Messages in this thread |  | | From | Jonathan Maxwell <> | Date | Sun, 8 Jan 2023 10:46:09 +1100 | Subject | Re: [net-next] ipv6: fix routing cache overflow for raw sockets |
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On Sat, Jan 7, 2023 at 10:27 AM Andrea Mayer <andrea.mayer@uniroma2.it> wrote: > > Hi Jon, > please see after, thanks. > > > > > > Any chance you could test this patch based on the latest net-next > > > kernel and let me know the result? > > > > > > diff --git a/include/net/dst_ops.h b/include/net/dst_ops.h > > > index 88ff7bb2bb9b..632086b2f644 100644 > > > --- a/include/net/dst_ops.h > > > +++ b/include/net/dst_ops.h > > > @@ -16,7 +16,7 @@ struct dst_ops { > > > unsigned short family; > > > unsigned int gc_thresh; > > > > > > - int (*gc)(struct dst_ops *ops); > > > + void (*gc)(struct dst_ops *ops); > > > struct dst_entry * (*check)(struct dst_entry *, __u32 cookie); > > > unsigned int (*default_advmss)(const struct dst_entry *); > > > unsigned int (*mtu)(const struct dst_entry *); > > > diff --git a/net/core/dst.c b/net/core/dst.c > > > index 6d2dd03dafa8..31c08a3386d3 100644 > > > --- a/net/core/dst.c > > > +++ b/net/core/dst.c > > > @@ -82,12 +82,8 @@ void *dst_alloc(struct dst_ops *ops, struct net_device *dev, > > > > > > if (ops->gc && > > > !(flags & DST_NOCOUNT) && > > > - dst_entries_get_fast(ops) > ops->gc_thresh) { > > > - if (ops->gc(ops)) { > > > - pr_notice_ratelimited("Route cache is full: > > > consider increasing sysctl net.ipv6.route.max_size.\n"); > > > - return NULL; > > > - } > > > - } > > > + dst_entries_get_fast(ops) > ops->gc_thresh) > > > + ops->gc(ops); > > > > > > dst = kmem_cache_alloc(ops->kmem_cachep, GFP_ATOMIC); > > > if (!dst) > > > diff --git a/net/ipv6/route.c b/net/ipv6/route.c > > > index e74e0361fd92..b643dda68d31 100644 > > > --- a/net/ipv6/route.c > > > +++ b/net/ipv6/route.c > > > @@ -91,7 +91,7 @@ static struct dst_entry *ip6_negative_advice(struct > > > dst_entry *); > > > static void ip6_dst_destroy(struct dst_entry *); > > > static void ip6_dst_ifdown(struct dst_entry *, > > > struct net_device *dev, int how); > > > -static int ip6_dst_gc(struct dst_ops *ops); > > > +static void ip6_dst_gc(struct dst_ops *ops); > > > > > > static int ip6_pkt_discard(struct sk_buff *skb); > > > static int ip6_pkt_discard_out(struct net *net, struct > > > sock *sk, struct sk_buff *skb); > > > @@ -3284,11 +3284,10 @@ struct dst_entry *icmp6_dst_alloc(struct > > > net_device *dev, > > > return dst; > > > } > > > > > > -static int ip6_dst_gc(struct dst_ops *ops) > > > +static void ip6_dst_gc(struct dst_ops *ops) > > > { > > > struct net *net = container_of(ops, struct net, ipv6.ip6_dst_ops); > > > int rt_min_interval = net->ipv6.sysctl.ip6_rt_gc_min_interval; > > > - int rt_max_size = net->ipv6.sysctl.ip6_rt_max_size; > > > int rt_elasticity = net->ipv6.sysctl.ip6_rt_gc_elasticity; > > > int rt_gc_timeout = net->ipv6.sysctl.ip6_rt_gc_timeout; > > > unsigned long rt_last_gc = net->ipv6.ip6_rt_last_gc; > > > @@ -3296,11 +3295,10 @@ static int ip6_dst_gc(struct dst_ops *ops) > > > int entries; > > > > > > entries = dst_entries_get_fast(ops); > > > - if (entries > rt_max_size) > > > + if (entries > ops->gc_thresh) > > > entries = dst_entries_get_slow(ops); > > > > > > - if (time_after(rt_last_gc + rt_min_interval, jiffies) && > > > - entries <= rt_max_size) > > > + if (time_after(rt_last_gc + rt_min_interval, jiffies)) > > > goto out; > > > > > > fib6_run_gc(atomic_inc_return(&net->ipv6.ip6_rt_gc_expire), net, true); > > > @@ -3310,7 +3308,6 @@ static int ip6_dst_gc(struct dst_ops *ops) > > > out: > > > val = atomic_read(&net->ipv6.ip6_rt_gc_expire); > > > atomic_set(&net->ipv6.ip6_rt_gc_expire, val - (val >> rt_elasticity)); > > > - return entries > rt_max_size; > > > } > > > > > > static int ip6_nh_lookup_table(struct net *net, struct fib6_config *cfg, > > > @@ -6512,7 +6509,7 @@ static int __net_init ip6_route_net_init(struct net *net) > > > #endif > > > > > > net->ipv6.sysctl.flush_delay = 0; > > > - net->ipv6.sysctl.ip6_rt_max_size = 4096; > > > + net->ipv6.sysctl.ip6_rt_max_size = INT_MAX; > > > net->ipv6.sysctl.ip6_rt_gc_min_interval = HZ / 2; > > > net->ipv6.sysctl.ip6_rt_gc_timeout = 60*HZ; > > > net->ipv6.sysctl.ip6_rt_gc_interval = 30*HZ; > > > > > > > Yes, I will apply this patch in the next days and check how it deals with the > > seg6 subsystem. I will keep you posted. > > > > I applied the patch* to the net-next (HEAD 6bd4755c7c49) and did some tests on > the seg6 subsystem, specifically running the End.X/DX6 behaviors. They seem to > work fine.
Thanks Andrea much appreciated. It worked fine in my raw socket tests as well. I'll look at submitting it soon.
> > (*) I had to slightly edit the patch because of the code formatting, e.g. > some incorrect line breaks, spaces, etc. >
Sorry about that, I should have sent it from git to avoid that.
Regards
Jon
> Ciao, > Andrea > > > > > > On Sat, Dec 24, 2022 at 6:38 PM Jonathan Maxwell <jmaxwell37@gmail.com> wrote: > > > > > > > > On Sat, Dec 24, 2022 at 7:28 AM Andrea Mayer <andrea.mayer@uniroma2.it> wrote: > > > > > > > > > > Hi Jon, > > > > > please see below, thanks. > > > > > > > > > > On Wed, 21 Dec 2022 08:48:11 +1100 > > > > > Jonathan Maxwell <jmaxwell37@gmail.com> wrote: > > > > > > > > > > > On Tue, Dec 20, 2022 at 11:35 PM Paolo Abeni <pabeni@redhat.com> wrote: > > > > > > > > > > > > > > On Mon, 2022-12-19 at 10:48 +1100, Jon Maxwell wrote: > > > > > > > > Sending Ipv6 packets in a loop via a raw socket triggers an issue where a > > > > > > > > route is cloned by ip6_rt_cache_alloc() for each packet sent. This quickly > > > > > > > > consumes the Ipv6 max_size threshold which defaults to 4096 resulting in > > > > > > > > these warnings: > > > > > > > > > > > > > > > > [1] 99.187805] dst_alloc: 7728 callbacks suppressed > > > > > > > > [2] Route cache is full: consider increasing sysctl net.ipv6.route.max_size. > > > > > > > > . > > > > > > > > . > > > > > > > > [300] Route cache is full: consider increasing sysctl net.ipv6.route.max_size. > > > > > > > > > > > > > > If I read correctly, the maximum number of dst that the raw socket can > > > > > > > use this way is limited by the number of packets it allows via the > > > > > > > sndbuf limit, right? > > > > > > > > > > > > > > > > > > > Yes, but in my test sndbuf limit is never hit so it clones a route for > > > > > > every packet. > > > > > > > > > > > > e.g: > > > > > > > > > > > > output from C program sending 5000000 packets via a raw socket. > > > > > > > > > > > > ip raw: total num pkts 5000000 > > > > > > > > > > > > # bpftrace -e 'kprobe:dst_alloc {@count[comm] = count()}' > > > > > > Attaching 1 probe... > > > > > > > > > > > > @count[a.out]: 5000009 > > > > > > > > > > > > > Are other FLOWI_FLAG_KNOWN_NH users affected, too? e.g. nf_dup_ipv6, > > > > > > > ipvs, seg6? > > > > > > > > > > > > > > > > > > > Any call to ip6_pol_route(s) where no res.nh->fib_nh_gw_family is 0 can do it. > > > > > > But we have only seen this for raw sockets so far. > > > > > > > > > > > > > > > > In the SRv6 subsystem, the seg6_lookup_nexthop() is used by some > > > > > cross-connecting behaviors such as End.X and End.DX6 to forward traffic to a > > > > > specified nexthop. SRv6 End.X/DX6 can specify an IPv6 DA (i.e., a nexthop) > > > > > different from the one carried by the IPv6 header. For this purpose, > > > > > seg6_lookup_nexthop() sets the FLOWI_FLAG_KNOWN_NH. > > > > > > > > > Hi Andrea, > > > > > > > > Thanks for pointing that datapath out. The more generic approach we are > > > > taking bringing Ipv6 closer to Ipv4 in this regard should fix all instances > > > > of this. > > > > > > > > > > > > [1] 99.187805] dst_alloc: 7728 callbacks suppressed > > > > > > > > [2] Route cache is full: consider increasing sysctl net.ipv6.route.max_size. > > > > > > > > . > > > > > > > > . > > > > > > > > [300] Route cache is full: consider increasing sysctl net.ipv6.route.max_size. > > > > > > > > > > I can reproduce the same warning messages reported by you, by instantiating an > > > > > End.X behavior whose nexthop is handled by a route for which there is no "via". > > > > > In this configuration, the ip6_pol_route() (called by seg6_lookup_nexthop()) > > > > > triggers ip6_rt_cache_alloc() because i) the FLOWI_FLAG_KNOWN_NH is present ii) > > > > > and the res.nh->fib_nh_gw_family is 0 (as already pointed out). > > > > > > > > > > > > > Nice, when I get back after the holiday break I'll submit the next patch. It > > > > would be great if you could test the new patch and let me know how it works in > > > > your tests at that juncture. I'll keep you posted. > > > > > > > > Regards > > > > > > > > Jon > > > > > > > > > > Regards > > > > > > > > > > > > Jon > > > > > > > > > > Ciao, > > > > > Andrea > > > > > > -- > > Andrea Mayer <andrea.mayer@uniroma2.it> > > > -- > Andrea Mayer <andrea.mayer@uniroma2.it>
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