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Fix handshake defragmentation when the record has multiple messages
A handshake record may contain multiple handshake messages, or multiple fragments (there can be the final fragment of a pending message, then zero or more whole messages, and an initial fragment of an incomplete message). This was previously untested, but supported, so don't break it. Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
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@ -3055,6 +3055,15 @@ int mbedtls_ssl_prepare_handshake_record(mbedtls_ssl_context *ssl)
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unsigned char *const payload_start =
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reassembled_record_start + mbedtls_ssl_in_hdr_len(ssl);
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unsigned char *payload_end = payload_start + ssl->in_hsfraglen;
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/* How many more bytes we want to have a complete handshake message. */
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const size_t hs_remain = ssl->in_hslen - ssl->in_hsfraglen;
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/* How many bytes of the current record are part of the first
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* handshake message. There may be more handshake messages (possibly
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* incomplete) in the same record; if so, we leave them after the
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* current record, and ssl_consume_current_message() will take
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* care of consuming the next handshake message. */
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const size_t hs_this_fragment_len =
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ssl->in_msglen > hs_remain ? hs_remain : ssl->in_msglen;
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if (ssl->in_hsfraglen != 0) {
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/* We already had a handshake fragment. Prepare to append
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@ -3066,21 +3075,9 @@ int mbedtls_ssl_prepare_handshake_record(mbedtls_ssl_context *ssl)
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" of %" MBEDTLS_PRINTF_SIZET,
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ssl->in_msglen,
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ssl->in_hsfraglen,
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ssl->in_hsfraglen + ssl->in_msglen,
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ssl->in_hsfraglen + hs_this_fragment_len,
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ssl->in_hslen));
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const size_t hs_remain = ssl->in_hslen - ssl->in_hsfraglen;
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if (ssl->in_msglen > hs_remain) {
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MBEDTLS_SSL_DEBUG_MSG(1, ("Handshake fragment too long: %"
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MBEDTLS_PRINTF_SIZET " but only %"
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MBEDTLS_PRINTF_SIZET " of %"
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MBEDTLS_PRINTF_SIZET " remain",
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ssl->in_msglen,
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hs_remain,
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ssl->in_hslen));
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return MBEDTLS_ERR_SSL_INVALID_RECORD;
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}
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} else if (ssl->in_msglen == ssl->in_hslen) {
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} else if (hs_this_fragment_len == ssl->in_hslen) {
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/* This is the sole fragment. */
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/* Emit a log message in the same format as when there are
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* multiple fragments, for ease of matching. */
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@ -3091,7 +3088,7 @@ int mbedtls_ssl_prepare_handshake_record(mbedtls_ssl_context *ssl)
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" of %" MBEDTLS_PRINTF_SIZET,
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ssl->in_msglen,
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ssl->in_hsfraglen,
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ssl->in_hsfraglen + ssl->in_msglen,
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ssl->in_hsfraglen + hs_this_fragment_len,
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ssl->in_hslen));
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} else {
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/* This is the first fragment of many. */
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@ -3102,7 +3099,7 @@ int mbedtls_ssl_prepare_handshake_record(mbedtls_ssl_context *ssl)
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" of %" MBEDTLS_PRINTF_SIZET,
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ssl->in_msglen,
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ssl->in_hsfraglen,
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ssl->in_hsfraglen + ssl->in_msglen,
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ssl->in_hsfraglen + hs_this_fragment_len,
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ssl->in_hslen));
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}
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@ -3154,16 +3151,24 @@ int mbedtls_ssl_prepare_handshake_record(mbedtls_ssl_context *ssl)
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/* Update the record length in the fully reassembled record */
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if (ssl->in_msglen > 0xffff) {
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MBEDTLS_SSL_DEBUG_MSG(1,
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("Shouldn't happen: in_msglen=%"
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("Shouldn't happen: in_hslen=%"
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MBEDTLS_PRINTF_SIZET " > 0xffff",
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ssl->in_msglen));
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return MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
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}
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MBEDTLS_PUT_UINT16_BE(ssl->in_msglen, ssl->in_len, 0);
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size_t record_len = mbedtls_ssl_in_hdr_len(ssl) + ssl->in_msglen;
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MBEDTLS_SSL_DEBUG_BUF(4, "reassembled record",
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ssl->in_hdr,
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mbedtls_ssl_in_hdr_len(ssl) + ssl->in_msglen);
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ssl->in_hdr, record_len);
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if (ssl->in_hslen < ssl->in_msglen) {
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MBEDTLS_SSL_DEBUG_MSG(3,
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("More handshake messages in the record: "
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"%" MBEDTLS_PRINTF_SIZET " + "
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"%" MBEDTLS_PRINTF_SIZET,
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ssl->in_hslen,
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ssl->in_msglen - ssl->in_hslen));
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}
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}
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}
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