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 #include "private/fs_config.h"
30 
31 // This program takes a list of files and directories (indicated by a
32 // trailing slash) on the stdin, and prints to stdout each input
33 // filename along with its desired uid, gid, and mode (in octal).
34 // The leading slash should be stripped from the input.
35 //
36 // After the first 4 columns, optional key=value pairs are emitted
37 // for each file.  Currently, the following keys are supported:
38 // * -S: selabel=[selinux_label]
39 // * -C: capabilities=[hex capabilities value]
40 //
41 // Example input:
42 //
43 //      system/etc/dbus.conf
44 //      data/app/
45 //
46 // Output:
47 //
48 //      system/etc/dbus.conf 1002 1002 440
49 //      data/app 1000 1000 771
50 //
51 //   or if, for example, -S is used:
52 //
53 //      system/etc/dbus.conf 1002 1002 440 selabel=u:object_r:system_file:s0
54 //      data/app 1000 1000 771 selabel=u:object_r:apk_data_file:s0
55 //
56 // Note that the output will omit the trailing slash from
57 // directories.
58 
get_sehnd(const char * context_file)59 static struct selabel_handle* get_sehnd(const char* context_file) {
60   struct selinux_opt seopts[] = { { SELABEL_OPT_PATH, context_file } };
61   struct selabel_handle* sehnd = selabel_open(SELABEL_CTX_FILE, seopts, 1);
62 
63   if (!sehnd) {
64     perror("error running selabel_open");
65     exit(EXIT_FAILURE);
66   }
67   return sehnd;
68 }
69 
usage()70 static void usage() {
71   fprintf(stderr, "Usage: fs_config [-D product_out_path] [-S context_file] [-R root] [-C]\n");
72 }
73 
main(int argc,char ** argv)74 int main(int argc, char** argv) {
75   char buffer[1024];
76   const char* context_file = NULL;
77   const char* product_out_path = NULL;
78   char* root_path = NULL;
79   struct selabel_handle* sehnd = NULL;
80   int print_capabilities = 0;
81   int opt;
82   while((opt = getopt(argc, argv, "CS:R:D:")) != -1) {
83     switch(opt) {
84     case 'C':
85       print_capabilities = 1;
86       break;
87     case 'S':
88       context_file = optarg;
89       break;
90     case 'R':
91       root_path = optarg;
92       break;
93     case 'D':
94       product_out_path = optarg;
95       break;
96     default:
97       usage();
98       exit(EXIT_FAILURE);
99     }
100   }
101 
102   if (context_file != NULL) {
103     sehnd = get_sehnd(context_file);
104   }
105 
106   if (root_path != NULL) {
107     size_t root_len = strlen(root_path);
108     /* Trim any trailing slashes from the root path. */
109     while (root_len && root_path[--root_len] == '/') {
110       root_path[root_len] = '\0';
111     }
112   }
113 
114   while (fgets(buffer, 1023, stdin) != NULL) {
115     int is_dir = 0;
116     int i;
117     for (i = 0; i < 1024 && buffer[i]; ++i) {
118       switch (buffer[i]) {
119         case '\n':
120           buffer[i-is_dir] = '\0';
121           if (i == 0) {
122             is_dir = 1; // empty line is considered as root directory
123           }
124           i = 1025;
125           break;
126         case '/':
127           is_dir = 1;
128           break;
129         default:
130           is_dir = 0;
131           break;
132       }
133     }
134 
135     unsigned uid = 0, gid = 0, mode = 0;
136     uint64_t capabilities;
137     fs_config(buffer, is_dir, product_out_path, &uid, &gid, &mode, &capabilities);
138     if (root_path != NULL && strcmp(buffer, root_path) == 0) {
139       /* The root of the filesystem needs to be an empty string. */
140       strcpy(buffer, "");
141     }
142     printf("%s %d %d %o", buffer, uid, gid, mode);
143 
144     if (sehnd != NULL) {
145       size_t buffer_strlen = strnlen(buffer, sizeof(buffer));
146       if (buffer_strlen >= sizeof(buffer)) {
147         fprintf(stderr, "non null terminated buffer, aborting\n");
148         exit(EXIT_FAILURE);
149       }
150       size_t full_name_size = buffer_strlen + 2;
151       char* full_name = (char*) malloc(full_name_size);
152       if (full_name == NULL) {
153         perror("malloc");
154         exit(EXIT_FAILURE);
155       }
156 
157       full_name[0] = '/';
158       strncpy(full_name + 1, buffer, full_name_size - 1);
159       full_name[full_name_size - 1] = '\0';
160 
161       char* secontext;
162       if (selabel_lookup(sehnd, &secontext, full_name, ( mode | (is_dir ? S_IFDIR : S_IFREG)))) {
163         secontext = strdup("u:object_r:unlabeled:s0");
164       }
165 
166       printf(" selabel=%s", secontext);
167       free(full_name);
168       freecon(secontext);
169     }
170 
171     if (print_capabilities) {
172       printf(" capabilities=0x%" PRIx64, capabilities);
173     }
174 
175     printf("\n");
176   }
177   return 0;
178 }
179