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Commit 75abec73 authored by Christian Brauner's avatar Christian Brauner Committed by Greg Kroah-Hartman
Browse files

selftests: add binderfs selftests 



This adds the promised selftest for binderfs. It will verify the following
things:
- binderfs mounting works
- binder device allocation works
- performing a binder ioctl() request through a binderfs device works
- binder device removal works
- binder-control removal fails
- binderfs unmounting works

The tests are performed both privileged and unprivileged. The latter
verifies that binderfs behaves correctly in user namespaces.

Cc: Todd Kjos <tkjos@google.com>
Signed-off-by: default avatarChristian Brauner <christian.brauner@ubuntu.com>
Acked-by: default avatarShuah Khan <shuah@kernel.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent f17b5f06

tools/testing/selftests/Makefile

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Original line number Diff line number Diff line
@@ -10,6 +10,7 @@ TARGETS += drivers/dma-buf 
TARGETS += efivarfs

TARGETS += exec

TARGETS += filesystems

TARGETS += filesystems/binderfs

TARGETS += firmware

TARGETS += ftrace

TARGETS += futex

tools/testing/selftests/filesystems/binderfs/.gitignore

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binderfs_test

tools/testing/selftests/filesystems/binderfs/Makefile

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# SPDX-License-Identifier: GPL-2.0



CFLAGS += -I../../../../../usr/include/

TEST_GEN_PROGS := binderfs_test



include ../../lib.mk

tools/testing/selftests/filesystems/binderfs/binderfs_test.c

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// SPDX-License-Identifier: GPL-2.0



#define _GNU_SOURCE

#include <errno.h>

#include <fcntl.h>

#include <sched.h>

#include <stdbool.h>

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include <sys/ioctl.h>

#include <sys/mount.h>

#include <sys/stat.h>

#include <sys/types.h>

#include <unistd.h>

#include <linux/android/binder.h>

#include <linux/android/binderfs.h>

#include "../../kselftest.h"



static ssize_t write_nointr(int fd, const void *buf, size_t count)

{

	ssize_t ret;

again:

	ret = write(fd, buf, count);

	if (ret < 0 && errno == EINTR)

		goto again;



	return ret;

}



static void write_to_file(const char *filename, const void *buf, size_t count,

			  int allowed_errno)

{

	int fd, saved_errno;

	ssize_t ret;



	fd = open(filename, O_WRONLY | O_CLOEXEC);

	if (fd < 0)

		ksft_exit_fail_msg("%s - Failed to open file %s\n",

				   strerror(errno), filename);



	ret = write_nointr(fd, buf, count);

	if (ret < 0) {

		if (allowed_errno && (errno == allowed_errno)) {

			close(fd);

			return;

		}



		goto on_error;

	}



	if ((size_t)ret != count)

		goto on_error;



	close(fd);

	return;



on_error:

	saved_errno = errno;

	close(fd);

	errno = saved_errno;



	if (ret < 0)

		ksft_exit_fail_msg("%s - Failed to write to file %s\n",

				   strerror(errno), filename);



	ksft_exit_fail_msg("Failed to write to file %s\n", filename);

}



static void change_to_userns(void)

{

	int ret;

	uid_t uid;

	gid_t gid;

	/* {g,u}id_map files only allow a max of 4096 bytes written to them */

	char idmap[4096];



	uid = getuid();

	gid = getgid();



	ret = unshare(CLONE_NEWUSER);

	if (ret < 0)

		ksft_exit_fail_msg("%s - Failed to unshare user namespace\n",

				   strerror(errno));



	write_to_file("/proc/self/setgroups", "deny", strlen("deny"), ENOENT);



	ret = snprintf(idmap, sizeof(idmap), "0 %d 1", uid);

	if (ret < 0 || (size_t)ret >= sizeof(idmap))

		ksft_exit_fail_msg("%s - Failed to prepare uid mapping\n",

				   strerror(errno));



	write_to_file("/proc/self/uid_map", idmap, strlen(idmap), 0);



	ret = snprintf(idmap, sizeof(idmap), "0 %d 1", gid);

	if (ret < 0 || (size_t)ret >= sizeof(idmap))

		ksft_exit_fail_msg("%s - Failed to prepare uid mapping\n",

				   strerror(errno));



	write_to_file("/proc/self/gid_map", idmap, strlen(idmap), 0);



	ret = setgid(0);

	if (ret)

		ksft_exit_fail_msg("%s - Failed to setgid(0)\n",

				   strerror(errno));



	ret = setuid(0);

	if (ret)

		ksft_exit_fail_msg("%s - Failed to setgid(0)\n",

				   strerror(errno));

}



static void change_to_mountns(void)

{

	int ret;



	ret = unshare(CLONE_NEWNS);

	if (ret < 0)

		ksft_exit_fail_msg("%s - Failed to unshare mount namespace\n",

				   strerror(errno));



	ret = mount(NULL, "/", NULL, MS_REC | MS_PRIVATE, 0);

	if (ret < 0)

		ksft_exit_fail_msg("%s - Failed to mount / as private\n",

				   strerror(errno));

}



static void rmdir_protect_errno(const char *dir)

{

	int saved_errno = errno;

	(void)rmdir(dir);

	errno = saved_errno;

}



static void __do_binderfs_test(void)

{

	int fd, ret, saved_errno;

	size_t len;

	ssize_t wret;

	bool keep = false;

	struct binderfs_device device = { 0 };

	struct binder_version version = { 0 };



	change_to_mountns();



	ret = mkdir("/dev/binderfs", 0755);

	if (ret < 0) {

		if (errno != EEXIST)

			ksft_exit_fail_msg(

				"%s - Failed to create binderfs mountpoint\n",

				strerror(errno));



		keep = true;

	}



	ret = mount(NULL, "/dev/binderfs", "binder", 0, 0);

	if (ret < 0) {

		if (errno != ENODEV)

			ksft_exit_fail_msg("%s - Failed to mount binderfs\n",

					   strerror(errno));



		keep ? : rmdir_protect_errno("/dev/binderfs");

		ksft_exit_skip(

			"The Android binderfs filesystem is not available\n");

	}



	/* binderfs mount test passed */

	ksft_inc_pass_cnt();



	memcpy(device.name, "my-binder", strlen("my-binder"));



	fd = open("/dev/binderfs/binder-control", O_RDONLY | O_CLOEXEC);

	if (fd < 0)

		ksft_exit_fail_msg(

			"%s - Failed to open binder-control device\n",

			strerror(errno));



	ret = ioctl(fd, BINDER_CTL_ADD, &device);

	saved_errno = errno;

	close(fd);

	errno = saved_errno;

	if (ret < 0) {

		keep ? : rmdir_protect_errno("/dev/binderfs");

		ksft_exit_fail_msg(

			"%s - Failed to allocate new binder device\n",

			strerror(errno));

	}



	ksft_print_msg(

		"Allocated new binder device with major %d, minor %d, and name %s\n",

		device.major, device.minor, device.name);



	/* binder device allocation test passed */

	ksft_inc_pass_cnt();



	fd = open("/dev/binderfs/my-binder", O_CLOEXEC | O_RDONLY);

	if (fd < 0) {

		keep ? : rmdir_protect_errno("/dev/binderfs");

		ksft_exit_fail_msg("%s - Failed to open my-binder device\n",

				   strerror(errno));

	}



	ret = ioctl(fd, BINDER_VERSION, &version);

	saved_errno = errno;

	close(fd);

	errno = saved_errno;

	if (ret < 0) {

		keep ? : rmdir_protect_errno("/dev/binderfs");

		ksft_exit_fail_msg(

			"%s - Failed to open perform BINDER_VERSION request\n",

			strerror(errno));

	}



	ksft_print_msg("Detected binder version: %d\n",

		       version.protocol_version);



	/* binder transaction with binderfs binder device passed */

	ksft_inc_pass_cnt();



	ret = unlink("/dev/binderfs/my-binder");

	if (ret < 0) {

		keep ? : rmdir_protect_errno("/dev/binderfs");

		ksft_exit_fail_msg("%s - Failed to delete binder device\n",

				   strerror(errno));

	}



	/* binder device removal passed */

	ksft_inc_pass_cnt();



	ret = unlink("/dev/binderfs/binder-control");

	if (!ret) {

		keep ? : rmdir_protect_errno("/dev/binderfs");

		ksft_exit_fail_msg("Managed to delete binder-control device\n");

	} else if (errno != EPERM) {

		keep ? : rmdir_protect_errno("/dev/binderfs");

		ksft_exit_fail_msg(

			"%s - Failed to delete binder-control device but exited with unexpected error code\n",

			strerror(errno));

	}



	/* binder-control device removal failed as expected */

	ksft_inc_xfail_cnt();



on_error:

	ret = umount2("/dev/binderfs", MNT_DETACH);

	keep ?: rmdir_protect_errno("/dev/binderfs");

	if (ret < 0)

		ksft_exit_fail_msg("%s - Failed to unmount binderfs\n",

				   strerror(errno));



	/* binderfs unmount test passed */

	ksft_inc_pass_cnt();

}



static void binderfs_test_privileged()

{

	if (geteuid() != 0)

		ksft_print_msg(

			"Tests are not run as root. Skipping privileged tests\n");

	else

		__do_binderfs_test();

}



static void binderfs_test_unprivileged()

{

	change_to_userns();

	__do_binderfs_test();

}



int main(int argc, char *argv[])

{

	binderfs_test_privileged();

	binderfs_test_unprivileged();

	ksft_exit_pass();

}

tools/testing/selftests/filesystems/binderfs/config

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CONFIG_ANDROID=y

CONFIG_ANDROID_BINDERFS=y

CONFIG_ANDROID_BINDER_IPC=y