1// SPDX-License-Identifier: GPL-2.0
  2
  3#define _GNU_SOURCE
  4#include <errno.h>
  5#include <fcntl.h>
  6#include <pthread.h>
  7#include <sched.h>
  8#include <stdbool.h>
  9#include <stdio.h>
 10#include <stdlib.h>
 11#include <string.h>
 12#include <sys/fsuid.h>
 13#include <sys/ioctl.h>
 14#include <sys/mount.h>
 15#include <sys/socket.h>
 16#include <sys/stat.h>
 17#include <sys/sysinfo.h>
 18#include <sys/types.h>
 19#include <sys/wait.h>
 20#include <unistd.h>
 21#include <linux/android/binder.h>
 22#include <linux/android/binderfs.h>
 23
 24#include "../../kselftest_harness.h"
 25
 26#define DEFAULT_THREADS 4
 27
 28#define PTR_TO_INT(p) ((int)((intptr_t)(p)))
 29#define INT_TO_PTR(u) ((void *)((intptr_t)(u)))
 30
 31#define close_prot_errno_disarm(fd) \
 32	if (fd >= 0) {              \
 33		int _e_ = errno;    \
 34		close(fd);          \
 35		errno = _e_;        \
 36		fd = -EBADF;        \
 37	}
 38
 39static void change_mountns(struct __test_metadata *_metadata)
 40{
 41	int ret;
 42
 43	ret = unshare(CLONE_NEWNS);
 44	ASSERT_EQ(ret, 0) {
 45		TH_LOG("%s - Failed to unshare mount namespace",
 46			strerror(errno));
 47	}
 48
 49	ret = mount(NULL, "/", NULL, MS_REC | MS_PRIVATE, 0);
 50	ASSERT_EQ(ret, 0) {
 51		TH_LOG("%s - Failed to mount / as private",
 52			strerror(errno));
 53	}
 54}
 55
 56static int __do_binderfs_test(struct __test_metadata *_metadata)
 57{
 58	int fd, ret, saved_errno, result = 1;
 59	size_t len;
 60	ssize_t wret;
 61	struct binderfs_device device = { 0 };
 62	struct binder_version version = { 0 };
 63	char binderfs_mntpt[] = P_tmpdir "/binderfs_XXXXXX",
 64		device_path[sizeof(P_tmpdir "/binderfs_XXXXXX/") + BINDERFS_MAX_NAME];
 65
 66	change_mountns(_metadata);
 67
 68	EXPECT_NE(mkdtemp(binderfs_mntpt), NULL) {
 69		TH_LOG("%s - Failed to create binderfs mountpoint",
 70			strerror(errno));
 71		goto out;
 72	}
 73
 74	ret = mount(NULL, binderfs_mntpt, "binder", 0, 0);
 75	EXPECT_EQ(ret, 0) {
 76		if (errno == ENODEV)
 77			XFAIL(goto out, "binderfs missing");
 78		TH_LOG("%s - Failed to mount binderfs", strerror(errno));
 79		goto rmdir;
 80	}
 81
 82	/* success: binderfs mounted */
 83
 84	memcpy(device.name, "my-binder", strlen("my-binder"));
 85
 86	snprintf(device_path, sizeof(device_path), "%s/binder-control", binderfs_mntpt);
 87	fd = open(device_path, O_RDONLY | O_CLOEXEC);
 88	EXPECT_GE(fd, 0) {
 89		TH_LOG("%s - Failed to open binder-control device",
 90			strerror(errno));
 91		goto umount;
 92	}
 93
 94	ret = ioctl(fd, BINDER_CTL_ADD, &device);
 95	saved_errno = errno;
 96	close(fd);
 97	errno = saved_errno;
 98	EXPECT_GE(ret, 0) {
 99		TH_LOG("%s - Failed to allocate new binder device",
100			strerror(errno));
101		goto umount;
102	}
103
104	TH_LOG("Allocated new binder device with major %d, minor %d, and name %s",
105		device.major, device.minor, device.name);
106
107	/* success: binder device allocation */
108
109	snprintf(device_path, sizeof(device_path), "%s/my-binder", binderfs_mntpt);
110	fd = open(device_path, O_CLOEXEC | O_RDONLY);
111	EXPECT_GE(fd, 0) {
112		TH_LOG("%s - Failed to open my-binder device",
113			strerror(errno));
114		goto umount;
115	}
116
117	ret = ioctl(fd, BINDER_VERSION, &version);
118	saved_errno = errno;
119	close(fd);
120	errno = saved_errno;
121	EXPECT_GE(ret, 0) {
122		TH_LOG("%s - Failed to open perform BINDER_VERSION request",
123			strerror(errno));
124		goto umount;
125	}
126
127	TH_LOG("Detected binder version: %d", version.protocol_version);
128
129	/* success: binder transaction with binderfs binder device */
130
131	ret = unlink(device_path);
132	EXPECT_EQ(ret, 0) {
133		TH_LOG("%s - Failed to delete binder device",
134			strerror(errno));
135		goto umount;
136	}
137
138	/* success: binder device removal */
139
140	snprintf(device_path, sizeof(device_path), "%s/binder-control", binderfs_mntpt);
141	ret = unlink(device_path);
142	EXPECT_NE(ret, 0) {
143		TH_LOG("Managed to delete binder-control device");
144		goto umount;
145	}
146	EXPECT_EQ(errno, EPERM) {
147		TH_LOG("%s - Failed to delete binder-control device but exited with unexpected error code",
148			strerror(errno));
149		goto umount;
150	}
151
152	/* success: binder-control device removal failed as expected */
153	result = 0;
154
155umount:
156	ret = umount2(binderfs_mntpt, MNT_DETACH);
157	EXPECT_EQ(ret, 0) {
158		TH_LOG("%s - Failed to unmount binderfs", strerror(errno));
159	}
160rmdir:
161	ret = rmdir(binderfs_mntpt);
162	EXPECT_EQ(ret, 0) {
163		TH_LOG("%s - Failed to rmdir binderfs mount", strerror(errno));
164	}
165out:
166	return result;
167}
168
169static int wait_for_pid(pid_t pid)
170{
171	int status, ret;
172
173again:
174	ret = waitpid(pid, &status, 0);
175	if (ret == -1) {
176		if (errno == EINTR)
177			goto again;
178
179		return -1;
180	}
181
182	if (!WIFEXITED(status))
183		return -1;
184
185	return WEXITSTATUS(status);
186}
187
188static int setid_userns_root(void)
189{
190	if (setuid(0))
191		return -1;
192	if (setgid(0))
193		return -1;
194
195	setfsuid(0);
196	setfsgid(0);
197
198	return 0;
199}
200
201enum idmap_type {
202	UID_MAP,
203	GID_MAP,
204};
205
206static ssize_t read_nointr(int fd, void *buf, size_t count)
207{
208	ssize_t ret;
209again:
210	ret = read(fd, buf, count);
211	if (ret < 0 && errno == EINTR)
212		goto again;
213
214	return ret;
215}
216
217static ssize_t write_nointr(int fd, const void *buf, size_t count)
218{
219	ssize_t ret;
220again:
221	ret = write(fd, buf, count);
222	if (ret < 0 && errno == EINTR)
223		goto again;
224
225	return ret;
226}
227
228static int write_id_mapping(enum idmap_type type, pid_t pid, const char *buf,
229			    size_t buf_size)
230{
231	int fd;
232	int ret;
233	char path[4096];
234
235	if (type == GID_MAP) {
236		int setgroups_fd;
237
238		snprintf(path, sizeof(path), "/proc/%d/setgroups", pid);
239		setgroups_fd = open(path, O_WRONLY | O_CLOEXEC | O_NOFOLLOW);
240		if (setgroups_fd < 0 && errno != ENOENT)
241			return -1;
242
243		if (setgroups_fd >= 0) {
244			ret = write_nointr(setgroups_fd, "deny", sizeof("deny") - 1);
245			close_prot_errno_disarm(setgroups_fd);
246			if (ret != sizeof("deny") - 1)
247				return -1;
248		}
249	}
250
251	switch (type) {
252	case UID_MAP:
253		ret = snprintf(path, sizeof(path), "/proc/%d/uid_map", pid);
254		break;
255	case GID_MAP:
256		ret = snprintf(path, sizeof(path), "/proc/%d/gid_map", pid);
257		break;
258	default:
259		return -1;
260	}
261	if (ret < 0 || ret >= sizeof(path))
262		return -E2BIG;
263
264	fd = open(path, O_WRONLY | O_CLOEXEC | O_NOFOLLOW);
265	if (fd < 0)
266		return -1;
267
268	ret = write_nointr(fd, buf, buf_size);
269	close_prot_errno_disarm(fd);
270	if (ret != buf_size)
271		return -1;
272
273	return 0;
274}
275
276static void change_userns(struct __test_metadata *_metadata, int syncfds[2])
277{
278	int ret;
279	char buf;
280
281	close_prot_errno_disarm(syncfds[1]);
282
283	ret = unshare(CLONE_NEWUSER);
284	ASSERT_EQ(ret, 0) {
285		TH_LOG("%s - Failed to unshare user namespace",
286			strerror(errno));
287	}
288
289	ret = write_nointr(syncfds[0], "1", 1);
290	ASSERT_EQ(ret, 1) {
291		TH_LOG("write_nointr() failed");
292	}
293
294	ret = read_nointr(syncfds[0], &buf, 1);
295	ASSERT_EQ(ret, 1) {
296		TH_LOG("read_nointr() failed");
297	}
298
299	close_prot_errno_disarm(syncfds[0]);
300
301	ASSERT_EQ(setid_userns_root(), 0) {
302		TH_LOG("setid_userns_root() failed");
303	}
304}
305
306static void change_idmaps(struct __test_metadata *_metadata, int syncfds[2], pid_t pid)
307{
308	int ret;
309	char buf;
310	char id_map[4096];
311
312	close_prot_errno_disarm(syncfds[0]);
313
314	ret = read_nointr(syncfds[1], &buf, 1);
315	ASSERT_EQ(ret, 1) {
316		TH_LOG("read_nointr() failed");
317	}
318
319	snprintf(id_map, sizeof(id_map), "0 %d 1\n", getuid());
320	ret = write_id_mapping(UID_MAP, pid, id_map, strlen(id_map));
321	ASSERT_EQ(ret, 0) {
322		TH_LOG("write_id_mapping(UID_MAP) failed");
323	}
324
325	snprintf(id_map, sizeof(id_map), "0 %d 1\n", getgid());
326	ret = write_id_mapping(GID_MAP, pid, id_map, strlen(id_map));
327	ASSERT_EQ(ret, 0) {
328		TH_LOG("write_id_mapping(GID_MAP) failed");
329	}
330
331	ret = write_nointr(syncfds[1], "1", 1);
332	ASSERT_EQ(ret, 1) {
333		TH_LOG("write_nointr() failed");
334	}
335
336	close_prot_errno_disarm(syncfds[1]);
337}
338
339struct __test_metadata *_thread_metadata;
340static void *binder_version_thread(void *data)
341{
342	struct __test_metadata *_metadata = _thread_metadata;
343	int fd = PTR_TO_INT(data);
344	struct binder_version version = { 0 };
345	int ret;
346
347	ret = ioctl(fd, BINDER_VERSION, &version);
348	if (ret < 0)
349		TH_LOG("%s - Failed to open perform BINDER_VERSION request\n",
350			strerror(errno));
351
352	pthread_exit(data);
353}
354
355/*
356 * Regression test:
357 * 2669b8b0c798 ("binder: prevent UAF for binderfs devices")
358 * f0fe2c0f050d ("binder: prevent UAF for binderfs devices II")
359 * 211b64e4b5b6 ("binderfs: use refcount for binder control devices too")
360 */
361TEST(binderfs_stress)
362{
363	int fds[1000];
364	int syncfds[2];
365	pid_t pid;
366	int fd, ret;
367	size_t len;
368	struct binderfs_device device = { 0 };
369	char binderfs_mntpt[] = P_tmpdir "/binderfs_XXXXXX",
370		device_path[sizeof(P_tmpdir "/binderfs_XXXXXX/") + BINDERFS_MAX_NAME];
371
372	ret = socketpair(PF_LOCAL, SOCK_STREAM | SOCK_CLOEXEC, 0, syncfds);
373	ASSERT_EQ(ret, 0) {
374		TH_LOG("%s - Failed to create socket pair", strerror(errno));
375	}
376
377	pid = fork();
378	ASSERT_GE(pid, 0) {
379		TH_LOG("%s - Failed to fork", strerror(errno));
380		close_prot_errno_disarm(syncfds[0]);
381		close_prot_errno_disarm(syncfds[1]);
382	}
383
384	if (pid == 0) {
385		int i, j, k, nthreads;
386		pthread_attr_t attr;
387		pthread_t threads[DEFAULT_THREADS];
388		change_userns(_metadata, syncfds);
389		change_mountns(_metadata);
390
391		ASSERT_NE(mkdtemp(binderfs_mntpt), NULL) {
392			TH_LOG("%s - Failed to create binderfs mountpoint",
393				strerror(errno));
394		}
395
396		ret = mount(NULL, binderfs_mntpt, "binder", 0, 0);
397		ASSERT_EQ(ret, 0) {
398			TH_LOG("%s - Failed to mount binderfs", strerror(errno));
399		}
400
401		for (int i = 0; i < ARRAY_SIZE(fds); i++) {
402
403			snprintf(device_path, sizeof(device_path),
404				 "%s/binder-control", binderfs_mntpt);
405			fd = open(device_path, O_RDONLY | O_CLOEXEC);
406			ASSERT_GE(fd, 0) {
407				TH_LOG("%s - Failed to open binder-control device",
408					strerror(errno));
409			}
410
411			memset(&device, 0, sizeof(device));
412			snprintf(device.name, sizeof(device.name), "%d", i);
413			ret = ioctl(fd, BINDER_CTL_ADD, &device);
414			close_prot_errno_disarm(fd);
415			ASSERT_EQ(ret, 0) {
416				TH_LOG("%s - Failed to allocate new binder device",
417					strerror(errno));
418			}
419
420			snprintf(device_path, sizeof(device_path), "%s/%d",
421				 binderfs_mntpt, i);
422			fds[i] = open(device_path, O_RDONLY | O_CLOEXEC);
423			ASSERT_GE(fds[i], 0) {
424				TH_LOG("%s - Failed to open binder device", strerror(errno));
425			}
426		}
427
428		ret = umount2(binderfs_mntpt, MNT_DETACH);
429		ASSERT_EQ(ret, 0) {
430			TH_LOG("%s - Failed to unmount binderfs", strerror(errno));
431			rmdir(binderfs_mntpt);
432		}
433
434		nthreads = get_nprocs_conf();
435		if (nthreads > DEFAULT_THREADS)
436			nthreads = DEFAULT_THREADS;
437
438		_thread_metadata = _metadata;
439		pthread_attr_init(&attr);
440		for (k = 0; k < ARRAY_SIZE(fds); k++) {
441			for (i = 0; i < nthreads; i++) {
442				ret = pthread_create(&threads[i], &attr, binder_version_thread, INT_TO_PTR(fds[k]));
443				if (ret) {
444					TH_LOG("%s - Failed to create thread %d",
445						strerror(errno), i);
446					break;
447				}
448			}
449
450			for (j = 0; j < i; j++) {
451				void *fdptr = NULL;
452
453				ret = pthread_join(threads[j], &fdptr);
454				if (ret)
455					TH_LOG("%s - Failed to join thread %d for fd %d",
456						strerror(errno), j, PTR_TO_INT(fdptr));
457			}
458		}
459		pthread_attr_destroy(&attr);
460
461		for (k = 0; k < ARRAY_SIZE(fds); k++)
462			close(fds[k]);
463
464		exit(EXIT_SUCCESS);
465	}
466
467	change_idmaps(_metadata, syncfds, pid);
468
469	ret = wait_for_pid(pid);
470	ASSERT_EQ(ret, 0) {
471		TH_LOG("wait_for_pid() failed");
472	}
473}
474
475TEST(binderfs_test_privileged)
476{
477	if (geteuid() != 0)
478		XFAIL(return, "Tests are not run as root. Skipping privileged tests");
479
480	if (__do_binderfs_test(_metadata))
481		XFAIL(return, "The Android binderfs filesystem is not available");
482}
483
484TEST(binderfs_test_unprivileged)
485{
486	int ret;
487	int syncfds[2];
488	pid_t pid;
489
490	ret = socketpair(PF_LOCAL, SOCK_STREAM | SOCK_CLOEXEC, 0, syncfds);
491	ASSERT_EQ(ret, 0) {
492		TH_LOG("%s - Failed to create socket pair", strerror(errno));
493	}
494
495	pid = fork();
496	ASSERT_GE(pid, 0) {
497		close_prot_errno_disarm(syncfds[0]);
498		close_prot_errno_disarm(syncfds[1]);
499		TH_LOG("%s - Failed to fork", strerror(errno));
500	}
501
502	if (pid == 0) {
503		change_userns(_metadata, syncfds);
504		if (__do_binderfs_test(_metadata))
505			exit(2);
506		exit(EXIT_SUCCESS);
507	}
508
509	change_idmaps(_metadata, syncfds, pid);
510
511	ret = wait_for_pid(pid);
512	if (ret) {
513		if (ret == 2)
514			XFAIL(return, "The Android binderfs filesystem is not available");
515		ASSERT_EQ(ret, 0) {
516			TH_LOG("wait_for_pid() failed");
517		}
518	}
519}
520
521TEST_HARNESS_MAIN