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Message-ID: <1dd7175e-4906-6168-42e4-08715a292778@novek.ru>
Date: Mon, 19 Jul 2021 12:03:16 +0100
From: Vadim Fedorenko <vfedorenko@...ek.ru>
To: Xin Long <lucien.xin@...il.com>
Cc: David Ahern <dsahern@...nel.org>,
Willem de Bruijn <willemb@...gle.com>,
Paolo Abeni <pabeni@...hat.com>,
Jakub Kicinski <kuba@...nel.org>,
"David S. Miller" <davem@...emloft.net>,
network dev <netdev@...r.kernel.org>,
Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>,
Marcelo Ricardo Leitner <marcelo.leitner@...il.com>
Subject: Re: [PATCH net v2 1/2] udp: check encap socket in __udp_lib_err_encap
On 17.07.2021 19:41, Xin Long wrote:
> On Fri, Jul 16, 2021 at 6:32 PM Vadim Fedorenko <vfedorenko@...ek.ru> wrote:
>>
>> On 16.07.2021 19:46, Xin Long wrote:
>>> On Fri, Jul 16, 2021 at 6:54 AM Vadim Fedorenko <vfedorenko@...ek.ru> wrote:
>>>>
>>>> Commit d26796ae5894 ("udp: check udp sock encap_type in __udp_lib_err")
>>>> added checks for encapsulated sockets but it broke cases when there is
>>>> no implementation of encap_err_lookup for encapsulation, i.e. ESP in
>>>> UDP encapsulation. Fix it by calling encap_err_lookup only if socket
>>>> implements this method otherwise treat it as legal socket.
>>>>
>>>> Fixes: d26796ae5894 ("udp: check udp sock encap_type in __udp_lib_err")
>>>> Signed-off-by: Vadim Fedorenko <vfedorenko@...ek.ru>
>>>> ---
>>>> net/ipv4/udp.c | 23 +++++++++++++++++------
>>>> net/ipv6/udp.c | 23 +++++++++++++++++------
>>>> 2 files changed, 34 insertions(+), 12 deletions(-)
>>>>
>>>> diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
>>>> index 62cd4cd52e84..963275b94f00 100644
>>>> --- a/net/ipv4/udp.c
>>>> +++ b/net/ipv4/udp.c
>>>> @@ -645,10 +645,12 @@ static struct sock *__udp4_lib_err_encap(struct net *net,
>>>> const struct iphdr *iph,
>>>> struct udphdr *uh,
>>>> struct udp_table *udptable,
>>>> + struct sock *sk,
>>>> struct sk_buff *skb, u32 info)
>>>> {
>>>> + int (*lookup)(struct sock *sk, struct sk_buff *skb);
>>>> int network_offset, transport_offset;
>>>> - struct sock *sk;
>>>> + struct udp_sock *up;
>>>>
>>>> network_offset = skb_network_offset(skb);
>>>> transport_offset = skb_transport_offset(skb);
>>>> @@ -659,12 +661,19 @@ static struct sock *__udp4_lib_err_encap(struct net *net,
>>>> /* Transport header needs to point to the UDP header */
>>>> skb_set_transport_header(skb, iph->ihl << 2);
>>>>
>>>> + if (sk) {
>>>> + up = udp_sk(sk);
>>>> +
>>>> + lookup = READ_ONCE(up->encap_err_lookup);
>>>> + if (!lookup || !lookup(sk, skb))
>>>> + goto out;
>>>> + }
>>>> +
>>> Currently SCTP reuses lookup() to handle some of ICMP error packets by itself
>>> in lookup(), for these packets it will return 1, in which case we should
>>> set sk = NULL, and not let udp4_lib_err() handle these packets again.
>>>
>>> Can you change this part to this below?
>>>
>>> + if (sk) {
>>> + up = udp_sk(sk);
>>> +
>>> + lookup = READ_ONCE(up->encap_err_lookup);
>>> + if (lookup && lookup(sk, skb))
>>> + sk = NULL;
>>> +
>>> + goto out;
>>> + }
>>> +
>>>
>>> thanks.
>>>
>>
>> But we have vxlan and geneve with encap_err_lookup handler enabled and which do
>> not handle ICMP itself, just checks whether socket is correctly selected. Such
>> code could break their implementation
> Sorry, I don't see how this will break vxlan and geneve implementation.
>
> It checking 'sk' and calling lookup() here means we believe this sk
> should be the correct one (for the case of src == dst port only). So
> even if lookup() returns !0, we should NOT go to another
> __udp4_lib_lookup() in __udp4_lib_err_encap().
>
> If we don't believe this sk should be the correct one, as the sk was
> found with reverse ports, then we should NOT call lookup() with this sk
> but call __udp4_lib_lookup() directly in __udp4_lib_err_encap(), as it
> currently does, and fix this by checking READ_ONCE(up->encap_err_lookup)
> in __udp4_lib_lookup(), as Paolo suggested.
>
> Either way is fine to me, but not this one. what do you think?
>
> Thanks.
>
Ok, I got your point, will send v3 soon with what you suggested first.
Thanks for review!
>>
>>>> sk = __udp4_lib_lookup(net, iph->daddr, uh->source,
>>>> iph->saddr, uh->dest, skb->dev->ifindex, 0,
>>>> udptable, NULL);
>>>> if (sk) {
>>>> - int (*lookup)(struct sock *sk, struct sk_buff *skb);
>>>> - struct udp_sock *up = udp_sk(sk);
>>>> + up = udp_sk(sk);
>>>>
>>>> lookup = READ_ONCE(up->encap_err_lookup);
>>>> if (!lookup || lookup(sk, skb))
>>>> @@ -674,6 +683,7 @@ static struct sock *__udp4_lib_err_encap(struct net *net,
>>>> if (!sk)
>>>> sk = ERR_PTR(__udp4_lib_err_encap_no_sk(skb, info));
>>>>
>>>> +out:
>>>> skb_set_transport_header(skb, transport_offset);
>>>> skb_set_network_header(skb, network_offset);
>>>>
>>>> @@ -707,15 +717,16 @@ int __udp4_lib_err(struct sk_buff *skb, u32 info, struct udp_table *udptable)
>>>> sk = __udp4_lib_lookup(net, iph->daddr, uh->dest,
>>>> iph->saddr, uh->source, skb->dev->ifindex,
>>>> inet_sdif(skb), udptable, NULL);
>>>> +
>>>> if (!sk || udp_sk(sk)->encap_type) {
>>>> /* No socket for error: try tunnels before discarding */
>>>> - sk = ERR_PTR(-ENOENT);
>>>> if (static_branch_unlikely(&udp_encap_needed_key)) {
>>>> - sk = __udp4_lib_err_encap(net, iph, uh, udptable, skb,
>>>> + sk = __udp4_lib_err_encap(net, iph, uh, udptable, sk, skb,
>>>> info);
>>>> if (!sk)
>>>> return 0;
>>>> - }
>>>> + } else
>>>> + sk = ERR_PTR(-ENOENT);
>>>>
>>>> if (IS_ERR(sk)) {
>>>> __ICMP_INC_STATS(net, ICMP_MIB_INERRORS);
>>>> diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
>>>> index 0cc7ba531b34..0210ec93d21d 100644
>>>> --- a/net/ipv6/udp.c
>>>> +++ b/net/ipv6/udp.c
>>>> @@ -502,12 +502,14 @@ static struct sock *__udp6_lib_err_encap(struct net *net,
>>>> const struct ipv6hdr *hdr, int offset,
>>>> struct udphdr *uh,
>>>> struct udp_table *udptable,
>>>> + struct sock *sk,
>>>> struct sk_buff *skb,
>>>> struct inet6_skb_parm *opt,
>>>> u8 type, u8 code, __be32 info)
>>>> {
>>>> + int (*lookup)(struct sock *sk, struct sk_buff *skb);
>>>> int network_offset, transport_offset;
>>>> - struct sock *sk;
>>>> + struct udp_sock *up;
>>>>
>>>> network_offset = skb_network_offset(skb);
>>>> transport_offset = skb_transport_offset(skb);
>>>> @@ -518,12 +520,19 @@ static struct sock *__udp6_lib_err_encap(struct net *net,
>>>> /* Transport header needs to point to the UDP header */
>>>> skb_set_transport_header(skb, offset);
>>>>
>>>> + if (sk) {
>>>> + up = udp_sk(sk);
>>>> +
>>>> + lookup = READ_ONCE(up->encap_err_lookup);
>>>> + if (!lookup || !lookup(sk, skb))
>>>> + goto out;
>>>> + }
>>>> +
>>>> sk = __udp6_lib_lookup(net, &hdr->daddr, uh->source,
>>>> &hdr->saddr, uh->dest,
>>>> inet6_iif(skb), 0, udptable, skb);
>>>> if (sk) {
>>>> - int (*lookup)(struct sock *sk, struct sk_buff *skb);
>>>> - struct udp_sock *up = udp_sk(sk);
>>>> + up = udp_sk(sk);
>>>>
>>>> lookup = READ_ONCE(up->encap_err_lookup);
>>>> if (!lookup || lookup(sk, skb))
>>>> @@ -535,6 +544,7 @@ static struct sock *__udp6_lib_err_encap(struct net *net,
>>>> offset, info));
>>>> }
>>>>
>>>> +out:
>>>> skb_set_transport_header(skb, transport_offset);
>>>> skb_set_network_header(skb, network_offset);
>>>>
>>>> @@ -558,16 +568,17 @@ int __udp6_lib_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
>>>>
>>>> sk = __udp6_lib_lookup(net, daddr, uh->dest, saddr, uh->source,
>>>> inet6_iif(skb), inet6_sdif(skb), udptable, NULL);
>>>> +
>>>> if (!sk || udp_sk(sk)->encap_type) {
>>>> /* No socket for error: try tunnels before discarding */
>>>> - sk = ERR_PTR(-ENOENT);
>>>> if (static_branch_unlikely(&udpv6_encap_needed_key)) {
>>>> sk = __udp6_lib_err_encap(net, hdr, offset, uh,
>>>> - udptable, skb,
>>>> + udptable, sk, skb,
>>>> opt, type, code, info);
>>>> if (!sk)
>>>> return 0;
>>>> - }
>>>> + } else
>>>> + sk = ERR_PTR(-ENOENT);
>>>>
>>>> if (IS_ERR(sk)) {
>>>> __ICMP6_INC_STATS(net, __in6_dev_get(skb->dev),
>>>> --
>>>> 2.18.4
>>>>
>>
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