selinux/ss/context.c

0001 // SPDX-License-Identifier: GPL-2.0
0002 /*
0003  * Implementations of the security context functions.
0004  *
0005  * Author: Ondrej Mosnacek <omosnacek@gmail.com>
0006  * Copyright (C) 2020 Red Hat, Inc.
0007  */
0008
0009 #include <linux/jhash.h>
0010
0011 #include "context.h"
0012 #include "mls.h"
0013
0014 u32 context_compute_hash(const struct context *c)
0015 {
0016     u32 hash = 0;
0017
0018     /*
0019      * If a context is invalid, it will always be represented by a
0020      * context struct with only the len & str set (and vice versa)
0021      * under a given policy. Since context structs from different
0022      * policies should never meet, it is safe to hash valid and
0023      * invalid contexts differently. The context_cmp() function
0024      * already operates under the same assumption.
0025      */
0026     if (c->len)
0027         return full_name_hash(NULL, c->str, c->len);
0028
0029     hash = jhash_3words(c->user, c->role, c->type, hash);
0030     hash = mls_range_hash(&c->range, hash);
0031     return hash;
0032 }