From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752696AbeAVJQO (ORCPT ); Mon, 22 Jan 2018 04:16:14 -0500 Received: from mail-pf0-f196.google.com ([209.85.192.196]:43351 "EHLO mail-pf0-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751351AbeAVJQJ (ORCPT ); Mon, 22 Jan 2018 04:16:09 -0500 X-Google-Smtp-Source: AH8x224MOwBWZDFWGzHcgpl9PLHt/6JLX1jg69AVcGY9dSN2oTsb+FkAcCPkrglA0RZ9gPhdIQi6hl3iTO0503U6M2Y= MIME-Version: 1.0 In-Reply-To: <1516380970.3772.112.camel@linux.vnet.ibm.com> References: <20180116151000.443-1-alban@kinvolk.io> <1516310702.3772.11.camel@linux.vnet.ibm.com> <1516380970.3772.112.camel@linux.vnet.ibm.com> From: Alban Crequy Date: Mon, 22 Jan 2018 10:16:07 +0100 Message-ID: Subject: Re: [RFC PATCH v2] ima,fuse: introduce new fs flag FS_NO_IMA_CACHE To: Mimi Zohar Cc: Alban Crequy , =?UTF-8?Q?Iago_L=C3=B3pez_Galeiras?= , Dongsu Park , LKML , linux-integrity@vger.kernel.org, linux-security-module@vger.kernel.org, linux-fsdevel@vger.kernel.org, Miklos Szeredi , Alexander Viro , Dmitry Kasatkin , James Morris , "Serge E. Hallyn" , Seth Forshee , Christoph Hellwig Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jan 19, 2018 at 5:56 PM, Mimi Zohar wrote: > On Fri, 2018-01-19 at 11:35 +0100, Alban Crequy wrote: >> On Thu, Jan 18, 2018 at 10:25 PM, Mimi Zohar wrote: >> > On Tue, 2018-01-16 at 16:10 +0100, Alban Crequy wrote: >> >> From: Alban Crequy >> >> >> >> This patch forces files to be re-measured, re-appraised and re-audited >> >> on file systems with the feature flag FS_NO_IMA_CACHE. In that way, >> >> cached integrity results won't be used. >> >> >> >> For now, this patch adds the new flag only FUSE filesystems. This is >> >> needed because the userspace FUSE process can change the underlying >> >> files at any time. >> > >> > Thanks, it's working nicely. >> > >> > >> >> diff --git a/include/linux/fs.h b/include/linux/fs.h >> >> index 511fbaabf624..2bd7e73ebc2a 100644 >> >> --- a/include/linux/fs.h >> >> +++ b/include/linux/fs.h >> >> @@ -2075,6 +2075,7 @@ struct file_system_type { >> >> #define FS_BINARY_MOUNTDATA 2 >> >> #define FS_HAS_SUBTYPE 4 >> >> #define FS_USERNS_MOUNT 8 /* Can be mounted by userns root */ >> >> +#define FS_NO_IMA_CACHE 16 /* Force IMA to re-measure, re-appraise, re-audit files */ >> >> #define FS_RENAME_DOES_D_MOVE 32768 /* FS will handle d_move() during rename() internally. */ >> >> struct dentry *(*mount) (struct file_system_type *, int, >> >> const char *, void *); >> >> >> > >> > Since IMA is going to need another flag, we probably should have a >> > consistent prefix (eg. "FS_IMA"). Maybe rename this flag to >> > FS_IMA_NO_CACHE. >> >> Ok, I can rename it. >> >> Is there a discussion about the other IMA flag? > > There's not a single thread that I can point to, but more of an on > going discussion as to what it means for a filesystem to support IMA > and how that decision is made. > > - Initial measuring, verifying, auditing files > - Safely detecting when a file changes > - Not applicable/supported > > With Sascha Hauer's patch "ima: Use i_version only when filesystem > supports it" and this patch, the second issue is addressed, but will > cause files to be re-validated, perhaps unnecessarily, impacting > performance. > > Some filesystems should not be evaluated, such as pseudo filesystems > (eg. cgroups, sysfs, devpts, pstorefs, efivarfs, debugfs, selinux, > smack). Instead of defining a flag indicating whether or not IMA is > applicable/supported, we should define a new flag, indicating whether > it is a pseudo filesystem. This would eliminate a large portion of at > least the builtin IMA policy rules. Thanks for the explanation. If that other flag is about whether it is a pseudo filesystem, it might not have "IMA" in the name though. >> > I'm also wondering if this change should be >> > separated from the IMA change. >> >> Do you mean one patch for adding the flag and the IMA change and >> another patch for using the flag in FUSE? > > The flag and FUSE usage of the flag, separately from IMA. Ok, I will send a v3 with the 2 changes. Alban From mboxrd@z Thu Jan 1 00:00:00 1970 From: alban@kinvolk.io (Alban Crequy) Date: Mon, 22 Jan 2018 10:16:07 +0100 Subject: [RFC PATCH v2] ima,fuse: introduce new fs flag FS_NO_IMA_CACHE In-Reply-To: <1516380970.3772.112.camel@linux.vnet.ibm.com> References: <20180116151000.443-1-alban@kinvolk.io> <1516310702.3772.11.camel@linux.vnet.ibm.com> <1516380970.3772.112.camel@linux.vnet.ibm.com> Message-ID: To: linux-security-module@vger.kernel.org List-Id: linux-security-module.vger.kernel.org On Fri, Jan 19, 2018 at 5:56 PM, Mimi Zohar wrote: > On Fri, 2018-01-19 at 11:35 +0100, Alban Crequy wrote: >> On Thu, Jan 18, 2018 at 10:25 PM, Mimi Zohar wrote: >> > On Tue, 2018-01-16 at 16:10 +0100, Alban Crequy wrote: >> >> From: Alban Crequy >> >> >> >> This patch forces files to be re-measured, re-appraised and re-audited >> >> on file systems with the feature flag FS_NO_IMA_CACHE. In that way, >> >> cached integrity results won't be used. >> >> >> >> For now, this patch adds the new flag only FUSE filesystems. This is >> >> needed because the userspace FUSE process can change the underlying >> >> files at any time. >> > >> > Thanks, it's working nicely. >> > >> > >> >> diff --git a/include/linux/fs.h b/include/linux/fs.h >> >> index 511fbaabf624..2bd7e73ebc2a 100644 >> >> --- a/include/linux/fs.h >> >> +++ b/include/linux/fs.h >> >> @@ -2075,6 +2075,7 @@ struct file_system_type { >> >> #define FS_BINARY_MOUNTDATA 2 >> >> #define FS_HAS_SUBTYPE 4 >> >> #define FS_USERNS_MOUNT 8 /* Can be mounted by userns root */ >> >> +#define FS_NO_IMA_CACHE 16 /* Force IMA to re-measure, re-appraise, re-audit files */ >> >> #define FS_RENAME_DOES_D_MOVE 32768 /* FS will handle d_move() during rename() internally. */ >> >> struct dentry *(*mount) (struct file_system_type *, int, >> >> const char *, void *); >> >> >> > >> > Since IMA is going to need another flag, we probably should have a >> > consistent prefix (eg. "FS_IMA"). Maybe rename this flag to >> > FS_IMA_NO_CACHE. >> >> Ok, I can rename it. >> >> Is there a discussion about the other IMA flag? > > There's not a single thread that I can point to, but more of an on > going discussion as to what it means for a filesystem to support IMA > and how that decision is made. > > - Initial measuring, verifying, auditing files > - Safely detecting when a file changes > - Not applicable/supported > > With Sascha Hauer's patch "ima: Use i_version only when filesystem > supports it" and this patch, the second issue is addressed, but will > cause files to be re-validated, perhaps unnecessarily, impacting > performance. > > Some filesystems should not be evaluated, such as pseudo filesystems > (eg. cgroups, sysfs, devpts, pstorefs, efivarfs, debugfs, selinux, > smack). Instead of defining a flag indicating whether or not IMA is > applicable/supported, we should define a new flag, indicating whether > it is a pseudo filesystem. This would eliminate a large portion of at > least the builtin IMA policy rules. Thanks for the explanation. If that other flag is about whether it is a pseudo filesystem, it might not have "IMA" in the name though. >> > I'm also wondering if this change should be >> > separated from the IMA change. >> >> Do you mean one patch for adding the flag and the IMA change and >> another patch for using the flag in FUSE? > > The flag and FUSE usage of the flag, separately from IMA. Ok, I will send a v3 with the 2 changes. Alban -- To unsubscribe from this list: send the line "unsubscribe linux-security-module" in the body of a message to majordomo at vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html