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Subject[PATCH][SELINUX] 2/7 Add netif controls
This patch against 2.6.1-mm2 adds netif access controls for SELinux, which 
allows network traffic to be controlled on the basis of associated
network interface.

Similar functionality was present in earlier SELinux implementations; this
is a rework within the constraints of the LSM hooks present in the
mainline kernel.

Please apply.

Makefile | 4
hooks.c | 165 +++++++++++++++++++++++++++++++++++++
include/netif.h | 30 ++++++
include/objsec.h | 7 +
netif.c | 239 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
5 files changed, 444 insertions(+), 1 deletion(-)

diff -urN -X dontdiff linux-2.6.1-rc2.pending/security/selinux/hooks.c linux-2.6.1-rc2.w1/security/selinux/hooks.c
--- linux-2.6.1-rc2.pending/security/selinux/hooks.c 2004-01-07 13:25:53.430125920 -0500
+++ linux-2.6.1-rc2.w1/security/selinux/hooks.c 2004-01-07 13:27:19.281074592 -0500
@@ -44,6 +44,7 @@
#include <linux/ext2_fs.h>
#include <linux/proc_fs.h>
#include <linux/kd.h>
+#include <linux/netfilter_ipv4.h>
#include <net/icmp.h>
#include <net/ip.h> /* for sysctl_local_port_range[] */
#include <net/tcp.h> /* struct or_callable used in sock_rcv_skb */
@@ -61,6 +62,7 @@

#include "avc.h"
#include "objsec.h"
+#include "netif.h"

#ifdef CONFIG_SECURITY_SELINUX_DEVELOP
int selinux_enforcing = 0;
@@ -2663,7 +2665,137 @@
return 0;
}

-#endif
+static int selinux_socket_sock_rcv_skb(struct sock *sk, struct sk_buff *skb)
+{
+ int err = 0;
+ u32 netif_perm;
+ struct socket *sock;
+ struct inode *inode;
+ struct net_device *dev;
+ struct sel_netif *netif;
+ struct netif_security_struct *nsec;
+ struct inode_security_struct *isec;
+ struct avc_audit_data ad;
+
+ /* Only IPv4 is supported here at this stage */
+ if (sk->sk_family != PF_INET)
+ goto out;
+
+ sock = sk->sk_socket;
+
+ /* TCP control messages don't always have a socket. */
+ if (!sock)
+ goto out;
+
+ inode = SOCK_INODE(sock);
+ if (!inode)
+ goto out;
+
+ dev = skb->dev;
+ if (!dev)
+ goto out;
+
+ netif = sel_netif_lookup(dev);
+ if (IS_ERR(netif)) {
+ err = PTR_ERR(netif);
+ goto out;
+ }
+
+ nsec = &netif->nsec;
+ isec = inode->i_security;
+
+ switch (isec->sclass) {
+ case SECCLASS_UDP_SOCKET:
+ netif_perm = NETIF__UDP_RECV;
+ break;
+
+ case SECCLASS_TCP_SOCKET:
+ netif_perm = NETIF__TCP_RECV;
+ break;
+
+ default:
+ netif_perm = NETIF__RAWIP_RECV;
+ break;
+ }
+
+ AVC_AUDIT_DATA_INIT(&ad, NET);
+ ad.u.net.netif = dev->name;
+ ad.u.net.skb = skb;
+
+ err = avc_has_perm(isec->sid, nsec->if_sid, SECCLASS_NETIF,
+ netif_perm, &nsec->avcr, &ad);
+
+ sel_netif_put(netif);
+out:
+ return err;
+}
+
+#ifdef CONFIG_NETFILTER
+static unsigned int selinux_ip_postroute_last(unsigned int hooknum,
+ struct sk_buff **pskb,
+ const struct net_device *in,
+ const struct net_device *out,
+ int (*okfn)(struct sk_buff *))
+{
+ int err = NF_ACCEPT;
+ u32 netif_perm;
+ struct socket *sock;
+ struct inode *inode;
+ struct sel_netif *netif;
+ struct sk_buff *skb = *pskb;
+ struct netif_security_struct *nsec;
+ struct inode_security_struct *isec;
+ struct avc_audit_data ad;
+ struct net_device *dev = (struct net_device *)out;
+
+ if (!skb->sk)
+ goto out;
+
+ sock = skb->sk->sk_socket;
+ if (!sock)
+ goto out;
+
+ inode = SOCK_INODE(sock);
+ if (!inode)
+ goto out;
+
+ netif = sel_netif_lookup(dev);
+ if (IS_ERR(netif)) {
+ err = NF_DROP;
+ goto out;
+ }
+
+ nsec = &netif->nsec;
+ isec = inode->i_security;
+
+ switch (isec->sclass) {
+ case SECCLASS_UDP_SOCKET:
+ netif_perm = NETIF__UDP_SEND;
+ break;
+
+ case SECCLASS_TCP_SOCKET:
+ netif_perm = NETIF__TCP_SEND;
+ break;
+
+ default:
+ netif_perm = NETIF__RAWIP_SEND;
+ break;
+ }
+
+ AVC_AUDIT_DATA_INIT(&ad, NET);
+ ad.u.net.netif = dev->name;
+ ad.u.net.skb = skb;
+
+ err = avc_has_perm(isec->sid, nsec->if_sid, SECCLASS_NETIF,
+ netif_perm, &nsec->avcr, &ad) ? NF_DROP : NF_ACCEPT;
+
+ sel_netif_put(netif);
+out:
+ return err;
+}
+#endif /* CONFIG_NETFILTER */
+
+#endif /* CONFIG_SECURITY_NETWORK */

static int ipc_alloc_security(struct task_struct *task,
struct kern_ipc_perm *perm,
@@ -3398,6 +3530,7 @@
.socket_getsockopt = selinux_socket_getsockopt,
.socket_setsockopt = selinux_socket_setsockopt,
.socket_shutdown = selinux_socket_shutdown,
+ .socket_sock_rcv_skb = selinux_socket_sock_rcv_skb,
#endif
};

@@ -3467,3 +3600,33 @@
all processes and objects when they are created. */
security_initcall(selinux_init);

+#if defined(CONFIG_SECURITY_NETWORK) && defined(CONFIG_NETFILTER)
+
+static struct nf_hook_ops selinux_ip_ops[] = {
+ { .hook = selinux_ip_postroute_last,
+ .owner = THIS_MODULE,
+ .pf = PF_INET,
+ .hooknum = NF_IP_POST_ROUTING,
+ .priority = NF_IP_PRI_SELINUX_LAST, },
+};
+
+static int __init selinux_nf_ip_init(void)
+{
+ int err = 0;
+
+ if (!selinux_enabled)
+ goto out;
+
+ printk(KERN_INFO "SELinux: Registering netfilter hooks\n");
+
+ err = nf_register_hook(&selinux_ip_ops[0]);
+ if (err)
+ panic("SELinux: nf_register_hook 0 error %d\n", err);
+
+out:
+ return err;
+}
+
+__initcall(selinux_nf_ip_init);
+
+#endif /* CONFIG_SECURITY_NETWORK && CONFIG_NETFILTER */
diff -urN -X dontdiff linux-2.6.1-rc2.pending/security/selinux/include/netif.h linux-2.6.1-rc2.w1/security/selinux/include/netif.h
--- linux-2.6.1-rc2.pending/security/selinux/include/netif.h 2004-01-07 13:25:53.440124400 -0500
+++ linux-2.6.1-rc2.w1/security/selinux/include/netif.h 2004-01-07 13:26:07.263023000 -0500
@@ -0,0 +1,30 @@
+/*
+ * Network interface table.
+ *
+ * Network interfaces (devices) do not have a security field, so we
+ * maintain a table associating each interface with a SID.
+ *
+ * Author: James Morris <jmorris@redhat.com>
+ *
+ * Copyright (C) 2003 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 _SELINUX_NETIF_H_
+#define _SELINUX_NETIF_H_
+
+struct sel_netif
+{
+ struct list_head list;
+ atomic_t users;
+ struct netif_security_struct nsec;
+ struct rcu_head rcu_head;
+};
+
+struct sel_netif *sel_netif_lookup(struct net_device *dev);
+void sel_netif_put(struct sel_netif *netif);
+
+#endif /* _SELINUX_NETIF_H_ */
+
diff -urN -X dontdiff linux-2.6.1-rc2.pending/security/selinux/include/objsec.h linux-2.6.1-rc2.w1/security/selinux/include/objsec.h
--- linux-2.6.1-rc2.pending/security/selinux/include/objsec.h 2004-01-07 13:25:53.441124248 -0500
+++ linux-2.6.1-rc2.w1/security/selinux/include/objsec.h 2004-01-07 13:26:07.264022848 -0500
@@ -93,6 +93,13 @@
unsigned char set;
};

+struct netif_security_struct {
+ struct net_device *dev; /* back pointer */
+ u32 if_sid; /* SID for this interface */
+ u32 msg_sid; /* default SID for messages received on this interface */
+ struct avc_entry_ref avcr; /* reference to permissions */
+};
+
extern int inode_security_set_sid(struct inode *inode, u32 sid);

#endif /* _SELINUX_OBJSEC_H_ */
diff -urN -X dontdiff linux-2.6.1-rc2.pending/security/selinux/Makefile linux-2.6.1-rc2.w1/security/selinux/Makefile
--- linux-2.6.1-rc2.pending/security/selinux/Makefile 2004-01-07 13:25:53.441124248 -0500
+++ linux-2.6.1-rc2.w1/security/selinux/Makefile 2004-01-07 13:26:07.264022848 -0500
@@ -6,5 +6,9 @@

selinux-objs := avc.o hooks.o selinuxfs.o

+ifeq ($(CONFIG_SECURITY_NETWORK),y)
+ selinux-objs += netif.o
+endif
+
EXTRA_CFLAGS += -Isecurity/selinux/include

diff -urN -X dontdiff linux-2.6.1-rc2.pending/security/selinux/netif.c linux-2.6.1-rc2.w1/security/selinux/netif.c
--- linux-2.6.1-rc2.pending/security/selinux/netif.c 2004-01-07 13:25:53.443123944 -0500
+++ linux-2.6.1-rc2.w1/security/selinux/netif.c 2004-01-07 13:27:19.283074288 -0500
@@ -0,0 +1,239 @@
+/*
+ * Network interface table.
+ *
+ * Network interfaces (devices) do not have a security field, so we
+ * maintain a table associating each interface with a SID.
+ *
+ * Author: James Morris <jmorris@redhat.com>
+ *
+ * Copyright (C) 2003 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/types.h>
+#include <linux/stddef.h>
+#include <linux/kernel.h>
+#include <linux/list.h>
+#include <linux/notifier.h>
+#include <linux/netdevice.h>
+#include <linux/rcupdate.h>
+
+#include "security.h"
+#include "objsec.h"
+#include "netif.h"
+
+#define SEL_NETIF_HASH_SIZE 64
+#define SEL_NETIF_HASH_MAX 1024
+
+#undef DEBUG
+
+#ifdef DEBUG
+#define DEBUGP printk
+#else
+#define DEBUGP(format, args...)
+#endif
+
+static u32 sel_netif_total;
+static LIST_HEAD(sel_netif_list);
+static spinlock_t sel_netif_lock = SPIN_LOCK_UNLOCKED;
+static struct sel_netif sel_netif_hash[SEL_NETIF_HASH_SIZE];
+
+static inline u32 sel_netif_hasfn(struct net_device *dev)
+{
+ return (dev->ifindex & (SEL_NETIF_HASH_SIZE - 1));
+}
+
+/*
+ * All of the devices should normally fit in the hash, so we optimize
+ * for that case.
+ */
+static struct sel_netif *sel_netif_find(struct net_device *dev)
+{
+ struct list_head *pos;
+ int idx = sel_netif_hasfn(dev);
+
+ __list_for_each_rcu(pos, &sel_netif_hash[idx].list) {
+ struct sel_netif *netif = list_entry(pos,
+ struct sel_netif, list);
+ if (likely(netif->nsec.dev == dev))
+ return netif;
+ }
+ return NULL;
+}
+
+static int sel_netif_insert(struct sel_netif *netif)
+{
+ int idx, ret = 0;
+
+ if (sel_netif_total >= SEL_NETIF_HASH_MAX) {
+ ret = -ENOSPC;
+ goto out;
+ }
+
+ idx = sel_netif_hasfn(netif->nsec.dev);
+ list_add_rcu(&netif->list, &sel_netif_hash[idx].list);
+ atomic_set(&netif->users, 1);
+ sel_netif_total++;
+out:
+ return ret;
+}
+
+struct sel_netif *sel_netif_lookup(struct net_device *dev)
+{
+ int ret;
+ struct sel_netif *netif, *new;
+ struct netif_security_struct *nsec;
+
+ rcu_read_lock();
+ netif = sel_netif_find(dev);
+ rcu_read_unlock();
+
+ if (likely(netif != NULL))
+ goto out_hold;
+
+ new = kmalloc(sizeof(*new), GFP_ATOMIC);
+ if (!new) {
+ netif = ERR_PTR(-ENOMEM);
+ goto out;
+ }
+
+ memset(new, 0, sizeof(*new));
+ nsec = &new->nsec;
+
+ ret = security_netif_sid(dev->name, &nsec->if_sid, &nsec->msg_sid);
+ if (ret < 0) {
+ kfree(new);
+ netif = ERR_PTR(ret);
+ goto out;
+ }
+
+ nsec->dev = dev;
+
+ spin_lock_bh(&sel_netif_lock);
+
+ netif = sel_netif_find(dev);
+ if (netif) {
+ spin_unlock_bh(&sel_netif_lock);
+ kfree(new);
+ goto out_hold;
+ }
+
+ sel_netif_insert(new);
+ spin_unlock_bh(&sel_netif_lock);
+
+ netif = new;
+
+ DEBUGP("new: ifindex=%u name=%s if_sid=%u msg_sid=%u\n", dev->ifindex, dev->name,
+ nsec->if_sid, nsec->msg_sid);
+out_hold:
+ atomic_inc(&netif->users);
+out:
+ return netif;
+}
+
+static void sel_netif_free(void *p)
+{
+ struct sel_netif *netif = p;
+
+ DEBUGP("%s: %s\n", __FUNCTION__, netif->nsec.dev->name);
+ kfree(netif);
+}
+
+static void sel_netif_destroy(struct sel_netif *netif)
+{
+ DEBUGP("%s: %s\n", __FUNCTION__, netif->nsec.dev->name);
+
+ spin_lock_bh(&sel_netif_lock);
+ list_del_rcu(&netif->list);
+ sel_netif_total--;
+ spin_unlock_bh(&sel_netif_lock);
+
+ call_rcu(&netif->rcu_head, sel_netif_free, netif);
+}
+
+void sel_netif_put(struct sel_netif *netif)
+{
+ if (atomic_dec_and_test(&netif->users))
+ sel_netif_destroy(netif);
+}
+
+static void sel_netif_kill(struct net_device *dev)
+{
+ struct sel_netif *netif;
+
+ rcu_read_lock();
+ netif = sel_netif_find(dev);
+ rcu_read_unlock();
+
+ /* Drop internal reference */
+ if (netif)
+ sel_netif_put(netif);
+}
+
+static void sel_netif_flush(void)
+{
+ int idx;
+
+ for (idx = 0; idx < SEL_NETIF_HASH_SIZE; idx++) {
+ struct list_head *pos;
+
+ list_for_each_rcu(pos, &sel_netif_hash[idx].list) {
+ struct sel_netif *netif;
+
+ netif = list_entry(pos, struct sel_netif, list);
+ if (netif)
+ sel_netif_put(netif);
+ }
+ }
+}
+
+static int sel_netif_avc_callback(u32 event, u32 ssid, u32 tsid,
+ u16 class, u32 perms, u32 *retained)
+{
+ if (event == AVC_CALLBACK_RESET) {
+ sel_netif_flush();
+ synchronize_net();
+ }
+ return 0;
+}
+
+static int sel_netif_netdev_notifier_handler(struct notifier_block *this,
+ unsigned long event, void *ptr)
+{
+ struct net_device *dev = ptr;
+
+ if (event == NETDEV_DOWN)
+ sel_netif_kill(dev);
+
+ return NOTIFY_DONE;
+}
+
+static struct notifier_block sel_netif_netdev_notifier = {
+ .notifier_call = sel_netif_netdev_notifier_handler,
+};
+
+static __init int sel_netif_init(void)
+{
+ int i, err = 0;
+
+ if (!selinux_enabled)
+ goto out;
+
+ for (i = 0; i < SEL_NETIF_HASH_SIZE; i++)
+ INIT_LIST_HEAD(&sel_netif_hash[i].list);
+
+ register_netdevice_notifier(&sel_netif_netdev_notifier);
+
+ err = avc_add_callback(sel_netif_avc_callback, AVC_CALLBACK_RESET,
+ SECSID_NULL, SECSID_NULL, SECCLASS_NULL, 0);
+ if (err)
+ panic("avc_add_callback() failed, error %d\n", err);
+
+out:
+ return err;
+}
+
+__initcall(sel_netif_init);
+

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