Differential D19298 Diff 57884 head/sys/crypto/aesni/aesni_ccm.c

Changeset View

Standalone View

head/sys/crypto/aesni/aesni_ccm.c

Property	Old Value	New Value
svn:eol-style	null	native \ No newline at end of property
svn:keywords	null	FreeBSD=%H \ No newline at end of property
svn:mime-type	null	text/plain \ No newline at end of property

				/*-
				* Copyright (c) 2014 The FreeBSD Foundation
				* Copyright (c) 2018 iXsystems, Inc
				* All rights reserved.
				*
				* This software was developed by John-Mark Gurney under
				* the sponsorship of the FreeBSD Foundation and
				* Rubicon Communications, LLC (Netgate).
				* Redistribution and use in source and binary forms, with or without
				* modification, are permitted provided that the following conditions
				* are met:
				* 1. Redistributions of source code must retain the above copyright
				* notice, this list of conditions and the following disclaimer.
				* 2. Redistributions in binary form must reproduce the above copyright
				* notice, this list of conditions and the following disclaimer in the
				* documentation and/or other materials provided with the distribution.
				*
				* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
				* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
				* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
				* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
				* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
				* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
				* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
				* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
				* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
				* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
				* SUCH DAMAGE.
				*
				*
				* $FreeBSD$
				*
				* This file implements AES-CCM+CBC-MAC, as described
				* at https://tools.ietf.org/html/rfc3610, using Intel's
				* AES-NI instructions.
				*
				*/

				#include <sys/types.h>
				#include <sys/endian.h>
				#include <sys/param.h>

				#include <sys/systm.h>
				#include <crypto/aesni/aesni.h>
				#include <crypto/aesni/aesni_os.h>
				#include <crypto/aesni/aesencdec.h>
				#define AESNI_ENC(d, k, nr) aesni_enc(nr-1, (const __m128i*)k, d)

				#include <wmmintrin.h>
				#include <emmintrin.h>
				#include <smmintrin.h>

				/*
				* Encrypt a single 128-bit block after
				* doing an xor. This is also used to
				* decrypt (yay symmetric encryption).
				*/
				static inline __m128i
				xor_and_encrypt(__m128i a, __m128i b, const unsigned char *k, int nr)
				{
				__m128 retval = _mm_xor_si128(a, b);

				retval = AESNI_ENC(retval, k, nr);
				return (retval);
				}

				/*
				* Put value at the end of block, starting at offset.
				* (This goes backwards, putting bytes in until it
				* reaches offset.)
				*/
				static void
				append_int(size_t value, __m128i *block, size_t offset)
				{
				int indx = sizeof(*block) - 1;
				uint8_t bp = (uint8_t)block;

				while (indx > (sizeof(*block) - offset)) {
				bp[indx] = value & 0xff;
				indx--;
				value >>= 8;
				}
				}

				/*
				* Start the CBC-MAC process. This handles the auth data.
				*/
				static __m128i
				cbc_mac_start(const unsigned char *auth_data, size_t auth_len,
				const unsigned char *nonce, size_t nonce_len,
				const unsigned char *key, int nr,
				size_t data_len, size_t tag_len)
				{
				__m128i cbc_block, staging_block;
				uint8_t *byte_ptr;
				/* This defines where the message length goes */
				int L = sizeof(__m128i) - 1 - nonce_len;

				/*
				* Set up B0 here. This has the flags byte,
				* followed by the nonce, followed by the
				* length of the message.
				*/
				cbc_block = _mm_setzero_si128();
				byte_ptr = (uint8_t*)&cbc_block;
				byte_ptr[0] = ((auth_len > 0) ? 1 : 0) * 64 \|
				(((tag_len - 2) / 2) * 8) \|
				(L - 1);
				bcopy(nonce, byte_ptr + 1, nonce_len);
				append_int(data_len, &cbc_block, L+1);
				cbc_block = AESNI_ENC(cbc_block, key, nr);

				if (auth_len != 0) {
				/*
				* We need to start by appending the length descriptor.
				*/
				uint32_t auth_amt;
				size_t copy_amt;
				const uint8_t *auth_ptr = auth_data;

				staging_block = _mm_setzero_si128();

				/*
				* The current OCF calling convention means that
				* there can never be more than 4g of authentication
				* data, so we don't handle the 0xffff case.
				*/
				KASSERT(auth_len < (1ULL << 32),
				("%s: auth_len (%zu) larger than 4GB",
				__FUNCTION__, auth_len));

				if (auth_len < ((1 << 16) - (1 << 8))) {
				/*
				* If the auth data length is less than
				* 0xff00, we don't need to encode a length
				* specifier, just the length of the auth
				* data.
				*/
				be16enc(&staging_block, auth_len);
				auth_amt = 2;
				} else if (auth_len < (1ULL << 32)) {
				/*
				* Two bytes for the length prefix, and then
				* four bytes for the length. This makes a total
				* of 6 bytes to describe the auth data length.
				*/
				be16enc(&staging_block, 0xfffe);
				be32enc((char*)&staging_block + 2, auth_len);
				auth_amt = 6;
				} else
				panic("%s: auth len too large", __FUNCTION__);

				/*
				* Need to copy abytes into blocks. The first block is
				* already partially filled, by auth_amt, so we need
				* to handle that. The last block needs to be zero padded.
				*/
				copy_amt = MIN(auth_len - auth_amt,
				sizeof(staging_block) - auth_amt);
				byte_ptr = (uint8_t*)&staging_block;
				bcopy(auth_ptr, &byte_ptr[auth_amt], copy_amt);
				auth_ptr += copy_amt;

				cbc_block = xor_and_encrypt(cbc_block, staging_block, key, nr);

				while (auth_ptr < auth_data + auth_len) {
				copy_amt = MIN((auth_data + auth_len) - auth_ptr,
				sizeof(staging_block));
				if (copy_amt < sizeof(staging_block))
				bzero(&staging_block, sizeof(staging_block));
				bcopy(auth_ptr, &staging_block, copy_amt);
				cbc_block = xor_and_encrypt(cbc_block, staging_block,
				key, nr);
				auth_ptr += copy_amt;
				}
				}
				return (cbc_block);
				}

				/*
				* Implement AES CCM+CBC-MAC encryption and authentication.
				*
				* A couple of notes:
				* The specification allows for a different number of tag lengths;
				* however, they're always truncated from 16 bytes, and the tag
				* length isn't passed in. (This could be fixed by changing the
				* code in aesni.c:aesni_cipher_crypt().)
				* Similarly, although the nonce length is passed in, the
				* OpenCrypto API that calls us doesn't have a way to set the nonce
				* other than by having different crypto algorithm types. As a result,
				* this is currently always called with nlen=12; this means that we
				* also have a maximum message length of 16 megabytes. And similarly,
				* since abytes is limited to a 32 bit value here, the AAD is
				* limited to 4 gigabytes or less.
				*/
				void
				AES_CCM_encrypt(const unsigned char in, unsigned char out,
				const unsigned char addt, const unsigned char nonce,
				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;
				int counter = 1; /* S0 has 0, S1 has 1 */
				size_t copy_amt, total = 0;
				uint8_t *byte_ptr;
				__m128i s0, rolling_mac, s_x, staging_block;

				if (nbytes == 0 && abytes == 0)
				return;

				/* NIST 800-38c section A.1 says n is [7, 13]. */
				if (nlen < 7 \|\| nlen > 13)
				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;
				* this impacts the length of the message.
				*/
				L = sizeof(__m128i) - 1 - nlen;

				/*
				* Now, this shouldn't happen, but let's make sure that
				* the data length isn't too big.
				*/
				KASSERT(nbytes <= ((1 << (8 * L)) - 1),
				("%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.
				*/
				bcopy(&s0, &s_x, sizeof(s0));

				while (total < nbytes) {
				/*
				* Copy the plain-text data into staging_block.
				* This may need to be zero-padded.
				*/
				copy_amt = MIN(nbytes - total, sizeof(staging_block));
				bcopy(in+total, &staging_block, copy_amt);
				if (copy_amt < sizeof(staging_block)) {
				byte_ptr = (uint8_t*)&staging_block;
				bzero(&byte_ptr[copy_amt],
				sizeof(staging_block) - copy_amt);
				}
				rolling_mac = xor_and_encrypt(rolling_mac, staging_block,
				key, nr);
				/* Put the counter into the s_x block */
				append_int(counter++, &s_x, L+1);
				/* Encrypt that */
				__m128i X = AESNI_ENC(s_x, key, nr);
				/* XOR the plain-text with the encrypted counter block */
				staging_block = _mm_xor_si128(staging_block, X);
				/* And copy it out */
				bcopy(&staging_block, out+total, copy_amt);
				total += copy_amt;
				}
				/*
				* Allegedly done with it! Except for the tag.
				*/
				s0 = AESNI_ENC(s0, key, nr);
				staging_block = _mm_xor_si128(s0, rolling_mac);
				bcopy(&staging_block, tag, tag_length);
				explicit_bzero(&s0, sizeof(s0));
				explicit_bzero(&staging_block, sizeof(staging_block));
				explicit_bzero(&s_x, sizeof(s_x));
				explicit_bzero(&rolling_mac, sizeof(rolling_mac));
				}

				/*
				* Implement AES CCM+CBC-MAC decryption and authentication.
				* Returns 0 on failure, 1 on success.
				*
				* The primary difference here is that each encrypted block
				* needs to be hashed&encrypted after it is decrypted (since
				* the CBC-MAC is based on the plain text). This means that
				* we do the decryption twice -- first to verify the tag,
				* and second to decrypt and copy it out.
				*
				* To avoid annoying code copying, we implement the main
				* loop as a separate function.
				*
				* Call with out as NULL to not store the decrypted results;
				* call with hashp as NULL to not run the authentication.
				* Calling with neither as NULL does the decryption and
				* authentication as a single pass (which is not allowed
				* per the specification, really).
				*
				* If hashp is non-NULL, it points to the post-AAD computed
				* checksum.
				*/
				static void
				decrypt_loop(const unsigned char in, unsigned char out, size_t nbytes,
				__m128i s0, size_t nonce_length, __m128i *macp,
				const unsigned char *key, int nr)
				{
				size_t total = 0;
				__m128i s_x = s0, mac_block;
				int counter = 1;
				const size_t L = sizeof(__m128i) - 1 - nonce_length;
				__m128i pad_block, staging_block;

				/*
				* The starting mac (post AAD, if any).
				*/
				if (macp != NULL)
				mac_block = *macp;

				while (total < nbytes) {
				size_t copy_amt = MIN(nbytes - total, sizeof(staging_block));

				if (copy_amt < sizeof(staging_block)) {
				staging_block = _mm_setzero_si128();
				}
				bcopy(in+total, &staging_block, copy_amt);

				/*
				* staging_block has the current block of input data,
				* zero-padded if necessary. This is used in computing
				* both the decrypted data, and the authentication tag.
				*/
				append_int(counter++, &s_x, L+1);
				/*
				* The tag is computed based on the decrypted data.
				*/
				pad_block = AESNI_ENC(s_x, key, nr);
				if (copy_amt < sizeof(staging_block)) {
				/*
				* Need to pad out pad_block with 0.
				* (staging_block was set to 0's above.)
				*/
				uint8_t end_of_buffer = (uint8_t)&pad_block;
				bzero(end_of_buffer + copy_amt,
				sizeof(pad_block) - copy_amt);
				}
				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);
				}