1/*
2 * Copyright (C) 2007 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/* This file is used to define the properties of the filesystem
18** images generated by build tools (mkbootfs and mkyaffs2image) and
19** by the device side of adb.
20*/
21
22#define LOG_TAG "fs_config"
23
24#define _GNU_SOURCE
25
26#include <errno.h>
27#include <fcntl.h>
28#include <stdbool.h>
29#include <stdint.h>
30#include <stdio.h>
31#include <stdlib.h>
32#include <string.h>
33#include <sys/stat.h>
34#include <sys/types.h>
35
36#include <log/log.h>
37#include <private/android_filesystem_config.h>
38#include <utils/Compat.h>
39
40#ifndef O_BINARY
41#define O_BINARY 0
42#endif
43
44/* The following structure is stored little endian */
45struct fs_path_config_from_file {
46    uint16_t len;
47    uint16_t mode;
48    uint16_t uid;
49    uint16_t gid;
50    uint64_t capabilities;
51    char prefix[];
52} __attribute__((__aligned__(sizeof(uint64_t))));
53
54/* My kingdom for <endian.h> */
55static inline uint16_t get2LE(const uint8_t* src)
56{
57    return src[0] | (src[1] << 8);
58}
59
60static inline uint64_t get8LE(const uint8_t* src)
61{
62    uint32_t low, high;
63
64    low = src[0] | (src[1] << 8) | (src[2] << 16) | (src[3] << 24);
65    high = src[4] | (src[5] << 8) | (src[6] << 16) | (src[7] << 24);
66    return ((uint64_t) high << 32) | (uint64_t) low;
67}
68
69#define ALIGN(x, alignment) ( ((x) + ((alignment) - 1)) & ~((alignment) - 1) )
70
71/* Rules for directories.
72** These rules are applied based on "first match", so they
73** should start with the most specific path and work their
74** way up to the root.
75*/
76
77static const struct fs_path_config android_dirs[] = {
78    { 00770, AID_SYSTEM, AID_CACHE,  0, "cache" },
79    { 00771, AID_SYSTEM, AID_SYSTEM, 0, "data/app" },
80    { 00771, AID_SYSTEM, AID_SYSTEM, 0, "data/app-private" },
81    { 00771, AID_ROOT,   AID_ROOT,   0, "data/dalvik-cache" },
82    { 00771, AID_SYSTEM, AID_SYSTEM, 0, "data/data" },
83    { 00771, AID_SHELL,  AID_SHELL,  0, "data/local/tmp" },
84    { 00771, AID_SHELL,  AID_SHELL,  0, "data/local" },
85    { 01771, AID_SYSTEM, AID_MISC,   0, "data/misc" },
86    { 00770, AID_DHCP,   AID_DHCP,   0, "data/misc/dhcp" },
87    { 00771, AID_SHARED_RELRO, AID_SHARED_RELRO, 0, "data/misc/shared_relro" },
88    { 00775, AID_MEDIA_RW, AID_MEDIA_RW, 0, "data/media" },
89    { 00775, AID_MEDIA_RW, AID_MEDIA_RW, 0, "data/media/Music" },
90    { 00771, AID_SYSTEM, AID_SYSTEM, 0, "data" },
91    { 00750, AID_ROOT,   AID_SHELL,  0, "sbin" },
92    { 00755, AID_ROOT,   AID_SHELL,  0, "system/bin" },
93    { 00755, AID_ROOT,   AID_SHELL,  0, "system/vendor" },
94    { 00755, AID_ROOT,   AID_SHELL,  0, "system/xbin" },
95    { 00755, AID_ROOT,   AID_ROOT,   0, "system/etc/ppp" },
96    { 00755, AID_ROOT,   AID_SHELL,  0, "vendor" },
97    { 00777, AID_ROOT,   AID_ROOT,   0, "sdcard" },
98    { 00755, AID_ROOT,   AID_ROOT,   0, 0 },
99};
100
101/* Rules for files.
102** These rules are applied based on "first match", so they
103** should start with the most specific path and work their
104** way up to the root. Prefixes ending in * denotes wildcard
105** and will allow partial matches.
106*/
107static const char conf_dir[] = "/system/etc/fs_config_dirs";
108static const char conf_file[] = "/system/etc/fs_config_files";
109
110static const struct fs_path_config android_files[] = {
111    { 00440, AID_ROOT,      AID_SHELL,     0, "system/etc/init.goldfish.rc" },
112    { 00550, AID_ROOT,      AID_SHELL,     0, "system/etc/init.goldfish.sh" },
113    { 00550, AID_ROOT,      AID_SHELL,     0, "system/etc/init.ril" },
114    { 00550, AID_DHCP,      AID_SHELL,     0, "system/etc/dhcpcd/dhcpcd-run-hooks" },
115    { 00555, AID_ROOT,      AID_ROOT,      0, "system/etc/ppp/*" },
116    { 00555, AID_ROOT,      AID_ROOT,      0, "system/etc/rc.*" },
117    { 00444, AID_ROOT,      AID_ROOT,      0, conf_dir + 1 },
118    { 00444, AID_ROOT,      AID_ROOT,      0, conf_file + 1 },
119    { 00644, AID_SYSTEM,    AID_SYSTEM,    0, "data/app/*" },
120    { 00644, AID_MEDIA_RW,  AID_MEDIA_RW,  0, "data/media/*" },
121    { 00644, AID_SYSTEM,    AID_SYSTEM,    0, "data/app-private/*" },
122    { 00644, AID_APP,       AID_APP,       0, "data/data/*" },
123
124    /* the following five files are INTENTIONALLY set-uid, but they
125     * are NOT included on user builds. */
126    { 04750, AID_ROOT,      AID_SHELL,     0, "system/xbin/su" },
127    { 06755, AID_ROOT,      AID_ROOT,      0, "system/xbin/librank" },
128    { 06755, AID_ROOT,      AID_ROOT,      0, "system/xbin/procrank" },
129    { 06755, AID_ROOT,      AID_ROOT,      0, "system/xbin/procmem" },
130    { 04770, AID_ROOT,      AID_RADIO,     0, "system/bin/pppd-ril" },
131
132    /* the following files have enhanced capabilities and ARE included in user builds. */
133    { 00750, AID_ROOT,      AID_SHELL,     (1ULL << CAP_SETUID) | (1ULL << CAP_SETGID), "system/bin/run-as" },
134    { 00700, AID_SYSTEM,    AID_SHELL,     (1ULL << CAP_BLOCK_SUSPEND), "system/bin/inputflinger" },
135
136    { 00750, AID_ROOT,      AID_ROOT,      0, "system/bin/uncrypt" },
137    { 00750, AID_ROOT,      AID_ROOT,      0, "system/bin/install-recovery.sh" },
138    { 00755, AID_ROOT,      AID_SHELL,     0, "system/bin/*" },
139    { 00755, AID_ROOT,      AID_ROOT,      0, "system/lib/valgrind/*" },
140    { 00755, AID_ROOT,      AID_ROOT,      0, "system/lib64/valgrind/*" },
141    { 00755, AID_ROOT,      AID_SHELL,     0, "system/xbin/*" },
142    { 00755, AID_ROOT,      AID_SHELL,     0, "system/vendor/bin/*" },
143    { 00755, AID_ROOT,      AID_SHELL,     0, "vendor/bin/*" },
144    { 00750, AID_ROOT,      AID_SHELL,     0, "sbin/*" },
145    { 00755, AID_ROOT,      AID_ROOT,      0, "bin/*" },
146    { 00750, AID_ROOT,      AID_SHELL,     0, "init*" },
147    { 00750, AID_ROOT,      AID_SHELL,     0, "sbin/fs_mgr" },
148    { 00640, AID_ROOT,      AID_SHELL,     0, "fstab.*" },
149    { 00644, AID_ROOT,      AID_ROOT,      0, 0 },
150};
151
152static int fs_config_open(int dir, const char *target_out_path)
153{
154    int fd = -1;
155
156    if (target_out_path && *target_out_path) {
157        /* target_out_path is the path to the directory holding content of system partition
158           but as we cannot guaranty it ends with '/system' we need this below skip_len logic */
159        char *name = NULL;
160        int target_out_path_len = strlen(target_out_path);
161        int skip_len = strlen("/system");
162
163        if (target_out_path[target_out_path_len] == '/') {
164            skip_len++;
165        }
166        asprintf(&name, "%s%s", target_out_path, (dir ? conf_dir : conf_file) + skip_len);
167        if (name) {
168            fd = TEMP_FAILURE_RETRY(open(name, O_RDONLY | O_BINARY));
169            free(name);
170        }
171    }
172    if (fd < 0) {
173        fd = TEMP_FAILURE_RETRY(open(dir ? conf_dir : conf_file, O_RDONLY | O_BINARY));
174    }
175    return fd;
176}
177
178static bool fs_config_cmp(bool dir, const char *prefix, size_t len,
179                                    const char *path, size_t plen)
180{
181    if (dir) {
182        if (plen < len) {
183            return false;
184        }
185    } else {
186        /* If name ends in * then allow partial matches. */
187        if (prefix[len - 1] == '*') {
188            return !strncmp(prefix, path, len - 1);
189        }
190        if (plen != len) {
191            return false;
192        }
193    }
194    return !strncmp(prefix, path, len);
195}
196
197void fs_config(const char *path, int dir, const char *target_out_path,
198               unsigned *uid, unsigned *gid, unsigned *mode, uint64_t *capabilities)
199{
200    const struct fs_path_config *pc;
201    int fd, plen;
202
203    if (path[0] == '/') {
204        path++;
205    }
206
207    plen = strlen(path);
208
209    fd = fs_config_open(dir, target_out_path);
210    if (fd >= 0) {
211        struct fs_path_config_from_file header;
212
213        while (TEMP_FAILURE_RETRY(read(fd, &header, sizeof(header))) == sizeof(header)) {
214            char *prefix;
215            uint16_t host_len = get2LE((const uint8_t *)&header.len);
216            ssize_t len, remainder = host_len - sizeof(header);
217            if (remainder <= 0) {
218                ALOGE("%s len is corrupted", dir ? conf_dir : conf_file);
219                break;
220            }
221            prefix = calloc(1, remainder);
222            if (!prefix) {
223                ALOGE("%s out of memory", dir ? conf_dir : conf_file);
224                break;
225            }
226            if (TEMP_FAILURE_RETRY(read(fd, prefix, remainder)) != remainder) {
227                free(prefix);
228                ALOGE("%s prefix is truncated", dir ? conf_dir : conf_file);
229                break;
230            }
231            len = strnlen(prefix, remainder);
232            if (len >= remainder) { /* missing a terminating null */
233                free(prefix);
234                ALOGE("%s is corrupted", dir ? conf_dir : conf_file);
235                break;
236            }
237            if (fs_config_cmp(dir, prefix, len, path, plen)) {
238                free(prefix);
239                close(fd);
240                *uid = get2LE((const uint8_t *)&(header.uid));
241                *gid = get2LE((const uint8_t *)&(header.gid));
242                *mode = (*mode & (~07777)) | get2LE((const uint8_t *)&(header.mode));
243                *capabilities = get8LE((const uint8_t *)&(header.capabilities));
244                return;
245            }
246            free(prefix);
247        }
248        close(fd);
249    }
250
251    pc = dir ? android_dirs : android_files;
252    for(; pc->prefix; pc++){
253        if (fs_config_cmp(dir, pc->prefix, strlen(pc->prefix), path, plen)) {
254            break;
255        }
256    }
257    *uid = pc->uid;
258    *gid = pc->gid;
259    *mode = (*mode & (~07777)) | pc->mode;
260    *capabilities = pc->capabilities;
261}
262
263ssize_t fs_config_generate(char *buffer, size_t length, const struct fs_path_config *pc)
264{
265    struct fs_path_config_from_file *p = (struct fs_path_config_from_file *)buffer;
266    size_t len = ALIGN(sizeof(*p) + strlen(pc->prefix) + 1, sizeof(uint64_t));
267
268    if ((length < len) || (len > UINT16_MAX)) {
269        return -ENOSPC;
270    }
271    memset(p, 0, len);
272    uint16_t host_len = len;
273    p->len = get2LE((const uint8_t *)&host_len);
274    p->mode = get2LE((const uint8_t *)&(pc->mode));
275    p->uid = get2LE((const uint8_t *)&(pc->uid));
276    p->gid = get2LE((const uint8_t *)&(pc->gid));
277    p->capabilities = get8LE((const uint8_t *)&(pc->capabilities));
278    strcpy(p->prefix, pc->prefix);
279    return len;
280}
281