1 /*
2 * Copyright (C) 2024 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 #include "host/commands/process_sandboxer/proxy_common.h"
17
18 #include <sys/socket.h>
19
20 #include <cstdlib>
21 #include <string>
22
23 #include <absl/status/status.h>
24 #include <absl/status/statusor.h>
25 #include <absl/strings/numbers.h>
26
27 namespace cuttlefish::process_sandboxer {
28
RecvFrom(int sock)29 absl::StatusOr<Message> Message::RecvFrom(int sock) {
30 msghdr empty_hdr = {};
31 int len = recvmsg(sock, &empty_hdr, MSG_PEEK | MSG_TRUNC);
32 if (len < 0) {
33 return absl::ErrnoToStatus(errno, "recvmsg with MSG_PEEK failed");
34 }
35
36 Message message;
37 message.data_ = std::string(len, '\0');
38
39 iovec msg_iovec = iovec{
40 .iov_base = reinterpret_cast<void*>(message.data_.data()),
41 .iov_len = static_cast<size_t>(len),
42 };
43
44 union {
45 char buf[CMSG_SPACE(sizeof(ucred))];
46 struct cmsghdr align;
47 } cmsg_data;
48 std::memset(cmsg_data.buf, 0, sizeof(cmsg_data.buf));
49
50 msghdr hdr = msghdr{
51 .msg_iov = &msg_iovec,
52 .msg_iovlen = 1,
53 .msg_control = cmsg_data.buf,
54 .msg_controllen = sizeof(cmsg_data.buf),
55 };
56
57 auto recvmsg_ret = recvmsg(sock, &hdr, 0);
58 if (recvmsg_ret < 0) {
59 return absl::ErrnoToStatus(errno, "recvmsg failed");
60 }
61
62 for (auto cmsg = CMSG_FIRSTHDR(&hdr); cmsg != nullptr;
63 cmsg = CMSG_NXTHDR(&hdr, cmsg)) {
64 if (cmsg->cmsg_level == SOL_SOCKET && cmsg->cmsg_type == SCM_CREDENTIALS) {
65 message.credentials_ = *(ucred*)CMSG_DATA(cmsg);
66 }
67 }
68
69 return message;
70 }
71
Data() const72 const std::string& Message::Data() const { return data_; }
73
Credentials() const74 const std::optional<ucred>& Message::Credentials() const {
75 return credentials_;
76 }
77
SendStringMsg(int sock,std::string_view msg)78 absl::StatusOr<size_t> SendStringMsg(int sock, std::string_view msg) {
79 iovec msg_iovec = iovec{
80 .iov_base = (void*)msg.data(),
81 .iov_len = msg.length(),
82 };
83
84 msghdr hdr = msghdr{
85 .msg_iov = &msg_iovec,
86 .msg_iovlen = 1,
87 };
88
89 auto ret = sendmsg(sock, &hdr, MSG_EOR | MSG_NOSIGNAL);
90 return ret >= 0 ? absl::StatusOr<size_t>(ret)
91 : absl::ErrnoToStatus(errno, "sendmsg failed");
92 }
93
94 } // namespace cuttlefish::process_sandboxer
95