1 /*
2 * AppArmor security module
3 *
4 * This file contains AppArmor lib definitions
5 *
6 * 2017 Canonical Ltd.
7 *
8 * This program is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU General Public License as
10 * published by the Free Software Foundation, version 2 of the
11 * License.
12 */
13
14 #ifndef __AA_LIB_H
15 #define __AA_LIB_H
16
17 #include <linux/slab.h>
18 #include <linux/fs.h>
19
20 #include "match.h"
21
22 /* Provide our own test for whether a write lock is held for asserts
23 * this is because on none SMP systems write_can_lock will always
24 * resolve to true, which is what you want for code making decisions
25 * based on it, but wrong for asserts checking that the lock is held
26 */
27 #ifdef CONFIG_SMP
28 #define write_is_locked(X) !write_can_lock(X)
29 #else
30 #define write_is_locked(X) (1)
31 #endif /* CONFIG_SMP */
32
33 /*
34 * DEBUG remains global (no per profile flag) since it is mostly used in sysctl
35 * which is not related to profile accesses.
36 */
37
38 #define DEBUG_ON (aa_g_debug)
39 #define dbg_printk(__fmt, __args...) pr_debug(__fmt, ##__args)
40 #define AA_DEBUG(fmt, args...) \
41 do { \
42 if (DEBUG_ON) \
43 pr_debug_ratelimited("AppArmor: " fmt, ##args); \
44 } while (0)
45
46 #define AA_WARN(X) WARN((X), "APPARMOR WARN %s: %s\n", __func__, #X)
47
48 #define AA_BUG(X, args...) AA_BUG_FMT((X), "" args)
49 #ifdef CONFIG_SECURITY_APPARMOR_DEBUG_ASSERTS
50 #define AA_BUG_FMT(X, fmt, args...) \
51 WARN((X), "AppArmor WARN %s: (" #X "): " fmt, __func__, ##args)
52 #else
53 #define AA_BUG_FMT(X, fmt, args...)
54 #endif
55
56 #define AA_ERROR(fmt, args...) \
57 pr_err_ratelimited("AppArmor: " fmt, ##args)
58
59 /* Flag indicating whether initialization completed */
60 extern int apparmor_initialized;
61
62 /* fn's in lib */
63 const char *skipn_spaces(const char *str, size_t n);
64 char *aa_split_fqname(char *args, char **ns_name);
65 const char *aa_splitn_fqname(const char *fqname, size_t n, const char **ns_name,
66 size_t *ns_len);
67 void aa_info_message(const char *str);
68
69 /**
70 * aa_strneq - compare null terminated @str to a non null terminated substring
71 * @str: a null terminated string
72 * @sub: a substring, not necessarily null terminated
73 * @len: length of @sub to compare
74 *
75 * The @str string must be full consumed for this to be considered a match
76 */
aa_strneq(const char * str,const char * sub,int len)77 static inline bool aa_strneq(const char *str, const char *sub, int len)
78 {
79 return !strncmp(str, sub, len) && !str[len];
80 }
81
82 /**
83 * aa_dfa_null_transition - step to next state after null character
84 * @dfa: the dfa to match against
85 * @start: the state of the dfa to start matching in
86 *
87 * aa_dfa_null_transition transitions to the next state after a null
88 * character which is not used in standard matching and is only
89 * used to separate pairs.
90 */
aa_dfa_null_transition(struct aa_dfa * dfa,unsigned int start)91 static inline unsigned int aa_dfa_null_transition(struct aa_dfa *dfa,
92 unsigned int start)
93 {
94 /* the null transition only needs the string's null terminator byte */
95 return aa_dfa_next(dfa, start, 0);
96 }
97
path_mediated_fs(struct dentry * dentry)98 static inline bool path_mediated_fs(struct dentry *dentry)
99 {
100 return !(dentry->d_sb->s_flags & MS_NOUSER);
101 }
102
103
104 struct counted_str {
105 struct kref count;
106 char name[];
107 };
108
109 #define str_to_counted(str) \
110 ((struct counted_str *)(str - offsetof(struct counted_str, name)))
111
112 #define __counted /* atm just a notation */
113
114 void aa_str_kref(struct kref *kref);
115 char *aa_str_alloc(int size, gfp_t gfp);
116
117
aa_get_str(__counted char * str)118 static inline __counted char *aa_get_str(__counted char *str)
119 {
120 if (str)
121 kref_get(&(str_to_counted(str)->count));
122
123 return str;
124 }
125
aa_put_str(__counted char * str)126 static inline void aa_put_str(__counted char *str)
127 {
128 if (str)
129 kref_put(&str_to_counted(str)->count, aa_str_kref);
130 }
131
132
133 /* struct aa_policy - common part of both namespaces and profiles
134 * @name: name of the object
135 * @hname - The hierarchical name
136 * @list: list policy object is on
137 * @profiles: head of the profiles list contained in the object
138 */
139 struct aa_policy {
140 const char *name;
141 __counted char *hname;
142 struct list_head list;
143 struct list_head profiles;
144 };
145
146 /**
147 * basename - find the last component of an hname
148 * @name: hname to find the base profile name component of (NOT NULL)
149 *
150 * Returns: the tail (base profile name) name component of an hname
151 */
basename(const char * hname)152 static inline const char *basename(const char *hname)
153 {
154 char *split;
155
156 hname = strim((char *)hname);
157 for (split = strstr(hname, "//"); split; split = strstr(hname, "//"))
158 hname = split + 2;
159
160 return hname;
161 }
162
163 /**
164 * __policy_find - find a policy by @name on a policy list
165 * @head: list to search (NOT NULL)
166 * @name: name to search for (NOT NULL)
167 *
168 * Requires: rcu_read_lock be held
169 *
170 * Returns: unrefcounted policy that match @name or NULL if not found
171 */
__policy_find(struct list_head * head,const char * name)172 static inline struct aa_policy *__policy_find(struct list_head *head,
173 const char *name)
174 {
175 struct aa_policy *policy;
176
177 list_for_each_entry_rcu(policy, head, list) {
178 if (!strcmp(policy->name, name))
179 return policy;
180 }
181 return NULL;
182 }
183
184 /**
185 * __policy_strn_find - find a policy that's name matches @len chars of @str
186 * @head: list to search (NOT NULL)
187 * @str: string to search for (NOT NULL)
188 * @len: length of match required
189 *
190 * Requires: rcu_read_lock be held
191 *
192 * Returns: unrefcounted policy that match @str or NULL if not found
193 *
194 * if @len == strlen(@strlen) then this is equiv to __policy_find
195 * other wise it allows searching for policy by a partial match of name
196 */
__policy_strn_find(struct list_head * head,const char * str,int len)197 static inline struct aa_policy *__policy_strn_find(struct list_head *head,
198 const char *str, int len)
199 {
200 struct aa_policy *policy;
201
202 list_for_each_entry_rcu(policy, head, list) {
203 if (aa_strneq(policy->name, str, len))
204 return policy;
205 }
206
207 return NULL;
208 }
209
210 bool aa_policy_init(struct aa_policy *policy, const char *prefix,
211 const char *name, gfp_t gfp);
212 void aa_policy_destroy(struct aa_policy *policy);
213
214
215 /*
216 * fn_label_build - abstract out the build of a label transition
217 * @L: label the transition is being computed for
218 * @P: profile parameter derived from L by this macro, can be passed to FN
219 * @GFP: memory allocation type to use
220 * @FN: fn to call for each profile transition. @P is set to the profile
221 *
222 * Returns: new label on success
223 * ERR_PTR if build @FN fails
224 * NULL if label_build fails due to low memory conditions
225 *
226 * @FN must return a label or ERR_PTR on failure. NULL is not allowed
227 */
228 #define fn_label_build(L, P, GFP, FN) \
229 ({ \
230 __label__ __cleanup, __done; \
231 struct aa_label *__new_; \
232 \
233 if ((L)->size > 1) { \
234 /* TODO: add cache of transitions already done */ \
235 struct label_it __i; \
236 int __j, __k, __count; \
237 DEFINE_VEC(label, __lvec); \
238 DEFINE_VEC(profile, __pvec); \
239 if (vec_setup(label, __lvec, (L)->size, (GFP))) { \
240 __new_ = NULL; \
241 goto __done; \
242 } \
243 __j = 0; \
244 label_for_each(__i, (L), (P)) { \
245 __new_ = (FN); \
246 AA_BUG(!__new_); \
247 if (IS_ERR(__new_)) \
248 goto __cleanup; \
249 __lvec[__j++] = __new_; \
250 } \
251 for (__j = __count = 0; __j < (L)->size; __j++) \
252 __count += __lvec[__j]->size; \
253 if (!vec_setup(profile, __pvec, __count, (GFP))) { \
254 for (__j = __k = 0; __j < (L)->size; __j++) { \
255 label_for_each(__i, __lvec[__j], (P)) \
256 __pvec[__k++] = aa_get_profile(P); \
257 } \
258 __count -= aa_vec_unique(__pvec, __count, 0); \
259 if (__count > 1) { \
260 __new_ = aa_vec_find_or_create_label(__pvec,\
261 __count, (GFP)); \
262 /* only fails if out of Mem */ \
263 if (!__new_) \
264 __new_ = NULL; \
265 } else \
266 __new_ = aa_get_label(&__pvec[0]->label); \
267 vec_cleanup(profile, __pvec, __count); \
268 } else \
269 __new_ = NULL; \
270 __cleanup: \
271 vec_cleanup(label, __lvec, (L)->size); \
272 } else { \
273 (P) = labels_profile(L); \
274 __new_ = (FN); \
275 } \
276 __done: \
277 if (!__new_) \
278 AA_DEBUG("label build failed\n"); \
279 (__new_); \
280 })
281
282
283 #define __fn_build_in_ns(NS, P, NS_FN, OTHER_FN) \
284 ({ \
285 struct aa_label *__new; \
286 if ((P)->ns != (NS)) \
287 __new = (OTHER_FN); \
288 else \
289 __new = (NS_FN); \
290 (__new); \
291 })
292
293 #define fn_label_build_in_ns(L, P, GFP, NS_FN, OTHER_FN) \
294 ({ \
295 fn_label_build((L), (P), (GFP), \
296 __fn_build_in_ns(labels_ns(L), (P), (NS_FN), (OTHER_FN))); \
297 })
298
299 #endif /* __AA_LIB_H */
300