lsm: add lsmprop_to_secctx hook

Add a new hook security_lsmprop_to_secctx() and its LSM specific
implementations. The LSM specific code will use the lsm_prop element
allocated for that module. This allows for the possibility that more
than one module may be called upon to translate a secid to a string,
as can occur in the audit code.

Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
[PM: subject line tweak]
Signed-off-by: Paul Moore <paul@paul-moore.com>

3 files changed, 26 insertions, 2 deletions

diff --git a/security/apparmor/include/secid.h b/security/apparmor/include/secid.h
index a912a5d5d04f..cc6d1c9f4a47 100644
--- a/security/apparmor/include/secid.h
+++ b/security/apparmor/include/secid.h
@@ -26,6 +26,8 @@ extern int apparmor_display_secid_mode;
 
 struct aa_label *aa_secid_to_label(u32 secid);
 int apparmor_secid_to_secctx(u32 secid, char **secdata, u32 *seclen);
+int apparmor_lsmprop_to_secctx(struct lsm_prop *prop, char **secdata,
+			       u32 *seclen);
 int apparmor_secctx_to_secid(const char *secdata, u32 seclen, u32 *secid);
 void apparmor_release_secctx(char *secdata, u32 seclen);
 
diff --git a/security/apparmor/lsm.c b/security/apparmor/lsm.c
index f5d05297d59e..a58b72ed246c 100644
--- a/security/apparmor/lsm.c
+++ b/security/apparmor/lsm.c
@@ -1517,6 +1517,7 @@ static struct security_hook_list apparmor_hooks[] __ro_after_init = {
 #endif
 
 	LSM_HOOK_INIT(secid_to_secctx, apparmor_secid_to_secctx),
+	LSM_HOOK_INIT(lsmprop_to_secctx, apparmor_lsmprop_to_secctx),
 	LSM_HOOK_INIT(secctx_to_secid, apparmor_secctx_to_secid),
 	LSM_HOOK_INIT(release_secctx, apparmor_release_secctx),
 
diff --git a/security/apparmor/secid.c b/security/apparmor/secid.c
index 83d3d1e6d9dc..34610888559f 100644
--- a/security/apparmor/secid.c
+++ b/security/apparmor/secid.c
@@ -61,10 +61,10 @@ struct aa_label *aa_secid_to_label(u32 secid)
 	return xa_load(&aa_secids, secid);
 }
 
-int apparmor_secid_to_secctx(u32 secid, char **secdata, u32 *seclen)
+static int apparmor_label_to_secctx(struct aa_label *label, char **secdata,
+				    u32 *seclen)
 {
 	/* TODO: cache secctx and ref count so we don't have to recreate */
-	struct aa_label *label = aa_secid_to_label(secid);
 	int flags = FLAG_VIEW_SUBNS | FLAG_HIDDEN_UNCONFINED | FLAG_ABS_ROOT;
 	int len;
 
@@ -90,6 +90,27 @@ int apparmor_secid_to_secctx(u32 secid, char **secdata, u32 *seclen)
 	return 0;
 }
 
+int apparmor_secid_to_secctx(u32 secid, char **secdata, u32 *seclen)
+{
+	struct aa_label *label = aa_secid_to_label(secid);
+
+	return apparmor_label_to_secctx(label, secdata, seclen);
+}
+
+int apparmor_lsmprop_to_secctx(struct lsm_prop *prop, char **secdata,
+			       u32 *seclen)
+{
+	struct aa_label *label;
+
+	/* scaffolding */
+	if (!prop->apparmor.label && prop->scaffold.secid)
+		label = aa_secid_to_label(prop->scaffold.secid);
+	else
+		label = prop->apparmor.label;
+
+	return apparmor_label_to_secctx(label, secdata, seclen);
+}
+
 int apparmor_secctx_to_secid(const char *secdata, u32 seclen, u32 *secid)
 {
 	struct aa_label *label;