diff options
author | Florian Westphal <fw@strlen.de> | 2019-04-17 03:17:23 +0300 |
---|---|---|
committer | Pablo Neira Ayuso <pablo@netfilter.org> | 2019-04-22 11:34:30 +0300 |
commit | 916f6efae62305796e012e7c3a7884a267cbacbf (patch) | |
tree | 59c30037beaae0f4685e6ac4117764f67169bb29 /net/netfilter/xt_time.c | |
parent | 7caa56f006e9d712b44f27b32520c66420d5cbc6 (diff) | |
download | linux-916f6efae62305796e012e7c3a7884a267cbacbf.tar.xz |
netfilter: never get/set skb->tstamp
setting net.netfilter.nf_conntrack_timestamp=1 breaks xmit with fq
scheduler. skb->tstamp might be "refreshed" using ktime_get_real(),
but fq expects CLOCK_MONOTONIC.
This patch removes all places in netfilter that check/set skb->tstamp:
1. To fix the bogus "start" time seen with conntrack timestamping for
outgoing packets, never use skb->tstamp and always use current time.
2. In nfqueue and nflog, only use skb->tstamp for incoming packets,
as determined by current hook (prerouting, input, forward).
3. xt_time has to use system clock as well rather than skb->tstamp.
We could still use skb->tstamp for prerouting/input/foward, but
I see no advantage to make this conditional.
Fixes: fb420d5d91c1 ("tcp/fq: move back to CLOCK_MONOTONIC")
Cc: Eric Dumazet <edumazet@google.com>
Reported-by: Michal Soltys <soltys@ziu.info>
Signed-off-by: Florian Westphal <fw@strlen.de>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Diffstat (limited to 'net/netfilter/xt_time.c')
-rw-r--r-- | net/netfilter/xt_time.c | 23 |
1 files changed, 14 insertions, 9 deletions
diff --git a/net/netfilter/xt_time.c b/net/netfilter/xt_time.c index c13bcd0ab491..8dbb4d48f2ed 100644 --- a/net/netfilter/xt_time.c +++ b/net/netfilter/xt_time.c @@ -163,19 +163,24 @@ time_mt(const struct sk_buff *skb, struct xt_action_param *par) s64 stamp; /* - * We cannot use get_seconds() instead of __net_timestamp() here. + * We need real time here, but we can neither use skb->tstamp + * nor __net_timestamp(). + * + * skb->tstamp and skb->skb_mstamp_ns overlap, however, they + * use different clock types (real vs monotonic). + * * Suppose you have two rules: - * 1. match before 13:00 - * 2. match after 13:00 + * 1. match before 13:00 + * 2. match after 13:00 + * * If you match against processing time (get_seconds) it * may happen that the same packet matches both rules if - * it arrived at the right moment before 13:00. + * it arrived at the right moment before 13:00, so it would be + * better to check skb->tstamp and set it via __net_timestamp() + * if needed. This however breaks outgoing packets tx timestamp, + * and causes them to get delayed forever by fq packet scheduler. */ - if (skb->tstamp == 0) - __net_timestamp((struct sk_buff *)skb); - - stamp = ktime_to_ns(skb->tstamp); - stamp = div_s64(stamp, NSEC_PER_SEC); + stamp = get_seconds(); if (info->flags & XT_TIME_LOCAL_TZ) /* Adjust for local timezone */ |