netdev - Re: [PATCH net v4 3/3] net: prevent address rewrite in kernel

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Message-ID: <CADKFtnTz-gDRKtDpw1p=AEkBSa3MispZDV8Rz5n+ZahdBr3vnA@mail.gmail.com>
Date: Thu, 21 Sep 2023 10:01:42 -0700
From: Jordan Rife <jrife@...gle.com>
To: Paolo Abeni <pabeni@...hat.com>
Cc: Willem de Bruijn <willemdebruijn.kernel@...il.com>, davem@...emloft.net, 
	edumazet@...gle.com, kuba@...nel.org, netdev@...r.kernel.org, 
	dborkman@...nel.org, philipp.reisner@...bit.com, lars.ellenberg@...bit.com, 
	christoph.boehmwalder@...bit.com, axboe@...nel.dk, airlied@...hat.com, 
	chengyou@...ux.alibaba.com, kaishen@...ux.alibaba.com, jgg@...pe.ca, 
	leon@...nel.org, bmt@...ich.ibm.com, isdn@...ux-pingi.de, ccaulfie@...hat.com, 
	teigland@...hat.com, mark@...heh.com, jlbec@...lplan.org, 
	joseph.qi@...ux.alibaba.com, sfrench@...ba.org, pc@...guebit.com, 
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	horms@...ge.net.au, ja@....bg, pablo@...filter.org, kadlec@...filter.org, 
	fw@...len.de, santosh.shilimkar@...cle.com, stable@...r.kernel.org
Subject: Re: [PATCH net v4 3/3] net: prevent address rewrite in kernel_bind()

On Thu, Sep 21, 2023 at 8:26 AM Paolo Abeni <pabeni@...hat.com> wrote:
>
> On Thu, 2023-09-21 at 09:30 -0400, Willem de Bruijn wrote:
> > On Thu, Sep 21, 2023 at 4:35 AM Paolo Abeni <pabeni@...hat.com> wrote:
> > >
> > > On Wed, 2023-09-20 at 09:30 -0400, Willem de Bruijn wrote:
> > > > Jordan Rife wrote:
> > > > > Similar to the change in commit 0bdf399342c5("net: Avoid address
> > > > > overwrite in kernel_connect"), BPF hooks run on bind may rewrite the
> > > > > address passed to kernel_bind(). This change
> > > > >
> > > > > 1) Makes a copy of the bind address in kernel_bind() to insulate
> > > > >    callers.
> > > > > 2) Replaces direct calls to sock->ops->bind() with kernel_bind()
> > > > >
> > > > > Link: https://lore.kernel.org/netdev/20230912013332.2048422-1-jrife@google.com/
> > > > > Fixes: 4fbac77d2d09 ("bpf: Hooks for sys_bind")
> > > > > Cc: stable@...r.kernel.org
> > > > > Signed-off-by: Jordan Rife <jrife@...gle.com>
> > > >
> > > > Reviewed-by: Willem de Bruijn <willemb@...gle.com>
> > >
> > > I fear this is going to cause a few conflicts with other trees. We can
> > > still take it, but at very least we will need some acks from the
> > > relevant maintainers.
> > >
> > > I *think* it would be easier split this and patch 1/3 in individual
> > > patches targeting the different trees, hopefully not many additional
> > > patches will be required. What do you think?
> >
> > Roughly how many patches would result from this one patch. From the
> > stat line I count { block/drbd, char/agp, infiniband, isdn, fs/dlm,
> > fs/ocfs2, fs/smb, netfilter, rds }. That's worst case nine callers
> > plus the core patch to net/socket.c?
>
> I think there should not be problems taking directly changes for rds
> and nf/ipvs.
>
> Additionally, I think the non network changes could consolidate the
> bind and connect changes in a single patch.
>
> It should be 7 not-network patches overall.
>
> > If logistically simpler and you prefer the approach, we can also
> > revisit Jordan's original approach, which embedded the memcpy inside
> > the BPF branches.
> >
> > That has the slight benefit to in-kernel callers that it limits the
> > cost of the memcpy to cgroup_bpf_enabled. But adds a superfluous
> > second copy to the more common userspace callers, again at least only
> > if cgroup_bpf_enabled.
> >
> > If so, it should at least move the whole logic around those BPF hooks
> > into helper functions.
>
> IMHO the approach implemented here is preferable, I suggest going
> forward with it.
>
> Thanks,
>
> Paolo
>

> Additionally, I think the non network changes could consolidate the
> bind and connect changes in a single patch.
>
> It should be 7 not-network patches overall.

I'm fine with this. If there are no objections, I can drop the non-net
changes in this patch series and send out several
kernel_connect/kernel_bind patches to the appropriate trees as a
follow up. Shall we wait to hear back from the maintainers or just go
ahead with this plan?

-Jordan