kselftests/arm64: add PAuth test for whether exec() changes keys (806a15b2) · Commits · 戴 / test

tools/testing/selftests/arm64/pauth/Makefile

+4 −0

Original line number	Diff line number	Diff line
		@@ -13,6 +13,7 @@ pauth_cc_support := $(shell if ($(CC) $(CFLAGS) -march=armv8.3-a -E -x c /dev/nu
		ifeq ($(pauth_cc_support),1)
		TEST_GEN_PROGS := pac
		TEST_GEN_FILES := pac_corruptor.o helper.o
		TEST_GEN_PROGS_EXTENDED := exec_target
		endif

		include ../../lib.mk
		@@ -30,6 +31,9 @@ $(OUTPUT)/helper.o: helper.c
		# greater, gcc emits pac* instructions which are not in HINT NOP space,
		# preventing the tests from occurring at all. Compile for ARMv8.2 so tests can
		# run on earlier targets and print a meaningful error messages
		$(OUTPUT)/exec_target: exec_target.c $(OUTPUT)/helper.o
		$(CC) $^ -o $@ $(CFLAGS) -march=armv8.2-a

		$(OUTPUT)/pac: pac.c $(OUTPUT)/pac_corruptor.o $(OUTPUT)/helper.o
		$(CC) $^ -o $@ $(CFLAGS) -march=armv8.2-a
		endif

tools/testing/selftests/arm64/pauth/exec_target.c

0 → 100644

+34 −0

Original line number	Diff line number	Diff line
		// SPDX-License-Identifier: GPL-2.0
		// Copyright (C) 2020 ARM Limited

		#include <stdio.h>
		#include <stdlib.h>
		#include <sys/auxv.h>

		#include "helper.h"

		int main(void)
		{
		struct signatures signed_vals;
		unsigned long hwcaps;
		size_t val;

		fread(&val, sizeof(size_t), 1, stdin);

		/* don't try to execute illegal (unimplemented) instructions) caller
		* should have checked this and keep worker simple
		*/
		hwcaps = getauxval(AT_HWCAP);

		if (hwcaps & HWCAP_PACA) {
		signed_vals.keyia = keyia_sign(val);
		signed_vals.keyib = keyib_sign(val);
		signed_vals.keyda = keyda_sign(val);
		signed_vals.keydb = keydb_sign(val);
		}
		signed_vals.keyg = (hwcaps & HWCAP_PACG) ? keyg_sign(val) : 0;

		fwrite(&signed_vals, sizeof(struct signatures), 1, stdout);

		return 0;
		}

tools/testing/selftests/arm64/pauth/helper.h

+10 −0

Original line number	Diff line number	Diff line
		@@ -6,6 +6,16 @@

		#include <stdlib.h>

		#define NKEYS 5

		struct signatures {
		size_t keyia;
		size_t keyib;
		size_t keyda;
		size_t keydb;
		size_t keyg;
		};

		void pac_corruptor(void);

		/* PAuth sign a value with key ia and modifier value 0 */

tools/testing/selftests/arm64/pauth/pac.c

+150 −0

Original line number	Diff line number	Diff line
		@@ -2,6 +2,8 @@
		// Copyright (C) 2020 ARM Limited

		#include <sys/auxv.h>
		#include <sys/types.h>
		#include <sys/wait.h>
		#include <signal.h>
		#include <setjmp.h>

		@@ -28,6 +30,117 @@ do { \
		ASSERT_NE(0, hwcaps & HWCAP_PACG) TH_LOG("Generic PAUTH not enabled"); \
		} while (0)

		void sign_specific(struct signatures *sign, size_t val)
		{
		sign->keyia = keyia_sign(val);
		sign->keyib = keyib_sign(val);
		sign->keyda = keyda_sign(val);
		sign->keydb = keydb_sign(val);
		}

		void sign_all(struct signatures *sign, size_t val)
		{
		sign->keyia = keyia_sign(val);
		sign->keyib = keyib_sign(val);
		sign->keyda = keyda_sign(val);
		sign->keydb = keydb_sign(val);
		sign->keyg = keyg_sign(val);
		}

		int n_same(struct signatures old, struct signatures new, int nkeys)
		{
		int res = 0;

		res += old->keyia == new->keyia;
		res += old->keyib == new->keyib;
		res += old->keyda == new->keyda;
		res += old->keydb == new->keydb;
		if (nkeys == NKEYS)
		res += old->keyg == new->keyg;

		return res;
		}

		int exec_sign_all(struct signatures *signed_vals, size_t val)
		{
		int new_stdin[2];
		int new_stdout[2];
		int status;
		ssize_t ret;
		pid_t pid;

		ret = pipe(new_stdin);
		if (ret == -1) {
		perror("pipe returned error");
		return -1;
		}

		ret = pipe(new_stdout);
		if (ret == -1) {
		perror("pipe returned error");
		return -1;
		}

		pid = fork();
		// child
		if (pid == 0) {
		dup2(new_stdin[0], STDIN_FILENO);
		if (ret == -1) {
		perror("dup2 returned error");
		exit(1);
		}

		dup2(new_stdout[1], STDOUT_FILENO);
		if (ret == -1) {
		perror("dup2 returned error");
		exit(1);
		}

		close(new_stdin[0]);
		close(new_stdin[1]);
		close(new_stdout[0]);
		close(new_stdout[1]);

		ret = execl("exec_target", "exec_target", (char *)NULL);
		if (ret == -1) {
		perror("exec returned error");
		exit(1);
		}
		}

		close(new_stdin[0]);
		close(new_stdout[1]);

		ret = write(new_stdin[1], &val, sizeof(size_t));
		if (ret == -1) {
		perror("write returned error");
		return -1;
		}

		/*
		* wait for the worker to finish, so that read() reads all data
		* will also context switch with worker so that this function can be used
		* for context switch tests
		*/
		waitpid(pid, &status, 0);
		if (WIFEXITED(status) == 0) {
		fprintf(stderr, "worker exited unexpectedly\n");
		return -1;
		}
		if (WEXITSTATUS(status) != 0) {
		fprintf(stderr, "worker exited with error\n");
		return -1;
		}

		ret = read(new_stdout[0], signed_vals, sizeof(struct signatures));
		if (ret == -1) {
		perror("read returned error");
		return -1;
		}

		return 0;
		}

		sigjmp_buf jmpbuf;
		void pac_signal_handler(int signum, siginfo_t si, void uc)
		{
		@@ -92,4 +205,41 @@ TEST(pac_instructions_not_nop_generic)
		ASSERT_NE(0, keyg) TH_LOG("keyg instructions did nothing");
		}

		/*
		* fork() does not change keys. Only exec() does so call a worker program.
		* Its only job is to sign a value and report back the resutls
		*/
		TEST(exec_changed_keys)
		{
		struct signatures new_keys;
		struct signatures old_keys;
		int ret;
		int same = 10;
		int nkeys = NKEYS;
		unsigned long hwcaps = getauxval(AT_HWCAP);

		/* generic and data key instructions are not in NOP space. This prevents a SIGILL */
		ASSERT_NE(0, hwcaps & HWCAP_PACA) TH_LOG("PAUTH not enabled");
		if (!(hwcaps & HWCAP_PACG)) {
		TH_LOG("WARNING: Generic PAUTH not enabled. Skipping generic key checks");
		nkeys = NKEYS - 1;
		}

		for (int i = 0; i < PAC_COLLISION_ATTEMPTS; i++) {
		ret = exec_sign_all(&new_keys, i);
		ASSERT_EQ(0, ret) TH_LOG("failed to run worker");

		if (nkeys == NKEYS)
		sign_all(&old_keys, i);
		else
		sign_specific(&old_keys, i);

		ret = n_same(&old_keys, &new_keys, nkeys);
		if (ret < same)
		same = ret;
		}

		ASSERT_EQ(0, same) TH_LOG("exec() did not change %d keys", same);
		}

		TEST_HARNESS_MAIN

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