fs_config.c revision 80ae3084d00acefc755bf2648d887c2026089ce2 
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
58static 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
69static void usage() {
70  fprintf(stderr, "Usage: fs_config [-S context_file] [-C]\n");
71}
72
73int main(int argc, char** argv) {
74  char buffer[1024];
75  const char* context_file = NULL;
76  struct selabel_handle* sehnd = NULL;
77  int print_capabilities = 0;
78  int opt;
79  while((opt = getopt(argc, argv, "CS:")) != -1) {
80    switch(opt) {
81    case 'C':
82      print_capabilities = 1;
83      break;
84    case 'S':
85      context_file = optarg;
86      break;
87    default:
88      usage();
89      exit(EXIT_FAILURE);
90    }
91  }
92
93  if (context_file != NULL) {
94    sehnd = get_sehnd(context_file);
95  }
96
97  while (fgets(buffer, 1023, stdin) != NULL) {
98    int is_dir = 0;
99    int i;
100    for (i = 0; i < 1024 && buffer[i]; ++i) {
101      switch (buffer[i]) {
102        case '\n':
103          buffer[i-is_dir] = '\0';
104          i = 1025;
105          break;
106        case '/':
107          is_dir = 1;
108          break;
109        default:
110          is_dir = 0;
111          break;
112      }
113    }
114
115    unsigned uid = 0, gid = 0, mode = 0;
116    uint64_t capabilities;
117    fs_config(buffer, is_dir, &uid, &gid, &mode, &capabilities);
118    printf("%s %d %d %o", buffer, uid, gid, mode);
119
120    if (sehnd != NULL) {
121      size_t buffer_strlen = strnlen(buffer, sizeof(buffer));
122      if (buffer_strlen >= sizeof(buffer)) {
123        fprintf(stderr, "non null terminated buffer, aborting\n");
124        exit(EXIT_FAILURE);
125      }
126      size_t full_name_size = buffer_strlen + 2;
127      char* full_name = (char*) malloc(full_name_size);
128      if (full_name == NULL) {
129        perror("malloc");
130        exit(EXIT_FAILURE);
131      }
132
133      full_name[0] = '/';
134      strncpy(full_name + 1, buffer, full_name_size - 1);
135      full_name[full_name_size - 1] = '\0';
136
137      char* secontext;
138      if (selabel_lookup(sehnd, &secontext, full_name, ( mode | (is_dir ? S_IFDIR : S_IFREG)))) {
139        secontext = strdup("u:object_r:unlabeled:s0");
140      }
141
142      printf(" selabel=%s", secontext);
143      free(full_name);
144      freecon(secontext);
145    }
146
147    if (print_capabilities) {
148      printf(" capabilities=0x%" PRIx64, capabilities);
149    }
150
151    printf("\n");
152  }
153  return 0;
154}
155