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[SCTP]: Implement SCTP-AUTH internals

Browse source 
This patch implements the internals operations of the AUTH, such as
key computation and storage.  It also adds necessary variables to
the SCTP data structures.

Signed-off-by: Vlad Yasevich <vladislav.yasevich@hp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Vlad Yasevich 2007-10-09 01:15:59 -07:00 • committed by David S. Miller
parent f7b0e93ba1
commit 1f485649f5
7 changed files with 977 additions and 8 deletions
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745
net/sctp/auth.c Normal file
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/* SCTP kernel reference Implementation
* (C) Copyright 2007 Hewlett-Packard Development Company, L.P.
*
* This file is part of the SCTP kernel reference Implementation
*
* The SCTP reference implementation is free software;
* you can redistribute it and/or modify it under the terms of
* the GNU General Public License as published by
* the Free Software Foundation; either version 2, or (at your option)
* any later version.
*
* The SCTP reference implementation is distributed in the hope that it
* will be useful, but WITHOUT ANY WARRANTY; without even the implied
* ************************
* warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
* See the GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with GNU CC; see the file COPYING. If not, write to
* the Free Software Foundation, 59 Temple Place - Suite 330,
* Boston, MA 02111-1307, USA.
*
* Please send any bug reports or fixes you make to the
* email address(es):
* lksctp developers <lksctp-developers@lists.sourceforge.net>
*
* Or submit a bug report through the following website:
* http://www.sf.net/projects/lksctp
*
* Written or modified by:
* Vlad Yasevich <vladislav.yasevich@hp.com>
*
* Any bugs reported given to us we will try to fix... any fixes shared will
* be incorporated into the next SCTP release.
*/
#include <linux/types.h>
#include <linux/crypto.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,
},
{
.hmac_id = SCTP_AUTH_HMAC_ID_SHA256,
.hmac_name="hmac(sha256)",
.hmac_len = SCTP_SHA256_SIG_SIZE,
}
};
void sctp_auth_key_put(struct sctp_auth_bytes *key)
{
if (!key)
return;
if (atomic_dec_and_test(&key->refcnt)) {
kfree(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;
/* Allocate the shared key */
key = kmalloc(sizeof(struct sctp_auth_bytes) + key_len, gfp);
if (!key)
return NULL;
key->len = key_len;
atomic_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);
new->key_id = key_id;
return new;
}
/* Free the shared key stucture */
void sctp_auth_shkey_free(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);
}
/* Destory 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_free(ep_key);
}
}
/* Compare two byte vectors as numbers. Return values
* are:
* 0 - vectors are equal
* < 0 - vector 1 is smaller then vector2
* > 0 - vector 1 is greater then 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(
sctp_random_param_t *random,
sctp_chunks_param_t *chunks,
sctp_hmac_algo_param_t *hmacs,
gfp_t gfp)
{
struct sctp_auth_bytes *new;
__u32 len;
__u32 offset = 0;
len = ntohs(random->param_hdr.length) + ntohs(hmacs->param_hdr.length);
if (chunks)
len += ntohs(chunks->param_hdr.length);
new = kmalloc(sizeof(struct sctp_auth_bytes) + len, gfp);
if (!new)
return NULL;
new->len = len;
memcpy(new->data, random, ntohs(random->param_hdr.length));
offset += ntohs(random->param_hdr.length);
if (chunks) {
memcpy(new->data + offset, chunks,
ntohs(chunks->param_hdr.length));
offset += ntohs(chunks->param_hdr.length);
}
memcpy(new->data + offset, hmacs, ntohs(hmacs->param_hdr.length));
return new;
}
/* Make a key vector based on our local parameters */
struct sctp_auth_bytes *sctp_auth_make_local_vector(
const struct sctp_association *asoc,
gfp_t gfp)
{
return sctp_auth_make_key_vector(
(sctp_random_param_t*)asoc->c.auth_random,
(sctp_chunks_param_t*)asoc->c.auth_chunks,
(sctp_hmac_algo_param_t*)asoc->c.auth_hmacs,
gfp);
}
/* Make a key vector based on peer's parameters */
struct sctp_auth_bytes *sctp_auth_make_peer_vector(
const struct sctp_association *asoc,
gfp_t gfp)
{
return sctp_auth_make_key_vector(asoc->peer.peer_random,
asoc->peer.peer_chunks,
asoc->peer.peer_hmacs,
gfp);
}
/* Set the value of the association shared key base on the parameters
* given. The algorithm is:
* From the endpoint pair shared keys and the key vectors the
* association shared keys are computed. This is performed by selecting
* the numerically smaller key vector and concatenating it to the
* endpoint pair shared key, and then concatenating the numerically
* larger key vector to that. The result of the concatenation is the
* association shared key.
*/
static struct sctp_auth_bytes *sctp_auth_asoc_set_secret(
struct sctp_shared_key *ep_key,
struct sctp_auth_bytes *first_vector,
struct sctp_auth_bytes *last_vector,
gfp_t gfp)
{
struct sctp_auth_bytes *secret;
__u32 offset = 0;
__u32 auth_len;
auth_len = first_vector->len + last_vector->len;
if (ep_key->key)
auth_len += ep_key->key->len;
secret = sctp_auth_create_key(auth_len, gfp);
if (!secret)
return NULL;
if (ep_key->key) {
memcpy(secret->data, ep_key->key->data, ep_key->key->len);
offset += ep_key->key->len;
}
memcpy(secret->data + offset, first_vector->data, first_vector->len);
offset += first_vector->len;
memcpy(secret->data + offset, last_vector->data, last_vector->len);
return secret;
}
/* Create an association shared key. Follow the algorithm
* described in SCTP-AUTH, Section 6.1
*/
static struct sctp_auth_bytes *sctp_auth_asoc_create_secret(
const struct sctp_association *asoc,
struct sctp_shared_key *ep_key,
gfp_t gfp)
{
struct sctp_auth_bytes *local_key_vector;
struct sctp_auth_bytes *peer_key_vector;
struct sctp_auth_bytes *first_vector,
*last_vector;
struct sctp_auth_bytes *secret = NULL;
int cmp;
/* Now we need to build the key vectors
* 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.
*/
local_key_vector = sctp_auth_make_local_vector(asoc, gfp);
peer_key_vector = sctp_auth_make_peer_vector(asoc, gfp);
if (!peer_key_vector || !local_key_vector)
goto out;
/* Figure out the order in wich the key_vectors will be
* added to the endpoint shared key.
* SCTP-AUTH, Section 6.1:
* This is performed by selecting the numerically smaller key
* vector and concatenating it to the endpoint pair shared
* key, and then concatenating the numerically larger key
* vector to that. If the key vectors are equal as numbers
* but differ in length, then the concatenation order is the
* endpoint shared key, followed by the shorter key vector,
* followed by the longer key vector. Otherwise, the key
* vectors are identical, and may be concatenated to the
* endpoint pair key in any order.
*/
cmp = sctp_auth_compare_vectors(local_key_vector,
peer_key_vector);
if (cmp < 0) {
first_vector = local_key_vector;
last_vector = peer_key_vector;
} else {
first_vector = peer_key_vector;
last_vector = local_key_vector;
}
secret = sctp_auth_asoc_set_secret(ep_key, first_vector, last_vector,
gfp);
out:
kfree(local_key_vector);
kfree(peer_key_vector);
return secret;
}
/*
* Populate the association overlay list with the list
* from the endpoint.
*/
int sctp_auth_asoc_copy_shkeys(const struct sctp_endpoint *ep,
struct sctp_association *asoc,
gfp_t gfp)
{
struct sctp_shared_key *sh_key;
struct sctp_shared_key *new;
BUG_ON(!list_empty(&asoc->endpoint_shared_keys));
key_for_each(sh_key, &ep->endpoint_shared_keys) {
new = sctp_auth_shkey_create(sh_key->key_id, gfp);
if (!new)
goto nomem;
new->key = sh_key->key;
sctp_auth_key_hold(new->key);
list_add(&new->key_list, &asoc->endpoint_shared_keys);
}
return 0;
nomem:
sctp_auth_destroy_keys(&asoc->endpoint_shared_keys);
return -ENOMEM;
}
/* Public interface to creat the association shared key.
* See code above for the algorithm.
*/
int sctp_auth_asoc_init_active_key(struct sctp_association *asoc, gfp_t gfp)
{
struct sctp_auth_bytes *secret;
struct sctp_shared_key *ep_key;
/* If we don't support AUTH, or peer is not capable
* we don't need to do anything.
*/
if (!sctp_auth_enable || !asoc->peer.auth_capable)
return 0;
/* If the key_id is non-zero and we couldn't find an
* endpoint pair shared key, we can't compute the
* secret.
* For key_id 0, endpoint pair shared key is a NULL key.
*/
ep_key = sctp_auth_get_shkey(asoc, asoc->active_key_id);
BUG_ON(!ep_key);
secret = sctp_auth_asoc_create_secret(asoc, ep_key, gfp);
if (!secret)
return -ENOMEM;
sctp_auth_key_put(asoc->asoc_shared_key);
asoc->asoc_shared_key = secret;
return 0;
}
/* Find the endpoint pair shared key based on the key_id */
struct sctp_shared_key *sctp_auth_get_shkey(
const struct sctp_association *asoc,
__u16 key_id)
{
struct sctp_shared_key *key = NULL;
/* First search associations set of endpoint pair shared keys */
key_for_each(key, &asoc->endpoint_shared_keys) {
if (key->key_id == key_id)
break;
}
return key;
}
/*
* Initialize all the possible digest transforms that we can use. Right now
* now, the supported digests are SHA1 and SHA256. We do this here once
* because of the restrictiong that transforms may only be allocated in
* user context. This forces us to pre-allocated all possible transforms
* at the endpoint init time.
*/
int sctp_auth_init_hmacs(struct sctp_endpoint *ep, gfp_t gfp)
{
struct crypto_hash *tfm = NULL;
__u16 id;
/* if the transforms are already allocted, we are done */
if (!sctp_auth_enable) {
ep->auth_hmacs = NULL;
return 0;
}
if (ep->auth_hmacs)
return 0;
/* Allocated the array of pointers to transorms */
ep->auth_hmacs = kzalloc(
sizeof(struct crypto_hash *) * SCTP_AUTH_NUM_HMACS,
gfp);
if (!ep->auth_hmacs)
return -ENOMEM;
for (id = 0; id < SCTP_AUTH_NUM_HMACS; id++) {
/* See is we support the id. Supported IDs have name and
* length fields set, so that we can allocated and use
* them. We can safely just check for name, for without the
* name, we can't allocate the TFM.
*/
if (!sctp_hmac_list[id].hmac_name)
continue;
/* If this TFM has been allocated, we are all set */
if (ep->auth_hmacs[id])
continue;
/* Allocate the ID */
tfm = crypto_alloc_hash(sctp_hmac_list[id].hmac_name, 0,
CRYPTO_ALG_ASYNC);
if (IS_ERR(tfm))
goto out_err;
ep->auth_hmacs[id] = tfm;
}
return 0;
out_err:
/* Clean up any successfull allocations */
sctp_auth_destroy_hmacs(ep->auth_hmacs);
return -ENOMEM;
}
/* Destroy the hmac tfm array */
void sctp_auth_destroy_hmacs(struct crypto_hash *auth_hmacs[])
{
int i;
if (!auth_hmacs)
return;
for (i = 0; i < SCTP_AUTH_NUM_HMACS; i++)
{
if (auth_hmacs[i])
crypto_free_hash(auth_hmacs[i]);
}
kfree(auth_hmacs);
}
struct sctp_hmac *sctp_auth_get_hmac(__u16 hmac_id)
{
return &sctp_hmac_list[hmac_id];
}
/* Get an hmac description information that we can use to build
* the AUTH chunk
*/
struct sctp_hmac *sctp_auth_asoc_get_hmac(const struct sctp_association *asoc)
{
struct sctp_hmac_algo_param *hmacs;
__u16 n_elt;
__u16 id = 0;
int i;
/* If we have a default entry, use it */
if (asoc->default_hmac_id)
return &sctp_hmac_list[asoc->default_hmac_id];
/* Since we do not have a default entry, find the first entry
* we support and return that. Do not cache that id.
*/
hmacs = asoc->peer.peer_hmacs;
if (!hmacs)
return NULL;
n_elt = (ntohs(hmacs->param_hdr.length) - sizeof(sctp_paramhdr_t)) >> 1;
for (i = 0; i < n_elt; i++) {
id = ntohs(hmacs->hmac_ids[i]);
/* Check the id is in the supported range */
if (id > SCTP_AUTH_HMAC_ID_MAX)
continue;
/* See is we support the id. Supported IDs have name and
* length fields set, so that we can allocated and use
* them. We can safely just check for name, for without the
* name, we can't allocate the TFM.
*/
if (!sctp_hmac_list[id].hmac_name)
continue;
break;
}
if (id == 0)
return NULL;
return &sctp_hmac_list[id];
}
static int __sctp_auth_find_hmacid(__u16 *hmacs, int n_elts, __u16 hmac_id)
{
int found = 0;
int i;
for (i = 0; i < n_elts; i++) {
if (hmac_id == hmacs[i]) {
found = 1;
break;
}
}
return found;
}
/* See if the HMAC_ID is one that we claim as supported */
int sctp_auth_asoc_verify_hmac_id(const struct sctp_association *asoc,
__u16 hmac_id)
{
struct sctp_hmac_algo_param *hmacs;
__u16 n_elt;
if (!asoc)
return 0;
hmacs = (struct sctp_hmac_algo_param *)asoc->c.auth_hmacs;
n_elt = (ntohs(hmacs->param_hdr.length) - sizeof(sctp_paramhdr_t)) >> 1;
return __sctp_auth_find_hmacid(hmacs->hmac_ids, n_elt, hmac_id);
}
/* Cache the default HMAC id. This to follow this text from SCTP-AUTH:
* Section 6.1:
* The receiver of a HMAC-ALGO parameter SHOULD use the first listed
* algorithm it supports.
*/
void sctp_auth_asoc_set_default_hmac(struct sctp_association *asoc,
struct sctp_hmac_algo_param *hmacs)
{
struct sctp_endpoint *ep;
__u16 id;
int i;
int n_params;
/* if the default id is already set, use it */
if (asoc->default_hmac_id)
return;
n_params = (ntohs(hmacs->param_hdr.length)
- sizeof(sctp_paramhdr_t)) >> 1;
ep = asoc->ep;
for (i = 0; i < n_params; i++) {
id = ntohs(hmacs->hmac_ids[i]);
/* Check the id is in the supported range */
if (id > SCTP_AUTH_HMAC_ID_MAX)
continue;
/* If this TFM has been allocated, use this id */
if (ep->auth_hmacs[id]) {
asoc->default_hmac_id = id;
break;
}
}
}
/* Check to see if the given chunk is supposed to be authenticated */
static int __sctp_auth_cid(sctp_cid_t chunk, struct sctp_chunks_param *param)
{
unsigned short len;
int found = 0;
int i;
if (!param)
return 0;
len = ntohs(param->param_hdr.length) - sizeof(sctp_paramhdr_t);
/* SCTP-AUTH, Section 3.2
* The chunk types for INIT, INIT-ACK, SHUTDOWN-COMPLETE and AUTH
* chunks MUST NOT be listed in the CHUNKS parameter. However, if
* a CHUNKS parameter is received then the types for INIT, INIT-ACK,
* SHUTDOWN-COMPLETE and AUTH chunks MUST be ignored.
*/
for (i = 0; !found && i < len; i++) {
switch (param->chunks[i]) {
case SCTP_CID_INIT:
case SCTP_CID_INIT_ACK:
case SCTP_CID_SHUTDOWN_COMPLETE:
case SCTP_CID_AUTH:
break;
default:
if (param->chunks[i] == chunk)
found = 1;
break;
}
}
return found;
}
/* Check if peer requested that this chunk is authenticated */
int sctp_auth_send_cid(sctp_cid_t chunk, const struct sctp_association *asoc)
{
if (!sctp_auth_enable || !asoc || !asoc->peer.auth_capable)
return 0;
return __sctp_auth_cid(chunk, asoc->peer.peer_chunks);
}
/* Check if we requested that peer authenticate this chunk. */
int sctp_auth_recv_cid(sctp_cid_t chunk, const struct sctp_association *asoc)
{
if (!sctp_auth_enable || !asoc)
return 0;
return __sctp_auth_cid(chunk,
(struct sctp_chunks_param *)asoc->c.auth_chunks);
}
/* SCTP-AUTH: Section 6.2:
* The sender MUST calculate the MAC as described in RFC2104 [2] using
* the hash function H as described by the MAC Identifier and the shared
* association key K based on the endpoint pair shared key described by
* the shared key identifier. The 'data' used for the computation of
* the AUTH-chunk is given by the AUTH chunk with its HMAC field set to
* zero (as shown in Figure 6) followed by all chunks that are placed
* after the AUTH chunk in the SCTP packet.
*/
void sctp_auth_calculate_hmac(const struct sctp_association *asoc,
struct sk_buff *skb,
struct sctp_auth_chunk *auth,
gfp_t gfp)
{
struct scatterlist sg;
struct hash_desc desc;
struct sctp_auth_bytes *asoc_key;
__u16 key_id, hmac_id;
__u8 *digest;
unsigned char *end;
int free_key = 0;
/* Extract the info we need:
* - hmac id
* - key id
*/
key_id = ntohs(auth->auth_hdr.shkey_id);
hmac_id = ntohs(auth->auth_hdr.hmac_id);
if (key_id == asoc->active_key_id)
asoc_key = asoc->asoc_shared_key;
else {
struct sctp_shared_key *ep_key;
ep_key = sctp_auth_get_shkey(asoc, key_id);
if (!ep_key)
return;
asoc_key = sctp_auth_asoc_create_secret(asoc, ep_key, gfp);
if (!asoc_key)
return;
free_key = 1;
}
/* set up scatter list */
end = skb_tail_pointer(skb);
sg.page = virt_to_page(auth);
sg.offset = (unsigned long)(auth) % PAGE_SIZE;
sg.length = end - (unsigned char *)auth;
desc.tfm = asoc->ep->auth_hmacs[hmac_id];
desc.flags = 0;
digest = auth->auth_hdr.hmac;
if (crypto_hash_setkey(desc.tfm, &asoc_key->data[0], asoc_key->len))
goto free;
crypto_hash_digest(&desc, &sg, sg.length, digest);
free:
if (free_key)
sctp_auth_key_put(asoc_key);
}