linux-kernel - Re: [PATCH v2] netfilter: account ebt_table

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Message-ID: <5cc8efad-9d3d-3136-3ddc-1f8a640cb1f8@virtuozzo.com>
Date:   Sun, 6 Jan 2019 11:00:24 +0000
From:   Kirill Tkhai <ktkhai@...tuozzo.com>
To:     Shakeel Butt <shakeelb@...gle.com>,
        Michal Hocko <mhocko@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Florian Westphal <fw@...len.de>
CC:     "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "syzbot+7713f3aa67be76b1552c@...kaller.appspotmail.com" 
        <syzbot+7713f3aa67be76b1552c@...kaller.appspotmail.com>,
        Pablo Neira Ayuso <pablo@...filter.org>,
        Jozsef Kadlecsik <kadlec@...ckhole.kfki.hu>,
        Roopa Prabhu <roopa@...ulusnetworks.com>,
        Nikolay Aleksandrov <nikolay@...ulusnetworks.com>,
        "netfilter-devel@...r.kernel.org" <netfilter-devel@...r.kernel.org>,
        "coreteam@...filter.org" <coreteam@...filter.org>,
        "bridge@...ts.linux-foundation.org" 
        <bridge@...ts.linux-foundation.org>
Subject: Re: [PATCH v2] netfilter: account ebt_table_info to kmemcg

On 03.01.2019 06:14, Shakeel Butt wrote:
> The [ip,ip6,arp]_tables use x_tables_info internally and the underlying
> memory is already accounted to kmemcg. Do the same for ebtables. The
> syzbot, by using setsockopt(EBT_SO_SET_ENTRIES), was able to OOM the
> whole system from a restricted memcg, a potential DoS.
> 
> By accounting the ebt_table_info, the memory used for ebt_table_info can
> be contained within the memcg of the allocating process. However the
> lifetime of ebt_table_info is independent of the allocating process and
> is tied to the network namespace. So, the oom-killer will not be able to
> relieve the memory pressure due to ebt_table_info memory. The memory for
> ebt_table_info is allocated through vmalloc. Currently vmalloc does not
> handle the oom-killed allocating process correctly and one large
> allocation can bypass memcg limit enforcement. So, with this patch,
> at least the small allocations will be contained. For large allocations,
> we need to fix vmalloc.
> 
> Reported-by: syzbot+7713f3aa67be76b1552c@...kaller.appspotmail.com
> Signed-off-by: Shakeel Butt <shakeelb@...gle.com>
> Cc: Florian Westphal <fw@...len.de>
> Cc: Michal Hocko <mhocko@...nel.org>
> Cc: Kirill Tkhai <ktkhai@...tuozzo.com>
> Cc: Pablo Neira Ayuso <pablo@...filter.org>
> Cc: Jozsef Kadlecsik <kadlec@...ckhole.kfki.hu>
> Cc: Roopa Prabhu <roopa@...ulusnetworks.com>
> Cc: Nikolay Aleksandrov <nikolay@...ulusnetworks.com>
> Cc: Andrew Morton <akpm@...ux-foundation.org>
> Cc: Linux MM <linux-mm@...ck.org>
> Cc: netfilter-devel@...r.kernel.org
> Cc: coreteam@...filter.org
> Cc: bridge@...ts.linux-foundation.org
> Cc: LKML <linux-kernel@...r.kernel.org>
> ---
> Changelog since v1:
> - More descriptive commit message.

Reviewed-by: Kirill Tkhai <ktkhai@...tuozzo.com>

> 
>  net/bridge/netfilter/ebtables.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/net/bridge/netfilter/ebtables.c b/net/bridge/netfilter/ebtables.c
> index 491828713e0b..5e55cef0cec3 100644
> --- a/net/bridge/netfilter/ebtables.c
> +++ b/net/bridge/netfilter/ebtables.c
> @@ -1137,14 +1137,16 @@ static int do_replace(struct net *net, const void __user *user,
>  	tmp.name[sizeof(tmp.name) - 1] = 0;
>  
>  	countersize = COUNTER_OFFSET(tmp.nentries) * nr_cpu_ids;
> -	newinfo = vmalloc(sizeof(*newinfo) + countersize);
> +	newinfo = __vmalloc(sizeof(*newinfo) + countersize, GFP_KERNEL_ACCOUNT,
> +			    PAGE_KERNEL);
>  	if (!newinfo)
>  		return -ENOMEM;
>  
>  	if (countersize)
>  		memset(newinfo->counters, 0, countersize);
>  
> -	newinfo->entries = vmalloc(tmp.entries_size);
> +	newinfo->entries = __vmalloc(tmp.entries_size, GFP_KERNEL_ACCOUNT,
> +				     PAGE_KERNEL);
>  	if (!newinfo->entries) {
>  		ret = -ENOMEM;
>  		goto free_newinfo;
>