s->s3->tmp.key_block_length=0;
}
+/* ssl3_enc encrypts/decrypts the record in |s->wrec| / |s->rrec|, respectively.
+ *
+ * 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
+ * occured.
+ */
int ssl3_enc(SSL *s, int send)
{
SSL3_RECORD *rec;
EVP_CIPHER_CTX *ds;
unsigned long l;
- int bs,i;
+ int bs,i,mac_size=0;
const EVP_CIPHER *enc;
if (send)
if (!send)
{
if (l == 0 || l%bs != 0)
- {
- SSLerr(SSL_F_SSL3_ENC,SSL_R_BLOCK_CIPHER_PAD_IS_WRONG);
- ssl3_send_alert(s,SSL3_AL_FATAL,SSL_AD_DECRYPTION_FAILED);
return 0;
- }
/* otherwise, rec->length >= bs */
}
EVP_Cipher(ds,rec->data,rec->input,l);
+ if (s->read_hash != NULL)
+ mac_size = EVP_MD_size(s->read_hash);
+
if ((bs != 1) && !send)
- {
- i=rec->data[l-1]+1;
- /* SSL 3.0 bounds the number of padding bytes by the block size;
- * padding bytes (except the last one) are arbitrary */
- if (i > bs)
- {
- /* Incorrect padding. SSLerr() and ssl3_alert are done
- * by caller: we don't want to reveal whether this is
- * a decryption error or a MAC verification failure
- * (see http://www.openssl.org/~bodo/tls-cbc.txt) */
- return -1;
- }
- /* now i <= bs <= rec->length */
- rec->length-=i;
- }
+ return ssl3_cbc_remove_padding(s, rec, bs, mac_size);
}
return(1);
}
EVP_MD_CTX md_ctx;
const EVP_MD *hash;
unsigned char *p,rec_char;
- unsigned int md_size;
+ size_t md_size, orig_len;
int npad;
if (send)
md_size=EVP_MD_size(hash);
npad=(48/md_size)*md_size;
- /* Chop the digest off the end :-) */
- EVP_MD_CTX_init(&md_ctx);
-
- EVP_DigestInit_ex( &md_ctx,hash, NULL);
- EVP_DigestUpdate(&md_ctx,mac_sec,md_size);
- EVP_DigestUpdate(&md_ctx,ssl3_pad_1,npad);
- EVP_DigestUpdate(&md_ctx,seq,8);
- rec_char=rec->type;
- EVP_DigestUpdate(&md_ctx,&rec_char,1);
- p=md;
- s2n(rec->length,p);
- EVP_DigestUpdate(&md_ctx,md,2);
- EVP_DigestUpdate(&md_ctx,rec->input,rec->length);
- EVP_DigestFinal_ex( &md_ctx,md,NULL);
-
- EVP_DigestInit_ex( &md_ctx,hash, NULL);
- EVP_DigestUpdate(&md_ctx,mac_sec,md_size);
- EVP_DigestUpdate(&md_ctx,ssl3_pad_2,npad);
- EVP_DigestUpdate(&md_ctx,md,md_size);
- EVP_DigestFinal_ex( &md_ctx,md,&md_size);
-
- EVP_MD_CTX_cleanup(&md_ctx);
+ /* 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))
+ {
+ /* 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;
+
+ ssl3_cbc_digest_record(
+ hash,
+ md, &md_size,
+ header, rec->input,
+ rec->length + md_size, orig_len,
+ mac_sec, md_size,
+ 1 /* is SSLv3 */);
+ }
+ else
+ {
+ unsigned int md_size_u;
+ /* Chop the digest off the end :-) */
+ EVP_MD_CTX_init(&md_ctx);
+
+ EVP_DigestInit_ex( &md_ctx,hash, NULL);
+ EVP_DigestUpdate(&md_ctx,mac_sec,md_size);
+ EVP_DigestUpdate(&md_ctx,ssl3_pad_1,npad);
+ EVP_DigestUpdate(&md_ctx,seq,8);
+ rec_char=rec->type;
+ EVP_DigestUpdate(&md_ctx,&rec_char,1);
+ p=md;
+ s2n(rec->length,p);
+ EVP_DigestUpdate(&md_ctx,md,2);
+ EVP_DigestUpdate(&md_ctx,rec->input,rec->length);
+ EVP_DigestFinal_ex( &md_ctx,md,NULL);
+
+ EVP_DigestInit_ex( &md_ctx,hash, NULL);
+ EVP_DigestUpdate(&md_ctx,mac_sec,md_size);
+ EVP_DigestUpdate(&md_ctx,ssl3_pad_2,npad);
+ EVP_DigestUpdate(&md_ctx,md,md_size);
+ EVP_DigestFinal_ex( &md_ctx,md,&md_size_u);
+ md_size = md_size_u;
+
+ EVP_MD_CTX_cleanup(&md_ctx);
+ }
ssl3_record_sequence_update(seq);
return(md_size);
projects / openssl.git / blobdiff