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 #define TRACE_TAG TRACE_ADB
18
19 #include "sysdeps.h"
20
21 #include <errno.h>
22 #include <fcntl.h>
23 #include <mntent.h>
24 #include <stdio.h>
25 #include <stdlib.h>
26 #include <string.h>
27 #include <sys/mount.h>
28 #include <unistd.h>
29
30 #include <string>
31
32 #include "adb.h"
33 #include "adb_io.h"
34 #include "adb_utils.h"
35 #include "cutils/properties.h"
36
37 // Returns the device used to mount a directory in /proc/mounts.
find_mount(const char * dir)38 static std::string find_mount(const char* dir) {
39 std::unique_ptr<FILE, int(*)(FILE*)> fp(setmntent("/proc/mounts", "r"), endmntent);
40 if (!fp) {
41 return "";
42 }
43
44 mntent* e;
45 while ((e = getmntent(fp.get())) != nullptr) {
46 if (strcmp(dir, e->mnt_dir) == 0) {
47 return e->mnt_fsname;
48 }
49 }
50 return "";
51 }
52
make_block_device_writable(const std::string & dev)53 bool make_block_device_writable(const std::string& dev) {
54 int fd = unix_open(dev.c_str(), O_RDONLY | O_CLOEXEC);
55 if (fd == -1) {
56 return false;
57 }
58
59 int OFF = 0;
60 bool result = (ioctl(fd, BLKROSET, &OFF) != -1);
61 adb_close(fd);
62 return result;
63 }
64
remount_partition(int fd,const char * dir)65 static bool remount_partition(int fd, const char* dir) {
66 if (!directory_exists(dir)) {
67 return true;
68 }
69 std::string dev = find_mount(dir);
70 if (dev.empty()) {
71 return true;
72 }
73 if (!make_block_device_writable(dev)) {
74 WriteFdFmt(fd, "remount of %s failed; couldn't make block device %s writable: %s\n",
75 dir, dev.c_str(), strerror(errno));
76 return false;
77 }
78 if (mount(dev.c_str(), dir, "none", MS_REMOUNT, nullptr) == -1) {
79 WriteFdFmt(fd, "remount of %s failed: %s\n", dir, strerror(errno));
80 return false;
81 }
82 return true;
83 }
84
remount_service(int fd,void * cookie)85 void remount_service(int fd, void* cookie) {
86 if (getuid() != 0) {
87 WriteFdExactly(fd, "Not running as root. Try \"adb root\" first.\n");
88 adb_close(fd);
89 return;
90 }
91
92 char prop_buf[PROPERTY_VALUE_MAX];
93 property_get("partition.system.verified", prop_buf, "");
94 bool system_verified = (strlen(prop_buf) > 0);
95
96 property_get("partition.vendor.verified", prop_buf, "");
97 bool vendor_verified = (strlen(prop_buf) > 0);
98
99 if (system_verified || vendor_verified) {
100 // Allow remount but warn of likely bad effects
101 bool both = system_verified && vendor_verified;
102 WriteFdFmt(fd,
103 "dm_verity is enabled on the %s%s%s partition%s.\n",
104 system_verified ? "system" : "",
105 both ? " and " : "",
106 vendor_verified ? "vendor" : "",
107 both ? "s" : "");
108 WriteFdExactly(fd,
109 "Use \"adb disable-verity\" to disable verity.\n"
110 "If you do not, remount may succeed, however, you will still "
111 "not be able to write to these volumes.\n");
112 }
113
114 bool success = true;
115 success &= remount_partition(fd, "/system");
116 success &= remount_partition(fd, "/vendor");
117 success &= remount_partition(fd, "/oem");
118
119 WriteFdExactly(fd, success ? "remount succeeded\n" : "remount failed\n");
120
121 adb_close(fd);
122 }
123