63 lines
2.3 KiB
Diff
63 lines
2.3 KiB
Diff
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From 56e0f123dc17cb99f50efbae4bbbab77f360818f Mon Sep 17 00:00:00 2001
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From: Matt Caswell <matt@openssl.org>
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Date: Mon, 3 Dec 2018 18:14:57 +0000
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Subject: [PATCH] Revert "Reduce stack usage in tls13_hkdf_expand"
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This reverts commit ec0c5f5693e39c5a013f81e6dd9dfd09ec65162d.
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SSL_export_keying_material() may use longer label lengths.
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Fixes #7712
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Reviewed-by: Tim Hudson <tjh@openssl.org>
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(Merged from https://github.com/openssl/openssl/pull/7755)
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(cherry picked from commit ed371b8cbac0d0349667558c061c1ae380cf75eb)
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Signed-off-by: Bernd Kuhls <bernd.kuhls@t-online.de>
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---
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ssl/tls13_enc.c | 16 ++++------------
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1 file changed, 4 insertions(+), 12 deletions(-)
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diff --git a/ssl/tls13_enc.c b/ssl/tls13_enc.c
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index b6825d20c2..f7ab0fa470 100644
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--- a/ssl/tls13_enc.c
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+++ b/ssl/tls13_enc.c
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@@ -13,14 +13,7 @@
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#include <openssl/evp.h>
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#include <openssl/kdf.h>
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-/*
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- * RFC 8446, 7.1 Key Schedule, says:
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- * Note: With common hash functions, any label longer than 12 characters
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- * requires an additional iteration of the hash function to compute.
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- * The labels in this specification have all been chosen to fit within
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- * this limit.
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- */
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-#define TLS13_MAX_LABEL_LEN 12
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+#define TLS13_MAX_LABEL_LEN 246
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/* Always filled with zeros */
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static const unsigned char default_zeros[EVP_MAX_MD_SIZE];
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@@ -36,15 +29,14 @@ int tls13_hkdf_expand(SSL *s, const EVP_MD *md, const unsigned char *secret,
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const unsigned char *data, size_t datalen,
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unsigned char *out, size_t outlen)
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{
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- static const unsigned char label_prefix[] = "tls13 ";
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+ const unsigned char label_prefix[] = "tls13 ";
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EVP_PKEY_CTX *pctx = EVP_PKEY_CTX_new_id(EVP_PKEY_HKDF, NULL);
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int ret;
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size_t hkdflabellen;
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size_t hashlen;
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/*
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- * 2 bytes for length of derived secret + 1 byte for length of combined
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- * prefix and label + bytes for the label itself + 1 byte length of hash
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- * + bytes for the hash itself
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+ * 2 bytes for length of whole HkdfLabel + 1 byte for length of combined
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+ * prefix and label + bytes for the label itself + bytes for the hash
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*/
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unsigned char hkdflabel[sizeof(uint16_t) + sizeof(uint8_t) +
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+ sizeof(label_prefix) + TLS13_MAX_LABEL_LEN
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--
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2.20.1
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