context.h

Go to the documentation of this file.

/*
 * 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, <[email protected]>
 */
#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. */
};

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_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;
    }
    return 0;
}

static inline void context_destroy(struct context *c)
{
    c->user = c->role = c->type = 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->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));
}

#endif  /* _SS_CONTEXT_H_ */