netdev - Re: [PATCH net] netfilter: complete validation of user input

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Message-ID: <ZhZanswJEPkqrlZE@calendula>
Date: Wed, 10 Apr 2024 11:23:42 +0200
From: Pablo Neira Ayuso <pablo@...filter.org>
To: Eric Dumazet <edumazet@...gle.com>
Cc: "David S . Miller" <davem@...emloft.net>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	Jozsef Kadlecsik <kadlec@...filter.org>, netdev@...r.kernel.org,
	netfilter-devel@...r.kernel.org, coreteam@...filter.org,
	eric.dumazet@...il.com, syzbot <syzkaller@...glegroups.com>
Subject: Re: [PATCH net] netfilter: complete validation of user input

On Tue, Apr 09, 2024 at 12:07:41PM +0000, Eric Dumazet wrote:
> In my recent commit, I missed that do_replace() handlers
> use copy_from_sockptr() (which I fixed), followed
> by unsafe copy_from_sockptr_offset() calls.

I forgot too to git grep away from net/netfilter/ folder for some
reason.

> In all functions, we can perform the @optlen validation
> before even calling xt_alloc_table_info() with the following
> check:
> 
> if ((u64)optlen < (u64)tmp.size + sizeof(tmp))
>         return -EINVAL;

Thanks for this fix.

> Fixes: 0c83842df40f ("netfilter: validate user input for expected length")
> Reported-by: syzbot <syzkaller@...glegroups.com>

Reviewed-by: Pablo Neira Ayuso <pablo@...filter.org>

> Signed-off-by: Eric Dumazet <edumazet@...gle.com>
> ---
>  net/ipv4/netfilter/arp_tables.c | 4 ++++
>  net/ipv4/netfilter/ip_tables.c  | 4 ++++
>  net/ipv6/netfilter/ip6_tables.c | 4 ++++
>  3 files changed, 12 insertions(+)
> 
> diff --git a/net/ipv4/netfilter/arp_tables.c b/net/ipv4/netfilter/arp_tables.c
> index b150c9929b12e86219a55c77da480e0c538b3449..14365b20f1c5c09964dd7024060116737f22cb63 100644
> --- a/net/ipv4/netfilter/arp_tables.c
> +++ b/net/ipv4/netfilter/arp_tables.c
> @@ -966,6 +966,8 @@ static int do_replace(struct net *net, sockptr_t arg, unsigned int len)
>  		return -ENOMEM;
>  	if (tmp.num_counters == 0)
>  		return -EINVAL;
> +	if ((u64)len < (u64)tmp.size + sizeof(tmp))
> +		return -EINVAL;
>  
>  	tmp.name[sizeof(tmp.name)-1] = 0;
>  
> @@ -1266,6 +1268,8 @@ static int compat_do_replace(struct net *net, sockptr_t arg, unsigned int len)
>  		return -ENOMEM;
>  	if (tmp.num_counters == 0)
>  		return -EINVAL;
> +	if ((u64)len < (u64)tmp.size + sizeof(tmp))
> +		return -EINVAL;
>  
>  	tmp.name[sizeof(tmp.name)-1] = 0;
>  
> diff --git a/net/ipv4/netfilter/ip_tables.c b/net/ipv4/netfilter/ip_tables.c
> index 487670759578168c5ff53bce6642898fc41936b3..fe89a056eb06c43743b2d7449e59f4e9360ba223 100644
> --- a/net/ipv4/netfilter/ip_tables.c
> +++ b/net/ipv4/netfilter/ip_tables.c
> @@ -1118,6 +1118,8 @@ do_replace(struct net *net, sockptr_t arg, unsigned int len)
>  		return -ENOMEM;
>  	if (tmp.num_counters == 0)
>  		return -EINVAL;
> +	if ((u64)len < (u64)tmp.size + sizeof(tmp))
> +		return -EINVAL;
>  
>  	tmp.name[sizeof(tmp.name)-1] = 0;
>  
> @@ -1504,6 +1506,8 @@ compat_do_replace(struct net *net, sockptr_t arg, unsigned int len)
>  		return -ENOMEM;
>  	if (tmp.num_counters == 0)
>  		return -EINVAL;
> +	if ((u64)len < (u64)tmp.size + sizeof(tmp))
> +		return -EINVAL;
>  
>  	tmp.name[sizeof(tmp.name)-1] = 0;
>  
> diff --git a/net/ipv6/netfilter/ip6_tables.c b/net/ipv6/netfilter/ip6_tables.c
> index 636b360311c5365fba2330f6ca2f7f1b6dd1363e..131f7bb2110d3a08244c6da40ff9be45a2be711b 100644
> --- a/net/ipv6/netfilter/ip6_tables.c
> +++ b/net/ipv6/netfilter/ip6_tables.c
> @@ -1135,6 +1135,8 @@ do_replace(struct net *net, sockptr_t arg, unsigned int len)
>  		return -ENOMEM;
>  	if (tmp.num_counters == 0)
>  		return -EINVAL;
> +	if ((u64)len < (u64)tmp.size + sizeof(tmp))
> +		return -EINVAL;
>  
>  	tmp.name[sizeof(tmp.name)-1] = 0;
>  
> @@ -1513,6 +1515,8 @@ compat_do_replace(struct net *net, sockptr_t arg, unsigned int len)
>  		return -ENOMEM;
>  	if (tmp.num_counters == 0)
>  		return -EINVAL;
> +	if ((u64)len < (u64)tmp.size + sizeof(tmp))
> +		return -EINVAL;
>  
>  	tmp.name[sizeof(tmp.name)-1] = 0;
>  
> -- 
> 2.44.0.478.gd926399ef9-goog
>