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|
/*
* Copyright (C) 2014-2016 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 <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>
#include <ftw.h>
static void skel(const char *homedir, uid_t u, gid_t g) {
char *fname;
// zsh
if (!arg_shell_none && (strcmp(cfg.shell,"/usr/bin/zsh") == 0 || strcmp(cfg.shell,"/bin/zsh") == 0)) {
// 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, u, g, 0644) == 0) {
fs_logger("clone /etc/skel/.zshrc");
}
}
else { //
FILE *fp = fopen(fname, "w");
if (fp) {
fprintf(fp, "\n");
SET_PERMS_STREAM(fp, u, g, S_IRUSR | S_IWUSR);
fclose(fp);
fs_logger2("touch", fname);
}
}
free(fname);
}
// csh
else if (!arg_shell_none && strcmp(cfg.shell,"/bin/csh") == 0) {
// 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, u, g, 0644) == 0) {
fs_logger("clone /etc/skel/.cshrc");
}
}
else { //
/* coverity[toctou] */
FILE *fp = fopen(fname, "w");
if (fp) {
fprintf(fp, "\n");
SET_PERMS_STREAM(fp, u, g, S_IRUSR | S_IWUSR);
fclose(fp);
fs_logger2("touch", fname);
}
}
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, u, g, 0644) == 0) {
fs_logger("clone /etc/skel/.bashrc");
}
}
free(fname);
}
}
static int store_xauthority(void) {
// put a copy of .Xauthority in XAUTHORITY_FILE
fs_build_mnt_dir();
char *src;
char *dest = RUN_XAUTHORITY_FILE;
if (asprintf(&src, "%s/.Xauthority", cfg.homedir) == -1)
errExit("asprintf");
struct stat s;
if (stat(src, &s) == 0) {
if (is_link(src)) {
fprintf(stderr, "Error: invalid .Xauthority file\n");
exit(1);
}
int rv = copy_file(src, dest, -1, -1, 0600);
if (rv) {
fprintf(stderr, "Warning: cannot transfer .Xauthority in private home directory\n");
return 0;
}
return 1; // file copied
}
return 0;
}
static int store_asoundrc(void) {
// put a copy of .Xauthority in XAUTHORITY_FILE
fs_build_mnt_dir();
char *src;
char *dest = RUN_ASOUNDRC_FILE;
if (asprintf(&src, "%s/.asoundrc", cfg.homedir) == -1)
errExit("asprintf");
struct stat s;
if (stat(src, &s) == 0) {
if (is_link(src)) {
// make sure the real path of the file is inside the home directory
char* rp = realpath(src, NULL);
if (!rp) {
fprintf(stderr, "Error: Cannot access %s\n", src);
exit(1);
}
if (strncmp(rp, cfg.homedir, strlen(cfg.homedir)) != 0) {
fprintf(stderr, "Error: .asoundrc is a symbolic link pointing to a file outside home directory\n");
exit(1);
}
free(rp);
}
int rv = copy_file(src, dest, -1, -1, -0644);
if (rv) {
fprintf(stderr, "Warning: cannot transfer .asoundrc in private home directory\n");
return 0;
}
return 1; // file copied
}
return 0;
}
static void copy_xauthority(void) {
// copy XAUTHORITY_FILE in the new home directory
char *src = RUN_XAUTHORITY_FILE ;
char *dest;
if (asprintf(&dest, "%s/.Xauthority", cfg.homedir) == -1)
errExit("asprintf");
// copy, set permissions and ownership
int rv = copy_file(src, dest, getuid(), getgid(), S_IRUSR | S_IWUSR);
if (rv)
fprintf(stderr, "Warning: cannot transfer .Xauthority in private home directory\n");
else {
fs_logger2("clone", dest);
}
// delete the temporary file
unlink(src);
}
static void copy_asoundrc(void) {
// copy XAUTHORITY_FILE in the new home directory
char *src = RUN_ASOUNDRC_FILE ;
char *dest;
if (asprintf(&dest, "%s/.asoundrc", cfg.homedir) == -1)
errExit("asprintf");
// copy, set permissions and ownership
int rv = copy_file(src, dest, getuid(), getgid(), S_IRUSR | S_IWUSR);
if (rv)
fprintf(stderr, "Warning: cannot transfer .asoundrc in private home directory\n");
else {
fs_logger2("clone", dest);
}
// 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,
// 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();
int aflag = store_asoundrc();
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_NOSUID | MS_NODEV | MS_BIND | MS_REC, NULL) < 0)
errExit("mount bind");
fs_logger3("mount-bind", private_homedir, cfg.homedir);
fs_logger2("whitelist", cfg.homedir);
// 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_NOEXEC | MS_STRICTATIME | MS_REC, "mode=700,gid=0") < 0)
errExit("mounting home directory");
fs_logger("tmpfs /root");
}
else {
// mask /home
if (arg_debug)
printf("Mounting a new /home directory\n");
if (mount("tmpfs", "/home", "tmpfs", MS_NOSUID | MS_NODEV | MS_NOEXEC | MS_STRICTATIME | MS_REC, "mode=755,gid=0") < 0)
errExit("mounting home directory");
fs_logger("tmpfs /home");
}
skel(homedir, u, g);
if (xflag)
copy_xauthority();
if (aflag)
copy_asoundrc();
}
// private mode (--private):
// mount tmpfs over /home/user,
// tmpfs on top of /root in nonroot 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();
int aflag = store_asoundrc();
// mask /home
if (arg_debug)
printf("Mounting a new /home directory\n");
if (mount("tmpfs", "/home", "tmpfs", MS_NOSUID | MS_NODEV | MS_NOEXEC | MS_STRICTATIME | MS_REC, "mode=755,gid=0") < 0)
errExit("mounting home directory");
fs_logger("tmpfs /home");
// mask /root
if (arg_debug)
printf("Mounting a new /root directory\n");
if (mount("tmpfs", "/root", "tmpfs", MS_NOSUID | MS_NODEV | MS_NOEXEC | MS_STRICTATIME | MS_REC, "mode=700,gid=0") < 0)
errExit("mounting root directory");
fs_logger("tmpfs /root");
if (u != 0) {
// create /home/user
if (arg_debug)
printf("Create a new user directory\n");
if (mkdir(homedir, S_IRWXU) == -1) {
if (mkpath_as_root(homedir) == -1)
errExit("mkpath");
if (mkdir(homedir, S_IRWXU) == -1)
errExit("mkdir");
}
if (chown(homedir, u, g) < 0)
errExit("chown");
fs_logger2("mkdir", homedir);
}
skel(homedir, u, g);
if (xflag)
copy_xauthority();
if (aflag)
copy_asoundrc();
}
// check new private home directory (--private= option) - exit if it fails
void fs_check_private_dir(void) {
EUID_ASSERT();
invalid_filename(cfg.home_private);
// Expand the home directory
char *tmp = expand_home(cfg.home_private, cfg.homedir);
cfg.home_private = realpath(tmp, NULL);
free(tmp);
if (!cfg.home_private
|| !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: --private directory should be owned by the current user\n");
exit(1);
}
}
//***********************************************************************************
// --private-home
//***********************************************************************************
#define PRIVATE_COPY_LIMIT (500 * 1024 *1024)
static int size_limit_reached = 0;
static unsigned file_cnt = 0;
static unsigned size_cnt = 0;
static char *check_dir_or_file(const char *name);
int fs_copydir(const char *path, const struct stat *st, int ftype, struct FTW *sftw) {
if (size_limit_reached)
return 0;
struct stat s;
char *dest;
if (asprintf(&dest, "%s%s", RUN_HOME_DIR, path + strlen(cfg.homedir)) == -1)
errExit("asprintf");
// don't copy it if we already have the file
if (stat(dest, &s) == 0) {
free(dest);
return 0;
}
// extract mode and ownership
if (stat(path, &s) != 0) {
free(dest);
return 0;
}
// check uid
if (s.st_uid != firejail_uid || s.st_gid != firejail_gid) {
free(dest);
return 0;
}
if ((s.st_size + size_cnt) > PRIVATE_COPY_LIMIT) {
size_limit_reached = 1;
free(dest);
return 0;
}
file_cnt++;
size_cnt += s.st_size;
if(ftype == FTW_F)
copy_file(path, dest, firejail_uid, firejail_gid, s.st_mode);
else if (ftype == FTW_D) {
if (mkdir(dest, s.st_mode) == -1)
errExit("mkdir");
if (chmod(dest, s.st_mode) < 0) {
fprintf(stderr, "Error: cannot change mode for %s\n", path);
exit(1);
}
if (chown(dest, firejail_uid, firejail_gid) < 0) {
fprintf(stderr, "Error: cannot change ownership for %s\n", path);
exit(1);
}
#if 0
struct stat s2;
if (stat(dest, &s2) == 0) {
printf("%s\t", dest);
printf((S_ISDIR(s.st_mode)) ? "d" : "-");
printf((s.st_mode & S_IRUSR) ? "r" : "-");
printf((s.st_mode & S_IWUSR) ? "w" : "-");
printf((s.st_mode & S_IXUSR) ? "x" : "-");
printf((s.st_mode & S_IRGRP) ? "r" : "-");
printf((s.st_mode & S_IWGRP) ? "w" : "-");
printf((s.st_mode & S_IXGRP) ? "x" : "-");
printf((s.st_mode & S_IROTH) ? "r" : "-");
printf((s.st_mode & S_IWOTH) ? "w" : "-");
printf((s.st_mode & S_IXOTH) ? "x" : "-");
printf("\n");
}
#endif
fs_logger2("clone", path);
}
free(dest);
return(0);
}
static void duplicate(char *name) {
char *fname = check_dir_or_file(name);
if (arg_debug)
printf("Private home: duplicating %s\n", fname);
assert(strncmp(fname, cfg.homedir, strlen(cfg.homedir)) == 0);
struct stat s;
if (stat(fname, &s) == -1) {
free(fname);
return;
}
if(nftw(fname, fs_copydir, 1, FTW_PHYS) != 0) {
fprintf(stderr, "Error: unable to copy template dir\n");
exit(1);
}
fs_logger_print(); // save the current log
free(fname);
}
static char *check_dir_or_file(const char *name) {
assert(name);
struct stat s;
// basic checks
invalid_filename(name);
if (arg_debug)
printf("Private home: checking %s\n", name);
// expand home directory
char *fname = expand_home(name, cfg.homedir);
if (!fname) {
fprintf(stderr, "Error: file %s not found.\n", name);
exit(1);
}
// If it doesn't start with '/', it must be relative to homedir
if (fname[0] != '/') {
char* tmp;
if (asprintf(&tmp, "%s/%s", cfg.homedir, fname) == -1)
errExit("asprintf");
free(fname);
fname = tmp;
}
// check the file is in user home directory
char *rname = realpath(fname, NULL);
if (!rname) {
fprintf(stderr, "Error: invalid file %s\n", name);
exit(1);
}
if (strncmp(rname, cfg.homedir, strlen(cfg.homedir)) != 0) {
fprintf(stderr, "Error: file %s is not in user home directory\n", name);
exit(1);
}
// a full home directory is not allowed
if (strcmp(rname, cfg.homedir) == 0) {
fprintf(stderr, "Error: invalid directory %s\n", rname);
exit(1);
}
// only top files and directories in user home are allowed
char *ptr = rname + strlen(cfg.homedir);
if (*ptr == '\0') {
fprintf(stderr, "Error: invalid file %s\n", name);
exit(1);
}
ptr++;
ptr = strchr(ptr, '/');
if (ptr) {
if (*ptr != '\0') {
fprintf(stderr, "Error: only top files and directories in user home are allowed\n");
exit(1);
}
}
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 rname; // regular exit from the function
}
fprintf(stderr, "Error: invalid file type, %s.\n", fname);
exit(1);
}
// check directory list specified by user (--private-home option) - exit if it fails
void fs_check_home_list(void) {
if (strstr(cfg.home_private_keep, "..")) {
fprintf(stderr, "Error: invalid private-home list\n");
exit(1);
}
char *dlist = strdup(cfg.home_private_keep);
if (!dlist)
errExit("strdup");
char *ptr = strtok(dlist, ",");
char *tmp = check_dir_or_file(ptr);
free(tmp);
while ((ptr = strtok(NULL, ",")) != NULL) {
tmp = check_dir_or_file(ptr);
free(tmp);
}
free(dlist);
}
// private mode (--private-home=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();
int aflag = store_asoundrc();
uid_t u = firejail_uid;
gid_t g = firejail_gid;
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(RUN_HOME_DIR, 0755);
if (rv == -1)
errExit("mkdir");
if (chown(RUN_HOME_DIR, u, g) < 0)
errExit("chown");
if (chmod(RUN_HOME_DIR, 0755) < 0)
errExit("chmod");
ASSERT_PERMS(RUN_HOME_DIR, u, g, 0755);
fs_logger_print(); // save the current log
// 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);
if (!arg_quiet) {
if (size_limit_reached)
fprintf(stderr, "Warning: private-home copy limit of %u MB reached, not all the files were copied\n",
PRIVATE_COPY_LIMIT / (1024 *1024));
else
printf("Private home: %u files, total size %u bytes\n", file_cnt, size_cnt);
}
fs_logger_print(); // save the current log
free(dlist);
exit(0);
}
// wait for the child to finish
waitpid(child, NULL, 0);
if (arg_debug)
printf("Mount-bind %s on top of %s\n", RUN_HOME_DIR, homedir);
if (mount(RUN_HOME_DIR, homedir, NULL, MS_BIND|MS_REC, NULL) < 0)
errExit("mount bind");
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");
}
skel(homedir, u, g);
if (xflag)
copy_xauthority();
if (aflag)
copy_asoundrc();
}
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