netdev - Re: [PATCHv2 net] sctp: do not check port in sctp_inet6_cmp

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Date:   Thu, 12 Apr 2018 09:58:41 -0400
From:   Neil Horman <nhorman@...driver.com>
To:     Xin Long <lucien.xin@...il.com>
Cc:     network dev <netdev@...r.kernel.org>, linux-sctp@...r.kernel.org,
        davem@...emloft.net,
        Marcelo Ricardo Leitner <marcelo.leitner@...il.com>
Subject: Re: [PATCHv2 net] sctp: do not check port in sctp_inet6_cmp_addr

On Thu, Apr 12, 2018 at 02:24:31PM +0800, Xin Long wrote:
> pf->cmp_addr() is called before binding a v6 address to the sock. It
> should not check ports, like in sctp_inet_cmp_addr.
> 
> But sctp_inet6_cmp_addr checks the addr by invoking af(6)->cmp_addr,
> sctp_v6_cmp_addr where it also compares the ports.
> 
> This would cause that setsockopt(SCTP_SOCKOPT_BINDX_ADD) could bind
> multiple duplicated IPv6 addresses after Commit 40b4f0fd74e4 ("sctp:
> lack the check for ports in sctp_v6_cmp_addr").
> 
> This patch is to remove af->cmp_addr called in sctp_inet6_cmp_addr,
> but do the proper check for both v6 addrs and v4mapped addrs.
> 
> v1->v2:
>   - define __sctp_v6_cmp_addr to do the common address comparison
>     used for both pf and af v6 cmp_addr.
> 
> Fixes: 40b4f0fd74e4 ("sctp: lack the check for ports in sctp_v6_cmp_addr")
> Reported-by: Jianwen Ji <jiji@...hat.com>
> Signed-off-by: Xin Long <lucien.xin@...il.com>
> ---
>  net/sctp/ipv6.c | 60 ++++++++++++++++++++++++++++-----------------------------
>  1 file changed, 30 insertions(+), 30 deletions(-)
> 
> diff --git a/net/sctp/ipv6.c b/net/sctp/ipv6.c
> index f1fc48e..09aba03 100644
> --- a/net/sctp/ipv6.c
> +++ b/net/sctp/ipv6.c
> @@ -521,46 +521,49 @@ static void sctp_v6_to_addr(union sctp_addr *addr, struct in6_addr *saddr,
>  	addr->v6.sin6_scope_id = 0;
>  }
>  
> -/* Compare addresses exactly.
> - * v4-mapped-v6 is also in consideration.
> - */
> -static int sctp_v6_cmp_addr(const union sctp_addr *addr1,
> -			    const union sctp_addr *addr2)
> +static int __sctp_v6_cmp_addr(const union sctp_addr *addr1,
> +			      const union sctp_addr *addr2)
>  {
>  	if (addr1->sa.sa_family != addr2->sa.sa_family) {
>  		if (addr1->sa.sa_family == AF_INET &&
>  		    addr2->sa.sa_family == AF_INET6 &&
> -		    ipv6_addr_v4mapped(&addr2->v6.sin6_addr)) {
> -			if (addr2->v6.sin6_port == addr1->v4.sin_port &&
> -			    addr2->v6.sin6_addr.s6_addr32[3] ==
> -			    addr1->v4.sin_addr.s_addr)
> -				return 1;
> -		}
> +		    ipv6_addr_v4mapped(&addr2->v6.sin6_addr) &&
> +		    addr2->v6.sin6_addr.s6_addr32[3] ==
> +		    addr1->v4.sin_addr.s_addr)
> +			return 1;
> +
>  		if (addr2->sa.sa_family == AF_INET &&
>  		    addr1->sa.sa_family == AF_INET6 &&
> -		    ipv6_addr_v4mapped(&addr1->v6.sin6_addr)) {
> -			if (addr1->v6.sin6_port == addr2->v4.sin_port &&
> -			    addr1->v6.sin6_addr.s6_addr32[3] ==
> -			    addr2->v4.sin_addr.s_addr)
> -				return 1;
> -		}
> +		    ipv6_addr_v4mapped(&addr1->v6.sin6_addr) &&
> +		    addr1->v6.sin6_addr.s6_addr32[3] ==
> +		    addr2->v4.sin_addr.s_addr)
> +			return 1;
> +
>  		return 0;
>  	}
> -	if (addr1->v6.sin6_port != addr2->v6.sin6_port)
> -		return 0;
> +
>  	if (!ipv6_addr_equal(&addr1->v6.sin6_addr, &addr2->v6.sin6_addr))
>  		return 0;
> +
>  	/* If this is a linklocal address, compare the scope_id. */
> -	if (ipv6_addr_type(&addr1->v6.sin6_addr) & IPV6_ADDR_LINKLOCAL) {
> -		if (addr1->v6.sin6_scope_id && addr2->v6.sin6_scope_id &&
> -		    (addr1->v6.sin6_scope_id != addr2->v6.sin6_scope_id)) {
> -			return 0;
> -		}
> -	}
> +	if ((ipv6_addr_type(&addr1->v6.sin6_addr) & IPV6_ADDR_LINKLOCAL) &&
> +	    addr1->v6.sin6_scope_id && addr2->v6.sin6_scope_id &&
> +	    addr1->v6.sin6_scope_id != addr2->v6.sin6_scope_id)
> +		return 0;
>  
>  	return 1;
>  }
>  
> +/* Compare addresses exactly.
> + * v4-mapped-v6 is also in consideration.
> + */
> +static int sctp_v6_cmp_addr(const union sctp_addr *addr1,
> +			    const union sctp_addr *addr2)
> +{
> +	return __sctp_v6_cmp_addr(addr1, addr2) &&
> +	       addr1->v6.sin6_port == addr2->v6.sin6_port;
> +}
> +
>  /* Initialize addr struct to INADDR_ANY. */
>  static void sctp_v6_inaddr_any(union sctp_addr *addr, __be16 port)
>  {
> @@ -846,8 +849,8 @@ static int sctp_inet6_cmp_addr(const union sctp_addr *addr1,
>  			       const union sctp_addr *addr2,
>  			       struct sctp_sock *opt)
>  {
> -	struct sctp_af *af1, *af2;
>  	struct sock *sk = sctp_opt2sk(opt);
> +	struct sctp_af *af1, *af2;
>  
>  	af1 = sctp_get_af_specific(addr1->sa.sa_family);
>  	af2 = sctp_get_af_specific(addr2->sa.sa_family);
> @@ -863,10 +866,7 @@ static int sctp_inet6_cmp_addr(const union sctp_addr *addr1,
>  	if (sctp_is_any(sk, addr1) || sctp_is_any(sk, addr2))
>  		return 1;
>  
> -	if (addr1->sa.sa_family != addr2->sa.sa_family)
> -		return 0;
> -
> -	return af1->cmp_addr(addr1, addr2);
> +	return __sctp_v6_cmp_addr(addr1, addr2);
>  }
>  
>  /* Verify that the provided sockaddr looks bindable.   Common verification,
> -- 
> 2.1.0
> 
> --
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> 
Acked-by: Neil Horman <nhorman@...driver.com>