1 /* SPDX-License-Identifier: GPL-2.0 */
2 /*
3 * A security context is a set of security attributes
4 * associated with each subject and object controlled
5 * by the security policy. Security contexts are
6 * externally represented as variable-length strings
7 * that can be interpreted by a user or application
8 * with an understanding of the security policy.
9 * Internally, the security server uses a simple
10 * structure. This structure is private to the
11 * security server and can be changed without affecting
12 * clients of the security server.
13 *
14 * Author : Stephen Smalley, <stephen.smalley.work@gmail.com>
15 */
16
17 #ifndef _SS_CONTEXT_H_
18 #define _SS_CONTEXT_H_
19
20 #include "ebitmap.h"
21 #include "mls_types.h"
22 #include "security.h"
23
24 /*
25 * A security context consists of an authenticated user
26 * identity, a role, a type and a MLS range.
27 */
28 struct context {
29 u32 user;
30 u32 role;
31 u32 type;
32 u32 len; /* length of string in bytes */
33 struct mls_range range;
34 char *str; /* string representation if context cannot be mapped. */
35 };
36
37 static inline void mls_context_init(struct context *c)
38 {
39 memset(&c->range, 0, sizeof(c->range));
40 }
41
42 static inline int mls_context_cpy(struct context *dst,
43 const struct context *src)
44 {
45 int rc;
46
47 dst->range.level[0].sens = src->range.level[0].sens;
48 rc = ebitmap_cpy(&dst->range.level[0].cat, &src->range.level[0].cat);
49 if (rc)
50 goto out;
51
52 dst->range.level[1].sens = src->range.level[1].sens;
53 rc = ebitmap_cpy(&dst->range.level[1].cat, &src->range.level[1].cat);
54 if (rc)
55 ebitmap_destroy(&dst->range.level[0].cat);
56 out:
57 return rc;
58 }
59
60 /*
61 * Sets both levels in the MLS range of 'dst' to the low level of 'src'.
62 */
63 static inline int mls_context_cpy_low(struct context *dst,
64 const struct context *src)
65 {
66 int rc;
67
68 dst->range.level[0].sens = src->range.level[0].sens;
69 rc = ebitmap_cpy(&dst->range.level[0].cat, &src->range.level[0].cat);
70 if (rc)
71 goto out;
72
73 dst->range.level[1].sens = src->range.level[0].sens;
74 rc = ebitmap_cpy(&dst->range.level[1].cat, &src->range.level[0].cat);
75 if (rc)
76 ebitmap_destroy(&dst->range.level[0].cat);
77 out:
78 return rc;
79 }
80
81 /*
82 * Sets both levels in the MLS range of 'dst' to the high level of 'src'.
83 */
84 static inline int mls_context_cpy_high(struct context *dst,
85 const struct context *src)
86 {
87 int rc;
88
89 dst->range.level[0].sens = src->range.level[1].sens;
90 rc = ebitmap_cpy(&dst->range.level[0].cat, &src->range.level[1].cat);
91 if (rc)
92 goto out;
93
94 dst->range.level[1].sens = src->range.level[1].sens;
95 rc = ebitmap_cpy(&dst->range.level[1].cat, &src->range.level[1].cat);
96 if (rc)
97 ebitmap_destroy(&dst->range.level[0].cat);
98 out:
99 return rc;
100 }
101
102 static inline int mls_context_glblub(struct context *dst,
103 const struct context *c1,
104 const struct context *c2)
105 {
106 struct mls_range *dr = &dst->range;
107 const struct mls_range *r1 = &c1->range, *r2 = &c2->range;
108 int rc = 0;
109
110 if (r1->level[1].sens < r2->level[0].sens ||
111 r2->level[1].sens < r1->level[0].sens)
112 /* These ranges have no common sensitivities */
113 return -EINVAL;
114
115 /* Take the greatest of the low */
116 dr->level[0].sens = max(r1->level[0].sens, r2->level[0].sens);
117
118 /* Take the least of the high */
119 dr->level[1].sens = min(r1->level[1].sens, r2->level[1].sens);
120
121 rc = ebitmap_and(&dr->level[0].cat, &r1->level[0].cat,
122 &r2->level[0].cat);
123 if (rc)
124 goto out;
125
126 rc = ebitmap_and(&dr->level[1].cat, &r1->level[1].cat,
127 &r2->level[1].cat);
128 if (rc)
129 goto out;
130
131 out:
132 return rc;
133 }
134
135 static inline int mls_context_cmp(const struct context *c1,
136 const struct context *c2)
137 {
138 return ((c1->range.level[0].sens == c2->range.level[0].sens) &&
139 ebitmap_cmp(&c1->range.level[0].cat, &c2->range.level[0].cat) &&
140 (c1->range.level[1].sens == c2->range.level[1].sens) &&
141 ebitmap_cmp(&c1->range.level[1].cat, &c2->range.level[1].cat));
142 }
143
144 static inline void mls_context_destroy(struct context *c)
145 {
146 ebitmap_destroy(&c->range.level[0].cat);
147 ebitmap_destroy(&c->range.level[1].cat);
148 mls_context_init(c);
149 }
150
151 static inline void context_init(struct context *c)
152 {
153 memset(c, 0, sizeof(*c));
154 }
155
156 static inline int context_cpy(struct context *dst, const struct context *src)
157 {
158 int rc;
159
160 dst->user = src->user;
161 dst->role = src->role;
162 dst->type = src->type;
163 if (src->str) {
164 dst->str = kstrdup(src->str, GFP_ATOMIC);
165 if (!dst->str)
166 return -ENOMEM;
167 dst->len = src->len;
168 } else {
169 dst->str = NULL;
170 dst->len = 0;
171 }
172 rc = mls_context_cpy(dst, src);
173 if (rc) {
174 kfree(dst->str);
175 dst->str = NULL;
176 dst->len = 0;
177 return rc;
178 }
179 return 0;
180 }
181
182 static inline void context_destroy(struct context *c)
183 {
184 c->user = c->role = c->type = 0;
185 kfree(c->str);
186 c->str = NULL;
187 c->len = 0;
188 mls_context_destroy(c);
189 }
190
191 static inline int context_cmp(const struct context *c1,
192 const struct context *c2)
193 {
194 if (c1->len && c2->len)
195 return (c1->len == c2->len && !strcmp(c1->str, c2->str));
196 if (c1->len || c2->len)
197 return 0;
198 return ((c1->user == c2->user) && (c1->role == c2->role) &&
199 (c1->type == c2->type) && mls_context_cmp(c1, c2));
200 }
201
202 u32 context_compute_hash(const struct context *c);
203
204 #endif /* _SS_CONTEXT_H_ */
205
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