1 /* 2 * Copyright (C) 2012-2014 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 <errno.h> 18 #include <stdio.h> 19 #include <stdlib.h> 20 21 #include <private/android_filesystem_config.h> 22 23 #include "LogCommand.h" 24 25 LogCommand::LogCommand(const char *cmd) 26 : FrameworkCommand(cmd) { 27 } 28 29 // gets a list of supplementary group IDs associated with 30 // the socket peer. This is implemented by opening 31 // /proc/PID/status and look for the "Group:" line. 32 // 33 // This function introduces races especially since status 34 // can change 'shape' while reading, the net result is err 35 // on lack of permission. 36 // 37 // Race-free alternative is to introduce pairs of sockets 38 // and threads for each command and reading, one each that 39 // has open permissions, and one that has restricted 40 // permissions. 41 42 static bool groupIsLog(char *buf) { 43 char *ptr; 44 static const char ws[] = " \n"; 45 bool ret = false; 46 47 for (buf = strtok_r(buf, ws, &ptr); buf; buf = strtok_r(NULL, ws, &ptr)) { 48 errno = 0; 49 gid_t Gid = strtol(buf, NULL, 10); 50 if (errno != 0) { 51 return false; 52 } 53 if (Gid == AID_LOG) { 54 ret = true; 55 } 56 } 57 return ret; 58 } 59 60 bool clientHasLogCredentials(SocketClient * cli) { 61 uid_t uid = cli->getUid(); 62 if (uid == AID_ROOT) { 63 return true; 64 } 65 66 gid_t gid = cli->getGid(); 67 if ((gid == AID_ROOT) || (gid == AID_SYSTEM) || (gid == AID_LOG)) { 68 return true; 69 } 70 71 // FYI We will typically be here for 'adb logcat' 72 bool ret = false; 73 74 char filename[1024]; 75 snprintf(filename, sizeof(filename), "/proc/%d/status", cli->getPid()); 76 77 FILE *file = fopen(filename, "r"); 78 if (!file) { 79 return ret; 80 } 81 82 bool foundGid = false; 83 bool foundUid = false; 84 85 char line[1024]; 86 while (fgets(line, sizeof(line), file)) { 87 static const char groups_string[] = "Groups:\t"; 88 static const char uid_string[] = "Uid:\t"; 89 static const char gid_string[] = "Gid:\t"; 90 91 if (strncmp(groups_string, line, strlen(groups_string)) == 0) { 92 ret = groupIsLog(line + strlen(groups_string)); 93 if (!ret) { 94 break; 95 } 96 } else if (strncmp(uid_string, line, strlen(uid_string)) == 0) { 97 uid_t u[4] = { (uid_t) -1, (uid_t) -1, (uid_t) -1, (uid_t) -1}; 98 99 sscanf(line + strlen(uid_string), "%u\t%u\t%u\t%u", 100 &u[0], &u[1], &u[2], &u[3]); 101 102 // Protect against PID reuse by checking that the UID is the same 103 if ((uid != u[0]) || (uid != u[1]) || (uid != u[2]) || (uid != u[3])) { 104 ret = false; 105 break; 106 } 107 foundUid = true; 108 } else if (strncmp(gid_string, line, strlen(gid_string)) == 0) { 109 gid_t g[4] = { (gid_t) -1, (gid_t) -1, (gid_t) -1, (gid_t) -1}; 110 111 sscanf(line + strlen(gid_string), "%u\t%u\t%u\t%u", 112 &g[0], &g[1], &g[2], &g[3]); 113 114 // Protect against PID reuse by checking that the GID is the same 115 if ((gid != g[0]) || (gid != g[1]) || (gid != g[2]) || (gid != g[3])) { 116 ret = false; 117 break; 118 } 119 foundGid = true; 120 } 121 } 122 123 fclose(file); 124 125 if (!foundGid || !foundUid) { 126 ret = false; 127 } 128 129 return ret; 130 } 131