From: Lorenzo Stoakes lorenzo.stoakes@oracle.com

[ Upstream commit ea0916e01d0b0f2cce1369ac1494239a79827270 ]

Now we have reinstated the ability to map F_SEAL_WRITE mappings read-only, assert that we are able to do this in a test to ensure that we do not regress this again.

Link: https://lkml.kernel.org/r/a6377ec470b14c0539b4600cf8fa24bf2e4858ae.173280477... Signed-off-by: Lorenzo Stoakes lorenzo.stoakes@oracle.com Cc: Jann Horn jannh@google.com Cc: Julian Orth ju.orth@gmail.com Cc: Liam R. Howlett Liam.Howlett@Oracle.com Cc: Linus Torvalds torvalds@linux-foundation.org Cc: Shuah Khan shuah@kernel.org Cc: Vlastimil Babka vbabka@suse.cz Signed-off-by: Andrew Morton akpm@linux-foundation.org Cc: stable@vger.kernel.org Signed-off-by: Isaac J. Manjarres isaacmanjarres@google.com --- tools/testing/selftests/memfd/memfd_test.c | 43 ++++++++++++++++++++++ 1 file changed, 43 insertions(+)

diff --git a/tools/testing/selftests/memfd/memfd_test.c b/tools/testing/selftests/memfd/memfd_test.c index e92b60eecb7d..9c9c82fd18a7 100644 --- a/tools/testing/selftests/memfd/memfd_test.c +++ b/tools/testing/selftests/memfd/memfd_test.c @@ -285,6 +285,24 @@ static void *mfd_assert_mmap_shared(int fd) return p; }

+static void *mfd_assert_mmap_read_shared(int fd) +{ + void *p; + + p = mmap(NULL, + mfd_def_size, + PROT_READ, + MAP_SHARED, + fd, + 0); + if (p == MAP_FAILED) { + printf("mmap() failed: %m\n"); + abort(); + } + + return p; +} + static void *mfd_assert_mmap_private(int fd) { void *p; @@ -986,6 +1004,30 @@ static void test_seal_future_write(void) close(fd); }

+static void test_seal_write_map_read_shared(void) +{ + int fd; + void *p; + + printf("%s SEAL-WRITE-MAP-READ\n", memfd_str); + + fd = mfd_assert_new("kern_memfd_seal_write_map_read", + mfd_def_size, + MFD_CLOEXEC | MFD_ALLOW_SEALING); + + mfd_assert_add_seals(fd, F_SEAL_WRITE); + mfd_assert_has_seals(fd, F_SEAL_WRITE); + + p = mfd_assert_mmap_read_shared(fd); + + mfd_assert_read(fd); + mfd_assert_read_shared(fd); + mfd_fail_write(fd); + + munmap(p, mfd_def_size); + close(fd); +} + /* * Test SEAL_SHRINK * Test whether SEAL_SHRINK actually prevents shrinking @@ -1603,6 +1645,7 @@ int main(int argc, char **argv)

test_seal_write(); test_seal_future_write(); + test_seal_write_map_read_shared(); test_seal_shrink(); test_seal_grow(); test_seal_resize();