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From: Dave Hansen <dave.hansen@linux.intel.com>
To: linux-kernel@vger.kernel.org
Cc: linux-mm@kvack.org, Dave Hansen <dave.hansen@linux.intel.com>,
	linuxram@us.ibm.com, tglx@linutronix.de, dave.hansen@intel.com,
	mpe@ellerman.id.au, mingo@kernel.org, akpm@linux-foundation.org,
	shuah@kernel.org
Subject: [PATCH 9/9] x86, pkeys, selftests: add PROT_EXEC test
Date: Mon, 26 Mar 2018 10:27:35 -0700	[thread overview]
Message-ID: <20180326172735.EFE9EF33@viggo.jf.intel.com> (raw)
In-Reply-To: <20180326172721.D5B2CBB4@viggo.jf.intel.com>


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

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: Ram Pai <linuxram@us.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Michael Ellermen <mpe@ellerman.id.au>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Shuah Khan <shuah@kernel.org>
---

 b/tools/testing/selftests/x86/protection_keys.c |   51 ++++++++++++++++++++++--
 1 file changed, 47 insertions(+), 4 deletions(-)

diff -puN tools/testing/selftests/x86/protection_keys.c~pkeys-selftests-prot_exec tools/testing/selftests/x86/protection_keys.c
--- a/tools/testing/selftests/x86/protection_keys.c~pkeys-selftests-prot_exec	2018-03-26 10:22:38.087170186 -0700
+++ b/tools/testing/selftests/x86/protection_keys.c	2018-03-26 10:22:38.091170186 -0700
@@ -930,10 +930,10 @@ void expected_pk_fault(int pkey)
 	dprintf2("%s(%d): last_si_pkey: %d\n", __func__, pkey, last_si_pkey);
 	pkey_assert(last_pkru_faults + 1 == pkru_faults);
 
-       /*
-	* For exec-only memory, we do not know the pkey in
-	* advance, so skip this check.
-	*/
+	/*
+	 * For exec-only memory, we do not know the pkey in
+	 * advance, so skip this check.
+	 */
 	if (pkey != UNKNOWN_PKEY)
 		pkey_assert(last_si_pkey == pkey);
 
@@ -1335,6 +1335,49 @@ 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();
+	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();
+}
+
 void test_mprotect_pkey_on_unsupported_cpu(int *ptr, u16 pkey)
 {
 	int size = PAGE_SIZE;
_

  parent reply	other threads:[~2018-03-26 17:29 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-03-26 17:27 [PATCH 0/9] [v2] x86, pkeys: two protection keys bug fixes Dave Hansen
2018-03-26 17:27 ` [PATCH 1/9] x86, pkeys: do not special case protection key 0 Dave Hansen
2018-03-26 17:47   ` Shuah Khan
2018-03-26 17:53     ` Dave Hansen
2018-03-26 17:58       ` Shuah Khan
2018-03-26 17:27 ` [PATCH 2/9] x86, pkeys, selftests: save off 'prot' for allocations Dave Hansen
2018-03-26 17:27 ` [PATCH 3/9] x86, pkeys, selftests: add a test for pkey 0 Dave Hansen
2018-03-26 17:27 ` [PATCH 4/9] x86, pkeys: override pkey when moving away from PROT_EXEC Dave Hansen
2018-04-07  0:09   ` Ram Pai
2018-04-07  0:47     ` Dave Hansen
2018-04-07  1:09       ` Ram Pai
2018-04-26 17:57         ` Dave Hansen
2018-04-30  7:51           ` Ram Pai
2018-04-30 16:36             ` Dave Hansen
2018-04-25 22:10   ` Shakeel Butt
2018-04-26  8:55     ` Thomas Gleixner
2018-04-26 18:17       ` Dave Hansen
2018-03-26 17:27 ` [PATCH 5/9] x86, pkeys, selftests: fix pointer math Dave Hansen
2018-03-26 17:27 ` [PATCH 6/9] x86, pkeys, selftests: fix pkey exhaustion test off-by-one Dave Hansen
2018-03-26 17:27 ` [PATCH 7/9] x86, pkeys, selftests: factor out "instruction page" Dave Hansen
2018-03-26 17:27 ` [PATCH 8/9] x86, pkeys, selftests: add allow faults on unknown keys Dave Hansen
2018-03-26 17:27 ` Dave Hansen [this message]
  -- strict thread matches above, loose matches on Subject: below --
2018-04-27 17:45 [PATCH 0/9] [v3] x86, pkeys: two protection keys bug fixes Dave Hansen
2018-04-27 17:45 ` [PATCH 9/9] x86, pkeys, selftests: add PROT_EXEC test Dave Hansen
2018-03-23 18:09 [PATCH 0/9] x86, pkeys: two protection keys bug fixes Dave Hansen
2018-03-23 18:09 ` [PATCH 9/9] x86, pkeys, selftests: add PROT_EXEC test Dave Hansen

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