LSM: Identify modules by more than name

Create a struct lsm_id to contain identifying information about Linux
Security Modules (LSMs). At inception this contains the name of the
module and an identifier associated with the security module.  Change
the security_add_hooks() interface to use this structure.  Change the
individual modules to maintain their own struct lsm_id and pass it to
security_add_hooks().

The values are for LSM identifiers are defined in a new UAPI
header file linux/lsm.h. Each existing LSM has been updated to
include it's LSMID in the lsm_id.

The LSM ID values are sequential, with the oldest module
LSM_ID_CAPABILITY being the lowest value and the existing modules
numbered in the order they were included in the main line kernel.
This is an arbitrary convention for assigning the values, but
none better presents itself. The value 0 is defined as being invalid.
The values 1-99 are reserved for any special case uses which may
arise in the future. This may include attributes of the LSM
infrastructure itself, possibly related to namespacing or network
attribute management. A special range is identified for such attributes
to help reduce confusion for developers unfamiliar with LSMs.

LSM attribute values are defined for the attributes presented by
modules that are available today. As with the LSM IDs, The value 0
is defined as being invalid. The values 1-99 are reserved for any
special case uses which may arise in the future.

Cc: linux-security-module <linux-security-module@vger.kernel.org>
Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Serge Hallyn <serge@hallyn.com>
Reviewed-by: Mickael Salaun <mic@digikod.net>
Reviewed-by: John Johansen <john.johansen@canonical.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Nacked-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
[PM: forward ported beyond v6.6 due merge window changes]
Signed-off-by: Paul Moore <paul@paul-moore.com>

1 files changed, 8 insertions, 1 deletions

diff --git a/security/bpf/hooks.c b/security/bpf/hooks.c
index cfaf1d0e6a5f..91011e0c361a 100644
--- a/security/bpf/hooks.c
+++ b/security/bpf/hooks.c
@@ -5,6 +5,7 @@
  */
 #include <linux/lsm_hooks.h>
 #include <linux/bpf_lsm.h>
+#include <uapi/linux/lsm.h>
 
 static struct security_hook_list bpf_lsm_hooks[] __ro_after_init = {
 	#define LSM_HOOK(RET, DEFAULT, NAME, ...) \
@@ -15,9 +16,15 @@ static struct security_hook_list bpf_lsm_hooks[] __ro_after_init = {
 	LSM_HOOK_INIT(task_free, bpf_task_storage_free),
 };
 
+const struct lsm_id bpf_lsmid = {
+	.name = "bpf",
+	.id = LSM_ID_BPF,
+};
+
 static int __init bpf_lsm_init(void)
 {
-	security_add_hooks(bpf_lsm_hooks, ARRAY_SIZE(bpf_lsm_hooks), "bpf");
+	security_add_hooks(bpf_lsm_hooks, ARRAY_SIZE(bpf_lsm_hooks),
+			   &bpf_lsmid);
 	pr_info("LSM support for eBPF active\n");
 	return 0;
 }