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authorPaolo Abeni <pabeni@redhat.com>2019-10-04 15:11:17 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2019-10-07 18:57:21 +0200
commit124b64feafa9c3825d8b6834d34dbdc6d7fd9b13 (patch)
tree580054720bcf2ac238e2918c6cb671bd8e5e9d62
parent6f8564edf8c193cfc59dcb68dd7d7297f9a72f39 (diff)
net: ipv4: avoid mixed n_redirects and rate_tokens usage
[ Upstream commit b406472b5ad79ede8d10077f0c8f05505ace8b6d ] 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> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--net/ipv4/route.c5
1 files changed, 2 insertions, 3 deletions
diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index 232581c140a0..7065d68086ab 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -908,16 +908,15 @@ 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);