From: Harald Freudenberger Subject: [PATCH] crypto: s390 - fix concurrency issue in aes-ctr mode Date: Thu, 16 Jan 2014 16:01:11 +0100 Message-ID: <1389884471-24964-1-git-send-email-freude@linux.vnet.ibm.com> Cc: linux-crypto@vger.kernel.org, Martin Schwidefsky , Ingo Tuchscherer , Gerald Schaefer , Harald Freudenberger , Harald Freudenberger To: Herbert Xu Return-path: Received: from e06smtp12.uk.ibm.com ([195.75.94.108]:38698 "EHLO e06smtp12.uk.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751271AbaAPPBa (ORCPT ); Thu, 16 Jan 2014 10:01:30 -0500 Received: from /spool/local by e06smtp12.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Thu, 16 Jan 2014 15:01:28 -0000 Received: from b06cxnps4074.portsmouth.uk.ibm.com (d06relay11.portsmouth.uk.ibm.com [9.149.109.196]) by d06dlp02.portsmouth.uk.ibm.com (Postfix) with ESMTP id 3C267219005E for ; Thu, 16 Jan 2014 15:01:25 +0000 (GMT) Received: from d06av06.portsmouth.uk.ibm.com (d06av06.portsmouth.uk.ibm.com [9.149.37.217]) by b06cxnps4074.portsmouth.uk.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id s0GF1Ekm65798206 for ; Thu, 16 Jan 2014 15:01:14 GMT Received: from d06av06.portsmouth.uk.ibm.com (localhost [127.0.0.1]) by d06av06.portsmouth.uk.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id s0GF1PLc015045 for ; Thu, 16 Jan 2014 08:01:26 -0700 Sender: linux-crypto-owner@vger.kernel.org List-ID: The aes-ctr mode uses one preallocated page without any concurrency protection. When multiple threads run aes-ctr encryption or decryption this can lead to data corruption. The patch introduces locking for the page and a fallback solution with slower en/decryption performance in concurrency situations. Signed-off-by: Harald Freudenberger --- arch/s390/crypto/aes_s390.c | 65 ++++++++++++++++++++++++++++++------------- 1 file changed, 46 insertions(+), 19 deletions(-) diff --git a/arch/s390/crypto/aes_s390.c b/arch/s390/crypto/aes_s390.c index b3feabd..cf3c008 100644 --- a/arch/s390/crypto/aes_s390.c +++ b/arch/s390/crypto/aes_s390.c @@ -25,6 +25,7 @@ #include #include #include +#include #include "crypt_s390.h" #define AES_KEYLEN_128 1 @@ -32,6 +33,7 @@ #define AES_KEYLEN_256 4 static u8 *ctrblk; +static DEFINE_SPINLOCK(ctrblk_lock); static char keylen_flag; struct s390_aes_ctx { @@ -758,43 +760,67 @@ static int ctr_aes_set_key(struct crypto_tfm *tfm, const u8 *in_key, return aes_set_key(tfm, in_key, key_len); } +static unsigned int __ctrblk_init(u8 *ctrptr, unsigned int nbytes) +{ + unsigned int i, n; + + /* only use complete blocks, max. PAGE_SIZE */ + n = (nbytes > PAGE_SIZE) ? PAGE_SIZE : nbytes & ~(AES_BLOCK_SIZE - 1); + for (i = AES_BLOCK_SIZE; i < n; i += AES_BLOCK_SIZE) { + memcpy(ctrptr + i, ctrptr + i - AES_BLOCK_SIZE, + AES_BLOCK_SIZE); + crypto_inc(ctrptr + i, AES_BLOCK_SIZE); + } + return n; +} + static int ctr_aes_crypt(struct blkcipher_desc *desc, long func, struct s390_aes_ctx *sctx, struct blkcipher_walk *walk) { int ret = blkcipher_walk_virt_block(desc, walk, AES_BLOCK_SIZE); - unsigned int i, n, nbytes; - u8 buf[AES_BLOCK_SIZE]; - u8 *out, *in; + unsigned int n, nbytes; + u8 buf[AES_BLOCK_SIZE], ctrbuf[AES_BLOCK_SIZE]; + u8 *out, *in, *ctrptr = ctrbuf; if (!walk->nbytes) return ret; - memcpy(ctrblk, walk->iv, AES_BLOCK_SIZE); + if (spin_trylock(&ctrblk_lock)) + ctrptr = ctrblk; + + memcpy(ctrptr, walk->iv, AES_BLOCK_SIZE); while ((nbytes = walk->nbytes) >= AES_BLOCK_SIZE) { out = walk->dst.virt.addr; in = walk->src.virt.addr; while (nbytes >= AES_BLOCK_SIZE) { - /* only use complete blocks, max. PAGE_SIZE */ - n = (nbytes > PAGE_SIZE) ? PAGE_SIZE : - nbytes & ~(AES_BLOCK_SIZE - 1); - for (i = AES_BLOCK_SIZE; i < n; i += AES_BLOCK_SIZE) { - memcpy(ctrblk + i, ctrblk + i - AES_BLOCK_SIZE, - AES_BLOCK_SIZE); - crypto_inc(ctrblk + i, AES_BLOCK_SIZE); - } - ret = crypt_s390_kmctr(func, sctx->key, out, in, n, ctrblk); - if (ret < 0 || ret != n) + if (ctrptr == ctrblk) + n = __ctrblk_init(ctrptr, nbytes); + else + n = AES_BLOCK_SIZE; + ret = crypt_s390_kmctr(func, sctx->key, out, in, + n, ctrptr); + if (ret < 0 || ret != n) { + if (ctrptr == ctrblk) + spin_unlock(&ctrblk_lock); return -EIO; + } if (n > AES_BLOCK_SIZE) - memcpy(ctrblk, ctrblk + n - AES_BLOCK_SIZE, + memcpy(ctrptr, ctrptr + n - AES_BLOCK_SIZE, AES_BLOCK_SIZE); - crypto_inc(ctrblk, AES_BLOCK_SIZE); + crypto_inc(ctrptr, AES_BLOCK_SIZE); out += n; in += n; nbytes -= n; } ret = blkcipher_walk_done(desc, walk, nbytes); } + if (ctrptr == ctrblk) { + if (nbytes) + memcpy(ctrbuf, ctrptr, AES_BLOCK_SIZE); + else + memcpy(walk->iv, ctrptr, AES_BLOCK_SIZE); + spin_unlock(&ctrblk_lock); + } /* * final block may be < AES_BLOCK_SIZE, copy only nbytes */ @@ -802,14 +828,15 @@ static int ctr_aes_crypt(struct blkcipher_desc *desc, long func, out = walk->dst.virt.addr; in = walk->src.virt.addr; ret = crypt_s390_kmctr(func, sctx->key, buf, in, - AES_BLOCK_SIZE, ctrblk); + AES_BLOCK_SIZE, ctrbuf); if (ret < 0 || ret != AES_BLOCK_SIZE) return -EIO; memcpy(out, buf, nbytes); - crypto_inc(ctrblk, AES_BLOCK_SIZE); + crypto_inc(ctrbuf, AES_BLOCK_SIZE); ret = blkcipher_walk_done(desc, walk, 0); + memcpy(walk->iv, ctrbuf, AES_BLOCK_SIZE); } - memcpy(walk->iv, ctrblk, AES_BLOCK_SIZE); + return ret; } -- 1.7.9.5