[RFC PATCH v2 14/34] lsm: rename/rework append_ordered_lsm() into lsm_order_append()

[Casey Schaufler]

On 7/21/2025 4:21 PM, Paul Moore wrote:
> Rename append_ordered_lsm() to lsm_order_append() to better match
> convention and do some rework.  The rework includes moving the
> LSM_FLAG_EXCLUSIVE logic from lsm_prepare() to lsm_order_append()
> in order to consolidate the individual LSM append/activation code,
> and adding logic to skip appending explicitly disabled LSMs to the
> active LSM list.
>
> Signed-off-by: Paul Moore <paul at paul-moore.com>

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


> ---
>  security/lsm_init.c | 76 +++++++++++++++++++++++++--------------------
>  1 file changed, 43 insertions(+), 33 deletions(-)
>
> diff --git a/security/lsm_init.c b/security/lsm_init.c
> index 01825da2755f..8c632ab77da9 100644
> --- a/security/lsm_init.c
> +++ b/security/lsm_init.c
> @@ -124,24 +124,48 @@ static bool __init lsm_order_exists(struct lsm_info *lsm)
>  	return false;
>  }
>  
> -/* Append an LSM to the list of ordered LSMs to initialize. */
> -static int last_lsm __initdata;
> -static void __init append_ordered_lsm(struct lsm_info *lsm, const char *from)
> +/**
> + * lsm_order_append - Append a LSM to the ordered list
> + * @lsm: LSM definition
> + * @src: source of the addition
> + *
> + * Append @lsm to the enabled LSM array after ensuring that it hasn't been
> + * explicitly disabled, is a duplicate entry, or would run afoul of the
> + * LSM_FLAG_EXCLUSIVE logic.
> + */
> +static void __init lsm_order_append(struct lsm_info *lsm, const char *src)
>  {
>  	/* Ignore duplicate selections. */
>  	if (lsm_order_exists(lsm))
>  		return;
>  
> -	if (WARN(last_lsm == MAX_LSM_COUNT, "%s: out of LSM static calls!?\n", from))
> -		return;
> +	/* Skip explicitly disabled LSMs. */
> +	if (lsm->enabled && !lsm_is_enabled(lsm))
> +		goto out;
>  
> -	/* Enable this LSM, if it is not already set. */
> -	if (!lsm->enabled)
> -		lsm->enabled = &lsm_enabled_true;
> -	lsm_order[last_lsm] = lsm;
> -	lsm_idlist[last_lsm++] = lsm->id;
> +	if (WARN(lsm_active_cnt == MAX_LSM_COUNT,
> +		 "%s: out of LSM static calls!?\n", src)) {
> +		lsm_enabled_set(lsm, false);
> +		goto out;
> +	}
>  
> -	init_debug("%s ordered: %s (%s)\n", from, lsm->id->name,
> +	if (lsm->flags & LSM_FLAG_EXCLUSIVE) {
> +		if (lsm_exclusive) {
> +			init_debug("exclusive disabled: %s\n", lsm->id->name);
> +			lsm_enabled_set(lsm, false);
> +			goto out;
> +		} else {
> +			init_debug("exclusive chosen:   %s\n", lsm->id->name);
> +			lsm_exclusive = lsm;
> +		}
> +	}
> +
> +	lsm_enabled_set(lsm, true);
> +	lsm_order[lsm_active_cnt] = lsm;
> +	lsm_idlist[lsm_active_cnt++] = lsm->id;
> +
> +out:
> +	init_debug("%s ordered: %s (%s)\n", src, lsm->id->name,
>  		   lsm_is_enabled(lsm) ? "enabled" : "disabled");
>  }
>  
> @@ -163,26 +187,12 @@ static void __init lsm_set_blob_size(int *need, int *lbs)
>   */
>  static void __init lsm_prepare(struct lsm_info *lsm)
>  {
> -	struct lsm_blob_sizes *blobs;
> +	struct lsm_blob_sizes *blobs = lsm->blobs;
>  
> -	if (!lsm_is_enabled(lsm)) {
> -		lsm_enabled_set(lsm, false);
> +	if (!blobs)
>  		return;
> -	} else if ((lsm->flags & LSM_FLAG_EXCLUSIVE) && lsm_exclusive) {
> -		init_debug("exclusive disabled: %s\n", lsm->id->name);
> -		lsm_enabled_set(lsm, false);
> -		return;
> -	}
> -
> -	/* Mark the LSM as enabled. */
> -	lsm_enabled_set(lsm, true);
> -	if ((lsm->flags & LSM_FLAG_EXCLUSIVE) && !lsm_exclusive) {
> -		init_debug("exclusive chosen:   %s\n", lsm->id->name);
> -		lsm_exclusive = lsm;
> -	}
>  
>  	/* Register the LSM blob sizes. */
> -	blobs = lsm->blobs;
>  	lsm_set_blob_size(&blobs->lbs_cred, &blob_sizes.lbs_cred);
>  	lsm_set_blob_size(&blobs->lbs_file, &blob_sizes.lbs_file);
>  	lsm_set_blob_size(&blobs->lbs_ib, &blob_sizes.lbs_ib);
> @@ -224,7 +234,7 @@ static void __init ordered_lsm_parse(const char *order, const char *origin)
>  	/* LSM_ORDER_FIRST is always first. */
>  	lsm_for_each_raw(lsm) {
>  		if (lsm->order == LSM_ORDER_FIRST)
> -			append_ordered_lsm(lsm, "  first");
> +			lsm_order_append(lsm, "  first");
>  	}
>  
>  	/* Process "security=", if given. */
> @@ -256,7 +266,7 @@ static void __init ordered_lsm_parse(const char *order, const char *origin)
>  		lsm_for_each_raw(lsm) {
>  			if (strcmp(lsm->id->name, name) == 0) {
>  				if (lsm->order == LSM_ORDER_MUTABLE)
> -					append_ordered_lsm(lsm, origin);
> +					lsm_order_append(lsm, origin);
>  				found = true;
>  			}
>  		}
> @@ -272,14 +282,14 @@ static void __init ordered_lsm_parse(const char *order, const char *origin)
>  			if (lsm_order_exists(lsm))
>  				continue;
>  			if (strcmp(lsm->id->name, lsm_order_legacy) == 0)
> -				append_ordered_lsm(lsm, "security=");
> +				lsm_order_append(lsm, "security=");
>  		}
>  	}
>  
>  	/* LSM_ORDER_LAST is always last. */
>  	lsm_for_each_raw(lsm) {
>  		if (lsm->order == LSM_ORDER_LAST)
> -			append_ordered_lsm(lsm, "   last");
> +			lsm_order_append(lsm, "   last");
>  	}
>  
>  	/* Disable all LSMs not in the ordered list. */
> @@ -409,8 +419,8 @@ int __init early_security_init(void)
>  	struct lsm_info *lsm;
>  
>  	lsm_early_for_each_raw(lsm) {
> -		if (!lsm->enabled)
> -			lsm->enabled = &lsm_enabled_true;
> +		lsm_enabled_set(lsm, true);
> +		lsm_order_append(lsm, "early");
>  		lsm_prepare(lsm);
>  		initialize_lsm(lsm);
>  	}