1 files changed, 23 insertions, 10 deletions

diff --git a/net/ipv4/ip_sockglue.c b/net/ipv4/ip_sockglue.c
index 31d8c71986b4..5cd99271d3a6 100644
--- a/net/ipv4/ip_sockglue.c
+++ b/net/ipv4/ip_sockglue.c
@@ -432,17 +432,32 @@ void ip_local_error(struct sock *sk, int err, __be32 daddr, __be16 port, u32 inf
                 kfree_skb(skb);
 }
 
-static bool ipv4_pktinfo_prepare_errqueue(const struct sock *sk,
-                                          const struct sk_buff *skb,
-                                          int ee_origin)
+/* IPv4 supports cmsg on all imcp errors and some timestamps
+ *
+ * Timestamp code paths do not initialize the fields expected by cmsg:
+ * the PKTINFO fields in skb->cb[]. Fill those in here.
+ */
+static bool ipv4_datagram_support_cmsg(const struct sock *sk,
+                                       struct sk_buff *skb,
+                                       int ee_origin)
 {
-        struct in_pktinfo *info = PKTINFO_SKB_CB(skb);
+        struct in_pktinfo *info;
+
+        if (ee_origin == SO_EE_ORIGIN_ICMP)
+                return true;
 
-        if ((ee_origin != SO_EE_ORIGIN_TIMESTAMPING) ||
-            (!(sk->sk_tsflags & SOF_TIMESTAMPING_OPT_CMSG)) ||
+        if (ee_origin == SO_EE_ORIGIN_LOCAL)
+                return false;
+
+        /* Support IP_PKTINFO on tstamp packets if requested, to correlate
+         * timestamp with egress dev. Not possible for packets without dev
+         * or without payload (SOF_TIMESTAMPING_OPT_TSONLY).
+         */
+        if ((!(sk->sk_tsflags & SOF_TIMESTAMPING_OPT_CMSG)) ||
             (!skb->dev))
                 return false;
 
+        info = PKTINFO_SKB_CB(skb);
         info->ipi_spec_dst.s_addr = ip_hdr(skb)->saddr;
         info->ipi_ifindex = skb->dev->ifindex;
         return true;
@@ -483,7 +498,7 @@ int ip_recv_error(struct sock *sk, struct msghdr *msg, int len, int *addr_len)
 
         serr = SKB_EXT_ERR(skb);
 
-        if (sin && skb->len) {
+        if (sin && serr->port) {
                 sin->sin_family = AF_INET;
                 sin->sin_addr.s_addr = *(__be32 *)(skb_network_header(skb) +
                                                    serr->addr_offset);
@@ -496,9 +511,7 @@ int ip_recv_error(struct sock *sk, struct msghdr *msg, int len, int *addr_len)
         sin = &errhdr.offender;
         memset(sin, 0, sizeof(*sin));
 
-        if (skb->len &&
-            (serr->ee.ee_origin == SO_EE_ORIGIN_ICMP ||
-             ipv4_pktinfo_prepare_errqueue(sk, skb, serr->ee.ee_origin))) {
+        if (ipv4_datagram_support_cmsg(sk, skb, serr->ee.ee_origin)) {
                 sin->sin_family = AF_INET;
                 sin->sin_addr.s_addr = ip_hdr(skb)->saddr;
                 if (inet_sk(sk)->cmsg_flags)