| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-Id: <20230112214140.b490f5e77e46d9cdab53d2b2@uniroma2.it>
Date: Thu, 12 Jan 2023 21:41:40 +0100
From: Andrea Mayer <andrea.mayer@...roma2.it>
To: Jon Maxwell <jmaxwell37@...il.com>
Cc: davem@...emloft.net, edumazet@...gle.com, kuba@...nel.org,
pabeni@...hat.com, yoshfuji@...ux-ipv6.org, dsahern@...nel.org,
martin.lau@...nel.org, joel@...lfernandes.org, paulmck@...nel.org,
eyal.birger@...il.com, netdev@...r.kernel.org,
linux-kernel@...r.kernel.org,
Andrea Mayer <andrea.mayer@...roma2.it>
Subject: Re: [net-next v2] ipv6: remove max_size check inline with ipv4
Hi Jon,
On Thu, 12 Jan 2023 12:25:32 +1100
Jon Maxwell <jmaxwell37@...il.com> wrote:
> v2: Correct syntax error in net/ipv6/route.c
>
> In ip6_dst_gc() replace:
>
> if (entries > gc_thresh)
>
> With:
>
> if (entries > ops->gc_thresh)
>
> 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.
>
> When this happens the packet is dropped and sendto() gets a network is
> unreachable error:
>
> # ./a.out -s
>
> remaining pkt 200557 errno 101
> remaining pkt 196462 errno 101
> .
> .
> remaining pkt 126821 errno 101
>
> Implement David Aherns suggestion to remove max_size check seeing that Ipv6
> has a GC to manage memory usage. Ipv4 already does not check max_size.
>
> Here are some memory comparisons for Ipv4 vs Ipv6 with the patch:
>
> Test by running 5 instances of a program that sends UDP packets to a raw
> socket 5000000 times. Compare Ipv4 and Ipv6 performance with a similar
> program.
>
> Ipv4:
>
is it supposed to be Ipv6, right?
Ciao,
Andrea
> Before test:
>
> # grep -e Slab -e Free /proc/meminfo
> MemFree: 29427108 kB
> Slab: 237612 kB
>
> # grep dst_cache /proc/slabinfo
> ip6_dst_cache 1912 2528 256 32 2 : tunables 0 0 0
> xfrm_dst_cache 0 0 320 25 2 : tunables 0 0 0
> ip_dst_cache 2881 3990 192 42 2 : tunables 0 0 0
>
> During test:
>
> # grep -e Slab -e Free /proc/meminfo
> MemFree: 29417608 kB
> Slab: 247712 kB
>
> # grep dst_cache /proc/slabinfo
> ip6_dst_cache 1912 2528 256 32 2 : tunables 0 0 0
> xfrm_dst_cache 0 0 320 25 2 : tunables 0 0 0
> ip_dst_cache 44394 44394 192 42 2 : tunables 0 0 0
>
> After test:
>
> # grep -e Slab -e Free /proc/meminfo
> MemFree: 29422308 kB
> Slab: 238104 kB
>
> # grep dst_cache /proc/slabinfo
> ip6_dst_cache 1912 2528 256 32 2 : tunables 0 0 0
> xfrm_dst_cache 0 0 320 25 2 : tunables 0 0 0
> ip_dst_cache 3048 4116 192 42 2 : tunables 0 0 0
>
> Ipv6 with patch:
>
> Errno 101 errors are not observed anymore with the patch.
>
> Before test:
>
> # grep -e Slab -e Free /proc/meminfo
> MemFree: 29422308 kB
> Slab: 238104 kB
>
> # grep dst_cache /proc/slabinfo
> ip6_dst_cache 1912 2528 256 32 2 : tunables 0 0 0
> xfrm_dst_cache 0 0 320 25 2 : tunables 0 0 0
> ip_dst_cache 3048 4116 192 42 2 : tunables 0 0 0
>
> During Test:
>
> # grep -e Slab -e Free /proc/meminfo
> MemFree: 29431516 kB
> Slab: 240940 kB
>
> # grep dst_cache /proc/slabinfo
> ip6_dst_cache 11980 12064 256 32 2 : tunables 0 0 0
> xfrm_dst_cache 0 0 320 25 2 : tunables 0 0 0
> ip_dst_cache 3048 4116 192 42 2 : tunables 0 0 0
>
> After Test:
>
> # grep -e Slab -e Free /proc/meminfo
> MemFree: 29441816 kB
> Slab: 238132 kB
>
> # grep dst_cache /proc/slabinfo
> ip6_dst_cache 1902 2432 256 32 2 : tunables 0 0 0
> xfrm_dst_cache 0 0 320 25 2 : tunables 0 0 0
> ip_dst_cache 3048 4116 192 42 2 : tunables 0 0 0
>
> Tested-by: Andrea Mayer <andrea.mayer@...roma2.it>
> Signed-off-by: Jon Maxwell <jmaxwell37@...il.com>
> ---
> include/net/dst_ops.h | 2 +-
> net/core/dst.c | 8 ++------
> net/ipv6/route.c | 13 +++++--------
> 3 files changed, 8 insertions(+), 15 deletions(-)
>
> 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;
> --
> 2.31.1
Powered by blists - more mailing lists