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Message-Id: <20200325055745.10710-4-joe@wand.net.nz>
Date: Tue, 24 Mar 2020 22:57:43 -0700
From: Joe Stringer <joe@...d.net.nz>
To: bpf@...r.kernel.org
Cc: netdev@...r.kernel.org, daniel@...earbox.net, ast@...nel.org,
eric.dumazet@...il.com, lmb@...udflare.com, kafai@...com
Subject: [PATCHv2 bpf-next 3/5] 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 or
dst_sk_prefetch.
Signed-off-by: Joe Stringer <joe@...d.net.nz>
---
v2: Initial version
---
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 2613d21a667a..1ca2e808cb8e 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -2533,15 +2533,23 @@ skb_sk_is_prefetched(struct sk_buff *skb)
return skb->destructor == sock_pfree;
}
-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;
}
--
2.20.1
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