1 /* 2 * Copyright (C) 2008 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 <stdio.h> 18 #include <unistd.h> 19 #include <errno.h> 20 #include <string.h> 21 #include <fcntl.h> 22 #include <dirent.h> 23 #include <ctype.h> 24 #include <pwd.h> 25 #include <stdlib.h> 26 #include <poll.h> 27 #include <sys/stat.h> 28 #include <signal.h> 29 30 #define LOG_TAG "ProcessKiller" 31 32 #include <android-base/file.h> 33 #include <android-base/stringprintf.h> 34 #include <android-base/logging.h> 35 #include <cutils/log.h> 36 37 #include "Process.h" 38 39 using android::base::ReadFileToString; 40 using android::base::StringPrintf; 41 42 int Process::readSymLink(const char *path, char *link, size_t max) { 43 struct stat s; 44 int length; 45 46 if (lstat(path, &s) < 0) 47 return 0; 48 if ((s.st_mode & S_IFMT) != S_IFLNK) 49 return 0; 50 51 // we have a symlink 52 length = readlink(path, link, max- 1); 53 if (length <= 0) 54 return 0; 55 link[length] = 0; 56 return 1; 57 } 58 59 int Process::pathMatchesMountPoint(const char* path, const char* mountPoint) { 60 int length = strlen(mountPoint); 61 if (length > 1 && strncmp(path, mountPoint, length) == 0) { 62 // we need to do extra checking if mountPoint does not end in a '/' 63 if (mountPoint[length - 1] == '/') 64 return 1; 65 // if mountPoint does not have a trailing slash, we need to make sure 66 // there is one in the path to avoid partial matches. 67 return (path[length] == 0 || path[length] == '/'); 68 } 69 70 return 0; 71 } 72 73 void Process::getProcessName(int pid, std::string& out_name) { 74 if (!ReadFileToString(StringPrintf("/proc/%d/cmdline", pid), &out_name)) { 75 out_name = "???"; 76 } 77 } 78 79 int Process::checkFileDescriptorSymLinks(int pid, const char *mountPoint) { 80 return checkFileDescriptorSymLinks(pid, mountPoint, NULL, 0); 81 } 82 83 int Process::checkFileDescriptorSymLinks(int pid, const char *mountPoint, char *openFilename, size_t max) { 84 85 86 // compute path to process's directory of open files 87 char path[PATH_MAX]; 88 snprintf(path, sizeof(path), "/proc/%d/fd", pid); 89 DIR *dir = opendir(path); 90 if (!dir) 91 return 0; 92 93 // remember length of the path 94 int parent_length = strlen(path); 95 // append a trailing '/' 96 path[parent_length++] = '/'; 97 98 struct dirent* de; 99 while ((de = readdir(dir))) { 100 if (!strcmp(de->d_name, ".") || !strcmp(de->d_name, "..") 101 || strlen(de->d_name) + parent_length + 1 >= PATH_MAX) 102 continue; 103 104 // append the file name, after truncating to parent directory 105 path[parent_length] = 0; 106 strlcat(path, de->d_name, PATH_MAX); 107 108 char link[PATH_MAX]; 109 110 if (readSymLink(path, link, sizeof(link)) && pathMatchesMountPoint(link, mountPoint)) { 111 if (openFilename) { 112 memset(openFilename, 0, max); 113 strlcpy(openFilename, link, max); 114 } 115 closedir(dir); 116 return 1; 117 } 118 } 119 120 closedir(dir); 121 return 0; 122 } 123 124 int Process::checkFileMaps(int pid, const char *mountPoint) { 125 return checkFileMaps(pid, mountPoint, NULL, 0); 126 } 127 128 int Process::checkFileMaps(int pid, const char *mountPoint, char *openFilename, size_t max) { 129 FILE *file; 130 char buffer[PATH_MAX + 100]; 131 132 snprintf(buffer, sizeof(buffer), "/proc/%d/maps", pid); 133 file = fopen(buffer, "re"); 134 if (!file) 135 return 0; 136 137 while (fgets(buffer, sizeof(buffer), file)) { 138 // skip to the path 139 const char* path = strchr(buffer, '/'); 140 if (path && pathMatchesMountPoint(path, mountPoint)) { 141 if (openFilename) { 142 memset(openFilename, 0, max); 143 strlcpy(openFilename, path, max); 144 } 145 fclose(file); 146 return 1; 147 } 148 } 149 150 fclose(file); 151 return 0; 152 } 153 154 int Process::checkSymLink(int pid, const char *mountPoint, const char *name) { 155 char path[PATH_MAX]; 156 char link[PATH_MAX]; 157 158 snprintf(path, sizeof(path), "/proc/%d/%s", pid, name); 159 if (readSymLink(path, link, sizeof(link)) && pathMatchesMountPoint(link, mountPoint)) 160 return 1; 161 return 0; 162 } 163 164 int Process::getPid(const char *s) { 165 int result = 0; 166 while (*s) { 167 if (!isdigit(*s)) return -1; 168 result = 10 * result + (*s++ - '0'); 169 } 170 return result; 171 } 172 173 extern "C" void vold_killProcessesWithOpenFiles(const char *path, int signal) { 174 Process::killProcessesWithOpenFiles(path, signal); 175 } 176 177 /* 178 * Hunt down processes that have files open at the given mount point. 179 */ 180 int Process::killProcessesWithOpenFiles(const char *path, int signal) { 181 int count = 0; 182 DIR* dir; 183 struct dirent* de; 184 185 if (!(dir = opendir("/proc"))) { 186 SLOGE("opendir failed (%s)", strerror(errno)); 187 return count; 188 } 189 190 while ((de = readdir(dir))) { 191 int pid = getPid(de->d_name); 192 if (pid == -1) 193 continue; 194 195 std::string name; 196 getProcessName(pid, name); 197 198 char openfile[PATH_MAX]; 199 200 if (checkFileDescriptorSymLinks(pid, path, openfile, sizeof(openfile))) { 201 SLOGE("Process %s (%d) has open file %s", name.c_str(), pid, openfile); 202 } else if (checkFileMaps(pid, path, openfile, sizeof(openfile))) { 203 SLOGE("Process %s (%d) has open filemap for %s", name.c_str(), pid, openfile); 204 } else if (checkSymLink(pid, path, "cwd")) { 205 SLOGE("Process %s (%d) has cwd within %s", name.c_str(), pid, path); 206 } else if (checkSymLink(pid, path, "root")) { 207 SLOGE("Process %s (%d) has chroot within %s", name.c_str(), pid, path); 208 } else if (checkSymLink(pid, path, "exe")) { 209 SLOGE("Process %s (%d) has executable path within %s", name.c_str(), pid, path); 210 } else { 211 continue; 212 } 213 214 if (signal != 0) { 215 SLOGW("Sending %s to process %d", strsignal(signal), pid); 216 kill(pid, signal); 217 count++; 218 } 219 } 220 closedir(dir); 221 return count; 222 } 223
