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sctp: Use HMAC-SHA1 and HMAC-SHA256 library for chunk authentication 

For SCTP chunk authentication, use the HMAC-SHA1 and HMAC-SHA256 library
functions instead of crypto_shash.  This is simpler and faster.  There's
no longer any need to pre-allocate 'crypto_shash' objects; the SCTP code
now simply calls into the HMAC code directly.

As part of this, make SCTP always support both HMAC-SHA1 and
HMAC-SHA256.  Previously, it only guaranteed support for HMAC-SHA1.
However, HMAC-SHA256 tended to be supported too anyway, as it was
supported if CONFIG_CRYPTO_SHA256 was enabled elsewhere in the kconfig.

Acked-by: Xin Long <lucien.xin@gmail.com>
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
Link: https://patch.msgid.link/20250818205426.30222-4-ebiggers@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Eric Biggers 2025-08-18 13:54:24 -07:00 committed by Jakub Kicinski
parent dd91c79e4f
commit bf40785fa4
9 changed files with 48 additions and 177 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

17
include/net/sctp/auth.h
View File

@ -22,16 +22,11 @@ struct sctp_endpoint;
struct sctp_association;
struct sctp_authkey;
struct sctp_hmacalgo;
struct crypto_shash;
/*
* Define a generic struct that will hold all the info
* necessary for an HMAC transform
*/
/* Defines an HMAC algorithm supported by SCTP chunk authentication */
struct sctp_hmac {
__u16 hmac_id; /* one of the above ids */
char *hmac_name; /* name for loading */
__u16 hmac_len; /* length of the signature */
__u16 hmac_id; /* one of SCTP_AUTH_HMAC_ID_* */
__u16 hmac_len; /* length of the HMAC value in bytes */
};
/* This is generic structure that containst authentication bytes used
@ -78,9 +73,9 @@ int sctp_auth_asoc_copy_shkeys(const struct sctp_endpoint *ep,
struct sctp_association *asoc,
gfp_t gfp);
int sctp_auth_init_hmacs(struct sctp_endpoint *ep, gfp_t gfp);
void sctp_auth_destroy_hmacs(struct crypto_shash *auth_hmacs[]);
struct sctp_hmac *sctp_auth_get_hmac(__u16 hmac_id);
struct sctp_hmac *sctp_auth_asoc_get_hmac(const struct sctp_association *asoc);
const struct sctp_hmac *sctp_auth_get_hmac(__u16 hmac_id);
const struct sctp_hmac *
sctp_auth_asoc_get_hmac(const struct sctp_association *asoc);
void sctp_auth_asoc_set_default_hmac(struct sctp_association *asoc,
struct sctp_hmac_algo_param *hmacs);
int sctp_auth_asoc_verify_hmac_id(const struct sctp_association *asoc,

4
include/net/sctp/constants.h
View File

@ -417,16 +417,12 @@ enum {
SCTP_AUTH_HMAC_ID_RESERVED_0,
SCTP_AUTH_HMAC_ID_SHA1,
SCTP_AUTH_HMAC_ID_RESERVED_2,
#if defined (CONFIG_CRYPTO_SHA256) || defined (CONFIG_CRYPTO_SHA256_MODULE)
SCTP_AUTH_HMAC_ID_SHA256,
#endif
__SCTP_AUTH_HMAC_MAX
};
#define SCTP_AUTH_HMAC_ID_MAX __SCTP_AUTH_HMAC_MAX - 1
#define SCTP_AUTH_NUM_HMACS __SCTP_AUTH_HMAC_MAX
#define SCTP_SHA1_SIG_SIZE 20
#define SCTP_SHA256_SIG_SIZE 32
/* SCTP-AUTH, Section 3.2
* The chunk types for INIT, INIT-ACK, SHUTDOWN-COMPLETE and AUTH chunks

5
include/net/sctp/structs.h
View File

@ -1329,11 +1329,6 @@ struct sctp_endpoint {
/* rcvbuf acct. policy. */
__u32 rcvbuf_policy;
/* SCTP AUTH: array of the HMACs that will be allocated
* we need this per association so that we don't serialize
*/
struct crypto_shash **auth_hmacs;
/* SCTP-AUTH: hmacs for the endpoint encoded into parameter */
struct sctp_hmac_algo_param *auth_hmacs_list;

16
net/sctp/Kconfig
View File

@ -7,9 +7,9 @@ menuconfig IP_SCTP
tristate "The SCTP Protocol"
depends on INET
depends on IPV6 || IPV6=n
select CRYPTO
select CRYPTO_HMAC
select CRYPTO_SHA1
select CRYPTO_LIB_SHA1
select CRYPTO_LIB_SHA256
select CRYPTO_LIB_UTILS
select NET_CRC32C
select NET_UDP_TUNNEL
help
@ -79,15 +79,17 @@ config SCTP_COOKIE_HMAC_MD5
bool "Enable optional MD5 hmac cookie generation"
help
Enable optional MD5 hmac based SCTP cookie generation
select CRYPTO_HMAC if SCTP_COOKIE_HMAC_MD5
select CRYPTO_MD5 if SCTP_COOKIE_HMAC_MD5
select CRYPTO
select CRYPTO_HMAC
select CRYPTO_MD5
config SCTP_COOKIE_HMAC_SHA1
bool "Enable optional SHA1 hmac cookie generation"
help
Enable optional SHA1 hmac based SCTP cookie generation
select CRYPTO_HMAC if SCTP_COOKIE_HMAC_SHA1
select CRYPTO_SHA1 if SCTP_COOKIE_HMAC_SHA1
select CRYPTO
select CRYPTO_HMAC
select CRYPTO_SHA1
config INET_SCTP_DIAG
depends on INET_DIAG

166
net/sctp/auth.c
View File

@ -12,36 +12,37 @@
* Vlad Yasevich <vladislav.yasevich@hp.com>
*/
#include <crypto/hash.h>
#include <crypto/sha1.h>
#include <crypto/sha2.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] = {
static const 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,
.hmac_len = SHA1_DIGEST_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,
.hmac_len = SHA256_DIGEST_SIZE,
}
#endif
};
static bool sctp_hmac_supported(__u16 hmac_id)
{
return hmac_id < ARRAY_SIZE(sctp_hmac_list) &&
sctp_hmac_list[hmac_id].hmac_len != 0;
}
void sctp_auth_key_put(struct sctp_auth_bytes *key)
{
@ -444,76 +445,7 @@ struct sctp_shared_key *sctp_auth_get_shkey(
return NULL;
}
/*
* Initialize all the possible digest transforms that we can use. Right
* 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_shash *tfm = NULL;
__u16 id;
/* If the transforms are already allocated, we are done */
if (ep->auth_hmacs)
return 0;
/* Allocated the array of pointers to transorms */
ep->auth_hmacs = kcalloc(SCTP_AUTH_NUM_HMACS,
sizeof(struct crypto_shash *),
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_shash(sctp_hmac_list[id].hmac_name, 0, 0);
if (IS_ERR(tfm))
goto out_err;
ep->auth_hmacs[id] = tfm;
}
return 0;
out_err:
/* Clean up any successful allocations */
sctp_auth_destroy_hmacs(ep->auth_hmacs);
ep->auth_hmacs = NULL;
return -ENOMEM;
}
/* Destroy the hmac tfm array */
void sctp_auth_destroy_hmacs(struct crypto_shash *auth_hmacs[])
{
int i;
if (!auth_hmacs)
return;
for (i = 0; i < SCTP_AUTH_NUM_HMACS; i++) {
crypto_free_shash(auth_hmacs[i]);
}
kfree(auth_hmacs);
}
struct sctp_hmac *sctp_auth_get_hmac(__u16 hmac_id)
const struct sctp_hmac *sctp_auth_get_hmac(__u16 hmac_id)
{
return &sctp_hmac_list[hmac_id];
}
@ -521,7 +453,8 @@ struct sctp_hmac *sctp_auth_get_hmac(__u16 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)
const struct sctp_hmac *
sctp_auth_asoc_get_hmac(const struct sctp_association *asoc)
{
struct sctp_hmac_algo_param *hmacs;
__u16 n_elt;
@ -543,26 +476,10 @@ struct sctp_hmac *sctp_auth_asoc_get_hmac(const struct sctp_association *asoc)
sizeof(struct sctp_paramhdr)) >> 1;
for (i = 0; i < n_elt; i++) {
id = ntohs(hmacs->hmac_ids[i]);
/* Check the id is in the supported range. And
* see if we support the id. Supported IDs have name and
* length fields set, so that we can allocate and use
* them. We can safely just check for name, for without the
* name, we can't allocate the TFM.
*/
if (id > SCTP_AUTH_HMAC_ID_MAX ||
!sctp_hmac_list[id].hmac_name) {
id = 0;
continue;
}
break;
}
if (id == 0)
return NULL;
if (sctp_hmac_supported(id))
return &sctp_hmac_list[id];
}
return NULL;
}
static int __sctp_auth_find_hmacid(__be16 *hmacs, int n_elts, __be16 hmac_id)
@ -606,7 +523,6 @@ int sctp_auth_asoc_verify_hmac_id(const struct sctp_association *asoc,
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;
@ -617,16 +533,9 @@ void sctp_auth_asoc_set_default_hmac(struct sctp_association *asoc,
n_params = (ntohs(hmacs->param_hdr.length) -
sizeof(struct sctp_paramhdr)) >> 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]) {
if (sctp_hmac_supported(id)) {
asoc->default_hmac_id = id;
break;
}
@ -709,10 +618,9 @@ void sctp_auth_calculate_hmac(const struct sctp_association *asoc,
struct sctp_shared_key *ep_key, gfp_t gfp)
{
struct sctp_auth_bytes *asoc_key;
struct crypto_shash *tfm;
__u16 key_id, hmac_id;
unsigned char *end;
int free_key = 0;
size_t data_len;
__u8 *digest;
/* Extract the info we need:
@ -733,19 +641,17 @@ void sctp_auth_calculate_hmac(const struct sctp_association *asoc,
free_key = 1;
}
/* set up scatter list */
end = skb_tail_pointer(skb);
tfm = asoc->ep->auth_hmacs[hmac_id];
data_len = skb_tail_pointer(skb) - (unsigned char *)auth;
digest = (u8 *)(&auth->auth_hdr + 1);
if (crypto_shash_setkey(tfm, &asoc_key->data[0], asoc_key->len))
goto free;
if (hmac_id == SCTP_AUTH_HMAC_ID_SHA1) {
hmac_sha1_usingrawkey(asoc_key->data, asoc_key->len,
(const u8 *)auth, data_len, digest);
} else {
WARN_ON_ONCE(hmac_id != SCTP_AUTH_HMAC_ID_SHA256);
hmac_sha256_usingrawkey(asoc_key->data, asoc_key->len,
(const u8 *)auth, data_len, digest);
}
crypto_shash_tfm_digest(tfm, (u8 *)auth, end - (unsigned char *)auth,
digest);
free:
if (free_key)
sctp_auth_key_put(asoc_key);
}
@ -788,14 +694,11 @@ int sctp_auth_ep_set_hmacs(struct sctp_endpoint *ep,
for (i = 0; i < hmacs->shmac_num_idents; i++) {
id = hmacs->shmac_idents[i];
if (id > SCTP_AUTH_HMAC_ID_MAX)
if (!sctp_hmac_supported(id))
return -EOPNOTSUPP;
if (SCTP_AUTH_HMAC_ID_SHA1 == id)
has_sha1 = 1;
if (!sctp_hmac_list[id].hmac_name)
return -EOPNOTSUPP;
}
if (!has_sha1)
@ -1021,8 +924,6 @@ int sctp_auth_deact_key_id(struct sctp_endpoint *ep,
int sctp_auth_init(struct sctp_endpoint *ep, gfp_t gfp)
{
int err = -ENOMEM;
/* Allocate space for HMACS and CHUNKS authentication
* variables. There are arrays that we encode directly
* into parameters to make the rest of the operations easier.
@ -1060,13 +961,6 @@ int sctp_auth_init(struct sctp_endpoint *ep, gfp_t gfp)
ep->auth_chunk_list = auth_chunks;
}
/* Allocate and initialize transorms arrays for supported
* HMACs.
*/
err = sctp_auth_init_hmacs(ep, gfp);
if (err)
goto nomem;
return 0;
nomem:
@ -1075,7 +969,7 @@ int sctp_auth_init(struct sctp_endpoint *ep, gfp_t gfp)
kfree(ep->auth_chunk_list);
ep->auth_hmacs_list = NULL;
ep->auth_chunk_list = NULL;
return err;
return -ENOMEM;
}
void sctp_auth_free(struct sctp_endpoint *ep)
@ -1084,6 +978,4 @@ void sctp_auth_free(struct sctp_endpoint *ep)
kfree(ep->auth_chunk_list);
ep->auth_hmacs_list = NULL;
ep->auth_chunk_list = NULL;
sctp_auth_destroy_hmacs(ep->auth_hmacs);
ep->auth_hmacs = NULL;
}

3
net/sctp/chunk.c
View File

@ -184,7 +184,8 @@ struct sctp_datamsg *sctp_datamsg_from_user(struct sctp_association *asoc,
* DATA.
*/
if (sctp_auth_send_cid(SCTP_CID_DATA, asoc)) {
struct sctp_hmac *hmac_desc = sctp_auth_asoc_get_hmac(asoc);
const struct sctp_hmac *hmac_desc =
sctp_auth_asoc_get_hmac(asoc);
if (hmac_desc)
max_data -= SCTP_PAD4(sizeof(struct sctp_auth_chunk) +

2
net/sctp/sm_make_chunk.c
View File

@ -1320,7 +1320,7 @@ struct sctp_chunk *sctp_make_auth(const struct sctp_association *asoc,
__u16 key_id)
{
struct sctp_authhdr auth_hdr;
struct sctp_hmac *hmac_desc;
const struct sctp_hmac *hmac_desc;
struct sctp_chunk *retval;
/* Get the first hmac that the peer told us to use */

2
net/sctp/sm_statefuns.c
View File

@ -4362,7 +4362,7 @@ static enum sctp_ierror sctp_sf_authenticate(
struct sctp_shared_key *sh_key = NULL;
struct sctp_authhdr *auth_hdr;
__u8 *save_digest, *digest;
struct sctp_hmac *hmac;
const struct sctp_hmac *hmac;
unsigned int sig_len;
__u16 key_id;

10
net/sctp/socket.c
View File

@ -9581,16 +9581,6 @@ static int sctp_sock_migrate(struct sock *oldsk, struct sock *newsk,
if (err)
return err;
/* New ep's auth_hmacs should be set if old ep's is set, in case
* that net->sctp.auth_enable has been changed to 0 by users and
* new ep's auth_hmacs couldn't be set in sctp_endpoint_init().
*/
if (oldsp->ep->auth_hmacs) {
err = sctp_auth_init_hmacs(newsp->ep, GFP_KERNEL);
if (err)
return err;
}
sctp_auto_asconf_init(newsp);
/* Move any messages in the old socket's receive queue that are for the