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