2 * Copyright (C) 2015 John Crispin <blogic@openwrt.org>
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU Lesser General Public License version 2.1
6 * as published by the Free Software Foundation
8 * This program is distributed in the hope that it will be useful,
9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
11 * GNU General Public License for more details.
15 #include <sys/mount.h>
16 #include <sys/prctl.h>
30 #include "capabilities.h"
33 #include <libubox/list.h>
34 #include <libubox/uloop.h>
36 #define STACK_SIZE (1024 * 1024)
37 #define OPT_ARGS "P:S:C:n:r:w:d:psulo"
52 struct list_head list
;
59 static LIST_HEAD(extras
);
61 extern int pivot_root(const char *new_root
, const char *put_old
);
65 static char child_stack
[STACK_SIZE
];
67 static int mkdir_p(char *dir
, mode_t mask
)
69 char *l
= strrchr(dir
, '/');
77 if (mkdir_p(dir
, mask
))
82 ret
= mkdir(dir
, mask
);
83 if (ret
&& errno
== EEXIST
)
87 ERROR("mkdir failed on %s: %s\n", dir
, strerror(errno
));
92 static int mount_bind(const char *root
, const char *path
, const char *name
, int readonly
, int error
)
100 if (strstr(p
, "local"))
103 snprintf(old
, sizeof(old
), "%s/%s", path
, name
);
104 snprintf(new, sizeof(new), "%s%s", root
, p
);
108 snprintf(new, sizeof(new), "%s%s/%s", root
, p
, name
);
111 ERROR("%s does not exist\n", old
);
115 if (S_ISDIR(s
.st_mode
)) {
118 fd
= creat(new, 0644);
120 ERROR("failed to create %s: %s\n", new, strerror(errno
));
126 if (mount(old
, new, NULL
, MS_BIND
, NULL
)) {
127 ERROR("failed to mount -B %s %s: %s\n", old
, new, strerror(errno
));
131 if (readonly
&& mount(NULL
, new, NULL
, MS_BIND
| MS_REMOUNT
| MS_RDONLY
, NULL
)) {
132 ERROR("failed to remount ro %s: %s\n", new, strerror(errno
));
136 DEBUG("mount -B %s %s\n", old
, new);
141 static int build_jail_fs()
146 if (mount("tmpfs", opts
.path
, "tmpfs", MS_NOATIME
, "mode=0755")) {
147 ERROR("tmpfs mount failed %s\n", strerror(errno
));
151 if (chdir(opts
.path
)) {
152 ERROR("failed to chdir() in the jail root\n");
156 avl_init(&libraries
, avl_strcmp
, false, NULL
);
157 alloc_library_path("/lib64");
158 alloc_library_path("/lib");
159 alloc_library_path("/usr/lib");
160 load_ldso_conf("/etc/ld.so.conf");
162 if (elf_load_deps(*opts
.jail_argv
)) {
163 ERROR("failed to load dependencies\n");
167 if (opts
.seccomp
&& elf_load_deps("libpreload-seccomp.so")) {
168 ERROR("failed to load libpreload-seccomp.so\n");
172 avl_for_each_element(&libraries
, l
, avl
)
173 if (mount_bind(opts
.path
, l
->path
, l
->name
, 1, -1))
176 list_for_each_entry(m
, &extras
, list
)
177 if (mount_bind(opts
.path
, m
->path
, m
->name
, m
->readonly
, 0))
181 if (asprintf(&mpoint
, "%s/old", opts
.path
) < 0) {
182 ERROR("failed to alloc pivot path: %s\n", strerror(errno
));
185 mkdir_p(mpoint
, 0755);
186 if (pivot_root(opts
.path
, mpoint
) == -1) {
187 ERROR("pivot_root failed:%s\n", strerror(errno
));
192 umount2("/old", MNT_DETACH
);
195 mkdir("/proc", 0755);
196 mount("proc", "/proc", "proc", MS_NOATIME
| MS_NODEV
| MS_NOEXEC
| MS_NOSUID
, 0);
200 mount("sysfs", "/sys", "sysfs", MS_NOATIME
| MS_NODEV
| MS_NOEXEC
| MS_NOSUID
, 0);
203 mount(NULL
, "/", NULL
, MS_RDONLY
| MS_REMOUNT
, 0);
209 static char** build_envp(const char *seccomp
)
211 static char *envp
[MAX_ENVP
];
212 static char preload_var
[64];
213 static char seccomp_var
[64];
214 static char debug_var
[] = "LD_DEBUG=all";
215 const char *preload_lib
= find_lib("libpreload-seccomp.so");
218 if (seccomp
&& !preload_lib
) {
219 ERROR("failed to add preload-lib to env\n");
223 snprintf(seccomp_var
, sizeof(seccomp_var
), "SECCOMP_FILE=%s", seccomp
);
224 envp
[count
++] = seccomp_var
;
225 snprintf(preload_var
, sizeof(preload_var
), "LD_PRELOAD=%s", preload_lib
);
226 envp
[count
++] = preload_var
;
229 envp
[count
++] = debug_var
;
234 static void usage(void)
236 fprintf(stderr
, "ujail <options> -- <binary> <params ...>\n");
237 fprintf(stderr
, " -d <num>\tshow debug log (increase num to increase verbosity)\n");
238 fprintf(stderr
, " -S <file>\tseccomp filter config\n");
239 fprintf(stderr
, " -C <file>\tcapabilities drop config\n");
240 fprintf(stderr
, " -n <name>\tthe name of the jail\n");
241 fprintf(stderr
, "namespace jail options:\n");
242 fprintf(stderr
, " -P <path>\tpath where the jail will be staged\n");
243 fprintf(stderr
, " -r <file>\treadonly files that should be staged\n");
244 fprintf(stderr
, " -w <file>\twriteable files that should be staged\n");
245 fprintf(stderr
, " -p\t\tjail has /proc\n");
246 fprintf(stderr
, " -s\t\tjail has /sys\n");
247 fprintf(stderr
, " -l\t\tjail has /dev/log\n");
248 fprintf(stderr
, " -u\t\tjail has a ubus socket\n");
249 fprintf(stderr
, " -o\t\tremont jail root (/) read only\n");
250 fprintf(stderr
, "\nWarning: by default root inside the jail is the same\n\
251 and he has the same powers as root outside the jail,\n\
252 thus he can escape the jail and/or break stuff.\n\
253 Please use seccomp/capabilities (-S/-C) to restrict his powers\n\n\
254 If you use none of the namespace jail options,\n\
255 ujail will not use namespace/build a jail,\n\
256 and will only drop capabilities/apply seccomp filter.\n\n");
259 static int exec_jail()
261 char **envp
= build_envp(opts
.seccomp
);
265 if (opts
.capabilities
&& drop_capabilities(opts
.capabilities
))
268 INFO("exec-ing %s\n", *opts
.jail_argv
);
269 execve(*opts
.jail_argv
, opts
.jail_argv
, envp
);
270 //we get there only if execve fails
271 ERROR("failed to execve %s: %s\n", *opts
.jail_argv
, strerror(errno
));
275 static int spawn_jail(void *_notused
)
277 if (opts
.name
&& sethostname(opts
.name
, strlen(opts
.name
))) {
278 ERROR("failed to sethostname: %s\n", strerror(errno
));
281 if (build_jail_fs()) {
282 ERROR("failed to build jail fs");
289 static int jail_running
= 1;
290 static int jail_return_code
= 0;
292 static void jail_process_handler(struct uloop_process
*c
, int ret
)
294 if (WIFEXITED(ret
)) {
295 jail_return_code
= WEXITSTATUS(ret
);
296 INFO("jail (%d) exited with exit: %d\n", c
->pid
, jail_return_code
);
298 jail_return_code
= WTERMSIG(ret
);
299 INFO("jail (%d) exited with signal: %d\n", c
->pid
, jail_return_code
);
305 static struct uloop_process jail_process
= {
306 .cb
= jail_process_handler
,
309 static void add_extra(char *name
, int readonly
)
314 ERROR("%s is not an absolute path\n", name
);
318 f
= calloc(1, sizeof(struct extra
));
320 f
->name
= basename(name
);
321 f
->path
= dirname(strdup(name
));
322 f
->readonly
= readonly
;
324 list_add_tail(&f
->list
, &extras
);
327 int main(int argc
, char **argv
)
329 uid_t uid
= getuid();
330 char log
[] = "/dev/log";
331 char ubus
[] = "/var/run/ubus.sock";
332 int ret
= EXIT_SUCCESS
;
336 ERROR("not root, aborting: %s\n", strerror(errno
));
342 while ((ch
= getopt(argc
, argv
, OPT_ARGS
)) != -1) {
345 debug
= atoi(optarg
);
360 opts
.seccomp
= optarg
;
361 add_extra(optarg
, 1);
364 opts
.capabilities
= optarg
;
365 add_extra(optarg
, 1);
376 add_extra(optarg
, 1);
380 add_extra(optarg
, 0);
393 //no <binary> param found
394 if (argc
- optind
< 1) {
398 if (!(opts
.namespace||opts
.capabilities
||opts
.seccomp
)) {
399 ERROR("Not using namespaces, capabilities or seccomp !!!\n\n");
403 DEBUG("Using namespaces(%d), capabilities(%d), seccomp(%d)\n",
405 opts
.capabilities
!= 0,
408 opts
.jail_argv
= &argv
[optind
];
411 prctl(PR_SET_NAME
, opts
.name
, NULL
, NULL
, NULL
);
413 if (opts
.namespace && !opts
.path
&& asprintf(&opts
.path
, "/tmp/%s", basename(*opts
.jail_argv
)) == -1) {
414 ERROR("failed to asprintf root path: %s\n", strerror(errno
));
418 if (opts
.namespace && mkdir(opts
.path
, 0755)) {
419 ERROR("unable to create root path: %s (%s)\n", opts
.path
, strerror(errno
));
424 if (opts
.namespace) {
425 jail_process
.pid
= clone(spawn_jail
,
426 child_stack
+ STACK_SIZE
,
427 CLONE_NEWUTS
| CLONE_NEWPID
| CLONE_NEWNS
| CLONE_NEWIPC
| SIGCHLD
, NULL
);
429 jail_process
.pid
= fork();
432 if (jail_process
.pid
> 0) {
434 uloop_process_add(&jail_process
);
438 DEBUG("uloop interrupted, killing jail process\n");
439 kill(jail_process
.pid
, SIGTERM
);
440 waitpid(jail_process
.pid
, NULL
, 0);
442 } else if (jail_process
.pid
== 0) {
446 ERROR("failed to clone/fork: %s\n", strerror(errno
));
450 if (opts
.namespace && rmdir(opts
.path
)) {
451 ERROR("Unable to remove root path: %s (%s)\n", opts
.path
, strerror(errno
));
458 return jail_return_code
;