blob: a9041a0a966b8775bd6fe2a1f7562d421b1c2ad8 (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
|
/*
* Copyright (C) 2019 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include <android-base/logging.h>
#include <android/ashmemd/IAshmemDeviceService.h>
#include <binder/IServiceManager.h>
#include <cutils/android_filesystem_config.h>
using android::IBinder;
using android::IServiceManager;
using android::String16;
using android::ashmemd::IAshmemDeviceService;
using android::os::ParcelFileDescriptor;
namespace android {
namespace ashmemd {
static bool checkBinderAccess() {
// Isolated apps are potentially subject to seccomp policy that restricts use of access()
// (b/129483782). However, apps always have access to binder, so return true.
auto uid = getuid() % AID_USER;
if (AID_ISOLATED_START <= uid && uid <= AID_ISOLATED_END) {
return true;
}
if (access("/dev/binder", R_OK | W_OK) == 0) {
return true;
}
return false;
}
sp<IAshmemDeviceService> getAshmemService() {
// Calls to defaultServiceManager() crash the process if it doesn't have appropriate
// binder permissions. Check these permissions proactively.
if (!checkBinderAccess()) {
return nullptr;
}
sp<IServiceManager> sm = android::defaultServiceManager();
sp<IBinder> binder = sm->checkService(String16("ashmem_device_service"));
return interface_cast<IAshmemDeviceService>(binder);
}
extern "C" int openAshmemdFd() {
static sp<IAshmemDeviceService> ashmemService = getAshmemService();
if (!ashmemService) {
LOG(ERROR) << "Failed to get IAshmemDeviceService.";
return -1;
}
ParcelFileDescriptor fd;
auto status = ashmemService->open(&fd);
if (!status.isOk()) {
LOG(ERROR) << "Failed IAshmemDeviceService::open()";
return -1;
}
// unique_fd is the underlying type of ParcelFileDescriptor, i.e. fd is
// closed when it falls out of scope, so we make a dup.
return dup(fd.get());
}
} // namespace ashmemd
} // namespace android
|