Re: [PATCH] SMACK netfilter smacklabel socket match

Paul Moore
2009-02-17T23:52:35Z

On Tuesday 17 February 2009 03:01:15 pm etienne wrote:
> I realize this patch is a little ugly, a cleaner way would be to insert
> struct smk_netlbladdr sorted from longest to smallest mask and break the
> loop as soon as we have a match... regards,

Agreed, the address matching code really should be improved; if you feel like
you could contribute the changes I'm pretty sure Casey would welcome the
patches :)

Regarding your fix below, I think a cleaner solution would be to do something
like the following in place of the existing mask check ...

if ((miap->s_addr & bestmask.s_addr) || (bestmask.s_addr == 0)) {
bestmask.s_addr = miap->s_addr;
bestlabel = snp->smk_label;
}

... however there is one small problem with this approach (your proposal
suffers from the same issue): normally the smack_host_label() code prefers the
first matching entry in the list, the change above preserves that with the
exception of a 0.0.0.0/0 entry. Granted, you shouldn't allow that in the
first place but I believe it is possible so it is something that needs to be
taken into consideration.

> Signed-off-by: Etienne <etienne.basset@numericable.fr>
> ------
> diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
> index 0278bc0..9d2576d 100644
> --- a/security/smack/smack_lsm.c
> +++ b/security/smack/smack_lsm.c
> @@ -1540,7 +1540,7 @@ static char *smack_host_label(struct sockaddr_in
> *sip) * If the list entry mask is less specific than the best * already
> found this entry is uninteresting.
> */
> - if ((miap->s_addr | bestmask.s_addr) == bestmask.s_addr)
> + if ( ((miap->s_addr | bestmask.s_addr) == bestmask.s_addr)
> && (miap->s_addr | bestmask.s_addr) != 0 ) continue;
> /*
> * This is better than any entry found so far.
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--
paul moore
linux @ hp