linux-kernel - Re: [PATCH 1/2] audit: add support for the openat2 syscall

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Date:   Thu, 18 Mar 2021 08:03:04 -0400
From:   Richard Guy Briggs <rgb@...hat.com>
To:     Christian Brauner <christian.brauner@...ntu.com>
Cc:     Linux-Audit Mailing List <linux-audit@...hat.com>,
        LKML <linux-kernel@...r.kernel.org>,
        Paul Moore <paul@...l-moore.com>,
        Eric Paris <eparis@...isplace.org>,
        Steve Grubb <sgrubb@...hat.com>, x86@...nel.org,
        Alexander Viro <viro@...iv.linux.org.uk>,
        Eric Paris <eparis@...hat.com>, linux-alpha@...r.kernel.org,
        linux-ia64@...r.kernel.org, linux-parisc@...r.kernel.org,
        linuxppc-dev@...ts.ozlabs.org, linux-s390@...r.kernel.org,
        sparclinux@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        Aleksa Sarai <cyphar@...har.com>
Subject: Re: [PATCH 1/2] audit: add support for the openat2 syscall

On 2021-03-18 11:52, Christian Brauner wrote:
> On Thu, Mar 18, 2021 at 11:48:45AM +0100, Christian Brauner wrote:
> > On Wed, Mar 17, 2021 at 09:47:17PM -0400, Richard Guy Briggs wrote:
> > > The openat2(2) syscall was added in kernel v5.6 with commit fddb5d430ad9
> > > ("open: introduce openat2(2) syscall")
> > > Add the openat2(2) syscall to the audit syscall classifier.
> > > See the github issue
> > > https://github.com/linux-audit/audit-kernel/issues/67
> > > Signed-off-by: Richard Guy Briggs <rgb@...hat.com>

...

> And one more comment, why return a hard-coded integer from all of these
> architectures instead of introducing an enum in a central place with
> proper names idk:

Oh, believe me, I tried hard to do that because I really don't like
hard-coded magic values, but for expediency I continued the same
approach until I could sort out the header file mess.  There was an
extra preparatory patch (attached) in this patchset with a different
audit syscall perms patch (also attached).  By including "#include
<linux/audit.h>" in each of the compat source files there were warnings
of redefinitions of every __NR_* syscall number.  The easiest way to get
rid of it would have been to pull the new AUDITSC_* definitions into a
new <linux/auditsc.h> file and include that from <linux/audit.h> and
each of the arch/*/*/*audit.c (and lib/*audit.c) files.

> enum audit_match_perm_t {
> 	.
> 	.
> 	.
> 	AUDIT_MATCH_PERM_EXECVE = 5,
> 	AUDIT_MATCH_PERM_OPENAT2 = 6,
> 	.
> 	.
> 	.
> }
> 
> Then you can drop these hard-coded comments too and it's way less
> brittle overall.

Totally agree.

> Christian

- RGB

--
Richard Guy Briggs <rgb@...hat.com>
Sr. S/W Engineer, Kernel Security, Base Operating Systems
Remote, Ottawa, Red Hat Canada
IRC: rgb, SunRaycer
Voice: +1.647.777.2635, Internal: (81) 32635

View attachment "0001-audit-replace-magic-audit-syscall-class-numbers-with.patch" of type "text/plain" (12191 bytes)

View attachment "0002-audit-add-support-for-the-openat2-syscall.patch" of type "text/plain" (8020 bytes)