linux-hardening - Re: [PATCH] netfilter: ipset: Replace strlcpy with strscpy

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Message-ID: <b7f91b9f-84d9-8eb9-246f-68b4cb3721f9@netfilter.org>
Date:   Fri, 16 Jun 2023 12:51:16 +0200 (CEST)
From:   Jozsef Kadlecsik <kadlec@...filter.org>
To:     Azeem Shaikh <azeemshaikh38@...il.com>
cc:     Pablo Neira Ayuso <pablo@...filter.org>,
        Florian Westphal <fw@...len.de>,
        linux-hardening@...r.kernel.org, netfilter-devel@...r.kernel.org,
        coreteam@...filter.org, linux-kernel@...r.kernel.org,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>, netdev@...r.kernel.org
Subject: Re: [PATCH] netfilter: ipset: Replace strlcpy with strscpy

On Tue, 13 Jun 2023, Azeem Shaikh wrote:

> strlcpy() reads the entire source buffer first.
> This read may exceed the destination size limit.
> This is both inefficient and can lead to linear read
> overflows if a source string is not NUL-terminated [1].
> In an effort to remove strlcpy() completely [2], replace
> strlcpy() here with strscpy().
> 
> Direct replacement is safe here since return value from all
> callers of STRLCPY macro were ignored.
> 
> [1] https://www.kernel.org/doc/html/latest/process/deprecated.html#strlcpy
> [2] https://github.com/KSPP/linux/issues/89
> 
> Signed-off-by: Azeem Shaikh <azeemshaikh38@...il.com>

Acked-by: Jozsef Kadlecsik <kadlec@...filter.org>

Best regards,
Jozsef

> ---
>  net/netfilter/ipset/ip_set_hash_netiface.c |   10 +++++-----
>  1 file changed, 5 insertions(+), 5 deletions(-)
> 
> diff --git a/net/netfilter/ipset/ip_set_hash_netiface.c b/net/netfilter/ipset/ip_set_hash_netiface.c
> index 031073286236..95aeb31c60e0 100644
> --- a/net/netfilter/ipset/ip_set_hash_netiface.c
> +++ b/net/netfilter/ipset/ip_set_hash_netiface.c
> @@ -40,7 +40,7 @@ MODULE_ALIAS("ip_set_hash:net,iface");
>  #define IP_SET_HASH_WITH_MULTI
>  #define IP_SET_HASH_WITH_NET0
>  
> -#define STRLCPY(a, b)	strlcpy(a, b, IFNAMSIZ)
> +#define STRSCPY(a, b)	strscpy(a, b, IFNAMSIZ)
>  
>  /* IPv4 variant */
>  
> @@ -182,11 +182,11 @@ hash_netiface4_kadt(struct ip_set *set, const struct sk_buff *skb,
>  
>  		if (!eiface)
>  			return -EINVAL;
> -		STRLCPY(e.iface, eiface);
> +		STRSCPY(e.iface, eiface);
>  		e.physdev = 1;
>  #endif
>  	} else {
> -		STRLCPY(e.iface, SRCDIR ? IFACE(in) : IFACE(out));
> +		STRSCPY(e.iface, SRCDIR ? IFACE(in) : IFACE(out));
>  	}
>  
>  	if (strlen(e.iface) == 0)
> @@ -400,11 +400,11 @@ hash_netiface6_kadt(struct ip_set *set, const struct sk_buff *skb,
>  
>  		if (!eiface)
>  			return -EINVAL;
> -		STRLCPY(e.iface, eiface);
> +		STRSCPY(e.iface, eiface);
>  		e.physdev = 1;
>  #endif
>  	} else {
> -		STRLCPY(e.iface, SRCDIR ? IFACE(in) : IFACE(out));
> +		STRSCPY(e.iface, SRCDIR ? IFACE(in) : IFACE(out));
>  	}
>  
>  	if (strlen(e.iface) == 0)
> -- 
> 2.41.0.162.gfafddb0af9-goog
> 
> 
> 

-
E-mail  : kadlec@...ckhole.kfki.hu, kadlecsik.jozsef@...ner.hu
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Address : Wigner Research Centre for Physics
          H-1525 Budapest 114, POB. 49, Hungary