From 2aec073a529f8d8dc0e625b9c444db9de7b46873 Mon Sep 17 00:00:00 2001 From: Andy Polyakov Date: Fri, 1 Feb 2013 15:31:50 +0100 Subject: [PATCH] ssl/*: remove SSL3_RECORD->orig_len to restore binary compatibility. Kludge alert. This is arranged by passing padding length in unused bits of SSL3_RECORD->type, so that orig_len can be reconstructed. (cherry picked from commit 8bfd4c659f180a6ce34f21c0e62956b362067fba) --- ssl/d1_pkt.c | 12 ++++++------ ssl/s3_cbc.c | 21 ++++++++++++--------- ssl/s3_enc.c | 8 ++++++-- ssl/s3_pkt.c | 12 ++++++------ ssl/ssl3.h | 4 ---- ssl/ssl_locl.h | 2 +- ssl/t1_enc.c | 10 +++++++--- 7 files changed, 38 insertions(+), 31 deletions(-) diff --git a/ssl/d1_pkt.c b/ssl/d1_pkt.c index 02c881ab31..0ad8b5f559 100644 --- a/ssl/d1_pkt.c +++ b/ssl/d1_pkt.c @@ -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; diff --git a/ssl/s3_cbc.c b/ssl/s3_cbc.c index 52e294157e..b91d84098d 100644 --- a/ssl/s3_cbc.c +++ b/ssl/s3_cbc.c @@ -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); diff --git a/ssl/s3_enc.c b/ssl/s3_enc.c index 0282ef4620..196f0739d5 100644 --- a/ssl/s3_enc.c +++ b/ssl/s3_enc.c @@ -730,7 +730,7 @@ 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; @@ -755,6 +755,10 @@ 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)) @@ -786,7 +790,7 @@ 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 */); } diff --git a/ssl/s3_pkt.c b/ssl/s3_pkt.c index 032a8558ed..64cef2abfa 100644 --- a/ssl/s3_pkt.c +++ b/ssl/s3_pkt.c @@ -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); @@ -400,7 +400,7 @@ 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: @@ -436,10 +436,10 @@ 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); @@ -454,12 +454,12 @@ 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; diff --git a/ssl/ssl3.h b/ssl/ssl3.h index e41f288871..d2a5208824 100644 --- a/ssl/ssl3.h +++ b/ssl/ssl3.h @@ -372,10 +372,6 @@ 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 diff --git a/ssl/ssl_locl.h b/ssl/ssl_locl.h index 134198e91b..65c56bddc9 100644 --- a/ssl/ssl_locl.h +++ b/ssl/ssl_locl.h @@ -1275,7 +1275,7 @@ 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, diff --git a/ssl/t1_enc.c b/ssl/t1_enc.c index e313355fa2..4e23bbf77b 100644 --- a/ssl/t1_enc.c +++ b/ssl/t1_enc.c @@ -973,7 +973,7 @@ 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]; @@ -1020,6 +1020,10 @@ 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); @@ -1038,7 +1042,7 @@ 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 */); @@ -1054,7 +1058,7 @@ 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 } -- 2.34.1