From: Paul Moore <paul@paul-moore.com>
To: Richard Guy Briggs <rgb@redhat.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 17:31:38 -0500 [thread overview]
Message-ID: <CAHC9VhRn7MGRqww2M28i8eD_EK3-OVtyqiMeT72Y7N_=f0MM9w@mail.gmail.com> (raw)
In-Reply-To: <20220209221352.GG1708086@madcap2.tricolour.ca>
On Wed, Feb 9, 2022 at 5:14 PM Richard Guy Briggs <rgb@redhat.com> wrote:
>
> 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.
Yes, I tested my patch too and everything looks good on my end.
For future reference, while I didn't explicitly ask you to acknowledge
this thread and that you were working on a patch (I probably should
have), it would have been nice if you could have sent a quick note to
the list.
--
paul-moore.com
next prev parent reply other threads:[~2022-02-09 22:32 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
2022-02-09 22:31 ` Paul Moore [this message]
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
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