1/*
  2 * A security context is a set of security attributes
  3 * associated with each subject and object controlled
  4 * by the security policy.  Security contexts are
  5  * externally represented as variable-length strings
  6 * that can be interpreted by a user or application
  7 * with an understanding of the security policy.
  8 * Internally, the security server uses a simple
  9 * structure.  This structure is private to the
 10 * security server and can be changed without affecting
 11 * clients of the security server.
 12 *
 13 * Author : Stephen Smalley, <sds@epoch.ncsc.mil>
 14 */
 15#ifndef _SS_CONTEXT_H_
 16#define _SS_CONTEXT_H_
 17
 18#include "ebitmap.h"
 19#include "mls_types.h"
 20#include "security.h"
 21
 22/*
 23 * A security context consists of an authenticated user
 24 * identity, a role, a type and a MLS range.
 25 */
 26struct context {
 27	u32 user;
 28	u32 role;
 29	u32 type;
 30	u32 len;        /* length of string in bytes */
 31	struct mls_range range;
 32	char *str;	/* string representation if context cannot be mapped. */
 33};
 34
 35static inline void mls_context_init(struct context *c)
 36{
 37	memset(&c->range, 0, sizeof(c->range));
 38}
 39
 40static inline int mls_context_cpy(struct context *dst, struct context *src)
 41{
 42	int rc;
 43
 44	dst->range.level[0].sens = src->range.level[0].sens;
 45	rc = ebitmap_cpy(&dst->range.level[0].cat, &src->range.level[0].cat);
 46	if (rc)
 47		goto out;
 48
 49	dst->range.level[1].sens = src->range.level[1].sens;
 50	rc = ebitmap_cpy(&dst->range.level[1].cat, &src->range.level[1].cat);
 51	if (rc)
 52		ebitmap_destroy(&dst->range.level[0].cat);
 53out:
 54	return rc;
 55}
 56
 57/*
 58 * Sets both levels in the MLS range of 'dst' to the low level of 'src'.
 59 */
 60static inline int mls_context_cpy_low(struct context *dst, struct context *src)
 61{
 62	int rc;
 63
 64	dst->range.level[0].sens = src->range.level[0].sens;
 65	rc = ebitmap_cpy(&dst->range.level[0].cat, &src->range.level[0].cat);
 66	if (rc)
 67		goto out;
 68
 69	dst->range.level[1].sens = src->range.level[0].sens;
 70	rc = ebitmap_cpy(&dst->range.level[1].cat, &src->range.level[0].cat);
 71	if (rc)
 72		ebitmap_destroy(&dst->range.level[0].cat);
 73out:
 74	return rc;
 75}
 76
 77/*
 78 * Sets both levels in the MLS range of 'dst' to the high level of 'src'.
 79 */
 80static inline int mls_context_cpy_high(struct context *dst, struct context *src)
 81{
 82	int rc;
 83
 84	dst->range.level[0].sens = src->range.level[1].sens;
 85	rc = ebitmap_cpy(&dst->range.level[0].cat, &src->range.level[1].cat);
 86	if (rc)
 87		goto out;
 88
 89	dst->range.level[1].sens = src->range.level[1].sens;
 90	rc = ebitmap_cpy(&dst->range.level[1].cat, &src->range.level[1].cat);
 91	if (rc)
 92		ebitmap_destroy(&dst->range.level[0].cat);
 93out:
 94	return rc;
 95}
 96
 97static inline int mls_context_cmp(struct context *c1, struct context *c2)
 98{
 99	return ((c1->range.level[0].sens == c2->range.level[0].sens) &&
100		ebitmap_cmp(&c1->range.level[0].cat, &c2->range.level[0].cat) &&
101		(c1->range.level[1].sens == c2->range.level[1].sens) &&
102		ebitmap_cmp(&c1->range.level[1].cat, &c2->range.level[1].cat));
103}
104
105static inline void mls_context_destroy(struct context *c)
106{
107	ebitmap_destroy(&c->range.level[0].cat);
108	ebitmap_destroy(&c->range.level[1].cat);
109	mls_context_init(c);
110}
111
112static inline void context_init(struct context *c)
113{
114	memset(c, 0, sizeof(*c));
115}
116
117static inline int context_cpy(struct context *dst, struct context *src)
118{
119	int rc;
120
121	dst->user = src->user;
122	dst->role = src->role;
123	dst->type = src->type;
124	if (src->str) {
125		dst->str = kstrdup(src->str, GFP_ATOMIC);
126		if (!dst->str)
127			return -ENOMEM;
128		dst->len = src->len;
129	} else {
130		dst->str = NULL;
131		dst->len = 0;
132	}
133	rc = mls_context_cpy(dst, src);
134	if (rc) {
135		kfree(dst->str);
136		return rc;
137	}
138	return 0;
139}
140
141static inline void context_destroy(struct context *c)
142{
143	c->user = c->role = c->type = 0;
144	kfree(c->str);
145	c->str = NULL;
146	c->len = 0;
147	mls_context_destroy(c);
148}
149
150static inline int context_cmp(struct context *c1, struct context *c2)
151{
152	if (c1->len && c2->len)
153		return (c1->len == c2->len && !strcmp(c1->str, c2->str));
154	if (c1->len || c2->len)
155		return 0;
156	return ((c1->user == c2->user) &&
157		(c1->role == c2->role) &&
158		(c1->type == c2->type) &&
159		mls_context_cmp(c1, c2));
160}
161
162#endif	/* _SS_CONTEXT_H_ */
163