1 /* SPDX-License-Identifier: GPL-2.0-only */
2 /*
3  * AppArmor security module
4  *
5  * This file contains AppArmor contexts used to associate "labels" to objects.
6  *
7  * Copyright (C) 1998-2008 Novell/SUSE
8  * Copyright 2009-2010 Canonical Ltd.
9  */
10 
11 #ifndef __AA_CONTEXT_H
12 #define __AA_CONTEXT_H
13 
14 #include <linux/cred.h>
15 #include <linux/slab.h>
16 #include <linux/sched.h>
17 
18 #include "label.h"
19 #include "policy_ns.h"
20 #include "task.h"
21 
cred_label(const struct cred * cred)22 static inline struct aa_label *cred_label(const struct cred *cred)
23 {
24 	struct aa_label **blob = cred->security + apparmor_blob_sizes.lbs_cred;
25 
26 	AA_BUG(!blob);
27 	return *blob;
28 }
29 
set_cred_label(const struct cred * cred,struct aa_label * label)30 static inline void set_cred_label(const struct cred *cred,
31 				  struct aa_label *label)
32 {
33 	struct aa_label **blob = cred->security + apparmor_blob_sizes.lbs_cred;
34 
35 	AA_BUG(!blob);
36 	*blob = label;
37 }
38 
39 /**
40  * aa_cred_raw_label - obtain cred's label
41  * @cred: cred to obtain label from  (NOT NULL)
42  *
43  * Returns: confining label
44  *
45  * does NOT increment reference count
46  */
aa_cred_raw_label(const struct cred * cred)47 static inline struct aa_label *aa_cred_raw_label(const struct cred *cred)
48 {
49 	struct aa_label *label = cred_label(cred);
50 
51 	AA_BUG(!label);
52 	return label;
53 }
54 
55 /**
56  * aa_get_newest_cred_label - obtain the newest label on a cred
57  * @cred: cred to obtain label from (NOT NULL)
58  *
59  * Returns: newest version of confining label
60  */
aa_get_newest_cred_label(const struct cred * cred)61 static inline struct aa_label *aa_get_newest_cred_label(const struct cred *cred)
62 {
63 	return aa_get_newest_label(aa_cred_raw_label(cred));
64 }
65 
66 /**
67  * aa_current_raw_label - find the current tasks confining label
68  *
69  * Returns: up to date confining label or the ns unconfined label (NOT NULL)
70  *
71  * This fn will not update the tasks cred to the most up to date version
72  * of the label so it is safe to call when inside of locks.
73  */
aa_current_raw_label(void)74 static inline struct aa_label *aa_current_raw_label(void)
75 {
76 	return aa_cred_raw_label(current_cred());
77 }
78 
79 /**
80  * aa_get_current_label - get the newest version of the current tasks label
81  *
82  * Returns: newest version of confining label (NOT NULL)
83  *
84  * This fn will not update the tasks cred, so it is safe inside of locks
85  *
86  * The returned reference must be put with aa_put_label()
87  */
aa_get_current_label(void)88 static inline struct aa_label *aa_get_current_label(void)
89 {
90 	struct aa_label *l = aa_current_raw_label();
91 
92 	if (label_is_stale(l))
93 		return aa_get_newest_label(l);
94 	return aa_get_label(l);
95 }
96 
97 #define __end_current_label_crit_section(X) end_current_label_crit_section(X)
98 
99 /**
100  * end_label_crit_section - put a reference found with begin_current_label..
101  * @label: label reference to put
102  *
103  * Should only be used with a reference obtained with
104  * begin_current_label_crit_section and never used in situations where the
105  * task cred may be updated
106  */
end_current_label_crit_section(struct aa_label * label)107 static inline void end_current_label_crit_section(struct aa_label *label)
108 {
109 	if (label != aa_current_raw_label())
110 		aa_put_label(label);
111 }
112 
113 /**
114  * __begin_current_label_crit_section - current's confining label
115  *
116  * Returns: up to date confining label or the ns unconfined label (NOT NULL)
117  *
118  * safe to call inside locks
119  *
120  * The returned reference must be put with __end_current_label_crit_section()
121  * This must NOT be used if the task cred could be updated within the
122  * critical section between __begin_current_label_crit_section() ..
123  * __end_current_label_crit_section()
124  */
__begin_current_label_crit_section(void)125 static inline struct aa_label *__begin_current_label_crit_section(void)
126 {
127 	struct aa_label *label = aa_current_raw_label();
128 
129 	if (label_is_stale(label))
130 		label = aa_get_newest_label(label);
131 
132 	return label;
133 }
134 
135 /**
136  * begin_current_label_crit_section - current's confining label and update it
137  *
138  * Returns: up to date confining label or the ns unconfined label (NOT NULL)
139  *
140  * Not safe to call inside locks
141  *
142  * The returned reference must be put with end_current_label_crit_section()
143  * This must NOT be used if the task cred could be updated within the
144  * critical section between begin_current_label_crit_section() ..
145  * end_current_label_crit_section()
146  */
begin_current_label_crit_section(void)147 static inline struct aa_label *begin_current_label_crit_section(void)
148 {
149 	struct aa_label *label = aa_current_raw_label();
150 
151 	might_sleep();
152 
153 	if (label_is_stale(label)) {
154 		label = aa_get_newest_label(label);
155 		if (aa_replace_current_label(label) == 0)
156 			/* task cred will keep the reference */
157 			aa_put_label(label);
158 	}
159 
160 	return label;
161 }
162 
aa_get_current_ns(void)163 static inline struct aa_ns *aa_get_current_ns(void)
164 {
165 	struct aa_label *label;
166 	struct aa_ns *ns;
167 
168 	label  = __begin_current_label_crit_section();
169 	ns = aa_get_ns(labels_ns(label));
170 	__end_current_label_crit_section(label);
171 
172 	return ns;
173 }
174 
175 #endif /* __AA_CONTEXT_H */
176