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/* SPDX-License-Identifier: GPL-2.0 */
/*
* A security context is a set of security attributes
* associated with each subject and object controlled
* by the security policy. Security contexts are
* externally represented as variable-length strings
* that can be interpreted by a user or application
* with an understanding of the security policy.
* Internally, the security server uses a simple
* structure. This structure is private to the
* security server and can be changed without affecting
* clients of the security server.
*
* Author : Stephen Smalley, <sds@tycho.nsa.gov>
*/
#ifndef _SS_CONTEXT_H_
#define _SS_CONTEXT_H_
#include "ebitmap.h"
#include "mls_types.h"
#include "security.h"
/*
* A security context consists of an authenticated user
* identity, a role, a type and a MLS range.
*/
struct context {
u32 user;
u32 role;
u32 type;
u32 len; /* length of string in bytes */
struct mls_range range;
char *str; /* string representation if context cannot be mapped. */
u32 hash; /* a hash of the string representation */
};
static inline void mls_context_init(struct context *c)
{
memset(&c->range, 0, sizeof(c->range));
}
static inline int mls_context_cpy(struct context *dst, struct context *src)
{
int rc;
dst->range.level[0].sens = src->range.level[0].sens;
rc = ebitmap_cpy(&dst->range.level[0].cat, &src->range.level[0].cat);
if (rc)
goto out;
dst->range.level[1].sens = src->range.level[1].sens;
rc = ebitmap_cpy(&dst->range.level[1].cat, &src->range.level[1].cat);
if (rc)
ebitmap_destroy(&dst->range.level[0].cat);
out:
return rc;
}
/*
* Sets both levels in the MLS range of 'dst' to the low level of 'src'.
*/
static inline int mls_context_cpy_low(struct context *dst, struct context *src)
{
int rc;
dst->range.level[0].sens = src->range.level[0].sens;
rc = ebitmap_cpy(&dst->range.level[0].cat, &src->range.level[0].cat);
if (rc)
goto out;
dst->range.level[1].sens = src->range.level[0].sens;
rc = ebitmap_cpy(&dst->range.level[1].cat, &src->range.level[0].cat);
if (rc)
ebitmap_destroy(&dst->range.level[0].cat);
out:
return rc;
}
/*
* Sets both levels in the MLS range of 'dst' to the high level of 'src'.
*/
static inline int mls_context_cpy_high(struct context *dst, struct context *src)
{
int rc;
dst->range.level[0].sens = src->range.level[1].sens;
rc = ebitmap_cpy(&dst->range.level[0].cat, &src->range.level[1].cat);
if (rc)
goto out;
dst->range.level[1].sens = src->range.level[1].sens;
rc = ebitmap_cpy(&dst->range.level[1].cat, &src->range.level[1].cat);
if (rc)
ebitmap_destroy(&dst->range.level[0].cat);
out:
return rc;
}
static inline int mls_context_glblub(struct context *dst,
struct context *c1, struct context *c2)
{
struct mls_range *dr = &dst->range, *r1 = &c1->range, *r2 = &c2->range;
int rc = 0;
if (r1->level[1].sens < r2->level[0].sens ||
r2->level[1].sens < r1->level[0].sens)
/* These ranges have no common sensitivities */
return -EINVAL;
/* Take the greatest of the low */
dr->level[0].sens = max(r1->level[0].sens, r2->level[0].sens);
/* Take the least of the high */
dr->level[1].sens = min(r1->level[1].sens, r2->level[1].sens);
rc = ebitmap_and(&dr->level[0].cat,
&r1->level[0].cat, &r2->level[0].cat);
if (rc)
goto out;
rc = ebitmap_and(&dr->level[1].cat,
&r1->level[1].cat, &r2->level[1].cat);
if (rc)
goto out;
out:
return rc;
}
static inline int mls_context_cmp(struct context *c1, struct context *c2)
{
return ((c1->range.level[0].sens == c2->range.level[0].sens) &&
ebitmap_cmp(&c1->range.level[0].cat, &c2->range.level[0].cat) &&
(c1->range.level[1].sens == c2->range.level[1].sens) &&
ebitmap_cmp(&c1->range.level[1].cat, &c2->range.level[1].cat));
}
static inline void mls_context_destroy(struct context *c)
{
ebitmap_destroy(&c->range.level[0].cat);
ebitmap_destroy(&c->range.level[1].cat);
mls_context_init(c);
}
static inline void context_init(struct context *c)
{
memset(c, 0, sizeof(*c));
}
static inline int context_cpy(struct context *dst, struct context *src)
{
int rc;
dst->user = src->user;
dst->role = src->role;
dst->type = src->type;
if (src->str) {
dst->str = kstrdup(src->str, GFP_ATOMIC);
if (!dst->str)
return -ENOMEM;
dst->len = src->len;
} else {
dst->str = NULL;
dst->len = 0;
}
rc = mls_context_cpy(dst, src);
if (rc) {
kfree(dst->str);
return rc;
}
dst->hash = src->hash;
return 0;
}
static inline void context_destroy(struct context *c)
{
c->user = c->role = c->type = c->hash = 0;
kfree(c->str);
c->str = NULL;
c->len = 0;
mls_context_destroy(c);
}
static inline int context_cmp(struct context *c1, struct context *c2)
{
if (c1->hash && c2->hash && (c1->hash != c2->hash))
return 0;
if (c1->len && c2->len)
return (c1->len == c2->len && !strcmp(c1->str, c2->str));
if (c1->len || c2->len)
return 0;
return ((c1->user == c2->user) &&
(c1->role == c2->role) &&
(c1->type == c2->type) &&
mls_context_cmp(c1, c2));
}
u32 context_compute_hash(const struct context *c);
static inline void context_add_hash(struct context *context)
{
context->hash = context_compute_hash(context);
}
#endif /* _SS_CONTEXT_H_ */
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