apparmor: add namespace lookup fns()

Currently lookups are restricted to a single ns component in the
path. However when namespaces are allowed to have separate views, and
scopes this will not be sufficient, as it will be possible to have
a multiple component ns path in scope.

Add some ns lookup fns() to allow this and use them.

Signed-off-by: John Johansen <john.johansen@canonical.com>

security/apparmor/include/policy_ns.h

@@ -89,6 +89,8 @@ void aa_free_ns_kref(struct kref *kref);
 
 struct aa_ns *aa_find_ns(struct aa_ns *root, const char *name);
 struct aa_ns *aa_findn_ns(struct aa_ns *root, const char *name, size_t n);
+struct aa_ns *__aa_lookupn_ns(struct aa_ns *view, const char *hname, size_t n);
+struct aa_ns *aa_lookupn_ns(struct aa_ns *view, const char *name, size_t n);
 struct aa_ns *__aa_find_or_create_ns(struct aa_ns *parent, const char *name,
 				     struct dentry *dir);
 struct aa_ns *aa_prepare_ns(struct aa_ns *root, const char *name);
@@ -148,4 +150,15 @@ static inline struct aa_ns *__aa_find_ns(struct list_head *head,
 	return __aa_findn_ns(head, name, strlen(name));
 }
 
+static inline struct aa_ns *__aa_lookup_ns(struct aa_ns *base,
+					   const char *hname)
+{
+	return __aa_lookupn_ns(base, hname, strlen(hname));
+}
+
+static inline struct aa_ns *aa_lookup_ns(struct aa_ns *view, const char *name)
+{
+	return aa_lookupn_ns(view, name, strlen(name));
+}
+
 #endif /* AA_NAMESPACE_H */

security/apparmor/policy.c

@@ -566,7 +566,7 @@ struct aa_profile *aa_fqlookupn_profile(struct aa_profile *base,
 
 	name = aa_splitn_fqname(fqname, n, &ns_name, &ns_len);
 	if (ns_name) {
-		ns = aa_findn_ns(base->ns, ns_name, ns_len);
+		ns = aa_lookupn_ns(base->ns, ns_name, ns_len);
 		if (!ns)
 			return NULL;
 	} else
@@ -1108,7 +1108,7 @@ ssize_t aa_remove_profiles(struct aa_ns *view, struct aa_profile *subj,
 	struct aa_ns *root = NULL, *ns = NULL;
 	struct aa_profile *profile = NULL;
 	const char *name = fqname, *info = NULL;
-	char *ns_name = NULL;
+	const char *ns_name = NULL;
 	ssize_t error = 0;
 
 	if (*fqname == 0) {
@@ -1120,9 +1120,11 @@ ssize_t aa_remove_profiles(struct aa_ns *view, struct aa_profile *subj,
 	root = view;
 
 	if (fqname[0] == ':') {
-		name = aa_split_fqname(fqname, &ns_name);
+		size_t ns_len;
+
+		name = aa_splitn_fqname(fqname, size, &ns_name, &ns_len);
 		/* released below */
-		ns = aa_find_ns(root, ns_name);
+		ns = aa_lookupn_ns(root, ns_name, ns_len);
 		if (!ns) {
 			info = "namespace does not exist";
 			error = -ENOENT;

security/apparmor/policy_ns.c

@@ -183,6 +183,60 @@ struct aa_ns *aa_find_ns(struct aa_ns *root, const char *name)
 	return aa_findn_ns(root, name, strlen(name));
 }
 
+/**
+ * __aa_lookupn_ns - lookup the namespace matching @hname
+ * @base: base list to start looking up profile name from  (NOT NULL)
+ * @hname: hierarchical ns name  (NOT NULL)
+ * @n: length of @hname
+ *
+ * Requires: rcu_read_lock be held
+ *
+ * Returns: unrefcounted ns pointer or NULL if not found
+ *
+ * Do a relative name lookup, recursing through profile tree.
+ */
+struct aa_ns *__aa_lookupn_ns(struct aa_ns *view, const char *hname, size_t n)
+{
+	struct aa_ns *ns = view;
+	const char *split;
+
+	for (split = strnstr(hname, "//", n); split;
+	     split = strnstr(hname, "//", n)) {
+		ns = __aa_findn_ns(&ns->sub_ns, hname, split - hname);
+		if (!ns)
+			return NULL;
+
+		n -= split + 2 - hname;
+		hname = split + 2;
+	}
+
+	if (n)
+		return __aa_findn_ns(&ns->sub_ns, hname, n);
+	return NULL;
+}
+
+/**
+ * aa_lookupn_ns  -  look up a policy namespace relative to @view
+ * @view: namespace to search in  (NOT NULL)
+ * @name: name of namespace to find  (NOT NULL)
+ * @n: length of @name
+ *
+ * Returns: a refcounted namespace on the list, or NULL if no namespace
+ *          called @name exists.
+ *
+ * refcount released by caller
+ */
+struct aa_ns *aa_lookupn_ns(struct aa_ns *view, const char *name, size_t n)
+{
+	struct aa_ns *ns = NULL;
+
+	rcu_read_lock();
+	ns = aa_get_ns(__aa_lookupn_ns(view, name, n));
+	rcu_read_unlock();
+
+	return ns;
+}
+
 static struct aa_ns *__aa_create_ns(struct aa_ns *parent, const char *name,
 				    struct dentry *dir)
 {