Merge branch 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel...
[linux-2.6-microblaze.git] / security / tomoyo / mount.c
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * security/tomoyo/mount.c
4  *
5  * Copyright (C) 2005-2011  NTT DATA CORPORATION
6  */
7
8 #include <linux/slab.h>
9 #include "common.h"
10
11 /* String table for special mount operations. */
12 static const char * const tomoyo_mounts[TOMOYO_MAX_SPECIAL_MOUNT] = {
13         [TOMOYO_MOUNT_BIND]            = "--bind",
14         [TOMOYO_MOUNT_MOVE]            = "--move",
15         [TOMOYO_MOUNT_REMOUNT]         = "--remount",
16         [TOMOYO_MOUNT_MAKE_UNBINDABLE] = "--make-unbindable",
17         [TOMOYO_MOUNT_MAKE_PRIVATE]    = "--make-private",
18         [TOMOYO_MOUNT_MAKE_SLAVE]      = "--make-slave",
19         [TOMOYO_MOUNT_MAKE_SHARED]     = "--make-shared",
20 };
21
22 /**
23  * tomoyo_audit_mount_log - Audit mount log.
24  *
25  * @r: Pointer to "struct tomoyo_request_info".
26  *
27  * Returns 0 on success, negative value otherwise.
28  */
29 static int tomoyo_audit_mount_log(struct tomoyo_request_info *r)
30 {
31         return tomoyo_supervisor(r, "file mount %s %s %s 0x%lX\n",
32                                  r->param.mount.dev->name,
33                                  r->param.mount.dir->name,
34                                  r->param.mount.type->name,
35                                  r->param.mount.flags);
36 }
37
38 /**
39  * tomoyo_check_mount_acl - Check permission for path path path number operation.
40  *
41  * @r:   Pointer to "struct tomoyo_request_info".
42  * @ptr: Pointer to "struct tomoyo_acl_info".
43  *
44  * Returns true if granted, false otherwise.
45  */
46 static bool tomoyo_check_mount_acl(struct tomoyo_request_info *r,
47                                    const struct tomoyo_acl_info *ptr)
48 {
49         const struct tomoyo_mount_acl *acl =
50                 container_of(ptr, typeof(*acl), head);
51         return tomoyo_compare_number_union(r->param.mount.flags,
52                                            &acl->flags) &&
53                 tomoyo_compare_name_union(r->param.mount.type,
54                                           &acl->fs_type) &&
55                 tomoyo_compare_name_union(r->param.mount.dir,
56                                           &acl->dir_name) &&
57                 (!r->param.mount.need_dev ||
58                  tomoyo_compare_name_union(r->param.mount.dev,
59                                            &acl->dev_name));
60 }
61
62 /**
63  * tomoyo_mount_acl - Check permission for mount() operation.
64  *
65  * @r:        Pointer to "struct tomoyo_request_info".
66  * @dev_name: Name of device file. Maybe NULL.
67  * @dir:      Pointer to "struct path".
68  * @type:     Name of filesystem type.
69  * @flags:    Mount options.
70  *
71  * Returns 0 on success, negative value otherwise.
72  *
73  * Caller holds tomoyo_read_lock().
74  */
75 static int tomoyo_mount_acl(struct tomoyo_request_info *r,
76                             const char *dev_name,
77                             const struct path *dir, const char *type,
78                             unsigned long flags)
79 {
80         struct tomoyo_obj_info obj = { };
81         struct path path;
82         struct file_system_type *fstype = NULL;
83         const char *requested_type = NULL;
84         const char *requested_dir_name = NULL;
85         const char *requested_dev_name = NULL;
86         struct tomoyo_path_info rtype;
87         struct tomoyo_path_info rdev;
88         struct tomoyo_path_info rdir;
89         int need_dev = 0;
90         int error = -ENOMEM;
91         r->obj = &obj;
92
93         /* Get fstype. */
94         requested_type = tomoyo_encode(type);
95         if (!requested_type)
96                 goto out;
97         rtype.name = requested_type;
98         tomoyo_fill_path_info(&rtype);
99
100         /* Get mount point. */
101         obj.path2 = *dir;
102         requested_dir_name = tomoyo_realpath_from_path(dir);
103         if (!requested_dir_name) {
104                 error = -ENOMEM;
105                 goto out;
106         }
107         rdir.name = requested_dir_name;
108         tomoyo_fill_path_info(&rdir);
109
110         /* Compare fs name. */
111         if (type == tomoyo_mounts[TOMOYO_MOUNT_REMOUNT]) {
112                 /* dev_name is ignored. */
113         } else if (type == tomoyo_mounts[TOMOYO_MOUNT_MAKE_UNBINDABLE] ||
114                    type == tomoyo_mounts[TOMOYO_MOUNT_MAKE_PRIVATE] ||
115                    type == tomoyo_mounts[TOMOYO_MOUNT_MAKE_SLAVE] ||
116                    type == tomoyo_mounts[TOMOYO_MOUNT_MAKE_SHARED]) {
117                 /* dev_name is ignored. */
118         } else if (type == tomoyo_mounts[TOMOYO_MOUNT_BIND] ||
119                    type == tomoyo_mounts[TOMOYO_MOUNT_MOVE]) {
120                 need_dev = -1; /* dev_name is a directory */
121         } else {
122                 fstype = get_fs_type(type);
123                 if (!fstype) {
124                         error = -ENODEV;
125                         goto out;
126                 }
127                 if (fstype->fs_flags & FS_REQUIRES_DEV)
128                         /* dev_name is a block device file. */
129                         need_dev = 1;
130         }
131         if (need_dev) {
132                 /* Get mount point or device file. */
133                 if (!dev_name || kern_path(dev_name, LOOKUP_FOLLOW, &path)) {
134                         error = -ENOENT;
135                         goto out;
136                 }
137                 obj.path1 = path;
138                 requested_dev_name = tomoyo_realpath_from_path(&path);
139                 if (!requested_dev_name) {
140                         error = -ENOENT;
141                         goto out;
142                 }
143         } else {
144                 /* Map dev_name to "<NULL>" if no dev_name given. */
145                 if (!dev_name)
146                         dev_name = "<NULL>";
147                 requested_dev_name = tomoyo_encode(dev_name);
148                 if (!requested_dev_name) {
149                         error = -ENOMEM;
150                         goto out;
151                 }
152         }
153         rdev.name = requested_dev_name;
154         tomoyo_fill_path_info(&rdev);
155         r->param_type = TOMOYO_TYPE_MOUNT_ACL;
156         r->param.mount.need_dev = need_dev;
157         r->param.mount.dev = &rdev;
158         r->param.mount.dir = &rdir;
159         r->param.mount.type = &rtype;
160         r->param.mount.flags = flags;
161         do {
162                 tomoyo_check_acl(r, tomoyo_check_mount_acl);
163                 error = tomoyo_audit_mount_log(r);
164         } while (error == TOMOYO_RETRY_REQUEST);
165  out:
166         kfree(requested_dev_name);
167         kfree(requested_dir_name);
168         if (fstype)
169                 put_filesystem(fstype);
170         kfree(requested_type);
171         /* Drop refcount obtained by kern_path(). */
172         if (obj.path1.dentry)
173                 path_put(&obj.path1);
174         return error;
175 }
176
177 /**
178  * tomoyo_mount_permission - Check permission for mount() operation.
179  *
180  * @dev_name:  Name of device file. Maybe NULL.
181  * @path:      Pointer to "struct path".
182  * @type:      Name of filesystem type. Maybe NULL.
183  * @flags:     Mount options.
184  * @data_page: Optional data. Maybe NULL.
185  *
186  * Returns 0 on success, negative value otherwise.
187  */
188 int tomoyo_mount_permission(const char *dev_name, const struct path *path,
189                             const char *type, unsigned long flags,
190                             void *data_page)
191 {
192         struct tomoyo_request_info r;
193         int error;
194         int idx;
195
196         if (tomoyo_init_request_info(&r, NULL, TOMOYO_MAC_FILE_MOUNT)
197             == TOMOYO_CONFIG_DISABLED)
198                 return 0;
199         if ((flags & MS_MGC_MSK) == MS_MGC_VAL)
200                 flags &= ~MS_MGC_MSK;
201         if (flags & MS_REMOUNT) {
202                 type = tomoyo_mounts[TOMOYO_MOUNT_REMOUNT];
203                 flags &= ~MS_REMOUNT;
204         } else if (flags & MS_BIND) {
205                 type = tomoyo_mounts[TOMOYO_MOUNT_BIND];
206                 flags &= ~MS_BIND;
207         } else if (flags & MS_SHARED) {
208                 if (flags & (MS_PRIVATE | MS_SLAVE | MS_UNBINDABLE))
209                         return -EINVAL;
210                 type = tomoyo_mounts[TOMOYO_MOUNT_MAKE_SHARED];
211                 flags &= ~MS_SHARED;
212         } else if (flags & MS_PRIVATE) {
213                 if (flags & (MS_SHARED | MS_SLAVE | MS_UNBINDABLE))
214                         return -EINVAL;
215                 type = tomoyo_mounts[TOMOYO_MOUNT_MAKE_PRIVATE];
216                 flags &= ~MS_PRIVATE;
217         } else if (flags & MS_SLAVE) {
218                 if (flags & (MS_SHARED | MS_PRIVATE | MS_UNBINDABLE))
219                         return -EINVAL;
220                 type = tomoyo_mounts[TOMOYO_MOUNT_MAKE_SLAVE];
221                 flags &= ~MS_SLAVE;
222         } else if (flags & MS_UNBINDABLE) {
223                 if (flags & (MS_SHARED | MS_PRIVATE | MS_SLAVE))
224                         return -EINVAL;
225                 type = tomoyo_mounts[TOMOYO_MOUNT_MAKE_UNBINDABLE];
226                 flags &= ~MS_UNBINDABLE;
227         } else if (flags & MS_MOVE) {
228                 type = tomoyo_mounts[TOMOYO_MOUNT_MOVE];
229                 flags &= ~MS_MOVE;
230         }
231         if (!type)
232                 type = "<NULL>";
233         idx = tomoyo_read_lock();
234         error = tomoyo_mount_acl(&r, dev_name, path, type, flags);
235         tomoyo_read_unlock(idx);
236         return error;
237 }