Re: [RFC PATCH 20/29] smack: move initcalls to the LSM framework

[Kees Cook <kees@kernel.org>]

On Wed, Apr 09, 2025 at 02:50:05PM -0400, Paul Moore wrote:
> As the LSM framework only supports one LSM initcall callback for each
> initcall type, the init_smk_fs() and smack_nf_ip_init() functions were
> wrapped with a new function, smack_initcall() that is registered with
> the LSM framework.
> 
> Signed-off-by: Paul Moore <paul@paul-moore.com>
> ---
>  security/smack/smack.h           |  6 ++++++
>  security/smack/smack_lsm.c       | 16 ++++++++++++++++
>  security/smack/smack_netfilter.c |  4 +---
>  security/smack/smackfs.c         |  4 +---
>  4 files changed, 24 insertions(+), 6 deletions(-)
> 
> diff --git a/security/smack/smack.h b/security/smack/smack.h
> index bf6a6ed3946c..709e0d6cd5e1 100644
> --- a/security/smack/smack.h
> +++ b/security/smack/smack.h
> @@ -275,6 +275,12 @@ struct smk_audit_info {
>  #endif
>  };
>  
> +/*
> + * Initialization
> + */
> +int init_smk_fs(void);
> +int smack_nf_ip_init(void);
> +
>  /*
>   * These functions are in smack_access.c
>   */
> diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
> index e09b33fed5f0..80b129a0c92c 100644
> --- a/security/smack/smack_lsm.c
> +++ b/security/smack/smack_lsm.c
> @@ -5277,6 +5277,21 @@ static __init int smack_init(void)
>  	return 0;
>  }
>  
> +static int smack_initcall(void)
> +{
> +	int rc, rc_tmp;
> +
> +	rc_tmp = init_smk_fs();
> +	if (rc_tmp)
> +		rc = rc_tmp;
> +
> +	rc_tmp = smack_nf_ip_init();
> +	if (!rc && rc_tmp)
> +		rc = rc_tmp;
> +
> +	return rc;
> +}

This retains the existing behavior, but I think it'd be better to
evaluate if the init_smk_fs() call can be tied to the fs init hook
instead, yes? Then no new helper is needed, etc.

-Kees

> +
>  /*
>   * Smack requires early initialization in order to label
>   * all processes and objects when they are created.
> @@ -5286,4 +5301,5 @@ DEFINE_LSM(smack) = {
>  	.flags = LSM_FLAG_LEGACY_MAJOR | LSM_FLAG_EXCLUSIVE,
>  	.blobs = &smack_blob_sizes,
>  	.init = smack_init,
> +	.initcall_device = smack_initcall,
>  };
> diff --git a/security/smack/smack_netfilter.c b/security/smack/smack_netfilter.c
> index 8fd747b3653a..17ba578b1308 100644
> --- a/security/smack/smack_netfilter.c
> +++ b/security/smack/smack_netfilter.c
> @@ -68,7 +68,7 @@ static struct pernet_operations smack_net_ops = {
>  	.exit = smack_nf_unregister,
>  };
>  
> -static int __init smack_nf_ip_init(void)
> +int __init smack_nf_ip_init(void)
>  {
>  	if (smack_enabled == 0)
>  		return 0;
> @@ -76,5 +76,3 @@ static int __init smack_nf_ip_init(void)
>  	printk(KERN_DEBUG "Smack: Registering netfilter hooks\n");
>  	return register_pernet_subsys(&smack_net_ops);
>  }
> -
> -__initcall(smack_nf_ip_init);
> diff --git a/security/smack/smackfs.c b/security/smack/smackfs.c
> index 90a67e410808..d33dd0368807 100644
> --- a/security/smack/smackfs.c
> +++ b/security/smack/smackfs.c
> @@ -2980,7 +2980,7 @@ static struct vfsmount *smackfs_mount;
>   * Returns true if we were not chosen on boot or if
>   * we were chosen and filesystem registration succeeded.
>   */
> -static int __init init_smk_fs(void)
> +int __init init_smk_fs(void)
>  {
>  	int err;
>  	int rc;
> @@ -3023,5 +3023,3 @@ static int __init init_smk_fs(void)
>  
>  	return err;
>  }
> -
> -__initcall(init_smk_fs);
> -- 
> 2.49.0
> 

-- 
Kees Cook