1 /*
2  * Copyright (C) 2015 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 #include <stdio.h>
23 #include <stdlib.h>
24 #include <string.h>
25 #include <sys/stat.h>
26 
27 #include <selinux/label.h>
28 #include <selinux/selinux.h>
29 
30 #include "android.h"
31 #include "private/android_filesystem_config.h"
32 #include "private/canned_fs_config.h"
33 
34 #define ARRAY_SIZE(a) (sizeof(a) / sizeof((a)[0]))
35 
alloc_mounted_path(const char * mount_point,const char * subpath,char ** mounted_path)36 void alloc_mounted_path(const char *mount_point, const char *subpath, char **mounted_path) {
37     *mounted_path = malloc(strlen(mount_point) + strlen(subpath) + 1);
38     if (*mounted_path == NULL) {
39         perror("Malloc Failure.");
40         exit(EXIT_FAILURE);
41     }
42     strcpy(*mounted_path, mount_point);
43     strcat(*mounted_path, subpath);
44 }
45 
android_fs_config(fs_config_func_t fs_config_func,const char * path,struct stat * stat,const char * target_out_path,uint64_t * capabilities)46 void android_fs_config(fs_config_func_t fs_config_func, const char *path, struct stat *stat,
47         const char *target_out_path, uint64_t *capabilities) {
48     // filesystem_config does not preserve file type bits
49     mode_t stat_file_type_mask = stat->st_mode & S_IFMT;
50     if (fs_config_func)
51         fs_config_func(path, S_ISDIR(stat->st_mode), target_out_path,
52                   &stat->st_uid, &stat->st_gid, &stat->st_mode, capabilities);
53     stat->st_mode |= stat_file_type_mask;
54 }
55 
56 
get_sehnd(const char * context_file)57 struct selabel_handle *get_sehnd(const char *context_file) {
58     struct selinux_opt seopts[] = {
59         {
60             .type = SELABEL_OPT_PATH,
61             .value = context_file
62         }
63     };
64     struct selabel_handle *sehnd =
65         selabel_open(SELABEL_CTX_FILE, seopts, ARRAY_SIZE(seopts));
66 
67     if (!sehnd) {
68         perror("Error running selabel_open.");
69         exit(EXIT_FAILURE);
70     }
71     return sehnd;
72 }
73 
74 
set_selabel(const char * path,unsigned int mode,struct selabel_handle * sehnd)75 char *set_selabel(const char *path, unsigned int mode, struct selabel_handle *sehnd) {
76     char *secontext;
77     if (sehnd != NULL) {
78         int full_name_size = strlen(path) + 2;
79         char* full_name = (char*) malloc(full_name_size);
80         if (full_name == NULL) {
81             perror("Malloc Failure.");
82             exit(EXIT_FAILURE);
83         }
84 
85         full_name[0] = '/';
86         strncpy(full_name + 1, path, full_name_size - 1);
87 
88         if (selabel_lookup(sehnd, &secontext, full_name, mode)) {
89             secontext = strdup("u:object_r:unlabeled:s0");
90         }
91 
92         free(full_name);
93         return secontext;
94     }
95     perror("Selabel handle is NULL.");
96     exit(EXIT_FAILURE);
97 }
98 
set_caps(uint64_t capabilities)99 struct vfs_cap_data set_caps(uint64_t capabilities) {
100     struct vfs_cap_data cap_data;
101     memset(&cap_data, 0, sizeof(cap_data));
102 
103     if (capabilities == 0)
104         return cap_data;
105 
106     cap_data.magic_etc = VFS_CAP_REVISION | VFS_CAP_FLAGS_EFFECTIVE;
107     cap_data.data[0].permitted = (uint32_t) capabilities;
108     cap_data.data[0].inheritable = 0;
109     cap_data.data[1].permitted = (uint32_t) (capabilities >> 32);
110     cap_data.data[1].inheritable = 0;
111 
112     return cap_data;
113 }
114