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