1 /*
2 * Copyright (C) 2017 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 #include "safe_copy.h"
18
19 #include <errno.h>
20 #include <string.h>
21 #include <sys/user.h>
22
23 #include "android-base/logging.h"
24 #include "globals.h"
25 #include "gtest/gtest.h"
26 #include "mman.h"
27
28
29 namespace art {
30
31 #if defined(__linux__)
32
TEST(SafeCopyTest,smoke)33 TEST(SafeCopyTest, smoke) {
34 DCHECK_EQ(kPageSize, static_cast<decltype(kPageSize)>(PAGE_SIZE));
35
36 // Map four pages, mark the second one as PROT_NONE, unmap the last one.
37 void* map = mmap(nullptr, kPageSize * 4, PROT_READ | PROT_WRITE,
38 MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
39 ASSERT_NE(MAP_FAILED, map);
40 char* page1 = static_cast<char*>(map);
41 char* page2 = page1 + kPageSize;
42 char* page3 = page2 + kPageSize;
43 char* page4 = page3 + kPageSize;
44 ASSERT_EQ(0, mprotect(page1 + kPageSize, kPageSize, PROT_NONE));
45 ASSERT_EQ(0, munmap(page4, kPageSize));
46
47 page1[0] = 'a';
48 page1[kPageSize - 1] = 'z';
49
50 page3[0] = 'b';
51 page3[kPageSize - 1] = 'y';
52
53 char buf[kPageSize];
54
55 // Completely valid read.
56 memset(buf, 0xCC, sizeof(buf));
57 EXPECT_EQ(static_cast<ssize_t>(kPageSize), SafeCopy(buf, page1, kPageSize)) << strerror(errno);
58 EXPECT_EQ(0, memcmp(buf, page1, kPageSize));
59
60 // Reading into a guard page.
61 memset(buf, 0xCC, sizeof(buf));
62 EXPECT_EQ(static_cast<ssize_t>(kPageSize - 1), SafeCopy(buf, page1 + 1, kPageSize));
63 EXPECT_EQ(0, memcmp(buf, page1 + 1, kPageSize - 1));
64
65 // Reading from a guard page into a real page.
66 memset(buf, 0xCC, sizeof(buf));
67 EXPECT_EQ(0, SafeCopy(buf, page2 + kPageSize - 1, kPageSize));
68
69 // Reading off of the end of a mapping.
70 memset(buf, 0xCC, sizeof(buf));
71 EXPECT_EQ(static_cast<ssize_t>(kPageSize), SafeCopy(buf, page3, kPageSize * 2));
72 EXPECT_EQ(0, memcmp(buf, page3, kPageSize));
73
74 // Completely invalid.
75 EXPECT_EQ(0, SafeCopy(buf, page1 + kPageSize, kPageSize));
76
77 // Clean up.
78 ASSERT_EQ(0, munmap(map, kPageSize * 3));
79 }
80
TEST(SafeCopyTest,alignment)81 TEST(SafeCopyTest, alignment) {
82 DCHECK_EQ(kPageSize, static_cast<decltype(kPageSize)>(PAGE_SIZE));
83
84 // Copy the middle of a mapping to the end of another one.
85 void* src_map = mmap(nullptr, kPageSize * 3, PROT_READ | PROT_WRITE,
86 MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
87 ASSERT_NE(MAP_FAILED, src_map);
88
89 // Add a guard page to make sure we don't write past the end of the mapping.
90 void* dst_map = mmap(nullptr, kPageSize * 4, PROT_READ | PROT_WRITE,
91 MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
92 ASSERT_NE(MAP_FAILED, dst_map);
93
94 char* src = static_cast<char*>(src_map);
95 char* dst = static_cast<char*>(dst_map);
96 ASSERT_EQ(0, mprotect(dst + 3 * kPageSize, kPageSize, PROT_NONE));
97
98 src[512] = 'a';
99 src[kPageSize * 3 - 512 - 1] = 'z';
100
101 EXPECT_EQ(static_cast<ssize_t>(kPageSize * 3 - 1024),
102 SafeCopy(dst + 1024, src + 512, kPageSize * 3 - 1024));
103 EXPECT_EQ(0, memcmp(dst + 1024, src + 512, kPageSize * 3 - 1024));
104
105 ASSERT_EQ(0, munmap(src_map, kPageSize * 3));
106 ASSERT_EQ(0, munmap(dst_map, kPageSize * 4));
107 }
108
109 #endif // defined(__linux__)
110
111 } // namespace art
112