Commit 30603941 authored Mar 03, 2026 by John Johansen

apparmor: fix: limit the number of levels of policy namespaces



Currently the number of policy namespaces is not bounded relying on
the user namespace limit. However policy namespaces aren't strictly
tied to user namespaces and it is possible to create them and nest
them arbitrarily deep which can be used to exhaust system resource.

Hard cap policy namespaces to the same depth as user namespaces.

Fixes: c88d4c7b ("AppArmor: core policy routines")
Reported-by: Qualys Security Advisory <qsa@qualys.com>
Reviewed-by: Ryan Lee <ryan.lee@canonical.com>
Reviewed-by: Cengiz Can <cengiz.can@canonical.com>
Signed-off-by: John Johansen <john.johansen@canonical.com>

parent ab092646

security/apparmor/include/policy_ns.h

+2 −0

Original line number	Diff line number	Diff line
		@@ -18,6 +18,8 @@
		#include "label.h"
		#include "policy.h"

		/* Match max depth of user namespaces */
		#define MAX_NS_DEPTH 32

		/* struct aa_ns_acct - accounting of profiles in namespace
		* @max_size: maximum space allowed for all profiles in namespace

security/apparmor/policy_ns.c

+2 −0

Original line number	Diff line number	Diff line
		@@ -223,6 +223,8 @@ static struct aa_ns __aa_create_ns(struct aa_ns parent, const char *name,
		AA_BUG(!name);
		AA_BUG(!mutex_is_locked(&parent->lock));

		if (parent->level > MAX_NS_DEPTH)
		return ERR_PTR(-ENOSPC);
		ns = alloc_ns(parent->base.hname, name);
		if (!ns)
		return ERR_PTR(-ENOMEM);