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[198.145.64.163]) by smtp.gmail.com with ESMTPSA id u35-20020a632363000000b0046f6d7dcd1dsm1580328pgm.25.2022.10.28.13.16.44 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 28 Oct 2022 13:16:44 -0700 (PDT) Date: Fri, 28 Oct 2022 13:16:43 -0700 From: Kees Cook To: Joey Gouly Cc: Catalin Marinas , Andrew Morton , Lennart Poettering , Zbigniew =?utf-8?Q?J=C4=99drzejewski-Szmek?= , Alexander Viro , Szabolcs Nagy , Mark Brown , Jeremy Linton , Topi Miettinen , linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-abi-devel@lists.sourceforge.net, nd@arm.com, shuah@kernel.org Subject: Re: [PATCH v1 2/2] kselftest: vm: add tests for memory-deny-write-execute Message-ID: <202210281314.C5D3414722@keescook> References: <20221026150457.36957-1-joey.gouly@arm.com> <20221026150457.36957-3-joey.gouly@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20221026150457.36957-3-joey.gouly@arm.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Here's an alternative rewritten to use kselftest_harness.h, with tests for the prctl() flags, and the missed Makefile addition. This should be much easier to add more variants and tests to, I hope. -Kees >From bc442a99ebd9852bfaa7444b521bd55fdbb4d369 Mon Sep 17 00:00:00 2001 From: Kees Cook Date: Fri, 28 Oct 2022 13:10:45 -0700 Subject: [PATCH] selftests/vm: add tests for memory-deny-write-execute Add tests for new prctl() commands, including flag values. Add tests for new denials based on PROT_EXEC across mmap() and mprotect() with MDWE. Co-developed-by: Joey Gouly Signed-off-by: Joey Gouly Signed-off-by: Kees Cook --- tools/testing/selftests/vm/Makefile | 1 + tools/testing/selftests/vm/mdwe_test.c | 201 +++++++++++++++++++++++++ 2 files changed, 202 insertions(+) create mode 100644 tools/testing/selftests/vm/mdwe_test.c diff --git a/tools/testing/selftests/vm/Makefile b/tools/testing/selftests/vm/Makefile index 163c2fde3cb3..8dd4d4910fa5 100644 --- a/tools/testing/selftests/vm/Makefile +++ b/tools/testing/selftests/vm/Makefile @@ -52,6 +52,7 @@ TEST_GEN_FILES += userfaultfd TEST_GEN_PROGS += soft-dirty TEST_GEN_PROGS += split_huge_page_test TEST_GEN_FILES += ksm_tests +TEST_GEN_PROGS += mdwe_test ifeq ($(MACHINE),x86_64) CAN_BUILD_I386 := $(shell ./../x86/check_cc.sh "$(CC)" ../x86/trivial_32bit_program.c -m32) diff --git a/tools/testing/selftests/vm/mdwe_test.c b/tools/testing/selftests/vm/mdwe_test.c new file mode 100644 index 000000000000..d6f6b751bcd6 --- /dev/null +++ b/tools/testing/selftests/vm/mdwe_test.c @@ -0,0 +1,201 @@ +// SPDX-License-Identifier: GPL-2.0 +#ifdef __aarch64__ +#include +#endif +#include +#include +#include +#include +#include +#include +#include + +#include + +#include "../kselftest_harness.h" + +#define PR_SET_MDWE 65 +# define PR_MDWE_FLAG_MMAP 1 + +#define PR_GET_MDWE 66 + +#ifdef __aarch64__ +# define PROT_BTI 0x10 /* BTI guarded page */ +#else +# define PROT_BTI 0 +#endif + +TEST(prctl_flags) +{ + EXPECT_LT(prctl(PR_SET_MDWE, 7, 0, 0, 0), 0); + EXPECT_LT(prctl(PR_SET_MDWE, 0, 7, 0, 0), 0); + EXPECT_LT(prctl(PR_SET_MDWE, 0, 0, 7, 0), 0); + EXPECT_LT(prctl(PR_SET_MDWE, 0, 0, 0, 7), 0); + + EXPECT_LT(prctl(PR_GET_MDWE, 7, 0, 0, 0), 0); + EXPECT_LT(prctl(PR_GET_MDWE, 0, 7, 0, 0), 0); + EXPECT_LT(prctl(PR_GET_MDWE, 0, 0, 7, 0), 0); + EXPECT_LT(prctl(PR_GET_MDWE, 0, 0, 0, 7), 0); +} + +FIXTURE(mdwe) +{ + void *p; + int flags; + size_t size; + pid_t pid; +}; + +FIXTURE_VARIANT(mdwe) +{ + bool enabled; + bool forked; +}; + +FIXTURE_VARIANT_ADD(mdwe, stock) +{ + .enabled = false, + .forked = false, +}; + +FIXTURE_VARIANT_ADD(mdwe, enabled) +{ + .enabled = true, + .forked = false, +}; + +FIXTURE_VARIANT_ADD(mdwe, forked) +{ + .enabled = true, + .forked = true, +}; + +FIXTURE_SETUP(mdwe) +{ + int ret, status; + + self->p = NULL; + self->flags = MAP_SHARED | MAP_ANONYMOUS; + self->size = getpagesize(); + + if (!variant->enabled) + return; + + ret = prctl(PR_SET_MDWE, PR_MDWE_FLAG_MMAP, 0, 0, 0); + ASSERT_EQ(ret, 0) { + TH_LOG("PR_SET_MDWE failed or unsupported"); + } + + ret = prctl(PR_GET_MDWE, 0, 0, 0, 0); + ASSERT_EQ(ret, 1); + + if (variant->forked) { + self->pid = fork(); + ASSERT_GE(self->pid, 0) { + TH_LOG("fork failed\n"); + } + + if (self->pid > 0) { + ret = waitpid(self->pid, &status, 0); + ASSERT_TRUE(WIFEXITED(status)); + exit(WEXITSTATUS(status)); + } + } +} + +FIXTURE_TEARDOWN(mdwe) +{ + if (self->p && self->p != MAP_FAILED) + munmap(self->p, self->size); +} + +TEST_F(mdwe, mmap_READ_EXEC) +{ + self->p = mmap(NULL, self->size, PROT_READ | PROT_EXEC, self->flags, 0, 0); + EXPECT_NE(self->p, MAP_FAILED); +} + +TEST_F(mdwe, mmap_WRITE_EXEC) +{ + self->p = mmap(NULL, self->size, PROT_WRITE | PROT_EXEC, self->flags, 0, 0); + if (variant->enabled) { + EXPECT_EQ(self->p, MAP_FAILED); + } else { + EXPECT_NE(self->p, MAP_FAILED); + } +} + +TEST_F(mdwe, mprotect_stay_EXEC) +{ + int ret; + + self->p = mmap(NULL, self->size, PROT_READ | PROT_EXEC, self->flags, 0, 0); + ASSERT_NE(self->p, MAP_FAILED); + + ret = mprotect(self->p, self->size, PROT_READ | PROT_EXEC); + EXPECT_EQ(ret, 0); +} + +TEST_F(mdwe, mprotect_add_EXEC) +{ + int ret; + + self->p = mmap(NULL, self->size, PROT_READ, self->flags, 0, 0); + ASSERT_NE(self->p, MAP_FAILED); + + ret = mprotect(self->p, self->size, PROT_READ | PROT_EXEC); + if (variant->enabled) { + EXPECT_LT(ret, 0); + } else { + EXPECT_EQ(ret, 0); + } +} + +TEST_F(mdwe, mprotect_WRITE_EXEC) +{ + int ret; + + self->p = mmap(NULL, self->size, PROT_WRITE, self->flags, 0, 0); + ASSERT_NE(self->p, MAP_FAILED); + + ret = mprotect(self->p, self->size, PROT_WRITE | PROT_EXEC); + if (variant->enabled) { + EXPECT_LT(ret, 0); + } else { + EXPECT_EQ(ret, 0); + } +} + +TEST_F(mdwe, mmap_FIXED) +{ + void *p; + + self->p = mmap(NULL, self->size, PROT_READ, self->flags, 0, 0); + ASSERT_NE(self->p, MAP_FAILED); + + p = mmap(self->p, self->size, PROT_READ | PROT_EXEC, + self->flags | MAP_FIXED, 0, 0); + if (variant->enabled) { + EXPECT_EQ(p, MAP_FAILED); + } else { + EXPECT_EQ(p, self->p); + } +} + +TEST_F(mdwe, arm64_BTI) +{ + int ret; + +#ifdef __aarch64__ + if (!(getauxval(AT_HWCAP2) & HWCAP2_BTI)) +#endif + SKIP(return, "HWCAP2_BTI not supported"); + + self->p = mmap(NULL, self->size, PROT_EXEC, self->flags, 0, 0); + ASSERT_NE(self->p, MAP_FAILED); + + ret = mprotect(self->p, self->size, PROT_EXEC | PROT_BTI); + EXPECT_EQ(ret, 0); +} + +TEST_HARNESS_MAIN -- 2.34.1 -- Kees Cook