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: Christian Brauner christian.brauner@ubuntu.com --- /* Changelog */ v2: - make failure to create /dev/binderfs directory fatal in all circumstances - make tests run in user namespace to test whether binderfs can be mounted in user namespaces and so that unprivileged users can run the tests - use ksft_exit_skip()

v1: - check for ENODEV on mount failure to detect whether binderfs is available If it is not, skip the test and exit with success. --- tools/testing/selftests/Makefile | 1 + .../selftests/filesystems/binderfs/.gitignore | 1 + .../selftests/filesystems/binderfs/Makefile | 6 + .../filesystems/binderfs/binderfs_test.c | 270 ++++++++++++++++++ .../selftests/filesystems/binderfs/config | 3 + 5 files changed, 281 insertions(+) create mode 100644 tools/testing/selftests/filesystems/binderfs/.gitignore create mode 100644 tools/testing/selftests/filesystems/binderfs/Makefile create mode 100644 tools/testing/selftests/filesystems/binderfs/binderfs_test.c create mode 100644 tools/testing/selftests/filesystems/binderfs/config

diff --git a/tools/testing/selftests/Makefile b/tools/testing/selftests/Makefile index 1a2bd15c5b6e..400ee81a3043 100644 --- a/tools/testing/selftests/Makefile +++ b/tools/testing/selftests/Makefile @@ -10,6 +10,7 @@ TARGETS += drivers/dma-buf TARGETS += efivarfs TARGETS += exec TARGETS += filesystems +TARGETS += filesystems/binderfs TARGETS += firmware TARGETS += ftrace TARGETS += futex diff --git a/tools/testing/selftests/filesystems/binderfs/.gitignore b/tools/testing/selftests/filesystems/binderfs/.gitignore new file mode 100644 index 000000000000..8a5d9bf63dd4 --- /dev/null +++ b/tools/testing/selftests/filesystems/binderfs/.gitignore @@ -0,0 +1 @@ +binderfs_test diff --git a/tools/testing/selftests/filesystems/binderfs/Makefile b/tools/testing/selftests/filesystems/binderfs/Makefile new file mode 100644 index 000000000000..58cb659b56b4 --- /dev/null +++ b/tools/testing/selftests/filesystems/binderfs/Makefile @@ -0,0 +1,6 @@ +# SPDX-License-Identifier: GPL-2.0 + +CFLAGS += -I../../../../../usr/include/ +TEST_GEN_PROGS := binderfs_test + +include ../../lib.mk diff --git a/tools/testing/selftests/filesystems/binderfs/binderfs_test.c b/tools/testing/selftests/filesystems/binderfs/binderfs_test.c new file mode 100644 index 000000000000..988f54f2d3b0 --- /dev/null +++ b/tools/testing/selftests/filesystems/binderfs/binderfs_test.c @@ -0,0 +1,270 @@ +// 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; + + ksft_exit_fail_msg("%s - Failed to write to file %s\n", strerror(errno), + 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)); + } + + printf("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)); + } + + printf("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(); +} diff --git a/tools/testing/selftests/filesystems/binderfs/config b/tools/testing/selftests/filesystems/binderfs/config new file mode 100644 index 000000000000..02dd6cc9cf99 --- /dev/null +++ b/tools/testing/selftests/filesystems/binderfs/config @@ -0,0 +1,3 @@ +CONFIG_ANDROID=y +CONFIG_ANDROID_BINDERFS=y +CONFIG_ANDROID_BINDER_IPC=y