[PATCH net-next 6/9] net: tcp: make tcp_rcv_state_process() return drop reason

menglong8.dong
2022-05-16T03:47:02Z

For now, the return value of tcp_rcv_state_process() is treated as bool.
Therefore, we can make it return the reasons of the skb drops.

Meanwhile, the return value of tcp_child_process() comes from
tcp_rcv_state_process(), make it drop reasons by the way.

Signed-off-by: Menglong Dong <imagedong@tencent.com>
---
include/linux/skbuff.h | 1 +
include/net/tcp.h | 8 +++++---
net/ipv4/tcp_input.c | 22 +++++++++++-----------
net/ipv4/tcp_ipv4.c | 20 +++++++++++++-------
net/ipv4/tcp_minisocks.c | 11 ++++++-----
net/ipv6/tcp_ipv6.c | 19 ++++++++++++-------
6 files changed, 48 insertions(+), 33 deletions(-)

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 36e0971f4cc9..736899cc6a13 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -620,6 +620,7 @@ struct sk_buff;
FN(PKT_TOO_BIG) \
FN(SOCKET_DESTROYED) \
FN(TCP_PAWSACTIVEREJECTED) \
+ FN(TCP_ABORTONDATA) \
FN(MAX)

/* The reason of skb drop, which is used in kfree_skb_reason().
diff --git a/include/net/tcp.h b/include/net/tcp.h
index 1e99f5c61f84..ea0eb2d4a743 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -339,7 +339,8 @@ void tcp_wfree(struct sk_buff *skb);
void tcp_write_timer_handler(struct sock *sk);
void tcp_delack_timer_handler(struct sock *sk);
int tcp_ioctl(struct sock *sk, int cmd, unsigned long arg);
-int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb);
+enum skb_drop_reason tcp_rcv_state_process(struct sock *sk,
+ struct sk_buff *skb);
void tcp_rcv_established(struct sock *sk, struct sk_buff *skb);
void tcp_rcv_space_adjust(struct sock *sk);
int tcp_twsk_unique(struct sock *sk, struct sock *sktw, void *twp);
@@ -385,8 +386,9 @@ enum tcp_tw_status tcp_timewait_state_process(struct inet_timewait_sock *tw,
struct sock *tcp_check_req(struct sock *sk, struct sk_buff *skb,
struct request_sock *req, bool fastopen,
bool *lost_race);
-int tcp_child_process(struct sock *parent, struct sock *child,
- struct sk_buff *skb);
+enum skb_drop_reason tcp_child_process(struct sock *parent,
+ struct sock *child,
+ struct sk_buff *skb);
void tcp_enter_loss(struct sock *sk);
void tcp_cwnd_reduction(struct sock *sk, int newly_acked_sacked, int newly_lost, int flag);
void tcp_clear_retrans(struct tcp_sock *tp);
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index e8d26a68bc45..4717af0eaea7 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -6422,7 +6422,7 @@ static void tcp_rcv_synrecv_state_fastopen(struct sock *sk)
* address independent.
*/

-int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb)
+enum skb_drop_reason tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb)
{
struct tcp_sock *tp = tcp_sk(sk);
struct inet_connection_sock *icsk = inet_csk(sk);
@@ -6439,7 +6439,7 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb)

case TCP_LISTEN:
if (th->ack)
- return 1;
+ return SKB_DROP_REASON_TCP_FLAGS;

if (th->rst) {
SKB_DR_SET(reason, TCP_RESET);
@@ -6460,9 +6460,9 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb)
rcu_read_unlock();

if (!acceptable)
- return 1;
+ return SKB_DROP_REASON_NOT_SPECIFIED;
consume_skb(skb);
- return 0;
+ return SKB_NOT_DROPPED_YET;
}
SKB_DR_SET(reason, TCP_FLAGS);
goto discard;
@@ -6472,13 +6472,13 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb)
tcp_mstamp_refresh(tp);
queued = tcp_rcv_synsent_state_process(sk, skb, th);
if (queued >= 0)
- return queued;
+ return (enum skb_drop_reason)queued;

/* Do step6 onward by hand. */
tcp_urg(sk, skb, th);
__kfree_skb(skb);
tcp_data_snd_check(sk);
- return 0;
+ return SKB_NOT_DROPPED_YET;
}

tcp_mstamp_refresh(tp);
@@ -6582,7 +6582,7 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb)
if (tp->linger2 < 0) {
tcp_done(sk);
NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPABORTONDATA);
- return 1;
+ return SKB_DROP_REASON_TCP_ABORTONDATA;
}
if (TCP_SKB_CB(skb)->end_seq != TCP_SKB_CB(skb)->seq &&
after(TCP_SKB_CB(skb)->end_seq - th->fin, tp->rcv_nxt)) {
@@ -6591,7 +6591,7 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb)
tcp_fastopen_active_disable(sk);
tcp_done(sk);
NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPABORTONDATA);
- return 1;
+ return SKB_DROP_REASON_TCP_ABORTONDATA;
}

tmo = tcp_fin_time(sk);
@@ -6656,7 +6656,7 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb)
after(TCP_SKB_CB(skb)->end_seq - th->fin, tp->rcv_nxt)) {
NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPABORTONDATA);
tcp_reset(sk, skb);
- return 1;
+ return SKB_DROP_REASON_TCP_ABORTONDATA;
}
}
fallthrough;
@@ -6676,11 +6676,11 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb)
discard:
tcp_drop_reason(sk, skb, reason);
}
- return 0;
+ return SKB_NOT_DROPPED_YET;

consume:
__kfree_skb(skb);
- return 0;
+ return SKB_NOT_DROPPED_YET;
}
EXPORT_SYMBOL(tcp_rcv_state_process);

diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 24eb42497a71..12a18c5035f4 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -1670,7 +1670,8 @@ int tcp_v4_do_rcv(struct sock *sk, struct sk_buff *skb)
if (!nsk)
goto discard;
if (nsk != sk) {
- if (tcp_child_process(sk, nsk, skb)) {
+ reason = tcp_child_process(sk, nsk, skb);
+ if (reason) {
rsk = nsk;
goto reset;
}
@@ -1679,7 +1680,8 @@ int tcp_v4_do_rcv(struct sock *sk, struct sk_buff *skb)
} else
sock_rps_save_rxhash(sk, skb);

- if (tcp_rcv_state_process(sk, skb)) {
+ reason = tcp_rcv_state_process(sk, skb);
+ if (reason) {
rsk = sk;
goto reset;
}
@@ -1688,6 +1690,7 @@ int tcp_v4_do_rcv(struct sock *sk, struct sk_buff *skb)
reset:
tcp_v4_send_reset(rsk, skb);
discard:
+ SKB_DR_OR(reason, NOT_SPECIFIED);
kfree_skb_reason(skb, reason);
/* Be careful here. If this function gets more complicated and
* gcc suffers from register pressure on the x86, sk (in %ebx)
@@ -2019,12 +2022,15 @@ int tcp_v4_rcv(struct sk_buff *skb)
if (nsk == sk) {
reqsk_put(req);
tcp_v4_restore_cb(skb);
- } else if (tcp_child_process(sk, nsk, skb)) {
- tcp_v4_send_reset(nsk, skb);
- goto discard_and_relse;
} else {
- sock_put(sk);
- return 0;
+ drop_reason = tcp_child_process(sk, nsk, skb);
+ if (drop_reason) {
+ tcp_v4_send_reset(nsk, skb);
+ goto discard_and_relse;
+ } else {
+ sock_put(sk);
+ return 0;
+ }
}
}

diff --git a/net/ipv4/tcp_minisocks.c b/net/ipv4/tcp_minisocks.c
index 6854bb1fb32b..1a21018f6f64 100644
--- a/net/ipv4/tcp_minisocks.c
+++ b/net/ipv4/tcp_minisocks.c
@@ -821,11 +821,12 @@ EXPORT_SYMBOL(tcp_check_req);
* be created.
*/

-int tcp_child_process(struct sock *parent, struct sock *child,
- struct sk_buff *skb)
+enum skb_drop_reason tcp_child_process(struct sock *parent,
+ struct sock *child,
+ struct sk_buff *skb)
__releases(&((child)->sk_lock.slock))
{
- int ret = 0;
+ enum skb_drop_reason reason = SKB_NOT_DROPPED_YET;
int state = child->sk_state;

/* record sk_napi_id and sk_rx_queue_mapping of child. */
@@ -833,7 +834,7 @@ int tcp_child_process(struct sock *parent, struct sock *child,

tcp_segs_in(tcp_sk(child), skb);
if (!sock_owned_by_user(child)) {
- ret = tcp_rcv_state_process(child, skb);
+ reason = tcp_rcv_state_process(child, skb);
/* Wakeup parent, send SIGIO */
if (state == TCP_SYN_RECV && child->sk_state != state)
parent->sk_data_ready(parent);
@@ -847,6 +848,6 @@ int tcp_child_process(struct sock *parent, struct sock *child,

bh_unlock_sock(child);
sock_put(child);
- return ret;
+ return reason;
}
EXPORT_SYMBOL(tcp_child_process);
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 636ed23d9af0..d8236d51dd47 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -1489,7 +1489,8 @@ int tcp_v6_do_rcv(struct sock *sk, struct sk_buff *skb)
goto discard;

if (nsk != sk) {
- if (tcp_child_process(sk, nsk, skb))
+ reason = tcp_child_process(sk, nsk, skb);
+ if (reason)
goto reset;
if (opt_skb)
__kfree_skb(opt_skb);
@@ -1498,7 +1499,8 @@ int tcp_v6_do_rcv(struct sock *sk, struct sk_buff *skb)
} else
sock_rps_save_rxhash(sk, skb);

- if (tcp_rcv_state_process(sk, skb))
+ reason = tcp_rcv_state_process(sk, skb);
+ if (reason)
goto reset;
if (opt_skb)
goto ipv6_pktoptions;
@@ -1685,12 +1687,15 @@ INDIRECT_CALLABLE_SCOPE int tcp_v6_rcv(struct sk_buff *skb)
if (nsk == sk) {
reqsk_put(req);
tcp_v6_restore_cb(skb);
- } else if (tcp_child_process(sk, nsk, skb)) {
- tcp_v6_send_reset(nsk, skb);
- goto discard_and_relse;
} else {
- sock_put(sk);
- return 0;
+ drop_reason = tcp_child_process(sk, nsk, skb);
+ if (drop_reason) {
+ tcp_v6_send_reset(nsk, skb);
+ goto discard_and_relse;
+ } else {
+ sock_put(sk);
+ return 0;
+ }
}
}

--
2.36.1