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Commit ac8ed5f9 authored by Joel Fernandes (Google)'s avatar Joel Fernandes (Google) Committed by Joel Fernandes
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UPSTREAM: selftests/memfd: Add tests for F_SEAL_FUTURE_WRITE seal 



Add tests to verify sealing memfds with the F_SEAL_FUTURE_WRITE works as
expected.

Cc: dancol@google.com
Cc: minchan@kernel.org
Cc: Jann Horn <jannh@google.com>
Cc: John Stultz <john.stultz@linaro.org>
Signed-off-by: default avatarJoel Fernandes (Google) <joel@joelfernandes.org>
Reviewed-by: default avatarShuah Khan <shuah@kernel.org>
Change-Id: I42a0ceb1f584a5444ec755f8c76899499bcbaddd
parent dec031f6

tools/testing/selftests/memfd/memfd_test.c

+74 −0
Original line number Diff line number Diff line
@@ -54,6 +54,22 @@ static int mfd_assert_new(const char *name, loff_t sz, unsigned int flags) 
	return fd;

}



static int mfd_assert_reopen_fd(int fd_in)

{

	int r, fd;

	char path[100];



	sprintf(path, "/proc/self/fd/%d", fd_in);



	fd = open(path, O_RDWR);

	if (fd < 0) {

		printf("re-open of existing fd %d failed\n", fd_in);

		abort();

	}



	return fd;

}



static void mfd_fail_new(const char *name, unsigned int flags)

{

	int r;
@@ -255,6 +271,25 @@ static void mfd_assert_read(int fd) 
	munmap(p, mfd_def_size);

}



/* Test that PROT_READ + MAP_SHARED mappings work. */

static void mfd_assert_read_shared(int fd)

{

	void *p;



	/* verify PROT_READ and MAP_SHARED *is* allowed */

	p = mmap(NULL,

		 mfd_def_size,

		 PROT_READ,

		 MAP_SHARED,

		 fd,

		 0);

	if (p == MAP_FAILED) {

		printf("mmap() failed: %m\n");

		abort();

	}

	munmap(p, mfd_def_size);

}



static void mfd_assert_write(int fd)

{

	ssize_t l;
@@ -692,6 +727,44 @@ static void test_seal_write(void) 
	close(fd);

}



/*

 * Test SEAL_FUTURE_WRITE

 * Test whether SEAL_FUTURE_WRITE actually prevents modifications.

 */

static void test_seal_future_write(void)

{

	int fd, fd2;

	void *p;



	printf("%s SEAL-FUTURE-WRITE\n", memfd_str);



	fd = mfd_assert_new("kern_memfd_seal_future_write",

			    mfd_def_size,

			    MFD_CLOEXEC | MFD_ALLOW_SEALING);



	p = mfd_assert_mmap_shared(fd);



	mfd_assert_has_seals(fd, 0);



	mfd_assert_add_seals(fd, F_SEAL_FUTURE_WRITE);

	mfd_assert_has_seals(fd, F_SEAL_FUTURE_WRITE);



	/* read should pass, writes should fail */

	mfd_assert_read(fd);

	mfd_assert_read_shared(fd);

	mfd_fail_write(fd);



	fd2 = mfd_assert_reopen_fd(fd);

	/* read should pass, writes should still fail */

	mfd_assert_read(fd2);

	mfd_assert_read_shared(fd2);

	mfd_fail_write(fd2);



	munmap(p, mfd_def_size);

	close(fd2);

	close(fd);

}



/*

 * Test SEAL_SHRINK

 * Test whether SEAL_SHRINK actually prevents shrinking
@@ -945,6 +1018,7 @@ int main(int argc, char **argv) 
	test_basic();



	test_seal_write();

	test_seal_future_write();

	test_seal_shrink();

	test_seal_grow();

	test_seal_resize();