[PATCH v3 3/9] LSM: Maintain a table of LSM attribute data

From: Casey Schaufler
Date: Wed Nov 23 2022 - 15:18:38 EST


As LSMs are registered add their lsm_id pointers to a table.
This will be used later for attribute reporting.

Signed-off-by: Casey Schaufler <casey@xxxxxxxxxxxxxxxx>
---
include/linux/security.h | 18 ++++++++++++++++++
security/security.c | 18 ++++++++++++++++++
2 files changed, 36 insertions(+)

diff --git a/include/linux/security.h b/include/linux/security.h
index ca1b7109c0db..5b7d486ae1f3 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -138,6 +138,24 @@ enum lockdown_reason {

extern const char *const lockdown_reasons[LOCKDOWN_CONFIDENTIALITY_MAX+1];

+/* The capability module is accounted for by CONFIG_SECURITY */
+#define LSMID_ENTRIES ( \
+ (IS_ENABLED(CONFIG_SECURITY) ? 1 : 0) + \
+ (IS_ENABLED(CONFIG_SECURITY_SELINUX) ? 1 : 0) + \
+ (IS_ENABLED(CONFIG_SECURITY_SMACK) ? 1 : 0) + \
+ (IS_ENABLED(CONFIG_SECURITY_TOMOYO) ? 1 : 0) + \
+ (IS_ENABLED(CONFIG_SECURITY_IMA) ? 1 : 0) + \
+ (IS_ENABLED(CONFIG_SECURITY_APPARMOR) ? 1 : 0) + \
+ (IS_ENABLED(CONFIG_SECURITY_YAMA) ? 1 : 0) + \
+ (IS_ENABLED(CONFIG_SECURITY_LOADPIN) ? 1 : 0) + \
+ (IS_ENABLED(CONFIG_SECURITY_SAFESETID) ? 1 : 0) + \
+ (IS_ENABLED(CONFIG_SECURITY_LOCKDOWN) ? 1 : 0) + \
+ (IS_ENABLED(CONFIG_BPF_LSM) ? 1 : 0) + \
+ (IS_ENABLED(CONFIG_SECURITY_LANDLOCK) ? 1 : 0))
+
+extern u32 lsm_active_cnt;
+extern struct lsm_id *lsm_idlist[];
+
/* 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 b2eb0ccd954b..6e8ed58423d7 100644
--- a/security/security.c
+++ b/security/security.c
@@ -28,6 +28,7 @@
#include <linux/backing-dev.h>
#include <linux/string.h>
#include <linux/msg.h>
+#include <uapi/linux/lsm.h>
#include <net/flow.h>

#define MAX_LSM_EVM_XATTR 2
@@ -320,6 +321,12 @@ static void __init lsm_early_task(struct task_struct *task);

static int lsm_append(const char *new, char **result);

+/*
+ * Current index to use while initializing the lsm id list.
+ */
+u32 lsm_active_cnt __lsm_ro_after_init;
+struct lsm_id *lsm_idlist[LSMID_ENTRIES] __lsm_ro_after_init;
+
static void __init ordered_lsm_init(void)
{
struct lsm_info **lsm;
@@ -364,6 +371,7 @@ static void __init ordered_lsm_init(void)
for (lsm = ordered_lsms; *lsm; lsm++)
initialize_lsm(*lsm);

+ init_debug("lsm count = %d\n", lsm_active_cnt);
kfree(ordered_lsms);
}

@@ -485,6 +493,16 @@ void __init security_add_hooks(struct security_hook_list *hooks, int count,
{
int i;

+ /*
+ * A security module may call security_add_hooks() more
+ * than once. Landlock is one such case.
+ */
+ if (lsm_active_cnt == 0 || lsm_idlist[lsm_active_cnt -1] != lsmid)
+ lsm_idlist[lsm_active_cnt++] = lsmid;
+
+ if (lsm_active_cnt > LSMID_ENTRIES)
+ panic("%s Too many LSMs registered.\n", __func__);
+
for (i = 0; i < count; i++) {
hooks[i].lsmid = lsmid;
hlist_add_tail_rcu(&hooks[i].list, hooks[i].head);
--
2.38.1