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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 #include <selinux/android.h>
28 
29 #include "private/android_filesystem_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 [-S context_file] [-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   struct selabel_handle* sehnd = NULL;
78   int print_capabilities = 0;
79   int opt;
80   while((opt = getopt(argc, argv, "CS:")) != -1) {
81     switch(opt) {
82     case 'C':
83       print_capabilities = 1;
84       break;
85     case 'S':
86       context_file = optarg;
87       break;
88     default:
89       usage();
90       exit(EXIT_FAILURE);
91     }
92   }
93 
94   if (context_file != NULL) {
95     sehnd = get_sehnd(context_file);
96   }
97 
98   while (fgets(buffer, 1023, stdin) != NULL) {
99     int is_dir = 0;
100     int i;
101     for (i = 0; i < 1024 && buffer[i]; ++i) {
102       switch (buffer[i]) {
103         case '\n':
104           buffer[i-is_dir] = '\0';
105           i = 1025;
106           break;
107         case '/':
108           is_dir = 1;
109           break;
110         default:
111           is_dir = 0;
112           break;
113       }
114     }
115 
116     unsigned uid = 0, gid = 0, mode = 0;
117     uint64_t capabilities;
118     fs_config(buffer, is_dir, &uid, &gid, &mode, &capabilities);
119     printf("%s %d %d %o", buffer, uid, gid, mode);
120 
121     if (sehnd != NULL) {
122       size_t buffer_strlen = strnlen(buffer, sizeof(buffer));
123       if (buffer_strlen >= sizeof(buffer)) {
124         fprintf(stderr, "non null terminated buffer, aborting\n");
125         exit(EXIT_FAILURE);
126       }
127       size_t full_name_size = buffer_strlen + 2;
128       char* full_name = (char*) malloc(full_name_size);
129       if (full_name == NULL) {
130         perror("malloc");
131         exit(EXIT_FAILURE);
132       }
133 
134       full_name[0] = '/';
135       strncpy(full_name + 1, buffer, full_name_size - 1);
136       full_name[full_name_size - 1] = '\0';
137 
138       char* secontext;
139       if (selabel_lookup(sehnd, &secontext, full_name, ( mode | (is_dir ? S_IFDIR : S_IFREG)))) {
140         secontext = strdup("u:object_r:unlabeled:s0");
141       }
142 
143       printf(" selabel=%s", secontext);
144       free(full_name);
145       freecon(secontext);
146     }
147 
148     if (print_capabilities) {
149       printf(" capabilities=0x%" PRIx64, capabilities);
150     }
151 
152     printf("\n");
153   }
154   return 0;
155 }
156