Hi Shuah Khan
I will continue Daniel Verkamp's work on this patch.
Could you please take a look at the new patch set I sent to see if all your comments are addressed ?
Much appreciated.
Best Regards, Jeff.
On Thu, Jul 28, 2022 at 11:15 PM Jeff Xu jeffxu@google.com wrote:
From: Daniel Verkamp dverkamp@chromium.org
Basic tests to ensure that user/group/other execute bits cannot be changed after applying F_SEAL_EXEC to a memfd.
Co-developed-by: Jeff Xu jeffxu@google.com Signed-off-by: Jeff Xu jeffxu@google.com Signed-off-by: Daniel Verkamp dverkamp@chromium.org
tools/testing/selftests/memfd/memfd_test.c | 129 ++++++++++++++++++++- 1 file changed, 128 insertions(+), 1 deletion(-)
diff --git a/tools/testing/selftests/memfd/memfd_test.c b/tools/testing/selftests/memfd/memfd_test.c index 94df2692e6e4..1d7e7b36bbdd 100644 --- a/tools/testing/selftests/memfd/memfd_test.c +++ b/tools/testing/selftests/memfd/memfd_test.c @@ -28,12 +28,44 @@ #define MFD_DEF_SIZE 8192 #define STACK_SIZE 65536
+#ifndef F_SEAL_EXEC +#define F_SEAL_EXEC 0x0020 +#endif
+#ifndef MAX_PATH +#define MAX_PATH 256 +#endif
/*
- Default is not to test hugetlbfs
*/ static size_t mfd_def_size = MFD_DEF_SIZE; static const char *memfd_str = MEMFD_STR;
+static ssize_t fd2name(int fd, char *buf, size_t bufsize) +{
char buf1[MAX_PATH];int size;ssize_t nbytes;size = snprintf(buf1, MAX_PATH, "/proc/self/fd/%d", fd);if (size < 0) {printf("snprintf(%d) failed on %m\n", fd);abort();}/** reserver one byte for string termination.*/nbytes = readlink(buf1, buf, bufsize-1);if (nbytes == -1) {printf("readlink(%s) failed %m\n", buf1);abort();}buf[nbytes] = '\0';return nbytes;+}
static int mfd_assert_new(const char *name, loff_t sz, unsigned int flags) { int r, fd; @@ -98,11 +130,14 @@ static unsigned int mfd_assert_get_seals(int fd)
static void mfd_assert_has_seals(int fd, unsigned int seals) {
char buf[MAX_PATH];int nbytes; unsigned int s;fd2name(fd, buf, MAX_PATH); s = mfd_assert_get_seals(fd); if (s != seals) {
printf("%u != %u = GET_SEALS(%d)\n", seals, s, fd);
printf("%u != %u = GET_SEALS(%s)\n", seals, s, buf); abort(); }} @@ -594,6 +629,64 @@ static void mfd_fail_grow_write(int fd) } }
+static void mfd_assert_mode(int fd, int mode) +{
struct stat st;char buf[MAX_PATH];int nbytes;fd2name(fd, buf, MAX_PATH);if (fstat(fd, &st) < 0) {printf("fstat(%s) failed: %m\n", buf);abort();}if ((st.st_mode & 07777) != mode) {printf("fstat(%s) wrong file mode 0%04o, but expected 0%04o\n",buf, (int)st.st_mode & 07777, mode);abort();}+}
+static void mfd_assert_chmod(int fd, int mode) +{
char buf[MAX_PATH];int nbytes;fd2name(fd, buf, MAX_PATH);if (fchmod(fd, mode) < 0) {printf("fchmod(%s, 0%04o) failed: %m\n", buf, mode);abort();}mfd_assert_mode(fd, mode);+}
+static void mfd_fail_chmod(int fd, int mode) +{
struct stat st;char buf[MAX_PATH];int nbytes;fd2name(fd, buf, MAX_PATH);if (fstat(fd, &st) < 0) {printf("fstat(%s) failed: %m\n", buf);abort();}if (fchmod(fd, mode) == 0) {printf("fchmod(%s, 0%04o) didn't fail as expected\n",buf, mode);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 +973,39 @@ 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 +1185,7 @@ 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", "");-- 2.37.1.455.g008518b4e5-goog