path: root/net/sctp/auth.c

// SPDX-License-Identifier: GPL-2.0-or-later
/* SCTP kernel implementation
 * (C) Copyright 2007 Hewlett-Packard Development Company, L.P.
 *
 * This file is part of the SCTP kernel implementation
 *
 * Please send any bug reports or fixes you make to the
 * email address(es):
 *    lksctp developers <linux-sctp@vger.kernel.org>
 *
 * Written or modified by:
 *   Vlad Yasevich     <vladislav.yasevich@hp.com>
 */

#include <crypto/hash.h>
#include <linux/slab.h>
#include <linux/types.h>
#include <linux/scatterlist.h>
#include <net/sctp/sctp.h>
#include <net/sctp/auth.h>

static struct sctp_hmac sctp_hmac_list[SCTP_AUTH_NUM_HMACS] = {
	{
		/* id 0 is reserved.  as all 0 */
		.hmac_id = SCTP_AUTH_HMAC_ID_RESERVED_0,
	},
	{
		.hmac_id = SCTP_AUTH_HMAC_ID_SHA1,
		.hmac_name = "hmac(sha1)",
		.hmac_len = SCTP_SHA1_SIG_SIZE,
	},
	{
		/* id 2 is reserved as well */
		.hmac_id = SCTP_AUTH_HMAC_ID_RESERVED_2,
	},
#if IS_ENABLED(CONFIG_CRYPTO_SHA256)
	{
		.hmac_id = SCTP_AUTH_HMAC_ID_SHA256,
		.hmac_name = "hmac(sha256)",
		.hmac_len = SCTP_SHA256_SIG_SIZE,
	}
#endif
};


void sctp_auth_key_put(struct sctp_auth_bytes *key)
{
	if (!key)
		return;

	if (refcount_dec_and_test(&key->refcnt)) {
		kfree_sensitive(key);
		SCTP_DBG_OBJCNT_DEC(keys);
	}
}

/* Create a new key structure of a given length */
static struct sctp_auth_bytes *sctp_auth_create_key(__u32 key_len, gfp_t gfp)
{
	struct sctp_auth_bytes *key;

	/* Verify that we are not going to overflow INT_MAX */
	if (key_len > (INT_MAX - sizeof(struct sctp_auth_bytes)))
		return NULL;

	/* Allocate the shared key */
	key = kmalloc(sizeof(struct sctp_auth_bytes) + key_len, gfp);
	if (!key)
		return NULL;

	key->len = key_len;
	refcount_set(&key->refcnt, 1);
	SCTP_DBG_OBJCNT_INC(keys);

	return key;
}

/* Create a new shared key container with a give key id */
struct sctp_shared_key *sctp_auth_shkey_create(__u16 key_id, gfp_t gfp)
{
	struct sctp_shared_key *new;

	/* Allocate the shared key container */
	new = kzalloc(sizeof(struct sctp_shared_key), gfp);
	if (!new)
		return NULL;

	INIT_LIST_HEAD(&new->key_list);
	refcount_set(&new->refcnt, 1);
	new->key_id = key_id;

	return new;
}

/* Free the shared key structure */
static void sctp_auth_shkey_destroy(struct sctp_shared_key *sh_key)
{
	BUG_ON(!list_empty(&sh_key->key_list));
	sctp_auth_key_put(sh_key->key);
	sh_key->key = NULL;
	kfree(sh_key);
}

void sctp_auth_shkey_release(struct sctp_shared_key *sh_key)
{
	if (refcount_dec_and_test(&sh_key->refcnt))
		sctp_auth_shkey_destroy(sh_key);
}

void sctp_auth_shkey_hold(struct sctp_shared_key *sh_key)
{
	refcount_inc(&sh_key->refcnt);
}

/* Destroy the entire key list.  This is done during the
 * associon and endpoint free process.
 */
void sctp_auth_destroy_keys(struct list_head *keys)
{
	struct sctp_shared_key *ep_key;
	struct sctp_shared_key *tmp;

	if (list_empty(keys))
		return;

	key_for_each_safe(ep_key, tmp, keys) {
		list_del_init(&ep_key->key_list);
		sctp_auth_shkey_release(ep_key);
	}
}

/* Compare two byte vectors as numbers.  Return values
 * are:
 * 	  0 - vectors are equal
 * 	< 0 - vector 1 is smaller than vector2
 * 	> 0 - vector 1 is greater than vector2
 *
 * Algorithm is:
 * 	This is performed by selecting the numerically smaller key vector...
 *	If the key vectors are equal as numbers but differ in length ...
 *	the shorter vector is considered smaller
 *
 * Examples (with small values):
 * 	000123456789 > 123456789 (first number is longer)
 * 	000123456789 < 234567891 (second number is larger numerically)
 * 	123456789 > 2345678 	 (first number is both larger & longer)
 */
static int sctp_auth_compare_vectors(struct sctp_auth_bytes *vector1,
			      struct sctp_auth_bytes *vector2)
{
	int diff;
	int i;
	const __u8 *longer;

	diff = vector1->len - vector2->len;
	if (diff) {
		longer = (diff > 0) ? vector1->data : vector2->data;

		/* Check to see if the longer number is
		 * lead-zero padded.  If it is not, it
		 * is automatically larger numerically.
		 */
		for (i = 0; i < abs(diff); i++) {
			if (longer[i] != 0)
				return diff;
		}
	}

	/* lengths are the same, compare numbers */
	return memcmp(vector1->data, vector2->data, vector1->len);
}

/*
 * Create a key vector as described in SCTP-AUTH, Section 6.1
 *    The RANDOM parameter, the CHUNKS parameter and the HMAC-ALGO
 *    parameter sent by each endpoint are concatenated as byte vectors.
 *    These parameters include the parameter type, parameter length, and
 *    the parameter value, but padding is omitted; all padding MUST be
 *    removed from this concatenation before proceeding with further
 *    computation of keys.  Parameters which were not sent are simply
 *    omitted from the concatenation process.  The resulting two vectors
 *    are called the two key vectors.
 */
static struct sctp_auth_bytes *sctp_auth_make_key_vector(
			struct sctp_random_param *random,
			struct sctp_chunks_param *chunks,
			struct sctp_hmac_algo_param *hmacs,
			gfp_t gfp)
{
	struct sctp_auth_bytes *new;
	__u32	len;
	__u32	offset = 0;
	__u16	random_len, hmacs_len, chunks_len = 0;

	random_len = ntohs(random->param_hdr.length);
	hmacs_len = ntohs(hmacs->param_hdr.length);
	if (chunks)
		chunks_len = ntohs(chunks->param_hdr.length);

	len = random_len + hmacs_len + chunks_len;

	new =