netfilter: nfnetlink_log: always add a timestamp

Compared to all the other work we're already doing to deliver
an skb to userspace this is very cheap - at worse an extra
call to ktime_get_real() - and very useful.

(and indeed it may even be cheaper if we're running from other hooks)

(background: Android occasionally logs packets which
caused wake from sleep/suspend and we'd like to have
timestamps reliably associated with these events)

Cc: Pablo Neira Ayuso <pablo@netfilter.org>
Cc: Martin KaFai Lau <kafai@fb.com>
Cc: Florian Westphal <fw@strlen.de>
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Signed-off-by: Florian Westphal <fw@strlen.de>

diff --git a/net/netfilter/nfnetlink_log.c b/net/netfilter/nfnetlink_log.c
index e57eb16..53c9e76 100644 (file)
--- a/net/netfilter/nfnetlink_log.c
+++ b/net/netfilter/nfnetlink_log.c
@@ -470,7 +470,6 @@ __build_packet_message(struct nfnl_log_net *log,
        sk_buff_data_t old_tail = inst->skb->tail;
        struct sock *sk;
        const unsigned char *hwhdrp;
-       ktime_t tstamp;
 
        nlh = nfnl_msg_put(inst->skb, 0, 0,
                           nfnl_msg_type(NFNL_SUBSYS_ULOG, NFULNL_MSG_PACKET),
@@ -599,10 +598,9 @@ __build_packet_message(struct nfnl_log_net *log,
                        goto nla_put_failure;
        }
 
-       tstamp = skb_tstamp_cond(skb, false);
-       if (hooknum <= NF_INET_FORWARD && tstamp) {
+       if (hooknum <= NF_INET_FORWARD) {
+               struct timespec64 kts = ktime_to_timespec64(skb_tstamp_cond(skb, true));
                struct nfulnl_msg_packet_timestamp ts;
-               struct timespec64 kts = ktime_to_timespec64(tstamp);
                ts.sec = cpu_to_be64(kts.tv_sec);
                ts.usec = cpu_to_be64(kts.tv_nsec / NSEC_PER_USEC);