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      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 
     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 
     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     unsigned int uid = 0, gid = 0, mode = 0;
     51     if (fs_config_func) {
     52         fs_config_func(path, S_ISDIR(stat->st_mode), target_out_path,
     53                   &uid, &gid, &mode, capabilities);
     54         stat->st_uid = uid;
     55         stat->st_gid = gid;
     56         stat->st_mode = mode;
     57     }
     58     stat->st_mode |= stat_file_type_mask;
     59 }
     60 
     61 
     62 struct selabel_handle *get_sehnd(const char *context_file) {
     63     struct selinux_opt seopts[] = {
     64         {
     65             .type = SELABEL_OPT_PATH,
     66             .value = context_file
     67         }
     68     };
     69     struct selabel_handle *sehnd =
     70         selabel_open(SELABEL_CTX_FILE, seopts, ARRAY_SIZE(seopts));
     71 
     72     if (!sehnd) {
     73         perror("Error running selabel_open.");
     74         exit(EXIT_FAILURE);
     75     }
     76     return sehnd;
     77 }
     78 
     79 
     80 char *set_selabel(const char *path, unsigned int mode, struct selabel_handle *sehnd) {
     81     char *secontext;
     82     if (sehnd != NULL) {
     83         int full_name_size = strlen(path) + 2;
     84         char* full_name = (char*) malloc(full_name_size);
     85         if (full_name == NULL) {
     86             perror("Malloc Failure.");
     87             exit(EXIT_FAILURE);
     88         }
     89 
     90         full_name[0] = '/';
     91         strncpy(full_name + 1, path, full_name_size - 1);
     92 
     93         if (selabel_lookup(sehnd, &secontext, full_name, mode)) {
     94             secontext = strdup("u:object_r:unlabeled:s0");
     95         }
     96 
     97         free(full_name);
     98         return secontext;
     99     }
    100     perror("Selabel handle is NULL.");
    101     exit(EXIT_FAILURE);
    102 }
    103 
    104 struct vfs_cap_data set_caps(uint64_t capabilities) {
    105     struct vfs_cap_data cap_data;
    106     memset(&cap_data, 0, sizeof(cap_data));
    107 
    108     if (capabilities == 0)
    109         return cap_data;
    110 
    111     cap_data.magic_etc = VFS_CAP_REVISION | VFS_CAP_FLAGS_EFFECTIVE;
    112     cap_data.data[0].permitted = (uint32_t) capabilities;
    113     cap_data.data[0].inheritable = 0;
    114     cap_data.data[1].permitted = (uint32_t) (capabilities >> 32);
    115     cap_data.data[1].inheritable = 0;
    116 
    117     return cap_data;
    118 }
    119