[v13,22/24] selftests/vm: testcases must restore pkey-permissions

Message ID 1528937115-10132-23-git-send-email-linuxram@us.ibm.com
State New
Headers show
Series
  • selftests, powerpc, x86 : Memory Protection Keys
Related show

Commit Message

Ram Pai June 14, 2018, 12:45 a.m.
Generally the signal handler restores the state of the pkey register
before returning. However there are times when the read/write operation
can legitamely fail without invoking the signal handler.  Eg: A
sys_read() operaton to a write-protected page should be disallowed.  In
such a case the state of the pkey register is not restored to its
original state.  The test case is responsible for restoring the key
register state to its original value.

cc: Dave Hansen <dave.hansen@intel.com>
cc: Florian Weimer <fweimer@redhat.com>
Signed-off-by: Ram Pai <linuxram@us.ibm.com>
---
 tools/testing/selftests/vm/protection_keys.c |    5 +++++
 1 files changed, 5 insertions(+), 0 deletions(-)

Comments

Dave Hansen June 20, 2018, 3:20 p.m. | #1
On 06/13/2018 05:45 PM, Ram Pai wrote:
> Generally the signal handler restores the state of the pkey register
> before returning. However there are times when the read/write operation
> can legitamely fail without invoking the signal handler.  Eg: A
> sys_read() operaton to a write-protected page should be disallowed.  In
> such a case the state of the pkey register is not restored to its
> original state.  The test case is responsible for restoring the key
> register state to its original value.

Seems fragile.  Can't we just do this in common code?  We could just
loop through and restore the default permissions.  That seems much more
resistant to a bad test case.

Patch

diff --git a/tools/testing/selftests/vm/protection_keys.c b/tools/testing/selftests/vm/protection_keys.c
index caf634e..b5a9e6c 100644
--- a/tools/testing/selftests/vm/protection_keys.c
+++ b/tools/testing/selftests/vm/protection_keys.c
@@ -1011,6 +1011,7 @@  void test_read_of_write_disabled_region(int *ptr, u16 pkey)
 	ptr_contents = read_ptr(ptr);
 	dprintf1("*ptr: %d\n", ptr_contents);
 	dprintf1("\n");
+	pkey_write_allow(pkey);
 }
 void test_read_of_access_disabled_region(int *ptr, u16 pkey)
 {
@@ -1090,6 +1091,7 @@  void test_kernel_write_of_access_disabled_region(int *ptr, u16 pkey)
 	ret = read(test_fd, ptr, 1);
 	dprintf1("read ret: %d\n", ret);
 	pkey_assert(ret);
+	pkey_access_allow(pkey);
 }
 void test_kernel_write_of_write_disabled_region(int *ptr, u16 pkey)
 {
@@ -1102,6 +1104,7 @@  void test_kernel_write_of_write_disabled_region(int *ptr, u16 pkey)
 	if (ret < 0 && (DEBUG_LEVEL > 0))
 		perror("verbose read result (OK for this to be bad)");
 	pkey_assert(ret);
+	pkey_write_allow(pkey);
 }
 
 void test_kernel_gup_of_access_disabled_region(int *ptr, u16 pkey)
@@ -1121,6 +1124,7 @@  void test_kernel_gup_of_access_disabled_region(int *ptr, u16 pkey)
 	vmsplice_ret = vmsplice(pipe_fds[1], &iov, 1, SPLICE_F_GIFT);
 	dprintf1("vmsplice() ret: %d\n", vmsplice_ret);
 	pkey_assert(vmsplice_ret == -1);
+	pkey_access_allow(pkey);
 
 	close(pipe_fds[0]);
 	close(pipe_fds[1]);
@@ -1141,6 +1145,7 @@  void test_kernel_gup_write_to_write_disabled_region(int *ptr, u16 pkey)
 	if (DEBUG_LEVEL > 0)
 		perror("futex");
 	dprintf1("futex() ret: %d\n", futex_ret);
+	pkey_write_allow(pkey);
 }
 
 /* Assumes that all pkeys other than 'pkey' are unallocated */