diff options
| -rw-r--r-- | src/ssl/rec_read.cpp | 14 |
1 files changed, 10 insertions, 4 deletions
diff --git a/src/ssl/rec_read.cpp b/src/ssl/rec_read.cpp index 4f030cf1e..8f8e5dc1e 100644 --- a/src/ssl/rec_read.cpp +++ b/src/ssl/rec_read.cpp @@ -163,18 +163,24 @@ u32bit Record_Reader::get_record(byte& msg_type, byte pad_value = plaintext[plaintext.size()-1]; pad_size = pad_value + 1; + /* + * Check the padding; if it is wrong, then say we have 0 bytes of + * padding, which should ensure that the MAC check below does not + * suceed. This hides a timing channel. + * + * This particular countermeasure is recommended in the TLS 1.2 + * spec (RFC 5246) in section 6.2.3.2 + */ if(version == SSL_V3) { if(pad_value > block_size) - throw TLS_Exception(BAD_RECORD_MAC, - "Record_Reader: Bad padding"); + pad_size = 0; } else { for(u32bit j = 0; j != pad_size; j++) if(plaintext[plaintext.size()-j-1] != pad_value) - throw TLS_Exception(BAD_RECORD_MAC, - "Record_Reader: Bad padding"); + pad_size = 0; } } |