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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 <uapi/linux/mount.h>
10#include "common.h"
11
12/* String table for special mount operations. */
13static const char * const tomoyo_mounts[TOMOYO_MAX_SPECIAL_MOUNT] = {
14 [TOMOYO_MOUNT_BIND] = "--bind",
15 [TOMOYO_MOUNT_MOVE] = "--move",
16 [TOMOYO_MOUNT_REMOUNT] = "--remount",
17 [TOMOYO_MOUNT_MAKE_UNBINDABLE] = "--make-unbindable",
18 [TOMOYO_MOUNT_MAKE_PRIVATE] = "--make-private",
19 [TOMOYO_MOUNT_MAKE_SLAVE] = "--make-slave",
20 [TOMOYO_MOUNT_MAKE_SHARED] = "--make-shared",
21};
22
23/**
24 * tomoyo_audit_mount_log - Audit mount log.
25 *
26 * @r: Pointer to "struct tomoyo_request_info".
27 *
28 * Returns 0 on success, negative value otherwise.
29 */
30static int tomoyo_audit_mount_log(struct tomoyo_request_info *r)
31 __must_hold_shared(&tomoyo_ss)
32{
33 return tomoyo_supervisor(r, "file mount %s %s %s 0x%lX\n",
34 r->param.mount.dev->name,
35 r->param.mount.dir->name,
36 r->param.mount.type->name,
37 r->param.mount.flags);
38}
39
40/**
41 * tomoyo_check_mount_acl - Check permission for path path path number operation.
42 *
43 * @r: Pointer to "struct tomoyo_request_info".
44 * @ptr: Pointer to "struct tomoyo_acl_info".
45 *
46 * Returns true if granted, false otherwise.
47 */
48static bool tomoyo_check_mount_acl(struct tomoyo_request_info *r,
49 const struct tomoyo_acl_info *ptr)
50{
51 const struct tomoyo_mount_acl *acl =
52 container_of(ptr, typeof(*acl), head);
53
54 return tomoyo_compare_number_union(r->param.mount.flags,
55 &acl->flags) &&
56 tomoyo_compare_name_union(r->param.mount.type,
57 &acl->fs_type) &&
58 tomoyo_compare_name_union(r->param.mount.dir,
59 &acl->dir_name) &&
60 (!r->param.mount.need_dev ||
61 tomoyo_compare_name_union(r->param.mount.dev,
62 &acl->dev_name));
63}
64
65/**
66 * tomoyo_mount_acl - Check permission for mount() operation.
67 *
68 * @r: Pointer to "struct tomoyo_request_info".
69 * @dev_name: Name of device file. Maybe NULL.
70 * @dir: Pointer to "struct path".
71 * @type: Name of filesystem type.
72 * @flags: Mount options.
73 *
74 * Returns 0 on success, negative value otherwise.
75 *
76 * Caller holds tomoyo_read_lock().
77 */
78static int tomoyo_mount_acl(struct tomoyo_request_info *r,
79 const char *dev_name,
80 const struct path *dir, const char *type,
81 unsigned long flags)
82 __must_hold_shared(&tomoyo_ss)
83{
84 struct tomoyo_obj_info obj = { };
85 struct path path;
86 struct file_system_type *fstype = NULL;
87 const char *requested_type = NULL;
88 const char *requested_dir_name = NULL;
89 const char *requested_dev_name = NULL;
90 struct tomoyo_path_info rtype;
91 struct tomoyo_path_info rdev;
92 struct tomoyo_path_info rdir;
93 int need_dev = 0;
94 int error = -ENOMEM;
95
96 r->obj = &obj;
97
98 /* Get fstype. */
99 requested_type = tomoyo_encode(type);
100 if (!requested_type)
101 goto out;
102 rtype.name = requested_type;
103 tomoyo_fill_path_info(&rtype);
104
105 /* Get mount point. */
106 obj.path2 = *dir;
107 requested_dir_name = tomoyo_realpath_from_path(dir);
108 if (!requested_dir_name) {
109 error = -ENOMEM;
110 goto out;
111 }
112 rdir.name = requested_dir_name;
113 tomoyo_fill_path_info(&rdir);
114
115 /* Compare fs name. */
116 if (type == tomoyo_mounts[TOMOYO_MOUNT_REMOUNT]) {
117 /* dev_name is ignored. */
118 } else if (type == tomoyo_mounts[TOMOYO_MOUNT_MAKE_UNBINDABLE] ||
119 type == tomoyo_mounts[TOMOYO_MOUNT_MAKE_PRIVATE] ||
120 type == tomoyo_mounts[TOMOYO_MOUNT_MAKE_SLAVE] ||
121 type == tomoyo_mounts[TOMOYO_MOUNT_MAKE_SHARED]) {
122 /* dev_name is ignored. */
123 } else if (type == tomoyo_mounts[TOMOYO_MOUNT_BIND] ||
124 type == tomoyo_mounts[TOMOYO_MOUNT_MOVE]) {
125 need_dev = -1; /* dev_name is a directory */
126 } else {
127 fstype = get_fs_type(type);
128 if (!fstype) {
129 error = -ENODEV;
130 goto out;
131 }
132 if (fstype->fs_flags & FS_REQUIRES_DEV)
133 /* dev_name is a block device file. */
134 need_dev = 1;
135 }
136 if (need_dev) {
137 /* Get mount point or device file. */
138 if (!dev_name || kern_path(dev_name, LOOKUP_FOLLOW, &path)) {
139 error = -ENOENT;
140 goto out;
141 }
142 obj.path1 = path;
143 requested_dev_name = tomoyo_realpath_from_path(&path);
144 if (!requested_dev_name) {
145 error = -ENOENT;
146 goto out;
147 }
148 } else {
149 /* Map dev_name to "<NULL>" if no dev_name given. */
150 if (!dev_name)
151 dev_name = "<NULL>";
152 requested_dev_name = tomoyo_encode(dev_name);
153 if (!requested_dev_name) {
154 error = -ENOMEM;
155 goto out;
156 }
157 }
158 rdev.name = requested_dev_name;
159 tomoyo_fill_path_info(&rdev);
160 r->param_type = TOMOYO_TYPE_MOUNT_ACL;
161 r->param.mount.need_dev = need_dev;
162 r->param.mount.dev = &rdev;
163 r->param.mount.dir = &rdir;
164 r->param.mount.type = &rtype;
165 r->param.mount.flags = flags;
166 do {
167 tomoyo_check_acl(r, tomoyo_check_mount_acl);
168 error = tomoyo_audit_mount_log(r);
169 } while (error == TOMOYO_RETRY_REQUEST);
170 out:
171 kfree(requested_dev_name);
172 kfree(requested_dir_name);
173 if (fstype)
174 put_filesystem(fstype);
175 kfree(requested_type);
176 /* Drop refcount obtained by kern_path(). */
177 if (obj.path1.dentry)
178 path_put(&obj.path1);
179 return error;
180}
181
182/**
183 * tomoyo_mount_permission - Check permission for mount() operation.
184 *
185 * @dev_name: Name of device file. Maybe NULL.
186 * @path: Pointer to "struct path".
187 * @type: Name of filesystem type. Maybe NULL.
188 * @flags: Mount options.
189 * @data_page: Optional data. Maybe NULL.
190 *
191 * Returns 0 on success, negative value otherwise.
192 */
193int tomoyo_mount_permission(const char *dev_name, const struct path *path,
194 const char *type, unsigned long flags,
195 void *data_page)
196{
197 struct tomoyo_request_info r;
198 int error;
199 int idx;
200
201 if (tomoyo_init_request_info(&r, NULL, TOMOYO_MAC_FILE_MOUNT)
202 == TOMOYO_CONFIG_DISABLED)
203 return 0;
204 if ((flags & MS_MGC_MSK) == MS_MGC_VAL)
205 flags &= ~MS_MGC_MSK;
206 if (flags & MS_REMOUNT) {
207 type = tomoyo_mounts[TOMOYO_MOUNT_REMOUNT];
208 flags &= ~MS_REMOUNT;
209 } else if (flags & MS_BIND) {
210 type = tomoyo_mounts[TOMOYO_MOUNT_BIND];
211 flags &= ~MS_BIND;
212 } else if (flags & MS_SHARED) {
213 if (flags & (MS_PRIVATE | MS_SLAVE | MS_UNBINDABLE))
214 return -EINVAL;
215 type = tomoyo_mounts[TOMOYO_MOUNT_MAKE_SHARED];
216 flags &= ~MS_SHARED;
217 } else if (flags & MS_PRIVATE) {
218 if (flags & (MS_SHARED | MS_SLAVE | MS_UNBINDABLE))
219 return -EINVAL;
220 type = tomoyo_mounts[TOMOYO_MOUNT_MAKE_PRIVATE];
221 flags &= ~MS_PRIVATE;
222 } else if (flags & MS_SLAVE) {
223 if (flags & (MS_SHARED | MS_PRIVATE | MS_UNBINDABLE))
224 return -EINVAL;
225 type = tomoyo_mounts[TOMOYO_MOUNT_MAKE_SLAVE];
226 flags &= ~MS_SLAVE;
227 } else if (flags & MS_UNBINDABLE) {
228 if (flags & (MS_SHARED | MS_PRIVATE | MS_SLAVE))
229 return -EINVAL;
230 type = tomoyo_mounts[TOMOYO_MOUNT_MAKE_UNBINDABLE];
231 flags &= ~MS_UNBINDABLE;
232 } else if (flags & MS_MOVE) {
233 type = tomoyo_mounts[TOMOYO_MOUNT_MOVE];
234 flags &= ~MS_MOVE;
235 }
236 if (!type)
237 type = "<NULL>";
238 idx = tomoyo_read_lock();
239 error = tomoyo_mount_acl(&r, dev_name, path, type, flags);
240 tomoyo_read_unlock(idx);
241 return error;
242}