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Handle max_fragment_length overflow for DTLS

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Allow for encryption overhead in early DTLS size check
and send overflow if validated record is too long

Reviewed-by: Matt Caswell <matt@openssl.org>
Reviewed-by: Tomas Mraz <tmraz@fedoraproject.org>
(Merged from https://github.com/openssl/openssl/pull/11096)
This commit is contained in:
Simon Cornish 2020-02-14 14:16:09 -08:00 committed by Tomas Mraz
parent ce82b892e8
commit cc0663f697
1 changed files with 8 additions and 2 deletions
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10
ssl/record/ssl3_record.c
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@ -1630,6 +1630,7 @@ int dtls1_process_record(SSL *s, DTLS1_BITMAP *bitmap)
int imac_size;
size_t mac_size;
unsigned char md[EVP_MAX_MD_SIZE];
size_t max_plain_length = SSL3_RT_MAX_PLAIN_LENGTH;
rr = RECORD_LAYER_get_rrec(&s->rlayer);
sess = s->session;
@ -1797,7 +1798,12 @@ int dtls1_process_record(SSL *s, DTLS1_BITMAP *bitmap)
}
}
if (rr->length > SSL3_RT_MAX_PLAIN_LENGTH) {
/* use current Max Fragment Length setting if applicable */
if (s->session != NULL && USE_MAX_FRAGMENT_LENGTH_EXT(s->session))
max_plain_length = GET_MAX_FRAGMENT_LENGTH(s->session);
/* send overflow if the plaintext is too long now it has passed MAC */
if (rr->length > max_plain_length) {
SSLfatal(s, SSL_AD_RECORD_OVERFLOW, SSL_F_DTLS1_PROCESS_RECORD,
SSL_R_DATA_LENGTH_TOO_LONG);
return 0;
@ -1941,7 +1947,7 @@ int dtls1_get_record(SSL *s)
/* If received packet overflows own-client Max Fragment Length setting */
if (s->session != NULL && USE_MAX_FRAGMENT_LENGTH_EXT(s->session)
&& rr->length > GET_MAX_FRAGMENT_LENGTH(s->session)) {
&& rr->length > GET_MAX_FRAGMENT_LENGTH(s->session) + SSL3_RT_MAX_ENCRYPTED_OVERHEAD) {
/* record too long, silently discard it */
rr->length = 0;
rr->read = 1;