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MEDIUM: quic: optimize HKDF operations by reusing per-thread contexts

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Allocating and freeing an OpenSSL EVP_PKEY_CTX context via
EVP_PKEY_CTX_new_id() and EVP_PKEY_CTX_free() on every HKDF cryptographic
operation (such as during stateless reset token generation) induces
unnecessary memory allocation overhead.

Optimize this by introducing a global per-thread context array
'quic_tls_hkdf_ctxs'. These contexts are allocated and initialized once
at startup via a POST_CHECK hook (quic_tls_alloc_hkdf_ctxs) and are
properly freed at exit via a POST_DEINIT hook (quic_tls_dealloc_hkdf_ctxs).

The functions quic_hkdf_extract(), quic_hkdf_expand(), and
quic_hkdf_extract_and_expand() now reuse the pre-allocated context
corresponding to the current thread ID ('tid'), removing dynamic
allocations from these frequent execution paths.

As a cleanup, quic_hkdf_expand() is now static and unexported from the
header file.

Should be easily backported to all versions for optimization purposes.
This commit is contained in:
Frederic Lecaille 2026-05-28 14:49:07 +02:00
parent 52ce316786
commit 4e0af590e8
2 changed files with 59 additions and 46 deletions
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5
include/haproxy/quic_tls.h
View file

@ -97,11 +97,6 @@ int quic_tls_derive_token_secret(const EVP_MD *md,
const unsigned char *salt, size_t saltlen,
const unsigned char *secret, size_t secretlen);
int quic_hkdf_expand(const EVP_MD *md,
unsigned char *buf, size_t buflen,
const unsigned char *key, size_t keylen,
const unsigned char *label, size_t labellen);
int quic_hkdf_expand_label(const EVP_MD *md,
unsigned char *buf, size_t buflen,
const unsigned char *key, size_t keylen,

100
src/quic_tls.c
View file

@ -6,6 +6,7 @@
#include <openssl/kdf.h>
#include <openssl/ssl.h>
#include <haproxy/errors.h>
#include <haproxy/buf.h>
#include <haproxy/chunk.h>
#include <haproxy/pool.h>
@ -25,6 +26,8 @@ DECLARE_POOL(pool_head_quic_tls_key, "quic_tls_key", QUIC_TLS_KEY_LEN);
DECLARE_TYPED_POOL(pool_head_quic_crypto_buf, "quic_crypto_buf", struct quic_crypto_buf);
DECLARE_STATIC_TYPED_POOL(pool_head_quic_cstream, "quic_cstream", struct quic_cstream);
EVP_PKEY_CTX **quic_tls_hkdf_ctxs;
/* Initial salt depending on QUIC version to derive client/server initial secrets.
* This one is for draft-29 QUIC version.
*/
@ -314,16 +317,12 @@ void qc_enc_level_free(struct quic_conn *qc, struct quic_enc_level **qel)
*qel = NULL;
}
int quic_hkdf_extract(const EVP_MD *md,
unsigned char *buf, size_t buflen,
const unsigned char *key, size_t keylen,
const unsigned char *salt, size_t saltlen)
static int quic_hkdf_extract(const EVP_MD *md,
unsigned char *buf, size_t buflen,
const unsigned char *key, size_t keylen,
const unsigned char *salt, size_t saltlen)
{
EVP_PKEY_CTX *ctx;
ctx = EVP_PKEY_CTX_new_id(EVP_PKEY_HKDF, NULL);
if (!ctx)
return 0;
EVP_PKEY_CTX *ctx = quic_tls_hkdf_ctxs[tid];
if (EVP_PKEY_derive_init(ctx) <= 0 ||
EVP_PKEY_CTX_hkdf_mode(ctx, EVP_PKEY_HKDEF_MODE_EXTRACT_ONLY) <= 0 ||
@ -331,26 +330,17 @@ int quic_hkdf_extract(const EVP_MD *md,
EVP_PKEY_CTX_set1_hkdf_salt(ctx, salt, saltlen) <= 0 ||
EVP_PKEY_CTX_set1_hkdf_key(ctx, key, keylen) <= 0 ||
EVP_PKEY_derive(ctx, buf, &buflen) <= 0)
goto err;
return 0;
EVP_PKEY_CTX_free(ctx);
return 1;
err:
EVP_PKEY_CTX_free(ctx);
return 0;
}
int quic_hkdf_expand(const EVP_MD *md,
unsigned char *buf, size_t buflen,
const unsigned char *key, size_t keylen,
const unsigned char *label, size_t labellen)
static int quic_hkdf_expand(const EVP_MD *md,
unsigned char *buf, size_t buflen,
const unsigned char *key, size_t keylen,
const unsigned char *label, size_t labellen)
{
EVP_PKEY_CTX *ctx;
ctx = EVP_PKEY_CTX_new_id(EVP_PKEY_HKDF, NULL);
if (!ctx)
return 0;
EVP_PKEY_CTX *ctx = quic_tls_hkdf_ctxs[tid];
if (EVP_PKEY_derive_init(ctx) <= 0 ||
EVP_PKEY_CTX_hkdf_mode(ctx, EVP_PKEY_HKDEF_MODE_EXPAND_ONLY) <= 0 ||
@ -358,14 +348,9 @@ int quic_hkdf_expand(const EVP_MD *md,
EVP_PKEY_CTX_set1_hkdf_key(ctx, key, keylen) <= 0 ||
EVP_PKEY_CTX_add1_hkdf_info(ctx, label, labellen) <= 0 ||
EVP_PKEY_derive(ctx, buf, &buflen) <= 0)
goto err;
return 0;
EVP_PKEY_CTX_free(ctx);
return 1;
err:
EVP_PKEY_CTX_free(ctx);
return 0;
}
/* Extracts a peudo-random secret key from <key> which is eventually not
@ -382,11 +367,7 @@ int quic_hkdf_extract_and_expand(const EVP_MD *md,
const unsigned char *salt, size_t saltlen,
const unsigned char *label, size_t labellen)
{
EVP_PKEY_CTX *ctx;
ctx = EVP_PKEY_CTX_new_id(EVP_PKEY_HKDF, NULL);
if (!ctx)
return 0;
EVP_PKEY_CTX *ctx = quic_tls_hkdf_ctxs[tid];
if (EVP_PKEY_derive_init(ctx) <= 0 ||
EVP_PKEY_CTX_hkdf_mode(ctx, EVP_PKEY_HKDEF_MODE_EXTRACT_AND_EXPAND) <= 0 ||
@ -395,14 +376,9 @@ int quic_hkdf_extract_and_expand(const EVP_MD *md,
EVP_PKEY_CTX_set1_hkdf_key(ctx, key, keylen) <= 0 ||
EVP_PKEY_CTX_add1_hkdf_info(ctx, label, labellen) <= 0 ||
EVP_PKEY_derive(ctx, buf, &buflen) <= 0)
goto err;
return 0;
EVP_PKEY_CTX_free(ctx);
return 1;
err:
EVP_PKEY_CTX_free(ctx);
return 0;
}
/* https://quicwg.org/base-drafts/draft-ietf-quic-tls.html#protection-keys
@ -1240,3 +1216,45 @@ int quic_tls_finalize(struct quic_conn *qc, int server)
quic_tls_ctx_free(&qc->nictx);
goto out;
}
/* Cryptographic context allocator for HKDF operations */
static int quic_tls_dealloc_hkdf_ctxs(void)
{
int i;
if (!quic_tls_hkdf_ctxs)
return 1;
for (i = 0; i < global.nbthread; i++)
EVP_PKEY_CTX_free(quic_tls_hkdf_ctxs[i]);
free(quic_tls_hkdf_ctxs);
return 1;
}
REGISTER_POST_DEINIT(quic_tls_dealloc_hkdf_ctxs);
/* Cryptographic context for HKDF operations deallocator*/
static int quic_tls_alloc_hkdf_ctxs(void)
{
int i, ret = -1;
quic_tls_hkdf_ctxs = calloc(global.nbthread, sizeof(*quic_tls_hkdf_ctxs));
if (!quic_tls_hkdf_ctxs)
goto err;
for (i = 0; i < global.nbthread; i++) {
quic_tls_hkdf_ctxs[i] = EVP_PKEY_CTX_new_id(EVP_PKEY_HKDF, NULL);
if (!quic_tls_hkdf_ctxs[i])
goto err;
}
ret = 0;
leave:
return ret;
err:
ha_alert("failed to alloc the QUIC HKDF contexts.\n");
quic_tls_dealloc_hkdf_ctxs();
goto leave;
}
REGISTER_POST_CHECK(quic_tls_alloc_hkdf_ctxs);