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>

3 files changed, 73 insertions, 4 deletions

diff --git a/security/apparmor/include/policy_ns.h b/security/apparmor/include/policy_ns.h
index 23e7cb770226..2f7e480a34e0 100644
--- a/security/apparmor/include/policy_ns.h
+++ b/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 */
diff --git a/security/apparmor/policy.c b/security/apparmor/policy.c
index 0a99e5324da0..d95aae6bf710 100644
--- a/security/apparmor/policy.c
+++ b/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;
diff --git a/security/apparmor/policy_ns.c b/security/apparmor/policy_ns.c
index f3418a9e59b1..c05316809a5e 100644
--- a/security/apparmor/policy_ns.c
+++ b/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)
 {