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

Discussion:

Eric W. Biederman

2014-02-28 18:49:05 UTC

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" <***@xmission.com>
---
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

Richard Guy Briggs

2014-03-01 01:11:42 UTC