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openssl/ssl/record/ssl3_record.c
Matt Caswell f9cf774cbd Ensure we unpad in constant time for read pipelining 
The read pipelining code broke constant time unpadding. See GitHub
issue #1438

Reviewed-by: Rich Salz <rsalz@openssl.org>
2016-08-16 16:53:17 +01:00

1626 lines
55 KiB
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/*
* Copyright 1995-2016 The OpenSSL Project Authors. All Rights Reserved.
*
* Licensed under the OpenSSL license (the "License"). You may not use
* this file except in compliance with the License. You can obtain a copy
* in the file LICENSE in the source distribution or at
* https://www.openssl.org/source/license.html
*/
#include "../ssl_locl.h"
#include "internal/constant_time_locl.h"
#include <openssl/rand.h>
#include "record_locl.h"
static const unsigned char ssl3_pad_1[48] = {
0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36,
0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36,
0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36,
0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36,
0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36,
0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36
};
static const unsigned char ssl3_pad_2[48] = {
0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c,
0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c,
0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c,
0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c,
0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c,
0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c
};
/*
* Clear the contents of an SSL3_RECORD but retain any memory allocated
*/
void SSL3_RECORD_clear(SSL3_RECORD *r, unsigned int num_recs)
{
unsigned char *comp;
unsigned int i;
for (i = 0; i < num_recs; i++) {
comp = r[i].comp;
memset(&r[i], 0, sizeof(*r));
r[i].comp = comp;
}
}
void SSL3_RECORD_release(SSL3_RECORD *r, unsigned int num_recs)
{
unsigned int i;
for (i = 0; i < num_recs; i++) {
OPENSSL_free(r[i].comp);
r[i].comp = NULL;
}
}
void SSL3_RECORD_set_seq_num(SSL3_RECORD *r, const unsigned char *seq_num)
{
memcpy(r->seq_num, seq_num, SEQ_NUM_SIZE);
}
/*
* Peeks ahead into "read_ahead" data to see if we have a whole record waiting
* for us in the buffer.
*/
static int ssl3_record_app_data_waiting(SSL *s)
{
SSL3_BUFFER *rbuf;
int left, len;
unsigned char *p;
rbuf = RECORD_LAYER_get_rbuf(&s->rlayer);
p = SSL3_BUFFER_get_buf(rbuf);
if (p == NULL)
return 0;
left = SSL3_BUFFER_get_left(rbuf);
if (left < SSL3_RT_HEADER_LENGTH)
return 0;
p += SSL3_BUFFER_get_offset(rbuf);
/*
* We only check the type and record length, we will sanity check version
* etc later
*/
if (*p != SSL3_RT_APPLICATION_DATA)
return 0;
p += 3;
n2s(p, len);
if (left < SSL3_RT_HEADER_LENGTH + len)
return 0;
return 1;
}
/*
* MAX_EMPTY_RECORDS defines the number of consecutive, empty records that
* will be processed per call to ssl3_get_record. Without this limit an
* attacker could send empty records at a faster rate than we can process and
* cause ssl3_get_record to loop forever.
*/
#define MAX_EMPTY_RECORDS 32
#define SSL2_RT_HEADER_LENGTH 2
/*-
* Call this to get new input records.
* It will return <= 0 if more data is needed, normally due to an error
* or non-blocking IO.
* When it finishes, |numrpipes| records have been decoded. For each record 'i':
* rr[i].type - is the type of record
* rr[i].data, - data
* rr[i].length, - number of bytes
* Multiple records will only be returned if the record types are all
* SSL3_RT_APPLICATION_DATA. The number of records returned will always be <=
* |max_pipelines|
*/
/* used only by ssl3_read_bytes */
int ssl3_get_record(SSL *s)
{
int ssl_major, ssl_minor, al;
int enc_err, n, i, ret = -1;
SSL3_RECORD *rr;
SSL3_BUFFER *rbuf;
SSL_SESSION *sess;
unsigned char *p;
unsigned char md[EVP_MAX_MD_SIZE];
short version;
unsigned mac_size;
unsigned int num_recs = 0;
unsigned int max_recs;
unsigned int j;
rr = RECORD_LAYER_get_rrec(&s->rlayer);
rbuf = RECORD_LAYER_get_rbuf(&s->rlayer);
max_recs = s->max_pipelines;
if (max_recs == 0)
max_recs = 1;
sess = s->session;
do {
/* check if we have the header */
if ((RECORD_LAYER_get_rstate(&s->rlayer) != SSL_ST_READ_BODY) ||
(RECORD_LAYER_get_packet_length(&s->rlayer)
< SSL3_RT_HEADER_LENGTH)) {
n = ssl3_read_n(s, SSL3_RT_HEADER_LENGTH,
SSL3_BUFFER_get_len(rbuf), 0, num_recs == 0 ? 1 : 0);
if (n <= 0)
return (n); /* error or non-blocking */
RECORD_LAYER_set_rstate(&s->rlayer, SSL_ST_READ_BODY);
p = RECORD_LAYER_get_packet(&s->rlayer);
/*
* The first record received by the server may be a V2ClientHello.
*/
if (s->server && RECORD_LAYER_is_first_record(&s->rlayer)
&& (p[0] & 0x80) && (p[2] == SSL2_MT_CLIENT_HELLO)) {
/*
* SSLv2 style record
*
* |num_recs| here will actually always be 0 because
* |num_recs > 0| only ever occurs when we are processing
* multiple app data records - which we know isn't the case here
* because it is an SSLv2ClientHello. We keep it using
* |num_recs| for the sake of consistency
*/
rr[num_recs].type = SSL3_RT_HANDSHAKE;
rr[num_recs].rec_version = SSL2_VERSION;
rr[num_recs].length = ((p[0] & 0x7f) << 8) | p[1];
if (rr[num_recs].length > SSL3_BUFFER_get_len(rbuf)
- SSL2_RT_HEADER_LENGTH) {
al = SSL_AD_RECORD_OVERFLOW;
SSLerr(SSL_F_SSL3_GET_RECORD, SSL_R_PACKET_LENGTH_TOO_LONG);
goto f_err;
}
if (rr[num_recs].length < MIN_SSL2_RECORD_LEN) {
al = SSL_AD_HANDSHAKE_FAILURE;
SSLerr(SSL_F_SSL3_GET_RECORD, SSL_R_LENGTH_TOO_SHORT);
goto f_err;
}
} else {
/* SSLv3+ style record */
if (s->msg_callback)
s->msg_callback(0, 0, SSL3_RT_HEADER, p, 5, s,
s->msg_callback_arg);
/* Pull apart the header into the SSL3_RECORD */
rr[num_recs].type = *(p++);
ssl_major = *(p++);
ssl_minor = *(p++);
version = (ssl_major << 8) | ssl_minor;
rr[num_recs].rec_version = version;
n2s(p, rr[num_recs].length);
/* Lets check version */
if (!s->first_packet && version != s->version) {
SSLerr(SSL_F_SSL3_GET_RECORD, SSL_R_WRONG_VERSION_NUMBER);
if ((s->version & 0xFF00) == (version & 0xFF00)
&& !s->enc_write_ctx && !s->write_hash) {
if (rr->type == SSL3_RT_ALERT) {
/*
* The record is using an incorrect version number,
* but what we've got appears to be an alert. We
* haven't read the body yet to check whether its a
* fatal or not - but chances are it is. We probably
* shouldn't send a fatal alert back. We'll just
* end.
*/
goto err;
}
/*
* Send back error using their minor version number :-)
*/
s->version = (unsigned short)version;
}
al = SSL_AD_PROTOCOL_VERSION;
goto f_err;
}
if ((version >> 8) != SSL3_VERSION_MAJOR) {
if (RECORD_LAYER_is_first_record(&s->rlayer)) {
/* Go back to start of packet, look at the five bytes
* that we have. */
p = RECORD_LAYER_get_packet(&s->rlayer);
if (strncmp((char *)p, "GET ", 4) == 0 ||
strncmp((char *)p, "POST ", 5) == 0 ||
strncmp((char *)p, "HEAD ", 5) == 0 ||
strncmp((char *)p, "PUT ", 4) == 0) {
SSLerr(SSL_F_SSL3_GET_RECORD, SSL_R_HTTP_REQUEST);
goto err;
} else if (strncmp((char *)p, "CONNE", 5) == 0) {
SSLerr(SSL_F_SSL3_GET_RECORD,
SSL_R_HTTPS_PROXY_REQUEST);
goto err;
}
/* Doesn't look like TLS - don't send an alert */
SSLerr(SSL_F_SSL3_GET_RECORD,
SSL_R_WRONG_VERSION_NUMBER);
goto err;
} else {
SSLerr(SSL_F_SSL3_GET_RECORD,
SSL_R_WRONG_VERSION_NUMBER);
al = SSL_AD_PROTOCOL_VERSION;
goto f_err;
}
}
if (rr[num_recs].length >
SSL3_BUFFER_get_len(rbuf) - SSL3_RT_HEADER_LENGTH) {
al = SSL_AD_RECORD_OVERFLOW;
SSLerr(SSL_F_SSL3_GET_RECORD, SSL_R_PACKET_LENGTH_TOO_LONG);
goto f_err;
}
}
/* now s->rlayer.rstate == SSL_ST_READ_BODY */
}
/*
* s->rlayer.rstate == SSL_ST_READ_BODY, get and decode the data.
* Calculate how much more data we need to read for the rest of the
* record
*/
if (rr[num_recs].rec_version == SSL2_VERSION) {
i = rr[num_recs].length + SSL2_RT_HEADER_LENGTH
- SSL3_RT_HEADER_LENGTH;
} else {
i = rr[num_recs].length;
}
if (i > 0) {
/* now s->packet_length == SSL3_RT_HEADER_LENGTH */
n = ssl3_read_n(s, i, i, 1, 0);
if (n <= 0)
return (n); /* error or non-blocking io */
}
/* set state for later operations */
RECORD_LAYER_set_rstate(&s->rlayer, SSL_ST_READ_HEADER);
/*
* At this point, s->packet_length == SSL3_RT_HEADER_LENGTH + rr->length,
* or s->packet_length == SSL2_RT_HEADER_LENGTH + rr->length
* and we have that many bytes in s->packet
*/
if (rr[num_recs].rec_version == SSL2_VERSION) {
rr[num_recs].input =
&(RECORD_LAYER_get_packet(&s->rlayer)[SSL2_RT_HEADER_LENGTH]);
} else {
rr[num_recs].input =
&(RECORD_LAYER_get_packet(&s->rlayer)[SSL3_RT_HEADER_LENGTH]);
}
/*
* ok, we can now read from 's->packet' data into 'rr' rr->input points
* at rr->length bytes, which need to be copied into rr->data by either
* the decryption or by the decompression When the data is 'copied' into
* the rr->data buffer, rr->input will be pointed at the new buffer
*/
/*
* We now have - encrypted [ MAC [ compressed [ plain ] ] ] rr->length
* bytes of encrypted compressed stuff.
*/
/* check is not needed I believe */
if (rr[num_recs].length > SSL3_RT_MAX_ENCRYPTED_LENGTH) {
al = SSL_AD_RECORD_OVERFLOW;
SSLerr(SSL_F_SSL3_GET_RECORD, SSL_R_ENCRYPTED_LENGTH_TOO_LONG);
goto f_err;
}
/* decrypt in place in 'rr->input' */
rr[num_recs].data = rr[num_recs].input;
rr[num_recs].orig_len = rr[num_recs].length;
/* Mark this record as not read by upper layers yet */
rr[num_recs].read = 0;
num_recs++;
/* we have pulled in a full packet so zero things */
RECORD_LAYER_reset_packet_length(&s->rlayer);
RECORD_LAYER_clear_first_record(&s->rlayer);
} while (num_recs < max_recs
&& rr[num_recs-1].type == SSL3_RT_APPLICATION_DATA
&& SSL_USE_EXPLICIT_IV(s)
&& s->enc_read_ctx != NULL
&& (EVP_CIPHER_flags(EVP_CIPHER_CTX_cipher(s->enc_read_ctx))
& EVP_CIPH_FLAG_PIPELINE)
&& ssl3_record_app_data_waiting(s));
/*
* If in encrypt-then-mac mode calculate mac from encrypted record. All
* the details below are public so no timing details can leak.
*/
if (SSL_USE_ETM(s) && s->read_hash) {
unsigned char *mac;
mac_size = EVP_MD_CTX_size(s->read_hash);
OPENSSL_assert(mac_size <= EVP_MAX_MD_SIZE);
for (j = 0; j < num_recs; j++) {
if (rr[j].length < mac_size) {
al = SSL_AD_DECODE_ERROR;
SSLerr(SSL_F_SSL3_GET_RECORD, SSL_R_LENGTH_TOO_SHORT);
goto f_err;
}
rr[j].length -= mac_size;
mac = rr[j].data + rr[j].length;
i = s->method->ssl3_enc->mac(s, &rr[j], md, 0 /* not send */ );
if (i < 0 || CRYPTO_memcmp(md, mac, (size_t)mac_size) != 0) {
al = SSL_AD_BAD_RECORD_MAC;
SSLerr(SSL_F_SSL3_GET_RECORD,
SSL_R_DECRYPTION_FAILED_OR_BAD_RECORD_MAC);
goto f_err;
}
}
}
enc_err = s->method->ssl3_enc->enc(s, rr, num_recs, 0);
/*-
* enc_err is:
* 0: (in non-constant time) if the record is publically invalid.
* 1: if the padding is valid
* -1: if the padding is invalid
*/
if (enc_err == 0) {
al = SSL_AD_DECRYPTION_FAILED;
SSLerr(SSL_F_SSL3_GET_RECORD, SSL_R_BLOCK_CIPHER_PAD_IS_WRONG);
goto f_err;
}
#ifdef SSL_DEBUG
printf("dec %d\n", rr->length);
{
unsigned int z;
for (z = 0; z < rr->length; z++)
printf("%02X%c", rr->data[z], ((z + 1) % 16) ? ' ' : '\n');
}
printf("\n");
#endif
/* r->length is now the compressed data plus mac */
if ((sess != NULL) &&
(s->enc_read_ctx != NULL) &&
(EVP_MD_CTX_md(s->read_hash) != NULL) && !SSL_USE_ETM(s)) {
/* s->read_hash != NULL => mac_size != -1 */
unsigned char *mac = NULL;
unsigned char mac_tmp[EVP_MAX_MD_SIZE];
mac_size = EVP_MD_CTX_size(s->read_hash);
OPENSSL_assert(mac_size <= EVP_MAX_MD_SIZE);
for (j=0; j < num_recs; j++) {
/*
* orig_len is the length of the record before any padding was
* removed. This is public information, as is the MAC in use,
* therefore we can safely process the record in a different amount
* of time if it's too short to possibly contain a MAC.
*/
if (rr[j].orig_len < mac_size ||
/* CBC records must have a padding length byte too. */
(EVP_CIPHER_CTX_mode(s->enc_read_ctx) == EVP_CIPH_CBC_MODE &&
rr[j].orig_len < mac_size + 1)) {
al = SSL_AD_DECODE_ERROR;
SSLerr(SSL_F_SSL3_GET_RECORD, SSL_R_LENGTH_TOO_SHORT);
goto f_err;
}
if (EVP_CIPHER_CTX_mode(s->enc_read_ctx) == EVP_CIPH_CBC_MODE) {
/*
* We update the length so that the TLS header bytes can be
* constructed correctly but we need to extract the MAC in
* constant time from within the record, without leaking the
* contents of the padding bytes.
*/
mac = mac_tmp;
ssl3_cbc_copy_mac(mac_tmp, &rr[j], mac_size);
rr[j].length -= mac_size;
} else {
/*
* In this case there's no padding, so |rec->orig_len| equals
* |rec->length| and we checked that there's enough bytes for
* |mac_size| above.
*/
rr[j].length -= mac_size;
mac = &rr[j].data[rr[j].length];
}
i = s->method->ssl3_enc->mac(s, &rr[j], md, 0 /* not send */ );
if (i < 0 || mac == NULL
|| CRYPTO_memcmp(md, mac, (size_t)mac_size) != 0)
enc_err = -1;
if (rr->length > SSL3_RT_MAX_COMPRESSED_LENGTH + mac_size)
enc_err = -1;
}
}
if (enc_err < 0) {
/*
* A separate 'decryption_failed' alert was introduced with TLS 1.0,
* SSL 3.0 only has 'bad_record_mac'. But unless a decryption
* failure is directly visible from the ciphertext anyway, we should
* not reveal which kind of error occurred -- this might become
* visible to an attacker (e.g. via a logfile)
*/
al = SSL_AD_BAD_RECORD_MAC;
SSLerr(SSL_F_SSL3_GET_RECORD,
SSL_R_DECRYPTION_FAILED_OR_BAD_RECORD_MAC);
goto f_err;
}
for (j = 0; j < num_recs; j++) {
/* rr[j].length is now just compressed */
if (s->expand != NULL) {
if (rr[j].length > SSL3_RT_MAX_COMPRESSED_LENGTH) {
al = SSL_AD_RECORD_OVERFLOW;
SSLerr(SSL_F_SSL3_GET_RECORD, SSL_R_COMPRESSED_LENGTH_TOO_LONG);
goto f_err;
}
if (!ssl3_do_uncompress(s, &rr[j])) {
al = SSL_AD_DECOMPRESSION_FAILURE;
SSLerr(SSL_F_SSL3_GET_RECORD, SSL_R_BAD_DECOMPRESSION);
goto f_err;
}
}
if (rr[j].length > SSL3_RT_MAX_PLAIN_LENGTH) {
al = SSL_AD_RECORD_OVERFLOW;
SSLerr(SSL_F_SSL3_GET_RECORD, SSL_R_DATA_LENGTH_TOO_LONG);
goto f_err;
}
rr[j].off = 0;
/*-
* So at this point the following is true
* rr[j].type is the type of record
* rr[j].length == number of bytes in record
* rr[j].off == offset to first valid byte
* rr[j].data == where to take bytes from, increment after use :-).
*/
/* just read a 0 length packet */
if (rr[j].length == 0) {
RECORD_LAYER_inc_empty_record_count(&s->rlayer);
if (RECORD_LAYER_get_empty_record_count(&s->rlayer)
> MAX_EMPTY_RECORDS) {
al = SSL_AD_UNEXPECTED_MESSAGE;
SSLerr(SSL_F_SSL3_GET_RECORD, SSL_R_RECORD_TOO_SMALL);
goto f_err;
}
} else {
RECORD_LAYER_reset_empty_record_count(&s->rlayer);
}
}
RECORD_LAYER_set_numrpipes(&s->rlayer, num_recs);
return 1;
f_err:
ssl3_send_alert(s, SSL3_AL_FATAL, al);
err:
return ret;
}
int ssl3_do_uncompress(SSL *ssl, SSL3_RECORD *rr)
{
#ifndef OPENSSL_NO_COMP
int i;
if (rr->comp == NULL) {
rr->comp = (unsigned char *)
OPENSSL_malloc(SSL3_RT_MAX_ENCRYPTED_LENGTH);
}
if (rr->comp == NULL)
return 0;
i = COMP_expand_block(ssl->expand, rr->comp,
SSL3_RT_MAX_PLAIN_LENGTH, rr->data,
(int)rr->length);
if (i < 0)
return 0;
else
rr->length = i;
rr->data = rr->comp;
#endif
return 1;
}
int ssl3_do_compress(SSL *ssl, SSL3_RECORD *wr)
{
#ifndef OPENSSL_NO_COMP
int i;
i = COMP_compress_block(ssl->compress, wr->data,
SSL3_RT_MAX_COMPRESSED_LENGTH,
wr->input, (int)wr->length);
if (i < 0)
return (0);
else
wr->length = i;
wr->input = wr->data;
#endif
return (1);
}
/*-
* ssl3_enc encrypts/decrypts |n_recs| records in |inrecs|
*
* Returns:
* 0: (in non-constant time) if the record is publically invalid (i.e. too
* short etc).
* 1: if the record's padding is valid / the encryption was successful.
* -1: if the record's padding is invalid or, if sending, an internal error
* occurred.
*/
int ssl3_enc(SSL *s, SSL3_RECORD *inrecs, unsigned int n_recs, int send)
{
SSL3_RECORD *rec;
EVP_CIPHER_CTX *ds;
unsigned long l;
int bs, i, mac_size = 0;
const EVP_CIPHER *enc;
rec = inrecs;
/*
* We shouldn't ever be called with more than one record in the SSLv3 case
*/
if (n_recs != 1)
return 0;
if (send) {
ds = s->enc_write_ctx;
if (s->enc_write_ctx == NULL)
enc = NULL;
else
enc = EVP_CIPHER_CTX_cipher(s->enc_write_ctx);
} else {
ds = s->enc_read_ctx;
if (s->enc_read_ctx == NULL)
enc = NULL;
else
enc = EVP_CIPHER_CTX_cipher(s->enc_read_ctx);
}
if ((s->session == NULL) || (ds == NULL) || (enc == NULL)) {
memmove(rec->data, rec->input, rec->length);
rec->input = rec->data;
} else {
l = rec->length;
bs = EVP_CIPHER_CTX_block_size(ds);
/* COMPRESS */
if ((bs != 1) && send) {
i = bs - ((int)l % bs);
/* we need to add 'i-1' padding bytes */
l += i;
/*
* the last of these zero bytes will be overwritten with the
* padding length.
*/
memset(&rec->input[rec->length], 0, i);
rec->length += i;
rec->input[l - 1] = (i - 1);
}
if (!send) {
if (l == 0 || l % bs != 0)
return 0;
/* otherwise, rec->length >= bs */
}
if (EVP_Cipher(ds, rec->data, rec->input, l) < 1)
return -1;
if (EVP_MD_CTX_md(s->read_hash) != NULL)
mac_size = EVP_MD_CTX_size(s->read_hash);
if ((bs != 1) && !send)
return ssl3_cbc_remove_padding(rec, bs, mac_size);
}
return (1);
}
/*-
* tls1_enc encrypts/decrypts |n_recs| in |recs|.
*
* Returns:
* 0: (in non-constant time) if the record is publically invalid (i.e. too
* short etc).
* 1: if the record's padding is valid / the encryption was successful.
* -1: if the record's padding/AEAD-authenticator is invalid or, if sending,
* an internal error occurred.
*/
int tls1_enc(SSL *s, SSL3_RECORD *recs, unsigned int n_recs, int send)
{
EVP_CIPHER_CTX *ds;
size_t reclen[SSL_MAX_PIPELINES];
unsigned char buf[SSL_MAX_PIPELINES][EVP_AEAD_TLS1_AAD_LEN];
int bs, i, j, k, pad = 0, ret, mac_size = 0;
const EVP_CIPHER *enc;
unsigned int ctr;
if (send) {
if (EVP_MD_CTX_md(s->write_hash)) {
int n = EVP_MD_CTX_size(s->write_hash);
OPENSSL_assert(n >= 0);
}
ds = s->enc_write_ctx;
if (s->enc_write_ctx == NULL)
enc = NULL;
else {
int ivlen;
enc = EVP_CIPHER_CTX_cipher(s->enc_write_ctx);
/* For TLSv1.1 and later explicit IV */
if (SSL_USE_EXPLICIT_IV(s)
&& EVP_CIPHER_mode(enc) == EVP_CIPH_CBC_MODE)
ivlen = EVP_CIPHER_iv_length(enc);
else
ivlen = 0;
if (ivlen > 1) {
for (ctr = 0; ctr < n_recs; ctr++) {
if (recs[ctr].data != recs[ctr].input) {
/*
* we can't write into the input stream: Can this ever
* happen?? (steve)
*/
SSLerr(SSL_F_TLS1_ENC, ERR_R_INTERNAL_ERROR);
return -1;
} else if (RAND_bytes(recs[ctr].input, ivlen) <= 0) {
SSLerr(SSL_F_TLS1_ENC, ERR_R_INTERNAL_ERROR);
return -1;
}
}
}
}
} else {
if (EVP_MD_CTX_md(s->read_hash)) {
int n = EVP_MD_CTX_size(s->read_hash);
OPENSSL_assert(n >= 0);
}
ds = s->enc_read_ctx;
if (s->enc_read_ctx == NULL)
enc = NULL;
else
enc = EVP_CIPHER_CTX_cipher(s->enc_read_ctx);
}
if ((s->session == NULL) || (ds == NULL) || (enc == NULL)) {
for (ctr = 0; ctr < n_recs; ctr++) {
memmove(recs[ctr].data, recs[ctr].input, recs[ctr].length);
recs[ctr].input = recs[ctr].data;
}
ret = 1;
} else {
bs = EVP_CIPHER_block_size(EVP_CIPHER_CTX_cipher(ds));
if (n_recs > 1) {
if (!(EVP_CIPHER_flags(EVP_CIPHER_CTX_cipher(ds))
& EVP_CIPH_FLAG_PIPELINE)) {
/*
* We shouldn't have been called with pipeline data if the
* cipher doesn't support pipelining
*/
SSLerr(SSL_F_TLS1_ENC, SSL_R_PIPELINE_FAILURE);
return -1;
}
}
for (ctr = 0; ctr < n_recs; ctr++) {
reclen[ctr] = recs[ctr].length;
if (EVP_CIPHER_flags(EVP_CIPHER_CTX_cipher(ds))
& EVP_CIPH_FLAG_AEAD_CIPHER) {
unsigned char *seq;
seq = send ? RECORD_LAYER_get_write_sequence(&s->rlayer)
: RECORD_LAYER_get_read_sequence(&s->rlayer);
if (SSL_IS_DTLS(s)) {
/* DTLS does not support pipelining */
unsigned char dtlsseq[9], *p = dtlsseq;
s2n(send ? DTLS_RECORD_LAYER_get_w_epoch(&s->rlayer) :
DTLS_RECORD_LAYER_get_r_epoch(&s->rlayer), p);
memcpy(p, &seq[2], 6);
memcpy(buf[ctr], dtlsseq, 8);
} else {
memcpy(buf[ctr], seq, 8);
for (i = 7; i >= 0; i--) { /* increment */
++seq[i];
if (seq[i] != 0)
break;
}
}
buf[ctr][8] = recs[ctr].type;
buf[ctr][9] = (unsigned char)(s->version >> 8);
buf[ctr][10] = (unsigned char)(s->version);
buf[ctr][11] = recs[ctr].length >> 8;
buf[ctr][12] = recs[ctr].length & 0xff;
pad = EVP_CIPHER_CTX_ctrl(ds, EVP_CTRL_AEAD_TLS1_AAD,
EVP_AEAD_TLS1_AAD_LEN, buf[ctr]);
if (pad <= 0)
return -1;
if (send) {
reclen[ctr] += pad;
recs[ctr].length += pad;
}
} else if ((bs != 1) && send) {
i = bs - ((int)reclen[ctr] % bs);
/* Add weird padding of upto 256 bytes */
/* we need to add 'i' padding bytes of value j */
j = i - 1;
for (k = (int)reclen[ctr]; k < (int)(reclen[ctr] + i); k++)
recs[ctr].input[k] = j;
reclen[ctr] += i;
recs[ctr].length += i;
}
if (!send) {
if (reclen[ctr] == 0 || reclen[ctr] % bs != 0)
return 0;
}
}
if (n_recs > 1) {
unsigned char *data[SSL_MAX_PIPELINES];
/* Set the output buffers */
for (ctr = 0; ctr < n_recs; ctr++) {
data[ctr] = recs[ctr].data;
}
if (EVP_CIPHER_CTX_ctrl(ds, EVP_CTRL_SET_PIPELINE_OUTPUT_BUFS,
n_recs, data) <= 0) {
SSLerr(SSL_F_TLS1_ENC, SSL_R_PIPELINE_FAILURE);
}
/* Set the input buffers */
for (ctr = 0; ctr < n_recs; ctr++) {
data[ctr] = recs[ctr].input;
}
if (EVP_CIPHER_CTX_ctrl(ds, EVP_CTRL_SET_PIPELINE_INPUT_BUFS,
n_recs, data) <= 0
|| EVP_CIPHER_CTX_ctrl(ds, EVP_CTRL_SET_PIPELINE_INPUT_LENS,
n_recs, reclen) <= 0) {
SSLerr(SSL_F_TLS1_ENC, SSL_R_PIPELINE_FAILURE);
return -1;
}
}
i = EVP_Cipher(ds, recs[0].data, recs[0].input, reclen[0]);
if ((EVP_CIPHER_flags(EVP_CIPHER_CTX_cipher(ds))
& EVP_CIPH_FLAG_CUSTOM_CIPHER)
? (i < 0)
: (i == 0))
return -1; /* AEAD can fail to verify MAC */
if (send == 0) {
if (EVP_CIPHER_mode(enc) == EVP_CIPH_GCM_MODE) {
for (ctr = 0; ctr < n_recs; ctr++) {
recs[ctr].data += EVP_GCM_TLS_EXPLICIT_IV_LEN;
recs[ctr].input += EVP_GCM_TLS_EXPLICIT_IV_LEN;
recs[ctr].length -= EVP_GCM_TLS_EXPLICIT_IV_LEN;
}
} else if (EVP_CIPHER_mode(enc) == EVP_CIPH_CCM_MODE) {
for (ctr = 0; ctr < n_recs; ctr++) {
recs[ctr].data += EVP_CCM_TLS_EXPLICIT_IV_LEN;
recs[ctr].input += EVP_CCM_TLS_EXPLICIT_IV_LEN;
recs[ctr].length -= EVP_CCM_TLS_EXPLICIT_IV_LEN;
}
}
}
ret = 1;
if (!SSL_USE_ETM(s) && EVP_MD_CTX_md(s->read_hash) != NULL)
mac_size = EVP_MD_CTX_size(s->read_hash);
if ((bs != 1) && !send) {
int tmpret;
for (ctr = 0; ctr < n_recs; ctr++) {
tmpret = tls1_cbc_remove_padding(s, &recs[ctr], bs, mac_size);
/*
* If tmpret == 0 then this means publicly invalid so we can
* short circuit things here. Otherwise we must respect constant
* time behaviour.
*/
if (tmpret == 0)
return 0;
ret = constant_time_select_int(constant_time_eq_int(tmpret, 1),
ret, -1);
}
}
if (pad && !send) {
for (ctr = 0; ctr < n_recs; ctr++) {
recs[ctr].length -= pad;
}
}
}
return ret;
}
int n_ssl3_mac(SSL *ssl, SSL3_RECORD *rec, unsigned char *md, int send)
{
unsigned char *mac_sec, *seq;
const EVP_MD_CTX *hash;
unsigned char *p, rec_char;
size_t md_size;
int npad;
int t;
if (send) {
mac_sec = &(ssl->s3->write_mac_secret[0]);
seq = RECORD_LAYER_get_write_sequence(&ssl->rlayer);
hash = ssl->write_hash;
} else {
mac_sec = &(ssl->s3->read_mac_secret[0]);
seq = RECORD_LAYER_get_read_sequence(&ssl->rlayer);
hash = ssl->read_hash;
}
t = EVP_MD_CTX_size(hash);
if (t < 0)
return -1;
md_size = t;
npad = (48 / md_size) * md_size;
if (!send &&
EVP_CIPHER_CTX_mode(ssl->enc_read_ctx) == EVP_CIPH_CBC_MODE &&
ssl3_cbc_record_digest_supported(hash)) {
/*
* This is a CBC-encrypted record. We must avoid leaking any
* timing-side channel information about how many blocks of data we
* are hashing because that gives an attacker a timing-oracle.
*/
/*-
* npad is, at most, 48 bytes and that's with MD5:
* 16 + 48 + 8 (sequence bytes) + 1 + 2 = 75.
*
* With SHA-1 (the largest hash speced for SSLv3) the hash size
* goes up 4, but npad goes down by 8, resulting in a smaller
* total size.
*/
unsigned char header[75];
unsigned j = 0;
memcpy(header + j, mac_sec, md_size);
j += md_size;
memcpy(header + j, ssl3_pad_1, npad);
j += npad;
memcpy(header + j, seq, 8);
j += 8;
header[j++] = rec->type;
header[j++] = rec->length >> 8;
header[j++] = rec->length & 0xff;
/* Final param == is SSLv3 */
if (ssl3_cbc_digest_record(hash,
md, &md_size,
header, rec->input,
rec->length + md_size, rec->orig_len,
mac_sec, md_size, 1) <= 0)
return -1;
} else {
unsigned int md_size_u;
/* Chop the digest off the end :-) */
EVP_MD_CTX *md_ctx = EVP_MD_CTX_new();
if (md_ctx == NULL)
return -1;
rec_char = rec->type;
p = md;
s2n(rec->length, p);
if (EVP_MD_CTX_copy_ex(md_ctx, hash) <= 0
|| EVP_DigestUpdate(md_ctx, mac_sec, md_size) <= 0
|| EVP_DigestUpdate(md_ctx, ssl3_pad_1, npad) <= 0
|| EVP_DigestUpdate(md_ctx, seq, 8) <= 0
|| EVP_DigestUpdate(md_ctx, &rec_char, 1) <= 0
|| EVP_DigestUpdate(md_ctx, md, 2) <= 0
|| EVP_DigestUpdate(md_ctx, rec->input, rec->length) <= 0
|| EVP_DigestFinal_ex(md_ctx, md, NULL) <= 0
|| EVP_MD_CTX_copy_ex(md_ctx, hash) <= 0
|| EVP_DigestUpdate(md_ctx, mac_sec, md_size) <= 0
|| EVP_DigestUpdate(md_ctx, ssl3_pad_2, npad) <= 0
|| EVP_DigestUpdate(md_ctx, md, md_size) <= 0
|| EVP_DigestFinal_ex(md_ctx, md, &md_size_u) <= 0) {
EVP_MD_CTX_reset(md_ctx);
return -1;
}
md_size = md_size_u;
EVP_MD_CTX_free(md_ctx);
}
ssl3_record_sequence_update(seq);
return (md_size);
}
int tls1_mac(SSL *ssl, SSL3_RECORD *rec, unsigned char *md, int send)
{
unsigned char *seq;
EVP_MD_CTX *hash;
size_t md_size;
int i;
EVP_MD_CTX *hmac = NULL, *mac_ctx;
unsigned char header[13];
int stream_mac = (send ? (ssl->mac_flags & SSL_MAC_FLAG_WRITE_MAC_STREAM)
: (ssl->mac_flags & SSL_MAC_FLAG_READ_MAC_STREAM));
int t;
if (send) {
seq = RECORD_LAYER_get_write_sequence(&ssl->rlayer);
hash = ssl->write_hash;
} else {
seq = RECORD_LAYER_get_read_sequence(&ssl->rlayer);
hash = ssl->read_hash;
}
t = EVP_MD_CTX_size(hash);
OPENSSL_assert(t >= 0);
md_size = t;
/* I should fix this up TLS TLS TLS TLS TLS XXXXXXXX */
if (stream_mac) {
mac_ctx = hash;
} else {
hmac = EVP_MD_CTX_new();
if (hmac == NULL
|| !EVP_MD_CTX_copy(hmac, hash))
return -1;
mac_ctx = hmac;
}
if (SSL_IS_DTLS(ssl)) {
unsigned char dtlsseq[8], *p = dtlsseq;
s2n(send ? DTLS_RECORD_LAYER_get_w_epoch(&ssl->rlayer) :
DTLS_RECORD_LAYER_get_r_epoch(&ssl->rlayer), p);
memcpy(p, &seq[2], 6);
memcpy(header, dtlsseq, 8);
} else
memcpy(header, seq, 8);
header[8] = rec->type;
header[9] = (unsigned char)(ssl->version >> 8);
header[10] = (unsigned char)(ssl->version);
header[11] = (rec->length) >> 8;
header[12] = (rec->length) & 0xff;
if (!send && !SSL_USE_ETM(ssl) &&
EVP_CIPHER_CTX_mode(ssl->enc_read_ctx) == EVP_CIPH_CBC_MODE &&
ssl3_cbc_record_digest_supported(mac_ctx)) {
/*
* This is a CBC-encrypted record. We must avoid leaking any
* timing-side channel information about how many blocks of data we
* are hashing because that gives an attacker a timing-oracle.
*/
/* Final param == not SSLv3 */
if (ssl3_cbc_digest_record(mac_ctx,
md, &md_size,
header, rec->input,
rec->length + md_size, rec->orig_len,
ssl->s3->read_mac_secret,
ssl->s3->read_mac_secret_size, 0) <= 0) {
EVP_MD_CTX_free(hmac);
return -1;
}
} else {
if (EVP_DigestSignUpdate(mac_ctx, header, sizeof(header)) <= 0
|| EVP_DigestSignUpdate(mac_ctx, rec->input, rec->length) <= 0
|| EVP_DigestSignFinal(mac_ctx, md, &md_size) <= 0) {
EVP_MD_CTX_free(hmac);
return -1;
}
if (!send && !SSL_USE_ETM(ssl) && FIPS_mode())
if (!tls_fips_digest_extra(ssl->enc_read_ctx,
mac_ctx, rec->input,
rec->length, rec->orig_len)) {
EVP_MD_CTX_free(hmac);
return -1;
}
}
EVP_MD_CTX_free(hmac);
#ifdef SSL_DEBUG
fprintf(stderr, "seq=");
{
int z;
for (z = 0; z < 8; z++)
fprintf(stderr, "%02X ", seq[z]);
fprintf(stderr, "\n");
}
fprintf(stderr, "rec=");
{
unsigned int z;
for (z = 0; z < rec->length; z++)
fprintf(stderr, "%02X ", rec->data[z]);
fprintf(stderr, "\n");
}
#endif
if (!SSL_IS_DTLS(ssl)) {
for (i = 7; i >= 0; i--) {
++seq[i];
if (seq[i] != 0)
break;
}
}
#ifdef SSL_DEBUG
{
unsigned int z;
for (z = 0; z < md_size; z++)
fprintf(stderr, "%02X ", md[z]);
fprintf(stderr, "\n");
}
#endif
return (md_size);
}
/*-
* ssl3_cbc_remove_padding removes padding from the decrypted, SSLv3, CBC
* record in |rec| by updating |rec->length| in constant time.
*
* block_size: the block size of the cipher used to encrypt the record.
* returns:
* 0: (in non-constant time) if the record is publicly invalid.
* 1: if the padding was valid
* -1: otherwise.
*/
int ssl3_cbc_remove_padding(SSL3_RECORD *rec,
unsigned block_size, unsigned mac_size)
{
unsigned padding_length, good;
const unsigned overhead = 1 /* padding length byte */ + mac_size;
/*
* These lengths are all public so we can test them in non-constant time.
*/
if (overhead > rec->length)
return 0;
padding_length = rec->data[rec->length - 1];
good = constant_time_ge(rec->length, padding_length + overhead);
/* SSLv3 requires that the padding is minimal. */
good &= constant_time_ge(block_size, padding_length + 1);
rec->length -= good & (padding_length + 1);
return constant_time_select_int(good, 1, -1);
}
/*-
* tls1_cbc_remove_padding removes the CBC padding from the decrypted, TLS, CBC
* record in |rec| in constant time and returns 1 if the padding is valid and
* -1 otherwise. It also removes any explicit IV from the start of the record
* without leaking any timing about whether there was enough space after the
* padding was removed.
*
* block_size: the block size of the cipher used to encrypt the record.
* returns:
* 0: (in non-constant time) if the record is publicly invalid.
* 1: if the padding was valid
* -1: otherwise.
*/
int tls1_cbc_remove_padding(const SSL *s,
SSL3_RECORD *rec,
unsigned block_size, unsigned mac_size)
{
unsigned padding_length, good, to_check, i;
const unsigned overhead = 1 /* padding length byte */ + mac_size;
/* Check if version requires explicit IV */
if (SSL_USE_EXPLICIT_IV(s)) {
/*
* These lengths are all public so we can test them in non-constant
* time.
*/
if (overhead + block_size > rec->length)
return 0;
/* We can now safely skip explicit IV */
rec->data += block_size;
rec->input += block_size;
rec->length -= block_size;
rec->orig_len -= block_size;
} else if (overhead > rec->length)
return 0;
padding_length = rec->data[rec->length - 1];
if (EVP_CIPHER_flags(EVP_CIPHER_CTX_cipher(s->enc_read_ctx)) & EVP_CIPH_FLAG_AEAD_CIPHER) {
/* padding is already verified */
rec->length -= padding_length + 1;
return 1;
}
good = constant_time_ge(rec->length, overhead + padding_length);
/*
* The padding consists of a length byte at the end of the record and
* then that many bytes of padding, all with the same value as the length
* byte. Thus, with the length byte included, there are i+1 bytes of
* padding. We can't check just |padding_length+1| bytes because that
* leaks decrypted information. Therefore we always have to check the
* maximum amount of padding possible. (Again, the length of the record
* is public information so we can use it.)
*/
to_check = 256; /* maximum amount of padding, inc length byte. */
if (to_check > rec->length)
to_check = rec->length;
for (i = 0; i < to_check; i++) {
unsigned char mask = constant_time_ge_8(padding_length, i);
unsigned char b = rec->data[rec->length - 1 - i];
/*
* The final |padding_length+1| bytes should all have the value
* |padding_length|. Therefore the XOR should be zero.
*/
good &= ~(mask & (padding_length ^ b));
}
/*
* If any of the final |padding_length+1| bytes had the wrong value, one
* or more of the lower eight bits of |good| will be cleared.
*/
good = constant_time_eq(0xff, good & 0xff);
rec->length -= good & (padding_length + 1);
return constant_time_select_int(good, 1, -1);
}
/*-
* ssl3_cbc_copy_mac copies |md_size| bytes from the end of |rec| to |out| in
* constant time (independent of the concrete value of rec->length, which may
* vary within a 256-byte window).
*
* ssl3_cbc_remove_padding or tls1_cbc_remove_padding must be called prior to
* this function.
*
* On entry:
* rec->orig_len >= md_size
* md_size <= EVP_MAX_MD_SIZE
*
* If CBC_MAC_ROTATE_IN_PLACE is defined then the rotation is performed with
* variable accesses in a 64-byte-aligned buffer. Assuming that this fits into
* a single or pair of cache-lines, then the variable memory accesses don't
* actually affect the timing. CPUs with smaller cache-lines [if any] are
* not multi-core and are not considered vulnerable to cache-timing attacks.
*/
#define CBC_MAC_ROTATE_IN_PLACE
void ssl3_cbc_copy_mac(unsigned char *out,
const SSL3_RECORD *rec, unsigned md_size)
{
#if defined(CBC_MAC_ROTATE_IN_PLACE)
unsigned char rotated_mac_buf[64 + EVP_MAX_MD_SIZE];
unsigned char *rotated_mac;
#else
unsigned char rotated_mac[EVP_MAX_MD_SIZE];
#endif
/*
* mac_end is the index of |rec->data| just after the end of the MAC.
*/
unsigned mac_end = rec->length;
unsigned mac_start = mac_end - md_size;
/*
* scan_start contains the number of bytes that we can ignore because the
* MAC's position can only vary by 255 bytes.
*/
unsigned scan_start = 0;
unsigned i, j;
unsigned div_spoiler;
unsigned rotate_offset;
OPENSSL_assert(rec->orig_len >= md_size);
OPENSSL_assert(md_size <= EVP_MAX_MD_SIZE);
#if defined(CBC_MAC_ROTATE_IN_PLACE)
rotated_mac = rotated_mac_buf + ((0 - (size_t)rotated_mac_buf) & 63);
#endif
/* This information is public so it's safe to branch based on it. */
if (rec->orig_len > md_size + 255 + 1)
scan_start = rec->orig_len - (md_size + 255 + 1);
/*
* div_spoiler contains a multiple of md_size that is used to cause the
* modulo operation to be constant time. Without this, the time varies
* based on the amount of padding when running on Intel chips at least.
* The aim of right-shifting md_size is so that the compiler doesn't
* figure out that it can remove div_spoiler as that would require it to
* prove that md_size is always even, which I hope is beyond it.
*/
div_spoiler = md_size >> 1;
div_spoiler <<= (sizeof(div_spoiler) - 1) * 8;
rotate_offset = (div_spoiler + mac_start - scan_start) % md_size;
memset(rotated_mac, 0, md_size);
for (i = scan_start, j = 0; i < rec->orig_len; i++) {
unsigned char mac_started = constant_time_ge_8(i, mac_start);
unsigned char mac_ended = constant_time_ge_8(i, mac_end);
unsigned char b = rec->data[i];
rotated_mac[j++] |= b & mac_started & ~mac_ended;
j &= constant_time_lt(j, md_size);
}
/* Now rotate the MAC */
#if defined(CBC_MAC_ROTATE_IN_PLACE)
j = 0;
for (i = 0; i < md_size; i++) {
/* in case cache-line is 32 bytes, touch second line */
((volatile unsigned char *)rotated_mac)[rotate_offset ^ 32];
out[j++] = rotated_mac[rotate_offset++];
rotate_offset &= constant_time_lt(rotate_offset, md_size);
}
#else
memset(out, 0, md_size);
rotate_offset = md_size - rotate_offset;
rotate_offset &= constant_time_lt(rotate_offset, md_size);
for (i = 0; i < md_size; i++) {
for (j = 0; j < md_size; j++)
out[j] |= rotated_mac[i] & constant_time_eq_8(j, rotate_offset);
rotate_offset++;
rotate_offset &= constant_time_lt(rotate_offset, md_size);
}
#endif
}
int dtls1_process_record(SSL *s)
{
int i, al;
int enc_err;
SSL_SESSION *sess;
SSL3_RECORD *rr;
unsigned int mac_size;
unsigned char md[EVP_MAX_MD_SIZE];
rr = RECORD_LAYER_get_rrec(&s->rlayer);
sess = s->session;
/*
* At this point, s->packet_length == SSL3_RT_HEADER_LNGTH + rr->length,
* and we have that many bytes in s->packet
*/
rr->input = &(RECORD_LAYER_get_packet(&s->rlayer)[DTLS1_RT_HEADER_LENGTH]);
/*
* ok, we can now read from 's->packet' data into 'rr' rr->input points
* at rr->length bytes, which need to be copied into rr->data by either
* the decryption or by the decompression When the data is 'copied' into
* the rr->data buffer, rr->input will be pointed at the new buffer
*/
/*
* We now have - encrypted [ MAC [ compressed [ plain ] ] ] rr->length
* bytes of encrypted compressed stuff.
*/
/* check is not needed I believe */
if (rr->length > SSL3_RT_MAX_ENCRYPTED_LENGTH) {
al = SSL_AD_RECORD_OVERFLOW;
SSLerr(SSL_F_DTLS1_PROCESS_RECORD, SSL_R_ENCRYPTED_LENGTH_TOO_LONG);
goto f_err;
}
/* decrypt in place in 'rr->input' */
rr->data = rr->input;
rr->orig_len = rr->length;
enc_err = s->method->ssl3_enc->enc(s, rr, 1, 0);
/*-
* enc_err is:
* 0: (in non-constant time) if the record is publically invalid.
* 1: if the padding is valid
* -1: if the padding is invalid
*/
if (enc_err == 0) {
/* For DTLS we simply ignore bad packets. */
rr->length = 0;
RECORD_LAYER_reset_packet_length(&s->rlayer);
goto err;
}
#ifdef SSL_DEBUG
printf("dec %d\n", rr->length);
{
unsigned int z;
for (z = 0; z < rr->length; z++)
printf("%02X%c", rr->data[z], ((z + 1) % 16) ? ' ' : '\n');
}
printf("\n");
#endif
/* r->length is now the compressed data plus mac */
if ((sess != NULL) &&
(s->enc_read_ctx != NULL) && (EVP_MD_CTX_md(s->read_hash) != NULL)) {
/* s->read_hash != NULL => mac_size != -1 */
unsigned char *mac = NULL;
unsigned char mac_tmp[EVP_MAX_MD_SIZE];
mac_size = EVP_MD_CTX_size(s->read_hash);
OPENSSL_assert(mac_size <= EVP_MAX_MD_SIZE);
/*
* orig_len is the length of the record before any padding was
* removed. This is public information, as is the MAC in use,
* therefore we can safely process the record in a different amount
* of time if it's too short to possibly contain a MAC.
*/
if (rr->orig_len < mac_size ||
/* CBC records must have a padding length byte too. */
(EVP_CIPHER_CTX_mode(s->enc_read_ctx) == EVP_CIPH_CBC_MODE &&
rr->orig_len < mac_size + 1)) {
al = SSL_AD_DECODE_ERROR;
SSLerr(SSL_F_DTLS1_PROCESS_RECORD, SSL_R_LENGTH_TOO_SHORT);
goto f_err;
}
if (EVP_CIPHER_CTX_mode(s->enc_read_ctx) == EVP_CIPH_CBC_MODE) {
/*
* We update the length so that the TLS header bytes can be
* constructed correctly but we need to extract the MAC in
* constant time from within the record, without leaking the
* contents of the padding bytes.
*/
mac = mac_tmp;
ssl3_cbc_copy_mac(mac_tmp, rr, mac_size);
rr->length -= mac_size;
} else {
/*
* In this case there's no padding, so |rec->orig_len| equals
* |rec->length| and we checked that there's enough bytes for
* |mac_size| above.
*/
rr->length -= mac_size;
mac = &rr->data[rr->length];
}
i = s->method->ssl3_enc->mac(s, rr, md, 0 /* not send */ );
if (i < 0 || mac == NULL
|| CRYPTO_memcmp(md, mac, (size_t)mac_size) != 0)
enc_err = -1;
if (rr->length > SSL3_RT_MAX_COMPRESSED_LENGTH + mac_size)
enc_err = -1;
}
if (enc_err < 0) {
/* decryption failed, silently discard message */
rr->length = 0;
RECORD_LAYER_reset_packet_length(&s->rlayer);
goto err;
}
/* r->length is now just compressed */
if (s->expand != NULL) {
if (rr->length > SSL3_RT_MAX_COMPRESSED_LENGTH) {
al = SSL_AD_RECORD_OVERFLOW;
SSLerr(SSL_F_DTLS1_PROCESS_RECORD,
SSL_R_COMPRESSED_LENGTH_TOO_LONG);
goto f_err;
}
if (!ssl3_do_uncompress(s, rr)) {
al = SSL_AD_DECOMPRESSION_FAILURE;
SSLerr(SSL_F_DTLS1_PROCESS_RECORD, SSL_R_BAD_DECOMPRESSION);
goto f_err;
}
}
if (rr->length > SSL3_RT_MAX_PLAIN_LENGTH) {
al = SSL_AD_RECORD_OVERFLOW;
SSLerr(SSL_F_DTLS1_PROCESS_RECORD, SSL_R_DATA_LENGTH_TOO_LONG);
goto f_err;
}
rr->off = 0;
/*-
* So at this point the following is true
* ssl->s3->rrec.type is the type of record
* ssl->s3->rrec.length == number of bytes in record
* ssl->s3->rrec.off == offset to first valid byte
* ssl->s3->rrec.data == where to take bytes from, increment
* after use :-).
*/
/* we have pulled in a full packet so zero things */
RECORD_LAYER_reset_packet_length(&s->rlayer);
return (1);
f_err:
ssl3_send_alert(s, SSL3_AL_FATAL, al);
err:
return (0);
}
/*
* retrieve a buffered record that belongs to the current epoch, ie,
* processed
*/
#define dtls1_get_processed_record(s) \
dtls1_retrieve_buffered_record((s), \
&(DTLS_RECORD_LAYER_get_processed_rcds(&s->rlayer)))
/*-
* Call this to get a new input record.
* It will return <= 0 if more data is needed, normally due to an error
* or non-blocking IO.
* When it finishes, one packet has been decoded and can be found in
* ssl->s3->rrec.type - is the type of record
* ssl->s3->rrec.data, - data
* ssl->s3->rrec.length, - number of bytes
*/
/* used only by dtls1_read_bytes */
int dtls1_get_record(SSL *s)
{
int ssl_major, ssl_minor;
int i, n;
SSL3_RECORD *rr;
unsigned char *p = NULL;
unsigned short version;
DTLS1_BITMAP *bitmap;
unsigned int is_next_epoch;
rr = RECORD_LAYER_get_rrec(&s->rlayer);
/*
* The epoch may have changed. If so, process all the pending records.
* This is a non-blocking operation.
*/
if (dtls1_process_buffered_records(s) < 0)
return -1;
/* if we're renegotiating, then there may be buffered records */
if (dtls1_get_processed_record(s))
return 1;
/* get something from the wire */
again:
/* check if we have the header */
if ((RECORD_LAYER_get_rstate(&s->rlayer) != SSL_ST_READ_BODY) ||
(RECORD_LAYER_get_packet_length(&s->rlayer) < DTLS1_RT_HEADER_LENGTH)) {
n = ssl3_read_n(s, DTLS1_RT_HEADER_LENGTH,
SSL3_BUFFER_get_len(&s->rlayer.rbuf), 0, 1);
/* read timeout is handled by dtls1_read_bytes */
if (n <= 0)
return (n); /* error or non-blocking */
/* this packet contained a partial record, dump it */
if (RECORD_LAYER_get_packet_length(&s->rlayer) != DTLS1_RT_HEADER_LENGTH) {
RECORD_LAYER_reset_packet_length(&s->rlayer);
goto again;
}
RECORD_LAYER_set_rstate(&s->rlayer, SSL_ST_READ_BODY);
p = RECORD_LAYER_get_packet(&s->rlayer);
if (s->msg_callback)
s->msg_callback(0, 0, SSL3_RT_HEADER, p, DTLS1_RT_HEADER_LENGTH,
s, s->msg_callback_arg);
/* Pull apart the header into the DTLS1_RECORD */
rr->type = *(p++);
ssl_major = *(p++);
ssl_minor = *(p++);
version = (ssl_major << 8) | ssl_minor;
/* sequence number is 64 bits, with top 2 bytes = epoch */
n2s(p, rr->epoch);
memcpy(&(RECORD_LAYER_get_read_sequence(&s->rlayer)[2]), p, 6);
p += 6;
n2s(p, rr->length);
/* Lets check version */
if (!s->first_packet) {
if (version != s->version) {
/* unexpected version, silently discard */
rr->length = 0;
RECORD_LAYER_reset_packet_length(&s->rlayer);
goto again;
}
}
if ((version & 0xff00) != (s->version & 0xff00)) {
/* wrong version, silently discard record */
rr->length = 0;
RECORD_LAYER_reset_packet_length(&s->rlayer);
goto again;
}
if (rr->length > SSL3_RT_MAX_ENCRYPTED_LENGTH) {
/* record too long, silently discard it */
rr->length = 0;
RECORD_LAYER_reset_packet_length(&s->rlayer);
goto again;
}
/* now s->rlayer.rstate == SSL_ST_READ_BODY */
}
/* s->rlayer.rstate == SSL_ST_READ_BODY, get and decode the data */
if (rr->length >
RECORD_LAYER_get_packet_length(&s->rlayer) - DTLS1_RT_HEADER_LENGTH) {
/* now s->packet_length == DTLS1_RT_HEADER_LENGTH */
i = rr->length;
n = ssl3_read_n(s, i, i, 1, 1);
/* this packet contained a partial record, dump it */
if (n != i) {
rr->length = 0;
RECORD_LAYER_reset_packet_length(&s->rlayer);
goto again;
}
/*
* now n == rr->length, and s->packet_length ==
* DTLS1_RT_HEADER_LENGTH + rr->length
*/
}
/* set state for later operations */
RECORD_LAYER_set_rstate(&s->rlayer, SSL_ST_READ_HEADER);
/* match epochs. NULL means the packet is dropped on the floor */
bitmap = dtls1_get_bitmap(s, rr, &is_next_epoch);
if (bitmap == NULL) {
rr->length = 0;
RECORD_LAYER_reset_packet_length(&s->rlayer); /* dump this record */
goto again; /* get another record */
}
#ifndef OPENSSL_NO_SCTP
/* Only do replay check if no SCTP bio */
if (!BIO_dgram_is_sctp(SSL_get_rbio(s))) {
#endif
/* Check whether this is a repeat, or aged record. */
if (!dtls1_record_replay_check(s, bitmap)) {
rr->length = 0;
RECORD_LAYER_reset_packet_length(&s->rlayer); /* dump this record */
goto again; /* get another record */
}
#ifndef OPENSSL_NO_SCTP
}
#endif
/* just read a 0 length packet */
if (rr->length == 0)
goto again;
/*
* If this record is from the next epoch (either HM or ALERT), and a
* handshake is currently in progress, buffer it since it cannot be
* processed at this time.
*/
if (is_next_epoch) {
if ((SSL_in_init(s) || ossl_statem_get_in_handshake(s))) {
if (dtls1_buffer_record
(s, &(DTLS_RECORD_LAYER_get_unprocessed_rcds(&s->rlayer)),
rr->seq_num) < 0)
return -1;
/* Mark receipt of record. */
dtls1_record_bitmap_update(s, bitmap);
}
rr->length = 0;
RECORD_LAYER_reset_packet_length(&s->rlayer);
goto again;
}
if (!dtls1_process_record(s)) {
rr->length = 0;
RECORD_LAYER_reset_packet_length(&s->rlayer); /* dump this record */
goto again; /* get another record */
}
dtls1_record_bitmap_update(s, bitmap); /* Mark receipt of record. */
return (1);
}
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