#include <openssl/evp.h>
#include <openssl/kdf.h>
-#define TLS13_MAX_LABEL_LEN 246
+#define TLS13_MAX_LABEL_LEN 249
/* Always filled with zeros */
static const unsigned char default_zeros[EVP_MAX_MD_SIZE];
* Given a |secret|; a |label| of length |labellen|; and |data| of length
* |datalen| (e.g. typically a hash of the handshake messages), derive a new
* secret |outlen| bytes long and store it in the location pointed to be |out|.
- * The |data| value may be zero length. Returns 1 on success 0 on failure.
+ * The |data| value may be zero length. Any errors will be treated as fatal if
+ * |fatal| is set. Returns 1 on success 0 on failure.
*/
int tls13_hkdf_expand(SSL *s, const EVP_MD *md, const unsigned char *secret,
const unsigned char *label, size_t labellen,
const unsigned char *data, size_t datalen,
- unsigned char *out, size_t outlen)
+ unsigned char *out, size_t outlen, int fatal)
{
- const unsigned char label_prefix[] = "tls13 ";
+ static const unsigned char label_prefix[] = "tls13 ";
EVP_PKEY_CTX *pctx = EVP_PKEY_CTX_new_id(EVP_PKEY_HKDF, NULL);
int ret;
size_t hkdflabellen;
size_t hashlen;
/*
- * 2 bytes for length of whole HkdfLabel + 1 byte for length of combined
- * prefix and label + bytes for the label itself + bytes for the hash
+ * 2 bytes for length of derived secret + 1 byte for length of combined
+ * prefix and label + bytes for the label itself + 1 byte length of hash
+ * + bytes for the hash itself
*/
unsigned char hkdflabel[sizeof(uint16_t) + sizeof(uint8_t) +
+ sizeof(label_prefix) + TLS13_MAX_LABEL_LEN
- + EVP_MAX_MD_SIZE];
+ + 1 + EVP_MAX_MD_SIZE];
WPACKET pkt;
if (pctx == NULL)
return 0;
+ if (labellen > TLS13_MAX_LABEL_LEN) {
+ if (fatal) {
+ SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS13_HKDF_EXPAND,
+ ERR_R_INTERNAL_ERROR);
+ } else {
+ /*
+ * Probably we have been called from SSL_export_keying_material(),
+ * or SSL_export_keying_material_early().
+ */
+ SSLerr(SSL_F_TLS13_HKDF_EXPAND, SSL_R_TLS_ILLEGAL_EXPORTER_LABEL);
+ }
+ EVP_PKEY_CTX_free(pctx);
+ return 0;
+ }
+
hashlen = EVP_MD_size(md);
if (!WPACKET_init_static_len(&pkt, hkdflabel, sizeof(hkdflabel), 0)
|| !WPACKET_finish(&pkt)) {
EVP_PKEY_CTX_free(pctx);
WPACKET_cleanup(&pkt);
- SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS13_HKDF_EXPAND,
- ERR_R_INTERNAL_ERROR);
+ if (fatal)
+ SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS13_HKDF_EXPAND,
+ ERR_R_INTERNAL_ERROR);
+ else
+ SSLerr(SSL_F_TLS13_HKDF_EXPAND, ERR_R_INTERNAL_ERROR);
return 0;
}
EVP_PKEY_CTX_free(pctx);
- if (ret != 0)
- SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS13_HKDF_EXPAND,
- ERR_R_INTERNAL_ERROR);
+ if (ret != 0) {
+ if (fatal)
+ SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS13_HKDF_EXPAND,
+ ERR_R_INTERNAL_ERROR);
+ else
+ SSLerr(SSL_F_TLS13_HKDF_EXPAND, ERR_R_INTERNAL_ERROR);
+ }
return ret == 0;
}
static const unsigned char keylabel[] = "key";
return tls13_hkdf_expand(s, md, secret, keylabel, sizeof(keylabel) - 1,
- NULL, 0, key, keylen);
+ NULL, 0, key, keylen, 1);
}
/*
static const unsigned char ivlabel[] = "iv";
return tls13_hkdf_expand(s, md, secret, ivlabel, sizeof(ivlabel) - 1,
- NULL, 0, iv, ivlen);
+ NULL, 0, iv, ivlen, 1);
}
int tls13_derive_finishedkey(SSL *s, const EVP_MD *md,
static const unsigned char finishedlabel[] = "finished";
return tls13_hkdf_expand(s, md, secret, finishedlabel,
- sizeof(finishedlabel) - 1, NULL, 0, fin, finlen);
+ sizeof(finishedlabel) - 1, NULL, 0, fin, finlen, 1);
}
/*
if (!tls13_hkdf_expand(s, md, prevsecret,
(unsigned char *)derived_secret_label,
sizeof(derived_secret_label) - 1, hash, mdlen,
- preextractsec, mdlen)) {
+ preextractsec, mdlen, 1)) {
/* SSLfatal() already called */
EVP_PKEY_CTX_free(pctx);
return 0;
hashlen = (size_t)hashleni;
if (!tls13_hkdf_expand(s, md, insecret, label, labellen, hash, hashlen,
- secret, hashlen)) {
+ secret, hashlen, 1)) {
/* SSLfatal() already called */
goto err;
}
early_exporter_master_secret,
sizeof(early_exporter_master_secret) - 1,
hashval, hashlen,
- s->early_exporter_master_secret, hashlen)) {
+ s->early_exporter_master_secret, hashlen,
+ 1)) {
SSLfatal(s, SSL_AD_INTERNAL_ERROR,
SSL_F_TLS13_CHANGE_CIPHER_STATE, ERR_R_INTERNAL_ERROR);
goto err;
resumption_master_secret,
sizeof(resumption_master_secret) - 1,
hashval, hashlen, s->resumption_master_secret,
- hashlen)) {
+ hashlen, 1)) {
/* SSLfatal() already called */
goto err;
}
exporter_master_secret,
sizeof(exporter_master_secret) - 1,
hash, hashlen, s->exporter_master_secret,
- hashlen)) {
+ hashlen, 1)) {
/* SSLfatal() already called */
goto err;
}
|| EVP_DigestFinal_ex(ctx, data, &datalen) <= 0
|| !tls13_hkdf_expand(s, md, s->exporter_master_secret,
(const unsigned char *)label, llen,
- data, datalen, exportsecret, hashsize)
+ data, datalen, exportsecret, hashsize, 0)
|| !tls13_hkdf_expand(s, md, exportsecret, exporterlabel,
sizeof(exporterlabel) - 1, hash, hashsize,
- out, olen))
+ out, olen, 0))
goto err;
ret = 1;
|| EVP_DigestFinal_ex(ctx, data, &datalen) <= 0
|| !tls13_hkdf_expand(s, md, s->early_exporter_master_secret,
(const unsigned char *)label, llen,
- data, datalen, exportsecret, hashsize)
+ data, datalen, exportsecret, hashsize, 0)
|| !tls13_hkdf_expand(s, md, exportsecret, exporterlabel,
sizeof(exporterlabel) - 1, hash, hashsize,
- out, olen))
+ out, olen, 0))
goto err;
ret = 1;
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