Commit 4dafc08d authored by Amit Kachhap's avatar Amit Kachhap Committed by Will Deacon
Browse files

kselftest/arm64: Check mte tagged user address in kernel



Add a testcase to check that user address with valid/invalid
mte tag works in kernel mode. This test verifies that the kernel
API's __arch_copy_from_user/__arch_copy_to_user works by considering
if the user pointer has valid/invalid allocation tags.

In MTE sync mode, file memory read/write and other similar interfaces
fails if a user memory with invalid tag is accessed in kernel. In async
mode no such failure occurs.
Signed-off-by: Amit Kachhap's avatarAmit Daniel Kachhap <amit.kachhap@arm.com>
Tested-by: Catalin Marinas's avatarCatalin Marinas <catalin.marinas@arm.com>
Acked-by: Catalin Marinas's avatarCatalin 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/20201002115630.24683-7-amit.kachhap@arm.com

Signed-off-by: default avatarWill Deacon <will@kernel.org>
parent f981d8fa
......@@ -3,3 +3,4 @@ check_tags_inclusion
check_child_memory
check_mmap_options
check_ksm_options
check_user_mem
// SPDX-License-Identifier: GPL-2.0
// Copyright (C) 2020 ARM Limited
#define _GNU_SOURCE
#include <errno.h>
#include <fcntl.h>
#include <signal.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <ucontext.h>
#include <unistd.h>
#include <sys/mman.h>
#include "kselftest.h"
#include "mte_common_util.h"
#include "mte_def.h"
static size_t page_sz;
static int check_usermem_access_fault(int mem_type, int mode, int mapping)
{
int fd, i, err;
char val = 'A';
size_t len, read_len;
void *ptr, *ptr_next;
err = KSFT_FAIL;
len = 2 * page_sz;
mte_switch_mode(mode, MTE_ALLOW_NON_ZERO_TAG);
fd = create_temp_file();
if (fd == -1)
return KSFT_FAIL;
for (i = 0; i < len; i++)
write(fd, &val, sizeof(val));
lseek(fd, 0, 0);
ptr = mte_allocate_memory(len, mem_type, mapping, true);
if (check_allocated_memory(ptr, len, mem_type, true) != KSFT_PASS) {
close(fd);
return KSFT_FAIL;
}
mte_initialize_current_context(mode, (uintptr_t)ptr, len);
/* Copy from file into buffer with valid tag */
read_len = read(fd, ptr, len);
mte_wait_after_trig();
if (cur_mte_cxt.fault_valid || read_len < len)
goto usermem_acc_err;
/* Verify same pattern is read */
for (i = 0; i < len; i++)
if (*(char *)(ptr + i) != val)
break;
if (i < len)
goto usermem_acc_err;
/* Tag the next half of memory with different value */
ptr_next = (void *)((unsigned long)ptr + page_sz);
ptr_next = mte_insert_new_tag(ptr_next);
mte_set_tag_address_range(ptr_next, page_sz);
lseek(fd, 0, 0);
/* Copy from file into buffer with invalid tag */
read_len = read(fd, ptr, len);
mte_wait_after_trig();
/*
* Accessing user memory in kernel with invalid tag should fail in sync
* mode without fault but may not fail in async mode as per the
* implemented MTE userspace support in Arm64 kernel.
*/
if (mode == MTE_SYNC_ERR &&
!cur_mte_cxt.fault_valid && read_len < len) {
err = KSFT_PASS;
} else if (mode == MTE_ASYNC_ERR &&
!cur_mte_cxt.fault_valid && read_len == len) {
err = KSFT_PASS;
}
usermem_acc_err:
mte_free_memory((void *)ptr, len, mem_type, true);
close(fd);
return err;
}
int main(int argc, char *argv[])
{
int err;
page_sz = getpagesize();
if (!page_sz) {
ksft_print_msg("ERR: Unable to get page size\n");
return KSFT_FAIL;
}
err = mte_default_setup();
if (err)
return err;
/* Register signal handlers */
mte_register_signal(SIGSEGV, mte_default_handler);
evaluate_test(check_usermem_access_fault(USE_MMAP, MTE_SYNC_ERR, MAP_PRIVATE),
"Check memory access from kernel in sync mode, private mapping and mmap memory\n");
evaluate_test(check_usermem_access_fault(USE_MMAP, MTE_SYNC_ERR, MAP_SHARED),
"Check memory access from kernel in sync mode, shared mapping and mmap memory\n");
evaluate_test(check_usermem_access_fault(USE_MMAP, MTE_ASYNC_ERR, MAP_PRIVATE),
"Check memory access from kernel in async mode, private mapping and mmap memory\n");
evaluate_test(check_usermem_access_fault(USE_MMAP, MTE_ASYNC_ERR, MAP_SHARED),
"Check memory access from kernel in async mode, shared mapping and mmap memory\n");
mte_restore_setup();
ksft_print_cnts();
return ksft_get_fail_cnt() == 0 ? KSFT_PASS : KSFT_FAIL;
}
......@@ -64,6 +64,7 @@ int create_temp_file(void);
/* Assembly MTE utility functions */
void *mte_insert_random_tag(void *ptr);
void *mte_insert_new_tag(void *ptr);
void *mte_get_tag_address(void *ptr);
void mte_set_tag_address_range(void *ptr, int range);
void mte_clear_tag_address_range(void *ptr, int range);
......
......@@ -26,6 +26,20 @@ ENTRY(mte_insert_random_tag)
ret
ENDPROC(mte_insert_random_tag)
/*
* mte_insert_new_tag: Insert new tag and different from the source tag if
* source pointer has it.
* Input:
* x0 - source pointer with a tag/no-tag
* Return:
* x0 - pointer with random tag
*/
ENTRY(mte_insert_new_tag)
gmi x1, x0, xzr
irg x0, x0, x1
ret
ENDPROC(mte_insert_new_tag)
/*
* mte_get_tag_address: Get the tag from given address.
* Input:
......
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