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Date: Thu, 28 Apr 2022 15:33:39 +0800
From: menglong8.dong@...il.com
To: edumazet@...gle.com
Cc: rostedt@...dmis.org, mingo@...hat.com, davem@...emloft.net,
yoshfuji@...ux-ipv6.org, dsahern@...nel.org, kuba@...nel.org,
pabeni@...hat.com, benbjiang@...cent.com, flyingpeng@...cent.com,
imagedong@...cent.com, kafai@...com, talalahmad@...gle.com,
keescook@...omium.org, mengensun@...cent.com,
dongli.zhang@...cle.com, linux-kernel@...r.kernel.org,
netdev@...r.kernel.org
Subject: [PATCH net-next v2 1/2] net: tcp: add skb drop reasons to tcp connect request
From: Menglong Dong <imagedong@...cent.com>
For now, the return value of tcp_v4_conn_request() has the following
means:
>=0: the skb is acceptable, free it with consume_skb()
<0 : the skb is unacceptable, free it with kfree_skb() and send a
RESET
In order to get the drop reasons from tcp_v4_conn_request(), we make
some changes to its return value:
==0: the skb is acceptable, free it with consume_skb()
>0: the return value is exactly the skb drop reasons, free it with
kfree_skb_reason() without sendind RESET
<0: the same as what we do before
( As a negative value can be returned by
struct inet_connection_sock_af_ops.conn_request(), so we can't make
the return value of tcp_v4_conn_request() as num skb_drop_reason
directly. )
Therefore, previous logic is not changed, as tcp_v4_conn_request()
never return a positive before.
With drop reasons returned, the caller of tcp_v4_conn_request(), which
is tcp_rcv_state_process(), will call kfree_skb_reason() instead of
consume_skb().
Following new drop reasons are added:
SKB_DROP_REASON_LISTENOVERFLOWS
SKB_DROP_REASON_TCP_REQQFULLDROP
Reviewed-by: Jiang Biao <benbjiang@...cent.com>
Reviewed-by: Hao Peng <flyingpeng@...cent.com>
Signed-off-by: Menglong Dong <imagedong@...cent.com>
---
v2:
- don't free skb in conn_request, as Eric suggested, and use it's
return value to pass drop reasons.
---
include/linux/skbuff.h | 4 ++++
include/trace/events/skb.h | 2 ++
net/ipv4/tcp_input.c | 20 ++++++++++++++------
net/ipv4/tcp_ipv4.c | 2 +-
net/ipv6/tcp_ipv6.c | 4 ++--
5 files changed, 23 insertions(+), 9 deletions(-)
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 84d78df60453..f33b3636bbce 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -469,6 +469,10 @@ enum skb_drop_reason {
SKB_DROP_REASON_PKT_TOO_BIG, /* packet size is too big (maybe exceed
* the MTU)
*/
+ SKB_DROP_REASON_LISTENOVERFLOWS, /* accept queue of the listen socket is full */
+ SKB_DROP_REASON_TCP_REQQFULLDROP, /* request queue of the listen
+ * socket is full
+ */
SKB_DROP_REASON_MAX,
};
diff --git a/include/trace/events/skb.h b/include/trace/events/skb.h
index a477bf907498..de6c93670437 100644
--- a/include/trace/events/skb.h
+++ b/include/trace/events/skb.h
@@ -80,6 +80,8 @@
EM(SKB_DROP_REASON_IP_INADDRERRORS, IP_INADDRERRORS) \
EM(SKB_DROP_REASON_IP_INNOROUTES, IP_INNOROUTES) \
EM(SKB_DROP_REASON_PKT_TOO_BIG, PKT_TOO_BIG) \
+ EM(SKB_DROP_REASON_LISTENOVERFLOWS, LISTENOVERFLOWS) \
+ EM(SKB_DROP_REASON_TCP_REQQFULLDROP, TCP_REQQFULLDROP) \
EMe(SKB_DROP_REASON_MAX, MAX)
#undef EM
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index daff631b9486..412367b7dfd6 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -6411,7 +6411,7 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb)
struct inet_connection_sock *icsk = inet_csk(sk);
const struct tcphdr *th = tcp_hdr(skb);
struct request_sock *req;
- int queued = 0;
+ int err, queued = 0;
bool acceptable;
SKB_DR(reason);
@@ -6438,13 +6438,16 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb)
*/
rcu_read_lock();
local_bh_disable();
- acceptable = icsk->icsk_af_ops->conn_request(sk, skb) >= 0;
+ err = icsk->icsk_af_ops->conn_request(sk, skb);
local_bh_enable();
rcu_read_unlock();
- if (!acceptable)
+ if (err < 0)
return 1;
- consume_skb(skb);
+ if (err)
+ kfree_skb_reason(skb, err);
+ else
+ consume_skb(skb);
return 0;
}
SKB_DR_SET(reason, TCP_FLAGS);
@@ -6878,6 +6881,7 @@ int tcp_conn_request(struct request_sock_ops *rsk_ops,
bool want_cookie = false;
struct dst_entry *dst;
struct flowi fl;
+ SKB_DR(reason);
/* TW buckets are converted to open requests without
* limitations, they conserve resources and peer is
@@ -6886,12 +6890,15 @@ int tcp_conn_request(struct request_sock_ops *rsk_ops,
if ((net->ipv4.sysctl_tcp_syncookies == 2 ||
inet_csk_reqsk_queue_is_full(sk)) && !isn) {
want_cookie = tcp_syn_flood_action(sk, rsk_ops->slab_name);
- if (!want_cookie)
+ if (!want_cookie) {
+ SKB_DR_SET(reason, TCP_REQQFULLDROP);
goto drop;
+ }
}
if (sk_acceptq_is_full(sk)) {
NET_INC_STATS(sock_net(sk), LINUX_MIB_LISTENOVERFLOWS);
+ SKB_DR_SET(reason, LISTENOVERFLOWS);
goto drop;
}
@@ -6947,6 +6954,7 @@ int tcp_conn_request(struct request_sock_ops *rsk_ops,
*/
pr_drop_req(req, ntohs(tcp_hdr(skb)->source),
rsk_ops->family);
+ SKB_DR_SET(reason, TCP_REQQFULLDROP);
goto drop_and_release;
}
@@ -7007,6 +7015,6 @@ int tcp_conn_request(struct request_sock_ops *rsk_ops,
__reqsk_free(req);
drop:
tcp_listendrop(sk);
- return 0;
+ return reason;
}
EXPORT_SYMBOL(tcp_conn_request);
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 157265aecbed..6a49470d30db 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -1470,7 +1470,7 @@ int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb)
drop:
tcp_listendrop(sk);
- return 0;
+ return SKB_DROP_REASON_IP_INADDRERRORS;
}
EXPORT_SYMBOL(tcp_v4_conn_request);
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 782df529ff69..92f4a58fdc2c 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -1158,7 +1158,7 @@ static int tcp_v6_conn_request(struct sock *sk, struct sk_buff *skb)
if (ipv6_addr_v4mapped(&ipv6_hdr(skb)->saddr)) {
__IP6_INC_STATS(sock_net(sk), NULL, IPSTATS_MIB_INHDRERRORS);
- return 0;
+ return SKB_DROP_REASON_IP_INADDRERRORS;
}
return tcp_conn_request(&tcp6_request_sock_ops,
@@ -1166,7 +1166,7 @@ static int tcp_v6_conn_request(struct sock *sk, struct sk_buff *skb)
drop:
tcp_listendrop(sk);
- return 0; /* don't send reset */
+ return SKB_DROP_REASON_IP_INADDRERRORS; /* don't send reset */
}
static void tcp_v6_restore_cb(struct sk_buff *skb)
--
2.36.0
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