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Subject[SELINUX] Event notifications via Netlink
This patch against 2.6.3 implements Netlink based notifications for 
SELinux kernel events. This will allow SELinux userspace components to
maintain synchronization with kernel state.

For example, a userspace AVC (Access Vector Cache, the component that
makes access control decisions) is being implemented for use by Security
Enhanced X and SE-DBUS. These applications will request access control
decisions from the usersapce AVC, which will relay and cache decisions
from the kernel AVC.

When the security policy is reloaded or the enforcing mode is changed in
the kernel, the userspace AVC can be notified and take appropriate action
(e.g. flush cache).

Please apply.


include/linux/netlink.h | 1
include/linux/selinux_netlink.h | 37 +++++++++++++
security/selinux/Makefile | 2
security/selinux/netlink.c | 113 ++++++++++++++++++++++++++++++++++++++++
security/selinux/selinuxfs.c | 3 +
security/selinux/ss/services.c | 3 +
6 files changed, 158 insertions(+), 1 deletion(-)

- James
--
James Morris
<jmorris@redhat.com>

diff -urN -X dontdiff linux-2.6.3.o/include/linux/netlink.h linux-2.6.3.w/include/linux/netlink.h
--- linux-2.6.3.o/include/linux/netlink.h 2003-10-15 08:53:19.000000000 -0400
+++ linux-2.6.3.w/include/linux/netlink.h 2004-02-18 08:53:17.583636544 -0500
@@ -11,6 +11,7 @@
#define NETLINK_TCPDIAG 4 /* TCP socket monitoring */
#define NETLINK_NFLOG 5 /* netfilter/iptables ULOG */
#define NETLINK_XFRM 6 /* ipsec */
+#define NETLINK_SELINUX 7 /* SELinux event notifications */
#define NETLINK_ARPD 8
#define NETLINK_ROUTE6 11 /* af_inet6 route comm channel */
#define NETLINK_IP6_FW 13
diff -urN -X dontdiff linux-2.6.3.o/include/linux/selinux_netlink.h linux-2.6.3.w/include/linux/selinux_netlink.h
--- linux-2.6.3.o/include/linux/selinux_netlink.h 1969-12-31 19:00:00.000000000 -0500
+++ linux-2.6.3.w/include/linux/selinux_netlink.h 2004-02-18 08:53:17.584636392 -0500
@@ -0,0 +1,37 @@
+/*
+ * Netlink event notifications for SELinux.
+ *
+ * Author: James Morris <jmorris@redhat.com>
+ *
+ * Copyright (C) 2004 Red Hat, Inc., James Morris <jmorris@redhat.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2,
+ * as published by the Free Software Foundation.
+ */
+#ifndef _LINUX_SELINUX_NETLINK_H
+#define _LINUX_SELINUX_NETLINK_H
+
+/* Message types. */
+#define SELNL_MSG_BASE 0x10
+enum {
+ SELNL_MSG_SETENFORCE = SELNL_MSG_BASE,
+ SELNL_MSG_POLICYLOAD,
+ SELNL_MSG_MAX
+};
+
+/* Multicast groups */
+#define SELNL_GRP_NONE 0x00000000
+#define SELNL_GRP_AVC 0x00000001 /* AVC notifications */
+#define SELNL_GRP_ALL 0xffffffff
+
+/* Message structures */
+struct selnl_msg_setenforce {
+ u_int32_t val;
+};
+
+struct selnl_msg_policyload {
+ u_int32_t seqno;
+};
+
+#endif /* _LINUX_SELINUX_NETLINK_H */
diff -urN -X dontdiff linux-2.6.3.o/security/selinux/Makefile linux-2.6.3.w/security/selinux/Makefile
--- linux-2.6.3.o/security/selinux/Makefile 2004-02-04 08:39:07.000000000 -0500
+++ linux-2.6.3.w/security/selinux/Makefile 2004-02-18 08:53:17.605633200 -0500
@@ -4,7 +4,7 @@

obj-$(CONFIG_SECURITY_SELINUX) := selinux.o ss/

-selinux-y := avc.o hooks.o selinuxfs.o
+selinux-y := avc.o hooks.o selinuxfs.o netlink.o

selinux-$(CONFIG_SECURITY_NETWORK) += netif.o

diff -urN -X dontdiff linux-2.6.3.o/security/selinux/netlink.c linux-2.6.3.w/security/selinux/netlink.c
--- linux-2.6.3.o/security/selinux/netlink.c 1969-12-31 19:00:00.000000000 -0500
+++ linux-2.6.3.w/security/selinux/netlink.c 2004-02-18 09:01:54.288085528 -0500
@@ -0,0 +1,113 @@
+/*
+ * Netlink event notifications for SELinux.
+ *
+ * Author: James Morris <jmorris@redhat.com>
+ *
+ * Copyright (C) 2004 Red Hat, Inc., James Morris <jmorris@redhat.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2,
+ * as published by the Free Software Foundation.
+ */
+#include <linux/init.h>
+#include <linux/types.h>
+#include <linux/stddef.h>
+#include <linux/kernel.h>
+#include <linux/list.h>
+#include <linux/skbuff.h>
+#include <linux/netlink.h>
+#include <linux/selinux_netlink.h>
+
+static struct sock *selnl;
+
+static int selnl_msglen(int msgtype)
+{
+ int ret = 0;
+
+ switch (msgtype) {
+ case SELNL_MSG_SETENFORCE:
+ ret = sizeof(struct selnl_msg_setenforce);
+ break;
+
+ case SELNL_MSG_POLICYLOAD:
+ ret = sizeof(struct selnl_msg_policyload);
+ break;
+
+ default:
+ BUG();
+ }
+ return ret;
+}
+
+static void selnl_add_payload(struct nlmsghdr *nlh, int len, int msgtype, void *data)
+{
+ switch (msgtype) {
+ case SELNL_MSG_SETENFORCE: {
+ struct selnl_msg_setenforce *msg = NLMSG_DATA(nlh);
+
+ memset(msg, 0, len);
+ msg->val = *((int *)data);
+ break;
+ }
+
+ case SELNL_MSG_POLICYLOAD: {
+ struct selnl_msg_policyload *msg = NLMSG_DATA(nlh);
+
+ memset(msg, 0, len);
+ msg->seqno = *((u32 *)data);
+ break;
+ }
+
+ default:
+ BUG();
+ }
+}
+
+static void selnl_notify(int msgtype, void *data)
+{
+ int len;
+ unsigned char *tmp;
+ struct sk_buff *skb;
+ struct nlmsghdr *nlh;
+
+ len = selnl_msglen(msgtype);
+
+ skb = alloc_skb(NLMSG_SPACE(len), GFP_USER);
+ if (!skb)
+ goto oom;
+
+ tmp = skb->tail;
+ nlh = NLMSG_PUT(skb, 0, 0, msgtype, len);
+ selnl_add_payload(nlh, len, msgtype, data);
+ nlh->nlmsg_len = skb->tail - tmp;
+ netlink_broadcast(selnl, skb, 0, SELNL_GRP_AVC, GFP_USER);
+out:
+ return;
+
+nlmsg_failure:
+ kfree_skb(skb);
+oom:
+ printk(KERN_ERR "SELinux: OOM in %s\n", __FUNCTION__);
+ goto out;
+}
+
+void selnl_notify_setenforce(int val)
+{
+ selnl_notify(SELNL_MSG_SETENFORCE, &val);
+}
+
+void selnl_notify_policyload(u32 seqno)
+{
+ selnl_notify(SELNL_MSG_POLICYLOAD, &seqno);
+}
+
+static int __init selnl_init(void)
+{
+ selnl = netlink_kernel_create(NETLINK_SELINUX, NULL);
+ if (selnl == NULL)
+ panic("SELinux: Cannot create netlink socket.");
+ netlink_set_nonroot(NETLINK_SELINUX, NL_NONROOT_RECV);
+ return 0;
+}
+
+__initcall(selnl_init);
diff -urN -X dontdiff linux-2.6.3.o/security/selinux/selinuxfs.c linux-2.6.3.w/security/selinux/selinuxfs.c
--- linux-2.6.3.o/security/selinux/selinuxfs.c 2004-02-18 00:17:09.000000000 -0500
+++ linux-2.6.3.w/security/selinux/selinuxfs.c 2004-02-18 08:53:17.616631528 -0500
@@ -17,6 +17,8 @@
#include "security.h"
#include "objsec.h"

+extern void selnl_notify_setenforce(int val);
+
/* Check whether a task is allowed to use a security operation. */
int task_has_security(struct task_struct *tsk,
u32 perms)
@@ -111,6 +113,7 @@
selinux_enforcing = new_value;
if (selinux_enforcing)
avc_ss_reset(0);
+ selnl_notify_setenforce(selinux_enforcing);
}
length = count;
out:
diff -urN -X dontdiff linux-2.6.3.o/security/selinux/ss/services.c linux-2.6.3.w/security/selinux/ss/services.c
--- linux-2.6.3.o/security/selinux/ss/services.c 2004-02-18 00:17:09.000000000 -0500
+++ linux-2.6.3.w/security/selinux/ss/services.c 2004-02-18 08:53:17.619631072 -0500
@@ -28,6 +28,8 @@
#include "services.h"
#include "mls.h"

+extern void selnl_notify_policyload(u32 seqno);
+
static rwlock_t policy_rwlock = RW_LOCK_UNLOCKED;
#define POLICY_RDLOCK read_lock(&policy_rwlock)
#define POLICY_WRLOCK write_lock_irq(&policy_rwlock)
@@ -1052,6 +1054,7 @@
sidtab_destroy(&oldsidtab);

avc_ss_reset(seqno);
+ selnl_notify_policyload(seqno);

return 0;

-
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