kselftest/arm64: Check forked child mte memory accessibility

This test covers the mte memory behaviour of the forked process with
different mapping properties and flags. It checks that all bytes of
forked child memory are accessible with the same tag as that of the
parent and memory accessed outside the tag range causes fault to
occur.
Co-developed-by: Gabor Kertesz <gabor.kertesz@arm.com>
Signed-off-by: Gabor Kertesz <gabor.kertesz@arm.com>
Signed-off-by: Amit Daniel Kachhap <amit.kachhap@arm.com>
Tested-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20201002115630.24683-4-amit.kachhap@arm.comSigned-off-by: Will Deacon <will@kernel.org>

tools/testing/selftests/arm64/mte/.gitignore

 check_buffer_fill
 check_tags_inclusion
+check_child_memory

tools/testing/selftests/arm64/mte/check_child_memory.c

+// SPDX-License-Identifier: GPL-2.0
+// Copyright (C) 2020 ARM Limited
+
+#define _GNU_SOURCE
+
+#include <errno.h>
+#include <signal.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <ucontext.h>
+#include <sys/wait.h>
+
+#include "kselftest.h"
+#include "mte_common_util.h"
+#include "mte_def.h"
+
+#define BUFFER_SIZE		(5 * MT_GRANULE_SIZE)
+#define RUNS			(MT_TAG_COUNT)
+#define UNDERFLOW		MT_GRANULE_SIZE
+#define OVERFLOW		MT_GRANULE_SIZE
+
+static size_t page_size;
+static int sizes[] = {
+	1, 537, 989, 1269, MT_GRANULE_SIZE - 1, MT_GRANULE_SIZE,
+	/* page size - 1*/ 0, /* page_size */ 0, /* page size + 1 */ 0
+};
+
+static int check_child_tag_inheritance(char *ptr, int size, int mode)
+{
+	int i, parent_tag, child_tag, fault, child_status;
+	pid_t child;
+
+	parent_tag = MT_FETCH_TAG((uintptr_t)ptr);
+	fault = 0;
+
+	child = fork();
+	if (child == -1) {
+		ksft_print_msg("FAIL: child process creation\n");
+		return KSFT_FAIL;
+	} else if (child == 0) {
+		mte_initialize_current_context(mode, (uintptr_t)ptr, size);
+		/* Do copy on write */
+		memset(ptr, '1', size);
+		mte_wait_after_trig();
+		if (cur_mte_cxt.fault_valid == true) {
+			fault = 1;
+			goto check_child_tag_inheritance_err;
+		}
+		for (i = 0 ; i < size ; i += MT_GRANULE_SIZE) {
+			child_tag = MT_FETCH_TAG((uintptr_t)(mte_get_tag_address(ptr + i)));
+			if (parent_tag != child_tag) {
+				ksft_print_msg("FAIL: child mte tag mismatch\n");
+				fault = 1;
+				goto check_child_tag_inheritance_err;
+			}
+		}
+		mte_initialize_current_context(mode, (uintptr_t)ptr, -UNDERFLOW);
+		memset(ptr - UNDERFLOW, '2', UNDERFLOW);
+		mte_wait_after_trig();
+		if (cur_mte_cxt.fault_valid == false) {
+			fault = 1;
+			goto check_child_tag_inheritance_err;
+		}
+		mte_initialize_current_context(mode, (uintptr_t)ptr, size + OVERFLOW);
+		memset(ptr + size, '3', OVERFLOW);
+		mte_wait_after_trig();
+		if (cur_mte_cxt.fault_valid == false) {
+			fault = 1;
+			goto check_child_tag_inheritance_err;
+		}
+check_child_tag_inheritance_err:
+		_exit(fault);
+	}
+	/* Wait for child process to terminate */
+	wait(&child_status);
+	if (WIFEXITED(child_status))
+		fault = WEXITSTATUS(child_status);
+	else
+		fault = 1;
+	return (fault) ? KSFT_FAIL : KSFT_PASS;
+}
+
+static int check_child_memory_mapping(int mem_type, int mode, int mapping)
+{
+	char *ptr;
+	int run, result;
+	int item = sizeof(sizes)/sizeof(int);
+
+	item = sizeof(sizes)/sizeof(int);
+	mte_switch_mode(mode, MTE_ALLOW_NON_ZERO_TAG);
+	for (run = 0; run < item; run++) {
+		ptr = (char *)mte_allocate_memory_tag_range(sizes[run], mem_type, mapping,
+							    UNDERFLOW, OVERFLOW);
+		if (check_allocated_memory_range(ptr, sizes[run], mem_type,
+						 UNDERFLOW, OVERFLOW) != KSFT_PASS)
+			return KSFT_FAIL;
+		result = check_child_tag_inheritance(ptr, sizes[run], mode);
+		mte_free_memory_tag_range((void *)ptr, sizes[run], mem_type, UNDERFLOW, OVERFLOW);
+		if (result == KSFT_FAIL)
+			return result;
+	}
+	return KSFT_PASS;
+}
+
+static int check_child_file_mapping(int mem_type, int mode, int mapping)
+{
+	char *ptr, *map_ptr;
+	int run, fd, map_size, result = KSFT_PASS;
+	int total = sizeof(sizes)/sizeof(int);
+
+	mte_switch_mode(mode, MTE_ALLOW_NON_ZERO_TAG);
+	for (run = 0; run < total; run++) {
+		fd = create_temp_file();
+		if (fd == -1)
+			return KSFT_FAIL;
+
+		map_size = sizes[run] + OVERFLOW + UNDERFLOW;
+		map_ptr = (char *)mte_allocate_file_memory(map_size, mem_type, mapping, false, fd);
+		if (check_allocated_memory(map_ptr, map_size, mem_type, false) != KSFT_PASS) {
+			close(fd);
+			return KSFT_FAIL;
+		}
+		ptr = map_ptr + UNDERFLOW;
+		mte_initialize_current_context(mode, (uintptr_t)ptr, sizes[run]);
+		/* Only mte enabled memory will allow tag insertion */
+		ptr = mte_insert_tags((void *)ptr, sizes[run]);
+		if (!ptr || cur_mte_cxt.fault_valid == true) {
+			ksft_print_msg("FAIL: Insert tags on file based memory\n");
+			munmap((void *)map_ptr, map_size);
+			close(fd);
+			return KSFT_FAIL;
+		}
+		result = check_child_tag_inheritance(ptr, sizes[run], mode);
+		mte_clear_tags((void *)ptr, sizes[run]);
+		munmap((void *)map_ptr, map_size);
+		close(fd);
+		if (result != KSFT_PASS)
+			return KSFT_FAIL;
+	}
+	return KSFT_PASS;
+}
+
+int main(int argc, char *argv[])
+{
+	int err;
+	int item = sizeof(sizes)/sizeof(int);
+
+	page_size = getpagesize();
+	if (!page_size) {
+		ksft_print_msg("ERR: Unable to get page size\n");
+		return KSFT_FAIL;
+	}
+	sizes[item - 3] = page_size - 1;
+	sizes[item - 2] = page_size;
+	sizes[item - 1] = page_size + 1;
+
+	err = mte_default_setup();
+	if (err)
+		return err;
+
+	/* Register SIGSEGV handler */
+	mte_register_signal(SIGSEGV, mte_default_handler);
+	mte_register_signal(SIGBUS, mte_default_handler);
+
+	evaluate_test(check_child_memory_mapping(USE_MMAP, MTE_SYNC_ERR, MAP_PRIVATE),
+		"Check child anonymous memory with private mapping, precise mode and mmap memory\n");
+	evaluate_test(check_child_memory_mapping(USE_MMAP, MTE_SYNC_ERR, MAP_SHARED),
+		"Check child anonymous memory with shared mapping, precise mode and mmap memory\n");
+	evaluate_test(check_child_memory_mapping(USE_MMAP, MTE_ASYNC_ERR, MAP_PRIVATE),
+		"Check child anonymous memory with private mapping, imprecise mode and mmap memory\n");
+	evaluate_test(check_child_memory_mapping(USE_MMAP, MTE_ASYNC_ERR, MAP_SHARED),
+		"Check child anonymous memory with shared mapping, imprecise mode and mmap memory\n");
+	evaluate_test(check_child_memory_mapping(USE_MPROTECT, MTE_SYNC_ERR, MAP_PRIVATE),
+		"Check child anonymous memory with private mapping, precise mode and mmap/mprotect memory\n");
+	evaluate_test(check_child_memory_mapping(USE_MPROTECT, MTE_SYNC_ERR, MAP_SHARED),
+		"Check child anonymous memory with shared mapping, precise mode and mmap/mprotect memory\n");
+
+	evaluate_test(check_child_file_mapping(USE_MMAP, MTE_SYNC_ERR, MAP_PRIVATE),
+		"Check child file memory with private mapping, precise mode and mmap memory\n");
+	evaluate_test(check_child_file_mapping(USE_MMAP, MTE_SYNC_ERR, MAP_SHARED),
+		"Check child file memory with shared mapping, precise mode and mmap memory\n");
+	evaluate_test(check_child_memory_mapping(USE_MMAP, MTE_ASYNC_ERR, MAP_PRIVATE),
+		"Check child file memory with private mapping, imprecise mode and mmap memory\n");
+	evaluate_test(check_child_memory_mapping(USE_MMAP, MTE_ASYNC_ERR, MAP_SHARED),
+		"Check child file memory with shared mapping, imprecise mode and mmap memory\n");
+	evaluate_test(check_child_memory_mapping(USE_MPROTECT, MTE_SYNC_ERR, MAP_PRIVATE),
+		"Check child file memory with private mapping, precise mode and mmap/mprotect memory\n");
+	evaluate_test(check_child_memory_mapping(USE_MPROTECT, MTE_SYNC_ERR, MAP_SHARED),
+		"Check child file memory with shared mapping, precise mode and mmap/mprotect memory\n");
+
+	mte_restore_setup();
+	ksft_print_cnts();
+	return ksft_get_fail_cnt() == 0 ? KSFT_PASS : KSFT_FAIL;
+}