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      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 #include <stdio.h>
     18 #include <stdlib.h>
     19 #include <sys/stat.h>
     20 #include <errno.h>
     21 #include <unistd.h>
     22 #include <string.h>
     23 #include <inttypes.h>
     24 
     25 #include <selinux/selinux.h>
     26 #include <selinux/label.h>
     27 
     28 #include "private/android_filesystem_config.h"
     29 
     30 // This program takes a list of files and directories (indicated by a
     31 // trailing slash) on the stdin, and prints to stdout each input
     32 // filename along with its desired uid, gid, and mode (in octal).
     33 // The leading slash should be stripped from the input.
     34 //
     35 // After the first 4 columns, optional key=value pairs are emitted
     36 // for each file.  Currently, the following keys are supported:
     37 // * -S: selabel=[selinux_label]
     38 // * -C: capabilities=[hex capabilities value]
     39 //
     40 // Example input:
     41 //
     42 //      system/etc/dbus.conf
     43 //      data/app/
     44 //
     45 // Output:
     46 //
     47 //      system/etc/dbus.conf 1002 1002 440
     48 //      data/app 1000 1000 771
     49 //
     50 //   or if, for example, -S is used:
     51 //
     52 //      system/etc/dbus.conf 1002 1002 440 selabel=u:object_r:system_file:s0
     53 //      data/app 1000 1000 771 selabel=u:object_r:apk_data_file:s0
     54 //
     55 // Note that the output will omit the trailing slash from
     56 // directories.
     57 
     58 static struct selabel_handle* get_sehnd(const char* context_file) {
     59   struct selinux_opt seopts[] = { { SELABEL_OPT_PATH, context_file } };
     60   struct selabel_handle* sehnd = selabel_open(SELABEL_CTX_FILE, seopts, 1);
     61 
     62   if (!sehnd) {
     63     perror("error running selabel_open");
     64     exit(EXIT_FAILURE);
     65   }
     66   return sehnd;
     67 }
     68 
     69 static void usage() {
     70   fprintf(stderr, "Usage: fs_config [-D product_out_path] [-S context_file] [-C]\n");
     71 }
     72 
     73 int main(int argc, char** argv) {
     74   char buffer[1024];
     75   const char* context_file = NULL;
     76   const char* product_out_path = NULL;
     77   struct selabel_handle* sehnd = NULL;
     78   int print_capabilities = 0;
     79   int opt;
     80   while((opt = getopt(argc, argv, "CS:D:")) != -1) {
     81     switch(opt) {
     82     case 'C':
     83       print_capabilities = 1;
     84       break;
     85     case 'S':
     86       context_file = optarg;
     87       break;
     88     case 'D':
     89       product_out_path = optarg;
     90       break;
     91     default:
     92       usage();
     93       exit(EXIT_FAILURE);
     94     }
     95   }
     96 
     97   if (context_file != NULL) {
     98     sehnd = get_sehnd(context_file);
     99   }
    100 
    101   while (fgets(buffer, 1023, stdin) != NULL) {
    102     int is_dir = 0;
    103     int i;
    104     for (i = 0; i < 1024 && buffer[i]; ++i) {
    105       switch (buffer[i]) {
    106         case '\n':
    107           buffer[i-is_dir] = '\0';
    108           if (i == 0) {
    109             is_dir = 1; // empty line is considered as root directory
    110           }
    111           i = 1025;
    112           break;
    113         case '/':
    114           is_dir = 1;
    115           break;
    116         default:
    117           is_dir = 0;
    118           break;
    119       }
    120     }
    121 
    122     unsigned uid = 0, gid = 0, mode = 0;
    123     uint64_t capabilities;
    124     fs_config(buffer, is_dir, product_out_path, &uid, &gid, &mode, &capabilities);
    125     printf("%s %d %d %o", buffer, uid, gid, mode);
    126 
    127     if (sehnd != NULL) {
    128       size_t buffer_strlen = strnlen(buffer, sizeof(buffer));
    129       if (buffer_strlen >= sizeof(buffer)) {
    130         fprintf(stderr, "non null terminated buffer, aborting\n");
    131         exit(EXIT_FAILURE);
    132       }
    133       size_t full_name_size = buffer_strlen + 2;
    134       char* full_name = (char*) malloc(full_name_size);
    135       if (full_name == NULL) {
    136         perror("malloc");
    137         exit(EXIT_FAILURE);
    138       }
    139 
    140       full_name[0] = '/';
    141       strncpy(full_name + 1, buffer, full_name_size - 1);
    142       full_name[full_name_size - 1] = '\0';
    143 
    144       char* secontext;
    145       if (selabel_lookup(sehnd, &secontext, full_name, ( mode | (is_dir ? S_IFDIR : S_IFREG)))) {
    146         secontext = strdup("u:object_r:unlabeled:s0");
    147       }
    148 
    149       printf(" selabel=%s", secontext);
    150       free(full_name);
    151       freecon(secontext);
    152     }
    153 
    154     if (print_capabilities) {
    155       printf(" capabilities=0x%" PRIx64, capabilities);
    156     }
    157 
    158     printf("\n");
    159   }
    160   return 0;
    161 }
    162