2019-05-25 07:26:30 +00:00
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/*-
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* Copyright (c) 2014 The FreeBSD Foundation
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* Copyright (c) 2018 iXsystems, Inc
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* All rights reserved.
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*
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* This software was developed by John-Mark Gurney under
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* the sponsorship of the FreeBSD Foundation and
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* Rubicon Communications, LLC (Netgate).
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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*
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* $FreeBSD$
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*
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* This file implements AES-CCM+CBC-MAC, as described
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* at https://tools.ietf.org/html/rfc3610, using Intel's
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* AES-NI instructions.
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*
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*/
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#include <sys/types.h>
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#include <sys/endian.h>
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <crypto/aesni/aesni.h>
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#include <crypto/aesni/aesni_os.h>
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#include <crypto/aesni/aesencdec.h>
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#define AESNI_ENC(d, k, nr) aesni_enc(nr-1, (const __m128i*)k, d)
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#include <wmmintrin.h>
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#include <emmintrin.h>
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#include <smmintrin.h>
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/*
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* Encrypt a single 128-bit block after
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* doing an xor. This is also used to
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* decrypt (yay symmetric encryption).
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*/
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static inline __m128i
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xor_and_encrypt(__m128i a, __m128i b, const unsigned char *k, int nr)
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{
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2019-05-27 00:47:51 +00:00
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__m128i retval = _mm_xor_si128(a, b);
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2019-05-25 07:26:30 +00:00
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retval = AESNI_ENC(retval, k, nr);
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return (retval);
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}
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/*
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* Put value at the end of block, starting at offset.
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* (This goes backwards, putting bytes in *until* it
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* reaches offset.)
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*/
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static void
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append_int(size_t value, __m128i *block, size_t offset)
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{
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int indx = sizeof(*block) - 1;
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uint8_t *bp = (uint8_t*)block;
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while (indx > (sizeof(*block) - offset)) {
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bp[indx] = value & 0xff;
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indx--;
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value >>= 8;
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}
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}
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/*
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* Start the CBC-MAC process. This handles the auth data.
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*/
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static __m128i
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cbc_mac_start(const unsigned char *auth_data, size_t auth_len,
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const unsigned char *nonce, size_t nonce_len,
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const unsigned char *key, int nr,
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size_t data_len, size_t tag_len)
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{
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__m128i cbc_block, staging_block;
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uint8_t *byte_ptr;
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/* This defines where the message length goes */
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int L = sizeof(__m128i) - 1 - nonce_len;
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/*
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* Set up B0 here. This has the flags byte,
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* followed by the nonce, followed by the
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* length of the message.
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*/
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cbc_block = _mm_setzero_si128();
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byte_ptr = (uint8_t*)&cbc_block;
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byte_ptr[0] = ((auth_len > 0) ? 1 : 0) * 64 |
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(((tag_len - 2) / 2) * 8) |
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(L - 1);
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bcopy(nonce, byte_ptr + 1, nonce_len);
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append_int(data_len, &cbc_block, L+1);
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cbc_block = AESNI_ENC(cbc_block, key, nr);
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if (auth_len != 0) {
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/*
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* We need to start by appending the length descriptor.
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*/
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uint32_t auth_amt;
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size_t copy_amt;
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const uint8_t *auth_ptr = auth_data;
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staging_block = _mm_setzero_si128();
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/*
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* The current OCF calling convention means that
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* there can never be more than 4g of authentication
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* data, so we don't handle the 0xffff case.
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*/
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KASSERT(auth_len < (1ULL << 32),
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("%s: auth_len (%zu) larger than 4GB",
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__FUNCTION__, auth_len));
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if (auth_len < ((1 << 16) - (1 << 8))) {
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/*
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* If the auth data length is less than
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* 0xff00, we don't need to encode a length
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* specifier, just the length of the auth
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* data.
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*/
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be16enc(&staging_block, auth_len);
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auth_amt = 2;
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} else if (auth_len < (1ULL << 32)) {
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/*
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* Two bytes for the length prefix, and then
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* four bytes for the length. This makes a total
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* of 6 bytes to describe the auth data length.
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*/
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be16enc(&staging_block, 0xfffe);
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be32enc((char*)&staging_block + 2, auth_len);
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auth_amt = 6;
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} else
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panic("%s: auth len too large", __FUNCTION__);
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/*
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* Need to copy abytes into blocks. The first block is
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* already partially filled, by auth_amt, so we need
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* to handle that. The last block needs to be zero padded.
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*/
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copy_amt = MIN(auth_len - auth_amt,
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sizeof(staging_block) - auth_amt);
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byte_ptr = (uint8_t*)&staging_block;
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bcopy(auth_ptr, &byte_ptr[auth_amt], copy_amt);
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auth_ptr += copy_amt;
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cbc_block = xor_and_encrypt(cbc_block, staging_block, key, nr);
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while (auth_ptr < auth_data + auth_len) {
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copy_amt = MIN((auth_data + auth_len) - auth_ptr,
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sizeof(staging_block));
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if (copy_amt < sizeof(staging_block))
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bzero(&staging_block, sizeof(staging_block));
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bcopy(auth_ptr, &staging_block, copy_amt);
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cbc_block = xor_and_encrypt(cbc_block, staging_block,
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key, nr);
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auth_ptr += copy_amt;
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}
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}
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return (cbc_block);
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}
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/*
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* Implement AES CCM+CBC-MAC encryption and authentication.
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*
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* A couple of notes:
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* The specification allows for a different number of tag lengths;
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* however, they're always truncated from 16 bytes, and the tag
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* length isn't passed in. (This could be fixed by changing the
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* code in aesni.c:aesni_cipher_crypt().)
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* Similarly, although the nonce length is passed in, the
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* OpenCrypto API that calls us doesn't have a way to set the nonce
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* other than by having different crypto algorithm types. As a result,
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* this is currently always called with nlen=12; this means that we
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* also have a maximum message length of 16 megabytes. And similarly,
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* since abytes is limited to a 32 bit value here, the AAD is
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* limited to 4 gigabytes or less.
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*/
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void
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AES_CCM_encrypt(const unsigned char *in, unsigned char *out,
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const unsigned char *addt, const unsigned char *nonce,
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unsigned char *tag, uint32_t nbytes, uint32_t abytes, int nlen,
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const unsigned char *key, int nr)
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{
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static const int tag_length = 16; /* 128 bits */
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int L;
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int counter = 1; /* S0 has 0, S1 has 1 */
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size_t copy_amt, total = 0;
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uint8_t *byte_ptr;
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__m128i s0, rolling_mac, s_x, staging_block;
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if (nbytes == 0 && abytes == 0)
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return;
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/* NIST 800-38c section A.1 says n is [7, 13]. */
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if (nlen < 7 || nlen > 13)
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panic("%s: bad nonce length %d", __FUNCTION__, nlen);
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/*
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* We need to know how many bytes to use to describe
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* the length of the data. Normally, nlen should be
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* 12, which leaves us 3 bytes to do that -- 16mbytes of
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* data to encrypt. But it can be longer or shorter;
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* this impacts the length of the message.
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*/
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L = sizeof(__m128i) - 1 - nlen;
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/*
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* Now, this shouldn't happen, but let's make sure that
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* the data length isn't too big.
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*/
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KASSERT(nbytes <= ((1 << (8 * L)) - 1),
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("%s: nbytes is %u, but length field is %d bytes",
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__FUNCTION__, nbytes, L));
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/*
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* Clear out the blocks
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*/
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s0 = _mm_setzero_si128();
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rolling_mac = cbc_mac_start(addt, abytes, nonce, nlen,
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key, nr, nbytes, tag_length);
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/* s0 has flags, nonce, and then 0 */
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byte_ptr = (uint8_t*)&s0;
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byte_ptr[0] = L - 1; /* but the flags byte only has L' */
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bcopy(nonce, &byte_ptr[1], nlen);
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/*
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* Now to cycle through the rest of the data.
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*/
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bcopy(&s0, &s_x, sizeof(s0));
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while (total < nbytes) {
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/*
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* Copy the plain-text data into staging_block.
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* This may need to be zero-padded.
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*/
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copy_amt = MIN(nbytes - total, sizeof(staging_block));
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bcopy(in+total, &staging_block, copy_amt);
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if (copy_amt < sizeof(staging_block)) {
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byte_ptr = (uint8_t*)&staging_block;
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bzero(&byte_ptr[copy_amt],
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sizeof(staging_block) - copy_amt);
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}
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rolling_mac = xor_and_encrypt(rolling_mac, staging_block,
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key, nr);
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/* Put the counter into the s_x block */
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append_int(counter++, &s_x, L+1);
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/* Encrypt that */
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__m128i X = AESNI_ENC(s_x, key, nr);
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/* XOR the plain-text with the encrypted counter block */
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staging_block = _mm_xor_si128(staging_block, X);
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/* And copy it out */
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bcopy(&staging_block, out+total, copy_amt);
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total += copy_amt;
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}
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/*
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* Allegedly done with it! Except for the tag.
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*/
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s0 = AESNI_ENC(s0, key, nr);
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staging_block = _mm_xor_si128(s0, rolling_mac);
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bcopy(&staging_block, tag, tag_length);
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explicit_bzero(&s0, sizeof(s0));
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explicit_bzero(&staging_block, sizeof(staging_block));
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explicit_bzero(&s_x, sizeof(s_x));
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explicit_bzero(&rolling_mac, sizeof(rolling_mac));
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}
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/*
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* Implement AES CCM+CBC-MAC decryption and authentication.
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* Returns 0 on failure, 1 on success.
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*
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* The primary difference here is that each encrypted block
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* needs to be hashed&encrypted after it is decrypted (since
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* the CBC-MAC is based on the plain text). This means that
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* we do the decryption twice -- first to verify the tag,
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* and second to decrypt and copy it out.
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*
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* To avoid annoying code copying, we implement the main
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* loop as a separate function.
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*
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* Call with out as NULL to not store the decrypted results;
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* call with hashp as NULL to not run the authentication.
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* Calling with neither as NULL does the decryption and
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* authentication as a single pass (which is not allowed
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* per the specification, really).
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*
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* If hashp is non-NULL, it points to the post-AAD computed
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* checksum.
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*/
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static void
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decrypt_loop(const unsigned char *in, unsigned char *out, size_t nbytes,
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__m128i s0, size_t nonce_length, __m128i *macp,
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const unsigned char *key, int nr)
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{
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size_t total = 0;
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__m128i s_x = s0, mac_block;
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int counter = 1;
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const size_t L = sizeof(__m128i) - 1 - nonce_length;
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__m128i pad_block, staging_block;
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/*
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* The starting mac (post AAD, if any).
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*/
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if (macp != NULL)
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mac_block = *macp;
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while (total < nbytes) {
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size_t copy_amt = MIN(nbytes - total, sizeof(staging_block));
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if (copy_amt < sizeof(staging_block)) {
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staging_block = _mm_setzero_si128();
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}
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bcopy(in+total, &staging_block, copy_amt);
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/*
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* staging_block has the current block of input data,
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* zero-padded if necessary. This is used in computing
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* both the decrypted data, and the authentication tag.
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*/
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append_int(counter++, &s_x, L+1);
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/*
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* The tag is computed based on the decrypted data.
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*/
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pad_block = AESNI_ENC(s_x, key, nr);
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if (copy_amt < sizeof(staging_block)) {
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/*
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* Need to pad out pad_block with 0.
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* (staging_block was set to 0's above.)
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*/
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uint8_t *end_of_buffer = (uint8_t*)&pad_block;
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bzero(end_of_buffer + copy_amt,
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sizeof(pad_block) - copy_amt);
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}
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|
|
|
staging_block = _mm_xor_si128(staging_block, pad_block);
|
|
|
|
|
|
|
|
if (out)
|
|
|
|
bcopy(&staging_block, out+total, copy_amt);
|
|
|
|
|
|
|
|
if (macp)
|
|
|
|
mac_block = xor_and_encrypt(mac_block, staging_block,
|
|
|
|
key, nr);
|
|
|
|
total += copy_amt;
|
|
|
|
}
|
|
|
|
|
|
|
|
if (macp)
|
|
|
|
*macp = mac_block;
|
|
|
|
|
|
|
|
explicit_bzero(&pad_block, sizeof(pad_block));
|
|
|
|
explicit_bzero(&staging_block, sizeof(staging_block));
|
|
|
|
explicit_bzero(&mac_block, sizeof(mac_block));
|
|
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
|
|
* The exposed decryption routine. This is practically a
|
|
|
|
* copy of the encryption routine, except that the order
|
|
|
|
* in which the tag is created is changed.
|
|
|
|
* XXX combine the two functions at some point!
|
|
|
|
*/
|
|
|
|
int
|
|
|
|
AES_CCM_decrypt(const unsigned char *in, unsigned char *out,
|
|
|
|
const unsigned char *addt, const unsigned char *nonce,
|
|
|
|
const unsigned char *tag, uint32_t nbytes, uint32_t abytes, int nlen,
|
|
|
|
const unsigned char *key, int nr)
|
|
|
|
{
|
|
|
|
static const int tag_length = 16; /* 128 bits */
|
|
|
|
int L;
|
|
|
|
__m128i s0, rolling_mac, staging_block;
|
|
|
|
uint8_t *byte_ptr;
|
|
|
|
|
|
|
|
if (nbytes == 0 && abytes == 0)
|
|
|
|
return (1); // No message means no decryption!
|
|
|
|
if (nlen < 0 || nlen > 15)
|
|
|
|
panic("%s: bad nonce length %d", __FUNCTION__, nlen);
|
|
|
|
|
|
|
|
/*
|
|
|
|
* We need to know how many bytes to use to describe
|
|
|
|
* the length of the data. Normally, nlen should be
|
|
|
|
* 12, which leaves us 3 bytes to do that -- 16mbytes of
|
|
|
|
* data to encrypt. But it can be longer or shorter.
|
|
|
|
*/
|
|
|
|
L = sizeof(__m128i) - 1 - nlen;
|
|
|
|
|
|
|
|
/*
|
|
|
|
* Now, this shouldn't happen, but let's make sure that
|
|
|
|
* the data length isn't too big.
|
|
|
|
*/
|
|
|
|
if (nbytes > ((1 << (8 * L)) - 1))
|
|
|
|
panic("%s: nbytes is %u, but length field is %d bytes",
|
|
|
|
__FUNCTION__, nbytes, L);
|
|
|
|
/*
|
|
|
|
* Clear out the blocks
|
|
|
|
*/
|
|
|
|
s0 = _mm_setzero_si128();
|
|
|
|
|
|
|
|
rolling_mac = cbc_mac_start(addt, abytes, nonce, nlen,
|
|
|
|
key, nr, nbytes, tag_length);
|
|
|
|
/* s0 has flags, nonce, and then 0 */
|
|
|
|
byte_ptr = (uint8_t*)&s0;
|
|
|
|
byte_ptr[0] = L-1; /* but the flags byte only has L' */
|
|
|
|
bcopy(nonce, &byte_ptr[1], nlen);
|
|
|
|
|
|
|
|
/*
|
|
|
|
* Now to cycle through the rest of the data.
|
|
|
|
*/
|
|
|
|
decrypt_loop(in, NULL, nbytes, s0, nlen, &rolling_mac, key, nr);
|
|
|
|
|
|
|
|
/*
|
|
|
|
* Compare the tag.
|
|
|
|
*/
|
|
|
|
staging_block = _mm_xor_si128(AESNI_ENC(s0, key, nr), rolling_mac);
|
|
|
|
if (timingsafe_bcmp(&staging_block, tag, tag_length) != 0) {
|
|
|
|
return (0);
|
|
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
|
|
* Push out the decryption results this time.
|
|
|
|
*/
|
|
|
|
decrypt_loop(in, out, nbytes, s0, nlen, NULL, key, nr);
|
|
|
|
return (1);
|
|
|
|
}
|