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