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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>
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
static void copy_libs(const char *exe, const char *dir, const char *file);
static void duplicate(const char *fname, const char *private_run_dir) {
if (arg_debug)
printf("copying %s to private %s\n", fname, private_run_dir);
sbox_run(SBOX_ROOT| SBOX_SECCOMP, 4, PATH_FCOPY, "--follow-link", fname, private_run_dir);
}
// requires full path for exe
static void copy_exe(const char *exe, const char *dir, const char *file) {
// if exe does not exist or the user does not have read access to it
// print a warning and exit the function.
if (access(exe, R_OK)) {
fwarning("cannot find %s executable for private-lib, skipping...\n", exe);
return;
}
copy_libs(exe, dir, file);
}
// requires full path for lib
static void copy_libs(const char *lib, const char *dir, const char *output_file) {
// create an empty RUN_LIB_FILE and allow the user to write to it
unlink(output_file); // in case is there
create_empty_file_as_root(output_file, 0644);
if (chown(output_file, getuid(), getgid()))
errExit("chown");
// run fldd to extact the list of file
sbox_run(SBOX_USER | SBOX_SECCOMP | SBOX_CAPS_NONE, 3, PATH_FLDD, lib, output_file);
// open the list of libraries and install them on by one
FILE *fp = fopen(output_file, "r");
if (!fp)
errExit("fopen");
#define MAXBUF 4096
char buf[MAXBUF];
while (fgets(buf, MAXBUF, fp)) {
// remove \n
char *ptr = strchr(buf, '\n');
if (ptr)
*ptr = '\0';
duplicate(buf, dir);
}
fclose(fp);
}
// return 1 if the file is valid
static char *valid_library(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
struct stat s;
if (stat(fname, &s) == 0 && s.st_uid == 0) {
return fname;
}
free(fname);
}
fwarning("%s library not found, skipping...\n", lib);
return NULL;
}
void fs_private_lib(void) {
char *private_list = cfg.lib_private_keep;
if (arg_debug)
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);
// fix libselinux linking problem on Debian stretch; the library is
// linked in most basic command utilities (ls, cp, find etc.), and it
// seems to have a path hardlinked under /lib/x86_64-linux-gnu directory.
struct stat s;
if (stat("/lib/x86_64-linux-gnu/libselinux.so.1", &s) == 0) {
mkdir_attr(RUN_LIB_DIR "/x86_64-linux-gnu", 0755, 0, 0);
duplicate("/lib/x86_64-linux-gnu/libselinux.so.1", RUN_LIB_DIR "/x86_64-linux-gnu");
}
// copy the libs in the new lib directory for the main exe
if (cfg.original_program_index > 0)
copy_exe(cfg.original_argv[cfg.original_program_index], RUN_LIB_DIR, RUN_LIB_FILE);
// for the shell
if (!arg_shell_none) {
copy_exe(cfg.shell, RUN_LIB_DIR, RUN_LIB_FILE);
// a shell is useless without ls command
copy_libs("/bin/ls", RUN_LIB_DIR, RUN_LIB_FILE);
}
// for the listed libs
if (private_list && *private_list != '\0') {
if (arg_debug)
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_library(ptr);
if (lib) {
duplicate(lib, RUN_LIB_DIR);
copy_libs(lib, RUN_LIB_DIR, RUN_LIB_FILE);
free(lib);
}
while ((ptr = strtok(NULL, ",")) != NULL) {
lib = valid_library(ptr);
if (lib) {
duplicate(lib, RUN_LIB_DIR);
copy_libs(lib, RUN_LIB_DIR, RUN_LIB_FILE);
free(lib);
}
}
free(dlist);
fs_logger_print();
}
// for our trace and tracelog libs
if (arg_trace)
duplicate(LIBDIR "/firejail/libtrace.so", RUN_LIB_DIR);
else if (arg_tracelog)
duplicate(LIBDIR "/firejail/libtracelog.so", RUN_LIB_DIR);
if (arg_debug)
printf("Mount-bind %s on top of /lib /lib64 /usr/lib\n", RUN_LIB_DIR);
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_logger("mount /lib");
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_logger("mount /lib64");
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_logger("mount /usr/lib");
}
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