Subject: Re: [PATCH 2/5] Export the raw sock's security context to proc.

From: Stephen Smalley <[email-masked]>
Date: Fri, 05 Aug 2011 09:51:07 -0400

On Fri, 2011-08-05 at 16:58 +0800, [email-masked] wrote:
> From: Roy.Li <[email-masked]>
> 
> The element sk_security of struct sock represents the socket
> security context ID, which is inheriting from the process when
> creates this socket on most of the time.
> 
> but when SELinux type_transition rule is applied to socket, or
> application sets /proc/xxx/attr/createsock, the socket security
> context would be different from the creating process. on this
> condition, the "netstat -Z" will return wrong value, since
> "netstat -Z" only returns the process security context as socket
> process security.
> 
> Export the raw sock's security context to proc, so that "netstat -Z"
> could be fixed by reading procfs.
> 
> Signed-off-by: Roy.Li <[email-masked]>
> ---
>  net/ipv4/raw.c |    9 +++++++--
>  1 files changed, 7 insertions(+), 2 deletions(-)
> 
> diff --git a/net/ipv4/raw.c b/net/ipv4/raw.c
> index 1457acb..645d373 100644
> --- a/net/ipv4/raw.c
> +++ b/net/ipv4/raw.c
> @@ -972,6 +972,7 @@ EXPORT_SYMBOL_GPL(raw_seq_stop);
>  
>  static void raw_sock_seq_show(struct seq_file *seq, struct sock *sp, int i)
>  {
> +	int sclen;
>  	struct inet_sock *inet = inet_sk(sp);
>  	__be32 dest = inet->inet_daddr,
>  	       src = inet->inet_rcv_saddr;
> @@ -979,12 +980,15 @@ static void raw_sock_seq_show(struct seq_file *seq, struct sock *sp, int i)
>  	      srcp  = inet->inet_num;
>  
>  	seq_printf(seq, "%4d: %08X:%04X %08X:%04X"
> -		" %02X %08X:%08X %02X:%08lX %08X %5d %8d %lu %d %pK %d\n",
> +		" %02X %08X:%08X %02X:%08lX %08X %5d %8d %lu %d %pK %d",
>  		i, src, srcp, dest, destp, sp->sk_state,
>  		sk_wmem_alloc_get(sp),
>  		sk_rmem_alloc_get(sp),
>  		0, 0L, 0, sock_i_uid(sp), 0, sock_i_ino(sp),
>  		atomic_read(&sp->sk_refcnt), sp, atomic_read(&sp->sk_drops));
> +
> +	sock_write_secctx(sp, seq, &sclen);

You don't seem to use the return value or the sclen.  If that's
intentional, then why does sclen exist and why isn't the function void?

> +	seq_putc(seq, '\n');
>  }
>  
>  static int raw_seq_show(struct seq_file *seq, void *v)
> @@ -992,7 +996,8 @@ static int raw_seq_show(struct seq_file *seq, void *v)
>  	if (v == SEQ_START_TOKEN)
>  		seq_printf(seq, "  sl  local_address rem_address   st tx_queue "
>  				"rx_queue tr tm->when retrnsmt   uid  timeout "
> -				"inode ref pointer drops\n");
> +				"inode ref pointer drops %s",
> +				(selinux_is_enabled() ? "  scontext\n" : "\n"));

The rest of your code isn't SELinux-specific and should work for other
security modules, so there is no reason to make this SELinux-specific
either.  The audit system may provide a useful example.  I'd just always
include the field header (otherwise how can we add any further fields
unambiguously?), and make it something more general, like "seclabel".

>  	else
>  		raw_sock_seq_show(seq, v, raw_seq_private(seq)->bucket);
>  	return 0;

-- 
Stephen Smalley
National Security Agency