Exercises Landlock's IOCTL feature in different combinations of handling and permitting the LANDLOCK_ACCESS_FS_IOCTL_DEV right, and in different combinations of using files and directories. Signed-off-by: Günther Noack <gnoack@xxxxxxxxxx> --- tools/testing/selftests/landlock/fs_test.c | 227 ++++++++++++++++++++- 1 file changed, 224 insertions(+), 3 deletions(-) diff --git a/tools/testing/selftests/landlock/fs_test.c b/tools/testing/selftests/landlock/fs_test.c index 418ad745a5dd..8a72e26d4977 100644 --- a/tools/testing/selftests/landlock/fs_test.c +++ b/tools/testing/selftests/landlock/fs_test.c @@ -8,6 +8,7 @@ */ #define _GNU_SOURCE +#include <asm/termbits.h> #include <fcntl.h> #include <linux/landlock.h> #include <linux/magic.h> @@ -15,6 +16,7 @@ #include <stdio.h> #include <string.h> #include <sys/capability.h> +#include <sys/ioctl.h> #include <sys/mount.h> #include <sys/prctl.h> #include <sys/sendfile.h> @@ -23,6 +25,12 @@ #include <sys/vfs.h> #include <unistd.h> +/* + * Intentionally included last to work around header conflict. + * See https://sourceware.org/glibc/wiki/Synchronizing_Headers. + */ +#include <linux/fs.h> + #include "common.h" #ifndef renameat2 @@ -737,6 +745,9 @@ static int create_ruleset(struct __test_metadata *const _metadata, } for (i = 0; rules[i].path; i++) { + if (!rules[i].access) + continue; + add_path_beneath(_metadata, ruleset_fd, rules[i].access, rules[i].path); } @@ -3445,7 +3456,7 @@ TEST_F_FORK(layout1, truncate_unhandled) LANDLOCK_ACCESS_FS_WRITE_FILE; int ruleset_fd; - /* Enable Landlock. */ + /* Enables Landlock. */ ruleset_fd = create_ruleset(_metadata, handled, rules); ASSERT_LE(0, ruleset_fd); @@ -3528,7 +3539,7 @@ TEST_F_FORK(layout1, truncate) LANDLOCK_ACCESS_FS_TRUNCATE; int ruleset_fd; - /* Enable Landlock. */ + /* Enables Landlock. */ ruleset_fd = create_ruleset(_metadata, handled, rules); ASSERT_LE(0, ruleset_fd); @@ -3754,7 +3765,7 @@ TEST_F_FORK(ftruncate, open_and_ftruncate) }; int fd, ruleset_fd; - /* Enable Landlock. */ + /* Enables Landlock. */ ruleset_fd = create_ruleset(_metadata, variant->handled, rules); ASSERT_LE(0, ruleset_fd); enforce_ruleset(_metadata, ruleset_fd); @@ -3831,6 +3842,16 @@ TEST_F_FORK(ftruncate, open_and_ftruncate_in_different_processes) ASSERT_EQ(0, close(socket_fds[1])); } +/* Invokes the FS_IOC_GETFLAGS IOCTL and returns its errno or 0. */ +static int test_fs_ioc_getflags_ioctl(int fd) +{ + uint32_t flags; + + if (ioctl(fd, FS_IOC_GETFLAGS, &flags) < 0) + return errno; + return 0; +} + TEST(memfd_ftruncate) { int fd; @@ -3847,6 +3868,206 @@ TEST(memfd_ftruncate) ASSERT_EQ(0, close(fd)); } +static int test_fionread_ioctl(int fd) +{ + size_t sz = 0; + + if (ioctl(fd, FIONREAD, &sz) < 0 && errno == EACCES) + return errno; + return 0; +} + +/* clang-format off */ +FIXTURE(ioctl) {}; + +FIXTURE_SETUP(ioctl) {}; + +FIXTURE_TEARDOWN(ioctl) {}; +/* clang-format on */ + +FIXTURE_VARIANT(ioctl) +{ + const __u64 handled; + const __u64 allowed; + const mode_t open_mode; + /* + * TCGETS is used as a characteristic device-specific IOCTL command. + * The logic is the same for other IOCTL commands as well. + */ + const int expected_tcgets_result; /* terminal device IOCTL */ + /* + * FIONREAD is implemented in fs/ioctl.c for regular files, + * but we do not blanket-permit it for devices. + */ + const int expected_fionread_result; +}; + +/* clang-format off */ +FIXTURE_VARIANT_ADD(ioctl, handled_i_allowed_none) { + /* clang-format on */ + .handled = LANDLOCK_ACCESS_FS_IOCTL_DEV, + .allowed = 0, + .open_mode = O_RDWR, + .expected_tcgets_result = EACCES, + .expected_fionread_result = EACCES, +}; + +/* clang-format off */ +FIXTURE_VARIANT_ADD(ioctl, handled_i_allowed_i) { + /* clang-format on */ + .handled = LANDLOCK_ACCESS_FS_IOCTL_DEV, + .allowed = LANDLOCK_ACCESS_FS_IOCTL_DEV, + .open_mode = O_RDWR, + .expected_tcgets_result = 0, + .expected_fionread_result = 0, +}; + +/* clang-format off */ +FIXTURE_VARIANT_ADD(ioctl, unhandled) { + /* clang-format on */ + .handled = LANDLOCK_ACCESS_FS_EXECUTE, + .allowed = LANDLOCK_ACCESS_FS_EXECUTE, + .open_mode = O_RDWR, + .expected_tcgets_result = 0, + .expected_fionread_result = 0, +}; + +static int test_tcgets_ioctl(int fd) +{ + struct termios info; + + if (ioctl(fd, TCGETS, &info) < 0) + return errno; + return 0; +} + +TEST_F_FORK(ioctl, handle_dir_access_file) +{ + const int flag = 0; + const struct rule rules[] = { + { + .path = "/dev", + .access = variant->allowed, + }, + {}, + }; + int file_fd, ruleset_fd; + + /* Enables Landlock. */ + ruleset_fd = create_ruleset(_metadata, variant->handled, rules); + ASSERT_LE(0, ruleset_fd); + enforce_ruleset(_metadata, ruleset_fd); + ASSERT_EQ(0, close(ruleset_fd)); + + file_fd = open("/dev/tty", variant->open_mode); + ASSERT_LE(0, file_fd); + + /* Checks that IOCTL commands return the expected errors. */ + EXPECT_EQ(variant->expected_tcgets_result, test_tcgets_ioctl(file_fd)); + EXPECT_EQ(variant->expected_fionread_result, + test_fionread_ioctl(file_fd)); + + /* Checks that unrestrictable commands are unrestricted. */ + EXPECT_EQ(0, ioctl(file_fd, FIOCLEX)); + EXPECT_EQ(0, ioctl(file_fd, FIONCLEX)); + EXPECT_EQ(0, ioctl(file_fd, FIONBIO, &flag)); + EXPECT_EQ(0, ioctl(file_fd, FIOASYNC, &flag)); + EXPECT_EQ(0, ioctl(file_fd, FIGETBSZ, &flag)); + + ASSERT_EQ(0, close(file_fd)); +} + +TEST_F_FORK(ioctl, handle_dir_access_dir) +{ + const int flag = 0; + const struct rule rules[] = { + { + .path = "/dev", + .access = variant->allowed, + }, + {}, + }; + int dir_fd, ruleset_fd; + + /* Enables Landlock. */ + ruleset_fd = create_ruleset(_metadata, variant->handled, rules); + ASSERT_LE(0, ruleset_fd); + enforce_ruleset(_metadata, ruleset_fd); + ASSERT_EQ(0, close(ruleset_fd)); + + /* + * Ignore variant->open_mode for this test, as we intend to open a + * directory. If the directory can not be opened, the variant is + * infeasible to test with an opened directory. + */ + dir_fd = open("/dev", O_RDONLY); + if (dir_fd < 0) + return; + + /* + * Checks that IOCTL commands return the expected errors. + * We do not use the expected values from the fixture here. + * + * When using IOCTL on a directory, no Landlock restrictions apply. + * TCGETS will fail anyway because it is not invoked on a TTY device. + */ + EXPECT_EQ(ENOTTY, test_tcgets_ioctl(dir_fd)); + EXPECT_EQ(0, test_fionread_ioctl(dir_fd)); + + /* Checks that unrestrictable commands are unrestricted. */ + EXPECT_EQ(0, ioctl(dir_fd, FIOCLEX)); + EXPECT_EQ(0, ioctl(dir_fd, FIONCLEX)); + EXPECT_EQ(0, ioctl(dir_fd, FIONBIO, &flag)); + EXPECT_EQ(0, ioctl(dir_fd, FIOASYNC, &flag)); + EXPECT_EQ(0, ioctl(dir_fd, FIGETBSZ, &flag)); + + ASSERT_EQ(0, close(dir_fd)); +} + +TEST_F_FORK(ioctl, handle_file_access_file) +{ + const int flag = 0; + const struct rule rules[] = { + { + .path = "/dev/tty0", + .access = variant->allowed, + }, + {}, + }; + int file_fd, ruleset_fd; + + if (variant->allowed & LANDLOCK_ACCESS_FS_READ_DIR) { + SKIP(return, "LANDLOCK_ACCESS_FS_READ_DIR " + "can not be granted on files"); + } + + /* Enables Landlock. */ + ruleset_fd = create_ruleset(_metadata, variant->handled, rules); + ASSERT_LE(0, ruleset_fd); + enforce_ruleset(_metadata, ruleset_fd); + ASSERT_EQ(0, close(ruleset_fd)); + + file_fd = open("/dev/tty0", variant->open_mode); + ASSERT_LE(0, file_fd) + { + TH_LOG("Failed to open /dev/tty0: %s", strerror(errno)); + } + + /* Checks that IOCTL commands return the expected errors. */ + EXPECT_EQ(variant->expected_tcgets_result, test_tcgets_ioctl(file_fd)); + EXPECT_EQ(variant->expected_fionread_result, + test_fionread_ioctl(file_fd)); + + /* Checks that unrestrictable commands are unrestricted. */ + EXPECT_EQ(0, ioctl(file_fd, FIOCLEX)); + EXPECT_EQ(0, ioctl(file_fd, FIONCLEX)); + EXPECT_EQ(0, ioctl(file_fd, FIONBIO, &flag)); + EXPECT_EQ(0, ioctl(file_fd, FIOASYNC, &flag)); + EXPECT_EQ(0, ioctl(file_fd, FIGETBSZ, &flag)); + + ASSERT_EQ(0, close(file_fd)); +} + /* clang-format off */ FIXTURE(layout1_bind) {}; /* clang-format on */ -- 2.44.0.396.g6e790dbe36-goog
