[PATCH v7 02/14] selftests/memfd: Add tests for F_SEAL_AUTO_ALLOCATE

[Chao Peng]

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

Signed-off-by: Chao Peng <chao.p.peng@linux.intel.com>
---
 tools/testing/selftests/memfd/memfd_test.c | 166 +++++++++++++++++++++
 1 file changed, 166 insertions(+)

diff --git a/tools/testing/selftests/memfd/memfd_test.c 
b/tools/testing/selftests/memfd/memfd_test.c
index 94df2692e6e4..b849ece295fd 100644
--- a/tools/testing/selftests/memfd/memfd_test.c
+++ b/tools/testing/selftests/memfd/memfd_test.c
@@ -9,6 +9,7 @@
 #include <fcntl.h>
 #include <linux/memfd.h>
 #include <sched.h>
+#include <setjmp.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <signal.h>
@@ -232,6 +233,31 @@ static void mfd_fail_open(int fd, int flags, mode_t mode)
        }
 }
 
+static void mfd_assert_fallocate(int fd)
+{
+       int r;
+
+       r = fallocate(fd, 0, 0, mfd_def_size);
+       if (r < 0) {
+               printf("fallocate(ALLOC) failed: %m\n");
+               abort();
+       }
+}
+
+static void mfd_assert_punch_hole(int fd)
+{
+       int r;
+
+       r = fallocate(fd,
+                     FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE,
+                     0,
+                     mfd_def_size);
+       if (r < 0) {
+               printf("fallocate(PUNCH_HOLE) failed: %m\n");
+               abort();
+       }
+}
+
 static void mfd_assert_read(int fd)
 {
        char buf[16];
@@ -594,6 +620,94 @@ static void mfd_fail_grow_write(int fd)
        }
 }
 
+static void mfd_assert_hole_write(int fd)
+{
+       ssize_t l;
+       void *p;
+       char *p1;
+
+       /*
+        * huegtlbfs does not support write, but we want to
+        * verify everything else here.
+        */
+       if (!hugetlbfs_test) {
+               /* verify direct write() succeeds */
+               l = write(fd, "\0\0\0\0", 4);
+               if (l != 4) {
+                       printf("write() failed: %m\n");
+                       abort();
+               }
+       }
+
+       /* verify mmaped write succeeds */
+       p = mmap(NULL,
+                mfd_def_size,
+                PROT_READ | PROT_WRITE,
+                MAP_SHARED,
+                fd,
+                0);
+       if (p == MAP_FAILED) {
+               printf("mmap() failed: %m\n");
+               abort();
+       }
+       p1 = (char *)p + mfd_def_size - 1;
+       *p1 = 'H';
+       if (*p1 != 'H') {
+               printf("mmaped write failed: %m\n");
+               abort();
+
+       }
+       munmap(p, mfd_def_size);
+}
+
+sigjmp_buf jbuf, *sigbuf;
+static void sig_handler(int sig, siginfo_t *siginfo, void *ptr)
+{
+       if (sig == SIGBUS) {
+               if (sigbuf)
+                       siglongjmp(*sigbuf, 1);
+               abort();
+       }
+}
+
+static void mfd_fail_hole_write(int fd)
+{
+       ssize_t l;
+       void *p;
+       char *p1;
+
+       /* verify direct write() fails */
+       l = write(fd, "data", 4);
+       if (l > 0) {
+               printf("expected failure on write(), but got %d: %m\n", (int)l);
+               abort();
+       }
+
+       /* verify mmaped write fails */
+       p = mmap(NULL,
+                mfd_def_size,
+                PROT_READ | PROT_WRITE,
+                MAP_SHARED,
+                fd,
+                0);
+       if (p == MAP_FAILED) {
+               printf("mmap() failed: %m\n");
+               abort();
+       }
+
+       sigbuf = &jbuf;
+       if (sigsetjmp(*sigbuf, 1))
+               goto out;
+
+       /* Below write should trigger SIGBUS signal */
+       p1 = (char *)p + mfd_def_size - 1;
+       *p1 = 'H';
+       printf("failed to receive SIGBUS for mmaped write: %m\n");
+       abort();
+out:
+       munmap(p, mfd_def_size);
+}
+
 static int idle_thread_fn(void *arg)
 {
        sigset_t set;
@@ -880,6 +994,57 @@ static void test_seal_resize(void)
        close(fd);
 }
 
+/*
+ * Test F_SEAL_AUTO_ALLOCATE
+ * Test whether F_SEAL_AUTO_ALLOCATE actually prevents allocation.
+ */
+static void test_seal_auto_allocate(void)
+{
+       struct sigaction act;
+       int fd;
+
+       printf("%s SEAL-AUTO-ALLOCATE\n", memfd_str);
+
+       memset(&act, 0, sizeof(act));
+       act.sa_sigaction = sig_handler;
+       act.sa_flags = SA_SIGINFO;
+       if (sigaction(SIGBUS, &act, 0)) {
+               printf("sigaction() failed: %m\n");
+               abort();
+       }
+
+       fd = mfd_assert_new("kern_memfd_seal_auto_allocate",
+                           mfd_def_size,
+                           MFD_CLOEXEC | MFD_ALLOW_SEALING);
+
+       /* read/write should pass if F_SEAL_AUTO_ALLOCATE not set */
+       mfd_assert_read(fd);
+       mfd_assert_hole_write(fd);
+
+       mfd_assert_has_seals(fd, 0);
+       mfd_assert_add_seals(fd, F_SEAL_AUTO_ALLOCATE);
+       mfd_assert_has_seals(fd, F_SEAL_AUTO_ALLOCATE);
+
+       /* read/write should pass for pre-allocated area */
+       mfd_assert_read(fd);
+       mfd_assert_hole_write(fd);
+
+       mfd_assert_punch_hole(fd);
+
+       /* read should pass, write should fail in hole */
+       mfd_assert_read(fd);
+       mfd_fail_hole_write(fd);
+
+       mfd_assert_fallocate(fd);
+
+       /* read/write should pass after fallocate */
+       mfd_assert_read(fd);
+       mfd_assert_hole_write(fd);
+
+       close(fd);
+}
+
+
 /*
  * Test sharing via dup()
  * Test that seals are shared between dupped FDs and they're all equal.
@@ -1059,6 +1224,7 @@ int main(int argc, char **argv)
        test_seal_shrink();
        test_seal_grow();
        test_seal_resize();
+       test_seal_auto_allocate();
 
        test_share_dup("SHARE-DUP", "");
        test_share_mmap("SHARE-MMAP", "");
-- 
2.25.1