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 <p...@paul-moore.com>
Reviewed-by: Casey Schaufler <ca...@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);
> }
