compiler/gcc4: Make quirk for asm_volatile_goto() unconditional
[sfrench/cifs-2.6.git] / security / tomoyo / mount.c
1 /*
2  * security/tomoyo/mount.c
3  *
4  * Copyright (C) 2005-2011  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. Maybe NULL.
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,
75                             const char *dev_name,
76                             struct path *dir, const char *type,
77                             unsigned long flags)
78 {
79         struct tomoyo_obj_info obj = { };
80         struct path path;
81         struct file_system_type *fstype = NULL;
82         const char *requested_type = NULL;
83         const char *requested_dir_name = NULL;
84         const char *requested_dev_name = NULL;
85         struct tomoyo_path_info rtype;
86         struct tomoyo_path_info rdev;
87         struct tomoyo_path_info rdir;
88         int need_dev = 0;
89         int error = -ENOMEM;
90         r->obj = &obj;
91
92         /* Get fstype. */
93         requested_type = tomoyo_encode(type);
94         if (!requested_type)
95                 goto out;
96         rtype.name = requested_type;
97         tomoyo_fill_path_info(&rtype);
98
99         /* Get mount point. */
100         obj.path2 = *dir;
101         requested_dir_name = tomoyo_realpath_from_path(dir);
102         if (!requested_dir_name) {
103                 error = -ENOMEM;
104                 goto out;
105         }
106         rdir.name = requested_dir_name;
107         tomoyo_fill_path_info(&rdir);
108
109         /* Compare fs name. */
110         if (type == tomoyo_mounts[TOMOYO_MOUNT_REMOUNT]) {
111                 /* dev_name is ignored. */
112         } else if (type == tomoyo_mounts[TOMOYO_MOUNT_MAKE_UNBINDABLE] ||
113                    type == tomoyo_mounts[TOMOYO_MOUNT_MAKE_PRIVATE] ||
114                    type == tomoyo_mounts[TOMOYO_MOUNT_MAKE_SLAVE] ||
115                    type == tomoyo_mounts[TOMOYO_MOUNT_MAKE_SHARED]) {
116                 /* dev_name is ignored. */
117         } else if (type == tomoyo_mounts[TOMOYO_MOUNT_BIND] ||
118                    type == tomoyo_mounts[TOMOYO_MOUNT_MOVE]) {
119                 need_dev = -1; /* dev_name is a directory */
120         } else {
121                 fstype = get_fs_type(type);
122                 if (!fstype) {
123                         error = -ENODEV;
124                         goto out;
125                 }
126                 if (fstype->fs_flags & FS_REQUIRES_DEV)
127                         /* dev_name is a block device file. */
128                         need_dev = 1;
129         }
130         if (need_dev) {
131                 /* Get mount point or device file. */
132                 if (!dev_name || kern_path(dev_name, LOOKUP_FOLLOW, &path)) {
133                         error = -ENOENT;
134                         goto out;
135                 }
136                 obj.path1 = path;
137                 requested_dev_name = tomoyo_realpath_from_path(&path);
138                 if (!requested_dev_name) {
139                         error = -ENOENT;
140                         goto out;
141                 }
142         } else {
143                 /* Map dev_name to "<NULL>" if no dev_name given. */
144                 if (!dev_name)
145                         dev_name = "<NULL>";
146                 requested_dev_name = tomoyo_encode(dev_name);
147                 if (!requested_dev_name) {
148                         error = -ENOMEM;
149                         goto out;
150                 }
151         }
152         rdev.name = requested_dev_name;
153         tomoyo_fill_path_info(&rdev);
154         r->param_type = TOMOYO_TYPE_MOUNT_ACL;
155         r->param.mount.need_dev = need_dev;
156         r->param.mount.dev = &rdev;
157         r->param.mount.dir = &rdir;
158         r->param.mount.type = &rtype;
159         r->param.mount.flags = flags;
160         do {
161                 tomoyo_check_acl(r, tomoyo_check_mount_acl);
162                 error = tomoyo_audit_mount_log(r);
163         } while (error == TOMOYO_RETRY_REQUEST);
164  out:
165         kfree(requested_dev_name);
166         kfree(requested_dir_name);
167         if (fstype)
168                 put_filesystem(fstype);
169         kfree(requested_type);
170         /* Drop refcount obtained by kern_path(). */
171         if (obj.path1.dentry)
172                 path_put(&obj.path1);
173         return error;
174 }
175
176 /**
177  * tomoyo_mount_permission - Check permission for mount() operation.
178  *
179  * @dev_name:  Name of device file. Maybe NULL.
180  * @path:      Pointer to "struct path".
181  * @type:      Name of filesystem type. Maybe NULL.
182  * @flags:     Mount options.
183  * @data_page: Optional data. Maybe NULL.
184  *
185  * Returns 0 on success, negative value otherwise.
186  */
187 int tomoyo_mount_permission(const char *dev_name, struct path *path,
188                             const char *type, unsigned long flags,
189                             void *data_page)
190 {
191         struct tomoyo_request_info r;
192         int error;
193         int idx;
194
195         if (tomoyo_init_request_info(&r, NULL, TOMOYO_MAC_FILE_MOUNT)
196             == TOMOYO_CONFIG_DISABLED)
197                 return 0;
198         if ((flags & MS_MGC_MSK) == MS_MGC_VAL)
199                 flags &= ~MS_MGC_MSK;
200         if (flags & MS_REMOUNT) {
201                 type = tomoyo_mounts[TOMOYO_MOUNT_REMOUNT];
202                 flags &= ~MS_REMOUNT;
203         } else if (flags & MS_BIND) {
204                 type = tomoyo_mounts[TOMOYO_MOUNT_BIND];
205                 flags &= ~MS_BIND;
206         } else if (flags & MS_SHARED) {
207                 if (flags & (MS_PRIVATE | MS_SLAVE | MS_UNBINDABLE))
208                         return -EINVAL;
209                 type = tomoyo_mounts[TOMOYO_MOUNT_MAKE_SHARED];
210                 flags &= ~MS_SHARED;
211         } else if (flags & MS_PRIVATE) {
212                 if (flags & (MS_SHARED | MS_SLAVE | MS_UNBINDABLE))
213                         return -EINVAL;
214                 type = tomoyo_mounts[TOMOYO_MOUNT_MAKE_PRIVATE];
215                 flags &= ~MS_PRIVATE;
216         } else if (flags & MS_SLAVE) {
217                 if (flags & (MS_SHARED | MS_PRIVATE | MS_UNBINDABLE))
218                         return -EINVAL;
219                 type = tomoyo_mounts[TOMOYO_MOUNT_MAKE_SLAVE];
220                 flags &= ~MS_SLAVE;
221         } else if (flags & MS_UNBINDABLE) {
222                 if (flags & (MS_SHARED | MS_PRIVATE | MS_SLAVE))
223                         return -EINVAL;
224                 type = tomoyo_mounts[TOMOYO_MOUNT_MAKE_UNBINDABLE];
225                 flags &= ~MS_UNBINDABLE;
226         } else if (flags & MS_MOVE) {
227                 type = tomoyo_mounts[TOMOYO_MOUNT_MOVE];
228                 flags &= ~MS_MOVE;
229         }
230         if (!type)
231                 type = "<NULL>";
232         idx = tomoyo_read_lock();
233         error = tomoyo_mount_acl(&r, dev_name, path, type, flags);
234         tomoyo_read_unlock(idx);
235         return error;
236 }