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
 19extern struct aa_dfa *stacksplitdfa;
 20
 21/*
 22 * DEBUG remains global (no per profile flag) since it is mostly used in sysctl
 23 * which is not related to profile accesses.
 24 */
 25
 26#define DEBUG_ON (aa_g_debug)
 27/*
 28 * split individual debug cases out in preparation for finer grained
 29 * debug controls in the future.
 30 */
 31#define AA_DEBUG_LABEL DEBUG_ON
 32#define dbg_printk(__fmt, __args...) pr_debug(__fmt, ##__args)
 33#define AA_DEBUG(fmt, args...)						\
 34	do {								\
 35		if (DEBUG_ON)						\
 36			pr_debug_ratelimited("AppArmor: " fmt, ##args);	\
 37	} while (0)
 38
 39#define AA_WARN(X) WARN((X), "APPARMOR WARN %s: %s\n", __func__, #X)
 40
 41#define AA_BUG(X, args...)						    \
 42	do {								    \
 43		_Pragma("GCC diagnostic ignored \"-Wformat-zero-length\""); \
 44		AA_BUG_FMT((X), "" args);				    \
 45		_Pragma("GCC diagnostic warning \"-Wformat-zero-length\""); \
 46	} while (0)
 47#ifdef CONFIG_SECURITY_APPARMOR_DEBUG_ASSERTS
 48#define AA_BUG_FMT(X, fmt, args...)					\
 49	WARN((X), "AppArmor WARN %s: (" #X "): " fmt, __func__, ##args)
 50#else
 51#define AA_BUG_FMT(X, fmt, args...) no_printk(fmt, ##args)
 52#endif
 53
 54#define AA_ERROR(fmt, args...)						\
 55	pr_err_ratelimited("AppArmor: " fmt, ##args)
 56
 57/* Flag indicating whether initialization completed */
 58extern int apparmor_initialized;
 59
 60/* fn's in lib */
 61const char *skipn_spaces(const char *str, size_t n);
 62const char *aa_splitn_fqname(const char *fqname, size_t n, const char **ns_name,
 63			     size_t *ns_len);
 64void aa_info_message(const char *str);
 65
 66/* Security blob offsets */
 67extern struct lsm_blob_sizes apparmor_blob_sizes;
 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 */
 77static 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 */
 91static inline aa_state_t aa_dfa_null_transition(struct aa_dfa *dfa,
 92						aa_state_t start)
 93{
 94	/* the null transition only needs the string's null terminator byte */
 95	return aa_dfa_next(dfa, start, 0);
 96}
 97
 98static inline bool path_mediated_fs(struct dentry *dentry)
 99{
100	return !(dentry->d_sb->s_flags & SB_NOUSER);
101}
102
103struct aa_str_table {
104	int size;
105	char **table;
106};
107
108void aa_free_str_table(struct aa_str_table *table);
109
110struct counted_str {
111	struct kref count;
112	char name[];
113};
114
115#define str_to_counted(str) \
116	((struct counted_str *)(str - offsetof(struct counted_str, name)))
117
118#define __counted	/* atm just a notation */
119
120void aa_str_kref(struct kref *kref);
121char *aa_str_alloc(int size, gfp_t gfp);
122
123
124static inline __counted char *aa_get_str(__counted char *str)
125{
126	if (str)
127		kref_get(&(str_to_counted(str)->count));
128
129	return str;
130}
131
132static inline void aa_put_str(__counted char *str)
133{
134	if (str)
135		kref_put(&str_to_counted(str)->count, aa_str_kref);
136}
137
138
139/* struct aa_policy - common part of both namespaces and profiles
140 * @name: name of the object
141 * @hname - The hierarchical name
142 * @list: list policy object is on
143 * @profiles: head of the profiles list contained in the object
144 */
145struct aa_policy {
146	const char *name;
147	__counted char *hname;
148	struct list_head list;
149	struct list_head profiles;
150};
151
152/**
153 * basename - find the last component of an hname
154 * @name: hname to find the base profile name component of  (NOT NULL)
155 *
156 * Returns: the tail (base profile name) name component of an hname
157 */
158static inline const char *basename(const char *hname)
159{
160	char *split;
161
162	hname = strim((char *)hname);
163	for (split = strstr(hname, "//"); split; split = strstr(hname, "//"))
164		hname = split + 2;
165
166	return hname;
167}
168
169/**
170 * __policy_find - find a policy by @name on a policy list
171 * @head: list to search  (NOT NULL)
172 * @name: name to search for  (NOT NULL)
173 *
174 * Requires: rcu_read_lock be held
175 *
176 * Returns: unrefcounted policy that match @name or NULL if not found
177 */
178static inline struct aa_policy *__policy_find(struct list_head *head,
179					      const char *name)
180{
181	struct aa_policy *policy;
182
183	list_for_each_entry_rcu(policy, head, list) {
184		if (!strcmp(policy->name, name))
185			return policy;
186	}
187	return NULL;
188}
189
190/**
191 * __policy_strn_find - find a policy that's name matches @len chars of @str
192 * @head: list to search  (NOT NULL)
193 * @str: string to search for  (NOT NULL)
194 * @len: length of match required
195 *
196 * Requires: rcu_read_lock be held
197 *
198 * Returns: unrefcounted policy that match @str or NULL if not found
199 *
200 * if @len == strlen(@strlen) then this is equiv to __policy_find
201 * other wise it allows searching for policy by a partial match of name
202 */
203static inline struct aa_policy *__policy_strn_find(struct list_head *head,
204					    const char *str, int len)
205{
206	struct aa_policy *policy;
207
208	list_for_each_entry_rcu(policy, head, list) {
209		if (aa_strneq(policy->name, str, len))
210			return policy;
211	}
212
213	return NULL;
214}
215
216bool aa_policy_init(struct aa_policy *policy, const char *prefix,
217		    const char *name, gfp_t gfp);
218void aa_policy_destroy(struct aa_policy *policy);
219
220
221/*
222 * fn_label_build - abstract out the build of a label transition
223 * @L: label the transition is being computed for
224 * @P: profile parameter derived from L by this macro, can be passed to FN
225 * @GFP: memory allocation type to use
226 * @FN: fn to call for each profile transition. @P is set to the profile
227 *
228 * Returns: new label on success
229 *          ERR_PTR if build @FN fails
230 *          NULL if label_build fails due to low memory conditions
231 *
232 * @FN must return a label or ERR_PTR on failure. NULL is not allowed
233 */
234#define fn_label_build(L, P, GFP, FN)					\
235({									\
236	__label__ __do_cleanup, __done;					\
237	struct aa_label *__new_;					\
238									\
239	if ((L)->size > 1) {						\
240		/* TODO: add cache of transitions already done */	\
241		struct label_it __i;					\
242		int __j, __k, __count;					\
243		DEFINE_VEC(label, __lvec);				\
244		DEFINE_VEC(profile, __pvec);				\
245		if (vec_setup(label, __lvec, (L)->size, (GFP)))	{	\
246			__new_ = NULL;					\
247			goto __done;					\
248		}							\
249		__j = 0;						\
250		label_for_each(__i, (L), (P)) {				\
251			__new_ = (FN);					\
252			AA_BUG(!__new_);				\
253			if (IS_ERR(__new_))				\
254				goto __do_cleanup;			\
255			__lvec[__j++] = __new_;				\
256		}							\
257		for (__j = __count = 0; __j < (L)->size; __j++)		\
258			__count += __lvec[__j]->size;			\
259		if (!vec_setup(profile, __pvec, __count, (GFP))) {	\
260			for (__j = __k = 0; __j < (L)->size; __j++) {	\
261				label_for_each(__i, __lvec[__j], (P))	\
262					__pvec[__k++] = aa_get_profile(P); \
263			}						\
264			__count -= aa_vec_unique(__pvec, __count, 0);	\
265			if (__count > 1) {				\
266				__new_ = aa_vec_find_or_create_label(__pvec,\
267						     __count, (GFP));	\
268				/* only fails if out of Mem */		\
269				if (!__new_)				\
270					__new_ = NULL;			\
271			} else						\
272				__new_ = aa_get_label(&__pvec[0]->label); \
273			vec_cleanup(profile, __pvec, __count);		\
274		} else							\
275			__new_ = NULL;					\
276__do_cleanup:								\
277		vec_cleanup(label, __lvec, (L)->size);			\
278	} else {							\
279		(P) = labels_profile(L);				\
280		__new_ = (FN);						\
281	}								\
282__done:									\
283	if (!__new_)							\
284		AA_DEBUG("label build failed\n");			\
285	(__new_);							\
286})
287
288
289#define __fn_build_in_ns(NS, P, NS_FN, OTHER_FN)			\
290({									\
291	struct aa_label *__new;						\
292	if ((P)->ns != (NS))						\
293		__new = (OTHER_FN);					\
294	else								\
295		__new = (NS_FN);					\
296	(__new);							\
297})
298
299#define fn_label_build_in_ns(L, P, GFP, NS_FN, OTHER_FN)		\
300({									\
301	fn_label_build((L), (P), (GFP),					\
302		__fn_build_in_ns(labels_ns(L), (P), (NS_FN), (OTHER_FN))); \
303})
304
305#endif /* __AA_LIB_H */