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selftests/memfd: add tests for F_SEAL_FUTURE_WRITE seal

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

Link: http://lkml.kernel.org/r/20190112203816.85534-3-joel@joelfernandes.org
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Reviewed-by: Shuah Khan <shuah@kernel.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jann Horn <jannh@google.com>
Cc: J. Bruce Fields <bfields@fieldses.org>
Cc: Jeff Layton <jlayton@kernel.org>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Marc-Andr Lureau <marcandre.lureau@redhat.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Minchan Kim <minchan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Joel Fernandes (Google) 2019-03-05 15:47:58 -08:00 committed by Linus Torvalds
parent ab3948f58f
commit 544029862c
1 changed files with 74 additions and 0 deletions
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74
tools/testing/selftests/memfd/memfd_test.c
View File

@ -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();