mode) {
pid_t child = fork();
if (child < 0)
errExit("fork");
if (child == 0) {
// drop privileges
drop_privs(0);
// copy, set permissions and ownership
int rv = copy_file(srcname, destname, uid, gid, mode); // already a regular user
if (rv)
fwarning("cannot copy %s\n", srcname);
#ifdef HAVE_GCOV
__gcov_flush();
#endif
_exit(0);
}
// wait for the child to finish
waitpid(child, NULL, 0);
}
void copy_file_from_user_to_root(const char *srcname, const char *destname, uid_t uid, gid_t gid, mode_t mode) {
// open destination
int dst = open(destname, O_CREAT|O_WRONLY|O_TRUNC, S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH);
if (dst < 0) {
fwarning("cannot open destination file %s, file not copied\n", destname);
return;
}
pid_t child = fork();
if (child < 0)
errExit("fork");
if (child == 0) {
// drop privileges
drop_privs(0);
int src = open(srcname, O_RDONLY);
if (src < 0) {
fwarning("cannot open source file %s, file not copied\n", srcname);
} else {
if (copy_file_by_fd(src, dst)) {
fwarning("cannot copy %s\n", srcname);
}
close(src);
}
close(dst);
#ifdef HAVE_GCOV
__gcov_flush();
#endif
_exit(0);
}
// wait for the child to finish
waitpid(child, NULL, 0);
if (fchown(dst, uid, gid) == -1)
errExit("fchown");
if (fchmod(dst, mode) == -1)
errExit("fchmod");
close(dst);
}
// return -1 if error, 0 if no error
void touch_file_as_user(const char *fname, mode_t mode) {
pid_t child = fork();
if (child < 0)
errExit("fork");
if (child == 0) {
// drop privileges
drop_privs(0);
FILE *fp = fopen(fname, "wx");
if (fp) {
fprintf(fp, "\n");
SET_PERMS_STREAM(fp, -1, -1, mode);
fclose(fp);
}
#ifdef HAVE_GCOV
__gcov_flush();
#endif
_exit(0);
}
// wait for the child to finish
waitpid(child, NULL, 0);
}
// return 1 if the file is a directory
int is_dir(const char *fname) {
assert(fname);
if (*fname == '\0')
return 0;
// if fname doesn't end in '/', add one
int rv;
struct stat s;
if (fname[strlen(fname) - 1] == '/')
rv = stat(fname, &s);
else {
char *tmp;
if (asprintf(&tmp, "%s/", fname) == -1) {
fprintf(stderr, "Error: cannot allocate memory, %s:%d\n", __FILE__, __LINE__);
errExit("asprintf");
}
rv = stat(tmp, &s);
free(tmp);
}
if (rv == -1)
return 0;
if (S_ISDIR(s.st_mode))
return 1;
return 0;
}
// return 1 if the file is a link
int is_link(const char *fname) {
assert(fname);
if (*fname == '\0')
return 0;
char *dup = NULL;
struct stat s;
if (lstat(fname, &s) == 0) {
if (S_ISLNK(s.st_mode))
return 1;
if (S_ISDIR(s.st_mode)) {
// remove trailing slashes and single dots and try again
dup = strdup(fname);
if (!dup)
errExit("strdup");
trim_trailing_slash_or_dot(dup);
if (lstat(dup, &s) == 0) {
if (S_ISLNK(s.st_mode)) {
free(dup);
return 1;
}
}
}
}
free(dup);
return 0;
}
// remove all slashes and single dots from the end of a path
// for example /foo/bar///././. -> /foo/bar
void trim_trailing_slash_or_dot(char *path) {
assert(path);
char *end = strchr(path, '\0');
if ((end - path) > 1) {
end--;
while (*end == '/' ||
(*end == '.' && *(end - 1) == '/')) {
*end = '\0';
end--;
if (end == path)
break;
}
}
}
// remove multiple spaces and return allocated memory
char *line_remove_spaces(const char *buf) {
EUID_ASSERT();
assert(buf);
size_t len = strlen(buf);
if (len == 0)
return NULL;
// allocate memory for the new string
char *rv = malloc(len + 1);
if (rv == NULL)
errExit("malloc");
// remove space at start of line
const char *ptr1 = buf;
while (*ptr1 == ' ' || *ptr1 == '\t')
ptr1++;
// copy data and remove additional spaces
char *ptr2 = rv;
int state = 0;
while (*ptr1 != '\0') {
if (*ptr1 == '\n' || *ptr1 == '\r')
break;
if (state == 0) {
if (*ptr1 != ' ' && *ptr1 != '\t')
*ptr2++ = *ptr1++;
else {
*ptr2++ = ' ';
ptr1++;
state = 1;
}
}
else { // state == 1
while (*ptr1 == ' ' || *ptr1 == '\t')
ptr1++;
state = 0;
}
}
// strip last blank character if any
if (ptr2 > rv && *(ptr2 - 1) == ' ')
--ptr2;
*ptr2 = '\0';
// if (arg_debug)
// printf("Processing line #%s#\n", rv);
return rv;
}
char *split_comma(char *str) {
EUID_ASSERT();
if (str == NULL || *str == '\0')
return NULL;
char *ptr = strchr(str, ',');
if (!ptr)
return NULL;
*ptr = '\0';
ptr++;
if (*ptr == '\0')
return NULL;
return ptr;
}
// remove consecutive and trailing slashes
// and return allocated memory
// e.g. /home//user/ -> /home/user
char *clean_pathname(const char *path) {
assert(path);
size_t len = strlen(path);
char *rv = malloc(len + 1);
if (!rv)
errExit("malloc");
if (len > 0) {
size_t i = 0, j = 0, cnt = 0;
for (; i < len; i++) {
if (path[i] == '/')
cnt++;
else
cnt = 0;
if (cnt < 2) {
rv[j] = path[i];
j++;
}
}
rv[j] = '\0';
// remove a trailing slash
if (j > 1 && rv[j - 1] == '/')
rv[j - 1] = '\0';
}
else
*rv = '\0';
return rv;
}
void check_unsigned(const char *str, const char *msg) {
EUID_ASSERT();
const char *ptr = str;
while (*ptr != ' ' && *ptr != '\t' && *ptr != '\0') {
if (!isdigit(*ptr)) {
fprintf(stderr, "%s %s\n", msg, str);
exit(1);
}
ptr++;
}
}
#define BUFLEN 4096
// find the first child for this parent; return 1 if error
int find_child(pid_t parent, pid_t *child) {
EUID_ASSERT();
*child = 0; // use it to flag a found child
DIR *dir;
EUID_ROOT(); // grsecurity fix
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);
}
}
struct dirent *entry;
char *end;
while (*child == 0 && (entry = readdir(dir))) {
pid_t pid = strtol(entry->d_name, &end, 10);
if (end == entry->d_name || *end)
continue;
if (pid == parent)
continue;
// open stat file
char *file;
if (asprintf(&file, "/proc/%u/status", pid) == -1) {
perror("asprintf");
exit(1);
}
FILE *fp = fopen(file, "r");
if (!fp) {
free(file);
continue;
}
// look for firejail executable name
char buf[BUFLEN];
while (fgets(buf, BUFLEN - 1, fp)) {
if (strncmp(buf, "PPid:", 5) == 0) {
char *ptr = buf + 5;
while (*ptr != '\0' && (*ptr == ' ' || *ptr == '\t')) {
ptr++;
}
if (*ptr == '\0') {
fprintf(stderr, "Error: cannot read /proc file\n");
exit(1);
}
if (parent == atoi(ptr))
*child = pid;
break; // stop reading the file
}
}
fclose(fp);
free(file);
}
closedir(dir);
EUID_USER();
return (*child)? 0:1; // 0 = found, 1 = not found
}
void extract_command_name(int index, char **argv) {
EUID_ASSERT();
assert(argv);
assert(argv[index]);
// configure command index
cfg.original_program_index = index;
char *str = strdup(argv[index]);
if (!str)
errExit("strdup");
// if we have a symbolic link, use the real path to extract the name
// if (is_link(argv[index])) {
// char*newname = realpath(argv[index], NULL);
// if (newname) {
// free(str);
// str = newname;
// }
// }
// configure command name
cfg.command_name = str;
if (!cfg.command_name)
errExit("strdup");
// remove the path: /usr/bin/firefox becomes firefox
char *basename = cfg.command_name;
char *ptr = strrchr(cfg.command_name, '/');
if (ptr) {
basename = ++ptr;
if (*ptr == '\0') {
fprintf(stderr, "Error: invalid command name\n");
exit(1);
}
}
else
ptr = basename;
// restrict the command name to the first word
while (*ptr != ' ' && *ptr != '\t' && *ptr != '\0')
ptr++;
// command name is a substring of cfg.command_name
if (basename != cfg.command_name || *ptr != '\0') {
*ptr = '\0';
basename = strdup(basename);
if (!basename)
errExit("strdup");
free(cfg.command_name);
cfg.command_name = basename;
}
}
void update_map(char *mapping, char *map_file) {
int fd;
size_t j;
size_t map_len; /* Length of 'mapping' */
/* Replace commas in mapping string with newlines */
map_len = strlen(mapping);
for (j = 0; j < map_len; j++)
if (mapping[j] == ',')
mapping[j] = '\n';
fd = open(map_file, O_RDWR);
if (fd == -1) {
fprintf(stderr, "Error: cannot open %s: %s\n", map_file, strerror(errno));
exit(EXIT_FAILURE);
}
if (write(fd, mapping, map_len) != (ssize_t)map_len) {
fprintf(stderr, "Error: cannot write to %s: %s\n", map_file, strerror(errno));
exit(EXIT_FAILURE);
}
close(fd);
}
void wait_for_other(int fd) {
//****************************
// wait for the parent to be initialized
//****************************
char childstr[BUFLEN + 1];
int newfd = dup(fd);
if (newfd == -1)
errExit("dup");
FILE* stream;
stream = fdopen(newfd, "r");
*childstr = '\0';
if (fgets(childstr, BUFLEN, stream)) {
// remove \n)
char *ptr = childstr;
while(*ptr !='\0' && *ptr != '\n')
ptr++;
if (*ptr == '\0')
errExit("fgets");
*ptr = '\0';
}
else {
fprintf(stderr, "Error: proc %d cannot sync with peer: %s\n",
getpid(), ferror(stream) ? strerror(errno) : "unexpected EOF");
int status = 0;
pid_t pid = wait(&status);
if (pid != -1) {
if (WIFEXITED(status))
fprintf(stderr, "Peer %d unexpectedly exited with status %d\n",
pid, WEXITSTATUS(status));
else if (WIFSIGNALED(status))
fprintf(stderr, "Peer %d unexpectedly killed (%s)\n",
pid, strsignal(WTERMSIG(status)));
else
fprintf(stderr, "Peer %d unexpectedly exited "
"(un-decodable wait status %04x)\n", pid, status);
}
exit(1);
}
if (strcmp(childstr, "arg_noroot=0") == 0)
arg_noroot = 0;
else if (strcmp(childstr, "arg_noroot=1") == 0)
arg_noroot = 1;
else {
fprintf(stderr, "Error: unexpected message from peer: %s\n", childstr);
exit(1);
}
fclose(stream);
}
void notify_other(int fd) {
FILE* stream;
int newfd = dup(fd);
if (newfd == -1)
errExit("dup");
stream = fdopen(newfd, "w");
fprintf(stream, "arg_noroot=%d\n", arg_noroot);
fflush(stream);
fclose(stream);
}
// Equivalent to the GNU version of basename, which is incompatible with
// the POSIX basename. A few lines of code saves any portability pain.
// https://www.gnu.org/software/libc/manual/html_node/Finding-Tokens-in-a-String.html#index-basename
const char *gnu_basename(const char *path) {
const char *last_slash = strrchr(path, '/');
if (!last_slash)
return path;
return last_slash+1;
}
uid_t pid_get_uid(pid_t pid) {
EUID_ASSERT();
uid_t rv = 0;
// open status file
char *file;
if (asprintf(&file, "/proc/%u/status", pid) == -1) {
perror("asprintf");
exit(1);
}
EUID_ROOT(); // grsecurity fix
FILE *fp = fopen(file, "r");
if (!fp) {
free(file);
fprintf(stderr, "Error: cannot open /proc file\n");
exit(1);
}
// extract uid
static const int PIDS_BUFLEN = 1024;
char buf[PIDS_BUFLEN];
while (fgets(buf, PIDS_BUFLEN - 1, fp)) {
if (strncmp(buf, "Uid:", 4) == 0) {
char *ptr = buf + 4;
while (*ptr != '\0' && (*ptr == ' ' || *ptr == '\t')) {
ptr++;
}
if (*ptr == '\0') {
fprintf(stderr, "Error: cannot read /proc file\n");
exit(1);
}
rv = atoi(ptr);
break; // break regardless!
}
}
fclose(fp);
free(file);
EUID_USER(); // grsecurity fix
return rv;
}
uid_t get_group_id(const char *group) {
// find tty group id
gid_t gid = 0;
struct group *g = getgrnam(group);
if (g)
gid = g->gr_gid;
return gid;
}
static int remove_callback(const char *fpath, const struct stat *sb, int typeflag, struct FTW *ftwbuf) {
(void) sb;
(void) typeflag;
(void) ftwbuf;
assert(fpath);
if (strcmp(fpath, ".") == 0)
return 0;
if (remove(fpath)) { // removes the link not the actual file
perror("remove");
fprintf(stderr, "Error: cannot remove file from user .firejail directory: %s\n", fpath);
exit(1);
}
return 0;
}
int remove_overlay_directory(void) {
EUID_ASSERT();
struct stat s;
sleep(1);
char *path;
if (asprintf(&path, "%s/.firejail", cfg.homedir) == -1)
errExit("asprintf");
if (lstat(path, &s) == 0) {
// deal with obvious problems such as symlinks and root ownership
if (!S_ISDIR(s.st_mode)) {
if (S_ISLNK(s.st_mode))
fprintf(stderr, "Error: %s is a symbolic link\n", path);
else
fprintf(stderr, "Error: %s is not a directory\n", path);
exit(1);
}
if (s.st_uid != getuid()) {
fprintf(stderr, "Error: %s is not owned by the current user\n", path);
exit(1);
}
pid_t child = fork();
if (child < 0)
errExit("fork");
if (child == 0) {
// open ~/.firejail, fails if there is any symlink
int fd = safe_fd(path, O_PATH|O_DIRECTORY|O_NOFOLLOW|O_CLOEXEC);
if (fd == -1)
errExit("safe_fd");
// chdir to ~/.firejail
if (fchdir(fd) == -1)
errExit("fchdir");
close(fd);
EUID_ROOT();
// FTW_PHYS - do not follow symbolic links
if (nftw(".", remove_callback, 64, FTW_DEPTH | FTW_PHYS) == -1)
errExit("nftw");
EUID_USER();
// remove ~/.firejail
if (rmdir(path) == -1)
errExit("rmdir");
#ifdef HAVE_GCOV
__gcov_flush();
#endif
_exit(0);
}
// wait for the child to finish
waitpid(child, NULL, 0);
// check if ~/.firejail was deleted
if (stat(path, &s) == 0)
return 1;
}
return 0;
}
void flush_stdin(void) {
if (isatty(STDIN_FILENO)) {
int cnt = 0;
int rv = ioctl(STDIN_FILENO, FIONREAD, &cnt);
if (rv == 0 && cnt) {
fwarning("removing %d bytes from stdin\n", cnt);
rv = ioctl(STDIN_FILENO, TCFLSH, TCIFLUSH);
(void) rv;
}
}
}
// return 1 if new directory was created, else return 0
int create_empty_dir_as_user(const char *dir, mode_t mode) {
assert(dir);
mode &= 07777;
struct stat s;
if (stat(dir, &s)) {
if (arg_debug)
printf("Creating empty %s directory\n", dir);
pid_t child = fork();
if (child < 0)
errExit("fork");
if (child == 0) {
// drop privileges
drop_privs(0);
if (mkdir(dir, mode) == 0) {
if (chmod(dir, mode) == -1)
{;} // do nothing
}
else if (arg_debug) {
char *str;
if (asprintf(&str, "Directory %s not created", dir) == -1)
errExit("asprintf");
perror(str);
}
#ifdef HAVE_GCOV
__gcov_flush();
#endif
_exit(0);
}
waitpid(child, NULL, 0);
if (stat(dir, &s) == 0)
return 1;
}
return 0;
}
void create_empty_dir_as_root(const char *dir, mode_t mode) {
assert(dir);
mode &= 07777;
struct stat s;
if (stat(dir, &s)) {
if (arg_debug)
printf("Creating empty %s directory\n", dir);
/* coverity[toctou] */
// don't fail if directory already exists. This can be the case in a race
// condition, when two jails launch at the same time. See #1013
if (mkdir(dir, mode) == -1 && errno != EEXIST)
errExit("mkdir");
if (set_perms(dir, 0, 0, mode))
errExit("set_perms");
ASSERT_PERMS(dir, 0, 0, mode);
}
}
void create_empty_file_as_root(const char *fname, mode_t mode) {
assert(fname);
mode &= 07777;
struct stat s;
if (stat(fname, &s)) {
if (arg_debug)
printf("Creating empty %s file\n", fname);
/* coverity[toctou] */
FILE *fp = fopen(fname, "w");
if (!fp)
errExit("fopen");
SET_PERMS_STREAM(fp, 0, 0, mode);
fclose(fp);
}
}
// return 1 if error
int set_perms(const char *fname, uid_t uid, gid_t gid, mode_t mode) {
assert(fname);
if (chmod(fname, mode) == -1)
return 1;
if (chown(fname, uid, gid) == -1)
return 1;
return 0;
}
void mkdir_attr(const char *fname, mode_t mode, uid_t uid, gid_t gid) {
assert(fname);
mode &= 07777;
#if 0
printf("fname %s, uid %d, gid %d, mode %x - ", fname, uid, gid, (unsigned) mode);
if (S_ISLNK(mode))
printf("l");
else if (S_ISDIR(mode))
printf("d");
else if (S_ISCHR(mode))
printf("c");
else if (S_ISBLK(mode))
printf("b");
else if (S_ISSOCK(mode))
printf("s");
else
printf("-");
printf( (mode & S_IRUSR) ? "r" : "-");
printf( (mode & S_IWUSR) ? "w" : "-");
printf( (mode & S_IXUSR) ? "x" : "-");
printf( (mode & S_IRGRP) ? "r" : "-");
printf( (mode & S_IWGRP) ? "w" : "-");
printf( (mode & S_IXGRP) ? "x" : "-");
printf( (mode & S_IROTH) ? "r" : "-");
printf( (mode & S_IWOTH) ? "w" : "-");
printf( (mode & S_IXOTH) ? "x" : "-");
printf("\n");
#endif
if (mkdir(fname, mode) == -1 ||
chmod(fname, mode) == -1 ||
chown(fname, uid, gid)) {
fprintf(stderr, "Error: failed to create %s directory\n", fname);
errExit("mkdir/chmod");
}
ASSERT_PERMS(fname, uid, gid, mode);
}
unsigned extract_timeout(const char *str) {
unsigned s;
unsigned m;
unsigned h;
int rv = sscanf(str, "%02u:%02u:%02u", &h, &m, &s);
if (rv != 3) {
fprintf(stderr, "Error: invalid timeout, please use a hh:mm:ss format\n");
exit(1);
}
unsigned timeout = h * 3600 + m * 60 + s;
if (timeout == 0) {
fprintf(stderr, "Error: invalid timeout\n");
exit(1);
}
return timeout;
}
void disable_file_or_dir(const char *fname) {
if (arg_debug)
printf("blacklist %s\n", fname);
struct stat s;
if (stat(fname, &s) != -1) {
if (is_dir(fname)) {
if (mount(RUN_RO_DIR, fname, "none", MS_BIND, "mode=400,gid=0") < 0)
errExit("disable directory");
}
else {
if (mount(RUN_RO_FILE, fname, "none", MS_BIND, "mode=400,gid=0") < 0)
errExit("disable file");
}
}
fs_logger2("blacklist", fname);
}
void disable_file_path(const char *path, const char *file) {
assert(file);
assert(path);
char *fname;
if (asprintf(&fname, "%s/%s", path, file) == -1)
errExit("asprintf");
disable_file_or_dir(fname);
free(fname);
}
// open file without following any symbolic link
// returns a file descriptor on success, or -1 if a symlink is found
int safe_fd(const char *path, int flags) {
assert(path);
if (*path != '/')
goto errexit;
if (strstr(path, ".."))
goto errexit;
int parentfd = open("/", O_PATH|O_DIRECTORY|O_CLOEXEC);
if (parentfd == -1)
errExit("open");
int fd = -1;
char *last_tok = EMPTY_STRING;
char *dup = strdup(path);
if (!dup)
errExit("strdup");
char *tok = strtok(dup, "/");
if (!tok) { // root directory
free(dup);
return parentfd;
}
while (tok) {
// open the element, assuming it is a directory; this fails with ENOTDIR if it is a symbolic link
// if token is a single dot, the previous directory is reopened
fd = openat(parentfd, tok, O_PATH|O_DIRECTORY|O_NOFOLLOW|O_CLOEXEC);
if (fd == -1) {
// if the following token is NULL, the current token is the final path element
// try again to open it, this time using the passed flags, and return -1 or the descriptor
last_tok = tok;
tok = strtok(NULL, "/");
if (!tok)
fd = openat(parentfd, last_tok, flags|O_NOFOLLOW);
close(parentfd);
free(dup);
return fd; // -1 if open failed
}
// move on to next path segment
last_tok = tok;
tok = strtok(NULL, "/");
if (tok) {
close(parentfd);
parentfd = fd;
}
}
// we are here because the last path element exists and is of file type directory
// reopen it using the passed flags
close(fd);
fd = openat(parentfd, last_tok, flags|O_NOFOLLOW);
close(parentfd);
free(dup);
return fd; // -1 if open failed
errexit:
fprintf(stderr, "Error: cannot open \"%s\": invalid path\n", path);
exit(1);
}
// return 1 if the sandbox identified by pid is not fully set up yet or if
// it is no firejail sandbox at all, return 0 if the sandbox is complete
int invalid_sandbox(const pid_t pid) {
// check if a file "ready-for-join" exists
char *fname;
if (asprintf(&fname, "/proc/%d/root%s", pid, RUN_READY_FOR_JOIN) == -1)
errExit("asprintf");
EUID_ROOT();
FILE *fp = fopen(fname, "re");
EUID_USER();
free(fname);
if (!fp)
return 1;
// regular file owned by root
int fd = fileno(fp);
if (fd == -1)
errExit("fileno");
struct stat s;
if (fstat(fd, &s) == -1)
errExit("fstat");
if (!S_ISREG(s.st_mode) || s.st_uid != 0) {
fclose(fp);
return 1;
}
// check if it is non-empty
char buf[BUFLEN];
if (fgets(buf, BUFLEN, fp) == NULL) {
fclose(fp);
return 1;
}
fclose(fp);
// confirm "ready" string was written
if (strncmp(buf, "ready\n", 6) != 0)
return 1;
// walk down the process tree a few nodes, there should be no firejail leaf
#define MAXNODES 5
pid_t current = pid, next;
int i;
for (i = 0; i < MAXNODES; i++) {
if (find_child(current, &next) == 1) {
// found a leaf
EUID_ROOT();
char *comm = pid_proc_comm(current);
EUID_USER();
if (!comm) {
fprintf(stderr, "Error: cannot read /proc file\n");
exit(1);
}
if (strcmp(comm, "firejail") == 0) {
free(comm);
return 1;
}
free(comm);
break;
}
current = next;
}
return 0;
}
int has_handler(pid_t pid, int signal) {
if (signal > 0 && signal <= SIGRTMAX) {
char *fname;
if (asprintf(&fname, "/proc/%d/status", pid) == -1)
errExit("asprintf");
EUID_ROOT();
FILE *fp = fopen(fname, "re");
EUID_USER();
free(fname);
if (fp) {
char buf[BUFLEN];
while (fgets(buf, BUFLEN, fp)) {
if (strncmp(buf, "SigCgt:", 7) == 0) {
unsigned long long val;
if (sscanf(buf + 7, "%llx", &val) != 1) {
fprintf(stderr, "Error: cannot read /proc file\n");
exit(1);
}
val >>= (signal - 1);
val &= 1ULL;
fclose(fp);
return val; // 1 if process has a handler for the signal, else 0
}
}
fclose(fp);
}
}
return 0;
}
void enter_network_namespace(pid_t pid) {
// in case the pid is that of a firejail process, use the pid of the first child process
pid_t child = switch_to_child(pid);
// now check if the pid belongs to a firejail sandbox
if (invalid_sandbox(child)) {
fprintf(stderr, "Error: no valid sandbox\n");
exit(1);
}
// check privileges for non-root users
uid_t uid = getuid();
if (uid != 0) {
uid_t sandbox_uid = pid_get_uid(pid);
if (uid != sandbox_uid) {
fprintf(stderr, "Error: permission is denied to join a sandbox created by a different user.\n");
exit(1);
}
}
// check network namespace
char *name;
if (asprintf(&name, "/run/firejail/network/%d-netmap", pid) == -1)
errExit("asprintf");
struct stat s;
if (stat(name, &s) == -1) {
fprintf(stderr, "Error: the sandbox doesn't use a new network namespace\n");
exit(1);
}
// join the namespace
EUID_ROOT();
if (join_namespace(child, "net")) {
fprintf(stderr, "Error: cannot join the network namespace\n");
exit(1);
}
}
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