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#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 */
27struct 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
36static inline void mls_context_init(struct context *c)
37{
38	memset(&c->range, 0, sizeof(c->range));
39}
40
41static 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);
54out:
55	return rc;
56}
57
58/*
59 * Sets both levels in the MLS range of 'dst' to the low level of 'src'.
60 */
61static 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);
74out:
75	return rc;
76}
77
78/*
79 * Sets both levels in the MLS range of 'dst' to the high level of 'src'.
80 */
81static 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);
94out:
95	return rc;
96}
97
98
99static 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
127out:
128	return rc;
129}
130
131static 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
139static 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
146static inline void context_init(struct context *c)
147{
148	memset(c, 0, sizeof(*c));
149}
150
151static 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		dst->str = NULL;
171		dst->len = 0;
172		return rc;
173	}
174	return 0;
175}
176
177static inline void context_destroy(struct context *c)
178{
179	c->user = c->role = c->type = 0;
180	kfree(c->str);
181	c->str = NULL;
182	c->len = 0;
183	mls_context_destroy(c);
184}
185
186static inline int context_cmp(const struct context *c1, const struct context *c2)
187{
188	if (c1->len && c2->len)
189		return (c1->len == c2->len && !strcmp(c1->str, c2->str));
190	if (c1->len || c2->len)
191		return 0;
192	return ((c1->user == c2->user) &&
193		(c1->role == c2->role) &&
194		(c1->type == c2->type) &&
195		mls_context_cmp(c1, c2));
196}
197
198u32 context_compute_hash(const struct context *c);
199
200#endif	/* _SS_CONTEXT_H_ */
201
202