1 /*
2 * Copyright (C) 2016 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 "dumpstate"
18
19 #include "DumpstateInternal.h"
20
21 #include <stdint.h>
22 #include <stdio.h>
23 #include <string.h>
24 #include <sys/capability.h>
25 #include <sys/prctl.h>
26 #include <sys/stat.h>
27 #include <sys/types.h>
28
29 #include <cstdint>
30 #include <string>
31 #include <vector>
32
33 #include <android-base/file.h>
34 #include <cutils/log.h>
35 #include <private/android_filesystem_config.h>
36
Nanotime()37 uint64_t Nanotime() {
38 timespec ts;
39 clock_gettime(CLOCK_MONOTONIC, &ts);
40 return static_cast<uint64_t>(ts.tv_sec * NANOS_PER_SEC + ts.tv_nsec);
41 }
42
43 // Switches to non-root user and group.
DropRootUser()44 bool DropRootUser() {
45 if (getgid() == AID_SHELL && getuid() == AID_SHELL) {
46 MYLOGD("drop_root_user(): already running as Shell\n");
47 return true;
48 }
49 /* ensure we will keep capabilities when we drop root */
50 if (prctl(PR_SET_KEEPCAPS, 1) < 0) {
51 MYLOGE("prctl(PR_SET_KEEPCAPS) failed: %s\n", strerror(errno));
52 return false;
53 }
54
55 gid_t groups[] = {AID_LOG, AID_SDCARD_R, AID_SDCARD_RW, AID_MOUNT,
56 AID_INET, AID_NET_BW_STATS, AID_READPROC, AID_BLUETOOTH};
57 if (setgroups(sizeof(groups) / sizeof(groups[0]), groups) != 0) {
58 MYLOGE("Unable to setgroups, aborting: %s\n", strerror(errno));
59 return false;
60 }
61 if (setgid(AID_SHELL) != 0) {
62 MYLOGE("Unable to setgid, aborting: %s\n", strerror(errno));
63 return false;
64 }
65 if (setuid(AID_SHELL) != 0) {
66 MYLOGE("Unable to setuid, aborting: %s\n", strerror(errno));
67 return false;
68 }
69
70 struct __user_cap_header_struct capheader;
71 struct __user_cap_data_struct capdata[2];
72 memset(&capheader, 0, sizeof(capheader));
73 memset(&capdata, 0, sizeof(capdata));
74 capheader.version = _LINUX_CAPABILITY_VERSION_3;
75 capheader.pid = 0;
76
77 capdata[CAP_TO_INDEX(CAP_SYSLOG)].permitted = CAP_TO_MASK(CAP_SYSLOG);
78 capdata[CAP_TO_INDEX(CAP_SYSLOG)].effective = CAP_TO_MASK(CAP_SYSLOG);
79 capdata[0].inheritable = 0;
80 capdata[1].inheritable = 0;
81
82 if (capset(&capheader, &capdata[0]) < 0) {
83 MYLOGE("capset failed: %s\n", strerror(errno));
84 return false;
85 }
86
87 return true;
88 }
89
DumpFileFromFdToFd(const std::string & title,const std::string & path_string,int fd,int out_fd,bool dry_run)90 int DumpFileFromFdToFd(const std::string& title, const std::string& path_string, int fd, int out_fd,
91 bool dry_run) {
92 const char* path = path_string.c_str();
93 if (!title.empty()) {
94 dprintf(out_fd, "------ %s (%s", title.c_str(), path);
95
96 struct stat st;
97 // Only show the modification time of non-device files.
98 size_t path_len = strlen(path);
99 if ((path_len < 6 || memcmp(path, "/proc/", 6)) &&
100 (path_len < 5 || memcmp(path, "/sys/", 5)) &&
101 (path_len < 3 || memcmp(path, "/d/", 3)) && !fstat(fd, &st)) {
102 char stamp[80];
103 time_t mtime = st.st_mtime;
104 strftime(stamp, sizeof(stamp), "%Y-%m-%d %H:%M:%S", localtime(&mtime));
105 dprintf(out_fd, ": %s", stamp);
106 }
107 dprintf(out_fd, ") ------\n");
108 fsync(out_fd);
109 }
110 if (dry_run) {
111 if (out_fd != STDOUT_FILENO) {
112 // There is no title, but we should still print a dry-run message
113 dprintf(out_fd, "%s: skipped on dry run\n", path);
114 } else if (!title.empty()) {
115 dprintf(out_fd, "\t(skipped on dry run)\n");
116 }
117 fsync(out_fd);
118 return 0;
119 }
120 bool newline = false;
121 fd_set read_set;
122 timeval tm;
123 while (true) {
124 FD_ZERO(&read_set);
125 FD_SET(fd, &read_set);
126 /* Timeout if no data is read for 30 seconds. */
127 tm.tv_sec = 30;
128 tm.tv_usec = 0;
129 uint64_t elapsed = Nanotime();
130 int ret = TEMP_FAILURE_RETRY(select(fd + 1, &read_set, nullptr, nullptr, &tm));
131 if (ret == -1) {
132 dprintf(out_fd, "*** %s: select failed: %s\n", path, strerror(errno));
133 newline = true;
134 break;
135 } else if (ret == 0) {
136 elapsed = Nanotime() - elapsed;
137 dprintf(out_fd, "*** %s: Timed out after %.3fs\n", path, (float)elapsed / NANOS_PER_SEC);
138 newline = true;
139 break;
140 } else {
141 char buffer[65536];
142 ssize_t bytes_read = TEMP_FAILURE_RETRY(read(fd, buffer, sizeof(buffer)));
143 if (bytes_read > 0) {
144 android::base::WriteFully(out_fd, buffer, bytes_read);
145 newline = (buffer[bytes_read - 1] == '\n');
146 } else {
147 if (bytes_read == -1) {
148 dprintf(out_fd, "*** %s: Failed to read from fd: %s", path, strerror(errno));
149 newline = true;
150 }
151 break;
152 }
153 }
154 }
155 close(fd);
156
157 if (!newline) dprintf(out_fd, "\n");
158 if (!title.empty()) dprintf(out_fd, "\n");
159 return 0;
160 }
161