[RFC PATCH v2 10/34] lsm: rework lsm_active_cnt and lsm_idlist[]

[Casey Schaufler]

On 7/21/2025 4:21 PM, Paul Moore wrote:
> Move the LSM active count and lsm_id list declarations out of a header
> that is visible across the kernel and into a header that is limited to
> the LSM framework.  This not only helps keep the include/linux headers
> smaller and cleaner, it helps prevent misuse of these variables.
>
> Signed-off-by: Paul Moore <paul at paul-moore.com>

One nit below, otherwise

Reviewed-by: Casey Schaufler <casey at schaufler-ca.com>


> ---
>  include/linux/security.h | 2 --
>  security/lsm.h           | 5 +++++
>  security/lsm_init.c      | 8 +-------
>  security/lsm_syscalls.c  | 2 ++
>  security/security.c      | 3 +++
>  5 files changed, 11 insertions(+), 9 deletions(-)
>
> diff --git a/include/linux/security.h b/include/linux/security.h
> index e8d9f6069f0c..c57a9a7499ea 100644
> --- a/include/linux/security.h
> +++ b/include/linux/security.h
> @@ -167,8 +167,6 @@ struct lsm_prop {
>  };
>  
>  extern const char *const lockdown_reasons[LOCKDOWN_CONFIDENTIALITY_MAX+1];
> -extern u32 lsm_active_cnt;
> -extern const struct lsm_id *lsm_idlist[];
>  
>  /* These functions are in security/commoncap.c */
>  extern int cap_capable(const struct cred *cred, struct user_namespace *ns,
> diff --git a/security/lsm.h b/security/lsm.h
> index 0e1731bad4a7..dbe755c45e57 100644
> --- a/security/lsm.h
> +++ b/security/lsm.h
> @@ -7,6 +7,11 @@
>  #define _LSM_H_
>  
>  #include <linux/lsm_hooks.h>
> +#include <linux/lsm_count.h>
> +
> +/* List of configured LSMs */
> +extern unsigned int lsm_active_cnt;
> +extern const struct lsm_id *lsm_idlist[];
>  
>  /* LSM blob configuration */
>  extern struct lsm_blob_sizes blob_sizes;
> diff --git a/security/lsm_init.c b/security/lsm_init.c
> index cbdfac31ede4..03d3e140e0b1 100644
> --- a/security/lsm_init.c
> +++ b/security/lsm_init.c
> @@ -22,8 +22,8 @@ static __initdata const char *lsm_order_cmdline;
>  static __initdata const char *lsm_order_legacy;
>  
>  /* Ordered list of LSMs to initialize. */
> -static __initdata struct lsm_info *lsm_order[MAX_LSM_COUNT + 1];
>  static __initdata struct lsm_info *lsm_exclusive;
> +static __initdata struct lsm_info *lsm_order[MAX_LSM_COUNT + 1];

I can't see there's a good reason for the reordering. I'm not
objecting to it, but it's curious.

>  
>  static __initdata bool debug;
>  #define init_debug(...)							\
> @@ -214,12 +214,6 @@ static void __init initialize_lsm(struct lsm_info *lsm)
>  	}
>  }
>  
> -/*
> - * Current index to use while initializing the lsm id list.
> - */
> -u32 lsm_active_cnt __ro_after_init;
> -const struct lsm_id *lsm_idlist[MAX_LSM_COUNT];
> -
>  /* Populate ordered LSMs list from comma-separated LSM name list. */
>  static void __init ordered_lsm_parse(const char *order, const char *origin)
>  {
> diff --git a/security/lsm_syscalls.c b/security/lsm_syscalls.c
> index 8440948a690c..5648b1f0ce9c 100644
> --- a/security/lsm_syscalls.c
> +++ b/security/lsm_syscalls.c
> @@ -17,6 +17,8 @@
>  #include <linux/lsm_hooks.h>
>  #include <uapi/linux/lsm.h>
>  
> +#include "lsm.h"
> +
>  /**
>   * lsm_name_to_attr - map an LSM attribute name to its ID
>   * @name: name of the attribute
> diff --git a/security/security.c b/security/security.c
> index e77791058086..106f225f4a80 100644
> --- a/security/security.c
> +++ b/security/security.c
> @@ -73,6 +73,9 @@ const char *const lockdown_reasons[LOCKDOWN_CONFIDENTIALITY_MAX + 1] = {
>  	[LOCKDOWN_CONFIDENTIALITY_MAX] = "confidentiality",
>  };
>  
> +unsigned int lsm_active_cnt __ro_after_init;
> +const struct lsm_id *lsm_idlist[MAX_LSM_COUNT];
> +
>  struct lsm_blob_sizes blob_sizes;
>  
>  struct kmem_cache *lsm_file_cache;