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Date: Fri, 16 Jul 2021 14:46:16 -0400
From: Xin Long <lucien.xin@...il.com>
To: Vadim Fedorenko <vfedorenko@...ek.ru>
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 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.
> 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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