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ssl/*: remove SSL3_RECORD->orig_len to restore binary compatibility.

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Kludge alert. This is arranged by passing padding length in unused
bits of SSL3_RECORD->type, so that orig_len can be reconstructed.
This commit is contained in:
Andy Polyakov 2013-02-01 15:31:50 +01:00
parent 04e45b52ee
commit 8bfd4c659f
7 changed files with 38 additions and 31 deletions
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12
ssl/d1_pkt.c
View File

@ -379,7 +379,7 @@ dtls1_process_record(SSL *s)
int enc_err;
SSL_SESSION *sess;
SSL3_RECORD *rr;
unsigned int mac_size;
unsigned int mac_size, orig_len;
unsigned char md[EVP_MAX_MD_SIZE];
rr= &(s->s3->rrec);
@ -410,7 +410,7 @@ dtls1_process_record(SSL *s)
/* decrypt in place in 'rr->input' */
rr->data=rr->input;
rr->orig_len=rr->length;
orig_len=rr->length;
enc_err = s->method->ssl3_enc->enc(s,0);
/* enc_err is:
@ -447,10 +447,10 @@ printf("\n");
* 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 ||
if (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))
orig_len < mac_size+1))
{
al=SSL_AD_DECODE_ERROR;
SSLerr(SSL_F_SSL3_GET_RECORD,SSL_R_LENGTH_TOO_SHORT);
@ -465,12 +465,12 @@ printf("\n");
* without leaking the contents of the padding bytes.
* */
mac = mac_tmp;
ssl3_cbc_copy_mac(mac_tmp, rr, mac_size);
ssl3_cbc_copy_mac(mac_tmp, rr, mac_size, orig_len);
rr->length -= mac_size;
}
else
{
/* In this case there's no padding, so |rec->orig_len|
/* In this case there's no padding, so |orig_len|
* equals |rec->length| and we checked that there's
* enough bytes for |mac_size| above. */
rr->length -= mac_size;

21
ssl/s3_cbc.c
View File

@ -116,7 +116,9 @@ int ssl3_cbc_remove_padding(const SSL* s,
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);
padding_length = good & (padding_length+1);
rec->length -= padding_length;
rec->type |= padding_length<<8; /* kludge: pass padding length */
return (int)((good & 1) | (~good & -1));
}
@ -203,7 +205,9 @@ int tls1_cbc_remove_padding(const SSL* s,
good <<= sizeof(good)*8-1;
good = DUPLICATE_MSB_TO_ALL(good);
rec->length -= good & (padding_length+1);
padding_length = good & (padding_length+1);
rec->length -= padding_length;
rec->type |= padding_length<<8; /* kludge: pass padding length */
/* We can always safely skip the explicit IV. We check at the beginning
* of this function that the record has at least enough space for the
@ -218,7 +222,6 @@ int tls1_cbc_remove_padding(const SSL* s,
rec->data += block_size;
rec->input += block_size;
rec->length -= block_size;
rec->orig_len -= block_size;
}
return (int)((good & 1) | (~good & -1));
@ -246,7 +249,7 @@ int tls1_cbc_remove_padding(const SSL* s,
*/
void ssl3_cbc_copy_mac(unsigned char* out,
const SSL3_RECORD *rec,
unsigned md_size)
unsigned md_size,unsigned orig_len)
{
#if defined(CBC_MAC_ROTATE_IN_PLACE)
unsigned char rotated_mac_buf[EVP_MAX_MD_SIZE*2];
@ -265,7 +268,7 @@ void ssl3_cbc_copy_mac(unsigned char* out,
unsigned div_spoiler;
unsigned rotate_offset;
OPENSSL_assert(rec->orig_len >= md_size);
OPENSSL_assert(orig_len >= md_size);
OPENSSL_assert(md_size <= EVP_MAX_MD_SIZE);
#if defined(CBC_MAC_ROTATE_IN_PLACE)
@ -273,8 +276,8 @@ void ssl3_cbc_copy_mac(unsigned char* out,
#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);
if (orig_len > md_size + 255 + 1)
scan_start = 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.
@ -287,9 +290,9 @@ void ssl3_cbc_copy_mac(unsigned char* out,
rotate_offset = (div_spoiler + mac_start - scan_start) % md_size;
memset(rotated_mac, 0, md_size);
for (i = scan_start; i < rec->orig_len;)
for (i = scan_start; i < orig_len;)
{
for (j = 0; j < md_size && i < rec->orig_len; i++, j++)
for (j = 0; j < md_size && i < orig_len; i++, j++)
{
unsigned char mac_started = constant_time_ge(i, mac_start);
unsigned char mac_ended = constant_time_ge(i, mac_end);

8
ssl/s3_enc.c
View File

@ -709,7 +709,7 @@ int n_ssl3_mac(SSL *ssl, unsigned char *md, int send)
EVP_MD_CTX md_ctx;
const EVP_MD_CTX *hash;
unsigned char *p,rec_char;
size_t md_size;
size_t md_size, orig_len;
int npad;
int t;
@ -734,6 +734,10 @@ int n_ssl3_mac(SSL *ssl, unsigned char *md, int send)
md_size=t;
npad=(48/md_size)*md_size;
/* kludge: ssl3_cbc_remove_padding passes padding length in rec->type */
orig_len = rec->length+md_size+((unsigned int)rec->type>>8);
rec->type &= 0xff;
if (!send &&
EVP_CIPHER_CTX_mode(ssl->enc_read_ctx) == EVP_CIPH_CBC_MODE &&
ssl3_cbc_record_digest_supported(hash))
@ -765,7 +769,7 @@ int n_ssl3_mac(SSL *ssl, unsigned char *md, int send)
hash,
md, &md_size,
header, rec->input,
rec->length + md_size, rec->orig_len,
rec->length + md_size, orig_len,
mac_sec, md_size,
1 /* is SSLv3 */);
}

12
ssl/s3_pkt.c
View File

@ -290,7 +290,7 @@ static int ssl3_get_record(SSL *s)
unsigned char *p;
unsigned char md[EVP_MAX_MD_SIZE];
short version;
unsigned mac_size;
unsigned mac_size, orig_len;
size_t extra;
rr= &(s->s3->rrec);
@ -398,7 +398,7 @@ fprintf(stderr, "Record type=%d, Length=%d\n", rr->type, rr->length);
/* decrypt in place in 'rr->input' */
rr->data=rr->input;
rr->orig_len=rr->length;
orig_len=rr->length;
enc_err = s->method->ssl3_enc->enc(s,0);
/* enc_err is:
@ -434,10 +434,10 @@ printf("\n");
* 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 ||
if (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))
orig_len < mac_size+1))
{
al=SSL_AD_DECODE_ERROR;
SSLerr(SSL_F_SSL3_GET_RECORD,SSL_R_LENGTH_TOO_SHORT);
@ -452,12 +452,12 @@ printf("\n");
* without leaking the contents of the padding bytes.
* */
mac = mac_tmp;
ssl3_cbc_copy_mac(mac_tmp, rr, mac_size);
ssl3_cbc_copy_mac(mac_tmp, rr, mac_size, orig_len);
rr->length -= mac_size;
}
else
{
/* In this case there's no padding, so |rec->orig_len|
/* In this case there's no padding, so |orig_len|
* equals |rec->length| and we checked that there's
* enough bytes for |mac_size| above. */
rr->length -= mac_size;

4
ssl/ssl3.h
View File

@ -355,10 +355,6 @@ typedef struct ssl3_record_st
/*r */ unsigned char *comp; /* only used with decompression - malloc()ed */
/*r */ unsigned long epoch; /* epoch number, needed by DTLS1 */
/*r */ unsigned char seq_num[8]; /* sequence number, needed by DTLS1 */
/*rw*/ unsigned int orig_len; /* How many bytes were available before padding
was removed? This is used to implement the
MAC check in constant time for CBC records.
*/
} SSL3_RECORD;
typedef struct ssl3_buffer_st

2
ssl/ssl_locl.h
View File

@ -1145,7 +1145,7 @@ int ssl_parse_serverhello_use_srtp_ext(SSL *s, unsigned char *d, int len,int *al
/* s3_cbc.c */
void ssl3_cbc_copy_mac(unsigned char* out,
const SSL3_RECORD *rec,
unsigned md_size);
unsigned md_size,unsigned orig_len);
int ssl3_cbc_remove_padding(const SSL* s,
SSL3_RECORD *rec,
unsigned block_size,

10
ssl/t1_enc.c
View File

@ -949,7 +949,7 @@ int tls1_mac(SSL *ssl, unsigned char *md, int send)
SSL3_RECORD *rec;
unsigned char *seq;
EVP_MD_CTX *hash;
size_t md_size;
size_t md_size, orig_len;
int i;
EVP_MD_CTX hmac, *mac_ctx;
unsigned char header[13];
@ -996,6 +996,10 @@ int tls1_mac(SSL *ssl, unsigned char *md, int send)
else
memcpy(header, seq, 8);
/* kludge: tls1_cbc_remove_padding passes padding length in rec->type */
orig_len = rec->length+md_size+((unsigned int)rec->type>>8);
rec->type &= 0xff;
header[8]=rec->type;
header[9]=(unsigned char)(ssl->version>>8);
header[10]=(unsigned char)(ssl->version);
@ -1014,7 +1018,7 @@ int tls1_mac(SSL *ssl, unsigned char *md, int send)
mac_ctx,
md, &md_size,
header, rec->input,
rec->length + md_size, rec->orig_len,
rec->length + md_size, orig_len,
ssl->s3->read_mac_secret,
ssl->s3->read_mac_secret_size,
0 /* not SSLv3 */);
@ -1030,7 +1034,7 @@ int tls1_mac(SSL *ssl, unsigned char *md, int send)
tls_fips_digest_extra(
ssl->enc_read_ctx,
mac_ctx, rec->input,
rec->length, rec->orig_len);
rec->length, orig_len);
#endif
}