| Message ID | 20220401220834.307660-4-dverkamp@chromium.org (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | mm/memfd: MFD_NOEXEC for memfd_create | expand |
On 4/1/22 4:08 PM, Daniel Verkamp wrote: > Basic tests to ensure that user/group/other execute bits cannot be > changed after applying F_SEAL_EXEC to a memfd. > > Signed-off-by: Daniel Verkamp <dverkamp@chromium.org> > --- > tools/testing/selftests/memfd/memfd_test.c | 80 ++++++++++++++++++++++ > 1 file changed, 80 insertions(+) > > diff --git a/tools/testing/selftests/memfd/memfd_test.c b/tools/testing/selftests/memfd/memfd_test.c > index 94df2692e6e4..fdb0e46e9df9 100644 > --- a/tools/testing/selftests/memfd/memfd_test.c > +++ b/tools/testing/selftests/memfd/memfd_test.c > @@ -28,6 +28,10 @@ > #define MFD_DEF_SIZE 8192 > #define STACK_SIZE 65536 > > +#ifndef F_SEAL_EXEC > +#define F_SEAL_EXEC 0x0020 > +#endif > + > /* > * Default is not to test hugetlbfs > */ > @@ -594,6 +598,48 @@ static void mfd_fail_grow_write(int fd) > } > } > > +static void mfd_assert_mode(int fd, int mode) > +{ > + struct stat st; > + > + if (fstat(fd, &st) < 0) { > + printf("fstat(%d) failed: %m\n", fd); Let's print the filename here - just printing fd isn't useful. > + abort(); > + } else if ((st.st_mode & 07777) != mode) { > + printf("wrong file mode 0%04o, but expected 0%04o\n", > + (int)st.st_mode & 07777, mode); This one doesn't even print fd - same comment here about filename. > + abort(); > + } > +} > + > +static void mfd_assert_chmod(int fd, int mode) > +{ > + if (fchmod(fd, mode) < 0) { > + printf("fchmod(0%04o) failed: %m\n", mode); Same here. > + abort(); > + } > + > + mfd_assert_mode(fd, mode); > +} > + > +static void mfd_fail_chmod(int fd, int mode) > +{ > + struct stat st; > + > + if (fstat(fd, &st) < 0) { > + printf("fstat(%d) failed: %m\n", fd); Same comment about filename > + abort(); > + } > + > + if (fchmod(fd, mode) == 0) { > + printf("fchmod(0%04o) didn't fail as expected\n"); Same comment about filename > + abort(); > + } > + > + /* verify that file mode bits did not change */ > + mfd_assert_mode(fd, st.st_mode & 07777); > +} > + > static int idle_thread_fn(void *arg) > { > sigset_t set; > @@ -880,6 +926,39 @@ static void test_seal_resize(void) > close(fd); > } > > +/* > + * Test SEAL_EXEC > + * Test that chmod() cannot change x bits after sealing > + */ > +static void test_seal_exec(void) > +{ > + int fd; > + > + printf("%s SEAL-EXEC\n", memfd_str); > + > + fd = mfd_assert_new("kern_memfd_seal_exec", > + mfd_def_size, > + MFD_CLOEXEC | MFD_ALLOW_SEALING); > + > + mfd_assert_mode(fd, 0777); > + > + mfd_assert_chmod(fd, 0644); > + > + mfd_assert_has_seals(fd, 0); > + mfd_assert_add_seals(fd, F_SEAL_EXEC); > + mfd_assert_has_seals(fd, F_SEAL_EXEC); > + > + mfd_assert_chmod(fd, 0600); > + mfd_fail_chmod(fd, 0777); > + mfd_fail_chmod(fd, 0670); > + mfd_fail_chmod(fd, 0605); > + mfd_fail_chmod(fd, 0700); > + mfd_fail_chmod(fd, 0100); > + mfd_assert_chmod(fd, 0666); > + > + close(fd); > +} > + > /* > * Test sharing via dup() > * Test that seals are shared between dupped FDs and they're all equal. > @@ -1059,6 +1138,7 @@ int main(int argc, char **argv) > test_seal_shrink(); > test_seal_grow(); > test_seal_resize(); > + test_seal_exec(); > > test_share_dup("SHARE-DUP", ""); > test_share_mmap("SHARE-MMAP", ""); > The rest looks good. thanks, -- Shuah
diff --git a/tools/testing/selftests/memfd/memfd_test.c b/tools/testing/selftests/memfd/memfd_test.c index 94df2692e6e4..fdb0e46e9df9 100644 --- a/tools/testing/selftests/memfd/memfd_test.c +++ b/tools/testing/selftests/memfd/memfd_test.c @@ -28,6 +28,10 @@ #define MFD_DEF_SIZE 8192 #define STACK_SIZE 65536 +#ifndef F_SEAL_EXEC +#define F_SEAL_EXEC 0x0020 +#endif + /* * Default is not to test hugetlbfs */ @@ -594,6 +598,48 @@ static void mfd_fail_grow_write(int fd) } } +static void mfd_assert_mode(int fd, int mode) +{ + struct stat st; + + if (fstat(fd, &st) < 0) { + printf("fstat(%d) failed: %m\n", fd); + abort(); + } else if ((st.st_mode & 07777) != mode) { + printf("wrong file mode 0%04o, but expected 0%04o\n", + (int)st.st_mode & 07777, mode); + abort(); + } +} + +static void mfd_assert_chmod(int fd, int mode) +{ + if (fchmod(fd, mode) < 0) { + printf("fchmod(0%04o) failed: %m\n", mode); + abort(); + } + + mfd_assert_mode(fd, mode); +} + +static void mfd_fail_chmod(int fd, int mode) +{ + struct stat st; + + if (fstat(fd, &st) < 0) { + printf("fstat(%d) failed: %m\n", fd); + abort(); + } + + if (fchmod(fd, mode) == 0) { + printf("fchmod(0%04o) didn't fail as expected\n"); + abort(); + } + + /* verify that file mode bits did not change */ + mfd_assert_mode(fd, st.st_mode & 07777); +} + static int idle_thread_fn(void *arg) { sigset_t set; @@ -880,6 +926,39 @@ static void test_seal_resize(void) close(fd); } +/* + * Test SEAL_EXEC + * Test that chmod() cannot change x bits after sealing + */ +static void test_seal_exec(void) +{ + int fd; + + printf("%s SEAL-EXEC\n", memfd_str); + + fd = mfd_assert_new("kern_memfd_seal_exec", + mfd_def_size, + MFD_CLOEXEC | MFD_ALLOW_SEALING); + + mfd_assert_mode(fd, 0777); + + mfd_assert_chmod(fd, 0644); + + mfd_assert_has_seals(fd, 0); + mfd_assert_add_seals(fd, F_SEAL_EXEC); + mfd_assert_has_seals(fd, F_SEAL_EXEC); + + mfd_assert_chmod(fd, 0600); + mfd_fail_chmod(fd, 0777); + mfd_fail_chmod(fd, 0670); + mfd_fail_chmod(fd, 0605); + mfd_fail_chmod(fd, 0700); + mfd_fail_chmod(fd, 0100); + mfd_assert_chmod(fd, 0666); + + close(fd); +} + /* * Test sharing via dup() * Test that seals are shared between dupped FDs and they're all equal. @@ -1059,6 +1138,7 @@ int main(int argc, char **argv) test_seal_shrink(); test_seal_grow(); test_seal_resize(); + test_seal_exec(); test_share_dup("SHARE-DUP", ""); test_share_mmap("SHARE-MMAP", "");
Basic tests to ensure that user/group/other execute bits cannot be changed after applying F_SEAL_EXEC to a memfd. Signed-off-by: Daniel Verkamp <dverkamp@chromium.org> --- tools/testing/selftests/memfd/memfd_test.c | 80 ++++++++++++++++++++++ 1 file changed, 80 insertions(+)