1 /* SPDX-License-Identifier: GPL-2.0-only */
2 /*
3 * AppArmor security module
4 *
5 * This file contains AppArmor lib definitions
6 *
7 * 2017 Canonical Ltd.
8 */
9
10 #ifndef __AA_LIB_H
11 #define __AA_LIB_H
12
13 #include <linux/slab.h>
14 #include <linux/fs.h>
15 #include <linux/lsm_hooks.h>
16
17 #include "match.h"
18
19 /*
20 * DEBUG remains global (no per profile flag) since it is mostly used in sysctl
21 * which is not related to profile accesses.
22 */
23
24 #define DEBUG_ON (aa_g_debug)
25 #define dbg_printk(__fmt, __args...) pr_debug(__fmt, ##__args)
26 #define AA_DEBUG(fmt, args...) \
27 do { \
28 if (DEBUG_ON) \
29 pr_debug_ratelimited("AppArmor: " fmt, ##args); \
30 } while (0)
31
32 #define AA_WARN(X) WARN((X), "APPARMOR WARN %s: %s\n", __func__, #X)
33
34 #define AA_BUG(X, args...) AA_BUG_FMT((X), "" args)
35 #ifdef CONFIG_SECURITY_APPARMOR_DEBUG_ASSERTS
36 #define AA_BUG_FMT(X, fmt, args...) \
37 WARN((X), "AppArmor WARN %s: (" #X "): " fmt, __func__, ##args)
38 #else
39 #define AA_BUG_FMT(X, fmt, args...)
40 #endif
41
42 #define AA_ERROR(fmt, args...) \
43 pr_err_ratelimited("AppArmor: " fmt, ##args)
44
45 /* Flag indicating whether initialization completed */
46 extern int apparmor_initialized;
47
48 /* fn's in lib */
49 const char *skipn_spaces(const char *str, size_t n);
50 char *aa_split_fqname(char *args, char **ns_name);
51 const char *aa_splitn_fqname(const char *fqname, size_t n, const char **ns_name,
52 size_t *ns_len);
53 void aa_info_message(const char *str);
54
55 /* Security blob offsets */
56 extern struct lsm_blob_sizes apparmor_blob_sizes;
57
58 /**
59 * aa_strneq - compare null terminated @str to a non null terminated substring
60 * @str: a null terminated string
61 * @sub: a substring, not necessarily null terminated
62 * @len: length of @sub to compare
63 *
64 * The @str string must be full consumed for this to be considered a match
65 */
66 static inline bool aa_strneq(const char *str, const char *sub, int len)
67 {
68 return !strncmp(str, sub, len) && !str[len];
69 }
70
71 /**
72 * aa_dfa_null_transition - step to next state after null character
73 * @dfa: the dfa to match against
74 * @start: the state of the dfa to start matching in
75 *
76 * aa_dfa_null_transition transitions to the next state after a null
77 * character which is not used in standard matching and is only
78 * used to separate pairs.
79 */
80 static inline unsigned int aa_dfa_null_transition(struct aa_dfa *dfa,
81 unsigned int start)
82 {
83 /* the null transition only needs the string's null terminator byte */
84 return aa_dfa_next(dfa, start, 0);
85 }
86
87 static inline bool path_mediated_fs(struct dentry *dentry)
88 {
89 return !(dentry->d_sb->s_flags & SB_NOUSER);
90 }
91
92
93 struct counted_str {
94 struct kref count;
95 char name[];
96 };
97
98 #define str_to_counted(str) \
99 ((struct counted_str *)(str - offsetof(struct counted_str, name)))
100
101 #define __counted /* atm just a notation */
102
103 void aa_str_kref(struct kref *kref);
104 char *aa_str_alloc(int size, gfp_t gfp);
105
106
107 static inline __counted char *aa_get_str(__counted char *str)
108 {
109 if (str)
110 kref_get(&(str_to_counted(str)->count));
111
112 return str;
113 }
114
115 static inline void aa_put_str(__counted char *str)
116 {
117 if (str)
118 kref_put(&str_to_counted(str)->count, aa_str_kref);
119 }
120
121
122 /* struct aa_policy - common part of both namespaces and profiles
123 * @name: name of the object
124 * @hname - The hierarchical name
125 * @list: list policy object is on
126 * @profiles: head of the profiles list contained in the object
127 */
128 struct aa_policy {
129 const char *name;
130 __counted char *hname;
131 struct list_head list;
132 struct list_head profiles;
133 };
134
135 /**
136 * basename - find the last component of an hname
137 * @name: hname to find the base profile name component of (NOT NULL)
138 *
139 * Returns: the tail (base profile name) name component of an hname
140 */
141 static inline const char *basename(const char *hname)
142 {
143 char *split;
144
145 hname = strim((char *)hname);
146 for (split = strstr(hname, "//"); split; split = strstr(hname, "//"))
147 hname = split + 2;
148
149 return hname;
150 }
151
152 /**
153 * __policy_find - find a policy by @name on a policy list
154 * @head: list to search (NOT NULL)
155 * @name: name to search for (NOT NULL)
156 *
157 * Requires: rcu_read_lock be held
158 *
159 * Returns: unrefcounted policy that match @name or NULL if not found
160 */
161 static inline struct aa_policy *__policy_find(struct list_head *head,
162 const char *name)
163 {
164 struct aa_policy *policy;
165
166 list_for_each_entry_rcu(policy, head, list) {
167 if (!strcmp(policy->name, name))
168 return policy;
169 }
170 return NULL;
171 }
172
173 /**
174 * __policy_strn_find - find a policy that's name matches @len chars of @str
175 * @head: list to search (NOT NULL)
176 * @str: string to search for (NOT NULL)
177 * @len: length of match required
178 *
179 * Requires: rcu_read_lock be held
180 *
181 * Returns: unrefcounted policy that match @str or NULL if not found
182 *
183 * if @len == strlen(@strlen) then this is equiv to __policy_find
184 * other wise it allows searching for policy by a partial match of name
185 */
186 static inline struct aa_policy *__policy_strn_find(struct list_head *head,
187 const char *str, int len)
188 {
189 struct aa_policy *policy;
190
191 list_for_each_entry_rcu(policy, head, list) {
192 if (aa_strneq(policy->name, str, len))
193 return policy;
194 }
195
196 return NULL;
197 }
198
199 bool aa_policy_init(struct aa_policy *policy, const char *prefix,
200 const char *name, gfp_t gfp);
201 void aa_policy_destroy(struct aa_policy *policy);
202
203
204 /*
205 * fn_label_build - abstract out the build of a label transition
206 * @L: label the transition is being computed for
207 * @P: profile parameter derived from L by this macro, can be passed to FN
208 * @GFP: memory allocation type to use
209 * @FN: fn to call for each profile transition. @P is set to the profile
210 *
211 * Returns: new label on success
212 * ERR_PTR if build @FN fails
213 * NULL if label_build fails due to low memory conditions
214 *
215 * @FN must return a label or ERR_PTR on failure. NULL is not allowed
216 */
217 #define fn_label_build(L, P, GFP, FN) \
218 ({ \
219 __label__ __cleanup, __done; \
220 struct aa_label *__new_; \
221 \
222 if ((L)->size > 1) { \
223 /* TODO: add cache of transitions already done */ \
224 struct label_it __i; \
225 int __j, __k, __count; \
226 DEFINE_VEC(label, __lvec); \
227 DEFINE_VEC(profile, __pvec); \
228 if (vec_setup(label, __lvec, (L)->size, (GFP))) { \
229 __new_ = NULL; \
230 goto __done; \
231 } \
232 __j = 0; \
233 label_for_each(__i, (L), (P)) { \
234 __new_ = (FN); \
235 AA_BUG(!__new_); \
236 if (IS_ERR(__new_)) \
237 goto __cleanup; \
238 __lvec[__j++] = __new_; \
239 } \
240 for (__j = __count = 0; __j < (L)->size; __j++) \
241 __count += __lvec[__j]->size; \
242 if (!vec_setup(profile, __pvec, __count, (GFP))) { \
243 for (__j = __k = 0; __j < (L)->size; __j++) { \
244 label_for_each(__i, __lvec[__j], (P)) \
245 __pvec[__k++] = aa_get_profile(P); \
246 } \
247 __count -= aa_vec_unique(__pvec, __count, 0); \
248 if (__count > 1) { \
249 __new_ = aa_vec_find_or_create_label(__pvec,\
250 __count, (GFP)); \
251 /* only fails if out of Mem */ \
252 if (!__new_) \
253 __new_ = NULL; \
254 } else \
255 __new_ = aa_get_label(&__pvec[0]->label); \
256 vec_cleanup(profile, __pvec, __count); \
257 } else \
258 __new_ = NULL; \
259 __cleanup: \
260 vec_cleanup(label, __lvec, (L)->size); \
261 } else { \
262 (P) = labels_profile(L); \
263 __new_ = (FN); \
264 } \
265 __done: \
266 if (!__new_) \
267 AA_DEBUG("label build failed\n"); \
268 (__new_); \
269 })
270
271
272 #define __fn_build_in_ns(NS, P, NS_FN, OTHER_FN) \
273 ({ \
274 struct aa_label *__new; \
275 if ((P)->ns != (NS)) \
276 __new = (OTHER_FN); \
277 else \
278 __new = (NS_FN); \
279 (__new); \
280 })
281
282 #define fn_label_build_in_ns(L, P, GFP, NS_FN, OTHER_FN) \
283 ({ \
284 fn_label_build((L), (P), (GFP), \
285 __fn_build_in_ns(labels_ns(L), (P), (NS_FN), (OTHER_FN))); \
286 })
287
288 #endif /* __AA_LIB_H */