1 /*
2 * Copyright (C) 2016 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 "AshmemMapper.h"
18
19 #include <inttypes.h>
20
21 #include <log/log.h>
22 #include <sys/mman.h>
23
24 #include "AshmemMemory.h"
25
26 namespace android {
27 namespace hidl {
28 namespace memory {
29 namespace V1_0 {
30 namespace implementation {
31
32 // Methods from ::android::hidl::memory::V1_0::IMapper follow.
mapMemory(const hidl_memory & mem)33 Return<sp<IMemory>> AshmemMapper::mapMemory(const hidl_memory& mem) {
34 if (mem.handle()->numFds == 0) {
35 return nullptr;
36 }
37
38 // If ashmem service runs in 32-bit (size_t is uint32_t) and a 64-bit
39 // client process requests a memory > 2^32 bytes, the size would be
40 // converted to a 32-bit number in mmap. mmap could succeed but the
41 // mapped memory's actual size would be smaller than the reported size.
42 if (mem.size() > SIZE_MAX) {
43 ALOGE("Cannot map %" PRIu64 " bytes of memory because it is too large.", mem.size());
44 android_errorWriteLog(0x534e4554, "79376389");
45 return nullptr;
46 }
47
48 int fd = mem.handle()->data[0];
49 void* data = mmap(0, mem.size(), PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);
50 if (data == MAP_FAILED) {
51 // mmap never maps at address zero without MAP_FIXED, so we can avoid
52 // exposing clients to MAP_FAILED.
53 return nullptr;
54 }
55
56 return new AshmemMemory(mem, data);
57 }
58
59 } // namespace implementation
60 } // namespace V1_0
61 } // namespace memory
62 } // namespace hidl
63 } // namespace android
64