From patchwork Tue Apr 28 07:30:10 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Roberto Sassu X-Patchwork-Id: 11513967 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 9B9301392 for ; Tue, 28 Apr 2020 07:32:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 82600206B9 for ; Tue, 28 Apr 2020 07:32:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726279AbgD1Hco (ORCPT ); Tue, 28 Apr 2020 03:32:44 -0400 Received: from lhrrgout.huawei.com ([185.176.76.210]:2117 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726274AbgD1Hcn (ORCPT ); Tue, 28 Apr 2020 03:32:43 -0400 Received: from lhreml743-chm.china.huawei.com (unknown [172.18.7.106]) by Forcepoint Email with ESMTP id BA2CFD6E8C5E08530288; Tue, 28 Apr 2020 08:32:41 +0100 (IST) Received: from fraeml714-chm.china.huawei.com (10.206.15.33) by lhreml743-chm.china.huawei.com (10.201.108.193) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.1913.5; Tue, 28 Apr 2020 08:32:41 +0100 Received: from roberto-HP-EliteDesk-800-G2-DM-65W.huawei.com (10.204.65.160) by fraeml714-chm.china.huawei.com (10.206.15.33) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.1913.5; Tue, 28 Apr 2020 09:32:40 +0200 From: Roberto Sassu To: , , CC: , , , , , , Roberto Sassu Subject: [RESEND][PATCH v2 3/6] ima: Fix ima digest hash table key calculation Date: Tue, 28 Apr 2020 09:30:10 +0200 Message-ID: <20200428073010.25631-1-roberto.sassu@huawei.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20200427102900.18887-3-roberto.sassu@huawei.com> References: <20200427102900.18887-3-roberto.sassu@huawei.com> MIME-Version: 1.0 X-Originating-IP: [10.204.65.160] X-ClientProxiedBy: lhreml736-chm.china.huawei.com (10.201.108.87) To fraeml714-chm.china.huawei.com (10.206.15.33) X-CFilter-Loop: Reflected Sender: linux-integrity-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-integrity@vger.kernel.org From: Krzysztof Struczynski Function hash_long() accepts unsigned long, while currently only one byte is passed from ima_hash_key(), which calculates a key for ima_htable. Given that hashing the digest does not give clear benefits compared to using the digest itself, remove hash_long() and return the modulus calculated on the first two bytes of the digest with the number of slots. Also reduce the depth of the hash table by doubling the number of slots. Changelog v2: directly access the first two bytes of the digest to avoid memory access issues on big endian systems (suggested by David Laight) Cc: stable@vger.kernel.org Fixes: 3323eec921ef ("integrity: IMA as an integrity service provider") Co-developed-by: Roberto Sassu Signed-off-by: Roberto Sassu Signed-off-by: Krzysztof Struczynski Acked-by: David.Laight@aculab.com --- security/integrity/ima/ima.h | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h index 467dfdbea25c..02796473238b 100644 --- a/security/integrity/ima/ima.h +++ b/security/integrity/ima/ima.h @@ -36,7 +36,7 @@ enum tpm_pcrs { TPM_PCR0 = 0, TPM_PCR8 = 8 }; #define IMA_DIGEST_SIZE SHA1_DIGEST_SIZE #define IMA_EVENT_NAME_LEN_MAX 255 -#define IMA_HASH_BITS 9 +#define IMA_HASH_BITS 10 #define IMA_MEASURE_HTABLE_SIZE (1 << IMA_HASH_BITS) #define IMA_TEMPLATE_FIELD_ID_MAX_LEN 16 @@ -179,9 +179,10 @@ struct ima_h_table { }; extern struct ima_h_table ima_htable; -static inline unsigned long ima_hash_key(u8 *digest) +static inline unsigned int ima_hash_key(u8 *digest) { - return hash_long(*digest, IMA_HASH_BITS); + /* there is no point in taking a hash of part of a digest */ + return (digest[0] | digest[1] << 8) % IMA_MEASURE_HTABLE_SIZE; } #define __ima_hooks(hook) \