Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/net/ipv4/udp_offload.c b/net/ipv4/udp_offload.c
index 0c0522b..a3908e5 100644
--- a/net/ipv4/udp_offload.c
+++ b/net/ipv4/udp_offload.c
@@ -1,18 +1,15 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
 /*
  *	IPV4 GSO/GRO offload support
  *	Linux INET implementation
  *
- *	This program is free software; you can redistribute it and/or
- *	modify it under the terms of the GNU General Public License
- *	as published by the Free Software Foundation; either version
- *	2 of the License, or (at your option) any later version.
- *
  *	UDPv4 GSO support
  */
 
 #include <linux/skbuff.h>
 #include <net/udp.h>
 #include <net/protocol.h>
+#include <net/inet_common.h>
 
 static struct sk_buff *__skb_udp_tunnel_segment(struct sk_buff *skb,
 	netdev_features_t features,
@@ -211,7 +208,7 @@
 		gso_skb->destructor = NULL;
 
 	segs = skb_segment(gso_skb, features);
-	if (unlikely(IS_ERR_OR_NULL(segs))) {
+	if (IS_ERR_OR_NULL(segs)) {
 		if (copy_dtor)
 			gso_skb->destructor = sock_wfree;
 		return segs;
@@ -227,6 +224,11 @@
 	seg = segs;
 	uh = udp_hdr(seg);
 
+	/* preserve TX timestamp flags and TS key for first segment */
+	skb_shinfo(seg)->tskey = skb_shinfo(gso_skb)->tskey;
+	skb_shinfo(seg)->tx_flags |=
+			(skb_shinfo(gso_skb)->tx_flags & SKBTX_ANY_TSTAMP);
+
 	/* compute checksum adjustment based on old length versus new */
 	newlen = htons(sizeof(*uh) + mss);
 	check = csum16_add(csum16_sub(uh->check, uh->len), newlen);
@@ -343,6 +345,64 @@
 	return segs;
 }
 
+#define UDP_GRO_CNT_MAX 64
+static struct sk_buff *udp_gro_receive_segment(struct list_head *head,
+					       struct sk_buff *skb)
+{
+	struct udphdr *uh = udp_hdr(skb);
+	struct sk_buff *pp = NULL;
+	struct udphdr *uh2;
+	struct sk_buff *p;
+	unsigned int ulen;
+
+	/* requires non zero csum, for symmetry with GSO */
+	if (!uh->check) {
+		NAPI_GRO_CB(skb)->flush = 1;
+		return NULL;
+	}
+
+	/* Do not deal with padded or malicious packets, sorry ! */
+	ulen = ntohs(uh->len);
+	if (ulen <= sizeof(*uh) || ulen != skb_gro_len(skb)) {
+		NAPI_GRO_CB(skb)->flush = 1;
+		return NULL;
+	}
+	/* pull encapsulating udp header */
+	skb_gro_pull(skb, sizeof(struct udphdr));
+	skb_gro_postpull_rcsum(skb, uh, sizeof(struct udphdr));
+
+	list_for_each_entry(p, head, list) {
+		if (!NAPI_GRO_CB(p)->same_flow)
+			continue;
+
+		uh2 = udp_hdr(p);
+
+		/* Match ports only, as csum is always non zero */
+		if ((*(u32 *)&uh->source != *(u32 *)&uh2->source)) {
+			NAPI_GRO_CB(p)->same_flow = 0;
+			continue;
+		}
+
+		/* Terminate the flow on len mismatch or if it grow "too much".
+		 * Under small packet flood GRO count could elsewhere grow a lot
+		 * leading to excessive truesize values.
+		 * On len mismatch merge the first packet shorter than gso_size,
+		 * otherwise complete the GRO packet.
+		 */
+		if (ulen > ntohs(uh2->len) || skb_gro_receive(p, skb) ||
+		    ulen != ntohs(uh2->len) ||
+		    NAPI_GRO_CB(p)->count >= UDP_GRO_CNT_MAX)
+			pp = p;
+
+		return pp;
+	}
+
+	/* mismatch, but we never need to flush */
+	return NULL;
+}
+
+INDIRECT_CALLABLE_DECLARE(struct sock *udp6_lib_lookup_skb(struct sk_buff *skb,
+						   __be16 sport, __be16 dport));
 struct sk_buff *udp_gro_receive(struct list_head *head, struct sk_buff *skb,
 				struct udphdr *uh, udp_lookup_t lookup)
 {
@@ -353,23 +413,28 @@
 	int flush = 1;
 	struct sock *sk;
 
+	rcu_read_lock();
+	sk = INDIRECT_CALL_INET(lookup, udp6_lib_lookup_skb,
+				udp4_lib_lookup_skb, skb, uh->source, uh->dest);
+	if (!sk)
+		goto out_unlock;
+
+	if (udp_sk(sk)->gro_enabled) {
+		pp = call_gro_receive(udp_gro_receive_segment, head, skb);
+		rcu_read_unlock();
+		return pp;
+	}
+
 	if (NAPI_GRO_CB(skb)->encap_mark ||
 	    (skb->ip_summed != CHECKSUM_PARTIAL &&
 	     NAPI_GRO_CB(skb)->csum_cnt == 0 &&
-	     !NAPI_GRO_CB(skb)->csum_valid))
-		goto out;
+	     !NAPI_GRO_CB(skb)->csum_valid) ||
+	    !udp_sk(sk)->gro_receive)
+		goto out_unlock;
 
 	/* mark that this skb passed once through the tunnel gro layer */
 	NAPI_GRO_CB(skb)->encap_mark = 1;
 
-	rcu_read_lock();
-	sk = (*lookup)(skb, uh->source, uh->dest);
-
-	if (sk && udp_sk(sk)->gro_receive)
-		goto unflush;
-	goto out_unlock;
-
-unflush:
 	flush = 0;
 
 	list_for_each_entry(p, head, list) {
@@ -394,18 +459,17 @@
 
 out_unlock:
 	rcu_read_unlock();
-out:
 	skb_gro_flush_final(skb, pp, flush);
 	return pp;
 }
 EXPORT_SYMBOL(udp_gro_receive);
 
-static struct sk_buff *udp4_gro_receive(struct list_head *head,
-					struct sk_buff *skb)
+INDIRECT_CALLABLE_SCOPE
+struct sk_buff *udp4_gro_receive(struct list_head *head, struct sk_buff *skb)
 {
 	struct udphdr *uh = udp_gro_udphdr(skb);
 
-	if (unlikely(!uh))
+	if (unlikely(!uh) || !static_branch_unlikely(&udp_encap_needed_key))
 		goto flush;
 
 	/* Don't bother verifying checksum if we're going to flush anyway. */
@@ -427,6 +491,19 @@
 	return NULL;
 }
 
+static int udp_gro_complete_segment(struct sk_buff *skb)
+{
+	struct udphdr *uh = udp_hdr(skb);
+
+	skb->csum_start = (unsigned char *)uh - skb->head;
+	skb->csum_offset = offsetof(struct udphdr, check);
+	skb->ip_summed = CHECKSUM_PARTIAL;
+
+	skb_shinfo(skb)->gso_segs = NAPI_GRO_CB(skb)->count;
+	skb_shinfo(skb)->gso_type |= SKB_GSO_UDP_L4;
+	return 0;
+}
+
 int udp_gro_complete(struct sk_buff *skb, int nhoff,
 		     udp_lookup_t lookup)
 {
@@ -437,16 +514,22 @@
 
 	uh->len = newlen;
 
-	/* Set encapsulation before calling into inner gro_complete() functions
-	 * to make them set up the inner offsets.
-	 */
-	skb->encapsulation = 1;
-
 	rcu_read_lock();
-	sk = (*lookup)(skb, uh->source, uh->dest);
-	if (sk && udp_sk(sk)->gro_complete)
+	sk = INDIRECT_CALL_INET(lookup, udp6_lib_lookup_skb,
+				udp4_lib_lookup_skb, skb, uh->source, uh->dest);
+	if (sk && udp_sk(sk)->gro_enabled) {
+		err = udp_gro_complete_segment(skb);
+	} else if (sk && udp_sk(sk)->gro_complete) {
+		skb_shinfo(skb)->gso_type = uh->check ? SKB_GSO_UDP_TUNNEL_CSUM
+					: SKB_GSO_UDP_TUNNEL;
+
+		/* Set encapsulation before calling into inner gro_complete()
+		 * functions to make them set up the inner offsets.
+		 */
+		skb->encapsulation = 1;
 		err = udp_sk(sk)->gro_complete(sk, skb,
 				nhoff + sizeof(struct udphdr));
+	}
 	rcu_read_unlock();
 
 	if (skb->remcsum_offload)
@@ -456,18 +539,14 @@
 }
 EXPORT_SYMBOL(udp_gro_complete);
 
-static int udp4_gro_complete(struct sk_buff *skb, int nhoff)
+INDIRECT_CALLABLE_SCOPE int udp4_gro_complete(struct sk_buff *skb, int nhoff)
 {
 	const struct iphdr *iph = ip_hdr(skb);
 	struct udphdr *uh = (struct udphdr *)(skb->data + nhoff);
 
-	if (uh->check) {
-		skb_shinfo(skb)->gso_type |= SKB_GSO_UDP_TUNNEL_CSUM;
+	if (uh->check)
 		uh->check = ~udp_v4_check(skb->len - nhoff, iph->saddr,
 					  iph->daddr, 0);
-	} else {
-		skb_shinfo(skb)->gso_type |= SKB_GSO_UDP_TUNNEL;
-	}
 
 	return udp_gro_complete(skb, nhoff, udp4_lib_lookup_skb);
 }