From: Peter Oskolkov <posk@google.com>
To: David Ahern <dsahern@gmail.com>
Cc: Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
netdev <netdev@vger.kernel.org>, Peter Oskolkov <posk@posk.io>,
Willem de Bruijn <willemb@google.com>
Subject: Re: [PATCH bpf-next v10 5/7] bpf: add handling of BPF_LWT_REROUTE to lwt_bpf.c
Date: Wed, 13 Feb 2019 11:57:00 -0800 [thread overview]
Message-ID: <CAPNVh5eFMaXAdbhkn3Le5eQ-ZYaf2kWjKAxf4dfW9tYhyyXAKQ@mail.gmail.com> (raw)
In-Reply-To: <681aca28-b4e5-eb0d-46cd-94db7a2c368c@gmail.com>
On Tue, Feb 12, 2019 at 6:58 PM David Ahern <dsahern@gmail.com> wrote:
>
> On 2/12/19 10:32 AM, Peter Oskolkov wrote:
> > @@ -148,6 +174,87 @@ static int xmit_check_hhlen(struct sk_buff *skb)
> > return 0;
> > }
> >
> > +static int bpf_lwt_xmit_reroute(struct sk_buff *skb)
> > +{
> > + struct net_device *l3mdev = l3mdev_master_dev_rcu(skb_dst(skb)->dev);
> > + int oif = l3mdev ? l3mdev->ifindex : 0;
> > + struct dst_entry *dst = NULL;
> > + struct sock *sk;
> > + struct net *net;
> > + bool ipv4;
> > + int err;
> > +
> > + if (skb->protocol == htons(ETH_P_IP))
> > + ipv4 = true;
> > + else if (skb->protocol == htons(ETH_P_IPV6))
> > + ipv4 = false;
> > + else
> > + return -EAFNOSUPPORT;
> > +
> > + sk = sk_to_full_sk(skb->sk);
> > + if (sk) {
> > + if (sk->sk_bound_dev_if)
> > + oif = sk->sk_bound_dev_if;
> > + net = sock_net(sk);
> > + } else {
> > + net = dev_net(skb_dst(skb)->dev);
> > + }
> > +
> > + if (ipv4) {
> > + struct iphdr *iph = ip_hdr(skb);
> > + struct flowi4 fl4 = {};
> > + struct rtable *rt;
> > +
> > + fl4.flowi4_oif = oif;
> > + fl4.flowi4_mark = skb->mark;
> > + fl4.flowi4_uid = sock_net_uid(net, sk);
> > + fl4.flowi4_tos = RT_TOS(iph->tos);
> > + fl4.flowi4_flags = FLOWI_FLAG_ANYSRC;
> > + fl4.flowi4_proto = iph->protocol;
> > + fl4.daddr = iph->daddr;
> > + fl4.saddr = iph->saddr;
> > +
> > + rt = ip_route_output_key(net, &fl4);
> > + if (IS_ERR(rt) || rt->dst.error)
> > + return -EINVAL;
>
> I think you have a dst leak here if rt is valid but the lookup is a
> reject (e.g., unreachable or blackhole).
Thanks, David! I was not able to reproduce the leak, but based on your
suggestion and similar code elsewhere I made a change in v11 to explicitly
release a dst with error.
>
> > + dst = &rt->dst;
> > + } else {
> > + struct ipv6hdr *iph6 = ipv6_hdr(skb);
> > + struct flowi6 fl6 = {};
> > +
> > + fl6.flowi6_oif = oif;
> > + fl6.flowi6_mark = skb->mark;
> > + fl6.flowi6_uid = sock_net_uid(net, sk);
> > + fl6.flowlabel = ip6_flowinfo(iph6);
> > + fl6.flowi6_proto = iph6->nexthdr;
> > + fl6.daddr = iph6->daddr;
> > + fl6.saddr = iph6->saddr;
> > +
> > + err = ipv6_stub->ipv6_dst_lookup(net, skb->sk, &dst, &fl6);
> > + if (err || IS_ERR(dst) || dst->error)
> > + return -EINVAL;
>
> same here.
>
> You could check this by adding a route with unreachable as the target in
> your tests. Test cleanup and namespace teardown will tell you pretty quick.
next prev parent reply other threads:[~2019-02-13 19:57 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-12 17:32 [PATCH bpf-next v10 0/7] bpf: add BPF_LWT_ENCAP_IP option to bpf_lwt_push_encap Peter Oskolkov
2019-02-12 17:32 ` [PATCH bpf-next v10 1/7] bpf: add plumbing for BPF_LWT_ENCAP_IP in bpf_lwt_push_encap Peter Oskolkov
2019-02-12 17:32 ` [PATCH bpf-next v10 2/7] bpf: implement BPF_LWT_ENCAP_IP mode " Peter Oskolkov
2019-02-12 17:32 ` [PATCH bpf-next v10 3/7] bpf: handle GSO " Peter Oskolkov
2019-02-12 17:32 ` [PATCH bpf-next v10 4/7] ipv6_stub: add ipv6_route_input stub/proxy Peter Oskolkov
2019-02-12 17:32 ` [PATCH bpf-next v10 5/7] bpf: add handling of BPF_LWT_REROUTE to lwt_bpf.c Peter Oskolkov
2019-02-13 2:58 ` David Ahern
2019-02-13 19:57 ` Peter Oskolkov [this message]
2019-02-13 20:11 ` David Ahern
2019-02-13 20:41 ` Peter Oskolkov
2019-02-12 17:32 ` [PATCH bpf-next v10 6/7] bpf: sync <kdir>/include/.../bpf.h with tools/include/.../bpf.h Peter Oskolkov
2019-02-12 17:32 ` [PATCH bpf-next v10 7/7] selftests: bpf: add test_lwt_ip_encap selftest Peter Oskolkov
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=CAPNVh5eFMaXAdbhkn3Le5eQ-ZYaf2kWjKAxf4dfW9tYhyyXAKQ@mail.gmail.com \
--to=posk@google.com \
--cc=ast@kernel.org \
--cc=daniel@iogearbox.net \
--cc=dsahern@gmail.com \
--cc=netdev@vger.kernel.org \
--cc=posk@posk.io \
--cc=willemb@google.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).