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Date: Fri, 1 Apr 2022 15:08:34 -0700 From: Daniel Verkamp <dverkamp@...omium.org> To: linux-mm@...ck.org Cc: linux-kernel@...r.kernel.org, linux-kselftest@...r.kernel.org, Andrew Morton <akpm@...ux-foundation.org>, Hugh Dickins <hughd@...gle.com>, Mattias Nissler <mnissler@...omium.org>, Dmitry Torokhov <dmitry.torokhov@...il.com>, Kees Cook <keescook@...omium.org>, Daniel Verkamp <dverkamp@...omium.org> Subject: [PATCH 4/4] selftests/memfd: add tests for MFD_NOEXEC Tests that ensure MFD_NOEXEC memfds have the appropriate mode bits and cannot be chmod-ed into being executable. Signed-off-by: Daniel Verkamp <dverkamp@...omium.org> --- tools/testing/selftests/memfd/memfd_test.c | 34 ++++++++++++++++++++++ 1 file changed, 34 insertions(+) diff --git a/tools/testing/selftests/memfd/memfd_test.c b/tools/testing/selftests/memfd/memfd_test.c index fdb0e46e9df9..a79567161cdf 100644 --- a/tools/testing/selftests/memfd/memfd_test.c +++ b/tools/testing/selftests/memfd/memfd_test.c @@ -32,6 +32,10 @@ #define F_SEAL_EXEC 0x0020 #endif +#ifndef MFD_NOEXEC +#define MFD_NOEXEC 0x0008U +#endif + /* * Default is not to test hugetlbfs */ @@ -959,6 +963,35 @@ static void test_seal_exec(void) close(fd); } +/* + * Test memfd_create with MFD_NOEXEC flag + * Test that MFD_NOEXEC applies F_SEAL_EXEC and prevents change of exec bits + */ +static void test_noexec(void) +{ + int fd; + + printf("%s NOEXEC\n", memfd_str); + + /* Create with NOEXEC and ALLOW_SEALING */ + fd = mfd_assert_new("kern_memfd_noexec", + mfd_def_size, + MFD_CLOEXEC | MFD_ALLOW_SEALING | MFD_NOEXEC); + mfd_assert_mode(fd, 0666); + mfd_assert_has_seals(fd, F_SEAL_EXEC); + mfd_fail_chmod(fd, 0777); + close(fd); + + /* Create with NOEXEC but without ALLOW_SEALING */ + fd = mfd_assert_new("kern_memfd_noexec", + mfd_def_size, + MFD_CLOEXEC | MFD_NOEXEC); + mfd_assert_mode(fd, 0666); + mfd_assert_has_seals(fd, F_SEAL_EXEC | F_SEAL_SEAL); + mfd_fail_chmod(fd, 0777); + close(fd); +} + /* * Test sharing via dup() * Test that seals are shared between dupped FDs and they're all equal. @@ -1132,6 +1165,7 @@ int main(int argc, char **argv) test_create(); test_basic(); + test_noexec(); test_seal_write(); test_seal_future_write(); -- 2.35.1.1094.g7c7d902a7c-goog
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