From: Richard Guy Briggs <rgb@redhat.com>
To: Paul Moore <paul@paul-moore.com>
Cc: Jeff Mahoney <jeffm@suse.com>,
Linux-Audit Mailing List <linux-audit@redhat.com>,
LKML <linux-kernel@vger.kernel.org>,
linux-fsdevel@vger.kernel.org, Eric Paris <eparis@parisplace.org>,
Steve Grubb <sgrubb@redhat.com>,
Alexander Viro <viro@zeniv.linux.org.uk>,
Eric Paris <eparis@redhat.com>, Tony Jones <tonyj@suse.de>
Subject: Re: [PATCH v4 2/3] audit: add support for the openat2 syscall
Date: Wed, 9 Feb 2022 17:13:52 -0500 [thread overview]
Message-ID: <20220209221352.GG1708086@madcap2.tricolour.ca> (raw)
In-Reply-To: <CAHC9VhRCBMtWWscTFWe4W_F_KNdfLys7e5Ged+N_xddD2tkuRQ@mail.gmail.com>
On 2022-02-09 16:18, Paul Moore wrote:
> On Wed, Feb 9, 2022 at 10:57 AM Paul Moore <paul@paul-moore.com> wrote:
> > On Tue, Feb 8, 2022 at 10:44 PM Jeff Mahoney <jeffm@suse.com> wrote:
> > >
> > > Hi Richard -
> > >
> > > On 5/19/21 16:00, 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.
> > > >
> > > > Link: https://github.com/linux-audit/audit-kernel/issues/67
> > > > Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
> > > > Link: https://lore.kernel.org/r/f5f1a4d8699613f8c02ce762807228c841c2e26f.1621363275.git.rgb@redhat.com
> > > > ---
> > >
> > > [...]
> > >
> > > > diff --git a/kernel/auditsc.c b/kernel/auditsc.c
> > > > index d775ea16505b..3f59ab209dfd 100644
> > > > --- a/kernel/auditsc.c
> > > > +++ b/kernel/auditsc.c
> > > > @@ -76,6 +76,7 @@
> > > > #include <linux/fsnotify_backend.h>
> > > > #include <uapi/linux/limits.h>
> > > > #include <uapi/linux/netfilter/nf_tables.h>
> > > > +#include <uapi/linux/openat2.h>
> > > >
> > > > #include "audit.h"
> > > >
> > > > @@ -196,6 +197,8 @@ static int audit_match_perm(struct audit_context *ctx, int mask)
> > > > return ((mask & AUDIT_PERM_WRITE) && ctx->argv[0] == SYS_BIND);
> > > > case AUDITSC_EXECVE:
> > > > return mask & AUDIT_PERM_EXEC;
> > > > + case AUDITSC_OPENAT2:
> > > > + return mask & ACC_MODE((u32)((struct open_how *)ctx->argv[2])->flags);
> > > > default:
> > > > return 0;
> > > > }
> > >
> > > ctx->argv[2] holds a userspace pointer and can't be dereferenced like this.
> > >
> > > I'm getting oopses, like so:
> > > BUG: unable to handle page fault for address: 00007fff961bbe70
> >
> > Thanks Jeff.
> >
> > Yes, this is obviously the wrong thing to being doing; I remember
> > checking to make sure we placed the audit_openat2_how() hook after the
> > open_how was copied from userspace, but I missed the argv dereference
> > in the syscall exit path when reviewing the code.
> >
> > Richard, as we are already copying the open_how info into
> > audit_context::openat2 safely, the obvious fix is to convert
> > audit_match_perm() to use the previously copied value instead of argv.
> > If you can't submit a patch for this today please let me know.
>
> I haven't heard anything from Richard so I put together a patch which
> should fix the problem (link below). It's currently untested, but
> I've got a kernel building now with the patch ...
Well, the day wasn't over yet... I've compiled and tested it.
> https://lore.kernel.org/linux-audit/164444111699.153511.15656610495968926251.stgit@olly/T/#u
>
> --
> paul-moore.com
>
- RGB
--
Richard Guy Briggs <rgb@redhat.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
next prev parent reply other threads:[~2022-02-09 22:14 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-19 20:00 [PATCH v4 0/3] audit: add support for openat2 Richard Guy Briggs
2021-05-19 20:00 ` [PATCH v4 1/3] audit: replace magic audit syscall class numbers with macros Richard Guy Briggs
2021-05-20 7:50 ` Christian Brauner
2021-08-05 22:01 ` Paul Moore
2021-05-19 20:00 ` [PATCH v4 2/3] audit: add support for the openat2 syscall Richard Guy Briggs
2021-05-20 7:58 ` Christian Brauner
2021-05-24 23:04 ` Paul Moore
2022-02-09 3:44 ` Jeff Mahoney
2022-02-09 15:57 ` Paul Moore
2022-02-09 21:18 ` Paul Moore
2022-02-09 22:13 ` Richard Guy Briggs [this message]
2022-02-09 22:31 ` Paul Moore
2022-02-09 21:40 ` Richard Guy Briggs
2022-02-09 22:29 ` Paul Moore
2021-05-19 20:00 ` [PATCH v4 3/3] audit: add OPENAT2 record to list how Richard Guy Briggs
2021-05-20 8:03 ` Christian Brauner
2021-05-24 23:08 ` Paul Moore
2021-05-25 15:00 ` Richard Guy Briggs
2021-10-04 16:08 ` Paul Moore
2021-10-04 18:27 ` Richard Guy Briggs
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20220209221352.GG1708086@madcap2.tricolour.ca \
--to=rgb@redhat.com \
--cc=eparis@parisplace.org \
--cc=eparis@redhat.com \
--cc=jeffm@suse.com \
--cc=linux-audit@redhat.com \
--cc=linux-fsdevel@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=paul@paul-moore.com \
--cc=sgrubb@redhat.com \
--cc=tonyj@suse.de \
--cc=viro@zeniv.linux.org.uk \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).