Re: [PATCH v2 1/2] netfilter_queue: enable UID/GID socket info retrieval

[Pablo Neira Ayuso <pablo@netfilter.org>]

On Fri, Dec 20, 2013 at 10:26:38AM +0100, Pablo Neira Ayuso wrote:
> Hi,
> 
> On Thu, Dec 19, 2013 at 12:03:26PM +0100, valentina.giusti@bmw-carit.de wrote:
> > From: Valentina Giusti <valentina.giusti@oss.bmw-carit.de>
> > 
> > Thanks to commits 41063e9 (ipv4: Early TCP socket demux) and 421b388 (udp: ipv4:
> > Add udp early demux) it is now possible to parse UID and GID socket info
> > also for incoming TCP and UDP connections. Having this info available, it
> > is convenient to let NFQUEUE parse it in order to improve and refine the
> > traffic analysis in userspace.
> > 
> > Signed-off-by: Valentina Giusti <valentina.giusti@bmw-carit.de>
> > ---
> >  include/uapi/linux/netfilter/nfnetlink_queue.h |  5 ++++-
> >  net/netfilter/nfnetlink_queue_core.c           | 31 ++++++++++++++++++++++++++
> >  2 files changed, 35 insertions(+), 1 deletion(-)
> > 
> > diff --git a/include/uapi/linux/netfilter/nfnetlink_queue.h b/include/uapi/linux/netfilter/nfnetlink_queue.h
> > index 0132bad..8dd819e 100644
> > --- a/include/uapi/linux/netfilter/nfnetlink_queue.h
> > +++ b/include/uapi/linux/netfilter/nfnetlink_queue.h
> > @@ -47,6 +47,8 @@ enum nfqnl_attr_type {
> >  	NFQA_CAP_LEN,			/* __u32 length of captured packet */
> >  	NFQA_SKB_INFO,			/* __u32 skb meta information */
> >  	NFQA_EXP,			/* nf_conntrack_netlink.h */
> > +	NFQA_UID,			/* __u32 sk uid */
> > +	NFQA_GID,			/* __u32 sk gid */
> >  
> >  	__NFQA_MAX
> >  };
> > @@ -99,7 +101,8 @@ enum nfqnl_attr_config {
> >  #define NFQA_CFG_F_FAIL_OPEN			(1 << 0)
> >  #define NFQA_CFG_F_CONNTRACK			(1 << 1)
> >  #define NFQA_CFG_F_GSO				(1 << 2)
> > -#define NFQA_CFG_F_MAX				(1 << 3)
> > +#define NFQA_CFG_F_UID_GID			(1 << 3)
> > +#define NFQA_CFG_F_MAX				(1 << 4)
> >  
> >  /* flags for NFQA_SKB_INFO */
> >  /* packet appears to have wrong checksums, but they are ok */
> > diff --git a/net/netfilter/nfnetlink_queue_core.c b/net/netfilter/nfnetlink_queue_core.c
> > index 21258cf..2cdef07 100644
> > --- a/net/netfilter/nfnetlink_queue_core.c
> > +++ b/net/netfilter/nfnetlink_queue_core.c
> > @@ -297,6 +297,29 @@ nfqnl_put_packet_info(struct sk_buff *nlskb, struct sk_buff *packet,
> >  	return flags ? nla_put_be32(nlskb, NFQA_SKB_INFO, htonl(flags)) : 0;
> >  }
> >  
> > +static int nfqnl_put_sk_uidgid(struct sk_buff *skb, struct sock *sk)
> > +{
> > +	const struct cred *cred;
> > +
> > +	if (sk && sk->sk_state != TCP_TIME_WAIT) {
> > +		read_lock_bh(&sk->sk_callback_lock);
> > +		if (sk->sk_socket && sk->sk_socket->file) {
> > +			cred = sk->sk_socket->file->f_cred;
> > +			if (nla_put_u32(skb, NFQA_UID, htonl(cred->fsuid)))
> 
> I'm hitting this compilation error here:
> 
> net/netfilter/nfnetlink_queue_core.c: In function ‘nfqnl_put_sk_uidgid’:
> net/netfilter/nfnetlink_queue_core.c:308:4: error: aggregate value used where an integer was expected
> 
> It seems that in recent kernels you have to use:
> 
>         from_kuid_munged(&init_user_ns, cred->fsuid);
> 
> to retrieve the integer that represents the uid.
> 
> Please, 

sorry, I left this sentence incomplete, I was telling... Please, test
your patches with current git trees :-). Thanks.