Re: [PATCH] audit: Use struct net not pid_t to remember the network namespce to reply in

[Richard Guy Briggs]

On 14/03/16, Richard Guy Briggs wrote:
> On 14/02/28, Eric W. Biederman wrote:
> > 
> > While reading through 3.14-rc1 I found a pretty siginficant mishandling
> > of network namespaces in the recent audit changes.
> > 
> > In struct audit_netlink_list and audit_reply add a reference to the
> > network namespace of the caller and remove the userspace pid of the
> > caller.  This cleanly remembers the callers network namespace, and
> > removes a huge class of races and nasty failure modes that can occur
> > when attempting to relook up the callers network namespace from a pid_t
> > (including the caller's network namespace changing, pid wraparound, and
> > the pid simply not being present).
> > 
> > Signed-off-by: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>
> 
> Signed-off-by: Richard Guy Briggs <rgb@xxxxxxxxxxxx>

Sorry for the noise, please change that sig to:

Signed-off-by: Richard Guy Briggs <rgb@xxxxxxxxxx>

> > ---
> >  kernel/audit.c       |   10 ++++++----
> >  kernel/audit.h       |    2 +-
> >  kernel/auditfilter.c |    3 ++-
> >  3 files changed, 9 insertions(+), 6 deletions(-)
> > 
> > diff --git a/kernel/audit.c b/kernel/audit.c
> > index 34c5a2310fbf..1e5756f16f6f 100644
> > --- a/kernel/audit.c
> > +++ b/kernel/audit.c
> > @@ -182,7 +182,7 @@ struct audit_buffer {
> >  
> >  struct audit_reply {
> >  	__u32 portid;
> > -	pid_t pid;
> > +	struct net *net;	
> >  	struct sk_buff *skb;
> >  };
> >  
> > @@ -500,7 +500,7 @@ int audit_send_list(void *_dest)
> >  {
> >  	struct audit_netlink_list *dest = _dest;
> >  	struct sk_buff *skb;
> > -	struct net *net = get_net_ns_by_pid(dest->pid);
> > +	struct net *net = dest->net;
> >  	struct audit_net *aunet = net_generic(net, audit_net_id);
> >  
> >  	/* wait for parent to finish and send an ACK */
> > @@ -510,6 +510,7 @@ int audit_send_list(void *_dest)
> >  	while ((skb = __skb_dequeue(&dest->q)) != NULL)
> >  		netlink_unicast(aunet->nlsk, skb, dest->portid, 0);
> >  
> > +	put_net(net);
> >  	kfree(dest);
> >  
> >  	return 0;
> > @@ -543,7 +544,7 @@ out_kfree_skb:
> >  static int audit_send_reply_thread(void *arg)
> >  {
> >  	struct audit_reply *reply = (struct audit_reply *)arg;
> > -	struct net *net = get_net_ns_by_pid(reply->pid);
> > +	struct net *net = reply->net;
> >  	struct audit_net *aunet = net_generic(net, audit_net_id);
> >  
> >  	mutex_lock(&audit_cmd_mutex);
> > @@ -552,6 +553,7 @@ static int audit_send_reply_thread(void *arg)
> >  	/* Ignore failure. It'll only happen if the sender goes away,
> >  	   because our timeout is set to infinite. */
> >  	netlink_unicast(aunet->nlsk , reply->skb, reply->portid, 0);
> > +	put_net(net);
> >  	kfree(reply);
> >  	return 0;
> >  }
> > @@ -583,8 +585,8 @@ static void audit_send_reply(__u32 portid, int seq, int type, int done,
> >  	if (!skb)
> >  		goto out;
> >  
> > +	reply->net = get_net(current->nsproxy->net_ns);
> >  	reply->portid = portid;
> > -	reply->pid = task_pid_vnr(current);
> >  	reply->skb = skb;
> >  
> >  	tsk = kthread_run(audit_send_reply_thread, reply, "audit_send_reply");
> > diff --git a/kernel/audit.h b/kernel/audit.h
> > index 57cc64d67718..8df132214606 100644
> > --- a/kernel/audit.h
> > +++ b/kernel/audit.h
> > @@ -247,7 +247,7 @@ extern void		    audit_panic(const char *message);
> >  
> >  struct audit_netlink_list {
> >  	__u32 portid;
> > -	pid_t pid;
> > +	struct net *net;
> >  	struct sk_buff_head q;
> >  };
> >  
> > diff --git a/kernel/auditfilter.c b/kernel/auditfilter.c
> > index 14a78cca384e..a5e3d73d73e4 100644
> > --- a/kernel/auditfilter.c
> > +++ b/kernel/auditfilter.c
> > @@ -29,6 +29,7 @@
> >  #include <linux/sched.h>
> >  #include <linux/slab.h>
> >  #include <linux/security.h>
> > +#include <net/net_namespace.h>
> >  #include "audit.h"
> >  
> >  /*
> > @@ -1083,8 +1084,8 @@ int audit_list_rules_send(__u32 portid, int seq)
> >  	dest = kmalloc(sizeof(struct audit_netlink_list), GFP_KERNEL);
> >  	if (!dest)
> >  		return -ENOMEM;
> > +	dest->net = get_net(current->nsproxy->net_ns);
> >  	dest->portid = portid;
> > -	dest->pid = task_pid_vnr(current);
> >  	skb_queue_head_init(&dest->q);
> >  
> >  	mutex_lock(&audit_filter_mutex);
> > -- 
> > 1.7.5.4
> > 
> 
> - RGB
> 
> --
> Richard Guy Briggs <rbriggs@xxxxxxxxxx>
> Senior Software Engineer, Kernel Security, AMER ENG Base Operating Systems, Red Hat
> Remote, Ottawa, Canada
> Voice: +1.647.777.2635, Internal: (81) 32635, Alt: +1.613.693.0684x3545

- RGB

--
Richard Guy Briggs <rbriggs@xxxxxxxxxx>
Senior Software Engineer, Kernel Security, AMER ENG Base Operating Systems, Red Hat
Remote, Ottawa, Canada
Voice: +1.647.777.2635, Internal: (81) 32635, Alt: +1.613.693.0684x3545
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