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, 6 insertions, 0 deletions

diff --git a/security/capability.c b/security/capability.c
index ec05730..1b943f5 100644
--- a/security/capability.c
+++ b/security/capability.c
@@ -396,6 +396,11 @@ static int cap_kernel_create_files_as(struct cred *new, struct inode *inode)
 	return 0;
 }
 
+static int cap_kernel_module_request(void)
+{
+	return 0;
+}
+
 static int cap_task_setuid(uid_t id0, uid_t id1, uid_t id2, int flags)
 {
 	return 0;
@@ -945,6 +950,7 @@ void security_fixup_ops(struct security_operations *ops)
 	set_to_cap_if_null(ops, cred_commit);
 	set_to_cap_if_null(ops, kernel_act_as);
 	set_to_cap_if_null(ops, kernel_create_files_as);
+	set_to_cap_if_null(ops, kernel_module_request);
 	set_to_cap_if_null(ops, task_setuid);
 	set_to_cap_if_null(ops, task_fix_setuid);
 	set_to_cap_if_null(ops, task_setgid);