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QUIC: use AEAD to encrypt address validation tokens.

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Previously used AES256-CBC is now substituted with AES256-GCM.  Although there
seem to be no tangible consequences of token integrity loss.
This commit is contained in:
Roman Arutyunyan 2023-06-08 14:58:01 +04:00
parent b051754d9d
commit 6bdfd58f26
2 changed files with 36 additions and 17 deletions
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44
src/event/quic/ngx_event_quic_tokens.c
View File

@ -69,11 +69,10 @@ ngx_quic_new_token(ngx_log_t *log, struct sockaddr *sockaddr,
len = p - in; len = p - in;
cipher = EVP_aes_256_cbc(); cipher = EVP_aes_256_gcm();
iv_len = NGX_QUIC_AES_256_CBC_IV_LEN; iv_len = NGX_QUIC_AES_256_GCM_IV_LEN;
if ((size_t) (iv_len + len + NGX_QUIC_AES_256_CBC_BLOCK_SIZE) > token->len) if ((size_t) (iv_len + len + NGX_QUIC_AES_256_GCM_TAG_LEN) > token->len) {
{
ngx_log_error(NGX_LOG_ALERT, log, 0, "quic token buffer is too small"); ngx_log_error(NGX_LOG_ALERT, log, 0, "quic token buffer is too small");
return NGX_ERROR; return NGX_ERROR;
} }
@ -108,6 +107,17 @@ ngx_quic_new_token(ngx_log_t *log, struct sockaddr *sockaddr,
token->len += len; token->len += len;
if (EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_GET_TAG,
NGX_QUIC_AES_256_GCM_TAG_LEN,
token->data + token->len)
== 0)
{
EVP_CIPHER_CTX_free(ctx);
return NGX_ERROR;
}
token->len += NGX_QUIC_AES_256_GCM_TAG_LEN;
EVP_CIPHER_CTX_free(ctx); EVP_CIPHER_CTX_free(ctx);
#ifdef NGX_QUIC_DEBUG_PACKETS #ifdef NGX_QUIC_DEBUG_PACKETS
@ -184,17 +194,19 @@ ngx_quic_validate_token(ngx_connection_t *c, u_char *key,
/* Retry token or NEW_TOKEN in a previous connection */ /* Retry token or NEW_TOKEN in a previous connection */
cipher = EVP_aes_256_cbc(); cipher = EVP_aes_256_gcm();
iv = pkt->token.data; iv = pkt->token.data;
iv_len = NGX_QUIC_AES_256_CBC_IV_LEN; iv_len = NGX_QUIC_AES_256_GCM_IV_LEN;
/* sanity checks */ /* sanity checks */
if (pkt->token.len < (size_t) iv_len + NGX_QUIC_AES_256_CBC_BLOCK_SIZE) { if (pkt->token.len < (size_t) iv_len + NGX_QUIC_AES_256_GCM_TAG_LEN) {
goto garbage; goto garbage;
} }
if (pkt->token.len > (size_t) iv_len + NGX_QUIC_MAX_TOKEN_SIZE) { if (pkt->token.len > (size_t) iv_len + NGX_QUIC_MAX_TOKEN_SIZE
+ NGX_QUIC_AES_256_GCM_TAG_LEN)
{
goto garbage; goto garbage;
} }
@ -209,15 +221,23 @@ ngx_quic_validate_token(ngx_connection_t *c, u_char *key,
} }
p = pkt->token.data + iv_len; p = pkt->token.data + iv_len;
len = pkt->token.len - iv_len; len = pkt->token.len - iv_len - NGX_QUIC_AES_256_GCM_TAG_LEN;
if (EVP_DecryptUpdate(ctx, tdec, &len, p, len) != 1) { if (EVP_DecryptUpdate(ctx, tdec, &tlen, p, len) != 1) {
EVP_CIPHER_CTX_free(ctx); EVP_CIPHER_CTX_free(ctx);
goto garbage; goto garbage;
} }
total = len; total = tlen;
if (EVP_DecryptFinal_ex(ctx, tdec + len, &tlen) <= 0) { if (EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_TAG,
NGX_QUIC_AES_256_GCM_TAG_LEN, p + len)
== 0)
{
EVP_CIPHER_CTX_free(ctx);
goto garbage;
}
if (EVP_DecryptFinal_ex(ctx, tdec + tlen, &tlen) <= 0) {
EVP_CIPHER_CTX_free(ctx); EVP_CIPHER_CTX_free(ctx);
goto garbage; goto garbage;
} }

9
src/event/quic/ngx_event_quic_tokens.h
View File

@ -15,13 +15,12 @@
#define NGX_QUIC_MAX_TOKEN_SIZE 64 #define NGX_QUIC_MAX_TOKEN_SIZE 64
/* SHA-1(addr)=20 + sizeof(time_t) + retry(1) + odcid.len(1) + odcid */ /* SHA-1(addr)=20 + sizeof(time_t) + retry(1) + odcid.len(1) + odcid */
/* RFC 3602, 2.1 and 2.4 for AES-CBC block size and IV length */ #define NGX_QUIC_AES_256_GCM_IV_LEN 12
#define NGX_QUIC_AES_256_CBC_IV_LEN 16 #define NGX_QUIC_AES_256_GCM_TAG_LEN 16
#define NGX_QUIC_AES_256_CBC_BLOCK_SIZE 16
#define NGX_QUIC_TOKEN_BUF_SIZE (NGX_QUIC_AES_256_CBC_IV_LEN \ #define NGX_QUIC_TOKEN_BUF_SIZE (NGX_QUIC_AES_256_GCM_IV_LEN \
+ NGX_QUIC_MAX_TOKEN_SIZE \ + NGX_QUIC_MAX_TOKEN_SIZE \
+ NGX_QUIC_AES_256_CBC_BLOCK_SIZE) + NGX_QUIC_AES_256_GCM_TAG_LEN)
ngx_int_t ngx_quic_new_sr_token(ngx_connection_t *c, ngx_str_t *cid, ngx_int_t ngx_quic_new_sr_token(ngx_connection_t *c, ngx_str_t *cid,