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ipv6: sr: Prepare HMAC key ahead of time 

Prepare the HMAC key when it is added to the kernel, instead of
preparing it implicitly for every packet.  This significantly improves
the performance of seg6_hmac_compute().  A microbenchmark on x86_64
shows seg6_hmac_compute() (with HMAC-SHA256) dropping from ~1978 cycles
to ~1419 cycles, a 28% improvement.

The size of 'struct seg6_hmac_info' increases by 128 bytes, but that
should be fine, since there should not be a massive number of keys.

Signed-off-by: Eric Biggers <ebiggers@kernel.org>
Link: https://patch.msgid.link/20250824013644.71928-3-ebiggers@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Eric Biggers 2025-08-23 21:36:44 -04:00 committed by Jakub Kicinski
parent 095928e7d8
commit fe60065689
2 changed files with 17 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
include/net/seg6_hmac.h
View File

@ -9,6 +9,8 @@
#ifndef _NET_SEG6_HMAC_H
#define _NET_SEG6_HMAC_H
#include <crypto/sha1.h>
#include <crypto/sha2.h>
#include <net/flow.h>
#include <net/ip6_fib.h>
#include <net/sock.h>
@ -26,9 +28,15 @@ struct seg6_hmac_info {
struct rcu_head rcu;
u32 hmackeyid;
/* The raw key, kept only so it can be returned back to userspace */
char secret[SEG6_HMAC_SECRET_LEN];
u8 slen;
u8 alg_id;
/* The prepared key, which the calculations actually use */
union {
struct hmac_sha1_key sha1;
struct hmac_sha256_key sha256;
} key;
};
extern int seg6_hmac_compute(struct seg6_hmac_info *hinfo,

14
net/ipv6/seg6_hmac.c
View File

@ -148,19 +148,18 @@ int seg6_hmac_compute(struct seg6_hmac_info *hinfo, struct ipv6_sr_hdr *hdr,
switch (hinfo->alg_id) {
case SEG6_HMAC_ALGO_SHA1:
hmac_sha1_usingrawkey(hinfo->secret, hinfo->slen, ring, plen,
output);
hmac_sha1(&hinfo->key.sha1, ring, plen, output);
static_assert(SEG6_HMAC_FIELD_LEN > SHA1_DIGEST_SIZE);
memset(&output[SHA1_DIGEST_SIZE], 0,
SEG6_HMAC_FIELD_LEN - SHA1_DIGEST_SIZE);
break;
case SEG6_HMAC_ALGO_SHA256:
hmac_sha256_usingrawkey(hinfo->secret, hinfo->slen, ring, plen,
output);
hmac_sha256(&hinfo->key.sha256, ring, plen, output);
static_assert(SEG6_HMAC_FIELD_LEN == SHA256_DIGEST_SIZE);
break;
default:
ret = -ENOENT;
WARN_ON_ONCE(1);
ret = -EINVAL;
break;
}
local_unlock_nested_bh(&hmac_storage.bh_lock);
@ -238,7 +237,12 @@ int seg6_hmac_info_add(struct net *net, u32 key, struct seg6_hmac_info *hinfo)
switch (hinfo->alg_id) {
case SEG6_HMAC_ALGO_SHA1:
hmac_sha1_preparekey(&hinfo->key.sha1,
hinfo->secret, hinfo->slen);
break;
case SEG6_HMAC_ALGO_SHA256:
hmac_sha256_preparekey(&hinfo->key.sha256,
hinfo->secret, hinfo->slen);
break;
default:
return -EINVAL;