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Message-ID: <1389337306.31367.94.camel@edumazet-glaptop2.roam.corp.google.com>
Date: Thu, 09 Jan 2014 23:01:46 -0800
From: Eric Dumazet <eric.dumazet@...il.com>
To: Hannes Frederic Sowa <hannes@...essinduktion.org>
Cc: Bob Falken <NetFestivalHaveFun@....com>,
Julian Anastasov <ja@....bg>, netdev@...r.kernel.org,
kaber@...sh.net, tgraf@...g.ch
Subject: Re: Multicast routing stops functioning after 4G multicast packets
recived.
On Fri, 2014-01-10 at 07:36 +0100, Hannes Frederic Sowa wrote:
> Ok, so I am proposing this patch. Only difference from the RFC is that
> I removed the superfluous arg.rule NULL-pointer checks (I hate if they
> are superfluous and they always seem to spread ;) ).
>
> Maybe you could test this one instead and David could pick it up as soon
> as your results are in.
>
> I'll also look for the stable kernels where FIB_LOOKUP_NOREF is not
> yet available.
>
> Thank you,
>
> Hannes
>
> [PATCH net] net: avoid reference counter overflows on fib_rules in multicast forwarding
>
> When introducing multiple table support for multicast forwarding in
> IPv4 and IPv6, necessary fib_rules_put reference count decrements were
> forgotten.
>
> Bob Falken reported that after 4G packets, multicast forwarding stopped
> working. This was because of a rule reference counter overflow which
> freed the rule as soon as the overflow happend.
>
> So, use FIB_LOOKUP_NOREF if we are already in a RCU protected section and
> correctly deal with reference counter if not (called from ndo_start_xmit).
>
> Fixes: f0ad0860d01e47 ("ipv4: ipmr: support multiple tables")
> Fixes: d1db275dd3f6e4 ("ipv6: ip6mr: support multiple tables")
> Reported-by: Bob Falken <NetFestivalHaveFun@....com>
> Cc: Patrick McHardy <kaber@...sh.net>
> Cc: Thomas Graf <tgraf@...g.ch>
> Cc: Julian Anastasov <ja@....bg>
> Cc: Eric Dumazet <eric.dumazet@...il.com>
> Signed-off-by: Hannes Frederic Sowa <hannes@...essinduktion.org>
> ---
> net/ipv4/ipmr.c | 23 +++++++++++++++++------
> net/ipv6/ip6mr.c | 21 +++++++++++++++------
> 2 files changed, 32 insertions(+), 12 deletions(-)
>
> diff --git a/net/ipv4/ipmr.c b/net/ipv4/ipmr.c
> index 421a249..c8d0857 100644
> --- a/net/ipv4/ipmr.c
> +++ b/net/ipv4/ipmr.c
> @@ -157,9 +157,12 @@ static struct mr_table *ipmr_get_table(struct net *net, u32 id)
> static int ipmr_fib_lookup(struct net *net, struct flowi4 *flp4,
> struct mr_table **mrt)
> {
> - struct ipmr_result res;
> - struct fib_lookup_arg arg = { .result = &res, };
> int err;
> + struct ipmr_result res;
> + struct fib_lookup_arg arg = {
> + .result = &res,
> + .flags = FIB_LOOKUP_NOREF,
> + };
>
> err = fib_rules_lookup(net->ipv4.mr_rules_ops,
> flowi4_to_flowi(flp4), 0, &arg);
> @@ -448,16 +451,22 @@ failure:
>
> static netdev_tx_t reg_vif_xmit(struct sk_buff *skb, struct net_device *dev)
> {
> + int err;
> + struct ipmr_result res;
> struct net *net = dev_net(dev);
> - struct mr_table *mrt;
> +
> + struct fib_lookup_arg arg = {
> + .result = &res,
> + };
> +
> struct flowi4 fl4 = {
> .flowi4_oif = dev->ifindex,
> .flowi4_iif = skb->skb_iif,
> .flowi4_mark = skb->mark,
> };
> - int err;
>
> - err = ipmr_fib_lookup(net, &fl4, &mrt);
> + err = fib_rules_lookup(net->ipv4.mr_rules_ops,
> + flowi4_to_flowi(&fl4), 0, &arg);
Its not clear to me why you expand ipmr_fib_lookup()
Is there something wrong with existing code ?
Its not mentioned in changelog
> if (err < 0) {
> kfree_skb(skb);
> return err;
> @@ -466,9 +475,11 @@ static netdev_tx_t reg_vif_xmit(struct sk_buff *skb, struct net_device *dev)
> read_lock(&mrt_lock);
> dev->stats.tx_bytes += skb->len;
> dev->stats.tx_packets++;
> - ipmr_cache_report(mrt, skb, mrt->mroute_reg_vif_num, IGMPMSG_WHOLEPKT);
> + ipmr_cache_report(res.mrt, skb, res.mrt->mroute_reg_vif_num,
> + IGMPMSG_WHOLEPKT);
> read_unlock(&mrt_lock);
> kfree_skb(skb);
> + fib_rule_put(arg.rule);
This is the one line that is really missing, patch could be smaller.
> return NETDEV_TX_OK;
> }
>
> diff --git a/net/ipv6/ip6mr.c b/net/ipv6/ip6mr.c
> index f365310..38347a3 100644
> --- a/net/ipv6/ip6mr.c
> +++ b/net/ipv6/ip6mr.c
> @@ -141,9 +141,12 @@ static struct mr6_table *ip6mr_get_table(struct net *net, u32 id)
> static int ip6mr_fib_lookup(struct net *net, struct flowi6 *flp6,
> struct mr6_table **mrt)
> {
> - struct ip6mr_result res;
> - struct fib_lookup_arg arg = { .result = &res, };
> int err;
> + struct ip6mr_result res;
> + struct fib_lookup_arg arg = {
> + .result = &res,
> + .flags = FIB_LOOKUP_NOREF,
> + };
>
> err = fib_rules_lookup(net->ipv6.mr6_rules_ops,
> flowi6_to_flowi(flp6), 0, &arg);
> @@ -693,16 +696,20 @@ static const struct inet6_protocol pim6_protocol = {
> static netdev_tx_t reg_vif_xmit(struct sk_buff *skb,
> struct net_device *dev)
> {
> + int err;
> + struct ip6mr_result res;
> struct net *net = dev_net(dev);
> - struct mr6_table *mrt;
> struct flowi6 fl6 = {
> .flowi6_oif = dev->ifindex,
> .flowi6_iif = skb->skb_iif,
> .flowi6_mark = skb->mark,
> };
> - int err;
> + struct fib_lookup_arg arg = {
> + .result = &res,
> + };
>
> - err = ip6mr_fib_lookup(net, &fl6, &mrt);
> + err = fib_rules_lookup(net->ipv6.mr6_rules_ops,
> + flowi6_to_flowi(&fl6), 0, &arg);
same remark here.
> if (err < 0) {
> kfree_skb(skb);
> return err;
> @@ -711,9 +718,11 @@ static netdev_tx_t reg_vif_xmit(struct sk_buff *skb,
> read_lock(&mrt_lock);
> dev->stats.tx_bytes += skb->len;
> dev->stats.tx_packets++;
> - ip6mr_cache_report(mrt, skb, mrt->mroute_reg_vif_num, MRT6MSG_WHOLEPKT);
> + ip6mr_cache_report(res.mrt, skb, res.mrt->mroute_reg_vif_num,
> + MRT6MSG_WHOLEPKT);
> read_unlock(&mrt_lock);
> kfree_skb(skb);
> + fib_rule_put(arg.rule);
> return NETDEV_TX_OK;
> }
>
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