Patch "x86/pkeys/selftests: Add PROT_EXEC test" has been added to the 4.16-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    x86/pkeys/selftests: Add PROT_EXEC test

to the 4.16-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     x86-pkeys-selftests-add-prot_exec-test.patch
and it can be found in the queue-4.16 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From foo@baz Sun Jun 17 12:07:34 CEST 2018
From: Dave Hansen <dave.hansen@linux.intel.com>
Date: Wed, 9 May 2018 10:13:48 -0700
Subject: x86/pkeys/selftests: Add PROT_EXEC test

From: Dave Hansen <dave.hansen@linux.intel.com>

[ Upstream commit 6af17cf89e99b64cf1f660bf848755442ab2f047 ]

Under the covers, implement executable-only memory with
protection keys when userspace calls mprotect(PROT_EXEC).

But, we did not have a selftest for that.  Now we do.

Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Michael Ellermen <mpe@ellerman.id.au>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ram Pai <linuxram@us.ibm.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/20180509171348.9EEE4BEF@viggo.jf.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 tools/testing/selftests/x86/protection_keys.c |   44 ++++++++++++++++++++++++++
 1 file changed, 44 insertions(+)

--- a/tools/testing/selftests/x86/protection_keys.c
+++ b/tools/testing/selftests/x86/protection_keys.c
@@ -1303,6 +1303,49 @@ void test_executing_on_unreadable_memory
 	expected_pk_fault(pkey);
 }
 
+void test_implicit_mprotect_exec_only_memory(int *ptr, u16 pkey)
+{
+	void *p1;
+	int scratch;
+	int ptr_contents;
+	int ret;
+
+	dprintf1("%s() start\n", __func__);
+
+	p1 = get_pointer_to_instructions();
+	lots_o_noops_around_write(&scratch);
+	ptr_contents = read_ptr(p1);
+	dprintf2("ptr (%p) contents@%d: %x\n", p1, __LINE__, ptr_contents);
+
+	/* Use a *normal* mprotect(), not mprotect_pkey(): */
+	ret = mprotect(p1, PAGE_SIZE, PROT_EXEC);
+	pkey_assert(!ret);
+
+	dprintf2("pkru: %x\n", rdpkru());
+
+	/* Make sure this is an *instruction* fault */
+	madvise(p1, PAGE_SIZE, MADV_DONTNEED);
+	lots_o_noops_around_write(&scratch);
+	do_not_expect_pk_fault("executing on PROT_EXEC memory");
+	ptr_contents = read_ptr(p1);
+	dprintf2("ptr (%p) contents@%d: %x\n", p1, __LINE__, ptr_contents);
+	expected_pk_fault(UNKNOWN_PKEY);
+
+	/*
+	 * Put the memory back to non-PROT_EXEC.  Should clear the
+	 * exec-only pkey off the VMA and allow it to be readable
+	 * again.  Go to PROT_NONE first to check for a kernel bug
+	 * that did not clear the pkey when doing PROT_NONE.
+	 */
+	ret = mprotect(p1, PAGE_SIZE, PROT_NONE);
+	pkey_assert(!ret);
+
+	ret = mprotect(p1, PAGE_SIZE, PROT_READ|PROT_EXEC);
+	pkey_assert(!ret);
+	ptr_contents = read_ptr(p1);
+	do_not_expect_pk_fault("plain read on recently PROT_EXEC area");
+}
+
 void test_mprotect_pkey_on_unsupported_cpu(int *ptr, u16 pkey)
 {
 	int size = PAGE_SIZE;
@@ -1327,6 +1370,7 @@ void (*pkey_tests[])(int *ptr, u16 pkey)
 	test_kernel_gup_of_access_disabled_region,
 	test_kernel_gup_write_to_write_disabled_region,
 	test_executing_on_unreadable_memory,
+	test_implicit_mprotect_exec_only_memory,
 	test_ptrace_of_child,
 	test_pkey_syscalls_on_non_allocated_pkey,
 	test_pkey_syscalls_bad_args,


Patches currently in stable-queue which might be from dave.hansen@linux.intel.com are

queue-4.16/x86-pkeys-selftests-factor-out-instruction-page.patch
queue-4.16/x86-pkeys-selftests-fix-pointer-math.patch
queue-4.16/x86-pkeys-selftests-adjust-the-self-test-to-fresh-distros-that-export-the-pkeys-abi.patch
queue-4.16/x86-pkeys-selftests-add-a-test-for-pkey-0.patch
queue-4.16/x86-pkeys-selftests-stop-using-assert.patch
queue-4.16/x86-pkeys-selftests-save-off-prot-for-allocations.patch
queue-4.16/x86-pkeys-selftests-remove-dead-debugging-code-fix-dprint_in_signal.patch
queue-4.16/x86-mpx-selftests-adjust-the-self-test-to-fresh-distros-that-export-the-mpx-abi.patch
queue-4.16/x86-pkeys-selftests-add-prot_exec-test.patch
queue-4.16/x86-pkeys-selftests-allow-faults-on-unknown-keys.patch
queue-4.16/x86-pkeys-selftests-give-better-unexpected-fault-error-messages.patch
queue-4.16/x86-pkeys-selftests-avoid-printf-in-signal-deadlocks.patch
queue-4.16/x86-pkeys-selftests-fix-pkey-exhaustion-test-off-by-one.patch