Provide interfaces to map LSM slot numbers and LSM names.
Update the LSM registration code to save this information.
Acked-by: Paul Moore <[email protected]>
Reviewed-by: Kees Cook <[email protected]>
Signed-off-by: Casey Schaufler <[email protected]>
---
include/linux/security.h | 4 ++++
security/security.c | 45 ++++++++++++++++++++++++++++++++++++++++
2 files changed, 49 insertions(+)
diff --git a/include/linux/security.h b/include/linux/security.h
index ed51baa94a30..d00870d2b416 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -195,6 +195,10 @@ static inline bool lsmblob_equal(const struct lsmblob *bloba,
return !memcmp(bloba, blobb, sizeof(*bloba));
}
+/* Map lsm names to blob slot numbers */
+extern int lsm_name_to_slot(char *name);
+extern const char *lsm_slot_to_name(int slot);
+
/* These functions are in security/commoncap.c */
extern int cap_capable(const struct cred *cred, struct user_namespace *ns,
int cap, unsigned int opts);
diff --git a/security/security.c b/security/security.c
index 49fa61028da2..d1ddbb857af1 100644
--- a/security/security.c
+++ b/security/security.c
@@ -477,6 +477,50 @@ static int lsm_append(const char *new, char **result)
* Current index to use while initializing the lsmblob secid list.
*/
static int lsm_slot __lsm_ro_after_init;
+static struct lsm_id *lsm_slotlist[LSMBLOB_ENTRIES] __lsm_ro_after_init;
+
+/**
+ * lsm_name_to_slot - Report the slot number for a security module
+ * @name: name of the security module
+ *
+ * Look up the slot number for the named security module.
+ * Returns the slot number or LSMBLOB_INVALID if @name is not
+ * a registered security module name.
+ */
+int lsm_name_to_slot(char *name)
+{
+ int i;
+
+ for (i = 0; i < lsm_slot; i++)
+ if (strcmp(lsm_slotlist[i]->lsm, name) == 0)
+ return i;
+
+ return LSMBLOB_INVALID;
+}
+
+/**
+ * lsm_slot_to_name - Get the name of the security module in a slot
+ * @slot: index into the interface LSM slot list.
+ *
+ * Provide the name of the security module associated with
+ * a interface LSM slot.
+ *
+ * If @slot is LSMBLOB_INVALID return the value
+ * for slot 0 if it has been set, otherwise NULL.
+ *
+ * Returns a pointer to the name string or NULL.
+ */
+const char *lsm_slot_to_name(int slot)
+{
+ if (slot == LSMBLOB_INVALID)
+ slot = 0;
+ else if (slot >= LSMBLOB_ENTRIES || slot < 0)
+ return NULL;
+
+ if (lsm_slotlist[slot] == NULL)
+ return NULL;
+ return lsm_slotlist[slot]->lsm;
+}
/**
* security_add_hooks - Add a modules hooks to the hook lists.
@@ -498,6 +542,7 @@ void __init security_add_hooks(struct security_hook_list *hooks, int count,
if (lsmid->slot == LSMBLOB_NEEDED) {
if (lsm_slot >= LSMBLOB_ENTRIES)
panic("%s Too many LSMs registered.\n", __func__);
+ lsm_slotlist[lsm_slot] = lsmid;
lsmid->slot = lsm_slot++;
init_debug("%s assigned lsmblob slot %d\n", lsmid->lsm,
lsmid->slot);
--
2.35.1
On 4/18/22 07:59, Casey Schaufler wrote:
> Provide interfaces to map LSM slot numbers and LSM names.
> Update the LSM registration code to save this information.
>
> Acked-by: Paul Moore <[email protected]>
> Reviewed-by: Kees Cook <[email protected]>
> Signed-off-by: Casey Schaufler <[email protected]>
Reviewed-by: John Johansen <[email protected]>
> ---
> include/linux/security.h | 4 ++++
> security/security.c | 45 ++++++++++++++++++++++++++++++++++++++++
> 2 files changed, 49 insertions(+)
>
> diff --git a/include/linux/security.h b/include/linux/security.h
> index ed51baa94a30..d00870d2b416 100644
> --- a/include/linux/security.h
> +++ b/include/linux/security.h
> @@ -195,6 +195,10 @@ static inline bool lsmblob_equal(const struct lsmblob *bloba,
> return !memcmp(bloba, blobb, sizeof(*bloba));
> }
>
> +/* Map lsm names to blob slot numbers */
> +extern int lsm_name_to_slot(char *name);
> +extern const char *lsm_slot_to_name(int slot);
> +
> /* These functions are in security/commoncap.c */
> extern int cap_capable(const struct cred *cred, struct user_namespace *ns,
> int cap, unsigned int opts);
> diff --git a/security/security.c b/security/security.c
> index 49fa61028da2..d1ddbb857af1 100644
> --- a/security/security.c
> +++ b/security/security.c
> @@ -477,6 +477,50 @@ static int lsm_append(const char *new, char **result)
> * Current index to use while initializing the lsmblob secid list.
> */
> static int lsm_slot __lsm_ro_after_init;
> +static struct lsm_id *lsm_slotlist[LSMBLOB_ENTRIES] __lsm_ro_after_init;
> +
> +/**
> + * lsm_name_to_slot - Report the slot number for a security module
> + * @name: name of the security module
> + *
> + * Look up the slot number for the named security module.
> + * Returns the slot number or LSMBLOB_INVALID if @name is not
> + * a registered security module name.
> + */
> +int lsm_name_to_slot(char *name)
> +{
> + int i;
> +
> + for (i = 0; i < lsm_slot; i++)
> + if (strcmp(lsm_slotlist[i]->lsm, name) == 0)
> + return i;
> +
> + return LSMBLOB_INVALID;
> +}
> +
> +/**
> + * lsm_slot_to_name - Get the name of the security module in a slot
> + * @slot: index into the interface LSM slot list.
> + *
> + * Provide the name of the security module associated with
> + * a interface LSM slot.
> + *
> + * If @slot is LSMBLOB_INVALID return the value
> + * for slot 0 if it has been set, otherwise NULL.
> + *
> + * Returns a pointer to the name string or NULL.
> + */
> +const char *lsm_slot_to_name(int slot)
> +{
> + if (slot == LSMBLOB_INVALID)
> + slot = 0;
> + else if (slot >= LSMBLOB_ENTRIES || slot < 0)
> + return NULL;
> +
> + if (lsm_slotlist[slot] == NULL)
> + return NULL;
> + return lsm_slotlist[slot]->lsm;
> +}
>
> /**
> * security_add_hooks - Add a modules hooks to the hook lists.
> @@ -498,6 +542,7 @@ void __init security_add_hooks(struct security_hook_list *hooks, int count,
> if (lsmid->slot == LSMBLOB_NEEDED) {
> if (lsm_slot >= LSMBLOB_ENTRIES)
> panic("%s Too many LSMs registered.\n", __func__);
> + lsm_slotlist[lsm_slot] = lsmid;
> lsmid->slot = lsm_slot++;
> init_debug("%s assigned lsmblob slot %d\n", lsmid->lsm,
> lsmid->slot);