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Date: Tue, 26 Apr 2022 16:07:08 +0800
From: menglong8.dong@...il.com
To: kuba@...nel.org
Cc: rostedt@...dmis.org, mingo@...hat.com, davem@...emloft.net,
yoshfuji@...ux-ipv6.org, dsahern@...nel.org, pabeni@...hat.com,
benbjiang@...cent.com, flyingpeng@...cent.com,
imagedong@...cent.com, edumazet@...gle.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 1/2] net: add skb drop reasons to inet connect request
From: Menglong Dong <imagedong@...cent.com>
The 'conn_request()' in struct inet_connection_sock_af_ops is used to
process connection requesting for TCP/DCCP. Take TCP for example, it
is just 'tcp_v4_conn_request()'.
When non-zero value is returned by 'tcp_v4_conn_request()', the skb
will be freed by kfree_skb() and a 'reset' packet will be send.
Otherwise, it will be freed normally.
In this code path, 'consume_skb()' is used in many abnormal cases, such
as the accept queue of the listen socket full, which should be
'kfree_skb()'.
Therefore, we make a little change to the 'conn_request()' interface.
When 0 is returned, we call 'consume_skb()' as usual; when negative is
returned, we call 'kfree_skb()' and send a 'reset' as usual; when
positive is returned, which has not happened yet, we do nothing, and
skb will be freed in 'conn_request()'. Then, we can use drop reasons
in 'conn_request()'.
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>
---
include/linux/skbuff.h | 4 ++++
include/trace/events/skb.h | 2 ++
net/dccp/input.c | 12 +++++-------
net/ipv4/tcp_input.c | 21 +++++++++++++--------
net/ipv4/tcp_ipv4.c | 3 ++-
5 files changed, 26 insertions(+), 16 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/dccp/input.c b/net/dccp/input.c
index 2cbb757a894f..ed20dfe83f66 100644
--- a/net/dccp/input.c
+++ b/net/dccp/input.c
@@ -574,8 +574,7 @@ int dccp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
struct dccp_sock *dp = dccp_sk(sk);
struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb);
const int old_state = sk->sk_state;
- bool acceptable;
- int queued = 0;
+ int err, queued = 0;
/*
* Step 3: Process LISTEN state
@@ -606,13 +605,12 @@ int dccp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
*/
rcu_read_lock();
local_bh_disable();
- acceptable = inet_csk(sk)->icsk_af_ops->conn_request(sk, skb) >= 0;
+ err = inet_csk(sk)->icsk_af_ops->conn_request(sk, skb);
local_bh_enable();
rcu_read_unlock();
- if (!acceptable)
- return 1;
- consume_skb(skb);
- return 0;
+ if (!err)
+ consume_skb(skb);
+ return err < 0;
}
if (dh->dccph_type == DCCP_PKT_RESET)
goto discard;
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index daff631b9486..e0bbbd624246 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);
@@ -6438,14 +6438,13 @@ 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)
- return 1;
- consume_skb(skb);
- return 0;
+ if (!err)
+ consume_skb(skb);
+ return err < 0;
}
SKB_DR_SET(reason, TCP_FLAGS);
goto discard;
@@ -6878,6 +6877,7 @@ 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 +6886,15 @@ 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 +6950,7 @@ 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;
}
@@ -7006,7 +7010,8 @@ int tcp_conn_request(struct request_sock_ops *rsk_ops,
drop_and_free:
__reqsk_free(req);
drop:
+ kfree_skb_reason(skb, reason);
tcp_listendrop(sk);
- return 0;
+ return 1;
}
EXPORT_SYMBOL(tcp_conn_request);
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 157265aecbed..b8daf49f54a5 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -1470,7 +1470,8 @@ int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb)
drop:
tcp_listendrop(sk);
- return 0;
+ kfree_skb_reason(skb, SKB_DROP_REASON_IP_INADDRERRORS);
+ return 1;
}
EXPORT_SYMBOL(tcp_v4_conn_request);
--
2.36.0
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