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