Process.cpp revision 586536c60b773e3517531ad8a6cb0de6722c67fc
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#include <cutils/log.h> 32 33#include "Process.h" 34 35int Process::readSymLink(const char *path, char *link, size_t max) { 36 struct stat s; 37 int length; 38 39 if (lstat(path, &s) < 0) 40 return 0; 41 if ((s.st_mode & S_IFMT) != S_IFLNK) 42 return 0; 43 44 // we have a symlink 45 length = readlink(path, link, max- 1); 46 if (length <= 0) 47 return 0; 48 link[length] = 0; 49 return 1; 50} 51 52int Process::pathMatchesMountPoint(const char* path, const char* mountPoint) { 53 int length = strlen(mountPoint); 54 if (length > 1 && strncmp(path, mountPoint, length) == 0) { 55 // we need to do extra checking if mountPoint does not end in a '/' 56 if (mountPoint[length - 1] == '/') 57 return 1; 58 // if mountPoint does not have a trailing slash, we need to make sure 59 // there is one in the path to avoid partial matches. 60 return (path[length] == 0 || path[length] == '/'); 61 } 62 63 return 0; 64} 65 66void Process::getProcessName(int pid, char *buffer, size_t max) { 67 int fd; 68 snprintf(buffer, max, "/proc/%d/cmdline", pid); 69 fd = open(buffer, O_RDONLY); 70 if (fd < 0) { 71 strcpy(buffer, "???"); 72 } else { 73 int length = read(fd, buffer, max - 1); 74 buffer[length] = 0; 75 close(fd); 76 } 77} 78 79int Process::checkFileDescriptorSymLinks(int pid, const char *mountPoint) { 80 return checkFileDescriptorSymLinks(pid, mountPoint, NULL, 0); 81} 82 83int 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 sprintf(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 continue; 102 103 // append the file name, after truncating to parent directory 104 path[parent_length] = 0; 105 strcat(path, de->d_name); 106 107 char link[PATH_MAX]; 108 109 if (readSymLink(path, link, sizeof(link)) && pathMatchesMountPoint(link, mountPoint)) { 110 if (openFilename) { 111 memset(openFilename, 0, max); 112 strncpy(openFilename, link, max-1); 113 } 114 closedir(dir); 115 return 1; 116 } 117 } 118 119 closedir(dir); 120 return 0; 121} 122 123int Process::checkFileMaps(int pid, const char *mountPoint) { 124 return checkFileMaps(pid, mountPoint, NULL, 0); 125} 126 127int Process::checkFileMaps(int pid, const char *mountPoint, char *openFilename, size_t max) { 128 FILE *file; 129 char buffer[PATH_MAX + 100]; 130 131 sprintf(buffer, "/proc/%d/maps", pid); 132 file = fopen(buffer, "r"); 133 if (!file) 134 return 0; 135 136 while (fgets(buffer, sizeof(buffer), file)) { 137 // skip to the path 138 const char* path = strchr(buffer, '/'); 139 if (path && pathMatchesMountPoint(path, mountPoint)) { 140 if (openFilename) { 141 memset(openFilename, 0, max); 142 strncpy(openFilename, path, max-1); 143 } 144 fclose(file); 145 return 1; 146 } 147 } 148 149 fclose(file); 150 return 0; 151} 152 153int Process::checkSymLink(int pid, const char *mountPoint, const char *name) { 154 char path[PATH_MAX]; 155 char link[PATH_MAX]; 156 157 sprintf(path, "/proc/%d/%s", pid, name); 158 if (readSymLink(path, link, sizeof(link)) && pathMatchesMountPoint(link, mountPoint)) 159 return 1; 160 return 0; 161} 162 163int Process::getPid(const char *s) { 164 int result = 0; 165 while (*s) { 166 if (!isdigit(*s)) return -1; 167 result = 10 * result + (*s++ - '0'); 168 } 169 return result; 170} 171 172/* 173 * Hunt down processes that have files open at the given mount point. 174 * action = 0 to just warn, 175 * action = 1 to SIGHUP, 176 * action = 2 to SIGKILL 177 */ 178// hunt down and kill processes that have files open on the given mount point 179void Process::killProcessesWithOpenFiles(const char *path, int action) { 180 DIR* dir; 181 struct dirent* de; 182 183 if (!(dir = opendir("/proc"))) { 184 LOGE("opendir failed (%s)", strerror(errno)); 185 return; 186 } 187 188 while ((de = readdir(dir))) { 189 int killed = 0; 190 int pid = getPid(de->d_name); 191 char name[PATH_MAX]; 192 193 if (pid == -1) 194 continue; 195 getProcessName(pid, name, sizeof(name)); 196 197 char openfile[PATH_MAX]; 198 199 if (checkFileDescriptorSymLinks(pid, path, openfile, sizeof(openfile))) { 200 LOGE("Process %s (%d) has open file %s", name, pid, openfile); 201 } else if (checkFileMaps(pid, path, openfile, sizeof(openfile))) { 202 LOGE("Process %s (%d) has open filemap for %s", name, pid, openfile); 203 } else if (checkSymLink(pid, path, "cwd")) { 204 LOGE("Process %s (%d) has cwd within %s", name, pid, path); 205 } else if (checkSymLink(pid, path, "root")) { 206 LOGE("Process %s (%d) has chroot within %s", name, pid, path); 207 } else if (checkSymLink(pid, path, "exe")) { 208 LOGE("Process %s (%d) has executable path within %s", name, pid, path); 209 } else { 210 continue; 211 } 212 if (action == 1) { 213 LOGW("Sending SIGHUP to process %d", pid); 214 kill(pid, SIGTERM); 215 } else if (action == 2) { 216 LOGE("Sending SIGKILL to process %d", pid); 217 kill(pid, SIGKILL); 218 } 219 } 220 closedir(dir); 221} 222