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net: ipv4: avoid mixed n_redirects and rate_tokens usage
[ Upstream commitb406472b5a
] Since commitc09551c6ff
("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:1da177e4c3
("Linux-2.6.12-rc2") Fixes:c09551c6ff
("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>
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parent
33b301a1bd
commit
562c2ff7e3
1 changed files with 2 additions and 3 deletions
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@ -925,16 +925,15 @@ void ip_rt_send_redirect(struct sk_buff *skb)
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if (peer->rate_tokens == 0 ||
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time_after(jiffies,
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(peer->rate_last +
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(ip_rt_redirect_load << peer->rate_tokens)))) {
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(ip_rt_redirect_load << peer->n_redirects)))) {
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__be32 gw = rt_nexthop(rt, ip_hdr(skb)->daddr);
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icmp_send(skb, ICMP_REDIRECT, ICMP_REDIR_HOST, gw);
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peer->rate_last = jiffies;
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++peer->rate_tokens;
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++peer->n_redirects;
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#ifdef CONFIG_IP_ROUTE_VERBOSE
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if (log_martians &&
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peer->rate_tokens == ip_rt_redirect_number)
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peer->n_redirects == ip_rt_redirect_number)
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net_warn_ratelimited("host %pI4/if%d ignores redirects for %pI4 to %pI4\n",
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&ip_hdr(skb)->saddr, inet_iif(skb),
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&ip_hdr(skb)->daddr, &gw);
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