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net: Track socket refcounts in skb_steal_sock()

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Refactor the UDP/TCP handlers slightly to allow skb_steal_sock() to make
the determination of whether the socket is reference counted in the case
where it is prefetched by earlier logic such as early_demux.

Signed-off-by: Joe Stringer <joe@wand.net.nz>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20200329225342.16317-3-joe@wand.net.nz
This commit is contained in:
Joe Stringer 2020-03-29 15:53:39 -07:00 committed by Alexei Starovoitov
parent cf7fbe660f
commit 71489e21d7
5 changed files with 21 additions and 10 deletions
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3
include/net/inet6_hashtables.h
View File

@ -85,9 +85,8 @@ static inline struct sock *__inet6_lookup_skb(struct inet_hashinfo *hashinfo,
int iif, int sdif,
bool *refcounted)
{
struct sock *sk = skb_steal_sock(skb);
struct sock *sk = skb_steal_sock(skb, refcounted);
*refcounted = true;
if (sk)
return sk;

3
include/net/inet_hashtables.h
View File

@ -379,10 +379,9 @@ static inline struct sock *__inet_lookup_skb(struct inet_hashinfo *hashinfo,
const int sdif,
bool *refcounted)
{
struct sock *sk = skb_steal_sock(skb);
struct sock *sk = skb_steal_sock(skb, refcounted);
const struct iphdr *iph = ip_hdr(skb);
*refcounted = true;
if (sk)
return sk;

10
include/net/sock.h
View File

@ -2537,15 +2537,23 @@ skb_sk_is_prefetched(struct sk_buff *skb)
#endif /* CONFIG_INET */
}
static inline struct sock *skb_steal_sock(struct sk_buff *skb)
/**
* skb_steal_sock
* @skb to steal the socket from
* @refcounted is set to true if the socket is reference-counted
*/
static inline struct sock *
skb_steal_sock(struct sk_buff *skb, bool *refcounted)
{
if (skb->sk) {
struct sock *sk = skb->sk;
*refcounted = true;
skb->destructor = NULL;
skb->sk = NULL;
return sk;
}
*refcounted = false;
return NULL;
}

6
net/ipv4/udp.c
View File

@ -2288,6 +2288,7 @@ int __udp4_lib_rcv(struct sk_buff *skb, struct udp_table *udptable,
struct rtable *rt = skb_rtable(skb);
__be32 saddr, daddr;
struct net *net = dev_net(skb->dev);
bool refcounted;
/*
* Validate the packet.
@ -2313,7 +2314,7 @@ int __udp4_lib_rcv(struct sk_buff *skb, struct udp_table *udptable,
if (udp4_csum_init(skb, uh, proto))
goto csum_error;
sk = skb_steal_sock(skb);
sk = skb_steal_sock(skb, &refcounted);
if (sk) {
struct dst_entry *dst = skb_dst(skb);
int ret;
@ -2322,7 +2323,8 @@ int __udp4_lib_rcv(struct sk_buff *skb, struct udp_table *udptable,
udp_sk_rx_dst_set(sk, dst);
ret = udp_unicast_rcv_skb(sk, skb, uh);
sock_put(sk);
if (refcounted)
sock_put(sk);
return ret;
}

9
net/ipv6/udp.c
View File

@ -843,6 +843,7 @@ int __udp6_lib_rcv(struct sk_buff *skb, struct udp_table *udptable,
struct net *net = dev_net(skb->dev);
struct udphdr *uh;
struct sock *sk;
bool refcounted;
u32 ulen = 0;
if (!pskb_may_pull(skb, sizeof(struct udphdr)))
@ -879,7 +880,7 @@ int __udp6_lib_rcv(struct sk_buff *skb, struct udp_table *udptable,
goto csum_error;
/* Check if the socket is already available, e.g. due to early demux */
sk = skb_steal_sock(skb);
sk = skb_steal_sock(skb, &refcounted);
if (sk) {
struct dst_entry *dst = skb_dst(skb);
int ret;
@ -888,12 +889,14 @@ int __udp6_lib_rcv(struct sk_buff *skb, struct udp_table *udptable,
udp6_sk_rx_dst_set(sk, dst);
if (!uh->check && !udp_sk(sk)->no_check6_rx) {
sock_put(sk);
if (refcounted)
sock_put(sk);
goto report_csum_error;
}
ret = udp6_unicast_rcv_skb(sk, skb, uh);
sock_put(sk);
if (refcounted)
sock_put(sk);
return ret;
}