linux-kernel - Re: [PATCH ghak21 V2 3/4] audit: add refused symlink to audit

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Message-ID: <20180313101108.s6o7jec57rsxpsmc@madcap2.tricolour.ca>
Date:   Tue, 13 Mar 2018 06:11:08 -0400
From:   Richard Guy Briggs <rgb@...hat.com>
To:     Steve Grubb <sgrubb@...hat.com>
Cc:     Linux-Audit Mailing List <linux-audit@...hat.com>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH ghak21 V2 3/4] audit: add refused symlink to audit_names

On 2018-03-13 09:35, Steve Grubb wrote:
> On Mon, 12 Mar 2018 11:52:56 -0400
> Richard Guy Briggs <rgb@...hat.com> wrote:
> 
> > On 2018-03-12 11:53, Paul Moore wrote:
> > > On Mon, Mar 12, 2018 at 11:26 AM, Richard Guy Briggs
> > > <rgb@...hat.com> wrote:  
> > > > On 2018-03-12 11:12, Paul Moore wrote:  
> > > >> On Mon, Mar 12, 2018 at 2:31 AM, Richard Guy Briggs
> > > >> <rgb@...hat.com> wrote:  
> > > >> > Audit link denied events for symlinks had duplicate PATH
> > > >> > records rather than just updating the existing PATH record.
> > > >> > Update the symlink's PATH record with the current dentry and
> > > >> > inode information.
> > > >> >
> > > >> > See: https://github.com/linux-audit/audit-kernel/issues/21
> > > >> > Signed-off-by: Richard Guy Briggs <rgb@...hat.com>
> > > >> > ---
> > > >> >  fs/namei.c | 1 +
> > > >> >  1 file changed, 1 insertion(+)  
> > > >>
> > > >> Why didn't you include this in patch 4/4 like I asked during the
> > > >> previous review?  
> > > >
> > > > Please see the last comment of:
> > > > https://www.redhat.com/archives/linux-audit/2018-March/msg00070.html  
> > > 
> > > Yes, I just saw that ... I hadn't seen your replies on the v1
> > > patches until I had finished reviewing v2.  I just replied to that
> > > mail in the v1 thread, but basically you need to figure out what is
> > > necessary here and let us know.  If I have to figure it out it
> > > likely isn't going to get done with enough soak time prior to the
> > > upcoming merge window.  
> > 
> > Steve?  I was hoping you could chime in here.
> 
> If the CWD record will always be the same as the PARENT record, then we
> do not need the parent record. Duplicate information is bad. Like all
> the duplicate SYSCALL information.

The CWD record could be different from the PARENT record, since I could
have SYMLINK=/tmp/test/symlink, CWD=/tmp, PARENT=/tmp/test.  Does the
parent record even matter since it might not be a directory operation
like creat, unlink or rename?

> -Steve
> 
> > I'd just include it for completeness unless Steve thinks it will stand
> > on its own and doesn't want the overhead.
> > 
> > > >> > diff --git a/fs/namei.c b/fs/namei.c
> > > >> > index 50d2533..00f5041 100644
> > > >> > --- a/fs/namei.c
> > > >> > +++ b/fs/namei.c
> > > >> > @@ -945,6 +945,7 @@ static inline int may_follow_link(struct
> > > >> > nameidata *nd) if (nd->flags & LOOKUP_RCU)
> > > >> >                 return -ECHILD;
> > > >> >
> > > >> > +       audit_inode(nd->name, nd->stack[0].link.dentry, 0);
> > > >> >         audit_log_link_denied("follow_link",
> > > >> > &nd->stack[0].link); return -EACCES;
> > > >> >  }  
> > > >>
> > > >> paul moore  
> > > >
> > > > - RGB  
> > > 
> > > paul moore  
> > 
> > - RGB

- 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