From 71489e21d720a09388b565d60ef87ae993c10528 Mon Sep 17 00:00:00 2001 From: Joe Stringer Date: Sun, 29 Mar 2020 15:53:39 -0700 Subject: [PATCH] net: Track socket refcounts in skb_steal_sock() 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 Signed-off-by: Alexei Starovoitov Acked-by: Martin KaFai Lau Link: https://lore.kernel.org/bpf/20200329225342.16317-3-joe@wand.net.nz --- include/net/inet6_hashtables.h | 3 +-- include/net/inet_hashtables.h | 3 +-- include/net/sock.h | 10 +++++++++- net/ipv4/udp.c | 6 ++++-- net/ipv6/udp.c | 9 ++++++--- 5 files changed, 21 insertions(+), 10 deletions(-) diff --git a/include/net/inet6_hashtables.h b/include/net/inet6_hashtables.h index fe96bf247aac..81b965953036 100644 --- a/include/net/inet6_hashtables.h +++ b/include/net/inet6_hashtables.h @@ -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; diff --git a/include/net/inet_hashtables.h b/include/net/inet_hashtables.h index d0019d3395cf..ad64ba6a057f 100644 --- a/include/net/inet_hashtables.h +++ b/include/net/inet_hashtables.h @@ -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; diff --git a/include/net/sock.h b/include/net/sock.h index dc398cee7873..f81d528845f6 100644 --- a/include/net/sock.h +++ b/include/net/sock.h @@ -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; } diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c index 2633fc231593..b4035021bbd3 100644 --- a/net/ipv4/udp.c +++ b/net/ipv4/udp.c @@ -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; } diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c index 5dc439a391fe..7d4151747340 100644 --- a/net/ipv6/udp.c +++ b/net/ipv6/udp.c @@ -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; }