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![Kees Cook](/assets/img/avatar_default.png)
In the quest to remove all stack VLA usage from the kernel[1], this replaces struct crypto_skcipher and SKCIPHER_REQUEST_ON_STACK() usage with struct crypto_sync_skcipher and SYNC_SKCIPHER_REQUEST_ON_STACK(), which uses a fixed stack size. [1] https://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qPXydAacU1RqZWA@mail.gmail.com Cc: "Leonidas S. Barbosa" <leosilva@linux.vnet.ibm.com> Cc: Paulo Flabiano Smorigo <pfsmorigo@linux.vnet.ibm.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: linuxppc-dev@lists.ozlabs.org Signed-off-by: Kees Cook <keescook@chromium.org> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
190 lines
5.2 KiB
C
190 lines
5.2 KiB
C
/**
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* AES XTS routines supporting VMX In-core instructions on Power 8
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*
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* Copyright (C) 2015 International Business Machines Inc.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundations; version 2 only.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY of FITNESS FOR A PARTICUPAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*
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* Author: Leonidas S. Barbosa <leosilva@linux.vnet.ibm.com>
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*/
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#include <linux/types.h>
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#include <linux/err.h>
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#include <linux/crypto.h>
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#include <linux/delay.h>
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#include <linux/hardirq.h>
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#include <asm/switch_to.h>
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#include <crypto/aes.h>
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#include <crypto/scatterwalk.h>
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#include <crypto/xts.h>
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#include <crypto/skcipher.h>
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#include "aesp8-ppc.h"
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struct p8_aes_xts_ctx {
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struct crypto_sync_skcipher *fallback;
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struct aes_key enc_key;
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struct aes_key dec_key;
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struct aes_key tweak_key;
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};
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static int p8_aes_xts_init(struct crypto_tfm *tfm)
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{
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const char *alg = crypto_tfm_alg_name(tfm);
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struct crypto_sync_skcipher *fallback;
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struct p8_aes_xts_ctx *ctx = crypto_tfm_ctx(tfm);
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fallback = crypto_alloc_sync_skcipher(alg, 0,
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CRYPTO_ALG_NEED_FALLBACK);
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if (IS_ERR(fallback)) {
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printk(KERN_ERR
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"Failed to allocate transformation for '%s': %ld\n",
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alg, PTR_ERR(fallback));
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return PTR_ERR(fallback);
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}
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crypto_sync_skcipher_set_flags(
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fallback,
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crypto_skcipher_get_flags((struct crypto_skcipher *)tfm));
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ctx->fallback = fallback;
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return 0;
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}
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static void p8_aes_xts_exit(struct crypto_tfm *tfm)
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{
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struct p8_aes_xts_ctx *ctx = crypto_tfm_ctx(tfm);
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if (ctx->fallback) {
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crypto_free_sync_skcipher(ctx->fallback);
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ctx->fallback = NULL;
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}
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}
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static int p8_aes_xts_setkey(struct crypto_tfm *tfm, const u8 *key,
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unsigned int keylen)
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{
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int ret;
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struct p8_aes_xts_ctx *ctx = crypto_tfm_ctx(tfm);
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ret = xts_check_key(tfm, key, keylen);
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if (ret)
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return ret;
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preempt_disable();
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pagefault_disable();
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enable_kernel_vsx();
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ret = aes_p8_set_encrypt_key(key + keylen/2, (keylen/2) * 8, &ctx->tweak_key);
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ret += aes_p8_set_encrypt_key(key, (keylen/2) * 8, &ctx->enc_key);
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ret += aes_p8_set_decrypt_key(key, (keylen/2) * 8, &ctx->dec_key);
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disable_kernel_vsx();
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pagefault_enable();
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preempt_enable();
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ret += crypto_sync_skcipher_setkey(ctx->fallback, key, keylen);
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return ret;
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}
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static int p8_aes_xts_crypt(struct blkcipher_desc *desc,
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struct scatterlist *dst,
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struct scatterlist *src,
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unsigned int nbytes, int enc)
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{
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int ret;
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u8 tweak[AES_BLOCK_SIZE];
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u8 *iv;
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struct blkcipher_walk walk;
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struct p8_aes_xts_ctx *ctx =
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crypto_tfm_ctx(crypto_blkcipher_tfm(desc->tfm));
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if (in_interrupt()) {
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SYNC_SKCIPHER_REQUEST_ON_STACK(req, ctx->fallback);
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skcipher_request_set_sync_tfm(req, ctx->fallback);
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skcipher_request_set_callback(req, desc->flags, NULL, NULL);
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skcipher_request_set_crypt(req, src, dst, nbytes, desc->info);
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ret = enc? crypto_skcipher_encrypt(req) : crypto_skcipher_decrypt(req);
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skcipher_request_zero(req);
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} else {
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blkcipher_walk_init(&walk, dst, src, nbytes);
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ret = blkcipher_walk_virt(desc, &walk);
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preempt_disable();
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pagefault_disable();
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enable_kernel_vsx();
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iv = walk.iv;
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memset(tweak, 0, AES_BLOCK_SIZE);
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aes_p8_encrypt(iv, tweak, &ctx->tweak_key);
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disable_kernel_vsx();
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pagefault_enable();
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preempt_enable();
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while ((nbytes = walk.nbytes)) {
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preempt_disable();
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pagefault_disable();
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enable_kernel_vsx();
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if (enc)
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aes_p8_xts_encrypt(walk.src.virt.addr, walk.dst.virt.addr,
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nbytes & AES_BLOCK_MASK, &ctx->enc_key, NULL, tweak);
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else
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aes_p8_xts_decrypt(walk.src.virt.addr, walk.dst.virt.addr,
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nbytes & AES_BLOCK_MASK, &ctx->dec_key, NULL, tweak);
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disable_kernel_vsx();
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pagefault_enable();
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preempt_enable();
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nbytes &= AES_BLOCK_SIZE - 1;
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ret = blkcipher_walk_done(desc, &walk, nbytes);
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}
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}
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return ret;
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}
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static int p8_aes_xts_encrypt(struct blkcipher_desc *desc,
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struct scatterlist *dst,
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struct scatterlist *src, unsigned int nbytes)
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{
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return p8_aes_xts_crypt(desc, dst, src, nbytes, 1);
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}
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static int p8_aes_xts_decrypt(struct blkcipher_desc *desc,
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struct scatterlist *dst,
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struct scatterlist *src, unsigned int nbytes)
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{
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return p8_aes_xts_crypt(desc, dst, src, nbytes, 0);
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}
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struct crypto_alg p8_aes_xts_alg = {
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.cra_name = "xts(aes)",
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.cra_driver_name = "p8_aes_xts",
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.cra_module = THIS_MODULE,
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.cra_priority = 2000,
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.cra_type = &crypto_blkcipher_type,
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.cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER | CRYPTO_ALG_NEED_FALLBACK,
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.cra_alignmask = 0,
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.cra_blocksize = AES_BLOCK_SIZE,
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.cra_ctxsize = sizeof(struct p8_aes_xts_ctx),
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.cra_init = p8_aes_xts_init,
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.cra_exit = p8_aes_xts_exit,
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.cra_blkcipher = {
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.ivsize = AES_BLOCK_SIZE,
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.min_keysize = 2 * AES_MIN_KEY_SIZE,
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.max_keysize = 2 * AES_MAX_KEY_SIZE,
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.setkey = p8_aes_xts_setkey,
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.encrypt = p8_aes_xts_encrypt,
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.decrypt = p8_aes_xts_decrypt,
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}
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};
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