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Implement the V2ClientHello sniff in version-locked methods.

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Tested manually by replacing SSLv23_method() with TLSv1_2_method() in
bssl_shim. This is a large chunk of code which is not run in SSLv23_method(),
but it will be run after unification. It's split out separately to ease review.

Change-Id: I6bd241daca17aa0f9b3e36e51864a29755a41097
This commit is contained in:
David Benjamin 2014-12-12 03:58:07 -05:00 committed by Adam Langley
parent 63c55a8e35
commit 4b755cb0da
6 changed files with 352 additions and 47 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
include/openssl/ssl.h
View File

@ -2444,6 +2444,8 @@ OPENSSL_EXPORT void ERR_load_SSL_strings(void);
#define SSL_F_SSL_SESSION_to_bytes_full 292
#define SSL_F_SSL_accept 293
#define SSL_F_SSL_connect 294
#define SSL_F_ssl3_get_v2_client_hello 295
#define SSL_F_ssl3_get_initial_bytes 296
#define SSL_R_UNABLE_TO_FIND_ECDH_PARAMETERS 100
#define SSL_R_DECRYPTION_FAILED_OR_BAD_RECORD_MAC 101
#define SSL_R_INVALID_NULL_CMD_NAME 102

9
include/openssl/ssl3.h
View File

@ -369,6 +369,12 @@ typedef struct ssl3_state_st
* known. Otherwise the version has not been negotiated yet. */
char have_version;
/* sniff_buffer is used by the server in the initial handshake
* to read a V2ClientHello before the record layer is
* initialized. */
BUF_MEM *sniff_buffer;
size_t sniff_buffer_len;
SSL3_BUFFER rbuf; /* read IO goes into here */
SSL3_BUFFER wbuf; /* write IO goes into here */
@ -589,6 +595,8 @@ typedef struct ssl3_state_st
/* extra state */
#define SSL3_ST_SW_FLUSH (0x100|SSL_ST_ACCEPT)
/* read from client */
#define SSL3_ST_SR_INITIAL_BYTES (0x240|SSL_ST_ACCEPT)
#define SSL3_ST_SR_V2_CLIENT_HELLO (0x241|SSL_ST_ACCEPT)
/* Do not change the number values, they do matter */
#define SSL3_ST_SR_CLNT_HELLO_A (0x110|SSL_ST_ACCEPT)
#define SSL3_ST_SR_CLNT_HELLO_B (0x111|SSL_ST_ACCEPT)
@ -624,6 +632,7 @@ typedef struct ssl3_state_st
#define SSL3_ST_SR_CHANNEL_ID_B (0x231|SSL_ST_ACCEPT)
#define SSL3_ST_SR_FINISHED_A (0x1C0|SSL_ST_ACCEPT)
#define SSL3_ST_SR_FINISHED_B (0x1C1|SSL_ST_ACCEPT)
/* write to client */
#define SSL3_ST_SW_CHANGE_A (0x1D0|SSL_ST_ACCEPT)
#define SSL3_ST_SW_CHANGE_B (0x1D1|SSL_ST_ACCEPT)

7
ssl/s3_lib.c
View File

@ -1011,6 +1011,9 @@ void ssl3_free(SSL *s)
if(s == NULL)
return;
if (s->s3->sniff_buffer != NULL)
BUF_MEM_free(s->s3->sniff_buffer);
ssl3_cleanup_key_block(s);
if (s->s3->rbuf.buf != NULL)
ssl3_release_read_buffer(s);
@ -1053,6 +1056,10 @@ void ssl3_clear(SSL *s)
* ssl3_new. rbuf, wbuf, and init_extra are preserved, but
* this may not serve anything more than saving a malloc. */
if (s->s3->sniff_buffer != NULL)
BUF_MEM_free(s->s3->sniff_buffer);
s->s3->sniff_buffer = NULL;
ssl3_cleanup_key_block(s);
if (s->s3->tmp.ca_names != NULL)
sk_X509_NAME_pop_free(s->s3->tmp.ca_names,X509_NAME_free);

377
ssl/s3_srvr.c
View File

@ -172,6 +172,10 @@
#include "../crypto/internal.h"
#include "../crypto/dh/internal.h"
/* INITIAL_SNIFF_BUFFER_SIZE is the number of bytes read in the initial sniff
* buffer. */
#define INITIAL_SNIFF_BUFFER_SIZE 8
int ssl3_accept(SSL *s)
{
BUF_MEM *buf = NULL;
@ -207,55 +211,33 @@ int ssl3_accept(SSL *s)
switch (s->state)
{
case SSL_ST_RENEGOTIATE:
s->renegotiate=1;
/* s->state=SSL_ST_ACCEPT; */
/* This state is the renegotiate entry point. It sends a
* HelloRequest and nothing else. */
s->renegotiate = 1;
case SSL_ST_ACCEPT:
case SSL_ST_BEFORE|SSL_ST_ACCEPT:
if (cb != NULL) cb(s,SSL_CB_HANDSHAKE_START,1);
if (cb != NULL)
cb(s, SSL_CB_HANDSHAKE_START, 1);
if (s->init_buf == NULL)
{
if ((buf=BUF_MEM_new()) == NULL)
buf = BUF_MEM_new();
if (!buf || !BUF_MEM_grow(buf, SSL3_RT_MAX_PLAIN_LENGTH))
{
ret= -1;
goto end;
}
if (!BUF_MEM_grow(buf,SSL3_RT_MAX_PLAIN_LENGTH))
{
ret= -1;
goto end;
}
s->init_buf=buf;
buf = NULL;
}
if (!ssl3_setup_buffers(s))
{
ret= -1;
goto end;
}
s->init_num=0;
if (s->state != SSL_ST_RENEGOTIATE)
{
/* Ok, we now need to push on a buffering BIO so that
* the output is sent in a way that TCP likes :-)
*/
if (!ssl_init_wbio_buffer(s,1)) { ret= -1; goto end; }
if (!ssl3_init_finished_mac(s))
{
OPENSSL_PUT_ERROR(SSL, ssl3_accept, ERR_R_INTERNAL_ERROR);
ret = -1;
goto end;
}
s->state=SSL3_ST_SR_CLNT_HELLO_A;
s->ctx->stats.sess_accept++;
s->init_buf = buf;
buf = NULL;
}
else if (!s->s3->send_connection_binding &&
s->init_num = 0;
if (!ssl3_setup_buffers(s))
{
ret = -1;
goto end;
}
if (!s->s3->send_connection_binding &&
!(s->options & SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION))
{
/* Server attempting to renegotiate with
@ -267,13 +249,9 @@ int ssl3_accept(SSL *s)
ret = -1;
goto end;
}
else
{
/* s->state == SSL_ST_RENEGOTIATE,
* we will just send a HelloRequest */
s->ctx->stats.sess_accept_renegotiate++;
s->state=SSL3_ST_SW_HELLO_REQ_A;
}
s->ctx->stats.sess_accept_renegotiate++;
s->state = SSL3_ST_SW_HELLO_REQ_A;
break;
case SSL3_ST_SW_HELLO_REQ_A:
@ -298,6 +276,75 @@ int ssl3_accept(SSL *s)
s->state=SSL_ST_OK;
break;
case SSL_ST_ACCEPT:
case SSL_ST_BEFORE|SSL_ST_ACCEPT:
/* This state is the entry point for the handshake
* itself (initial and renegotiation). */
if (cb != NULL)
cb(s, SSL_CB_HANDSHAKE_START, 1);
if (s->init_buf == NULL)
{
buf = BUF_MEM_new();
if (!buf || !BUF_MEM_grow(buf, SSL3_RT_MAX_PLAIN_LENGTH))
{
ret = -1;
goto end;
}
s->init_buf = buf;
buf = NULL;
}
s->init_num = 0;
if (!ssl3_init_finished_mac(s))
{
OPENSSL_PUT_ERROR(SSL, ssl3_accept, ERR_R_INTERNAL_ERROR);
ret = -1;
goto end;
}
if (!s->s3->have_version)
{
/* This is the initial handshake. The record
* layer has not been initialized yet. Sniff for
* a V2ClientHello before reading a ClientHello
* normally. */
assert(s->s3->rbuf.buf == NULL);
assert(s->s3->wbuf.buf == NULL);
s->state = SSL3_ST_SR_INITIAL_BYTES;
}
else
{
/* Enable a write buffer. This groups handshake
* messages within a flight into a single
* write. */
if (!ssl3_setup_buffers(s) ||
!ssl_init_wbio_buffer(s, 1))
{
ret = -1;
goto end;
}
s->state = SSL3_ST_SR_CLNT_HELLO_A;
}
s->ctx->stats.sess_accept++;
break;
case SSL3_ST_SR_INITIAL_BYTES:
ret = ssl3_get_initial_bytes(s);
if (ret <= 0)
goto end;
/* ssl3_get_initial_bytes sets s->state to one of
* SSL3_ST_SR_V2_CLIENT_HELLO or SSL3_ST_SR_CLNT_HELLO_A
* on success. */
break;
case SSL3_ST_SR_V2_CLIENT_HELLO:
ret = ssl3_get_v2_client_hello(s);
if (ret <= 0)
goto end;
s->state = SSL3_ST_SR_CLNT_HELLO_A;
break;
case SSL3_ST_SR_CLNT_HELLO_A:
case SSL3_ST_SR_CLNT_HELLO_B:
case SSL3_ST_SR_CLNT_HELLO_C:
@ -674,6 +721,242 @@ end:
return(ret);
}
static int ssl3_read_sniff_buffer(SSL *s, size_t n)
{
if (s->s3->sniff_buffer == NULL)
{
s->s3->sniff_buffer = BUF_MEM_new();
}
if (s->s3->sniff_buffer == NULL ||
!BUF_MEM_grow(s->s3->sniff_buffer, n))
{
return -1;
}
while (s->s3->sniff_buffer_len < n)
{
int ret;
s->rwstate = SSL_READING;
ret = BIO_read(s->rbio,
s->s3->sniff_buffer->data + s->s3->sniff_buffer_len,
n - s->s3->sniff_buffer_len);
if (ret <= 0)
return ret;
s->rwstate = SSL_NOTHING;
s->s3->sniff_buffer_len += ret;
}
return 1;
}
int ssl3_get_initial_bytes(SSL *s)
{
int ret;
const uint8_t *p;
/* Read the first 8 bytes. To recognize a ClientHello or V2ClientHello
* only needs the first 6 bytes, but 8 is needed to recognize CONNECT
* below. */
ret = ssl3_read_sniff_buffer(s, INITIAL_SNIFF_BUFFER_SIZE);
if (ret <= 0)
return ret;
assert(s->s3->sniff_buffer_len >= INITIAL_SNIFF_BUFFER_SIZE);
p = (const uint8_t *)s->s3->sniff_buffer->data;
/* Some dedicated error codes for protocol mixups should the application
* wish to interpret them differently. (These do not overlap with
* ClientHello or V2ClientHello.) */
if (strncmp("GET ", (const char *)p, 4) == 0 ||
strncmp("POST ", (const char *)p, 5) == 0 ||
strncmp("HEAD ", (const char *)p, 5) == 0 ||
strncmp("PUT ", (const char *)p, 4) == 0)
{
OPENSSL_PUT_ERROR(SSL, ssl3_get_initial_bytes, SSL_R_HTTP_REQUEST);
return -1;
}
if (strncmp("CONNECT ", (const char *)p, 8) == 0)
{
OPENSSL_PUT_ERROR(SSL, ssl3_get_initial_bytes, SSL_R_HTTPS_PROXY_REQUEST);
return -1;
}
/* Determine if this is a ClientHello or V2ClientHello. */
if (p[0] & 0x80 && p[2] == SSL2_MT_CLIENT_HELLO &&
p[3] >= SSL3_VERSION_MAJOR)
{
/* This is a V2ClientHello. */
s->state = SSL3_ST_SR_V2_CLIENT_HELLO;
return 1;
}
if (p[0] == SSL3_RT_HANDSHAKE && p[1] >= SSL3_VERSION_MAJOR &&
p[5] == SSL3_MT_CLIENT_HELLO)
{
/* This is a ClientHello. Initialize the record layer with the
* already consumed data and continue the handshake. */
if (!ssl3_setup_buffers(s) || !ssl_init_wbio_buffer(s, 1))
{
return -1;
}
assert(s->rstate == SSL_ST_READ_HEADER);
memcpy(s->s3->rbuf.buf, p, s->s3->sniff_buffer_len);
s->s3->rbuf.offset = 0;
s->s3->rbuf.left = s->s3->sniff_buffer_len;
s->packet_length = 0;
BUF_MEM_free(s->s3->sniff_buffer);
s->s3->sniff_buffer = NULL;
s->s3->sniff_buffer_len = 0;
s->state = SSL3_ST_SR_CLNT_HELLO_A;
return 1;
}
OPENSSL_PUT_ERROR(SSL, ssl3_get_initial_bytes, SSL_R_UNKNOWN_PROTOCOL);
return -1;
}
int ssl3_get_v2_client_hello(SSL *s)
{
const uint8_t *p;
int ret;
CBS v2_client_hello, cipher_specs, session_id, challenge;
size_t msg_length, rand_len, len;
uint8_t msg_type;
uint16_t version, cipher_spec_length, session_id_length, challenge_length;
CBB client_hello, hello_body, cipher_suites;
uint8_t random[SSL3_RANDOM_SIZE];
/* Read the remainder of the V2ClientHello. We have previously read 8
* bytes in ssl3_get_initial_bytes. */
assert(s->s3->sniff_buffer_len >= INITIAL_SNIFF_BUFFER_SIZE);
p = (const uint8_t *)s->s3->sniff_buffer->data;
msg_length = ((p[0] & 0x7f) << 8) | p[1];
if (msg_length > (1024 * 4))
{
OPENSSL_PUT_ERROR(SSL, ssl3_get_v2_client_hello, SSL_R_RECORD_TOO_LARGE);
return -1;
}
if (msg_length < INITIAL_SNIFF_BUFFER_SIZE - 2)
{
/* Reject lengths that are too short early. We have already read
* 8 bytes, so we should not attempt to process an (invalid)
* V2ClientHello which would be shorter than that. */
OPENSSL_PUT_ERROR(SSL, ssl3_get_v2_client_hello, SSL_R_RECORD_LENGTH_MISMATCH);
return -1;
}
ret = ssl3_read_sniff_buffer(s, msg_length + 2);
if (ret <= 0)
return ret;
assert(s->s3->sniff_buffer_len == msg_length + 2);
CBS_init(&v2_client_hello,
(const uint8_t *)s->s3->sniff_buffer->data + 2, msg_length);
/* The V2ClientHello without the length is incorporated into the
* Finished hash. */
ssl3_finish_mac(s, CBS_data(&v2_client_hello), CBS_len(&v2_client_hello));
if (s->msg_callback)
s->msg_callback(0, SSL2_VERSION, 0, CBS_data(&v2_client_hello),
CBS_len(&v2_client_hello), s, s->msg_callback_arg);
if (!CBS_get_u8(&v2_client_hello, &msg_type) ||
!CBS_get_u16(&v2_client_hello, &version) ||
!CBS_get_u16(&v2_client_hello, &cipher_spec_length) ||
!CBS_get_u16(&v2_client_hello, &session_id_length) ||
!CBS_get_u16(&v2_client_hello, &challenge_length) ||
!CBS_get_bytes(&v2_client_hello, &cipher_specs, cipher_spec_length) ||
!CBS_get_bytes(&v2_client_hello, &session_id, session_id_length) ||
!CBS_get_bytes(&v2_client_hello, &challenge, challenge_length) ||
CBS_len(&v2_client_hello) != 0)
{
OPENSSL_PUT_ERROR(SSL, ssl3_get_v2_client_hello, SSL_R_DECODE_ERROR);
return -1;
}
/* msg_type has already been checked. */
assert(msg_type == SSL2_MT_CLIENT_HELLO);
/* The client_random is the V2ClientHello challenge. Truncate or
* left-pad with zeros as needed. */
memset(random, 0, SSL3_RANDOM_SIZE);
rand_len = CBS_len(&challenge);
if (rand_len > SSL3_RANDOM_SIZE)
rand_len = SSL3_RANDOM_SIZE;
memcpy(random + (SSL3_RANDOM_SIZE - rand_len), CBS_data(&challenge), rand_len);
/* Write out an equivalent SSLv3 ClientHello. */
if (!CBB_init_fixed(&client_hello, (uint8_t *)s->init_buf->data, s->init_buf->max))
{
OPENSSL_PUT_ERROR(SSL, ssl3_get_v2_client_hello, ERR_R_MALLOC_FAILURE);
return -1;
}
if (!CBB_add_u8(&client_hello, SSL3_MT_CLIENT_HELLO) ||
!CBB_add_u24_length_prefixed(&client_hello, &hello_body) ||
!CBB_add_u16(&hello_body, version) ||
!CBB_add_bytes(&hello_body, random, SSL3_RANDOM_SIZE) ||
/* No session id. */
!CBB_add_u8(&hello_body, 0) ||
!CBB_add_u16_length_prefixed(&hello_body, &cipher_suites))
{
CBB_cleanup(&client_hello);
OPENSSL_PUT_ERROR(SSL, ssl3_get_v2_client_hello, ERR_R_INTERNAL_ERROR);
return -1;
}
/* Copy the cipher suites. */
while (CBS_len(&cipher_specs) > 0)
{
uint32_t cipher_spec;
if (!CBS_get_u24(&cipher_specs, &cipher_spec))
{
CBB_cleanup(&client_hello);
OPENSSL_PUT_ERROR(SSL, ssl3_get_v2_client_hello, SSL_R_DECODE_ERROR);
return -1;
}
/* Skip SSLv2 ciphers. */
if ((cipher_spec & 0xff0000) != 0)
continue;
if (!CBB_add_u16(&cipher_suites, cipher_spec))
{
CBB_cleanup(&client_hello);
OPENSSL_PUT_ERROR(SSL, ssl3_get_v2_client_hello, ERR_R_INTERNAL_ERROR);
return -1;
}
}
/* Add the null compression scheme and finish. */
if (!CBB_add_u8(&hello_body, 1) ||
!CBB_add_u8(&hello_body, 0) ||
!CBB_finish(&client_hello, NULL, &len))
{
CBB_cleanup(&client_hello);
OPENSSL_PUT_ERROR(SSL, ssl3_get_v2_client_hello, ERR_R_INTERNAL_ERROR);
return -1;
}
/* Mark the message for "re"-use by the version-specific
* method. */
s->s3->tmp.reuse_message = 1;
s->s3->tmp.message_type = SSL3_MT_CLIENT_HELLO;
/* The handshake message header is 4 bytes. */
s->s3->tmp.message_size = len - 4;
/* Initialize the record layer. */
if (!ssl3_setup_buffers(s) || !ssl_init_wbio_buffer(s, 1))
{
return -1;
}
/* Drop the sniff buffer. */
BUF_MEM_free(s->s3->sniff_buffer);
s->s3->sniff_buffer = NULL;
s->s3->sniff_buffer_len = 0;
return 1;
}
int ssl3_send_hello_request(SSL *s)
{

2
ssl/ssl_error.c
View File

@ -126,6 +126,7 @@ const ERR_STRING_DATA SSL_error_string_data[] = {
{ERR_PACK(ERR_LIB_SSL, SSL_F_ssl3_get_client_hello, 0), "ssl3_get_client_hello"},
{ERR_PACK(ERR_LIB_SSL, SSL_F_ssl3_get_client_key_exchange, 0), "ssl3_get_client_key_exchange"},
{ERR_PACK(ERR_LIB_SSL, SSL_F_ssl3_get_finished, 0), "ssl3_get_finished"},
{ERR_PACK(ERR_LIB_SSL, SSL_F_ssl3_get_initial_bytes, 0), "ssl3_get_initial_bytes"},
{ERR_PACK(ERR_LIB_SSL, SSL_F_ssl3_get_message, 0), "ssl3_get_message"},
{ERR_PACK(ERR_LIB_SSL, SSL_F_ssl3_get_new_session_ticket, 0), "ssl3_get_new_session_ticket"},
{ERR_PACK(ERR_LIB_SSL, SSL_F_ssl3_get_next_proto, 0), "ssl3_get_next_proto"},
@ -134,6 +135,7 @@ const ERR_STRING_DATA SSL_error_string_data[] = {
{ERR_PACK(ERR_LIB_SSL, SSL_F_ssl3_get_server_done, 0), "ssl3_get_server_done"},
{ERR_PACK(ERR_LIB_SSL, SSL_F_ssl3_get_server_hello, 0), "ssl3_get_server_hello"},
{ERR_PACK(ERR_LIB_SSL, SSL_F_ssl3_get_server_key_exchange, 0), "ssl3_get_server_key_exchange"},
{ERR_PACK(ERR_LIB_SSL, SSL_F_ssl3_get_v2_client_hello, 0), "ssl3_get_v2_client_hello"},
{ERR_PACK(ERR_LIB_SSL, SSL_F_ssl3_handshake_mac, 0), "ssl3_handshake_mac"},
{ERR_PACK(ERR_LIB_SSL, SSL_F_ssl3_read_bytes, 0), "ssl3_read_bytes"},
{ERR_PACK(ERR_LIB_SSL, SSL_F_ssl3_read_n, 0), "ssl3_read_n"},

2
ssl/ssl_locl.h
View File

@ -945,6 +945,8 @@ int ssl3_send_channel_id(SSL *s);
int dtls1_client_hello(SSL *s);
/* some server-only functions */
int ssl3_get_initial_bytes(SSL *s);
int ssl3_get_v2_client_hello(SSL *s);
int ssl3_get_client_hello(SSL *s);
int ssl3_send_server_hello(SSL *s);
int ssl3_send_hello_request(SSL *s);