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@

1 files changed, 1 insertions, 205 deletions

diff --git a/src/lib/libssl/ssl_packet.c b/src/lib/libssl/ssl_packet.c
index 70017b4664..32d6cceb7a 100644
--- a/src/lib/libssl/ssl_packet.c
+++ b/src/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>
  *
@@ -19,34 +19,6 @@
 #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)
 {
         uint16_t record_version;
@@ -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);