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Morgan" , John Johansen , Paul Moore Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Exercise various scenarios where Landlock domains are enforced across all of a processes' threads. Cc: Andrew G. Morgan Cc: John Johansen Cc: Micka=C3=ABl Sala=C3=BCn Cc: Paul Moore Cc: linux-security-module@vger.kernel.org Signed-off-by: G=C3=BCnther Noack --- tools/testing/selftests/landlock/base_test.c | 6 +- tools/testing/selftests/landlock/tsync_test.c | 161 ++++++++++++++++++ 2 files changed, 164 insertions(+), 3 deletions(-) create mode 100644 tools/testing/selftests/landlock/tsync_test.c diff --git a/tools/testing/selftests/landlock/base_test.c b/tools/testing/s= elftests/landlock/base_test.c index f4b1a275d8d9..0fea236ef4bd 100644 --- a/tools/testing/selftests/landlock/base_test.c +++ b/tools/testing/selftests/landlock/base_test.c @@ -288,7 +288,7 @@ TEST(restrict_self_fd) EXPECT_EQ(EBADFD, errno); } =20 -TEST(restrict_self_fd_flags) +TEST(restrict_self_fd_logging_flags) { int fd; =20 @@ -304,9 +304,9 @@ TEST(restrict_self_fd_flags) EXPECT_EQ(EBADFD, errno); } =20 -TEST(restrict_self_flags) +TEST(restrict_self_logging_flags) { - const __u32 last_flag =3D LANDLOCK_RESTRICT_SELF_LOG_SUBDOMAINS_OFF; + const __u32 last_flag =3D LANDLOCK_RESTRICT_SELF_TSYNC; =20 /* Tests invalid flag combinations. */ =20 diff --git a/tools/testing/selftests/landlock/tsync_test.c b/tools/testing/= selftests/landlock/tsync_test.c new file mode 100644 index 000000000000..3971e0f02c49 --- /dev/null +++ b/tools/testing/selftests/landlock/tsync_test.c @@ -0,0 +1,161 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Landlock tests - Enforcing the same restrictions across multiple thread= s + * + * Copyright =C2=A9 2025 G=C3=BCnther Noack + */ + +#define _GNU_SOURCE +#include +#include +#include + +#include "common.h" + +/* create_ruleset - Create a simple ruleset FD common to all tests */ +static int create_ruleset(struct __test_metadata *const _metadata) +{ + struct landlock_ruleset_attr ruleset_attr =3D { + .handled_access_fs =3D (LANDLOCK_ACCESS_FS_WRITE_FILE | + LANDLOCK_ACCESS_FS_TRUNCATE), + }; + const int ruleset_fd =3D + landlock_create_ruleset(&ruleset_attr, sizeof(ruleset_attr), 0); + + ASSERT_LE(0, ruleset_fd) + { + TH_LOG("landlock_create_ruleset: %s", strerror(errno)); + } + return ruleset_fd; +} + +TEST(single_threaded_success) +{ + const int ruleset_fd =3D create_ruleset(_metadata); + + disable_caps(_metadata); + + ASSERT_EQ(0, prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0)); + ASSERT_EQ(0, landlock_restrict_self(ruleset_fd, + LANDLOCK_RESTRICT_SELF_TSYNC)); + + ASSERT_EQ(0, close(ruleset_fd)); +} + +void store_no_new_privs(void *data) +{ + bool *nnp =3D data; + + if (!nnp) + return; + *nnp =3D prctl(PR_GET_NO_NEW_PRIVS, 0, 0, 0, 0); +} + +void *idle(void *data) +{ + pthread_cleanup_push(store_no_new_privs, data); + + while (true) + sleep(1); + + pthread_cleanup_pop(1); +} + +TEST(multi_threaded_success) +{ + pthread_t t1, t2; + bool no_new_privs1, no_new_privs2; + const int ruleset_fd =3D create_ruleset(_metadata); + + disable_caps(_metadata); + + ASSERT_EQ(0, pthread_create(&t1, NULL, idle, &no_new_privs1)); + ASSERT_EQ(0, pthread_create(&t2, NULL, idle, &no_new_privs2)); + + ASSERT_EQ(0, prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0)); + + EXPECT_EQ(0, landlock_restrict_self(ruleset_fd, + LANDLOCK_RESTRICT_SELF_TSYNC)); + + ASSERT_EQ(0, pthread_cancel(t1)); + ASSERT_EQ(0, pthread_cancel(t2)); + ASSERT_EQ(0, pthread_join(t1, NULL)); + ASSERT_EQ(0, pthread_join(t2, NULL)); + + /* The no_new_privs flag was implicitly enabled on all threads. */ + EXPECT_TRUE(no_new_privs1); + EXPECT_TRUE(no_new_privs2); + + ASSERT_EQ(0, close(ruleset_fd)); +} + +TEST(multi_threaded_success_despite_diverging_domains) +{ + pthread_t t1, t2; + const int ruleset_fd =3D create_ruleset(_metadata); + + disable_caps(_metadata); + + ASSERT_EQ(0, prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0)); + + ASSERT_EQ(0, pthread_create(&t1, NULL, idle, NULL)); + ASSERT_EQ(0, pthread_create(&t2, NULL, idle, NULL)); + + /* + * The main thread enforces a ruleset, + * thereby bringing the threads' Landlock domains out of sync. + */ + EXPECT_EQ(0, landlock_restrict_self(ruleset_fd, 0)); + + /* Still, TSYNC succeeds, bringing the threads in sync again. */ + EXPECT_EQ(0, landlock_restrict_self(ruleset_fd, + LANDLOCK_RESTRICT_SELF_TSYNC)); + + ASSERT_EQ(0, pthread_cancel(t1)); + ASSERT_EQ(0, pthread_cancel(t2)); + ASSERT_EQ(0, pthread_join(t1, NULL)); + ASSERT_EQ(0, pthread_join(t2, NULL)); + ASSERT_EQ(0, close(ruleset_fd)); +} + +struct thread_restrict_data { + pthread_t t; + int ruleset_fd; + int result; +}; + +void *thread_restrict(void *data) +{ + struct thread_restrict_data *d =3D data; + + d->result =3D landlock_restrict_self(d->ruleset_fd, + LANDLOCK_RESTRICT_SELF_TSYNC); + return NULL; +} + +TEST(competing_enablement) +{ + const int ruleset_fd =3D create_ruleset(_metadata); + struct thread_restrict_data d[] =3D { + { .ruleset_fd =3D ruleset_fd }, + { .ruleset_fd =3D ruleset_fd }, + }; + + disable_caps(_metadata); + + ASSERT_EQ(0, prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0)); + ASSERT_EQ(0, pthread_create(&d[0].t, NULL, thread_restrict, &d[0])); + ASSERT_EQ(0, pthread_create(&d[1].t, NULL, thread_restrict, &d[1])); + + /* Wait for threads to finish. */ + ASSERT_EQ(0, pthread_join(d[0].t, NULL)); + ASSERT_EQ(0, pthread_join(d[1].t, NULL)); + + /* Expect that both succeeded. */ + EXPECT_EQ(0, d[0].result); + EXPECT_EQ(0, d[1].result); + + ASSERT_EQ(0, close(ruleset_fd)); +} + +TEST_HARNESS_MAIN --=20 2.52.0.177.g9f829587af-goog