kselftest: vm: add tests for memory-deny-write-execute

Add some tests to cover the new PR_SET_MDWE prctl.

Link: https://lkml.kernel.org/r/20230119160344.54358-3-joey.gouly@arm.com
Co-developed-by: Joey Gouly <joey.gouly@arm.com>
Signed-off-by: Joey Gouly <joey.gouly@arm.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Jeremy Linton <jeremy.linton@arm.com>
Cc: Lennart Poettering <lennart@poettering.net>
Cc: Mark Brown <broonie@kernel.org>
Cc: nd <nd@arm.com>
Cc: Szabolcs Nagy <szabolcs.nagy@arm.com>
Cc: Topi Miettinen <toiwoton@gmail.com>
Cc: Zbigniew Jędrzejewski-Szmek <zbyszek@in.waw.pl>
Cc: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/tools/testing/selftests/mm/Makefile b/tools/testing/selftests/mm/Makefile
index 0a44d77..d90cdc0 100644 (file)
--- a/tools/testing/selftests/mm/Makefile
+++ b/tools/testing/selftests/mm/Makefile
@@ -60,6 +60,7 @@ TEST_GEN_PROGS += soft-dirty
 TEST_GEN_PROGS += split_huge_page_test
 TEST_GEN_FILES += ksm_tests
 TEST_GEN_PROGS += ksm_functional_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/mm/mdwe_test.c b/tools/testing/selftests/mm/mdwe_test.c
new file mode 100644 (file)
index 0000000..f466a09
--- /dev/null
+++ b/tools/testing/selftests/mm/mdwe_test.c
@@ -0,0 +1,197 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#ifdef __aarch64__
+#include <asm/hwcap.h>
+#endif
+
+#include <linux/mman.h>
+#include <linux/prctl.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/auxv.h>
+#include <sys/prctl.h>
+#include <sys/wait.h>
+#include <unistd.h>
+
+#include "../kselftest_harness.h"
+
+#ifndef __aarch64__
+# define PROT_BTI      0
+#endif
+
+TEST(prctl_flags)
+{
+       EXPECT_LT(prctl(PR_SET_MDWE, 7L, 0L, 0L, 0L), 0);
+       EXPECT_LT(prctl(PR_SET_MDWE, 0L, 7L, 0L, 0L), 0);
+       EXPECT_LT(prctl(PR_SET_MDWE, 0L, 0L, 7L, 0L), 0);
+       EXPECT_LT(prctl(PR_SET_MDWE, 0L, 0L, 0L, 7L), 0);
+
+       EXPECT_LT(prctl(PR_GET_MDWE, 7L, 0L, 0L, 0L), 0);
+       EXPECT_LT(prctl(PR_GET_MDWE, 0L, 7L, 0L, 0L), 0);
+       EXPECT_LT(prctl(PR_GET_MDWE, 0L, 0L, 7L, 0L), 0);
+       EXPECT_LT(prctl(PR_GET_MDWE, 0L, 0L, 0L, 7L), 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_REFUSE_EXEC_GAIN, 0L, 0L, 0L);
+       ASSERT_EQ(ret, 0) {
+               TH_LOG("PR_SET_MDWE failed or unsupported");
+       }
+
+       ret = prctl(PR_GET_MDWE, 0L, 0L, 0L, 0L);
+       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, *p2;
+
+       p2 = mmap(NULL, self->size, PROT_READ | PROT_EXEC, self->flags, 0, 0);
+       self->p = mmap(NULL, self->size, PROT_READ, self->flags, 0, 0);
+       ASSERT_NE(self->p, MAP_FAILED);
+
+       p = mmap(self->p + self->size, 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