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 */
28struct 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
37static inline void mls_context_init(struct context *c)
38{
39	memset(&c->range, 0, sizeof(c->range));
40}
41
42static 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);
56out:
57	return rc;
58}
59
60/*
61 * Sets both levels in the MLS range of 'dst' to the low level of 'src'.
62 */
63static 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);
77out:
78	return rc;
79}
80
81/*
82 * Sets both levels in the MLS range of 'dst' to the high level of 'src'.
83 */
84static 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);
98out:
99	return rc;
100}
101
102static 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
131out:
132	return rc;
133}
134
135static 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
144static 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
151static inline void context_init(struct context *c)
152{
153	memset(c, 0, sizeof(*c));
154}
155
156static 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
182static 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
191static 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
202u32 context_compute_hash(const struct context *c);
203
204#endif /* _SS_CONTEXT_H_ */
205