/* Copyright (c) 2012 The Chromium OS Authors. All rights reserved.
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#include <dlfcn.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include "libminijail.h"
#include "libsyscalls.h"
#include "elfparse.h"
#include "util.h"
static void set_user(struct minijail *j, const char *arg)
{
char *end = NULL;
int uid = strtod(arg, &end);
if (!*end && *arg) {
minijail_change_uid(j, uid);
return;
}
if (minijail_change_user(j, arg)) {
fprintf(stderr, "Bad user: '%s'\n", arg);
exit(1);
}
}
static void set_group(struct minijail *j, const char *arg)
{
char *end = NULL;
int gid = strtod(arg, &end);
if (!*end && *arg) {
minijail_change_gid(j, gid);
return;
}
if (minijail_change_group(j, arg)) {
fprintf(stderr, "Bad group: '%s'\n", arg);
exit(1);
}
}
static void use_caps(struct minijail *j, const char *arg)
{
uint64_t caps;
char *end = NULL;
caps = strtoull(arg, &end, 16);
if (*end) {
fprintf(stderr, "Invalid cap set: '%s'\n", arg);
exit(1);
}
minijail_use_caps(j, caps);
}
static void add_binding(struct minijail *j, char *arg)
{
char *src = strtok(arg, ",");
char *dest = strtok(NULL, ",");
char *flags = strtok(NULL, ",");
if (!src || !dest) {
fprintf(stderr, "Bad binding: %s %s\n", src, dest);
exit(1);
}
if (minijail_bind(j, src, dest, flags ? atoi(flags) : 0)) {
fprintf(stderr, "minijail_bind failed.\n");
exit(1);
}
}
static void add_mount(struct minijail *j, char *arg)
{
char *src = strtok(arg, ",");
char *dest = strtok(NULL, ",");
char *type = strtok(NULL, ",");
char *flags = strtok(NULL, ",");
if (!src || !dest || !type) {
fprintf(stderr, "Bad mount: %s %s %s\n", src, dest, type);
exit(1);
}
if (minijail_mount(j, src, dest, type,
flags ? strtoul(flags, NULL, 16) : 0)) {
fprintf(stderr, "minijail_mount failed.\n");
exit(1);
}
}
static void usage(const char *progn)
{
size_t i;
printf("Usage: %s [-GhiInprsvtUl] [-b <src>,<dest>[,<writeable>]] [-f <file>]"
"[-c <caps>] [-C <dir>] [-g <group>] [-S <file>] [-u <user>] "
"[-k <src>,<dest>,<type>[,<flags>]] "
"[-m \"<uid> <loweruid> <count>[,<uid> <loweruid> <count>]\"] "
"[-M \"<gid> <lowergid> <count>[,<uid> <loweruid> <count>]\"] "
"<program> [args...]\n"
" -a <table>: use alternate syscall table <table>\n"
" -b: binds <src> to <dest> in chroot. Multiple "
"instances allowed\n"
" -k: mount <src> to <dest> in chroot. Multiple "
"instances allowed, flags are passed to mount(2)\n"
" -c <caps>: restrict caps to <caps>\n"
" -C <dir>: chroot to <dir>\n"
" Not compatible with -P\n"
" -e[file]: enter new network namespace, or existing one if 'file' is provided\n"
" -f <file>: write the pid of the jailed process to <file>\n"
" -G: inherit secondary groups from uid\n"
" -g <group>: change gid to <group>\n"
" -h: help (this message)\n"
" -H: seccomp filter help message\n"
" -i: exit immediately after fork (do not act as init)\n"
" Not compatible with -p\n"
" -I: run <program> as init (pid 1) inside a new pid namespace (implies -p)\n"
" -l: enter new IPC namespace\n"
" -L: report blocked syscalls to syslog when using seccomp filter.\n"
" Forces the following syscalls to be allowed:\n"
" ", progn);
for (i = 0; i < log_syscalls_len; i++)
printf("%s ", log_syscalls[i]);
printf("\n"
" -m: set the uid mapping of a user namespace (implies -pU).\n"
" Same arguments as newuidmap(1), multiple mappings should be separated by ',' (comma).\n"
" Not compatible with -b without writable\n"
" -M: set the gid mapping of a user namespace (implies -pU).\n"
" Same arguments as newgidmap(1), multiple mappings should be separated by ',' (comma).\n"
" Not compatible with -b without writable\n"
" -n: set no_new_privs\n"
" -p: enter new pid namespace (implies -vr)\n"
" -P <dir>: pivot_root to <dir> (implies -v)\n"
" Not compatible with -C\n"
" -r: remount /proc read-only (implies -v)\n"
" -s: use seccomp\n"
" -S <file>: set seccomp filter using <file>\n"
" E.g., -S /usr/share/filters/<prog>.$(uname -m)\n"
" Requires -n when not running as root\n"
" -t: mount tmpfs at /tmp inside chroot\n"
" -u <user>: change uid to <user>\n"
" -U enter new user namespace (implies -p)\n"
" -v: enter new mount namespace\n"
" -V <file>: enter specified mount namespace\n");
}
static void seccomp_filter_usage(const char *progn)
{
const struct syscall_entry *entry = syscall_table;
printf("Usage: %s -S <policy.file> <program> [args...]\n\n"
"System call names supported:\n", progn);
for (; entry->name && entry->nr >= 0; ++entry)
printf(" %s [%d]\n", entry->name, entry->nr);
printf("\nSee minijail0(5) for example policies.\n");
}
static int parse_args(struct minijail *j, int argc, char *argv[],
int *exit_immediately)
{
int opt;
int use_seccomp_filter = 0;
int binding = 0;
int pivot_root = 0, chroot = 0;
const size_t path_max = 4096;
const char *filter_path;
if (argc > 1 && argv[1][0] != '-')
return 1;
while ((opt = getopt(argc, argv,
"u:g:sS:c:C:P:b:V:f:m:M:k:a:e::vrGhHinplLtIU"))
!= -1) {
switch (opt) {
case 'u':
set_user(j, optarg);
break;
case 'g':
set_group(j, optarg);
break;
case 'n':
minijail_no_new_privs(j);
break;
case 's':
minijail_use_seccomp(j);
break;
case 'S':
minijail_use_seccomp_filter(j);
if (strlen(optarg) >= path_max) {
fprintf(stderr, "Filter path is too long.\n");
exit(1);
}
filter_path = strndup(optarg, path_max);
if (!filter_path) {
fprintf(stderr,
"Could not strndup(3) filter path.\n");
exit(1);
}
use_seccomp_filter = 1;
break;
case 'l':
minijail_namespace_ipc(j);
break;
case 'L':
minijail_log_seccomp_filter_failures(j);
break;
case 'b':
add_binding(j, optarg);
binding = 1;
break;
case 'c':
use_caps(j, optarg);
break;
case 'C':
if (pivot_root) {
fprintf(stderr, "Could not set chroot because "
"'-P' was specified.\n");
exit(1);
}
if (0 != minijail_enter_chroot(j, optarg)) {
fprintf(stderr, "Could not set chroot.\n");
exit(1);
}
chroot = 1;
break;
case 'k':
add_mount(j, optarg);
break;
case 'P':
if (chroot) {
fprintf(stderr,
"Could not set pivot_root because "
"'-C' was specified.\n");
exit(1);
}
if (0 != minijail_enter_pivot_root(j, optarg)) {
fprintf(stderr, "Could not set pivot_root.\n");
exit(1);
}
minijail_namespace_vfs(j);
pivot_root = 1;
break;
case 'f':
if (0 != minijail_write_pid_file(j, optarg)) {
fprintf(stderr,
"Could not prepare pid file path.\n");
exit(1);
}
break;
case 't':
minijail_mount_tmp(j);
break;
case 'v':
minijail_namespace_vfs(j);
break;
case 'V':
minijail_namespace_enter_vfs(j, optarg);
break;
case 'r':
minijail_remount_proc_readonly(j);
break;
case 'G':
minijail_inherit_usergroups(j);
break;
case 'p':
minijail_namespace_pids(j);
break;
case 'e':
if (optarg)
minijail_namespace_enter_net(j, optarg);
else
minijail_namespace_net(j);
break;
case 'i':
*exit_immediately = 1;
break;
case 'H':
seccomp_filter_usage(argv[0]);
exit(1);
case 'I':
minijail_namespace_pids(j);
minijail_run_as_init(j);
break;
case 'U':
minijail_namespace_user(j);
minijail_namespace_pids(j);
break;
case 'm':
minijail_namespace_user(j);
minijail_namespace_pids(j);
if (0 != minijail_uidmap(j, optarg)) {
fprintf(stderr, "Could not set uidmap.\n");
exit(1);
}
break;
case 'M':
minijail_namespace_user(j);
minijail_namespace_pids(j);
if (0 != minijail_gidmap(j, optarg)) {
fprintf(stderr, "Could not set gidmap.\n");
exit(1);
}
break;
case 'a':
if (0 != minijail_use_alt_syscall(j, optarg)) {
fprintf(stderr,
"Could not set alt-syscall table.\n");
exit(1);
}
break;
default:
usage(argv[0]);
exit(1);
}
if (optind < argc && argv[optind][0] != '-')
break;
}
/* Only allow bind mounts when entering a chroot or using pivot_root. */
if (binding && !(chroot || pivot_root)) {
fprintf(stderr, "Can't add bind mounts without chroot or"
" pivot_root.\n");
exit(1);
}
/*
* We parse seccomp filters here to make sure we've collected all
* cmdline options.
*/
if (use_seccomp_filter) {
minijail_parse_seccomp_filters(j, filter_path);
free((void*)filter_path);
}
if (argc == optind) {
usage(argv[0]);
exit(1);
}
return optind;
}
int main(int argc, char *argv[])
{
struct minijail *j = minijail_new();
const char *dl_mesg = NULL;
int exit_immediately = 0;
char *program_path;
int consumed = parse_args(j, argc, argv, &exit_immediately);
ElfType elftype = ELFERROR;
argc -= consumed;
argv += consumed;
/* Get the path to the program adjusted for changing root. */
program_path = minijail_get_original_path(j, argv[0]);
/* Check that we can access the target program. */
if (access(program_path, X_OK)) {
fprintf(stderr, "Target program '%s' is not accessible.\n",
argv[0]);
return 1;
}
/* Check if target is statically or dynamically linked. */
elftype = get_elf_linkage(program_path);
if (elftype == ELFSTATIC) {
/*
* Target binary is statically linked so we cannot use
* libminijailpreload.so.
*/
minijail_run_no_preload(j, argv[0], argv);
} else if (elftype == ELFDYNAMIC) {
/*
* Target binary is dynamically linked so we can
* inject libminijailpreload.so into it.
*/
/* Check that we can dlopen() libminijailpreload.so. */
if (!dlopen(PRELOADPATH, RTLD_LAZY | RTLD_LOCAL)) {
dl_mesg = dlerror();
fprintf(stderr, "dlopen(): %s\n", dl_mesg);
return 1;
}
minijail_run(j, argv[0], argv);
} else {
fprintf(stderr,
"Target program '%s' is not a valid ELF file.\n",
argv[0]);
return 1;
}
free(program_path);
if (exit_immediately) {
info("not running init loop, exiting immediately");
return 0;
}
return minijail_wait(j);
}