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| author | Paolo Abeni <pabeni@redhat.com> | 2019-10-04 15:11:17 +0200 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2019-10-04 17:27:04 -0700 |
| commit | b406472b5ad79ede8d10077f0c8f05505ace8b6d (patch) | |
| tree | e68b820360cf0a2f45dcba1d2a13a0f18a06cd61 /net/ipv4/route.c | |
| parent | a54cdeeb04fc719e4c7f19d6e28dba7ea86cee5b (diff) | |
| download | lwn-b406472b5ad79ede8d10077f0c8f05505ace8b6d.tar.gz lwn-b406472b5ad79ede8d10077f0c8f05505ace8b6d.zip | |
net: ipv4: avoid mixed n_redirects and rate_tokens usage
Since commit c09551c6ff7f ("net: ipv4: use a dedicated counter
for icmp_v4 redirect packets") we use 'n_redirects' to account
for redirect packets, but we still use 'rate_tokens' to compute
the redirect packets exponential backoff.
If the device sent to the relevant peer any ICMP error packet
after sending a redirect, it will also update 'rate_token' according
to the leaking bucket schema; typically 'rate_token' will raise
above BITS_PER_LONG and the redirect packets backoff algorithm
will produce undefined behavior.
Fix the issue using 'n_redirects' to compute the exponential backoff
in ip_rt_send_redirect().
Note that we still clear rate_tokens after a redirect silence period,
to avoid changing an established behaviour.
The root cause predates git history; before the mentioned commit in
the critical scenario, the kernel stopped sending redirects, after
the mentioned commit the behavior more randomic.
Reported-by: Xiumei Mu <xmu@redhat.com>
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Fixes: c09551c6ff7f ("net: ipv4: use a dedicated counter for icmp_v4 redirect packets")
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Acked-by: Lorenzo Bianconi <lorenzo.bianconi@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4/route.c')
| -rw-r--r-- | net/ipv4/route.c | 5 |
1 files changed, 2 insertions, 3 deletions
diff --git a/net/ipv4/route.c b/net/ipv4/route.c index 7dcce724c78b..14654876127e 100644 --- a/net/ipv4/route.c +++ b/net/ipv4/route.c @@ -916,16 +916,15 @@ void ip_rt_send_redirect(struct sk_buff *skb) if (peer->rate_tokens == 0 || time_after(jiffies, (peer->rate_last + - (ip_rt_redirect_load << peer->rate_tokens)))) { + (ip_rt_redirect_load << peer->n_redirects)))) { __be32 gw = rt_nexthop(rt, ip_hdr(skb)->daddr); icmp_send(skb, ICMP_REDIRECT, ICMP_REDIR_HOST, gw); peer->rate_last = jiffies; - ++peer->rate_tokens; ++peer->n_redirects; #ifdef CONFIG_IP_ROUTE_VERBOSE if (log_martians && - peer->rate_tokens == ip_rt_redirect_number) + peer->n_redirects == ip_rt_redirect_number) net_warn_ratelimited("host %pI4/if%d ignores redirects for %pI4 to %pI4\n", &ip_hdr(skb)->saddr, inet_iif(skb), &ip_hdr(skb)->daddr, &gw); |