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-rw-r--r--jail/jail.c393
1 files changed, 157 insertions, 236 deletions
diff --git a/jail/jail.c b/jail/jail.c
index 2bba292..f8139b8 100644
--- a/jail/jail.c
+++ b/jail/jail.c
@@ -43,7 +43,17 @@
#include <libubox/uloop.h>
#define STACK_SIZE (1024 * 1024)
-#define OPT_ARGS "P:S:n:r:w:psuldo"
+#define OPT_ARGS "P:S:n:r:w:d:psulo"
+
+static struct {
+ char *path;
+ char *name;
+ char **jail_argv;
+ char *seccomp;
+ int procfs;
+ int ronly;
+ int sysfs;
+} opts;
struct extra {
struct list_head list;
@@ -125,7 +135,7 @@ static int mount_bind(const char *root, const char *path, const char *name, int
return -1;
}
- if (readonly && mount(old, new, NULL, MS_BIND | MS_REMOUNT | MS_RDONLY, NULL)) {
+ if (readonly && mount(NULL, new, NULL, MS_BIND | MS_REMOUNT | MS_RDONLY, NULL)) {
ERROR("failed to remount ro %s: %s\n", new, strerror(errno));
return -1;
}
@@ -135,80 +145,75 @@ static int mount_bind(const char *root, const char *path, const char *name, int
return 0;
}
-static int build_jail(const char *path)
+static int build_jail_fs()
{
struct library *l;
struct extra *m;
- int ret = 0;
- mkdir(path, 0755);
-
- if (mount("tmpfs", path, "tmpfs", MS_NOATIME, "mode=0755")) {
+ if (mount("tmpfs", opts.path, "tmpfs", MS_NOATIME, "mode=0755")) {
ERROR("tmpfs mount failed %s\n", strerror(errno));
return -1;
}
- avl_for_each_element(&libraries, l, avl)
- if (mount_bind(path, l->path, l->name, 1, -1))
- return -1;
-
- list_for_each_entry(m, &extras, list)
- if (mount_bind(path, m->path, m->name, m->readonly, 0))
- return -1;
-
- return ret;
-}
+ if (chdir(opts.path)) {
+ ERROR("failed to chdir() in the jail root\n");
+ return -1;
+ }
-static void _umount(const char *root, const char *path)
-{
- char *buf = NULL;
+ avl_init(&libraries, avl_strcmp, false, NULL);
+ alloc_library_path("/lib64");
+ alloc_library_path("/lib");
+ alloc_library_path("/usr/lib");
+ load_ldso_conf("/etc/ld.so.conf");
- if (asprintf(&buf, "%s%s", root, path) < 0) {
- ERROR("failed to alloc umount buffer: %s\n", strerror(errno));
- } else {
- DEBUG("umount %s\n", buf);
- umount(buf);
- free(buf);
+ if (elf_load_deps(*opts.jail_argv)) {
+ ERROR("failed to load dependencies\n");
+ return -1;
}
-}
-static int stop_jail(const char *root)
-{
- struct library *l;
- struct extra *m;
+ if (opts.seccomp && elf_load_deps("libpreload-seccomp.so")) {
+ ERROR("failed to load libpreload-seccomp.so\n");
+ return -1;
+ }
- avl_for_each_element(&libraries, l, avl) {
- char path[256];
- char *p = l->path;
+ avl_for_each_element(&libraries, l, avl)
+ if (mount_bind(opts.path, l->path, l->name, 1, -1))
+ return -1;
- if (strstr(p, "local"))
- p = "/lib";
+ list_for_each_entry(m, &extras, list)
+ if (mount_bind(opts.path, m->path, m->name, m->readonly, 0))
+ return -1;
- snprintf(path, sizeof(path), "%s%s/%s", root, p, l->name);
- DEBUG("umount %s\n", path);
- umount(path);
+ char *mpoint;
+ if (asprintf(&mpoint, "%s/old", opts.path) < 0) {
+ ERROR("failed to alloc pivot path: %s\n", strerror(errno));
+ return -1;
}
-
- list_for_each_entry(m, &extras, list) {
- char path[256];
-
- snprintf(path, sizeof(path), "%s%s/%s", root, m->path, m->name);
- DEBUG("umount %s\n", path);
- umount(path);
+ mkdir_p(mpoint, 0755);
+ if (pivot_root(opts.path, mpoint) == -1) {
+ ERROR("pivot_root failed:%s\n", strerror(errno));
+ free(mpoint);
+ return -1;
}
-
- _umount(root, "/proc");
- _umount(root, "/sys");
-
- DEBUG("umount %s\n", root);
- umount(root);
- rmdir(root);
+ free(mpoint);
+ umount2("/old", MNT_DETACH);
+ rmdir("/old");
+ if (opts.procfs) {
+ mkdir("/proc", 0755);
+ mount("proc", "/proc", "proc", MS_NOATIME, 0);
+ }
+ if (opts.sysfs) {
+ mkdir("/sys", 0755);
+ mount("sysfs", "/sys", "sysfs", MS_NOATIME, 0);
+ }
+ if (opts.ronly)
+ mount(NULL, "/", NULL, MS_RDONLY | MS_REMOUNT, 0);
return 0;
}
#define MAX_ENVP 8
-static char** build_envp(const char *seccomp, int debug)
+static char** build_envp(const char *seccomp)
{
static char *envp[MAX_ENVP];
static char preload_var[64];
@@ -227,177 +232,77 @@ static char** build_envp(const char *seccomp, int debug)
snprintf(preload_var, sizeof(preload_var), "LD_PRELOAD=%s", preload_lib);
envp[count++] = preload_var;
}
- if (debug)
+ if (debug > 1)
envp[count++] = debug_var;
return envp;
}
-static int spawn(const char *path, char **argv, const char *seccomp)
-{
- pid_t pid = fork();
-
- if (pid < 0) {
- ERROR("failed to spawn %s: %s\n", *argv, strerror(errno));
- return -1;
- } else if (!pid) {
- char **envp = build_envp(seccomp, 0);
-
- INFO("spawning %s\n", *argv);
- execve(*argv, argv, envp);
- ERROR("failed to spawn child %s: %s\n", *argv, strerror(errno));
- exit(-1);
- }
-
- return pid;
-}
-
-static int usage(void)
+static void usage(void)
{
- fprintf(stderr, "jail <options> -D <binary> <params ...>\n");
+ fprintf(stderr, "ujail <options> -- <binary> <params ...>\n");
fprintf(stderr, " -P <path>\tpath where the jail will be staged\n");
fprintf(stderr, " -S <file>\tseccomp filter\n");
fprintf(stderr, " -n <name>\tthe name of the jail\n");
fprintf(stderr, " -r <file>\treadonly files that should be staged\n");
fprintf(stderr, " -w <file>\twriteable files that should be staged\n");
- fprintf(stderr, " -p\t\tjail has /proc\t\n");
- fprintf(stderr, " -s\t\tjail has /sys\t\n");
- fprintf(stderr, " -l\t\tjail has /dev/log\t\n");
- fprintf(stderr, " -u\t\tjail has a ubus socket\t\n");
-
- return -1;
+ fprintf(stderr, " -d <num>\tshow debug log (increase num to increase verbosity)\n");
+ fprintf(stderr, " -p\t\tjail has /proc\n");
+ fprintf(stderr, " -s\t\tjail has /sys\n");
+ fprintf(stderr, " -l\t\tjail has /dev/log\n");
+ fprintf(stderr, " -u\t\tjail has a ubus socket\n");
+ fprintf(stderr, " -o\t\tremont jail root (/) read only\n");
+ fprintf(stderr, "\nWarning: by default root inside the jail is the same\n\
+and he has the same powers as root outside the jail,\n\
+thus he can escape the jail and/or break stuff.\n\
+Please use an appropriate seccomp filter (-S) to restrict his powers\n");
}
-static int child_running = 1;
-
-static void child_process_handler(struct uloop_process *c, int ret)
-{
- INFO("child (%d) exited: %d\n", c->pid, ret);
- uloop_end();
- child_running = 0;
-}
-
-struct uloop_process child_process = {
- .cb = child_process_handler,
-};
-
-static int spawn_child(void *arg)
+static int spawn_jail(void *arg)
{
- char *path = get_current_dir_name();
- int procfs = 0, sysfs = 0;
- char *seccomp = NULL;
- char **argv = arg;
- int argc = 0, ch;
- char *mpoint;
- int ronly = 0;
-
- while (argv[argc])
- argc++;
-
- optind = 0;
- while ((ch = getopt(argc, argv, OPT_ARGS)) != -1) {
- switch (ch) {
- case 'd':
- debug = 1;
- break;
- case 'S':
- seccomp = optarg;
- break;
- case 'p':
- procfs = 1;
- break;
- case 'o':
- ronly = 1;
- break;
- case 's':
- sysfs = 1;
- break;
- case 'n':
- if (sethostname(optarg, strlen(optarg)))
- ERROR("failed to sethostname: %s\n", strerror(errno));
- break;
- }
+ if (opts.name && sethostname(opts.name, strlen(opts.name))) {
+ ERROR("failed to sethostname: %s\n", strerror(errno));
}
- if (asprintf(&mpoint, "%s/old", path) < 0) {
- ERROR("failed to alloc pivot path: %s\n", strerror(errno));
- return -1;
- }
- mkdir_p(mpoint, 0755);
- if (pivot_root(path, mpoint) == -1) {
- ERROR("pivot_root failed:%s\n", strerror(errno));
- return -1;
- }
- free(mpoint);
- umount2("/old", MNT_DETACH);
- rmdir("/old");
- if (procfs) {
- mkdir("/proc", 0755);
- mount("proc", "/proc", "proc", MS_NOATIME, 0);
- }
- if (sysfs) {
- mkdir("/sys", 0755);
- mount("sysfs", "/sys", "sysfs", MS_NOATIME, 0);
+ if (build_jail_fs()) {
+ ERROR("failed to build jail fs");
+ exit(EXIT_FAILURE);
}
- if (ronly)
- mount(NULL, "/", NULL, MS_RDONLY | MS_REMOUNT, 0);
- uloop_init();
+ char **envp = build_envp(opts.seccomp);
+ if (!envp)
+ exit(EXIT_FAILURE);
- child_process.pid = spawn(path, &argv[optind], seccomp);
- uloop_process_add(&child_process);
- uloop_run();
- uloop_done();
- if (child_running) {
- kill(child_process.pid, SIGTERM);
- waitpid(child_process.pid, NULL, 0);
- }
+ //TODO: drop capabilities() here
+ //prctl(PR_CAPBSET_DROP, ..., 0, 0, 0);
- return 0;
+ INFO("exec-ing %s\n", *opts.jail_argv);
+ execve(*opts.jail_argv, opts.jail_argv, envp);
+ //we get there only if execve fails
+ ERROR("failed to execve %s: %s\n", *opts.jail_argv, strerror(errno));
+ exit(EXIT_FAILURE);
}
-static int namespace_running = 1;
+static int jail_running = 1;
+static int jail_return_code = 0;
-static void namespace_process_handler(struct uloop_process *c, int ret)
+static void jail_process_handler(struct uloop_process *c, int ret)
{
- INFO("namespace (%d) exited: %d\n", c->pid, ret);
+ if (WIFEXITED(ret)) {
+ jail_return_code = WEXITSTATUS(ret);
+ INFO("jail (%d) exited with exit: %d\n", c->pid, jail_return_code);
+ } else {
+ jail_return_code = WTERMSIG(ret);
+ INFO("jail (%d) exited with signal: %d\n", c->pid, jail_return_code);
+ }
+ jail_running = 0;
uloop_end();
- namespace_running = 0;
}
-struct uloop_process namespace_process = {
- .cb = namespace_process_handler,
+static struct uloop_process jail_process = {
+ .cb = jail_process_handler,
};
-static void spawn_namespace(const char *path, int argc, char **argv)
-{
- char *dir = get_current_dir_name();
-
- uloop_init();
- if (chdir(path)) {
- ERROR("failed to chdir() into the jail\n");
- return;
- }
- namespace_process.pid = clone(spawn_child,
- child_stack + STACK_SIZE,
- CLONE_NEWUTS | CLONE_NEWPID | CLONE_NEWNS | SIGCHLD, argv);
-
- if (namespace_process.pid != -1) {
- if (chdir(dir))
- ERROR("failed to chdir() out of the jail\n");
- free(dir);
- uloop_process_add(&namespace_process);
- uloop_run();
- uloop_done();
- if (namespace_running) {
- kill(namespace_process.pid, SIGTERM);
- waitpid(namespace_process.pid, NULL, 0);
- }
- } else {
- ERROR("failed to spawn namespace: %s\n", strerror(errno));
- }
-}
-
static void add_extra(char *name, int readonly)
{
struct extra *f;
@@ -419,16 +324,14 @@ static void add_extra(char *name, int readonly)
int main(int argc, char **argv)
{
uid_t uid = getuid();
- const char *name = NULL;
- char *path = NULL;
- struct stat s;
- int ch, ret;
char log[] = "/dev/log";
char ubus[] = "/var/run/ubus.sock";
+ int ret = EXIT_SUCCESS;
+ int ch;
if (uid) {
ERROR("not root, aborting: %s\n", strerror(errno));
- return -1;
+ return EXIT_FAILURE;
}
umask(022);
@@ -436,15 +339,27 @@ int main(int argc, char **argv)
while ((ch = getopt(argc, argv, OPT_ARGS)) != -1) {
switch (ch) {
case 'd':
- debug = 1;
+ debug = atoi(optarg);
+ break;
+ case 'p':
+ opts.procfs = 1;
+ break;
+ case 'o':
+ opts.ronly = 1;
+ break;
+ case 's':
+ opts.sysfs = 1;
+ break;
+ case 'S':
+ opts.seccomp = optarg;
+ add_extra(optarg, 1);
break;
case 'P':
- path = optarg;
+ opts.path = optarg;
break;
case 'n':
- name = optarg;
+ opts.name = optarg;
break;
- case 'S':
case 'r':
add_extra(optarg, 1);
break;
@@ -460,46 +375,52 @@ int main(int argc, char **argv)
}
}
- if (argc - optind < 1)
- return usage();
-
- if (!path && asprintf(&path, "/tmp/%s", basename(argv[optind])) == -1) {
- ERROR("failed to set root path\n: %s", strerror(errno));
- return -1;
+ //no <binary> param found
+ if (argc - optind < 1) {
+ usage();
+ return EXIT_FAILURE;
}
- if (!stat(path, &s)) {
- ERROR("%s already exists: %s\n", path, strerror(errno));
- return -1;
- }
+ opts.jail_argv = &argv[optind];
- if (name)
- prctl(PR_SET_NAME, name, NULL, NULL, NULL);
+ if (opts.name)
+ prctl(PR_SET_NAME, opts.name, NULL, NULL, NULL);
- avl_init(&libraries, avl_strcmp, false, NULL);
- alloc_library_path("/lib64");
- alloc_library_path("/lib");
- alloc_library_path("/usr/lib");
- load_ldso_conf("/etc/ld.so.conf");
-
- if (elf_load_deps(argv[optind])) {
- ERROR("failed to load dependencies\n");
- return -1;
+ if (!opts.path && asprintf(&opts.path, "/tmp/%s", basename(*opts.jail_argv)) == -1) {
+ ERROR("failed to asprintf root path: %s\n", strerror(errno));
+ return EXIT_FAILURE;
}
- if (elf_load_deps("libpreload-seccomp.so")) {
- ERROR("failed to load libpreload-seccomp.so\n");
- return -1;
+ if (mkdir(opts.path, 0755)) {
+ ERROR("unable to create root path: %s (%s)\n", opts.path, strerror(errno));
+ return EXIT_FAILURE;
}
- ret = build_jail(path);
+ uloop_init();
+ jail_process.pid = clone(spawn_jail,
+ child_stack + STACK_SIZE,
+ CLONE_NEWUTS | CLONE_NEWPID | CLONE_NEWNS | CLONE_NEWIPC | SIGCHLD, argv);
- if (!ret)
- spawn_namespace(path, argc, argv);
- else
- ERROR("failed to build jail\n");
+ if (jail_process.pid != -1) {
+ uloop_process_add(&jail_process);
+ uloop_run();
+ uloop_done();
+ if (jail_running) {
+ kill(jail_process.pid, SIGTERM);
+ waitpid(jail_process.pid, NULL, 0);
+ }
+ } else {
+ ERROR("failed to spawn namespace: %s\n", strerror(errno));
+ ret = EXIT_FAILURE;
+ }
- stop_jail(path);
+ if (rmdir(opts.path)) {
+ ERROR("Unable to remove root path: %s (%s)\n", opts.path, strerror(errno));
+ ret = EXIT_FAILURE;
+ }
- return ret;
+ if (ret)
+ return ret;
+
+ return jail_return_code;
}
generated by cgit v1.2.3 (git 2.25.1) at 2024-11-22 01:51:31 +0100