netdev - Re: [PATCH ipsec-next v10 2/3] xfrm: Add dir validation to "out" data path lookup

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Message-ID: <ZiWPcIbrekFDzsAE@moon.secunet.de>
Date: Mon, 22 Apr 2024 00:13:04 +0200
From: Antony Antony <antony.antony@...unet.com>
To: Simon Horman <horms@...nel.org>
CC: Antony Antony <antony.antony@...unet.com>, Steffen Klassert
	<steffen.klassert@...unet.com>, Herbert Xu <herbert@...dor.apana.org.au>,
	<netdev@...r.kernel.org>, "David S. Miller" <davem@...emloft.net>, "Eric
 Dumazet" <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, Paolo Abeni
	<pabeni@...hat.com>, <devel@...ux-ipsec.org>, Leon Romanovsky
	<leon@...nel.org>, Eyal Birger <eyal.birger@...il.com>, Nicolas Dichtel
	<nicolas.dichtel@...nd.com>, Sabrina Dubroca <sd@...asysnail.net>
Subject: Re: [PATCH ipsec-next v10 2/3] xfrm: Add dir validation to "out"
 data path lookup

Hi Simon,

On Thu, Apr 18, 2024 at 10:24:21 +0100, Simon Horman wrote:
> On Thu, Apr 11, 2024 at 11:42:13AM +0200, Antony Antony wrote:
> > Introduces validation for the x->dir attribute within the XFRM output
> > data lookup path. If the configured direction does not match the expected
> > direction, out, increment the XfrmOutDirError counter and drop the packet
> > to ensure data integrity and correct flow handling.
> > 
> > grep -vw 0 /proc/net/xfrm_stat
> > XfrmOutPolError         	2
> > XfrmOutDirError         	2
> > 
> > Signed-off-by: Antony Antony <antony.antony@...unet.com>
> 
> ...
> 
> > diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c
> > index 6affe5cd85d8..7deeb21dae15 100644
> > --- a/net/xfrm/xfrm_policy.c
> > +++ b/net/xfrm/xfrm_policy.c
> > @@ -2489,6 +2489,12 @@ xfrm_tmpl_resolve_one(struct xfrm_policy *policy, const struct flowi *fl,
> >  
> >  		x = xfrm_state_find(remote, local, fl, tmpl, policy, &error,
> >  				    family, policy->if_id);
> > +		if (x->dir && x->dir != XFRM_SA_DIR_OUT) {
> > +			XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTDIRERROR);
> > +			xfrm_state_put(x);
> > +			error = -EINVAL;
> > +			goto fail;
> > +		}
> 
> Hi Antony,
> 
> the line below assumes that x may be NULL,
> but the new code above dereferences x unconditionally.
> Is this ok?

probably not. I added a fix in v11.


> 
> Flagged by Smatch.

thanks.

> 
> >  
> >  		if (x && x->km.state == XFRM_STATE_VALID) {
> >  			xfrm[nx++] = x;
> 
> ...