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      1 /*
      2  * Copyright (C) 2011 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 #define LOG_TAG "socket-unix"
     18 
     19 #include <stdio.h>
     20 #include <stdlib.h>
     21 #include <string.h>
     22 #include <sys/socket.h>
     23 #include <sys/uio.h>
     24 #include <sys/un.h>
     25 #include <time.h>
     26 #include <unistd.h>
     27 
     28 #include <cutils/android_get_control_file.h>
     29 #include <cutils/sockets.h>
     30 #include <log/log.h>
     31 
     32 #include "android_get_control_env.h"
     33 
     34 #ifndef TEMP_FAILURE_RETRY
     35 #define TEMP_FAILURE_RETRY(exp) (exp) // KISS implementation
     36 #endif
     37 
     38 #if defined(__ANDROID__)
     39 /* For the socket trust (credentials) check */
     40 #include <private/android_filesystem_config.h>
     41 #define __android_unused
     42 #else
     43 #define __android_unused __attribute__((__unused__))
     44 #endif
     45 
     46 bool socket_peer_is_trusted(int fd __android_unused) {
     47 #if defined(__ANDROID__)
     48     ucred cr;
     49     socklen_t len = sizeof(cr);
     50     int n = getsockopt(fd, SOL_SOCKET, SO_PEERCRED, &cr, &len);
     51 
     52     if (n != 0) {
     53         ALOGE("could not get socket credentials: %s\n", strerror(errno));
     54         return false;
     55     }
     56 
     57     if ((cr.uid != AID_ROOT) && (cr.uid != AID_SHELL)) {
     58         ALOGE("untrusted userid on other end of socket: userid %d\n", cr.uid);
     59         return false;
     60     }
     61 #endif
     62 
     63     return true;
     64 }
     65 
     66 int socket_close(int sock) {
     67     return close(sock);
     68 }
     69 
     70 int socket_set_receive_timeout(cutils_socket_t sock, int timeout_ms) {
     71     timeval tv;
     72     tv.tv_sec = timeout_ms / 1000;
     73     tv.tv_usec = (timeout_ms % 1000) * 1000;
     74     return setsockopt(sock, SOL_SOCKET, SO_RCVTIMEO, &tv, sizeof(tv));
     75 }
     76 
     77 ssize_t socket_send_buffers(cutils_socket_t sock,
     78                             const cutils_socket_buffer_t* buffers,
     79                             size_t num_buffers) {
     80     if (num_buffers > SOCKET_SEND_BUFFERS_MAX_BUFFERS) {
     81         return -1;
     82     }
     83 
     84     iovec iovec_buffers[SOCKET_SEND_BUFFERS_MAX_BUFFERS];
     85     for (size_t i = 0; i < num_buffers; ++i) {
     86         // It's safe to cast away const here; iovec declares non-const
     87         // void* because it's used for both send and receive, but since
     88         // we're only sending, the data won't be modified.
     89         iovec_buffers[i].iov_base = const_cast<void*>(buffers[i].data);
     90         iovec_buffers[i].iov_len = buffers[i].length;
     91     }
     92 
     93     return writev(sock, iovec_buffers, num_buffers);
     94 }
     95 
     96 int android_get_control_socket(const char* name) {
     97     int fd = __android_get_control_from_env(ANDROID_SOCKET_ENV_PREFIX, name);
     98 
     99     if (fd < 0) return fd;
    100 
    101     // Compare to UNIX domain socket name, must match!
    102     struct sockaddr_un addr;
    103     socklen_t addrlen = sizeof(addr);
    104     int ret = TEMP_FAILURE_RETRY(getsockname(fd, (struct sockaddr *)&addr, &addrlen));
    105     if (ret < 0) return -1;
    106     char *path = NULL;
    107     if (asprintf(&path, ANDROID_SOCKET_DIR "/%s", name) < 0) return -1;
    108     if (!path) return -1;
    109     int cmp = strcmp(addr.sun_path, path);
    110     free(path);
    111     if (cmp != 0) return -1;
    112 
    113     // It is what we think it is
    114     return fd;
    115 }
    116