Andrei Homescu | 7c0b79f | 2022-06-30 02:00:46 +0000 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (C) 2022 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 "OS.h" |
| 18 | |
| 19 | #include <android-base/file.h> |
Andrei Homescu | 024727b | 2022-08-24 23:54:59 +0000 | [diff] [blame] | 20 | #include <binder/RpcTransportRaw.h> |
David Brazdil | 21c887c | 2022-09-23 12:25:18 +0100 | [diff] [blame] | 21 | #include <log/log.h> |
Andrei Homescu | 7c0b79f | 2022-06-30 02:00:46 +0000 | [diff] [blame] | 22 | #include <string.h> |
| 23 | |
| 24 | using android::base::ErrnoError; |
| 25 | using android::base::Result; |
| 26 | |
Tomasz Wasilczyk | 0d9dec2 | 2023-10-06 20:28:49 +0000 | [diff] [blame^] | 27 | namespace android::binder::os { |
Andrei Homescu | 7c0b79f | 2022-06-30 02:00:46 +0000 | [diff] [blame] | 28 | |
David Brazdil | 21c887c | 2022-09-23 12:25:18 +0100 | [diff] [blame] | 29 | // Linux kernel supports up to 253 (from SCM_MAX_FD) for unix sockets. |
| 30 | constexpr size_t kMaxFdsPerMsg = 253; |
| 31 | |
Andrei Homescu | 7c0b79f | 2022-06-30 02:00:46 +0000 | [diff] [blame] | 32 | Result<void> setNonBlocking(android::base::borrowed_fd fd) { |
| 33 | int flags = TEMP_FAILURE_RETRY(fcntl(fd.get(), F_GETFL)); |
| 34 | if (flags == -1) { |
| 35 | return ErrnoError() << "Could not get flags for fd"; |
| 36 | } |
| 37 | if (int ret = TEMP_FAILURE_RETRY(fcntl(fd.get(), F_SETFL, flags | O_NONBLOCK)); ret == -1) { |
| 38 | return ErrnoError() << "Could not set non-blocking flag for fd"; |
| 39 | } |
| 40 | return {}; |
| 41 | } |
| 42 | |
| 43 | status_t getRandomBytes(uint8_t* data, size_t size) { |
| 44 | int ret = TEMP_FAILURE_RETRY(open("/dev/urandom", O_RDONLY | O_CLOEXEC | O_NOFOLLOW)); |
| 45 | if (ret == -1) { |
| 46 | return -errno; |
| 47 | } |
| 48 | |
| 49 | base::unique_fd fd(ret); |
| 50 | if (!base::ReadFully(fd, data, size)) { |
| 51 | return -errno; |
| 52 | } |
| 53 | return OK; |
| 54 | } |
| 55 | |
Andrei Homescu | 24ad36e | 2022-08-04 01:33:33 +0000 | [diff] [blame] | 56 | status_t dupFileDescriptor(int oldFd, int* newFd) { |
| 57 | int ret = fcntl(oldFd, F_DUPFD_CLOEXEC, 0); |
| 58 | if (ret < 0) { |
| 59 | return -errno; |
| 60 | } |
| 61 | |
| 62 | *newFd = ret; |
| 63 | return OK; |
| 64 | } |
| 65 | |
Andrei Homescu | 024727b | 2022-08-24 23:54:59 +0000 | [diff] [blame] | 66 | std::unique_ptr<RpcTransportCtxFactory> makeDefaultRpcTransportCtxFactory() { |
| 67 | return RpcTransportCtxFactoryRaw::make(); |
| 68 | } |
| 69 | |
David Brazdil | c3964f6 | 2022-10-24 23:06:14 +0100 | [diff] [blame] | 70 | ssize_t sendMessageOnSocket( |
David Brazdil | 21c887c | 2022-09-23 12:25:18 +0100 | [diff] [blame] | 71 | const RpcTransportFd& socket, iovec* iovs, int niovs, |
| 72 | const std::vector<std::variant<base::unique_fd, base::borrowed_fd>>* ancillaryFds) { |
| 73 | if (ancillaryFds != nullptr && !ancillaryFds->empty()) { |
| 74 | if (ancillaryFds->size() > kMaxFdsPerMsg) { |
| 75 | errno = EINVAL; |
| 76 | return -1; |
| 77 | } |
| 78 | |
| 79 | // CMSG_DATA is not necessarily aligned, so we copy the FDs into a buffer and then |
| 80 | // use memcpy. |
| 81 | int fds[kMaxFdsPerMsg]; |
| 82 | for (size_t i = 0; i < ancillaryFds->size(); i++) { |
| 83 | fds[i] = std::visit([](const auto& fd) { return fd.get(); }, ancillaryFds->at(i)); |
| 84 | } |
| 85 | const size_t fdsByteSize = sizeof(int) * ancillaryFds->size(); |
| 86 | |
| 87 | alignas(struct cmsghdr) char msgControlBuf[CMSG_SPACE(sizeof(int) * kMaxFdsPerMsg)]; |
| 88 | |
| 89 | msghdr msg{ |
| 90 | .msg_iov = iovs, |
| 91 | .msg_iovlen = static_cast<decltype(msg.msg_iovlen)>(niovs), |
| 92 | .msg_control = msgControlBuf, |
| 93 | .msg_controllen = sizeof(msgControlBuf), |
| 94 | }; |
| 95 | |
| 96 | cmsghdr* cmsg = CMSG_FIRSTHDR(&msg); |
| 97 | cmsg->cmsg_level = SOL_SOCKET; |
| 98 | cmsg->cmsg_type = SCM_RIGHTS; |
| 99 | cmsg->cmsg_len = CMSG_LEN(fdsByteSize); |
| 100 | memcpy(CMSG_DATA(cmsg), fds, fdsByteSize); |
| 101 | |
| 102 | msg.msg_controllen = CMSG_SPACE(fdsByteSize); |
| 103 | return TEMP_FAILURE_RETRY(sendmsg(socket.fd.get(), &msg, MSG_NOSIGNAL | MSG_CMSG_CLOEXEC)); |
| 104 | } |
| 105 | |
| 106 | msghdr msg{ |
| 107 | .msg_iov = iovs, |
| 108 | // posix uses int, glibc uses size_t. niovs is a |
| 109 | // non-negative int and can be cast to either. |
| 110 | .msg_iovlen = static_cast<decltype(msg.msg_iovlen)>(niovs), |
| 111 | }; |
| 112 | return TEMP_FAILURE_RETRY(sendmsg(socket.fd.get(), &msg, MSG_NOSIGNAL)); |
| 113 | } |
| 114 | |
David Brazdil | c3964f6 | 2022-10-24 23:06:14 +0100 | [diff] [blame] | 115 | ssize_t receiveMessageFromSocket( |
David Brazdil | 21c887c | 2022-09-23 12:25:18 +0100 | [diff] [blame] | 116 | const RpcTransportFd& socket, iovec* iovs, int niovs, |
| 117 | std::vector<std::variant<base::unique_fd, base::borrowed_fd>>* ancillaryFds) { |
| 118 | if (ancillaryFds != nullptr) { |
| 119 | int fdBuffer[kMaxFdsPerMsg]; |
| 120 | alignas(struct cmsghdr) char msgControlBuf[CMSG_SPACE(sizeof(fdBuffer))]; |
| 121 | |
| 122 | msghdr msg{ |
| 123 | .msg_iov = iovs, |
| 124 | .msg_iovlen = static_cast<decltype(msg.msg_iovlen)>(niovs), |
| 125 | .msg_control = msgControlBuf, |
| 126 | .msg_controllen = sizeof(msgControlBuf), |
| 127 | }; |
| 128 | ssize_t processSize = TEMP_FAILURE_RETRY(recvmsg(socket.fd.get(), &msg, MSG_NOSIGNAL)); |
| 129 | if (processSize < 0) { |
| 130 | return -1; |
| 131 | } |
| 132 | |
| 133 | for (cmsghdr* cmsg = CMSG_FIRSTHDR(&msg); cmsg != nullptr; cmsg = CMSG_NXTHDR(&msg, cmsg)) { |
| 134 | if (cmsg->cmsg_level == SOL_SOCKET && cmsg->cmsg_type == SCM_RIGHTS) { |
| 135 | // NOTE: It is tempting to reinterpret_cast, but cmsg(3) explicitly asks |
| 136 | // application devs to memcpy the data to ensure memory alignment. |
| 137 | size_t dataLen = cmsg->cmsg_len - CMSG_LEN(0); |
| 138 | LOG_ALWAYS_FATAL_IF(dataLen > sizeof(fdBuffer)); // validity check |
| 139 | memcpy(fdBuffer, CMSG_DATA(cmsg), dataLen); |
| 140 | size_t fdCount = dataLen / sizeof(int); |
| 141 | ancillaryFds->reserve(ancillaryFds->size() + fdCount); |
| 142 | for (size_t i = 0; i < fdCount; i++) { |
| 143 | ancillaryFds->emplace_back(base::unique_fd(fdBuffer[i])); |
| 144 | } |
| 145 | break; |
| 146 | } |
| 147 | } |
| 148 | |
| 149 | if (msg.msg_flags & MSG_CTRUNC) { |
| 150 | errno = EPIPE; |
| 151 | return -1; |
| 152 | } |
| 153 | return processSize; |
| 154 | } |
| 155 | msghdr msg{ |
| 156 | .msg_iov = iovs, |
| 157 | // posix uses int, glibc uses size_t. niovs is a |
| 158 | // non-negative int and can be cast to either. |
| 159 | .msg_iovlen = static_cast<decltype(msg.msg_iovlen)>(niovs), |
| 160 | }; |
| 161 | |
| 162 | return TEMP_FAILURE_RETRY(recvmsg(socket.fd.get(), &msg, MSG_NOSIGNAL)); |
| 163 | } |
| 164 | |
Tomasz Wasilczyk | 0d9dec2 | 2023-10-06 20:28:49 +0000 | [diff] [blame^] | 165 | } // namespace android::binder::os |