jcs.org
Serenity Operating System
1/*
2 * Copyright (c) 2018-2022, Andreas Kling <kling@serenityos.org>
3 * Copyright (c) 2021, Andrew Kaster <akaster@serenityos.org>
4 *
5 * SPDX-License-Identifier: BSD-2-Clause
6 */
7
8#include <AK/Assertions.h>
9#include <AK/Format.h>
10#include <AK/Types.h>
11#include <LibTest/TestCase.h>
12#include <errno.h>
13#include <fcntl.h>
14#include <stdio.h>
15#include <sys/mman.h>
16#include <unistd.h>
17
18#define EXPECT_OK(syscall, address, size) \
19 do { \
20 errno = 0; \
21 rc = syscall(fd, (void*)(address), (size_t)(size)); \
22 EXPECT(rc >= 0); \
23 if (rc < 0) { \
24 warnln("Expected success: " #syscall "({:p}, {}), got rc={}, errno={}", (void*)(address), (size_t)(size), rc, errno); \
25 } \
26 } while (0)
27
28#define EXPECT_EFAULT(syscall, address, size) \
29 do { \
30 errno = 0; \
31 rc = syscall(fd, (void*)(address), (size_t)(size)); \
32 EXPECT(rc < 0); \
33 EXPECT_EQ(errno, EFAULT); \
34 if (rc >= 0 || errno != EFAULT) { \
35 warnln("Expected EFAULT: " #syscall "({:p}, {}), got rc={}, errno={}", (void*)(address), (size_t)(size), rc, errno); \
36 } \
37 } while (0)
38
39TEST_CASE(test_efault)
40{
41 int fd = open("/dev/zero", O_RDONLY);
42 int rc = -1;
43
44 // Make an inaccessible hole before the next mapping.
45 (void)mmap(nullptr, 4096, PROT_NONE, MAP_ANONYMOUS | MAP_PRIVATE, 0, 0);
46
47 // Test a one-page mapping (4KB)
48 u8* one_page = (u8*)mmap(nullptr, 4096, PROT_READ | PROT_WRITE, MAP_ANONYMOUS | MAP_PRIVATE, 0, 0);
49 VERIFY(one_page);
50 EXPECT_OK(read, one_page, 4096);
51 EXPECT_EFAULT(read, one_page, 4097);
52 EXPECT_EFAULT(read, one_page - 1, 4096);
53
54 // Make an unused hole mapping to create some inaccessible distance between our one and two-page mappings.
55 (void)mmap(nullptr, 16384, PROT_NONE, MAP_ANONYMOUS | MAP_PRIVATE, 0, 0);
56
57 // Test a two-page mapping (8KB)
58 u8* two_page = (u8*)mmap(nullptr, 8192, PROT_READ | PROT_WRITE, MAP_ANONYMOUS | MAP_PRIVATE, 0, 0);
59 VERIFY(two_page);
60
61 EXPECT_OK(read, two_page, 4096);
62 EXPECT_OK(read, two_page + 4096, 4096);
63 EXPECT_OK(read, two_page, 8192);
64 EXPECT_OK(read, two_page + 4095, 4097);
65 EXPECT_OK(read, two_page + 1, 8191);
66 EXPECT_EFAULT(read, two_page, 8193);
67 EXPECT_EFAULT(read, two_page - 1, 1);
68
69 // Check validation of pages between the first and last address.
70 ptrdiff_t distance = two_page - one_page;
71 EXPECT_EFAULT(read, one_page, (u32)distance + 1024);
72
73 constexpr auto user_range_ceiling = (sizeof(void*) == 4 ? 0xbe000000u : 0x1ffe000000);
74 u8* jerk_page = nullptr;
75
76 // Test every kernel page just because.
77 constexpr auto kernel_range_ceiling = (sizeof(void*) == 4 ? 0xffffffffu : 0x203fffffff);
78 for (u64 kernel_address = user_range_ceiling; kernel_address <= kernel_range_ceiling; kernel_address += PAGE_SIZE) {
79 jerk_page = (u8*)mmap((void*)kernel_address, PAGE_SIZE, PROT_READ | PROT_WRITE, MAP_ANONYMOUS | MAP_PRIVATE | MAP_FIXED, 0, 0);
80 EXPECT_EQ(jerk_page, MAP_FAILED);
81 EXPECT_EQ(errno, EFAULT);
82 }
83
84 // Test the page just below where the user VM ends.
85 jerk_page = (u8*)mmap((void*)(user_range_ceiling - PAGE_SIZE), PAGE_SIZE, PROT_READ | PROT_WRITE, MAP_ANONYMOUS | MAP_PRIVATE | MAP_FIXED, 0, 0);
86 EXPECT_EQ(jerk_page, (u8*)(user_range_ceiling - PAGE_SIZE));
87
88 EXPECT_OK(read, jerk_page, PAGE_SIZE);
89 EXPECT_EFAULT(read, jerk_page, PAGE_SIZE + 1);
90
91 // Test something that would wrap around the 2^32 mark.
92 EXPECT_EFAULT(read, jerk_page, 0x50000000);
93}