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authorPaolo Abeni <pabeni@redhat.com>2020-05-08 19:28:34 +0200
committerJakub Kicinski <kuba@kernel.org>2020-05-08 22:52:57 -0700
commit57644431a6c2faac5d754ebd35780cf43a531b1a (patch)
tree13cdf95f875974db0c04606c580fa9bd999edfd8 /net/ipv4/route.c
parent9302bead664f49ef73040fa06fa64552d02fee42 (diff)
net: ipv4: really enforce backoff for redirects
In commit b406472b5ad7 ("net: ipv4: avoid mixed n_redirects and rate_tokens usage") I missed the fact that a 0 'rate_tokens' will bypass the backoff algorithm. Since rate_tokens is cleared after a redirect silence, and never incremented on redirects, if the host keeps receiving packets requiring redirect it will reply ignoring the backoff. Additionally, the 'rate_last' field will be updated with the cadence of the ingress packet requiring redirect. If that rate is high enough, that will prevent the host from generating any other kind of ICMP messages The check for a zero 'rate_tokens' value was likely a shortcut to avoid the more complex backoff algorithm after a redirect silence period. Address the issue checking for 'n_redirects' instead, which is incremented on successful redirect, and does not interfere with other ICMP replies. Fixes: b406472b5ad7 ("net: ipv4: avoid mixed n_redirects and rate_tokens usage") Reported-and-tested-by: Colin Walters <walters@redhat.com> Signed-off-by: Paolo Abeni <pabeni@redhat.com> Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'net/ipv4/route.c')
-rw-r--r--net/ipv4/route.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index 788c69d9bfe0..fa829f31a3f5 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -915,7 +915,7 @@ void ip_rt_send_redirect(struct sk_buff *skb)
/* Check for load limit; set rate_last to the latest sent
* redirect.
*/
- if (peer->rate_tokens == 0 ||
+ if (peer->n_redirects == 0 ||
time_after(jiffies,
(peer->rate_last +
(ip_rt_redirect_load << peer->n_redirects)))) {