From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Biggers Subject: [PATCH v2 08/12] fs-verity: add CRC-32C support Date: Thu, 1 Nov 2018 15:52:26 -0700 Message-ID: <20181101225230.88058-9-ebiggers@kernel.org> References: <20181101225230.88058-1-ebiggers@kernel.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from [172.30.20.202] (helo=mx.sourceforge.net) by sfs-ml-2.v29.lw.sourceforge.com with esmtps (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.90_1) (envelope-from ) id 1gILrF-0007QC-6r for linux-f2fs-devel@lists.sourceforge.net; Thu, 01 Nov 2018 22:54:33 +0000 Received: from mail.kernel.org ([198.145.29.99]) by sfi-mx-3.v28.lw.sourceforge.com with esmtps (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.90_1) id 1gILrD-00H2gU-UV for linux-f2fs-devel@lists.sourceforge.net; Thu, 01 Nov 2018 22:54:33 +0000 In-Reply-To: <20181101225230.88058-1-ebiggers@kernel.org> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: linux-f2fs-devel-bounces@lists.sourceforge.net To: linux-fscrypt@vger.kernel.org Cc: "Theodore Y . Ts'o" , linux-kernel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, linux-fsdevel@vger.kernel.org, Jaegeuk Kim , linux-integrity@vger.kernel.org, linux-ext4@vger.kernel.org, Victor Hsieh From: Eric Biggers Add CRC-32C support to fs-verity, to provide a faster alternative to SHA-256 for users who want integrity-only (not authenticity), i.e. who want to detect only accidental corruption, not malicious changes. CRC-32C is chosen over CRC-32 because the CRC-32C polynomial is believed to provide slightly better error-detection properties; and CRC-32C is just as fast (or can be just as fast) as CRC-32, or even faster e.g. on some x86 processors that have a CRC-32C instruction but not CRC-32. We use "crc32c" from the crypto API, so the polynomial convention is bitwise little-endian, the digest is bytewise little-endian, and the CRC bits are inverted at the beginning and end (which is desirable). Signed-off-by: Eric Biggers --- fs/verity/hash_algs.c | 4 ++++ include/uapi/linux/fsverity.h | 1 + 2 files changed, 5 insertions(+) diff --git a/fs/verity/hash_algs.c b/fs/verity/hash_algs.c index 3174a0c08785d..109afeec60fc9 100644 --- a/fs/verity/hash_algs.c +++ b/fs/verity/hash_algs.c @@ -23,6 +23,10 @@ struct fsverity_hash_alg fsverity_hash_algs[] = { .digest_size = 64, .cryptographic = true, }, + [FS_VERITY_ALG_CRC32C] = { + .name = "crc32c", + .digest_size = 4, + }, }; /* diff --git a/include/uapi/linux/fsverity.h b/include/uapi/linux/fsverity.h index 67ed830ae2ece..a96bbf87077de 100644 --- a/include/uapi/linux/fsverity.h +++ b/include/uapi/linux/fsverity.h @@ -29,6 +29,7 @@ struct fsverity_digest { /* Supported hash algorithms */ #define FS_VERITY_ALG_SHA256 1 #define FS_VERITY_ALG_SHA512 2 +#define FS_VERITY_ALG_CRC32C 3 /* for integrity only */ /* Metadata stored near the end of verity files, after the Merkle tree */ /* This structure is 64 bytes long */ -- 2.19.1.568.g152ad8e336-goog