AppArmor: mediation of non file objects

ipc:
AppArmor ipc is currently limited to mediation done by file mediation
and basic ptrace tests.  Improved mediation is a wip.

rlimits:
AppArmor provides basic abilities to set and control rlimits at
a per profile level.  Only resources specified in a profile are controled
or set.  AppArmor rules set the hard limit to a value <= to the current
hard limit (ie. they can not currently raise hard limits), and if
necessary will lower the soft limit to the new hard limit value.

AppArmor does not track resource limits to reset them when a profile
is left so that children processes inherit the limits set by the
parent even if they are not confined by the same profile.

Capabilities:  AppArmor provides a per profile mask of capabilities,
that will further restrict.

Signed-off-by: John Johansen <john.johansen@canonical.com>
Signed-off-by: James Morris <jmorris@namei.org>

1 files changed, 134 insertions, 0 deletions

diff --git a/security/apparmor/resource.c b/security/apparmor/resource.c
new file mode 100644
index 0000000..4a368f1
--- /dev/null
+++ b/security/apparmor/resource.c
@@ -0,0 +1,134 @@
+/*
+ * AppArmor security module
+ *
+ * This file contains AppArmor resource mediation and attachment
+ *
+ * Copyright (C) 1998-2008 Novell/SUSE
+ * Copyright 2009-2010 Canonical Ltd.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation, version 2 of the
+ * License.
+ */
+
+#include <linux/audit.h>
+
+#include "include/audit.h"
+#include "include/resource.h"
+#include "include/policy.h"
+
+/*
+ * Table of rlimit names: we generate it from resource.h.
+ */
+#include "rlim_names.h"
+
+/* audit callback for resource specific fields */
+static void audit_cb(struct audit_buffer *ab, void *va)
+{
+	struct common_audit_data *sa = va;
+
+	audit_log_format(ab, " rlimit=%s value=%lu",
+			 rlim_names[sa->aad.rlim.rlim], sa->aad.rlim.max);
+}
+
+/**
+ * audit_resource - audit setting resource limit
+ * @profile: profile being enforced  (NOT NULL)
+ * @resoure: rlimit being auditing
+ * @value: value being set
+ * @error: error value
+ *
+ * Returns: 0 or sa->error else other error code on failure
+ */
+static int audit_resource(struct aa_profile *profile, unsigned int resource,
+			  unsigned long value, int error)
+{
+	struct common_audit_data sa;
+
+	COMMON_AUDIT_DATA_INIT(&sa, NONE);
+	sa.aad.op = OP_SETRLIMIT,
+	sa.aad.rlim.rlim = resource;
+	sa.aad.rlim.max = value;
+	sa.aad.error = error;
+	return aa_audit(AUDIT_APPARMOR_AUTO, profile, GFP_KERNEL, &sa,
+			audit_cb);
+}
+
+/**
+ * aa_map_resouce - map compiled policy resource to internal #
+ * @resource: flattened policy resource number
+ *
+ * Returns: resource # for the current architecture.
+ *
+ * rlimit resource can vary based on architecture, map the compiled policy
+ * resource # to the internal representation for the architecture.
+ */
+int aa_map_resource(int resource)
+{
+	return rlim_map[resource];
+}
+
+/**
+ * aa_task_setrlimit - test permission to set an rlimit
+ * @profile - profile confining the task  (NOT NULL)
+ * @resource - the resource being set
+ * @new_rlim - the new resource limit  (NOT NULL)
+ *
+ * Control raising the processes hard limit.
+ *
+ * Returns: 0 or error code if setting resource failed
+ */
+int aa_task_setrlimit(struct aa_profile *profile, unsigned int resource,
+		      struct rlimit *new_rlim)
+{
+	int error = 0;
+
+	if (profile->rlimits.mask & (1 << resource) &&
+	    new_rlim->rlim_max > profile->rlimits.limits[resource].rlim_max)
+
+		error = audit_resource(profile, resource, new_rlim->rlim_max,
+			-EACCES);
+
+	return error;
+}
+
+/**
+ * __aa_transition_rlimits - apply new profile rlimits
+ * @old: old profile on task  (NOT NULL)
+ * @new: new profile with rlimits to apply  (NOT NULL)
+ */
+void __aa_transition_rlimits(struct aa_profile *old, struct aa_profile *new)
+{
+	unsigned int mask = 0;
+	struct rlimit *rlim, *initrlim;
+	int i;
+
+	/* for any rlimits the profile controlled reset the soft limit
+	 * to the less of the tasks hard limit and the init tasks soft limit
+	 */
+	if (old->rlimits.mask) {
+		for (i = 0, mask = 1; i < RLIM_NLIMITS; i++, mask <<= 1) {
+			if (old->rlimits.mask & mask) {
+				rlim = current->signal->rlim + i;
+				initrlim = init_task.signal->rlim + i;
+				rlim->rlim_cur = min(rlim->rlim_max,
+						     initrlim->rlim_cur);
+			}
+		}
+	}
+
+	/* set any new hard limits as dictated by the new profile */
+	if (!new->rlimits.mask)
+		return;
+	for (i = 0, mask = 1; i < RLIM_NLIMITS; i++, mask <<= 1) {
+		if (!(new->rlimits.mask & mask))
+			continue;
+
+		rlim = current->signal->rlim + i;
+		rlim->rlim_max = min(rlim->rlim_max,
+				     new->rlimits.limits[i].rlim_max);
+		/* soft limit should not exceed hard limit */
+		rlim->rlim_cur = min(rlim->rlim_cur, rlim->rlim_max);
+	}
+}