Remove handling of SSLv2 client hello messages.

This code was only previously enabled if the minimum enabled version was
TLSv1.0 and a non-version locked method is in use. Since TLSv1.0 and
TLSv1.1 were disabled nearly a year ago, this code is no longer ever
being used.

ok tb@

diff --git a/lib/libssl/ssl_packet.c b/lib/libssl/ssl_packet.c
index 70017b4..32d6cce 100644 (file)
--- a/lib/libssl/ssl_packet.c
+++ b/lib/libssl/ssl_packet.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: ssl_packet.c,v 1.15 2022/11/26 16:08:56 tb Exp $ */
+/* $OpenBSD: ssl_packet.c,v 1.16 2024/06/28 13:37:49 jsing Exp $ */
 /*
  * Copyright (c) 2016, 2017 Joel Sing <jsing@openbsd.org>
  *
@@ -18,34 +18,6 @@
 #include "bytestring.h"
 #include "ssl_local.h"
 
-static int
-ssl_is_sslv2_client_hello(CBS *header)
-{
-       uint16_t record_length;
-       uint8_t message_type;
-       CBS cbs;
-
-       CBS_dup(header, &cbs);
-
-       if (!CBS_get_u16(&cbs, &record_length) ||
-           !CBS_get_u8(&cbs, &message_type))
-               return 0;
-
-       /*
-        * The SSLv2 record length field uses variable length (2 or 3 byte)
-        * encoding. Given the size of a client hello, we expect/require the
-        * 2-byte form which is indicated by a one in the most significant bit.
-        */
-       if ((record_length & 0x8000) == 0)
-               return 0;
-       if ((record_length & ~0x8000) < 3)
-               return 0;
-       if (message_type != SSL2_MT_CLIENT_HELLO)
-               return 0;
-
-       return 1;
-}
-
 static int
 ssl_is_sslv3_handshake(CBS *header)
 {
@@ -67,164 +39,6 @@ ssl_is_sslv3_handshake(CBS *header)
        return 1;
 }
 
-static int
-ssl_convert_sslv2_client_hello(SSL *s)
-{
-       CBB cbb, handshake, client_hello, cipher_suites, compression, session_id;
-       CBS cbs, challenge, cipher_specs, session;
-       uint16_t record_length, client_version, cipher_specs_length;
-       uint16_t session_id_length, challenge_length;
-       unsigned char *client_random = NULL, *data = NULL;
-       size_t data_len, pad_len, len;
-       uint32_t cipher_spec;
-       uint8_t message_type;
-       unsigned char *pad;
-       int ret = -1;
-       int n;
-
-       memset(&cbb, 0, sizeof(cbb));
-
-       CBS_init(&cbs, s->packet, SSL3_RT_HEADER_LENGTH);
-
-       if (!CBS_get_u16(&cbs, &record_length) ||
-           !CBS_get_u8(&cbs, &message_type) ||
-           !CBS_get_u16(&cbs, &client_version))
-               return -1;
-
-       /*
-        * The SSLv2 record length field uses variable length (2 or 3 byte)
-        * encoding. Given the size of a client hello, we expect/require the
-        * 2-byte form which is indicated by a one in the most significant bit.
-        * Also note that the record length value does not include the bytes
-        * used for the record length field.
-        */
-       if ((record_length & 0x8000) == 0)
-               return -1;
-       record_length &= ~0x8000;
-       if (record_length < SSL3_RT_HEADER_LENGTH - 2)
-               return -1;
-       if (message_type != SSL2_MT_CLIENT_HELLO)
-               return -1;
-
-       if (record_length < 9) {
-               SSLerror(s, SSL_R_RECORD_LENGTH_MISMATCH);
-               return -1;
-       }
-       if (record_length > 4096) {
-               SSLerror(s, SSL_R_RECORD_TOO_LARGE);
-               return -1;
-       }
-
-       n = ssl3_packet_extend(s, record_length + 2);
-       if (n != record_length + 2)
-               return n;
-
-       tls1_transcript_record(s, s->packet + 2,
-           s->packet_length - 2);
-       s->mac_packet = 0;
-
-       if (s->msg_callback)
-               s->msg_callback(0, SSL2_VERSION, 0,
-                   s->packet + 2, s->packet_length - 2, s,
-                   s->msg_callback_arg);
-
-       /* Decode the SSLv2 record containing the client hello. */
-       CBS_init(&cbs, s->packet, s->packet_length);
-
-       if (!CBS_get_u16(&cbs, &record_length))
-               return -1;
-       if (!CBS_get_u8(&cbs, &message_type))
-               return -1;
-       if (!CBS_get_u16(&cbs, &client_version))
-               return -1;
-       if (!CBS_get_u16(&cbs, &cipher_specs_length))
-               return -1;
-       if (!CBS_get_u16(&cbs, &session_id_length))
-               return -1;
-       if (!CBS_get_u16(&cbs, &challenge_length))
-               return -1;
-       if (!CBS_get_bytes(&cbs, &cipher_specs, cipher_specs_length))
-               return -1;
-       if (!CBS_get_bytes(&cbs, &session, session_id_length))
-               return -1;
-       if (!CBS_get_bytes(&cbs, &challenge, challenge_length))
-               return -1;
-       if (CBS_len(&cbs) != 0) {
-               SSLerror(s, SSL_R_RECORD_LENGTH_MISMATCH);
-               return -1;
-       }
-
-       /*
-        * Convert SSLv2 challenge to SSLv3/TLS client random, by truncating or
-        * left-padding with zero bytes.
-        */
-       if ((client_random = malloc(SSL3_RANDOM_SIZE)) == NULL)
-               goto err;
-       if (!CBB_init_fixed(&cbb, client_random, SSL3_RANDOM_SIZE))
-               goto err;
-       if ((len = CBS_len(&challenge)) > SSL3_RANDOM_SIZE)
-               len = SSL3_RANDOM_SIZE;
-       pad_len = SSL3_RANDOM_SIZE - len;
-       if (!CBB_add_space(&cbb, &pad, pad_len))
-               goto err;
-       memset(pad, 0, pad_len);
-       if (!CBB_add_bytes(&cbb, CBS_data(&challenge), len))
-               goto err;
-       if (!CBB_finish(&cbb, NULL, NULL))
-               goto err;
-
-       /* Build SSLv3/TLS record with client hello. */
-       if (!CBB_init(&cbb, SSL3_RT_MAX_PLAIN_LENGTH))
-               goto err;
-       if (!CBB_add_u8(&cbb, SSL3_RT_HANDSHAKE))
-               goto err;
-       if (!CBB_add_u16(&cbb, 0x0301))
-               goto err;
-       if (!CBB_add_u16_length_prefixed(&cbb, &handshake))
-               goto err;
-       if (!CBB_add_u8(&handshake, SSL3_MT_CLIENT_HELLO))
-               goto err;
-       if (!CBB_add_u24_length_prefixed(&handshake, &client_hello))
-               goto err;
-       if (!CBB_add_u16(&client_hello, client_version))
-               goto err;
-       if (!CBB_add_bytes(&client_hello, client_random, SSL3_RANDOM_SIZE))
-               goto err;
-       if (!CBB_add_u8_length_prefixed(&client_hello, &session_id))
-               goto err;
-       if (!CBB_add_u16_length_prefixed(&client_hello, &cipher_suites))
-               goto err;
-       while (CBS_len(&cipher_specs) > 0) {
-               if (!CBS_get_u24(&cipher_specs, &cipher_spec))
-                       goto err;
-               if ((cipher_spec & 0xff0000) != 0)
-                       continue;
-               if (!CBB_add_u16(&cipher_suites, cipher_spec & 0xffff))
-                       goto err;
-       }
-       if (!CBB_add_u8_length_prefixed(&client_hello, &compression))
-               goto err;
-       if (!CBB_add_u8(&compression, 0))
-               goto err;
-       if (!CBB_finish(&cbb, &data, &data_len))
-               goto err;
-
-       if (data_len > s->s3->rbuf.len)
-               goto err;
-
-       s->packet = s->s3->rbuf.buf;
-       s->packet_length = data_len;
-       memcpy(s->packet, data, data_len);
-       ret = 1;
-
- err:
-       CBB_cleanup(&cbb);
-       free(client_random);
-       free(data);
-
-       return (ret);
-}
-
 /*
  * Potentially do legacy processing on the first packet received by a TLS
  * server. We return 1 if we want SSLv3/TLS record processing to continue
@@ -233,7 +47,6 @@ ssl_convert_sslv2_client_hello(SSL *s)
 int
 ssl_server_legacy_first_packet(SSL *s)
 {
-       uint16_t min_version;
        const char *data;
        CBS header;
 
@@ -249,23 +62,6 @@ ssl_server_legacy_first_packet(SSL *s)
        if (s->method->min_tls_version == s->method->max_tls_version)
                return 1;
 
-       if (ssl_is_sslv2_client_hello(&header) == 1) {
-               /* Only permit SSLv2 client hellos if TLSv1.0 is enabled. */
-               if (ssl_enabled_tls_version_range(s, &min_version, NULL) != 1) {
-                       SSLerror(s, SSL_R_NO_PROTOCOLS_AVAILABLE);
-                       return -1;
-               }
-               if (min_version > TLS1_VERSION)
-                       return 1;
-
-               if (ssl_convert_sslv2_client_hello(s) != 1) {
-                       SSLerror(s, SSL_R_BAD_PACKET_LENGTH);
-                       return -1;
-               }
-
-               return 1;
-       }
-
        /* Ensure that we have SSL3_RT_HEADER_LENGTH (5 bytes) of the packet. */
        if (CBS_len(&header) != SSL3_RT_HEADER_LENGTH) {
                SSLerror(s, ERR_R_INTERNAL_ERROR);