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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 <ctype.h>
18 #include <dirent.h>
19 #include <errno.h>
20 #include <fcntl.h>
21 #include <fts.h>
22 #include <poll.h>
23 #include <pwd.h>
24 #include <signal.h>
25 #include <stdio.h>
26 #include <stdlib.h>
27 #include <string.h>
28 #include <sys/stat.h>
29 #include <unistd.h>
30 
31 #include <fstream>
32 #include <mntent.h>
33 #include <unordered_set>
34 
35 #include <android-base/file.h>
36 #include <android-base/logging.h>
37 #include <android-base/parseint.h>
38 #include <android-base/stringprintf.h>
39 #include <android-base/strings.h>
40 
41 #include "Process.h"
42 #include "Utils.h"
43 
44 using android::base::StringPrintf;
45 
46 namespace android {
47 namespace vold {
48 
checkMaps(const std::string & path,const std::string & prefix)49 static bool checkMaps(const std::string& path, const std::string& prefix) {
50     bool found = false;
51     auto file = std::unique_ptr<FILE, decltype(&fclose)>{fopen(path.c_str(), "re"), fclose};
52     if (!file) {
53         return false;
54     }
55 
56     char* buf = nullptr;
57     size_t len = 0;
58     while (getline(&buf, &len, file.get()) != -1) {
59         std::string line(buf);
60         std::string::size_type pos = line.find('/');
61         if (pos != std::string::npos) {
62             line = line.substr(pos);
63             if (android::base::StartsWith(line, prefix)) {
64                 LOG(WARNING) << "Found map " << path << " referencing " << line;
65                 found = true;
66                 break;
67             }
68         }
69     }
70     free(buf);
71 
72     return found;
73 }
74 
checkSymlink(const std::string & path,const std::string & prefix)75 static bool checkSymlink(const std::string& path, const std::string& prefix) {
76     std::string res;
77     if (android::base::Readlink(path, &res)) {
78         if (android::base::StartsWith(res, prefix)) {
79             LOG(WARNING) << "Found symlink " << path << " referencing " << res;
80             return true;
81         }
82     }
83     return false;
84 }
85 
86 // TODO: Refactor the code with KillProcessesWithOpenFiles().
KillProcessesWithTmpfsMounts(const std::string & prefix,int signal)87 int KillProcessesWithTmpfsMounts(const std::string& prefix, int signal) {
88     std::unordered_set<pid_t> pids;
89 
90     auto proc_d = std::unique_ptr<DIR, int (*)(DIR*)>(opendir("/proc"), closedir);
91     if (!proc_d) {
92         PLOG(ERROR) << "Failed to open proc";
93         return -1;
94     }
95 
96     struct dirent* proc_de;
97     while ((proc_de = readdir(proc_d.get())) != nullptr) {
98         // We only care about valid PIDs
99         pid_t pid;
100         if (proc_de->d_type != DT_DIR) continue;
101         if (!android::base::ParseInt(proc_de->d_name, &pid)) continue;
102 
103         // Look for references to prefix
104         std::string mounts_file(StringPrintf("/proc/%d/mounts", pid));
105         auto fp = std::unique_ptr<FILE, int (*)(FILE*)>(
106                 setmntent(mounts_file.c_str(), "r"), endmntent);
107         if (!fp) {
108             PLOG(WARNING) << "Failed to open " << mounts_file;
109             continue;
110         }
111 
112         // Check if obb directory is mounted, and get all packages of mounted app data directory.
113         mntent* mentry;
114         while ((mentry = getmntent(fp.get())) != nullptr) {
115             if (mentry->mnt_fsname != nullptr && strncmp(mentry->mnt_fsname, "tmpfs", 5) == 0
116                     && android::base::StartsWith(mentry->mnt_dir, prefix)) {
117                 pids.insert(pid);
118                 break;
119             }
120         }
121     }
122     if (signal != 0) {
123         for (const auto& pid : pids) {
124             LOG(WARNING) << "Killing pid "<< pid << " with signal " << strsignal(signal) <<
125                     " because it has a mount with prefix " << prefix;
126             kill(pid, signal);
127         }
128     }
129     return pids.size();
130 }
131 
KillProcessesWithOpenFiles(const std::string & prefix,int signal,bool killFuseDaemon)132 int KillProcessesWithOpenFiles(const std::string& prefix, int signal, bool killFuseDaemon) {
133     std::unordered_set<pid_t> pids;
134 
135     auto proc_d = std::unique_ptr<DIR, int (*)(DIR*)>(opendir("/proc"), closedir);
136     if (!proc_d) {
137         PLOG(ERROR) << "Failed to open proc";
138         return -1;
139     }
140 
141     struct dirent* proc_de;
142     while ((proc_de = readdir(proc_d.get())) != nullptr) {
143         // We only care about valid PIDs
144         pid_t pid;
145         if (proc_de->d_type != DT_DIR) continue;
146         if (!android::base::ParseInt(proc_de->d_name, &pid)) continue;
147 
148         // Look for references to prefix
149         bool found = false;
150         auto path = StringPrintf("/proc/%d", pid);
151         found |= checkMaps(path + "/maps", prefix);
152         found |= checkSymlink(path + "/cwd", prefix);
153         found |= checkSymlink(path + "/root", prefix);
154         found |= checkSymlink(path + "/exe", prefix);
155 
156         auto fd_path = path + "/fd";
157         auto fd_d = std::unique_ptr<DIR, int (*)(DIR*)>(opendir(fd_path.c_str()), closedir);
158         if (!fd_d) {
159             PLOG(WARNING) << "Failed to open " << fd_path;
160         } else {
161             struct dirent* fd_de;
162             while ((fd_de = readdir(fd_d.get())) != nullptr) {
163                 if (fd_de->d_type != DT_LNK) continue;
164                 found |= checkSymlink(fd_path + "/" + fd_de->d_name, prefix);
165             }
166         }
167 
168         if (found) {
169             if (!IsFuseDaemon(pid) || killFuseDaemon) {
170                 pids.insert(pid);
171             } else {
172                 LOG(WARNING) << "Found FUSE daemon with open file. Skipping...";
173             }
174         }
175     }
176     if (signal != 0) {
177         for (const auto& pid : pids) {
178             std::string comm;
179             android::base::ReadFileToString(StringPrintf("/proc/%d/comm", pid), &comm);
180             comm = android::base::Trim(comm);
181 
182             std::string exe;
183             android::base::Readlink(StringPrintf("/proc/%d/exe", pid), &exe);
184 
185             LOG(WARNING) << "Sending " << strsignal(signal) << " to pid " << pid << " (" << comm
186                          << ", " << exe << ")";
187             kill(pid, signal);
188         }
189     }
190     return pids.size();
191 }
192 
193 }  // namespace vold
194 }  // namespace android
195