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audit: Use struct net not pid_t to remember the network namespce to reply in 

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@xmission.com>
Acked-by: Richard Guy Briggs <rgb@redhat.com>
Signed-off-by: Eric Paris <eparis@redhat.com>
This commit is contained in:
Eric W. Biederman 2014-02-28 10:49:05 -08:00 committed by Eric Paris
parent 3f1c82502c
commit 638a0fd2a0
3 changed files with 9 additions and 6 deletions
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10
kernel/audit.c
View File

@ -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");

2
kernel/audit.h
View File

@ -253,7 +253,7 @@ extern void audit_panic(const char *message);
struct audit_netlink_list {
__u32 portid;
pid_t pid;
struct net *net;
struct sk_buff_head q;
};

3
kernel/auditfilter.c
View File

@ -31,6 +31,7 @@
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/security.h>
#include <net/net_namespace.h>
#include "audit.h"
/*
@ -1085,8 +1086,8 @@ 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);