selftests/memfd: add test for mapping write-sealed memfd read-only

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.1732804776.git.lorenzo.stoakes@oracle.com
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>
This commit is contained in:
Lorenzo Stoakes 2024-11-28 15:06:18 +00:00 committed by Andrew Morton
parent 8ec396d05d
commit ea0916e01d

View File

@ -282,6 +282,24 @@ 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;
@ -980,6 +998,30 @@ 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
@ -1593,6 +1635,7 @@ 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();