security: introducing security_request_module

Calling request_module() will trigger a userspace upcall which will load a
new module into the kernel.  This can be a dangerous event if the process
able to trigger request_module() is able to control either the modprobe
binary or the module binary.  This patch adds a new security hook to
request_module() which can be used by an LSM to control a processes ability
to call request_module().

Signed-off-by: Eric Paris <eparis@redhat.com>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Signed-off-by: James Morris <jmorris@namei.org>

1 files changed, 4 insertions, 0 deletions

diff --git a/kernel/kmod.c b/kernel/kmod.c
index 385c31a1bdbf..5a7ae57f983f 100644
--- a/kernel/kmod.c
+++ b/kernel/kmod.c
@@ -78,6 +78,10 @@ int __request_module(bool wait, const char *fmt, ...)
 #define MAX_KMOD_CONCURRENT 50  /* Completely arbitrary value - KAO */
         static int kmod_loop_msg;
 
+        ret = security_kernel_module_request();
+        if (ret)
+                return ret;
+
         va_start(args, fmt);
         ret = vsnprintf(module_name, MODULE_NAME_LEN, fmt, args);
         va_end(args);