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Date: Thu, 31 Jul 2014 16:34:07 +0800
From: Duan Jiong <duanj.fnst@...fujitsu.com>
To: Hannes Frederic Sowa <hannes@...essinduktion.org>
CC: David Miller <davem@...emloft.net>, <eric.dumazet@...il.com>,
netdev <netdev@...r.kernel.org>
Subject: Re: [PATCH] net: fix the counter ICMP_MIB_INERRORS/ICMP6_MIB_INERRORS
On 07/31/2014 03:52 PM, Hannes Frederic Sowa wrote:
> On Do, 2014-07-31 at 10:58 +0800, Duan Jiong wrote:
>> On 07/30/2014 09:45 PM, Hannes Frederic Sowa wrote:
>>> On Di, 2014-07-29 at 16:19 +0800, Duan Jiong wrote:
>>>> When dealing with ICMPv[46] Error Message, function icmp_socket_deliver()
>>>> and icmpv6_notify() do some valid checks on packet's length, but then some
>>>> protocols check packet's length redaudantly. So remove those duplicated
>>>> statements, and increase counter ICMP_MIB_INERRORS/ICMP6_MIB_INERRORS in
>>>> function icmp_socket_deliver() and icmpv6_notify() respectively.
>>>>
>>>> In addition, add missed counter in udp6/udplite6 when socket is NULL.
>>>
>>> I am ok with adding the error counters, but...
>>>
>>>> ---
>>>> net/ipv4/icmp.c | 4 +++-
>>>> net/ipv4/tcp_ipv4.c | 5 -----
>>>> net/ipv6/icmp.c | 11 ++++++++---
>>>> net/ipv6/udp.c | 8 ++++++--
>>>> net/sctp/input.c | 5 -----
>>>> 5 files changed, 17 insertions(+), 16 deletions(-)
>>>>
>>>> diff --git a/net/ipv4/icmp.c b/net/ipv4/icmp.c
>>>> index 42b7bcf..092400e 100644
>>>> --- a/net/ipv4/icmp.c
>>>> +++ b/net/ipv4/icmp.c
>>>> @@ -663,8 +663,10 @@ static void icmp_socket_deliver(struct sk_buff *skb, u32 info)
>>>> /* Checkin full IP header plus 8 bytes of protocol to
>>>> * avoid additional coding at protocol handlers.
>>>> */
>>>> - if (!pskb_may_pull(skb, iph->ihl * 4 + 8))
>>>> + if (!pskb_may_pull(skb, iph->ihl * 4 + 8)) {
>>>> + ICMP_INC_STATS_BH(dev_net(skb->dev), ICMP_MIB_INERRORS);
>>>> return;
>>>> + }
>>>>
>>>> raw_icmp_error(skb, protocol, info);
>>>>
>>>> diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
>>>> index 77cccda..715cf6b 100644
>>>> --- a/net/ipv4/tcp_ipv4.c
>>>> +++ b/net/ipv4/tcp_ipv4.c
>>>> @@ -342,11 +342,6 @@ void tcp_v4_err(struct sk_buff *icmp_skb, u32 info)
>>>> int err;
>>>> struct net *net = dev_net(icmp_skb->dev);
>>>>
>>>> - if (icmp_skb->len < (iph->ihl << 2) + 8) {
>>>> - ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS);
>>>> - return;
>>>> - }
>>>> -
>>>> sk = inet_lookup(net, &tcp_hashinfo, iph->daddr, th->dest,
>>>> iph->saddr, th->source, inet_iif(icmp_skb));
>>>> if (!sk) {
>>>> diff --git a/net/ipv6/icmp.c b/net/ipv6/icmp.c
>>>> index f6c84a6..8ca3cc0 100644
>>>> --- a/net/ipv6/icmp.c
>>>> +++ b/net/ipv6/icmp.c
>>>> @@ -626,9 +626,10 @@ void icmpv6_notify(struct sk_buff *skb, u8 type, u8 code, __be32 info)
>>>> int inner_offset;
>>>> __be16 frag_off;
>>>> u8 nexthdr;
>>>> + struct net *net = dev_net(skb->dev);
>>>>
>>>> if (!pskb_may_pull(skb, sizeof(struct ipv6hdr)))
>>>> - return;
>>>> + goto out;
>>>>
>>>> nexthdr = ((struct ipv6hdr *)skb->data)->nexthdr;
>>>> if (ipv6_ext_hdr(nexthdr)) {
>>>> @@ -636,14 +637,14 @@ void icmpv6_notify(struct sk_buff *skb, u8 type, u8 code, __be32 info)
>>>> inner_offset = ipv6_skip_exthdr(skb, sizeof(struct ipv6hdr),
>>>> &nexthdr, &frag_off);
>>>> if (inner_offset<0)
>>>> - return;
>>>> + goto out;
>>>> } else {
>>>> inner_offset = sizeof(struct ipv6hdr);
>>>> }
>>>>
>>>> /* Checkin header including 8 bytes of inner protocol header. */
>>>> if (!pskb_may_pull(skb, inner_offset+8))
>>>> - return;
>>>> + goto out;
>>>>
>>>> /* BUGGG_FUTURE: we should try to parse exthdrs in this packet.
>>>> Without this we will not able f.e. to make source routed
>>>> @@ -659,6 +660,10 @@ void icmpv6_notify(struct sk_buff *skb, u8 type, u8 code, __be32 info)
>>>> rcu_read_unlock();
>>>>
>>>> raw6_icmp_error(skb, nexthdr, type, code, inner_offset, info);
>>>> + return;
>>>> +
>>>> +out:
>>>> + ICMP6_INC_STATS_BH(net, __in6_dev_get(skb->dev), ICMP6_MIB_INERRORS);
>>>
>>> ... please don't use __in6_dev_get in BH without rcu, but inet6_iif. You
>>> risk a lockdep error otherwise. You don't have rtnl locked and no RCU
>>> read lock.
>>>
>>
>> May be we can use in6_dev_get instead of __in6_dev_get, and
>> use in6_dev_put to release the reference later.
>
> Sure, you can. You can also protect the update of the counter with an
> rcu read lock, but you won't find anything easier than inet6_iif. ;)
Are you sure using inet6_iif is fine?
function inet6_iif() return int, but we need struct inet6_dev *.
Thanks,
Duan
>
>>>> }
>>>>
>>>> /*
>>>> diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
>>>> index 7092ff7..f13d297 100644
>>>> --- a/net/ipv6/udp.c
>>>> +++ b/net/ipv6/udp.c
>>>> @@ -534,11 +534,15 @@ void __udp6_lib_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
>>>> struct udphdr *uh = (struct udphdr*)(skb->data+offset);
>>>> struct sock *sk;
>>>> int err;
>>>> + struct net *net = dev_net(skb->dev);
>>>>
>>>> - sk = __udp6_lib_lookup(dev_net(skb->dev), daddr, uh->dest,
>>>> + sk = __udp6_lib_lookup(net, daddr, uh->dest,
>>>> saddr, uh->source, inet6_iif(skb), udptable);
>>>> - if (sk == NULL)
>>>> + if (sk == NULL) {
>>>> + ICMP6_INC_STATS_BH(net, __in6_dev_get(skb->dev),
>>>> + ICMP6_MIB_INERRORS);
>>>
>>> It is not really necessary here, as you like.
>>>
>>
>> I add it just because i saw the same statements in dccp6/sctp6/tcp6 error
>> handler.
>
> Counting errors here is fine. And because you are have rcu read lock the
> __in6_dev_get is also fine.
>
> Bye,
> Hannes
>
>
> .
>
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