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 | */ |
30 | static int tomoyo_audit_mount_log(struct tomoyo_request_info *r) |
31 | { |
32 | return tomoyo_supervisor(r, fmt: "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 | */ |
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(value: r->param.mount.flags, |
54 | ptr: &acl->flags) && |
55 | tomoyo_compare_name_union(name: r->param.mount.type, |
56 | ptr: &acl->fs_type) && |
57 | tomoyo_compare_name_union(name: r->param.mount.dir, |
58 | ptr: &acl->dir_name) && |
59 | (!r->param.mount.need_dev || |
60 | tomoyo_compare_name_union(name: r->param.mount.dev, |
61 | ptr: &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 | */ |
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(str: type); |
98 | if (!requested_type) |
99 | goto out; |
100 | rtype.name = requested_type; |
101 | tomoyo_fill_path_info(ptr: &rtype); |
102 | |
103 | /* Get mount point. */ |
104 | obj.path2 = *dir; |
105 | requested_dir_name = tomoyo_realpath_from_path(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(ptr: &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(name: 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: &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(str: 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(ptr: &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, check_entry: tomoyo_check_mount_acl); |
166 | error = tomoyo_audit_mount_log(r); |
167 | } while (error == TOMOYO_RETRY_REQUEST); |
168 | out: |
169 | kfree(objp: requested_dev_name); |
170 | kfree(objp: requested_dir_name); |
171 | if (fstype) |
172 | put_filesystem(fs: fstype); |
173 | kfree(objp: 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 | */ |
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: &r, NULL, index: 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: &r, dev_name, dir: path, type, flags); |
238 | tomoyo_read_unlock(idx); |
239 | return error; |
240 | } |
241 | |