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

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Message-ID: <8e0fd132-4574-4ae7-45ea-88c4a2ec94b2@gmail.com>
Date:   Tue, 7 Jan 2020 11:44:34 -0700
From:   David Ahern <dsahern@...il.com>
To:     Casey Schaufler <casey@...aufler-ca.com>,
        Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>
Cc:     "netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: Re: commit b9ef5513c99b breaks ping to ipv6 linklocal addresses on
 debian buster

On 1/7/20 11:40 AM, Casey Schaufler wrote:
> Does this patch address the Debian issue? It works for the test program
> and on my Fedora system.
> 
> 
>  security/smack/smack_lsm.c | 9 ++++++---
>  1 file changed, 6 insertions(+), 3 deletions(-)
> 
> diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
> index 50c536cad85b..b0bb36419aeb 100644
> --- a/security/smack/smack_lsm.c
> +++ b/security/smack/smack_lsm.c
> @@ -2857,7 +2857,9 @@ 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 0;
> +		if (sap->sa_family != AF_INET6)
>  			return -EINVAL;

I doubt it; can't test it until tonight. strace for ping on buster is
showing this:

$ strace -e connect ping6 -c1 -w1 ff02::1%eth1
connect(4, {sa_family=AF_UNSPEC,
sa_data="\4\1\0\0\0\0\377\2\0\0\0\0\0\0\0\0\0\0\0\0\0\1\3\0\0\0"}, 28)

ie., the addrlen >= SIN6_LEN_RFC2133 but the family is AF_UNSPEC. That
suggests to me the first check passes and the second check fails.