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-rw-r--r--ssl/d1_pkt.c12
-rw-r--r--ssl/s3_cbc.c54
-rw-r--r--ssl/s3_enc.c8
-rw-r--r--ssl/s3_pkt.c12
-rw-r--r--ssl/ssl3.h4
-rw-r--r--ssl/ssl_locl.h2
-rw-r--r--ssl/t1_enc.c10
7 files changed, 43 insertions, 59 deletions
diff --git a/ssl/d1_pkt.c b/ssl/d1_pkt.c
index 0ad8b5f559..02c881ab31 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, orig_len;
+ unsigned int mac_size;
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;
- orig_len=rr->length;
+ rr->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 (orig_len < mac_size ||
+ 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 &&
- orig_len < mac_size+1))
+ rr->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, orig_len);
+ ssl3_cbc_copy_mac(mac_tmp, rr, mac_size);
rr->length -= mac_size;
}
else
{
- /* In this case there's no padding, so |orig_len|
+ /* 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;
diff --git a/ssl/s3_cbc.c b/ssl/s3_cbc.c
index ce77acd3d4..2e9765e963 100644
--- a/ssl/s3_cbc.c
+++ b/ssl/s3_cbc.c
@@ -116,9 +116,7 @@ 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);
- padding_length = good & (padding_length+1);
- rec->length -= padding_length;
- rec->type |= padding_length<<8; /* kludge: pass padding length */
+ rec->length -= good & (padding_length+1);
return (int)((good & 1) | (~good & -1));
}
@@ -139,31 +137,23 @@ int tls1_cbc_remove_padding(const SSL* s,
unsigned mac_size)
{
unsigned padding_length, good, to_check, i;
- const char has_explicit_iv =
- s->version >= TLS1_1_VERSION || s->version == DTLS1_VERSION;
- const unsigned overhead = 1 /* padding length byte */ +
- mac_size +
- (has_explicit_iv ? block_size : 0);
-
- /* These lengths are all public so we can test them in non-constant
- * time. */
- if (overhead > rec->length)
- return 0;
-
- /* 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
- * IV, MAC and padding length byte. (These can be checked in
- * non-constant time because it's all public information.) So, if the
- * padding was invalid, then we didn't change |rec->length| and this is
- * safe. If the padding was valid then we know that we have at least
- * overhead+padding_length bytes of space and so this is still safe
- * because overhead accounts for the explicit IV. */
- if (has_explicit_iv)
+ const unsigned overhead = 1 /* padding length byte */ + mac_size;
+ /* Check if version requires explicit IV */
+ if (s->version >= TLS1_1_VERSION || s->version == DTLS1_VERSION)
{
+ /* 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];
@@ -190,7 +180,7 @@ int tls1_cbc_remove_padding(const SSL* s,
if (EVP_CIPHER_flags(s->enc_read_ctx->cipher)&EVP_CIPH_FLAG_AEAD_CIPHER)
{
/* padding is already verified */
- rec->length -= padding_length;
+ rec->length -= padding_length + 1;
return 1;
}
@@ -227,9 +217,7 @@ int tls1_cbc_remove_padding(const SSL* s,
good <<= sizeof(good)*8-1;
good = DUPLICATE_MSB_TO_ALL(good);
- padding_length = good & (padding_length+1);
- rec->length -= padding_length;
- rec->type |= padding_length<<8; /* kludge: pass padding length */
+ rec->length -= good & (padding_length+1);
return (int)((good & 1) | (~good & -1));
}
@@ -256,7 +244,7 @@ int tls1_cbc_remove_padding(const SSL* s,
*/
void ssl3_cbc_copy_mac(unsigned char* out,
const SSL3_RECORD *rec,
- unsigned md_size,unsigned orig_len)
+ unsigned md_size)
{
#if defined(CBC_MAC_ROTATE_IN_PLACE)
unsigned char rotated_mac_buf[EVP_MAX_MD_SIZE*2];
@@ -275,7 +263,7 @@ void ssl3_cbc_copy_mac(unsigned char* out,
unsigned div_spoiler;
unsigned rotate_offset;
- OPENSSL_assert(orig_len >= md_size);
+ OPENSSL_assert(rec->orig_len >= md_size);
OPENSSL_assert(md_size <= EVP_MAX_MD_SIZE);
#if defined(CBC_MAC_ROTATE_IN_PLACE)
@@ -283,8 +271,8 @@ void ssl3_cbc_copy_mac(unsigned char* out,
#endif
/* This information is public so it's safe to branch based on it. */
- if (orig_len > md_size + 255 + 1)
- scan_start = orig_len - (md_size + 255 + 1);
+ 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.
@@ -297,9 +285,9 @@ 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 < orig_len;)
+ for (i = scan_start; i < rec->orig_len;)
{
- for (j = 0; j < md_size && i < orig_len; i++, j++)
+ for (j = 0; j < md_size && i < rec->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 196f0739d5..0282ef4620 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, orig_len;
+ size_t md_size;
int npad;
int t;
@@ -755,10 +755,6 @@ 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))
@@ -790,7 +786,7 @@ int n_ssl3_mac(SSL *ssl, unsigned char *md, int send)
hash,
md, &md_size,
header, rec->input,
- rec->length + md_size, orig_len,
+ rec->length + md_size, rec->orig_len,
mac_sec, md_size,
1 /* is SSLv3 */);
}
diff --git a/ssl/s3_pkt.c b/ssl/s3_pkt.c
index 64cef2abfa..032a8558ed 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, orig_len;
+ unsigned mac_size;
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;
- orig_len=rr->length;
+ rr->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 (orig_len < mac_size ||
+ 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 &&
- orig_len < mac_size+1))
+ rr->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, orig_len);
+ ssl3_cbc_copy_mac(mac_tmp, rr, mac_size);
rr->length -= mac_size;
}
else
{
- /* In this case there's no padding, so |orig_len|
+ /* 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;
diff --git a/ssl/ssl3.h b/ssl/ssl3.h
index d2a5208824..2486011bb5 100644
--- a/ssl/ssl3.h
+++ b/ssl/ssl3.h
@@ -366,6 +366,10 @@ typedef struct ssl3_record_st
{
/*r */ int type; /* type of record */
/*rw*/ unsigned int length; /* How many bytes available */
+/*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.
+ */
/*r */ unsigned int off; /* read/write offset into 'buf' */
/*rw*/ unsigned char *data; /* pointer to the record data */
/*rw*/ unsigned char *input; /* where the decode bytes are */
diff --git a/ssl/ssl_locl.h b/ssl/ssl_locl.h
index 65c56bddc9..134198e91b 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 orig_len);
+ unsigned md_size);
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 4e23bbf77b..e313355fa2 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, orig_len;
+ size_t md_size;
int i;
EVP_MD_CTX hmac, *mac_ctx;
unsigned char header[13];
@@ -1020,10 +1020,6 @@ 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);
@@ -1042,7 +1038,7 @@ int tls1_mac(SSL *ssl, unsigned char *md, int send)
mac_ctx,
md, &md_size,
header, rec->input,
- rec->length + md_size, orig_len,
+ rec->length + md_size, rec->orig_len,
ssl->s3->read_mac_secret,
ssl->s3->read_mac_secret_size,
0 /* not SSLv3 */);
@@ -1058,7 +1054,7 @@ int tls1_mac(SSL *ssl, unsigned char *md, int send)
tls_fips_digest_extra(
ssl->enc_read_ctx,
mac_ctx, rec->input,
- rec->length, orig_len);
+ rec->length, rec->orig_len);
#endif
}
generated by cgit v1.2.3 (git 2.25.1) at 2024-09-10 16:00:25 +0000