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 };
35 
mls_context_init(struct context * c)36 static inline void mls_context_init(struct context *c)
37 {
38 	memset(&c->range, 0, sizeof(c->range));
39 }
40 
mls_context_cpy(struct context * dst,const struct context * src)41 static inline int mls_context_cpy(struct context *dst, const struct context *src)
42 {
43 	int rc;
44 
45 	dst->range.level[0].sens = src->range.level[0].sens;
46 	rc = ebitmap_cpy(&dst->range.level[0].cat, &src->range.level[0].cat);
47 	if (rc)
48 		goto out;
49 
50 	dst->range.level[1].sens = src->range.level[1].sens;
51 	rc = ebitmap_cpy(&dst->range.level[1].cat, &src->range.level[1].cat);
52 	if (rc)
53 		ebitmap_destroy(&dst->range.level[0].cat);
54 out:
55 	return rc;
56 }
57 
58 /*
59  * Sets both levels in the MLS range of 'dst' to the low level of 'src'.
60  */
mls_context_cpy_low(struct context * dst,const struct context * src)61 static inline int mls_context_cpy_low(struct context *dst, const struct context *src)
62 {
63 	int rc;
64 
65 	dst->range.level[0].sens = src->range.level[0].sens;
66 	rc = ebitmap_cpy(&dst->range.level[0].cat, &src->range.level[0].cat);
67 	if (rc)
68 		goto out;
69 
70 	dst->range.level[1].sens = src->range.level[0].sens;
71 	rc = ebitmap_cpy(&dst->range.level[1].cat, &src->range.level[0].cat);
72 	if (rc)
73 		ebitmap_destroy(&dst->range.level[0].cat);
74 out:
75 	return rc;
76 }
77 
78 /*
79  * Sets both levels in the MLS range of 'dst' to the high level of 'src'.
80  */
mls_context_cpy_high(struct context * dst,const struct context * src)81 static inline int mls_context_cpy_high(struct context *dst, const struct context *src)
82 {
83 	int rc;
84 
85 	dst->range.level[0].sens = src->range.level[1].sens;
86 	rc = ebitmap_cpy(&dst->range.level[0].cat, &src->range.level[1].cat);
87 	if (rc)
88 		goto out;
89 
90 	dst->range.level[1].sens = src->range.level[1].sens;
91 	rc = ebitmap_cpy(&dst->range.level[1].cat, &src->range.level[1].cat);
92 	if (rc)
93 		ebitmap_destroy(&dst->range.level[0].cat);
94 out:
95 	return rc;
96 }
97 
98 
mls_context_glblub(struct context * dst,const struct context * c1,const struct context * c2)99 static inline int mls_context_glblub(struct context *dst,
100 				     const struct context *c1, const struct context *c2)
101 {
102 	struct mls_range *dr = &dst->range;
103 	const struct mls_range *r1 = &c1->range, *r2 = &c2->range;
104 	int rc = 0;
105 
106 	if (r1->level[1].sens < r2->level[0].sens ||
107 	    r2->level[1].sens < r1->level[0].sens)
108 		/* These ranges have no common sensitivities */
109 		return -EINVAL;
110 
111 	/* Take the greatest of the low */
112 	dr->level[0].sens = max(r1->level[0].sens, r2->level[0].sens);
113 
114 	/* Take the least of the high */
115 	dr->level[1].sens = min(r1->level[1].sens, r2->level[1].sens);
116 
117 	rc = ebitmap_and(&dr->level[0].cat,
118 			 &r1->level[0].cat, &r2->level[0].cat);
119 	if (rc)
120 		goto out;
121 
122 	rc = ebitmap_and(&dr->level[1].cat,
123 			 &r1->level[1].cat, &r2->level[1].cat);
124 	if (rc)
125 		goto out;
126 
127 out:
128 	return rc;
129 }
130 
mls_context_cmp(const struct context * c1,const struct context * c2)131 static inline int mls_context_cmp(const struct context *c1, const struct context *c2)
132 {
133 	return ((c1->range.level[0].sens == c2->range.level[0].sens) &&
134 		ebitmap_cmp(&c1->range.level[0].cat, &c2->range.level[0].cat) &&
135 		(c1->range.level[1].sens == c2->range.level[1].sens) &&
136 		ebitmap_cmp(&c1->range.level[1].cat, &c2->range.level[1].cat));
137 }
138 
mls_context_destroy(struct context * c)139 static inline void mls_context_destroy(struct context *c)
140 {
141 	ebitmap_destroy(&c->range.level[0].cat);
142 	ebitmap_destroy(&c->range.level[1].cat);
143 	mls_context_init(c);
144 }
145 
context_init(struct context * c)146 static inline void context_init(struct context *c)
147 {
148 	memset(c, 0, sizeof(*c));
149 }
150 
context_cpy(struct context * dst,const struct context * src)151 static inline int context_cpy(struct context *dst, const struct context *src)
152 {
153 	int rc;
154 
155 	dst->user = src->user;
156 	dst->role = src->role;
157 	dst->type = src->type;
158 	if (src->str) {
159 		dst->str = kstrdup(src->str, GFP_ATOMIC);
160 		if (!dst->str)
161 			return -ENOMEM;
162 		dst->len = src->len;
163 	} else {
164 		dst->str = NULL;
165 		dst->len = 0;
166 	}
167 	rc = mls_context_cpy(dst, src);
168 	if (rc) {
169 		kfree(dst->str);
170 		return rc;
171 	}
172 	return 0;
173 }
174 
context_destroy(struct context * c)175 static inline void context_destroy(struct context *c)
176 {
177 	c->user = c->role = c->type = 0;
178 	kfree(c->str);
179 	c->str = NULL;
180 	c->len = 0;
181 	mls_context_destroy(c);
182 }
183 
context_cmp(const struct context * c1,const struct context * c2)184 static inline int context_cmp(const struct context *c1, const struct context *c2)
185 {
186 	if (c1->len && c2->len)
187 		return (c1->len == c2->len && !strcmp(c1->str, c2->str));
188 	if (c1->len || c2->len)
189 		return 0;
190 	return ((c1->user == c2->user) &&
191 		(c1->role == c2->role) &&
192 		(c1->type == c2->type) &&
193 		mls_context_cmp(c1, c2));
194 }
195 
196 u32 context_compute_hash(const struct context *c);
197 
198 #endif	/* _SS_CONTEXT_H_ */
199 
200