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[192.55.54.39]) by smtp.gmail.com with ESMTPSA id m20sm24540054pfj.142.2019.03.08.02.00.02 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Fri, 08 Mar 2019 02:00:05 -0800 (PST) Date: Fri, 8 Mar 2019 10:59:44 +0100 From: Maciej Fijalkowski To: =?ISO-8859-1?Q?Bj=F6rn_T=F6pel?= Cc: ast@kernel.org, daniel@iogearbox.net, netdev@vger.kernel.org, =?ISO-8859-1?Q?Bj=F6rn_T=F6pel?= , magnus.karlsson@intel.com, magnus.karlsson@gmail.com, bpf@vger.kernel.org Subject: Re: [PATCH bpf 1/2] xsk: fix to reject invalid flags in xsk_bind Message-ID: <20190308105907.00000518@gmail.com> In-Reply-To: <20190308075727.19358-2-bjorn.topel@gmail.com> References: <20190308075727.19358-1-bjorn.topel@gmail.com> <20190308075727.19358-2-bjorn.topel@gmail.com> X-Mailer: Claws Mail 3.17.1 (GTK+ 2.24.32; x86_64-w64-mingw32) MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Sender: bpf-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org On Fri, 8 Mar 2019 08:57:26 +0100 Bj=F6rn T=F6pel wrote: > From: Bj=F6rn T=F6pel >=20 > Passing a non-existing flag in the sxdp_flags member of struct > sockaddr_xdp was, incorrectly, silently ignored. This patch addresses > that behavior, and rejects any non-existing flags. >=20 > We have examined existing user space code, and to our best knowledge, > no one is relying on the current incorrect behavior. AF_XDP is still > in its infancy, so from our perspective, the risk of breakage is very > low, and addressing this problem now is important. >=20 > Fixes: 965a99098443 ("xsk: add support for bind for Rx") > Signed-off-by: Bj=F6rn T=F6pel > --- > net/xdp/xsk.c | 5 ++++- > 1 file changed, 4 insertions(+), 1 deletion(-) >=20 > diff --git a/net/xdp/xsk.c b/net/xdp/xsk.c > index 6697084e3fdf..a14e8864e4fa 100644 > --- a/net/xdp/xsk.c > +++ b/net/xdp/xsk.c > @@ -407,6 +407,10 @@ static int xsk_bind(struct socket *sock, struct sock= addr *addr, int addr_len) > if (sxdp->sxdp_family !=3D AF_XDP) > return -EINVAL; > =20 > + flags =3D sxdp->sxdp_flags; > + if (flags & ~(XDP_SHARED_UMEM | XDP_COPY | XDP_ZEROCOPY)) > + return -EINVAL; > + What about setting more than one flag at a time? Is it allowed/make any sen= se? After a quick look it seems that they exclude each other, e.g. you can't fo= rce a zero copy and copy mode at the same time. And for XDP_SHARED_UMEM two remaining flags can't be set. So maybe check here also that only one particular flag is set by doing: if (hweight32(flags & (XDP_SHARED_UMEM | XDP_COPY | XDP_ZEROCOPY)) > 1) return -EINVAL; just like we do it for IFLA_XDP_FLAGS in net/core/rtnetlink.c? > mutex_lock(&xs->mutex); > if (xs->dev) { > err =3D -EBUSY; > @@ -425,7 +429,6 @@ static int xsk_bind(struct socket *sock, struct socka= ddr *addr, int addr_len) > } > =20 > qid =3D sxdp->sxdp_queue_id; > - flags =3D sxdp->sxdp_flags; > =20 > if (flags & XDP_SHARED_UMEM) { > struct xdp_sock *umem_xs;