Merge branch 'sctp-convert-to-use-crypto-lib-and-upgrade-cookie-auth'

Eric Biggers says:

====================
sctp: Convert to use crypto lib, and upgrade cookie auth

This series converts SCTP chunk and cookie authentication to use the
crypto library API instead of crypto_shash.  This is much simpler (the
diffstat should speak for itself), and also faster too.  In addition,
this series upgrades the cookie authentication to use HMAC-SHA256.

I've tested that kernels with this series applied can continue to
communicate using SCTP with older ones, in either direction, using any
choice of None, HMAC-SHA1, or HMAC-SHA256 chunk authentication.
====================

Link: https://patch.msgid.link/20250818205426.30222-1-ebiggers@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

4 files changed, 17 insertions, 48 deletions

diff --git a/include/net/netns/sctp.h b/include/net/netns/sctp.h
index d25cd7a9c5ff..c0f97f36389e 100644
--- a/include/net/netns/sctp.h
+++ b/include/net/netns/sctp.h
@@ -75,8 +75,8 @@ struct netns_sctp {
 	/* Whether Cookie Preservative is enabled(1) or not(0) */
 	int cookie_preserve_enable;
 
-	/* The namespace default hmac alg */
-	char *sctp_hmac_alg;
+	/* Whether cookie authentication is enabled(1) or not(0) */
+	int cookie_auth_enable;
 
 	/* Valid.Cookie.Life	    - 60  seconds  */
 	unsigned int valid_cookie_life;
diff --git a/include/net/sctp/auth.h b/include/net/sctp/auth.h
index d4b3b2dcd15b..3d5879e08e78 100644
--- a/include/net/sctp/auth.h
+++ b/include/net/sctp/auth.h
@@ -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,
diff --git a/include/net/sctp/constants.h b/include/net/sctp/constants.h
index 5859e0a16a58..ae3376ba0b99 100644
--- a/include/net/sctp/constants.h
+++ b/include/net/sctp/constants.h
@@ -296,9 +296,8 @@ enum { SCTP_MAX_GABS = 16 };
 					 */
 #define SCTP_DEFAULT_MINSEGMENT 512	/* MTU size ... if no mtu disc */
 
-#define SCTP_SECRET_SIZE 32		/* Number of octets in a 256 bits. */
-
-#define SCTP_SIGNATURE_SIZE 20	        /* size of a SLA-1 signature */
+#define SCTP_COOKIE_KEY_SIZE 32	/* size of cookie HMAC key */
+#define SCTP_COOKIE_MAC_SIZE 32	/* size of HMAC field in cookies */
 
 #define SCTP_COOKIE_MULTIPLE 32 /* Pad out our cookie to make our hash
 				 * functions simpler to write.
@@ -417,16 +416,12 @@ 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
diff --git a/include/net/sctp/structs.h b/include/net/sctp/structs.h
index 8a540ad9b509..2ae390219efd 100644
--- a/include/net/sctp/structs.h
+++ b/include/net/sctp/structs.h
@@ -32,6 +32,7 @@
 #ifndef __sctp_structs_h__
 #define __sctp_structs_h__
 
+#include <crypto/sha2.h>
 #include <linux/ktime.h>
 #include <linux/generic-radix-tree.h>
 #include <linux/rhashtable-types.h>
@@ -68,7 +69,6 @@ struct sctp_outq;
 struct sctp_bind_addr;
 struct sctp_ulpq;
 struct sctp_ep_common;
-struct crypto_shash;
 struct sctp_stream;
 
 
@@ -155,10 +155,6 @@ struct sctp_sock {
 	/* PF_ family specific functions.  */
 	struct sctp_pf *pf;
 
-	/* Access to HMAC transform. */
-	struct crypto_shash *hmac;
-	char *sctp_hmac_alg;
-
 	/* What is our base endpointer? */
 	struct sctp_endpoint *ep;
 
@@ -227,7 +223,8 @@ struct sctp_sock {
 		frag_interleave:1,
 		recvrcvinfo:1,
 		recvnxtinfo:1,
-		data_ready_signalled:1;
+		data_ready_signalled:1,
+		cookie_auth_enable:1;
 
 	atomic_t pd_mode;
 
@@ -335,7 +332,7 @@ struct sctp_cookie {
 
 /* The format of our cookie that we send to our peer. */
 struct sctp_signed_cookie {
-	__u8 signature[SCTP_SECRET_SIZE];
+	__u8 mac[SCTP_COOKIE_MAC_SIZE];
 	__u32 __pad;		/* force sctp_cookie alignment to 64 bits */
 	struct sctp_cookie c;
 } __packed;
@@ -1307,33 +1304,15 @@ struct sctp_endpoint {
 	/* This is really a list of struct sctp_association entries. */
 	struct list_head asocs;
 
-	/* Secret Key: A secret key used by this endpoint to compute
-	 *	      the MAC.	This SHOULD be a cryptographic quality
-	 *	      random number with a sufficient length.
-	 *	      Discussion in [RFC1750] can be helpful in
-	 *	      selection of the key.
-	 */
-	__u8 secret_key[SCTP_SECRET_SIZE];
-
- 	/* digest:  This is a digest of the sctp cookie.  This field is
- 	 * 	    only used on the receive path when we try to validate
- 	 * 	    that the cookie has not been tampered with.  We put
- 	 * 	    this here so we pre-allocate this once and can re-use
- 	 * 	    on every receive.
- 	 */
- 	__u8 *digest;
- 
+	/* Cookie authentication key used by this endpoint */
+	struct hmac_sha256_key cookie_auth_key;
+
 	/* sendbuf acct. policy.	*/
 	__u32 sndbuf_policy;
 
 	/* 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;