From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:58504 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1753227AbdI1Odp (ORCPT ); Thu, 28 Sep 2017 10:33:45 -0400 Received: from pps.filterd (m0098416.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.21/8.16.0.21) with SMTP id v8SEXWcs073824 for ; Thu, 28 Sep 2017 10:33:44 -0400 Received: from e23smtp01.au.ibm.com (e23smtp01.au.ibm.com [202.81.31.143]) by mx0b-001b2d01.pphosted.com with ESMTP id 2d8yxs40tr-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Thu, 28 Sep 2017 10:33:43 -0400 Received: from localhost by e23smtp01.au.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Fri, 29 Sep 2017 00:33:31 +1000 Subject: Re: [RFC PATCH 1/3] fs: define new read_iter rwf flag From: Mimi Zohar To: Matthew Wilcox Cc: linux-security-module@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-integrity@vger.kernel.org, Christoph Hellwig , Linus Torvalds , Linux Kernel Mailing List , Jan Kara , "Theodore Ts'o" Date: Thu, 28 Sep 2017 10:33:23 -0400 In-Reply-To: <20170928135416.GA30859@bombadil.infradead.org> References: <1506602373-4799-1-git-send-email-zohar@linux.vnet.ibm.com> <1506602373-4799-2-git-send-email-zohar@linux.vnet.ibm.com> <20170928135416.GA30859@bombadil.infradead.org> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Message-Id: <1506609203.5022.1.camel@linux.vnet.ibm.com> Sender: linux-integrity-owner@vger.kernel.org List-ID: On Thu, 2017-09-28 at 06:54 -0700, Matthew Wilcox wrote: > On Thu, Sep 28, 2017 at 08:39:31AM -0400, Mimi Zohar wrote: > > Writing extended attributes requires exclusively taking the i_rwsem > > lock. To synchronize the file hash calculation and writing the file > > hash as security.ima xattr, IMA-appraisal takes the i_rwsem lock > > exclusively before calculating the file hash. (Once the file hash > > is calculated, the result is cached. Taking the lock exclusively > > prevents calculating the file hash multiple times.) > > > > Some filesystems have recently replaced their filesystem dependent > > lock with the global i_rwsem to read a file. As a result, when IMA > > attempts to calculate the file hash, reading the file attempts to > > take the i_rwsem again. > > > > To resolve this problem, this patch defines a new read_iter flag > > named "rwf" to indicate that the i_rwsem has already been taken > > exclusively. Subsequent patches will set or test the "rwf" flag. > > I don't like adding a bool parameter everywhere. Me either! > Why not add a flag > to the kiocb ki_flags? > > #define IOCB_RWSEM_HELD (1 << 8) Thank you for the suggestion. > -- > To unsubscribe from this list: send the line "unsubscribe linux-security-module" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html >