[PATCH] audit: listen in all network namespaces

From: Richard Guy Briggs
Date: Tue Jul 16 2013 - 16:15:50 EST


Convert audit from only listening in init_net to use register_pernet_subsys()
to dynamically manage the netlink socket list.

Signed-off-by: Richard Guy Briggs <rgb@xxxxxxxxxx>
---
kernel/audit.c | 64 ++++++++++++++++++++++++++++++++++++++++++++++---------
kernel/audit.h | 4 +++
2 files changed, 57 insertions(+), 11 deletions(-)

diff --git a/kernel/audit.c b/kernel/audit.c
index 91e53d0..06e2676 100644
--- a/kernel/audit.c
+++ b/kernel/audit.c
@@ -64,6 +64,7 @@
#include <linux/freezer.h>
#include <linux/tty.h>
#include <linux/pid_namespace.h>
+#include <net/netns/generic.h>

#include "audit.h"

@@ -122,6 +123,7 @@ static atomic_t audit_lost = ATOMIC_INIT(0);

/* The netlink socket. */
static struct sock *audit_sock;
+int audit_net_id;

/* Hash for inode-based rules */
struct list_head audit_inode_hash[AUDIT_INODE_BUCKETS];
@@ -391,6 +393,7 @@ static void kauditd_send_skb(struct sk_buff *skb)
printk(KERN_ERR "audit: *NO* daemon at audit_pid=%d\n", audit_pid);
audit_log_lost("auditd disappeared\n");
audit_pid = 0;
+ audit_sock = NULL;
/* we might get lucky and get this in the next auditd */
audit_hold_skb(skb);
} else
@@ -474,13 +477,15 @@ int audit_send_list(void *_dest)
struct audit_netlink_list *dest = _dest;
int pid = dest->pid;
struct sk_buff *skb;
+ struct net *net = get_net_ns_by_pid(pid);
+ struct audit_net *aunet = net_generic(net, audit_net_id);

/* wait for parent to finish and send an ACK */
mutex_lock(&audit_cmd_mutex);
mutex_unlock(&audit_cmd_mutex);

while ((skb = __skb_dequeue(&dest->q)) != NULL)
- netlink_unicast(audit_sock, skb, pid, 0);
+ netlink_unicast(aunet->nlsk, skb, pid, 0);

kfree(dest);

@@ -515,13 +520,15 @@ 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 audit_net *aunet = net_generic(net, audit_net_id);

mutex_lock(&audit_cmd_mutex);
mutex_unlock(&audit_cmd_mutex);

/* Ignore failure. It'll only happen if the sender goes away,
because our timeout is set to infinite. */
- netlink_unicast(audit_sock, reply->skb, reply->pid, 0);
+ netlink_unicast(aunet->nlsk , reply->skb, reply->pid, 0);
kfree(reply);
return 0;
}
@@ -690,6 +697,7 @@ static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
audit_log_config_change("audit_pid", new_pid, audit_pid, 1);
audit_pid = new_pid;
audit_nlk_portid = NETLINK_CB(skb).portid;
+ audit_sock = NETLINK_CB(skb).sk;
}
if (status_get->mask & AUDIT_STATUS_RATE_LIMIT) {
err = audit_set_rate_limit(status_get->rate_limit);
@@ -886,24 +894,58 @@ static void audit_receive(struct sk_buff *skb)
mutex_unlock(&audit_cmd_mutex);
}

-/* Initialize audit support at boot time. */
-static int __init audit_init(void)
+static int __net_init audit_net_init(struct net *net)
{
- int i;
struct netlink_kernel_cfg cfg = {
.input = audit_receive,
};

+ struct audit_net *aunet = net_generic(net, audit_net_id);
+
+ pr_info("audit: initializing netlink socket in namespace\n");
+
+ aunet->nlsk = netlink_kernel_create(net, NETLINK_AUDIT, &cfg);
+ if (aunet->nlsk == NULL)
+ return -ENOMEM;
+ if (!aunet->nlsk)
+ audit_panic("cannot initialize netlink socket in namespace");
+ else
+ aunet->nlsk->sk_sndtimeo = MAX_SCHEDULE_TIMEOUT;
+ return 0;
+}
+
+static void __net_exit audit_net_exit(struct net *net)
+{
+ struct audit_net *aunet = net_generic(net, audit_net_id);
+ struct sock *sock = aunet->nlsk;
+ if (sock == audit_sock) {
+ audit_pid = 0;
+ audit_sock = NULL;
+ }
+
+ rcu_assign_pointer(aunet->nlsk, NULL);
+ synchronize_net();
+ netlink_kernel_release(sock);
+}
+
+static struct pernet_operations __net_initdata audit_net_ops = {
+ .init = audit_net_init,
+ .exit = audit_net_exit,
+ .id = &audit_net_id,
+ .size = sizeof(struct audit_net),
+};
+
+/* Initialize audit support at boot time. */
+static int __init audit_init(void)
+{
+ int i;
+
if (audit_initialized == AUDIT_DISABLED)
return 0;

- printk(KERN_INFO "audit: initializing netlink socket (%s)\n",
+ pr_info("audit: initializing netlink subsys (%s)\n",
audit_default ? "enabled" : "disabled");
- audit_sock = netlink_kernel_create(&init_net, NETLINK_AUDIT, &cfg);
- if (!audit_sock)
- audit_panic("cannot initialize netlink socket");
- else
- audit_sock->sk_sndtimeo = MAX_SCHEDULE_TIMEOUT;
+ register_pernet_subsys(&audit_net_ops);

skb_queue_head_init(&audit_skb_queue);
skb_queue_head_init(&audit_skb_hold_queue);
diff --git a/kernel/audit.h b/kernel/audit.h
index 123c9b7..b7cc537 100644
--- a/kernel/audit.h
+++ b/kernel/audit.h
@@ -249,6 +249,10 @@ struct audit_netlink_list {

int audit_send_list(void *);

+struct audit_net {
+ struct sock *nlsk;
+};
+
extern int selinux_audit_rule_update(void);

extern struct mutex audit_filter_mutex;
--
1.7.1

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