[PATCH RESEND net-next v5 0/4] net: icmp: add skb drop reasons to icmp

[PATCH RESEND net-next v5 0/4] net: icmp: add skb drop reasons to icmp

[menglong8.dong]

From: Menglong Dong <imagedong@tencent.com>

In the commit c504e5c2f964 ("net: skb: introduce kfree_skb_reason()"),
we added the support of reporting the reasons of skb drops to kfree_skb
tracepoint. And in this series patches, reasons for skb drops are added
to ICMP protocol.

In order to report the reasons of skb drops in 'sock_queue_rcv_skb()',
the function 'sock_queue_rcv_skb_reason()' is introduced in the 1th
patch, which is used in the 3th patch.

As David Ahern suggested, the reasons for skb drops should be more
general and not be code based. Therefore, in the 2th patch,
SKB_DROP_REASON_PTYPE_ABSENT is renamed to
SKB_DROP_REASON_UNHANDLED_PROTO, which is used for the cases of no
L3 protocol handler, no L4 protocol handler, version extensions, etc.

In the 3th patch, we introduce the new function __ping_queue_rcv_skb()
to report drop reasons by its return value and keep the return value of
ping_queue_rcv_skb() still.

In the 4th patch, we make ICMP message handler functions return drop
reasons, which means we change the return type of 'handler()' in
'struct icmp_control' from 'bool' to 'enum skb_drop_reason'. This
changed its original intention, as 'false' means failure, but
'SKB_NOT_DROPPED_YET', which is 0, means success now. Therefore, we
have to change all usages of these handler. Following "handler"
functions are involved:

icmp_unreach()
icmp_redirect()
icmp_echo()
icmp_timestamp()
icmp_discard()

And following drop reasons are added(what they mean can be see
in the document for them):

SKB_DROP_REASON_ICMP_CSUM
SKB_DROP_REASON_INVALID_PROTO

The reason 'INVALID_PROTO' is introduced for the case that the packet
doesn't follow rfc 1122 and is dropped. I think this reason is different
from the 'UNHANDLED_PROTO', as the 'UNHANDLED_PROTO' means the packet is
fine, and it is just not supported. This is not a common case, and I
believe we can locate the problem from the data in the packet. For now,
this 'INVALID_PROTO' is used for the icmp broadcasts with wrong types.

Maybe there should be a document file for these reasons. For example,
list all the case that causes the 'INVALID_PROTO' drop reason. Therefore,
users can locate their problems according to the document.

Changes since v4:
- rename SKB_DROP_REASON_RFC_1122 to SKB_DROP_REASON_INVALID_PROTO

Changes since v3:
- rename SKB_DROP_REASON_PTYPE_ABSENT to SKB_DROP_REASON_UNHANDLED_PROTO
  in the 2th patch
- fix the return value problem of ping_queue_rcv_skb() in the 3th patch
- remove SKB_DROP_REASON_ICMP_TYPE and SKB_DROP_REASON_ICMP_BROADCAST
  and introduce the SKB_DROP_REASON_RFC_1122 in the 4th patch

Changes since v2:
- fix aliegnment problem in the 2th patch

Changes since v1:
- introduce __ping_queue_rcv_skb() instead of change the return value
  of ping_queue_rcv_skb() in the 2th patch, as Paolo suggested

Menglong Dong (4):
  net: sock: introduce sock_queue_rcv_skb_reason()
  net: skb: rename SKB_DROP_REASON_PTYPE_ABSENT
  net: icmp: introduce __ping_queue_rcv_skb() to report drop reasons
  net: icmp: add skb drop reasons to icmp protocol

 include/linux/skbuff.h     | 13 ++++---
 include/net/ping.h         |  2 +-
 include/net/sock.h         |  9 ++++-
 include/trace/events/skb.h |  4 +-
 net/core/dev.c             |  8 ++--
 net/core/sock.c            | 30 ++++++++++++---
 net/ipv4/icmp.c            | 75 ++++++++++++++++++++++----------------
 net/ipv4/ping.c            | 32 ++++++++++------
 net/ipv6/icmp.c            | 24 +++++++-----
 9 files changed, 127 insertions(+), 70 deletions(-)

-- 
2.35.1

[PATCH RESEND net-next v5 1/4] net: sock: introduce sock_queue_rcv_skb_reason()

[menglong8.dong]

From: Menglong Dong <imagedong@tencent.com>

In order to report the reasons of skb drops in 'sock_queue_rcv_skb()',
introduce the function 'sock_queue_rcv_skb_reason()'.

As the return value of 'sock_queue_rcv_skb()' is used as the error code,
we can't make it as drop reason and have to pass extra output argument.
'sock_queue_rcv_skb()' is used in many places, so we can't change it
directly.

Introduce the new function 'sock_queue_rcv_skb_reason()' and make
'sock_queue_rcv_skb()' an inline call to it.

Reviewed-by: Hao Peng <flyingpeng@tencent.com>
Reviewed-by: Jiang Biao <benbjiang@tencent.com>
Signed-off-by: Menglong Dong <imagedong@tencent.com>
---
 include/net/sock.h |  9 ++++++++-
 net/core/sock.c    | 30 ++++++++++++++++++++++++------
 2 files changed, 32 insertions(+), 7 deletions(-)

diff --git a/include/net/sock.h b/include/net/sock.h
index c4b91fc19b9c..1a988e605f09 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -2392,7 +2392,14 @@ int __sk_queue_drop_skb(struct sock *sk, struct sk_buff_head *sk_queue,
 			void (*destructor)(struct sock *sk,
 					   struct sk_buff *skb));
 int __sock_queue_rcv_skb(struct sock *sk, struct sk_buff *skb);
-int sock_queue_rcv_skb(struct sock *sk, struct sk_buff *skb);
+
+int sock_queue_rcv_skb_reason(struct sock *sk, struct sk_buff *skb,
+			      enum skb_drop_reason *reason);
+
+static inline int sock_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
+{
+	return sock_queue_rcv_skb_reason(sk, skb, NULL);
+}
 
 int sock_queue_err_skb(struct sock *sk, struct sk_buff *skb);
 struct sk_buff *sock_dequeue_err_skb(struct sock *sk);
diff --git a/net/core/sock.c b/net/core/sock.c
index 1180a0cb0110..2cae991f817e 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -503,17 +503,35 @@ int __sock_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
 }
 EXPORT_SYMBOL(__sock_queue_rcv_skb);
 
-int sock_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
+int sock_queue_rcv_skb_reason(struct sock *sk, struct sk_buff *skb,
+			      enum skb_drop_reason *reason)
 {
+	enum skb_drop_reason drop_reason;
 	int err;
 
 	err = sk_filter(sk, skb);
-	if (err)
-		return err;
-
-	return __sock_queue_rcv_skb(sk, skb);
+	if (err) {
+		drop_reason = SKB_DROP_REASON_SOCKET_FILTER;
+		goto out;
+	}
+	err = __sock_queue_rcv_skb(sk, skb);
+	switch (err) {
+	case -ENOMEM:
+		drop_reason = SKB_DROP_REASON_SOCKET_RCVBUFF;
+		break;
+	case -ENOBUFS:
+		drop_reason = SKB_DROP_REASON_PROTO_MEM;
+		break;
+	default:
+		drop_reason = SKB_NOT_DROPPED_YET;
+		break;
+	}
+out:
+	if (reason)
+		*reason = drop_reason;
+	return err;
 }
-EXPORT_SYMBOL(sock_queue_rcv_skb);
+EXPORT_SYMBOL(sock_queue_rcv_skb_reason);
 
 int __sk_receive_skb(struct sock *sk, struct sk_buff *skb,
 		     const int nested, unsigned int trim_cap, bool refcounted)
-- 
2.35.1

[PATCH RESEND net-next v5 2/4] net: skb: rename SKB_DROP_REASON_PTYPE_ABSENT

[menglong8.dong]

From: Menglong Dong <imagedong@tencent.com>

As David Ahern suggested, the reasons for skb drops should be more
general and not be code based.

Therefore, rename SKB_DROP_REASON_PTYPE_ABSENT to
SKB_DROP_REASON_UNHANDLED_PROTO, which is used for the cases of no
L3 protocol handler, no L4 protocol handler, version extensions, etc.

From previous discussion, now we have the aim to make these reasons
more abstract and users based, avoiding code based.

Signed-off-by: Menglong Dong <imagedong@tencent.com>
---
 include/linux/skbuff.h     | 8 +++-----
 include/trace/events/skb.h | 2 +-
 net/core/dev.c             | 8 +++-----
 3 files changed, 7 insertions(+), 11 deletions(-)

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 26538ceb4b01..10ba07892c46 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -408,11 +408,9 @@ enum skb_drop_reason {
 					 */
 	SKB_DROP_REASON_XDP,		/* dropped by XDP in input path */
 	SKB_DROP_REASON_TC_INGRESS,	/* dropped in TC ingress HOOK */
-	SKB_DROP_REASON_PTYPE_ABSENT,	/* not packet_type found to handle
-					 * the skb. For an etner packet,
-					 * this means that L3 protocol is
-					 * not supported
-					 */
+	SKB_DROP_REASON_UNHANDLED_PROTO,	/* protocol not implemented
+						 * or not supported
+						 */
 	SKB_DROP_REASON_SKB_CSUM,	/* sk_buff checksum computation
 					 * error
 					 */
diff --git a/include/trace/events/skb.h b/include/trace/events/skb.h
index e1670e1e4934..85abd7cbd221 100644
--- a/include/trace/events/skb.h
+++ b/include/trace/events/skb.h
@@ -50,7 +50,7 @@
 	EM(SKB_DROP_REASON_CPU_BACKLOG, CPU_BACKLOG)		\
 	EM(SKB_DROP_REASON_XDP, XDP)				\
 	EM(SKB_DROP_REASON_TC_INGRESS, TC_INGRESS)		\
-	EM(SKB_DROP_REASON_PTYPE_ABSENT, PTYPE_ABSENT)		\
+	EM(SKB_DROP_REASON_UNHANDLED_PROTO, UNHANDLED_PROTO)	\
 	EM(SKB_DROP_REASON_SKB_CSUM, SKB_CSUM)			\
 	EM(SKB_DROP_REASON_SKB_GSO_SEG, SKB_GSO_SEG)		\
 	EM(SKB_DROP_REASON_SKB_UCOPY_FAULT, SKB_UCOPY_FAULT)	\
diff --git a/net/core/dev.c b/net/core/dev.c
index 75bab5b0dbae..d73b35e6aae4 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -5359,13 +5359,11 @@ static int __netif_receive_skb_core(struct sk_buff **pskb, bool pfmemalloc,
 		*ppt_prev = pt_prev;
 	} else {
 drop:
-		if (!deliver_exact) {
+		if (!deliver_exact)
 			dev_core_stats_rx_dropped_inc(skb->dev);
-			kfree_skb_reason(skb, SKB_DROP_REASON_PTYPE_ABSENT);
-		} else {
+		else
 			dev_core_stats_rx_nohandler_inc(skb->dev);
-			kfree_skb(skb);
-		}
+		kfree_skb_reason(skb, SKB_DROP_REASON_UNHANDLED_PROTO);
 		/* Jamal, now you will not able to escape explaining
 		 * me how you were going to use this. :-)
 		 */
-- 
2.35.1

[PATCH RESEND net-next v5 3/4] net: icmp: introduce __ping_queue_rcv_skb() to report drop reasons

[menglong8.dong]

From: Menglong Dong <imagedong@tencent.com>

In order to avoid to change the return value of ping_queue_rcv_skb(),
introduce the function __ping_queue_rcv_skb(), which is able to report
the reasons of skb drop as its return value, as Paolo suggested.

Meanwhile, make ping_queue_rcv_skb() a simple call to
__ping_queue_rcv_skb().

The kfree_skb() and sock_queue_rcv_skb() used in ping_queue_rcv_skb()
are replaced with kfree_skb_reason() and sock_queue_rcv_skb_reason()
now.

Reviewed-by: Hao Peng <flyingpeng@tencent.com>
Reviewed-by: Jiang Biao <benbjiang@tencent.com>
Signed-off-by: Menglong Dong <imagedong@tencent.com>
---
v4:
- fix the return value problem of ping_queue_rcv_skb()

v3:
- fix aligenment problem

v2:
- introduce __ping_queue_rcv_skb() instead of change the return value
  of ping_queue_rcv_skb()
---
 net/ipv4/ping.c | 18 +++++++++++++-----
 1 file changed, 13 insertions(+), 5 deletions(-)

diff --git a/net/ipv4/ping.c b/net/ipv4/ping.c
index 3ee947557b88..877270ad17c9 100644
--- a/net/ipv4/ping.c
+++ b/net/ipv4/ping.c
@@ -934,16 +934,24 @@ int ping_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, int noblock,
 }
 EXPORT_SYMBOL_GPL(ping_recvmsg);
 
-int ping_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
+static enum skb_drop_reason __ping_queue_rcv_skb(struct sock *sk,
+						 struct sk_buff *skb)
 {
+	enum skb_drop_reason reason;
+
 	pr_debug("ping_queue_rcv_skb(sk=%p,sk->num=%d,skb=%p)\n",
 		 inet_sk(sk), inet_sk(sk)->inet_num, skb);
-	if (sock_queue_rcv_skb(sk, skb) < 0) {
-		kfree_skb(skb);
+	if (sock_queue_rcv_skb_reason(sk, skb, &reason) < 0) {
+		kfree_skb_reason(skb, reason);
 		pr_debug("ping_queue_rcv_skb -> failed\n");
-		return -1;
+		return reason;
 	}
-	return 0;
+	return SKB_NOT_DROPPED_YET;
+}
+
+int ping_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
+{
+	return __ping_queue_rcv_skb(sk, skb) ? -1 : 0;
 }
 EXPORT_SYMBOL_GPL(ping_queue_rcv_skb);
 
-- 
2.35.1

[PATCH RESEND net-next v5 4/4] net: icmp: add skb drop reasons to icmp protocol

[menglong8.dong]

From: Menglong Dong <imagedong@tencent.com>

Replace kfree_skb() used in icmp_rcv() and icmpv6_rcv() with
kfree_skb_reason().

In order to get the reasons of the skb drops after icmp message handle,
we change the return type of 'handler()' in 'struct icmp_control' from
'bool' to 'enum skb_drop_reason'. This may change its original
intention, as 'false' means failure, but 'SKB_NOT_DROPPED_YET' means
success now. Therefore, all 'handler' and the call of them need to be
handled. Following 'handler' functions are involved:

icmp_unreach()
icmp_redirect()
icmp_echo()
icmp_timestamp()
icmp_discard()

And following new drop reasons are added:

SKB_DROP_REASON_ICMP_CSUM
SKB_DROP_REASON_INVALID_PROTO

The reason 'INVALID_PROTO' is introduced for the case that the packet
doesn't follow rfc 1122 and is dropped. This is not a common case, and
I believe we can locate the problem from the data in the packet. For now,
this 'INVALID_PROTO' is used for the icmp broadcasts with wrong types.

Maybe there should be a document file for these reasons. For example,
list all the case that causes the 'UNHANDLED_PROTO' and 'INVALID_PROTO'
drop reason. Therefore, users can locate their problems according to the
document.

Reviewed-by: Hao Peng <flyingpeng@tencent.com>
Reviewed-by: Jiang Biao <benbjiang@tencent.com>
Signed-off-by: Menglong Dong <imagedong@tencent.com>
---
v5:
- rename SKB_DROP_REASON_RFC_1122 to SKB_DROP_REASON_INVALID_PROTO

v4:
- remove SKB_DROP_REASON_ICMP_TYPE and SKB_DROP_REASON_ICMP_BROADCAST
  and introduce the SKB_DROP_REASON_RFC_1122
---
 include/linux/skbuff.h     |  5 +++
 include/net/ping.h         |  2 +-
 include/trace/events/skb.h |  2 +
 net/ipv4/icmp.c            | 75 ++++++++++++++++++++++----------------
 net/ipv4/ping.c            | 14 ++++---
 net/ipv6/icmp.c            | 24 +++++++-----
 6 files changed, 75 insertions(+), 47 deletions(-)

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 10ba07892c46..92e8c8d7410e 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -442,6 +442,11 @@ enum skb_drop_reason {
 	SKB_DROP_REASON_TAP_TXFILTER,	/* dropped by tx filter implemented
 					 * at tun/tap, e.g., check_filter()
 					 */
+	SKB_DROP_REASON_ICMP_CSUM,	/* ICMP checksum error */
+	SKB_DROP_REASON_INVALID_PROTO,	/* the packet doesn't follow RFC
+					 * 2211, such as a broadcasts
+					 * ICMP_TIMESTAMP
+					 */
 	SKB_DROP_REASON_MAX,
 };
 
diff --git a/include/net/ping.h b/include/net/ping.h
index 2fe78874318c..b68fbfdb606f 100644
--- a/include/net/ping.h
+++ b/include/net/ping.h
@@ -76,7 +76,7 @@ int  ping_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, int noblock,
 int  ping_common_sendmsg(int family, struct msghdr *msg, size_t len,
 			 void *user_icmph, size_t icmph_len);
 int  ping_queue_rcv_skb(struct sock *sk, struct sk_buff *skb);
-bool ping_rcv(struct sk_buff *skb);
+enum skb_drop_reason ping_rcv(struct sk_buff *skb);
 
 #ifdef CONFIG_PROC_FS
 void *ping_seq_start(struct seq_file *seq, loff_t *pos, sa_family_t family);
diff --git a/include/trace/events/skb.h b/include/trace/events/skb.h
index 85abd7cbd221..42647114fffe 100644
--- a/include/trace/events/skb.h
+++ b/include/trace/events/skb.h
@@ -61,6 +61,8 @@
 	EM(SKB_DROP_REASON_HDR_TRUNC, HDR_TRUNC)		\
 	EM(SKB_DROP_REASON_TAP_FILTER, TAP_FILTER)		\
 	EM(SKB_DROP_REASON_TAP_TXFILTER, TAP_TXFILTER)		\
+	EM(SKB_DROP_REASON_ICMP_CSUM, ICMP_CSUM)		\
+	EM(SKB_DROP_REASON_INVALID_PROTO, INVALID_PROTO)	\
 	EMe(SKB_DROP_REASON_MAX, MAX)
 
 #undef EM
diff --git a/net/ipv4/icmp.c b/net/ipv4/icmp.c
index 72a375c7f417..236debd9fded 100644
--- a/net/ipv4/icmp.c
+++ b/net/ipv4/icmp.c
@@ -186,7 +186,7 @@ EXPORT_SYMBOL(icmp_err_convert);
  */
 
 struct icmp_control {
-	bool (*handler)(struct sk_buff *skb);
+	enum skb_drop_reason (*handler)(struct sk_buff *skb);
 	short   error;		/* This ICMP is classed as an error message */
 };
 
@@ -839,8 +839,9 @@ static bool icmp_tag_validation(int proto)
  *	ICMP_PARAMETERPROB.
  */
 
-static bool icmp_unreach(struct sk_buff *skb)
+static enum skb_drop_reason icmp_unreach(struct sk_buff *skb)
 {
+	enum skb_drop_reason reason = SKB_NOT_DROPPED_YET;
 	const struct iphdr *iph;
 	struct icmphdr *icmph;
 	struct net *net;
@@ -860,8 +861,10 @@ static bool icmp_unreach(struct sk_buff *skb)
 	icmph = icmp_hdr(skb);
 	iph   = (const struct iphdr *)skb->data;
 
-	if (iph->ihl < 5) /* Mangled header, drop. */
+	if (iph->ihl < 5)  { /* Mangled header, drop. */
+		reason = SKB_DROP_REASON_IP_INHDR;
 		goto out_err;
+	}
 
 	switch (icmph->type) {
 	case ICMP_DEST_UNREACH:
@@ -941,10 +944,10 @@ static bool icmp_unreach(struct sk_buff *skb)
 	icmp_socket_deliver(skb, info);
 
 out:
-	return true;
+	return reason;
 out_err:
 	__ICMP_INC_STATS(net, ICMP_MIB_INERRORS);
-	return false;
+	return reason ?: SKB_DROP_REASON_NOT_SPECIFIED;
 }
 
 
@@ -952,20 +955,20 @@ static bool icmp_unreach(struct sk_buff *skb)
  *	Handle ICMP_REDIRECT.
  */
 
-static bool icmp_redirect(struct sk_buff *skb)
+static enum skb_drop_reason icmp_redirect(struct sk_buff *skb)
 {
 	if (skb->len < sizeof(struct iphdr)) {
 		__ICMP_INC_STATS(dev_net(skb->dev), ICMP_MIB_INERRORS);
-		return false;
+		return SKB_DROP_REASON_PKT_TOO_SMALL;
 	}
 
 	if (!pskb_may_pull(skb, sizeof(struct iphdr))) {
 		/* there aught to be a stat */
-		return false;
+		return SKB_DROP_REASON_NOMEM;
 	}
 
 	icmp_socket_deliver(skb, ntohl(icmp_hdr(skb)->un.gateway));
-	return true;
+	return SKB_NOT_DROPPED_YET;
 }
 
 /*
@@ -982,7 +985,7 @@ static bool icmp_redirect(struct sk_buff *skb)
  *	See also WRT handling of options once they are done and working.
  */
 
-static bool icmp_echo(struct sk_buff *skb)
+static enum skb_drop_reason icmp_echo(struct sk_buff *skb)
 {
 	struct icmp_bxm icmp_param;
 	struct net *net;
@@ -990,7 +993,7 @@ static bool icmp_echo(struct sk_buff *skb)
 	net = dev_net(skb_dst(skb)->dev);
 	/* should there be an ICMP stat for ignored echos? */
 	if (net->ipv4.sysctl_icmp_echo_ignore_all)
-		return true;
+		return SKB_NOT_DROPPED_YET;
 
 	icmp_param.data.icmph	   = *icmp_hdr(skb);
 	icmp_param.skb		   = skb;
@@ -1001,10 +1004,10 @@ static bool icmp_echo(struct sk_buff *skb)
 	if (icmp_param.data.icmph.type == ICMP_ECHO)
 		icmp_param.data.icmph.type = ICMP_ECHOREPLY;
 	else if (!icmp_build_probe(skb, &icmp_param.data.icmph))
-		return true;
+		return SKB_NOT_DROPPED_YET;
 
 	icmp_reply(&icmp_param, skb);
-	return true;
+	return SKB_NOT_DROPPED_YET;
 }
 
 /*	Helper for icmp_echo and icmpv6_echo_reply.
@@ -1122,7 +1125,7 @@ EXPORT_SYMBOL_GPL(icmp_build_probe);
  *		  MUST be accurate to a few minutes.
  *		  MUST be updated at least at 15Hz.
  */
-static bool icmp_timestamp(struct sk_buff *skb)
+static enum skb_drop_reason icmp_timestamp(struct sk_buff *skb)
 {
 	struct icmp_bxm icmp_param;
 	/*
@@ -1147,17 +1150,17 @@ static bool icmp_timestamp(struct sk_buff *skb)
 	icmp_param.data_len	   = 0;
 	icmp_param.head_len	   = sizeof(struct icmphdr) + 12;
 	icmp_reply(&icmp_param, skb);
-	return true;
+	return SKB_NOT_DROPPED_YET;
 
 out_err:
 	__ICMP_INC_STATS(dev_net(skb_dst(skb)->dev), ICMP_MIB_INERRORS);
-	return false;
+	return SKB_DROP_REASON_PKT_TOO_SMALL;
 }
 
-static bool icmp_discard(struct sk_buff *skb)
+static enum skb_drop_reason icmp_discard(struct sk_buff *skb)
 {
 	/* pretend it was a success */
-	return true;
+	return SKB_NOT_DROPPED_YET;
 }
 
 /*
@@ -1165,18 +1168,20 @@ static bool icmp_discard(struct sk_buff *skb)
  */
 int icmp_rcv(struct sk_buff *skb)
 {
-	struct icmphdr *icmph;
+	enum skb_drop_reason reason = SKB_DROP_REASON_NOT_SPECIFIED;
 	struct rtable *rt = skb_rtable(skb);
 	struct net *net = dev_net(rt->dst.dev);
-	bool success;
+	struct icmphdr *icmph;
 
 	if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
 		struct sec_path *sp = skb_sec_path(skb);
 		int nh;
 
 		if (!(sp && sp->xvec[sp->len - 1]->props.flags &
-				 XFRM_STATE_ICMP))
+				 XFRM_STATE_ICMP)) {
+			reason = SKB_DROP_REASON_XFRM_POLICY;
 			goto drop;
+		}
 
 		if (!pskb_may_pull(skb, sizeof(*icmph) + sizeof(struct iphdr)))
 			goto drop;
@@ -1184,8 +1189,11 @@ int icmp_rcv(struct sk_buff *skb)
 		nh = skb_network_offset(skb);
 		skb_set_network_header(skb, sizeof(*icmph));
 
-		if (!xfrm4_policy_check_reverse(NULL, XFRM_POLICY_IN, skb))
+		if (!xfrm4_policy_check_reverse(NULL, XFRM_POLICY_IN,
+						skb)) {
+			reason = SKB_DROP_REASON_XFRM_POLICY;
 			goto drop;
+		}
 
 		skb_set_network_header(skb, nh);
 	}
@@ -1207,13 +1215,13 @@ int icmp_rcv(struct sk_buff *skb)
 		/* We can't use icmp_pointers[].handler() because it is an array of
 		 * size NR_ICMP_TYPES + 1 (19 elements) and PROBE has code 42.
 		 */
-		success = icmp_echo(skb);
-		goto success_check;
+		reason = icmp_echo(skb);
+		goto reason_check;
 	}
 
 	if (icmph->type == ICMP_EXT_ECHOREPLY) {
-		success = ping_rcv(skb);
-		goto success_check;
+		reason = ping_rcv(skb);
+		goto reason_check;
 	}
 
 	/*
@@ -1222,8 +1230,10 @@ int icmp_rcv(struct sk_buff *skb)
 	 *	RFC 1122: 3.2.2  Unknown ICMP messages types MUST be silently
 	 *		  discarded.
 	 */
-	if (icmph->type > NR_ICMP_TYPES)
+	if (icmph->type > NR_ICMP_TYPES) {
+		reason = SKB_DROP_REASON_UNHANDLED_PROTO;
 		goto error;
+	}
 
 	/*
 	 *	Parse the ICMP message
@@ -1239,27 +1249,30 @@ int icmp_rcv(struct sk_buff *skb)
 		if ((icmph->type == ICMP_ECHO ||
 		     icmph->type == ICMP_TIMESTAMP) &&
 		    net->ipv4.sysctl_icmp_echo_ignore_broadcasts) {
+			reason = SKB_DROP_REASON_INVALID_PROTO;
 			goto error;
 		}
 		if (icmph->type != ICMP_ECHO &&
 		    icmph->type != ICMP_TIMESTAMP &&
 		    icmph->type != ICMP_ADDRESS &&
 		    icmph->type != ICMP_ADDRESSREPLY) {
+			reason = SKB_DROP_REASON_INVALID_PROTO;
 			goto error;
 		}
 	}
 
-	success = icmp_pointers[icmph->type].handler(skb);
-success_check:
-	if (success)  {
+	reason = icmp_pointers[icmph->type].handler(skb);
+reason_check:
+	if (!reason)  {
 		consume_skb(skb);
 		return NET_RX_SUCCESS;
 	}
 
 drop:
-	kfree_skb(skb);
+	kfree_skb_reason(skb, reason);
 	return NET_RX_DROP;
 csum_error:
+	reason = SKB_DROP_REASON_ICMP_CSUM;
 	__ICMP_INC_STATS(net, ICMP_MIB_CSUMERRORS);
 error:
 	__ICMP_INC_STATS(net, ICMP_MIB_INERRORS);
diff --git a/net/ipv4/ping.c b/net/ipv4/ping.c
index 877270ad17c9..b383e0393206 100644
--- a/net/ipv4/ping.c
+++ b/net/ipv4/ping.c
@@ -960,12 +960,12 @@ EXPORT_SYMBOL_GPL(ping_queue_rcv_skb);
  *	All we need to do is get the socket.
  */
 
-bool ping_rcv(struct sk_buff *skb)
+enum skb_drop_reason ping_rcv(struct sk_buff *skb)
 {
+	enum skb_drop_reason reason = SKB_DROP_REASON_NO_SOCKET;
 	struct sock *sk;
 	struct net *net = dev_net(skb->dev);
 	struct icmphdr *icmph = icmp_hdr(skb);
-	bool rc = false;
 
 	/* We assume the packet has already been checked by icmp_rcv */
 
@@ -980,15 +980,17 @@ bool ping_rcv(struct sk_buff *skb)
 		struct sk_buff *skb2 = skb_clone(skb, GFP_ATOMIC);
 
 		pr_debug("rcv on socket %p\n", sk);
-		if (skb2 && !ping_queue_rcv_skb(sk, skb2))
-			rc = true;
+		if (skb2)
+			reason = __ping_queue_rcv_skb(sk, skb2);
+		else
+			reason = SKB_DROP_REASON_NOMEM;
 		sock_put(sk);
 	}
 
-	if (!rc)
+	if (reason)
 		pr_debug("no socket, dropping\n");
 
-	return rc;
+	return reason;
 }
 EXPORT_SYMBOL_GPL(ping_rcv);
 
diff --git a/net/ipv6/icmp.c b/net/ipv6/icmp.c
index e6b978ea0e87..01c8003c9fc9 100644
--- a/net/ipv6/icmp.c
+++ b/net/ipv6/icmp.c
@@ -864,21 +864,23 @@ void icmpv6_notify(struct sk_buff *skb, u8 type, u8 code, __be32 info)
 
 static int icmpv6_rcv(struct sk_buff *skb)
 {
+	enum skb_drop_reason reason = SKB_DROP_REASON_NOT_SPECIFIED;
 	struct net *net = dev_net(skb->dev);
 	struct net_device *dev = icmp6_dev(skb);
 	struct inet6_dev *idev = __in6_dev_get(dev);
 	const struct in6_addr *saddr, *daddr;
 	struct icmp6hdr *hdr;
 	u8 type;
-	bool success = false;
 
 	if (!xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb)) {
 		struct sec_path *sp = skb_sec_path(skb);
 		int nh;
 
 		if (!(sp && sp->xvec[sp->len - 1]->props.flags &
-				 XFRM_STATE_ICMP))
+				 XFRM_STATE_ICMP)) {
+			reason = SKB_DROP_REASON_XFRM_POLICY;
 			goto drop_no_count;
+		}
 
 		if (!pskb_may_pull(skb, sizeof(*hdr) + sizeof(struct ipv6hdr)))
 			goto drop_no_count;
@@ -886,8 +888,11 @@ static int icmpv6_rcv(struct sk_buff *skb)
 		nh = skb_network_offset(skb);
 		skb_set_network_header(skb, sizeof(*hdr));
 
-		if (!xfrm6_policy_check_reverse(NULL, XFRM_POLICY_IN, skb))
+		if (!xfrm6_policy_check_reverse(NULL, XFRM_POLICY_IN,
+						skb)) {
+			reason = SKB_DROP_REASON_XFRM_POLICY;
 			goto drop_no_count;
+		}
 
 		skb_set_network_header(skb, nh);
 	}
@@ -924,11 +929,11 @@ static int icmpv6_rcv(struct sk_buff *skb)
 		break;
 
 	case ICMPV6_ECHO_REPLY:
-		success = ping_rcv(skb);
+		reason = ping_rcv(skb);
 		break;
 
 	case ICMPV6_EXT_ECHO_REPLY:
-		success = ping_rcv(skb);
+		reason = ping_rcv(skb);
 		break;
 
 	case ICMPV6_PKT_TOOBIG:
@@ -994,19 +999,20 @@ static int icmpv6_rcv(struct sk_buff *skb)
 	/* until the v6 path can be better sorted assume failure and
 	 * preserve the status quo behaviour for the rest of the paths to here
 	 */
-	if (success)
-		consume_skb(skb);
+	if (reason)
+		kfree_skb_reason(skb, reason);
 	else
-		kfree_skb(skb);
+		consume_skb(skb);
 
 	return 0;
 
 csum_error:
+	reason = SKB_DROP_REASON_ICMP_CSUM;
 	__ICMP6_INC_STATS(dev_net(dev), idev, ICMP6_MIB_CSUMERRORS);
 discard_it:
 	__ICMP6_INC_STATS(dev_net(dev), idev, ICMP6_MIB_INERRORS);
 drop_no_count:
-	kfree_skb(skb);
+	kfree_skb_reason(skb, reason);
 	return 0;
 }
 
-- 
2.35.1

Re: [PATCH RESEND net-next v5 1/4] net: sock: introduce sock_queue_rcv_skb_reason()

[David Ahern]

On 4/7/22 12:20 AM, menglong8.dong@gmail.com wrote:
> From: Menglong Dong <imagedong@tencent.com>
> 
> In order to report the reasons of skb drops in 'sock_queue_rcv_skb()',
> introduce the function 'sock_queue_rcv_skb_reason()'.
> 
> As the return value of 'sock_queue_rcv_skb()' is used as the error code,
> we can't make it as drop reason and have to pass extra output argument.
> 'sock_queue_rcv_skb()' is used in many places, so we can't change it
> directly.
> 
> Introduce the new function 'sock_queue_rcv_skb_reason()' and make
> 'sock_queue_rcv_skb()' an inline call to it.
> 
> Reviewed-by: Hao Peng <flyingpeng@tencent.com>
> Reviewed-by: Jiang Biao <benbjiang@tencent.com>
> Signed-off-by: Menglong Dong <imagedong@tencent.com>
> ---
>  include/net/sock.h |  9 ++++++++-
>  net/core/sock.c    | 30 ++++++++++++++++++++++++------
>  2 files changed, 32 insertions(+), 7 deletions(-)
> 

Reviewed-by: David Ahern <dsahern@kernel.org>

Re: [PATCH RESEND net-next v5 2/4] net: skb: rename SKB_DROP_REASON_PTYPE_ABSENT

[David Ahern]

On 4/7/22 12:20 AM, menglong8.dong@gmail.com wrote:
> From: Menglong Dong <imagedong@tencent.com>
> 
> As David Ahern suggested, the reasons for skb drops should be more
> general and not be code based.
> 
> Therefore, rename SKB_DROP_REASON_PTYPE_ABSENT to
> SKB_DROP_REASON_UNHANDLED_PROTO, which is used for the cases of no
> L3 protocol handler, no L4 protocol handler, version extensions, etc.
> 
> From previous discussion, now we have the aim to make these reasons
> more abstract and users based, avoiding code based.
> 
> Signed-off-by: Menglong Dong <imagedong@tencent.com>
> ---
>  include/linux/skbuff.h     | 8 +++-----
>  include/trace/events/skb.h | 2 +-
>  net/core/dev.c             | 8 +++-----
>  3 files changed, 7 insertions(+), 11 deletions(-)
> 


Reviewed-by: David Ahern <dsahern@kernel.org>

Re: [PATCH RESEND net-next v5 3/4] net: icmp: introduce __ping_queue_rcv_skb() to report drop reasons

[David Ahern]

On 4/7/22 12:20 AM, menglong8.dong@gmail.com wrote:
> From: Menglong Dong <imagedong@tencent.com>
> 
> In order to avoid to change the return value of ping_queue_rcv_skb(),
> introduce the function __ping_queue_rcv_skb(), which is able to report
> the reasons of skb drop as its return value, as Paolo suggested.
> 
> Meanwhile, make ping_queue_rcv_skb() a simple call to
> __ping_queue_rcv_skb().
> 
> The kfree_skb() and sock_queue_rcv_skb() used in ping_queue_rcv_skb()
> are replaced with kfree_skb_reason() and sock_queue_rcv_skb_reason()
> now.
> 
> Reviewed-by: Hao Peng <flyingpeng@tencent.com>
> Reviewed-by: Jiang Biao <benbjiang@tencent.com>
> Signed-off-by: Menglong Dong <imagedong@tencent.com>
> ---
> v4:
> - fix the return value problem of ping_queue_rcv_skb()
> 
> v3:
> - fix aligenment problem
> 
> v2:
> - introduce __ping_queue_rcv_skb() instead of change the return value
>   of ping_queue_rcv_skb()
> ---
>  net/ipv4/ping.c | 18 +++++++++++++-----
>  1 file changed, 13 insertions(+), 5 deletions(-)
> 


Reviewed-by: David Ahern <dsahern@kernel.org>

Re: [PATCH RESEND net-next v5 4/4] net: icmp: add skb drop reasons to icmp protocol

[David Ahern]

On 4/7/22 12:20 AM, menglong8.dong@gmail.com wrote:
> From: Menglong Dong <imagedong@tencent.com>
> 
> Replace kfree_skb() used in icmp_rcv() and icmpv6_rcv() with
> kfree_skb_reason().
> 
> In order to get the reasons of the skb drops after icmp message handle,
> we change the return type of 'handler()' in 'struct icmp_control' from
> 'bool' to 'enum skb_drop_reason'. This may change its original
> intention, as 'false' means failure, but 'SKB_NOT_DROPPED_YET' means
> success now. Therefore, all 'handler' and the call of them need to be
> handled. Following 'handler' functions are involved:
> 
> icmp_unreach()
> icmp_redirect()
> icmp_echo()
> icmp_timestamp()
> icmp_discard()
> 
> And following new drop reasons are added:
> 
> SKB_DROP_REASON_ICMP_CSUM
> SKB_DROP_REASON_INVALID_PROTO
> 
> The reason 'INVALID_PROTO' is introduced for the case that the packet
> doesn't follow rfc 1122 and is dropped. This is not a common case, and
> I believe we can locate the problem from the data in the packet. For now,
> this 'INVALID_PROTO' is used for the icmp broadcasts with wrong types.
> 
> Maybe there should be a document file for these reasons. For example,
> list all the case that causes the 'UNHANDLED_PROTO' and 'INVALID_PROTO'
> drop reason. Therefore, users can locate their problems according to the
> document.
> 
> Reviewed-by: Hao Peng <flyingpeng@tencent.com>
> Reviewed-by: Jiang Biao <benbjiang@tencent.com>
> Signed-off-by: Menglong Dong <imagedong@tencent.com>
> ---
> v5:
> - rename SKB_DROP_REASON_RFC_1122 to SKB_DROP_REASON_INVALID_PROTO
> 
> v4:
> - remove SKB_DROP_REASON_ICMP_TYPE and SKB_DROP_REASON_ICMP_BROADCAST
>   and introduce the SKB_DROP_REASON_RFC_1122
> ---
>  include/linux/skbuff.h     |  5 +++
>  include/net/ping.h         |  2 +-
>  include/trace/events/skb.h |  2 +
>  net/ipv4/icmp.c            | 75 ++++++++++++++++++++++----------------
>  net/ipv4/ping.c            | 14 ++++---
>  net/ipv6/icmp.c            | 24 +++++++-----
>  6 files changed, 75 insertions(+), 47 deletions(-)
> 

Reviewed-by: David Ahern <dsahern@kernel.org>

Re: [PATCH RESEND net-next v5 0/4] net: icmp: add skb drop reasons to icmp

[patchwork-bot+netdevbpf]

Hello:

This series was applied to netdev/net-next.git (master)
by David S. Miller <davem@davemloft.net>:

On Thu,  7 Apr 2022 14:20:48 +0800 you wrote:
> From: Menglong Dong <imagedong@tencent.com>
> 
> In the commit c504e5c2f964 ("net: skb: introduce kfree_skb_reason()"),
> we added the support of reporting the reasons of skb drops to kfree_skb
> tracepoint. And in this series patches, reasons for skb drops are added
> to ICMP protocol.
> 
> [...]

Here is the summary with links:
  - [RESEND,net-next,v5,1/4] net: sock: introduce sock_queue_rcv_skb_reason()
    https://git.kernel.org/netdev/net-next/c/c1b8a56755ee
  - [RESEND,net-next,v5,2/4] net: skb: rename SKB_DROP_REASON_PTYPE_ABSENT
    https://git.kernel.org/netdev/net-next/c/9f8ed577c288
  - [RESEND,net-next,v5,3/4] net: icmp: introduce __ping_queue_rcv_skb() to report drop reasons
    https://git.kernel.org/netdev/net-next/c/41a95a00ebef
  - [RESEND,net-next,v5,4/4] net: icmp: add skb drop reasons to icmp protocol
    https://git.kernel.org/netdev/net-next/c/b384c95a861e

You are awesome, thank you!
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