[PATCH v13 02/10] selftests/landlock: Test IOCTL support
Günther Noack
gnoack at google.com
Wed Mar 27 13:10:32 UTC 2024
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 at google.com>
---
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
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