[PATCH] Audit: make audit=0 actually turn off audit

Currently audit=0 on the kernel command line does absolutely nothing.
Audit always loads and always uses its resources such as creating the
kernel netlink socket.  This patch causes audit=0 to actually disable
audit.  Audit will use no resources and starting the userspace auditd
daemon will not cause the kernel audit system to activate.

Signed-off-by: Eric Paris <eparis@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 21 insertions, 7 deletions

diff --git a/kernel/audit.c b/kernel/audit.c
index 4414e93d8750..d8646c23b427 100644
--- a/kernel/audit.c
+++ b/kernel/audit.c
@@ -61,8 +61,11 @@
 
 #include "audit.h"
 
-/* No auditing will take place until audit_initialized != 0.
+/* No auditing will take place until audit_initialized == AUDIT_INITIALIZED.
  * (Initialization happens after skb_init is called.) */
+#define AUDIT_DISABLED          -1
+#define AUDIT_UNINITIALIZED     0
+#define AUDIT_INITIALIZED       1
 static int      audit_initialized;
 
 #define AUDIT_OFF       0
@@ -965,6 +968,9 @@ static int __init audit_init(void)
 {
         int i;
 
+        if (audit_initialized == AUDIT_DISABLED)
+                return 0;
+
         printk(KERN_INFO "audit: initializing netlink socket (%s)\n",
                audit_default ? "enabled" : "disabled");
         audit_sock = netlink_kernel_create(&init_net, NETLINK_AUDIT, 0,
@@ -976,7 +982,7 @@ static int __init audit_init(void)
 
         skb_queue_head_init(&audit_skb_queue);
         skb_queue_head_init(&audit_skb_hold_queue);
-        audit_initialized = 1;
+        audit_initialized = AUDIT_INITIALIZED;
         audit_enabled = audit_default;
         audit_ever_enabled |= !!audit_default;
 
@@ -999,13 +1005,21 @@ __initcall(audit_init);
 static int __init audit_enable(char *str)
 {
         audit_default = !!simple_strtol(str, NULL, 0);
-        printk(KERN_INFO "audit: %s%s\n",
-               audit_default ? "enabled" : "disabled",
-               audit_initialized ? "" : " (after initialization)");
-        if (audit_initialized) {
+        if (!audit_default)
+                audit_initialized = AUDIT_DISABLED;
+
+        printk(KERN_INFO "audit: %s", audit_default ? "enabled" : "disabled");
+
+        if (audit_initialized == AUDIT_INITIALIZED) {
                 audit_enabled = audit_default;
                 audit_ever_enabled |= !!audit_default;
+        } else if (audit_initialized == AUDIT_UNINITIALIZED) {
+                printk(" (after initialization)");
+        } else {
+                printk(" (until reboot)");
         }
+        printk("\n");
+
         return 1;
 }
 
@@ -1146,7 +1160,7 @@ struct audit_buffer *audit_log_start(struct audit_context *ctx, gfp_t gfp_mask,
         int reserve;
         unsigned long timeout_start = jiffies;
 
-        if (!audit_initialized)
+        if (audit_initialized != AUDIT_INITIALIZED)
                 return NULL;
 
         if (unlikely(audit_filter_type(type)))