TOMOYO: Add auditing interface.
[linux-2.6.git] / security / tomoyo / mount.c
1 /*
2  * security/tomoyo/mount.c
3  *
4  * Copyright (C) 2005-2010  NTT DATA CORPORATION
5  */
6
7 #include <linux/slab.h>
8 #include "common.h"
9
10 /* String table for special mount operations. */
11 static const char * const tomoyo_mounts[TOMOYO_MAX_SPECIAL_MOUNT] = {
12         [TOMOYO_MOUNT_BIND]            = "--bind",
13         [TOMOYO_MOUNT_MOVE]            = "--move",
14         [TOMOYO_MOUNT_REMOUNT]         = "--remount",
15         [TOMOYO_MOUNT_MAKE_UNBINDABLE] = "--make-unbindable",
16         [TOMOYO_MOUNT_MAKE_PRIVATE]    = "--make-private",
17         [TOMOYO_MOUNT_MAKE_SLAVE]      = "--make-slave",
18         [TOMOYO_MOUNT_MAKE_SHARED]     = "--make-shared",
19 };
20
21 /**
22  * tomoyo_audit_mount_log - Audit mount log.
23  *
24  * @r: Pointer to "struct tomoyo_request_info".
25  *
26  * Returns 0 on success, negative value otherwise.
27  */
28 static int tomoyo_audit_mount_log(struct tomoyo_request_info *r)
29 {
30         return tomoyo_supervisor(r, "file mount %s %s %s 0x%lX\n",
31                                  r->param.mount.dev->name,
32                                  r->param.mount.dir->name,
33                                  r->param.mount.type->name,
34                                  r->param.mount.flags);
35 }
36
37 /**
38  * tomoyo_check_mount_acl - Check permission for path path path number operation.
39  *
40  * @r:   Pointer to "struct tomoyo_request_info".
41  * @ptr: Pointer to "struct tomoyo_acl_info".
42  *
43  * Returns true if granted, false otherwise.
44  */
45 static bool tomoyo_check_mount_acl(struct tomoyo_request_info *r,
46                                    const struct tomoyo_acl_info *ptr)
47 {
48         const struct tomoyo_mount_acl *acl =
49                 container_of(ptr, typeof(*acl), head);
50         return tomoyo_compare_number_union(r->param.mount.flags,
51                                            &acl->flags) &&
52                 tomoyo_compare_name_union(r->param.mount.type,
53                                           &acl->fs_type) &&
54                 tomoyo_compare_name_union(r->param.mount.dir,
55                                           &acl->dir_name) &&
56                 (!r->param.mount.need_dev ||
57                  tomoyo_compare_name_union(r->param.mount.dev,
58                                            &acl->dev_name));
59 }
60
61 /**
62  * tomoyo_mount_acl - Check permission for mount() operation.
63  *
64  * @r:        Pointer to "struct tomoyo_request_info".
65  * @dev_name: Name of device file.
66  * @dir:      Pointer to "struct path".
67  * @type:     Name of filesystem type.
68  * @flags:    Mount options.
69  *
70  * Returns 0 on success, negative value otherwise.
71  *
72  * Caller holds tomoyo_read_lock().
73  */
74 static int tomoyo_mount_acl(struct tomoyo_request_info *r, char *dev_name,
75                             struct path *dir, const char *type,
76                             unsigned long flags)
77 {
78         struct path path;
79         struct file_system_type *fstype = NULL;
80         const char *requested_type = NULL;
81         const char *requested_dir_name = NULL;
82         const char *requested_dev_name = NULL;
83         struct tomoyo_path_info rtype;
84         struct tomoyo_path_info rdev;
85         struct tomoyo_path_info rdir;
86         int need_dev = 0;
87         int error = -ENOMEM;
88
89         /* Get fstype. */
90         requested_type = tomoyo_encode(type);
91         if (!requested_type)
92                 goto out;
93         rtype.name = requested_type;
94         tomoyo_fill_path_info(&rtype);
95
96         /* Get mount point. */
97         requested_dir_name = tomoyo_realpath_from_path(dir);
98         if (!requested_dir_name) {
99                 error = -ENOMEM;
100                 goto out;
101         }
102         rdir.name = requested_dir_name;
103         tomoyo_fill_path_info(&rdir);
104
105         /* Compare fs name. */
106         if (type == tomoyo_mounts[TOMOYO_MOUNT_REMOUNT]) {
107                 /* dev_name is ignored. */
108         } else if (type == tomoyo_mounts[TOMOYO_MOUNT_MAKE_UNBINDABLE] ||
109                    type == tomoyo_mounts[TOMOYO_MOUNT_MAKE_PRIVATE] ||
110                    type == tomoyo_mounts[TOMOYO_MOUNT_MAKE_SLAVE] ||
111                    type == tomoyo_mounts[TOMOYO_MOUNT_MAKE_SHARED]) {
112                 /* dev_name is ignored. */
113         } else if (type == tomoyo_mounts[TOMOYO_MOUNT_BIND] ||
114                    type == tomoyo_mounts[TOMOYO_MOUNT_MOVE]) {
115                 need_dev = -1; /* dev_name is a directory */
116         } else {
117                 fstype = get_fs_type(type);
118                 if (!fstype) {
119                         error = -ENODEV;
120                         goto out;
121                 }
122                 if (fstype->fs_flags & FS_REQUIRES_DEV)
123                         /* dev_name is a block device file. */
124                         need_dev = 1;
125         }
126         if (need_dev) {
127                 /* Get mount point or device file. */
128                 if (kern_path(dev_name, LOOKUP_FOLLOW, &path)) {
129                         error = -ENOENT;
130                         goto out;
131                 }
132                 requested_dev_name = tomoyo_realpath_from_path(&path);
133                 path_put(&path);
134                 if (!requested_dev_name) {
135                         error = -ENOENT;
136                         goto out;
137                 }
138         } else {
139                 /* Map dev_name to "<NULL>" if no dev_name given. */
140                 if (!dev_name)
141                         dev_name = "<NULL>";
142                 requested_dev_name = tomoyo_encode(dev_name);
143                 if (!requested_dev_name) {
144                         error = -ENOMEM;
145                         goto out;
146                 }
147         }
148         rdev.name = requested_dev_name;
149         tomoyo_fill_path_info(&rdev);
150         r->param_type = TOMOYO_TYPE_MOUNT_ACL;
151         r->param.mount.need_dev = need_dev;
152         r->param.mount.dev = &rdev;
153         r->param.mount.dir = &rdir;
154         r->param.mount.type = &rtype;
155         r->param.mount.flags = flags;
156         do {
157                 tomoyo_check_acl(r, tomoyo_check_mount_acl);
158                 error = tomoyo_audit_mount_log(r);
159         } while (error == TOMOYO_RETRY_REQUEST);
160  out:
161         kfree(requested_dev_name);
162         kfree(requested_dir_name);
163         if (fstype)
164                 put_filesystem(fstype);
165         kfree(requested_type);
166         return error;
167 }
168
169 /**
170  * tomoyo_mount_permission - Check permission for mount() operation.
171  *
172  * @dev_name:  Name of device file.
173  * @path:      Pointer to "struct path".
174  * @type:      Name of filesystem type. May be NULL.
175  * @flags:     Mount options.
176  * @data_page: Optional data. May be NULL.
177  *
178  * Returns 0 on success, negative value otherwise.
179  */
180 int tomoyo_mount_permission(char *dev_name, struct path *path,
181                             const char *type, unsigned long flags,
182                             void *data_page)
183 {
184         struct tomoyo_request_info r;
185         int error;
186         int idx;
187
188         if (tomoyo_init_request_info(&r, NULL, TOMOYO_MAC_FILE_MOUNT)
189             == TOMOYO_CONFIG_DISABLED)
190                 return 0;
191         if ((flags & MS_MGC_MSK) == MS_MGC_VAL)
192                 flags &= ~MS_MGC_MSK;
193         if (flags & MS_REMOUNT) {
194                 type = tomoyo_mounts[TOMOYO_MOUNT_REMOUNT];
195                 flags &= ~MS_REMOUNT;
196         }
197         if (flags & MS_MOVE) {
198                 type = tomoyo_mounts[TOMOYO_MOUNT_MOVE];
199                 flags &= ~MS_MOVE;
200         }
201         if (flags & MS_BIND) {
202                 type = tomoyo_mounts[TOMOYO_MOUNT_BIND];
203                 flags &= ~MS_BIND;
204         }
205         if (flags & MS_UNBINDABLE) {
206                 type = tomoyo_mounts[TOMOYO_MOUNT_MAKE_UNBINDABLE];
207                 flags &= ~MS_UNBINDABLE;
208         }
209         if (flags & MS_PRIVATE) {
210                 type = tomoyo_mounts[TOMOYO_MOUNT_MAKE_PRIVATE];
211                 flags &= ~MS_PRIVATE;
212         }
213         if (flags & MS_SLAVE) {
214                 type = tomoyo_mounts[TOMOYO_MOUNT_MAKE_SLAVE];
215                 flags &= ~MS_SLAVE;
216         }
217         if (flags & MS_SHARED) {
218                 type = tomoyo_mounts[TOMOYO_MOUNT_MAKE_SHARED];
219                 flags &= ~MS_SHARED;
220         }
221         if (!type)
222                 type = "<NULL>";
223         idx = tomoyo_read_lock();
224         error = tomoyo_mount_acl(&r, dev_name, path, type, flags);
225         tomoyo_read_unlock(idx);
226         return error;
227 }