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Commit 6af17cf8 authored by Dave Hansen's avatar Dave Hansen Committed by Ingo Molnar
Browse files

x86/pkeys/selftests: Add PROT_EXEC test 



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: default avatarDave 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: default avatarIngo Molnar <mingo@kernel.org>
parent 3fcd2b2d

tools/testing/selftests/x86/protection_keys.c

+44 −0
Original line number Diff line number Diff line
@@ -1303,6 +1303,49 @@ void test_executing_on_unreadable_memory(int *ptr, u16 pkey) 
	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,