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, <sds@tycho.nsa.gov>
15 */
16 #ifndef _SS_CONTEXT_H_
17 #define _SS_CONTEXT_H_
18
19 #include "ebitmap.h"
20 #include "mls_types.h"
21 #include "security.h"
22
23 /*
24 * A security context consists of an authenticated user
25 * identity, a role, a type and a MLS range.
26 */
27 struct context {
28 u32 user;
29 u32 role;
30 u32 type;
31 u32 len; /* length of string in bytes */
32 struct mls_range range;
33 char *str; /* string representation if context cannot be mapped. */
34 u32 hash; /* a hash of the string representation */
35 };
36
mls_context_init(struct context * c)37 static inline void mls_context_init(struct context *c)
38 {
39 memset(&c->range, 0, sizeof(c->range));
40 }
41
mls_context_cpy(struct context * dst,struct context * src)42 static inline int mls_context_cpy(struct context *dst, struct context *src)
43 {
44 int rc;
45
46 dst->range.level[0].sens = src->range.level[0].sens;
47 rc = ebitmap_cpy(&dst->range.level[0].cat, &src->range.level[0].cat);
48 if (rc)
49 goto out;
50
51 dst->range.level[1].sens = src->range.level[1].sens;
52 rc = ebitmap_cpy(&dst->range.level[1].cat, &src->range.level[1].cat);
53 if (rc)
54 ebitmap_destroy(&dst->range.level[0].cat);
55 out:
56 return rc;
57 }
58
59 /*
60 * Sets both levels in the MLS range of 'dst' to the low level of 'src'.
61 */
mls_context_cpy_low(struct context * dst,struct context * src)62 static inline int mls_context_cpy_low(struct context *dst, struct context *src)
63 {
64 int rc;
65
66 dst->range.level[0].sens = src->range.level[0].sens;
67 rc = ebitmap_cpy(&dst->range.level[0].cat, &src->range.level[0].cat);
68 if (rc)
69 goto out;
70
71 dst->range.level[1].sens = src->range.level[0].sens;
72 rc = ebitmap_cpy(&dst->range.level[1].cat, &src->range.level[0].cat);
73 if (rc)
74 ebitmap_destroy(&dst->range.level[0].cat);
75 out:
76 return rc;
77 }
78
79 /*
80 * Sets both levels in the MLS range of 'dst' to the high level of 'src'.
81 */
mls_context_cpy_high(struct context * dst,struct context * src)82 static inline int mls_context_cpy_high(struct context *dst, struct context *src)
83 {
84 int rc;
85
86 dst->range.level[0].sens = src->range.level[1].sens;
87 rc = ebitmap_cpy(&dst->range.level[0].cat, &src->range.level[1].cat);
88 if (rc)
89 goto out;
90
91 dst->range.level[1].sens = src->range.level[1].sens;
92 rc = ebitmap_cpy(&dst->range.level[1].cat, &src->range.level[1].cat);
93 if (rc)
94 ebitmap_destroy(&dst->range.level[0].cat);
95 out:
96 return rc;
97 }
98
mls_context_cmp(struct context * c1,struct context * c2)99 static inline int mls_context_cmp(struct context *c1, struct context *c2)
100 {
101 return ((c1->range.level[0].sens == c2->range.level[0].sens) &&
102 ebitmap_cmp(&c1->range.level[0].cat, &c2->range.level[0].cat) &&
103 (c1->range.level[1].sens == c2->range.level[1].sens) &&
104 ebitmap_cmp(&c1->range.level[1].cat, &c2->range.level[1].cat));
105 }
106
mls_context_destroy(struct context * c)107 static inline void mls_context_destroy(struct context *c)
108 {
109 ebitmap_destroy(&c->range.level[0].cat);
110 ebitmap_destroy(&c->range.level[1].cat);
111 mls_context_init(c);
112 }
113
context_init(struct context * c)114 static inline void context_init(struct context *c)
115 {
116 memset(c, 0, sizeof(*c));
117 }
118
context_cpy(struct context * dst,struct context * src)119 static inline int context_cpy(struct context *dst, struct context *src)
120 {
121 int rc;
122
123 dst->user = src->user;
124 dst->role = src->role;
125 dst->type = src->type;
126 if (src->str) {
127 dst->str = kstrdup(src->str, GFP_ATOMIC);
128 if (!dst->str)
129 return -ENOMEM;
130 dst->len = src->len;
131 } else {
132 dst->str = NULL;
133 dst->len = 0;
134 }
135 rc = mls_context_cpy(dst, src);
136 if (rc) {
137 kfree(dst->str);
138 return rc;
139 }
140 dst->hash = src->hash;
141 return 0;
142 }
143
context_destroy(struct context * c)144 static inline void context_destroy(struct context *c)
145 {
146 c->user = c->role = c->type = c->hash = 0;
147 kfree(c->str);
148 c->str = NULL;
149 c->len = 0;
150 mls_context_destroy(c);
151 }
152
context_cmp(struct context * c1,struct context * c2)153 static inline int context_cmp(struct context *c1, struct context *c2)
154 {
155 if (c1->hash && c2->hash && (c1->hash != c2->hash))
156 return 0;
157 if (c1->len && c2->len)
158 return (c1->len == c2->len && !strcmp(c1->str, c2->str));
159 if (c1->len || c2->len)
160 return 0;
161 return ((c1->user == c2->user) &&
162 (c1->role == c2->role) &&
163 (c1->type == c2->type) &&
164 mls_context_cmp(c1, c2));
165 }
166
context_compute_hash(const char * s)167 static inline unsigned int context_compute_hash(const char *s)
168 {
169 return full_name_hash(NULL, s, strlen(s));
170 }
171
172 #endif /* _SS_CONTEXT_H_ */
173
174