linux/drivers/crypto/nx/nx-aes-ccm.c
David Gstir cb8affb55c crypto: nx - Fix timing leak in GCM and CCM decryption
Using non-constant time memcmp() makes the verification of the authentication
tag in the decrypt path vulnerable to timing attacks. Fix this by using
crypto_memneq() instead.

Cc: stable@vger.kernel.org
Signed-off-by: David Gstir <david@sigma-star.at>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2015-11-16 21:39:23 +08:00

596 lines
15 KiB
C

/**
* AES CCM routines supporting the Power 7+ Nest Accelerators driver
*
* Copyright (C) 2012 International Business Machines Inc.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; version 2 only.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*
* Author: Kent Yoder <yoder1@us.ibm.com>
*/
#include <crypto/internal/aead.h>
#include <crypto/aes.h>
#include <crypto/algapi.h>
#include <crypto/scatterwalk.h>
#include <linux/module.h>
#include <linux/types.h>
#include <linux/crypto.h>
#include <asm/vio.h>
#include "nx_csbcpb.h"
#include "nx.h"
static int ccm_aes_nx_set_key(struct crypto_aead *tfm,
const u8 *in_key,
unsigned int key_len)
{
struct nx_crypto_ctx *nx_ctx = crypto_tfm_ctx(&tfm->base);
struct nx_csbcpb *csbcpb = nx_ctx->csbcpb;
struct nx_csbcpb *csbcpb_aead = nx_ctx->csbcpb_aead;
nx_ctx_init(nx_ctx, HCOP_FC_AES);
switch (key_len) {
case AES_KEYSIZE_128:
NX_CPB_SET_KEY_SIZE(csbcpb, NX_KS_AES_128);
NX_CPB_SET_KEY_SIZE(csbcpb_aead, NX_KS_AES_128);
nx_ctx->ap = &nx_ctx->props[NX_PROPS_AES_128];
break;
default:
return -EINVAL;
}
csbcpb->cpb.hdr.mode = NX_MODE_AES_CCM;
memcpy(csbcpb->cpb.aes_ccm.key, in_key, key_len);
csbcpb_aead->cpb.hdr.mode = NX_MODE_AES_CCA;
memcpy(csbcpb_aead->cpb.aes_cca.key, in_key, key_len);
return 0;
}
static int ccm4309_aes_nx_set_key(struct crypto_aead *tfm,
const u8 *in_key,
unsigned int key_len)
{
struct nx_crypto_ctx *nx_ctx = crypto_tfm_ctx(&tfm->base);
if (key_len < 3)
return -EINVAL;
key_len -= 3;
memcpy(nx_ctx->priv.ccm.nonce, in_key + key_len, 3);
return ccm_aes_nx_set_key(tfm, in_key, key_len);
}
static int ccm_aes_nx_setauthsize(struct crypto_aead *tfm,
unsigned int authsize)
{
switch (authsize) {
case 4:
case 6:
case 8:
case 10:
case 12:
case 14:
case 16:
break;
default:
return -EINVAL;
}
return 0;
}
static int ccm4309_aes_nx_setauthsize(struct crypto_aead *tfm,
unsigned int authsize)
{
switch (authsize) {
case 8:
case 12:
case 16:
break;
default:
return -EINVAL;
}
return 0;
}
/* taken from crypto/ccm.c */
static int set_msg_len(u8 *block, unsigned int msglen, int csize)
{
__be32 data;
memset(block, 0, csize);
block += csize;
if (csize >= 4)
csize = 4;
else if (msglen > (unsigned int)(1 << (8 * csize)))
return -EOVERFLOW;
data = cpu_to_be32(msglen);
memcpy(block - csize, (u8 *)&data + 4 - csize, csize);
return 0;
}
/* taken from crypto/ccm.c */
static inline int crypto_ccm_check_iv(const u8 *iv)
{
/* 2 <= L <= 8, so 1 <= L' <= 7. */
if (1 > iv[0] || iv[0] > 7)
return -EINVAL;
return 0;
}
/* based on code from crypto/ccm.c */
static int generate_b0(u8 *iv, unsigned int assoclen, unsigned int authsize,
unsigned int cryptlen, u8 *b0)
{
unsigned int l, lp, m = authsize;
int rc;
memcpy(b0, iv, 16);
lp = b0[0];
l = lp + 1;
/* set m, bits 3-5 */
*b0 |= (8 * ((m - 2) / 2));
/* set adata, bit 6, if associated data is used */
if (assoclen)
*b0 |= 64;
rc = set_msg_len(b0 + 16 - l, cryptlen, l);
return rc;
}
static int generate_pat(u8 *iv,
struct aead_request *req,
struct nx_crypto_ctx *nx_ctx,
unsigned int authsize,
unsigned int nbytes,
unsigned int assoclen,
u8 *out)
{
struct nx_sg *nx_insg = nx_ctx->in_sg;
struct nx_sg *nx_outsg = nx_ctx->out_sg;
unsigned int iauth_len = 0;
u8 tmp[16], *b1 = NULL, *b0 = NULL, *result = NULL;
int rc;
unsigned int max_sg_len;
/* zero the ctr value */
memset(iv + 15 - iv[0], 0, iv[0] + 1);
/* page 78 of nx_wb.pdf has,
* Note: RFC3610 allows the AAD data to be up to 2^64 -1 bytes
* in length. If a full message is used, the AES CCA implementation
* restricts the maximum AAD length to 2^32 -1 bytes.
* If partial messages are used, the implementation supports
* 2^64 -1 bytes maximum AAD length.
*
* However, in the cryptoapi's aead_request structure,
* assoclen is an unsigned int, thus it cannot hold a length
* value greater than 2^32 - 1.
* Thus the AAD is further constrained by this and is never
* greater than 2^32.
*/
if (!assoclen) {
b0 = nx_ctx->csbcpb->cpb.aes_ccm.in_pat_or_b0;
} else if (assoclen <= 14) {
/* if associated data is 14 bytes or less, we do 1 GCM
* operation on 2 AES blocks, B0 (stored in the csbcpb) and B1,
* which is fed in through the source buffers here */
b0 = nx_ctx->csbcpb->cpb.aes_ccm.in_pat_or_b0;
b1 = nx_ctx->priv.ccm.iauth_tag;
iauth_len = assoclen;
} else if (assoclen <= 65280) {
/* if associated data is less than (2^16 - 2^8), we construct
* B1 differently and feed in the associated data to a CCA
* operation */
b0 = nx_ctx->csbcpb_aead->cpb.aes_cca.b0;
b1 = nx_ctx->csbcpb_aead->cpb.aes_cca.b1;
iauth_len = 14;
} else {
b0 = nx_ctx->csbcpb_aead->cpb.aes_cca.b0;
b1 = nx_ctx->csbcpb_aead->cpb.aes_cca.b1;
iauth_len = 10;
}
/* generate B0 */
rc = generate_b0(iv, assoclen, authsize, nbytes, b0);
if (rc)
return rc;
/* generate B1:
* add control info for associated data
* RFC 3610 and NIST Special Publication 800-38C
*/
if (b1) {
memset(b1, 0, 16);
if (assoclen <= 65280) {
*(u16 *)b1 = assoclen;
scatterwalk_map_and_copy(b1 + 2, req->src, 0,
iauth_len, SCATTERWALK_FROM_SG);
} else {
*(u16 *)b1 = (u16)(0xfffe);
*(u32 *)&b1[2] = assoclen;
scatterwalk_map_and_copy(b1 + 6, req->src, 0,
iauth_len, SCATTERWALK_FROM_SG);
}
}
/* now copy any remaining AAD to scatterlist and call nx... */
if (!assoclen) {
return rc;
} else if (assoclen <= 14) {
unsigned int len = 16;
nx_insg = nx_build_sg_list(nx_insg, b1, &len, nx_ctx->ap->sglen);
if (len != 16)
return -EINVAL;
nx_outsg = nx_build_sg_list(nx_outsg, tmp, &len,
nx_ctx->ap->sglen);
if (len != 16)
return -EINVAL;
/* inlen should be negative, indicating to phyp that its a
* pointer to an sg list */
nx_ctx->op.inlen = (nx_ctx->in_sg - nx_insg) *
sizeof(struct nx_sg);
nx_ctx->op.outlen = (nx_ctx->out_sg - nx_outsg) *
sizeof(struct nx_sg);
NX_CPB_FDM(nx_ctx->csbcpb) |= NX_FDM_ENDE_ENCRYPT;
NX_CPB_FDM(nx_ctx->csbcpb) |= NX_FDM_INTERMEDIATE;
result = nx_ctx->csbcpb->cpb.aes_ccm.out_pat_or_mac;
rc = nx_hcall_sync(nx_ctx, &nx_ctx->op,
req->base.flags & CRYPTO_TFM_REQ_MAY_SLEEP);
if (rc)
return rc;
atomic_inc(&(nx_ctx->stats->aes_ops));
atomic64_add(assoclen, &nx_ctx->stats->aes_bytes);
} else {
unsigned int processed = 0, to_process;
processed += iauth_len;
/* page_limit: number of sg entries that fit on one page */
max_sg_len = min_t(u64, nx_ctx->ap->sglen,
nx_driver.of.max_sg_len/sizeof(struct nx_sg));
max_sg_len = min_t(u64, max_sg_len,
nx_ctx->ap->databytelen/NX_PAGE_SIZE);
do {
to_process = min_t(u32, assoclen - processed,
nx_ctx->ap->databytelen);
nx_insg = nx_walk_and_build(nx_ctx->in_sg,
nx_ctx->ap->sglen,
req->src, processed,
&to_process);
if ((to_process + processed) < assoclen) {
NX_CPB_FDM(nx_ctx->csbcpb_aead) |=
NX_FDM_INTERMEDIATE;
} else {
NX_CPB_FDM(nx_ctx->csbcpb_aead) &=
~NX_FDM_INTERMEDIATE;
}
nx_ctx->op_aead.inlen = (nx_ctx->in_sg - nx_insg) *
sizeof(struct nx_sg);
result = nx_ctx->csbcpb_aead->cpb.aes_cca.out_pat_or_b0;
rc = nx_hcall_sync(nx_ctx, &nx_ctx->op_aead,
req->base.flags & CRYPTO_TFM_REQ_MAY_SLEEP);
if (rc)
return rc;
memcpy(nx_ctx->csbcpb_aead->cpb.aes_cca.b0,
nx_ctx->csbcpb_aead->cpb.aes_cca.out_pat_or_b0,
AES_BLOCK_SIZE);
NX_CPB_FDM(nx_ctx->csbcpb_aead) |= NX_FDM_CONTINUATION;
atomic_inc(&(nx_ctx->stats->aes_ops));
atomic64_add(assoclen, &nx_ctx->stats->aes_bytes);
processed += to_process;
} while (processed < assoclen);
result = nx_ctx->csbcpb_aead->cpb.aes_cca.out_pat_or_b0;
}
memcpy(out, result, AES_BLOCK_SIZE);
return rc;
}
static int ccm_nx_decrypt(struct aead_request *req,
struct blkcipher_desc *desc,
unsigned int assoclen)
{
struct nx_crypto_ctx *nx_ctx = crypto_tfm_ctx(req->base.tfm);
struct nx_csbcpb *csbcpb = nx_ctx->csbcpb;
unsigned int nbytes = req->cryptlen;
unsigned int authsize = crypto_aead_authsize(crypto_aead_reqtfm(req));
struct nx_ccm_priv *priv = &nx_ctx->priv.ccm;
unsigned long irq_flags;
unsigned int processed = 0, to_process;
int rc = -1;
spin_lock_irqsave(&nx_ctx->lock, irq_flags);
nbytes -= authsize;
/* copy out the auth tag to compare with later */
scatterwalk_map_and_copy(priv->oauth_tag,
req->src, nbytes + req->assoclen, authsize,
SCATTERWALK_FROM_SG);
rc = generate_pat(desc->info, req, nx_ctx, authsize, nbytes, assoclen,
csbcpb->cpb.aes_ccm.in_pat_or_b0);
if (rc)
goto out;
do {
/* to_process: the AES_BLOCK_SIZE data chunk to process in this
* update. This value is bound by sg list limits.
*/
to_process = nbytes - processed;
if ((to_process + processed) < nbytes)
NX_CPB_FDM(csbcpb) |= NX_FDM_INTERMEDIATE;
else
NX_CPB_FDM(csbcpb) &= ~NX_FDM_INTERMEDIATE;
NX_CPB_FDM(nx_ctx->csbcpb) &= ~NX_FDM_ENDE_ENCRYPT;
rc = nx_build_sg_lists(nx_ctx, desc, req->dst, req->src,
&to_process, processed + req->assoclen,
csbcpb->cpb.aes_ccm.iv_or_ctr);
if (rc)
goto out;
rc = nx_hcall_sync(nx_ctx, &nx_ctx->op,
req->base.flags & CRYPTO_TFM_REQ_MAY_SLEEP);
if (rc)
goto out;
/* for partial completion, copy following for next
* entry into loop...
*/
memcpy(desc->info, csbcpb->cpb.aes_ccm.out_ctr, AES_BLOCK_SIZE);
memcpy(csbcpb->cpb.aes_ccm.in_pat_or_b0,
csbcpb->cpb.aes_ccm.out_pat_or_mac, AES_BLOCK_SIZE);
memcpy(csbcpb->cpb.aes_ccm.in_s0,
csbcpb->cpb.aes_ccm.out_s0, AES_BLOCK_SIZE);
NX_CPB_FDM(csbcpb) |= NX_FDM_CONTINUATION;
/* update stats */
atomic_inc(&(nx_ctx->stats->aes_ops));
atomic64_add(csbcpb->csb.processed_byte_count,
&(nx_ctx->stats->aes_bytes));
processed += to_process;
} while (processed < nbytes);
rc = crypto_memneq(csbcpb->cpb.aes_ccm.out_pat_or_mac, priv->oauth_tag,
authsize) ? -EBADMSG : 0;
out:
spin_unlock_irqrestore(&nx_ctx->lock, irq_flags);
return rc;
}
static int ccm_nx_encrypt(struct aead_request *req,
struct blkcipher_desc *desc,
unsigned int assoclen)
{
struct nx_crypto_ctx *nx_ctx = crypto_tfm_ctx(req->base.tfm);
struct nx_csbcpb *csbcpb = nx_ctx->csbcpb;
unsigned int nbytes = req->cryptlen;
unsigned int authsize = crypto_aead_authsize(crypto_aead_reqtfm(req));
unsigned long irq_flags;
unsigned int processed = 0, to_process;
int rc = -1;
spin_lock_irqsave(&nx_ctx->lock, irq_flags);
rc = generate_pat(desc->info, req, nx_ctx, authsize, nbytes, assoclen,
csbcpb->cpb.aes_ccm.in_pat_or_b0);
if (rc)
goto out;
do {
/* to process: the AES_BLOCK_SIZE data chunk to process in this
* update. This value is bound by sg list limits.
*/
to_process = nbytes - processed;
if ((to_process + processed) < nbytes)
NX_CPB_FDM(csbcpb) |= NX_FDM_INTERMEDIATE;
else
NX_CPB_FDM(csbcpb) &= ~NX_FDM_INTERMEDIATE;
NX_CPB_FDM(csbcpb) |= NX_FDM_ENDE_ENCRYPT;
rc = nx_build_sg_lists(nx_ctx, desc, req->dst, req->src,
&to_process, processed + req->assoclen,
csbcpb->cpb.aes_ccm.iv_or_ctr);
if (rc)
goto out;
rc = nx_hcall_sync(nx_ctx, &nx_ctx->op,
req->base.flags & CRYPTO_TFM_REQ_MAY_SLEEP);
if (rc)
goto out;
/* for partial completion, copy following for next
* entry into loop...
*/
memcpy(desc->info, csbcpb->cpb.aes_ccm.out_ctr, AES_BLOCK_SIZE);
memcpy(csbcpb->cpb.aes_ccm.in_pat_or_b0,
csbcpb->cpb.aes_ccm.out_pat_or_mac, AES_BLOCK_SIZE);
memcpy(csbcpb->cpb.aes_ccm.in_s0,
csbcpb->cpb.aes_ccm.out_s0, AES_BLOCK_SIZE);
NX_CPB_FDM(csbcpb) |= NX_FDM_CONTINUATION;
/* update stats */
atomic_inc(&(nx_ctx->stats->aes_ops));
atomic64_add(csbcpb->csb.processed_byte_count,
&(nx_ctx->stats->aes_bytes));
processed += to_process;
} while (processed < nbytes);
/* copy out the auth tag */
scatterwalk_map_and_copy(csbcpb->cpb.aes_ccm.out_pat_or_mac,
req->dst, nbytes + req->assoclen, authsize,
SCATTERWALK_TO_SG);
out:
spin_unlock_irqrestore(&nx_ctx->lock, irq_flags);
return rc;
}
static int ccm4309_aes_nx_encrypt(struct aead_request *req)
{
struct nx_crypto_ctx *nx_ctx = crypto_tfm_ctx(req->base.tfm);
struct nx_gcm_rctx *rctx = aead_request_ctx(req);
struct blkcipher_desc desc;
u8 *iv = rctx->iv;
iv[0] = 3;
memcpy(iv + 1, nx_ctx->priv.ccm.nonce, 3);
memcpy(iv + 4, req->iv, 8);
desc.info = iv;
return ccm_nx_encrypt(req, &desc, req->assoclen - 8);
}
static int ccm_aes_nx_encrypt(struct aead_request *req)
{
struct blkcipher_desc desc;
int rc;
desc.info = req->iv;
rc = crypto_ccm_check_iv(desc.info);
if (rc)
return rc;
return ccm_nx_encrypt(req, &desc, req->assoclen);
}
static int ccm4309_aes_nx_decrypt(struct aead_request *req)
{
struct nx_crypto_ctx *nx_ctx = crypto_tfm_ctx(req->base.tfm);
struct nx_gcm_rctx *rctx = aead_request_ctx(req);
struct blkcipher_desc desc;
u8 *iv = rctx->iv;
iv[0] = 3;
memcpy(iv + 1, nx_ctx->priv.ccm.nonce, 3);
memcpy(iv + 4, req->iv, 8);
desc.info = iv;
return ccm_nx_decrypt(req, &desc, req->assoclen - 8);
}
static int ccm_aes_nx_decrypt(struct aead_request *req)
{
struct blkcipher_desc desc;
int rc;
desc.info = req->iv;
rc = crypto_ccm_check_iv(desc.info);
if (rc)
return rc;
return ccm_nx_decrypt(req, &desc, req->assoclen);
}
/* tell the block cipher walk routines that this is a stream cipher by
* setting cra_blocksize to 1. Even using blkcipher_walk_virt_block
* during encrypt/decrypt doesn't solve this problem, because it calls
* blkcipher_walk_done under the covers, which doesn't use walk->blocksize,
* but instead uses this tfm->blocksize. */
struct aead_alg nx_ccm_aes_alg = {
.base = {
.cra_name = "ccm(aes)",
.cra_driver_name = "ccm-aes-nx",
.cra_priority = 300,
.cra_flags = CRYPTO_ALG_NEED_FALLBACK,
.cra_blocksize = 1,
.cra_ctxsize = sizeof(struct nx_crypto_ctx),
.cra_module = THIS_MODULE,
},
.init = nx_crypto_ctx_aes_ccm_init,
.exit = nx_crypto_ctx_aead_exit,
.ivsize = AES_BLOCK_SIZE,
.maxauthsize = AES_BLOCK_SIZE,
.setkey = ccm_aes_nx_set_key,
.setauthsize = ccm_aes_nx_setauthsize,
.encrypt = ccm_aes_nx_encrypt,
.decrypt = ccm_aes_nx_decrypt,
};
struct aead_alg nx_ccm4309_aes_alg = {
.base = {
.cra_name = "rfc4309(ccm(aes))",
.cra_driver_name = "rfc4309-ccm-aes-nx",
.cra_priority = 300,
.cra_flags = CRYPTO_ALG_NEED_FALLBACK,
.cra_blocksize = 1,
.cra_ctxsize = sizeof(struct nx_crypto_ctx),
.cra_module = THIS_MODULE,
},
.init = nx_crypto_ctx_aes_ccm_init,
.exit = nx_crypto_ctx_aead_exit,
.ivsize = 8,
.maxauthsize = AES_BLOCK_SIZE,
.setkey = ccm4309_aes_nx_set_key,
.setauthsize = ccm4309_aes_nx_setauthsize,
.encrypt = ccm4309_aes_nx_encrypt,
.decrypt = ccm4309_aes_nx_decrypt,
};