From 2dc539ac4d2f556105ea7e2a37d23379a79a47eb Mon Sep 17 00:00:00 2001 From: Florent Revest Date: Mon, 28 Aug 2023 17:08:58 +0200 Subject: [PATCH] kselftest: vm: add tests for no-inherit memory-deny-write-execute Add some tests to cover the new PR_MDWE_NO_INHERIT flag of the PR_SET_MDWE prctl. Check that: - it can't be set without PR_SET_MDWE - MDWE flags can't be unset - when set, PR_SET_MDWE doesn't propagate to children Link: https://lkml.kernel.org/r/20230828150858.393570-7-revest@chromium.org Signed-off-by: Florent Revest Acked-by: Catalin Marinas Reviewed-by: Kees Cook Cc: Alexey Izbyshev Cc: Anshuman Khandual Cc: Ayush Jain Cc: David Hildenbrand Cc: Greg Thelen Cc: Joey Gouly Cc: KP Singh Cc: Mark Brown Cc: Michal Hocko Cc: Peter Xu Cc: Ryan Roberts Cc: Szabolcs Nagy Cc: Topi Miettinen Signed-off-by: Andrew Morton --- tools/testing/selftests/mm/mdwe_test.c | 114 +++++++++++++++++++++++-- 1 file changed, 108 insertions(+), 6 deletions(-) diff --git a/tools/testing/selftests/mm/mdwe_test.c b/tools/testing/selftests/mm/mdwe_test.c index 1b84cf8e1bbe..200bedcdc32e 100644 --- a/tools/testing/selftests/mm/mdwe_test.c +++ b/tools/testing/selftests/mm/mdwe_test.c @@ -22,6 +22,9 @@ TEST(prctl_flags) { + EXPECT_LT(prctl(PR_SET_MDWE, PR_MDWE_NO_INHERIT, 0L, 0L, 7L), 0); + EXPECT_EQ(errno, EINVAL); + EXPECT_LT(prctl(PR_SET_MDWE, 7L, 0L, 0L, 0L), 0); EXPECT_EQ(errno, EINVAL); EXPECT_LT(prctl(PR_SET_MDWE, 0L, 7L, 0L, 0L), 0); @@ -41,6 +44,84 @@ TEST(prctl_flags) EXPECT_EQ(errno, EINVAL); } +FIXTURE(consecutive_prctl_flags) {}; +FIXTURE_SETUP(consecutive_prctl_flags) {} +FIXTURE_TEARDOWN(consecutive_prctl_flags) {} + +FIXTURE_VARIANT(consecutive_prctl_flags) +{ + unsigned long first_flags; + unsigned long second_flags; + bool should_work; +}; + +FIXTURE_VARIANT_ADD(consecutive_prctl_flags, can_keep_no_flags) +{ + .first_flags = 0, + .second_flags = 0, + .should_work = true, +}; + +FIXTURE_VARIANT_ADD(consecutive_prctl_flags, can_keep_exec_gain) +{ + .first_flags = PR_MDWE_REFUSE_EXEC_GAIN, + .second_flags = PR_MDWE_REFUSE_EXEC_GAIN, + .should_work = true, +}; + +FIXTURE_VARIANT_ADD(consecutive_prctl_flags, can_keep_both_flags) +{ + .first_flags = PR_MDWE_REFUSE_EXEC_GAIN | PR_MDWE_NO_INHERIT, + .second_flags = PR_MDWE_REFUSE_EXEC_GAIN | PR_MDWE_NO_INHERIT, + .should_work = true, +}; + +FIXTURE_VARIANT_ADD(consecutive_prctl_flags, cant_disable_mdwe) +{ + .first_flags = PR_MDWE_REFUSE_EXEC_GAIN, + .second_flags = 0, + .should_work = false, +}; + +FIXTURE_VARIANT_ADD(consecutive_prctl_flags, cant_disable_mdwe_no_inherit) +{ + .first_flags = PR_MDWE_REFUSE_EXEC_GAIN | PR_MDWE_NO_INHERIT, + .second_flags = 0, + .should_work = false, +}; + +FIXTURE_VARIANT_ADD(consecutive_prctl_flags, cant_disable_no_inherit) +{ + .first_flags = PR_MDWE_REFUSE_EXEC_GAIN | PR_MDWE_NO_INHERIT, + .second_flags = PR_MDWE_REFUSE_EXEC_GAIN, + .should_work = false, +}; + +FIXTURE_VARIANT_ADD(consecutive_prctl_flags, cant_enable_no_inherit) +{ + .first_flags = PR_MDWE_REFUSE_EXEC_GAIN, + .second_flags = PR_MDWE_REFUSE_EXEC_GAIN | PR_MDWE_NO_INHERIT, + .should_work = false, +}; + +TEST_F(consecutive_prctl_flags, two_prctls) +{ + int ret; + + EXPECT_EQ(prctl(PR_SET_MDWE, variant->first_flags, 0L, 0L, 0L), 0); + + ret = prctl(PR_SET_MDWE, variant->second_flags, 0L, 0L, 0L); + if (variant->should_work) { + EXPECT_EQ(ret, 0); + + ret = prctl(PR_GET_MDWE, 0L, 0L, 0L, 0L); + ASSERT_EQ(ret, variant->second_flags); + } else { + EXPECT_NE(ret, 0); + ASSERT_EQ(errno, EPERM); + } +} + FIXTURE(mdwe) { void *p; @@ -53,28 +134,45 @@ FIXTURE_VARIANT(mdwe) { bool enabled; bool forked; + bool inherit; }; FIXTURE_VARIANT_ADD(mdwe, stock) { .enabled = false, .forked = false, + .inherit = false, }; FIXTURE_VARIANT_ADD(mdwe, enabled) { .enabled = true, .forked = false, + .inherit = true, }; -FIXTURE_VARIANT_ADD(mdwe, forked) +FIXTURE_VARIANT_ADD(mdwe, inherited) { .enabled = true, .forked = true, + .inherit = true, }; +FIXTURE_VARIANT_ADD(mdwe, not_inherited) +{ + .enabled = true, + .forked = true, + .inherit = false, +}; + +static bool executable_map_should_fail(const FIXTURE_VARIANT(mdwe) *variant) +{ + return variant->enabled && (!variant->forked || variant->inherit); +} + FIXTURE_SETUP(mdwe) { + unsigned long mdwe_flags; int ret, status; self->p = NULL; @@ -84,13 +182,17 @@ FIXTURE_SETUP(mdwe) if (!variant->enabled) return; - ret = prctl(PR_SET_MDWE, PR_MDWE_REFUSE_EXEC_GAIN, 0L, 0L, 0L); + mdwe_flags = PR_MDWE_REFUSE_EXEC_GAIN; + if (!variant->inherit) + mdwe_flags |= PR_MDWE_NO_INHERIT; + + ret = prctl(PR_SET_MDWE, mdwe_flags, 0L, 0L, 0L); ASSERT_EQ(ret, 0) { TH_LOG("PR_SET_MDWE failed or unsupported"); } ret = prctl(PR_GET_MDWE, 0L, 0L, 0L, 0L); - ASSERT_EQ(ret, 1); + ASSERT_EQ(ret, mdwe_flags); if (variant->forked) { self->pid = fork(); @@ -121,7 +223,7 @@ TEST_F(mdwe, mmap_READ_EXEC) TEST_F(mdwe, mmap_WRITE_EXEC) { self->p = mmap(NULL, self->size, PROT_WRITE | PROT_EXEC, self->flags, 0, 0); - if (variant->enabled) { + if (executable_map_should_fail(variant)) { EXPECT_EQ(self->p, MAP_FAILED); } else { EXPECT_NE(self->p, MAP_FAILED); @@ -147,7 +249,7 @@ TEST_F(mdwe, mprotect_add_EXEC) ASSERT_NE(self->p, MAP_FAILED); ret = mprotect(self->p, self->size, PROT_READ | PROT_EXEC); - if (variant->enabled) { + if (executable_map_should_fail(variant)) { EXPECT_LT(ret, 0); } else { EXPECT_EQ(ret, 0); @@ -162,7 +264,7 @@ TEST_F(mdwe, mprotect_WRITE_EXEC) ASSERT_NE(self->p, MAP_FAILED); ret = mprotect(self->p, self->size, PROT_WRITE | PROT_EXEC); - if (variant->enabled) { + if (executable_map_should_fail(variant)) { EXPECT_LT(ret, 0); } else { EXPECT_EQ(ret, 0); -- 2.25.1