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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 <elf.h>
#include <fcntl.h>
#include <sys/mman.h>
#include <sys/mount.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>
#ifdef __LP64__
#define Elf_Ehdr Elf64_Ehdr
#define Elf_Phdr Elf64_Phdr
#define Elf_Shdr Elf64_Shdr
#define Elf_Dyn Elf64_Dyn
#else
#define Elf_Ehdr Elf32_Ehdr
#define Elf_Phdr Elf32_Phdr
#define Elf_Shdr Elf32_Shdr
#define Elf_Dyn Elf32_Dyn
#endif
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
};
static void copy_libs_for_lib(const char *lib, const char *private_run_dir);
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);
}
static void copy_libs_for_exe(const char *exe, const char *private_run_dir) {
if (arg_debug)
printf("copy libs for %s\n", exe);
int f;
f = open(exe, O_RDONLY);
if (f < 0)
return;
struct stat s;
char *base = NULL;
if (fstat(f, &s) == -1)
goto error_close;
base = mmap(0, s.st_size, PROT_READ | PROT_WRITE, MAP_PRIVATE, f, 0);
if (base == MAP_FAILED)
goto error_close;
Elf_Ehdr *ebuf = (Elf_Ehdr *)base;
if (strncmp((const char *)ebuf->e_ident, ELFMAG, SELFMAG) != 0)
goto close;
Elf_Phdr *pbuf = (Elf_Phdr *)(base + sizeof(*ebuf));
while (ebuf->e_phnum-- > 0) {
switch (pbuf->p_type) {
case PT_INTERP:
// dynamic loader ld-linux.so
duplicate(base + pbuf->p_offset, private_run_dir);
break;
}
pbuf++;
}
Elf_Shdr *sbuf = (Elf_Shdr *)(base + ebuf->e_shoff);
// Find strings section
char *strbase = NULL;
int sections = ebuf->e_shnum;
while (sections-- > 0) {
if (sbuf->sh_type == SHT_STRTAB) {
strbase = base + sbuf->sh_offset;
break;
}
sbuf++;
}
if (strbase == NULL)
goto error_close;
// Find dynamic section
sections = ebuf->e_shnum;
while (sections-- > 0) {
if (sbuf->sh_type == SHT_DYNAMIC) {
// Find DT_NEEDED tags
Elf_Dyn *dbuf = (Elf_Dyn *)(base + sbuf->sh_offset);
while (sbuf->sh_size >= sizeof(*dbuf)) {
if (dbuf->d_tag == DT_NEEDED) {
const char *lib = strbase + dbuf->d_un.d_ptr;
copy_libs_for_lib(lib, private_run_dir);
}
sbuf->sh_size -= sizeof(*dbuf);
dbuf++;
}
}
sbuf++;
}
goto close;
error_close:
perror("copy libs");
close:
if (base)
munmap(base, s.st_size);
close(f);
}
static void copy_libs_for_lib(const char *lib, const char *private_run_dir) {
int i;
for (i = 0; lib_paths[i]; i++) {
char *fname;
if (asprintf(&fname, "%s/%s", lib_paths[i], lib) == -1)
errExit("asprintf");
if (access(fname, R_OK) == 0) {
char *dst;
if (asprintf(&dst, "%s/%s", private_run_dir, lib) == -1)
errExit("asprintf");
if (access(dst, R_OK) != 0) {
duplicate(fname, private_run_dir);
// libs may need other libs
copy_libs_for_exe(fname, private_run_dir);
}
free(dst);
free(fname);
return;
}
free(fname);
}
errExit("library not found");
}
void fs_private_lib(void) {
char *private_list = cfg.lib_private_keep;
// create /run/firejail/mnt/lib directory
mkdir_attr(RUN_LIB_DIR, 0755, 0, 0);
// copy the libs in the new lib directory for the main exe
if (cfg.original_program_index > 0)
copy_libs_for_exe(cfg.original_argv[cfg.original_program_index], RUN_LIB_DIR);
// for the shell
if (!arg_shell_none)
copy_libs_for_exe(cfg.shell, RUN_LIB_DIR);
// 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, ",");
copy_libs_for_lib(ptr, RUN_LIB_DIR);
while ((ptr = strtok(NULL, ",")) != NULL)
copy_libs_for_lib(ptr, RUN_LIB_DIR);
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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