netdev - Re: commit b9ef5513c99b breaks ping to ipv6 linklocal addresses on debian buster

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Message-ID: <a2612f24-00b7-7e9e-5a9e-d0d82b22ea8e@i-love.sakura.ne.jp>
Date:   Mon, 6 Jan 2020 20:04:42 +0900
From:   Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>
To:     David Ahern <dsahern@...il.com>
Cc:     Casey Schaufler <casey@...aufler-ca.com>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: Re: commit b9ef5513c99b breaks ping to ipv6 linklocal addresses on
 debian buster

On 2020/01/06 13:20, David Ahern wrote:
> Hi:
> 
> The failure is the connect function, not the bind.

Oops, I missed it.

> 
> This change seems more appropriate to me (and fixes the failure):
> 
> diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
> index ecea41ce919b..ce5e3be7c111 100644
> --- a/security/smack/smack_lsm.c
> +++ b/security/smack/smack_lsm.c
> @@ -2854,7 +2854,7 @@ static int smack_socket_connect(struct socket
> *sock, struct sockaddr *sap,
>                 rc = smack_netlabel_send(sock->sk, (struct sockaddr_in
> *)sap);
>                 break;
>         case PF_INET6:
> -               if (addrlen < SIN6_LEN_RFC2133 || sap->sa_family !=
> AF_INET6)
> +               if (addrlen < SIN6_LEN_RFC2133)
>                         return -EINVAL;

This is called upon connect(), isn't it? Then, it is possible that a socket's
protocol family is PF_INET6 but address given is AF_INET, isn't it? For example,
__ip6_datagram_connect() checks for AF_INET before checking addrlen is at least
SIN6_LEN_RFC2133 bytes. Thus, I think that we need to return 0 if address given
is AF_INET even if socket is PF_INET6.

>  #ifdef SMACK_IPV6_SECMARK_LABELING
>                 rsp = smack_ipv6host_label(sip);
> 
> 
> ie., if the socket family is AF_INET6 the address length should be an
> IPv6 address. The family in the sockaddr is not as important.
> 

Commit b9ef5513c99b was wrong, but we need to also fix commit c673944347ed ?