audit: log module name on delete_module

When a sysadmin wishes to monitor module unloading with a syscall rule such as:
 -a always,exit -F arch=x86_64 -S delete_module -F key=mod-unload
the SYSCALL record doesn't tell us what module was requested for unloading.

Use the new KERN_MODULE auxiliary record to record it.
The SYSCALL record result code will list the return code.

See: https://github.com/linux-audit/audit-kernel/issues/37
    https://github.com/linux-audit/audit-kernel/issues/7
    https://github.com/linux-audit/audit-kernel/wiki/RFE-Module-Load-Record-FormatSigned-off-by: Richard Guy Briggs <rgb@redhat.com>
Acked-by: Jessica Yu <jeyu@redhat.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>

kernel/module.c

@@ -947,6 +947,8 @@ SYSCALL_DEFINE2(delete_module, const char __user *, name_user,
 		return -EFAULT;
 	name[MODULE_NAME_LEN-1] = '\0';
 
+	audit_log_kern_module(name);
+
 	if (mutex_lock_interruptible(&module_mutex) != 0)
 		return -EINTR;