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/*
* Copyright (C) 2017 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/types.h>
#include <unistd.h>
#include <dirent.h>
#define MAXBUF 4096
static const char * const lib_paths[] = {
"/lib",
"/lib/x86_64-linux-gnu",
"/lib64",
"/usr/lib",
"/usr/lib/x86_64-linux-gnu",
LIBDIR,
"/usr/local/lib",
NULL
}; // Note: this array is duplicated in src/fldd/main.c
extern void fslib_install_stdc(void);
extern void fslib_install_system(void);
static int lib_cnt = 0;
static int dir_cnt = 0;
static void report_duplication(const char *full_path) {
char *fname = strrchr(full_path, '/');
if (fname && *(++fname) != '\0') {
// report the file on all bin paths
int i = 0;
while (lib_paths[i]) {
char *p;
if (asprintf(&p, "%s/%s", lib_paths[i], fname) == -1)
errExit("asprintf");
fs_logger2("clone", p);
free(p);
i++;
}
}
}
static char *build_dest_dir(const char *full_path) {
assert(full_path);
if (strstr(full_path, "/x86_64-linux-gnu/"))
return RUN_LIB_DIR "/x86_64-linux-gnu";
return RUN_LIB_DIR;
}
// copy fname in private_run_dir
void fslib_duplicate(const char *full_path) {
assert(full_path);
struct stat s;
if (stat(full_path, &s) != 0 || s.st_uid != 0 || access(full_path, R_OK))
return;
char *dest_dir = build_dest_dir(full_path);
// don't copy it if the file is already there
char *ptr = strrchr(full_path, '/');
if (!ptr)
return;
ptr++;
if (*ptr == '\0')
return;
char *name;
if (asprintf(&name, "%s/%s", dest_dir, ptr) == -1)
errExit("asprintf");
if (stat(name, &s) == 0) {
free(name);
return;
}
free(name);
if (arg_debug || arg_debug_private_lib)
printf("copying %s to private %s\n", full_path, dest_dir);
sbox_run(SBOX_ROOT| SBOX_SECCOMP, 4, PATH_FCOPY, "--follow-link", full_path, dest_dir);
report_duplication(full_path);
lib_cnt++;
}
// requires full path for lib
// it could be a library or an executable
// lib is not copied, only libraries used by it
void fslib_copy_libs(const char *full_path) {
assert(full_path);
if (arg_debug || arg_debug_private_lib)
printf("fslib_copy_libs %s\n", full_path);
// if library/executable does not exist or the user does not have read access to it
// print a warning and exit the function.
if (access(full_path, R_OK)) {
if (arg_debug || arg_debug_private_lib)
printf("cannot find %s for private-lib, skipping...\n", full_path);
return;
}
// create an empty RUN_LIB_FILE and allow the user to write to it
unlink(RUN_LIB_FILE); // in case is there
create_empty_file_as_root(RUN_LIB_FILE, 0644);
if (chown(RUN_LIB_FILE, getuid(), getgid()))
errExit("chown");
// run fldd to extact the list of files
if (arg_debug || arg_debug_private_lib)
printf("running fldd %s\n", full_path);
sbox_run(SBOX_USER | SBOX_SECCOMP | SBOX_CAPS_NONE, 3, PATH_FLDD, full_path, RUN_LIB_FILE);
// open the list of libraries and install them on by one
FILE *fp = fopen(RUN_LIB_FILE, "r");
if (!fp)
errExit("fopen");
char buf[MAXBUF];
while (fgets(buf, MAXBUF, fp)) {
// remove \n
char *ptr = strchr(buf, '\n');
if (ptr)
*ptr = '\0';
fslib_duplicate(buf);
}
fclose(fp);
}
void fslib_copy_dir(const char *full_path) {
assert(full_path);
if (arg_debug || arg_debug_private_lib)
printf("fslib_copy_dir %s\n", full_path);
// do nothing if the directory does not exist or is not owned by root
struct stat s;
if (stat(full_path, &s) != 0 || s.st_uid != 0 || !S_ISDIR(s.st_mode) || access(full_path, R_OK))
return;
char *dir_name = strrchr(full_path, '/');
assert(dir_name);
dir_name++;
assert(*dir_name != '\0');
// do nothing if the directory is already there
char *dest;
if (asprintf(&dest, "%s/%s", build_dest_dir(full_path), dir_name) == -1)
errExit("asprintf");
if (stat(dest, &s) == 0) {
free(dest);
return;
}
// create new directory and mount the original on top of it
mkdir_attr(dest, 0755, 0, 0);
if (mount(full_path, dest, NULL, MS_BIND|MS_REC, NULL) < 0 ||
mount(NULL, dest, NULL, MS_BIND|MS_REMOUNT|MS_NOSUID|MS_NODEV|MS_REC, NULL) < 0)
errExit("mount bind");
fs_logger2("clone", full_path);
fs_logger2("mount", full_path);
dir_cnt++;
free(dest);
}
// return 1 if the file is valid
static char *valid_file(const char *lib) {
// filename check
int len = strlen(lib);
if (strcspn(lib, "\\&!?\"'<>%^(){}[];,*") != (size_t)len ||
strstr(lib, "..")) {
fprintf(stderr, "Error: \"%s\" is an invalid library\n", lib);
exit(1);
}
// find the library
int i;
for (i = 0; lib_paths[i]; i++) {
char *fname;
if (asprintf(&fname, "%s/%s", lib_paths[i], lib) == -1)
errExit("asprintf");
// existing file owned by root, read access
struct stat s;
if (stat(fname, &s) == 0 && s.st_uid == 0 && !access(fname, R_OK)) {
return fname;
}
free(fname);
}
fwarning("%s library not found, skipping...\n", lib);
return NULL;
}
static void mount_directories(void) {
if (arg_debug || arg_debug_private_lib)
printf("Mount-bind %s on top of /lib /lib64 /usr/lib\n", RUN_LIB_DIR);
if (is_dir("/lib")) {
if (mount(RUN_LIB_DIR, "/lib", NULL, MS_BIND|MS_REC, NULL) < 0 ||
mount(NULL, "/lib", NULL, MS_BIND|MS_REMOUNT|MS_NOSUID|MS_NODEV|MS_REC, NULL) < 0)
errExit("mount bind");
fs_logger2("tmpfs", "/lib");
fs_logger("mount /lib");
}
if (is_dir("/lib64")) {
if (mount(RUN_LIB_DIR, "/lib64", NULL, MS_BIND|MS_REC, NULL) < 0 ||
mount(NULL, "/lib64", NULL, MS_BIND|MS_REMOUNT|MS_NOSUID|MS_NODEV|MS_REC, NULL) < 0)
errExit("mount bind");
fs_logger2("tmpfs", "/lib64");
fs_logger("mount /lib64");
}
if (is_dir("/usr/lib")) {
if (mount(RUN_LIB_DIR, "/usr/lib", NULL, MS_BIND|MS_REC, NULL) < 0 ||
mount(NULL, "/usr/lib", NULL, MS_BIND|MS_REMOUNT|MS_NOSUID|MS_NODEV|MS_REC, NULL) < 0)
errExit("mount bind");
fs_logger2("tmpfs", "/usr/lib");
fs_logger("mount /usr/lib");
}
// for amd64 only - we'll deal with i386 later
if (is_dir("/lib32")) {
if (mount(RUN_RO_DIR, "/lib32", "none", MS_BIND, "mode=400,gid=0") < 0)
errExit("disable file");
fs_logger("blacklist-nolog /lib32");
}
if (is_dir("/libx32")) {
if (mount(RUN_RO_DIR, "/libx32", "none", MS_BIND, "mode=400,gid=0") < 0)
errExit("disable file");
fs_logger("blacklist-nolog /libx32");
}
}
void fs_private_lib(void) {
#ifndef __x86_64__
fwarning("private-lib feature is currently available only on amd64 platforms\n");
return;
#endif
char *private_list = cfg.lib_private_keep;
if (arg_debug || arg_debug_private_lib)
printf("Starting private-lib processing: program %s, shell %s\n",
(cfg.original_program_index > 0)? cfg.original_argv[cfg.original_program_index]: "none",
(arg_shell_none)? "none": cfg.shell);
// create /run/firejail/mnt/lib directory
mkdir_attr(RUN_LIB_DIR, 0755, 0, 0);
// install standard C libraries
fslib_install_stdc();
timetrace_start();
// copy the libs in the new lib directory for the main exe
if (cfg.original_program_index > 0)
fslib_copy_libs(cfg.original_argv[cfg.original_program_index]);
// for the shell
if (!arg_shell_none) {
fslib_copy_libs(cfg.shell);
// a shell is useless without ls command
fslib_copy_libs("/bin/ls");
}
// for the listed libs
if (private_list && *private_list != '\0') {
if (arg_debug || arg_debug_private_lib)
printf("Copying extra files (%s) in the new lib directory\n", private_list);
char *dlist = strdup(private_list);
if (!dlist)
errExit("strdup");
char *ptr = strtok(dlist, ",");
char *lib = valid_file(ptr);
if (lib) {
if (is_dir(lib))
fslib_copy_dir(lib);
else
fslib_copy_libs(lib);
fslib_copy_libs(lib);
free(lib);
}
while ((ptr = strtok(NULL, ",")) != NULL) {
lib = valid_file(ptr);
if (lib) {
if (is_dir(lib))
fslib_copy_dir(lib);
else
fslib_duplicate(lib);
fslib_copy_libs(lib);
free(lib);
}
}
free(dlist);
fs_logger_print();
}
// for private-bin files
if (arg_private_bin) {
FILE *fp = fopen(RUN_LIB_BIN, "r");
if (fp) {
char buf[MAXBUF];
while (fgets(buf, MAXBUF, fp)) {
// remove \n
char *ptr = strchr(buf, '\n');
if (ptr)
*ptr = '\0';
// copy libraries for this program
fslib_copy_libs(buf);
// load program data from /usr/lib/program or from /usr/lib/x86_64-linux-gnu
ptr = strrchr(buf, '/');
if (ptr && *(ptr + 1) != '\0') {
ptr++;
// /usr/lib/program
char *name;
if (asprintf(&name, "/usr/lib/%s", ptr) == -1)
errExit("asprintf");
if (is_dir(name)) {
fslib_copy_dir(name);
fslib_copy_libs(name);
}
free(name);
// /usr/lib/x86_linux-gnu - debian & frriends
if (asprintf(&name, "/usr/lib/x86_64-linux-gnu/%s", ptr) == -1)
errExit("asprintf");
if (is_dir(name)) {
fslib_copy_dir(name);
fslib_copy_libs(name);
}
free(name);
// /usr/lib64 - CentOS, Fedora
if (asprintf(&name, "/usr/lib64/%s", ptr) == -1)
errExit("asprintf");
if (is_dir(name)) {
fslib_copy_dir(name);
fslib_copy_libs(name);
}
free(name);
}
}
}
fclose(fp);
}
fmessage("Program libraries installed in %0.2f ms\n", timetrace_end());
// install the reset of the system libraries
fslib_install_system();
fmessage("Installed %d libraries and %d directories\n", lib_cnt, dir_cnt);
// bring in firejail directory for --trace options
fslib_copy_dir(LIBDIR "/firejail");
// ... and for sandbox in sandbox functionality
fslib_copy_libs(LIBDIR "/firejail/faudit");
fslib_copy_libs(LIBDIR "/firejail/fbuilder");
fslib_copy_libs(LIBDIR "/firejail/fcopy");
fslib_copy_libs(LIBDIR "/firejail/fldd");
fslib_copy_libs(LIBDIR "/firejail/fnet");
fslib_copy_libs(LIBDIR "/firejail/fnetfilter");
fslib_copy_libs(LIBDIR "/firejail/fseccomp");
fslib_copy_libs(LIBDIR "/firejail/ftee");
// mount lib filesystem
mount_directories();
}
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