Re: [PATCH v3 1/9] LSM: Identify modules by more than name
From: Greg KH <gregkh@linuxfoundation.org>
Date: 2022-11-24 05:40:52
Also in:
linux-api, lkml
On Wed, Nov 23, 2022 at 12:15:44PM -0800, Casey Schaufler wrote:
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.
What would be a "special case" that deserves a lower number?
quoted hunk ↗ jump to hunk
diff --git a/security/bpf/hooks.c b/security/bpf/hooks.c index e5971fa74fd7..20983ae8d31f 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[] __lsm_ro_after_init = { #define LSM_HOOK(RET, DEFAULT, NAME, ...) \@@ -15,9 +16,19 @@ static struct security_hook_list bpf_lsm_hooks[] __lsm_ro_after_init = { LSM_HOOK_INIT(task_free, bpf_task_storage_free), }; +/* + * slot has to be LSMBLOB_NEEDED because some of the hooks + * supplied by this module require a slot. + */ +struct lsm_id bpf_lsmid __lsm_ro_after_init = { + .lsm = "bpf", + .id = LSM_ID_BPF, +};
I do not understand this comment, what is LSMBLOB_NEEDED and how does that relate to the struct lsm_id? thanks, greg k-h