diff options
authorPaolo Abeni <pabeni@redhat.com>2019-10-04 15:11:17 +0200
committerDavid S. Miller <davem@davemloft.net>2019-10-04 17:27:04 -0700
commitb406472b5ad79ede8d10077f0c8f05505ace8b6d (patch)
parenta54cdeeb04fc719e4c7f19d6e28dba7ea86cee5b (diff)
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>
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 ||
(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;
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);