ftrace: Synchronize the initialization of ftrace_opsgrafted

There's some internal state that ftrace_ops needs to have set, but since
it can be declared outside of the ftrace.c code, it calls
ftrace_ops_init() on the ops in every global function. The issue is that
if two tasks call it on the same ops at the same time it is possible to
have the initialization of one corrupt the initialization of the other
call.

Create a ops_mutex to use to synchronize every initialization of the
ftrace_ops. The mutex is taken within checking the ftrace_ops flag that
states it was initializied but the flag is checked again after the mutex
has been taken. Checking first outside the mutex allows it to shortcut
having to take the mutex. But then the check needs to be done again after
the mute is taken in case of races.

Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260902095501.6b59af20@gandalf.local.home
Fixes: f04f24fb7e48d ("ftrace, kprobes: Fix a deadlock on ftrace_regex_lock")
Reported-by: sashiko-bot@kernel.org
Close: https://lore.kernel.org/all/20260829025528.49A831F000E9@smtp.kernel.org/
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 283 insertions, 0 deletions

diff --git a/security/selinux/netif.c b/security/selinux/netif.c
new file mode 100644
index 000000000..fa6d24a37
--- /dev/null
+++ b/security/selinux/netif.c
@@ -0,0 +1,283 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * 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>
+ * Copyright (C) 2007 Hewlett-Packard Development Company, L.P.
+ *		      Paul Moore <paul@paul-moore.com>
+ */
+#include <linux/init.h>
+#include <linux/types.h>
+#include <linux/slab.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 <net/net_namespace.h>
+
+#include "initcalls.h"
+#include "security.h"
+#include "objsec.h"
+#include "netif.h"
+
+#define SEL_NETIF_HASH_SIZE	64
+#define SEL_NETIF_HASH_MAX	1024
+
+struct sel_netif {
+	struct list_head list;
+	struct netif_security_struct nsec;
+	struct rcu_head rcu_head;
+};
+
+static u32 sel_netif_total;
+static DEFINE_SPINLOCK(sel_netif_lock);
+static struct list_head sel_netif_hash[SEL_NETIF_HASH_SIZE];
+
+/**
+ * sel_netif_hashfn - Hashing function for the interface table
+ * @ns: the network namespace
+ * @ifindex: the network interface
+ *
+ * Description:
+ * This is the hashing function for the network interface table, it returns the
+ * bucket number for the given interface.
+ *
+ */
+static inline u32 sel_netif_hashfn(const struct net *ns, int ifindex)
+{
+	return (((uintptr_t)ns + ifindex) & (SEL_NETIF_HASH_SIZE - 1));
+}
+
+/**
+ * sel_netif_find - Search for an interface record
+ * @ns: the network namespace
+ * @ifindex: the network interface
+ *
+ * Description:
+ * Search the network interface table and return the record matching @ifindex.
+ * If an entry can not be found in the table return NULL.
+ *
+ */
+static inline struct sel_netif *sel_netif_find(const struct net *ns,
+					       int ifindex)
+{
+	u32 idx = sel_netif_hashfn(ns, ifindex);
+	struct sel_netif *netif;
+
+	list_for_each_entry_rcu(netif, &sel_netif_hash[idx], list)
+		if (net_eq(netif->nsec.ns, ns) &&
+		    netif->nsec.ifindex == ifindex)
+			return netif;
+
+	return NULL;
+}
+
+/**
+ * sel_netif_insert - Insert a new interface into the table
+ * @netif: the new interface record
+ *
+ * Description:
+ * Add a new interface record to the network interface hash table.  Returns
+ * zero on success, negative values on failure.
+ *
+ */
+static int sel_netif_insert(struct sel_netif *netif)
+{
+	u32 idx;
+
+	if (sel_netif_total >= SEL_NETIF_HASH_MAX)
+		return -ENOSPC;
+
+	idx = sel_netif_hashfn(netif->nsec.ns, netif->nsec.ifindex);
+	list_add_rcu(&netif->list, &sel_netif_hash[idx]);
+	sel_netif_total++;
+
+	return 0;
+}
+
+/**
+ * sel_netif_destroy - Remove an interface record from the table
+ * @netif: the existing interface record
+ *
+ * Description:
+ * Remove an existing interface record from the network interface table.
+ *
+ */
+static void sel_netif_destroy(struct sel_netif *netif)
+{
+	list_del_rcu(&netif->list);
+	sel_netif_total--;
+	kfree_rcu(netif, rcu_head);
+}
+
+/**
+ * sel_netif_sid_slow - Lookup the SID of a network interface using the policy
+ * @ns: the network namespace
+ * @ifindex: the network interface
+ * @sid: interface SID
+ *
+ * Description:
+ * This function determines the SID of a network interface by querying the
+ * security policy.  The result is added to the network interface table to
+ * speedup future queries.  Returns zero on success, negative values on
+ * failure.
+ *
+ */
+static int sel_netif_sid_slow(struct net *ns, int ifindex, u32 *sid)
+{
+	int ret = 0;
+	struct sel_netif *netif;
+	struct sel_netif *new;
+	struct net_device *dev;
+
+	/* NOTE: we always use init's network namespace since we don't
+	 * currently support containers */
+
+	dev = dev_get_by_index(ns, ifindex);
+	if (unlikely(dev == NULL)) {
+		pr_warn("SELinux: failure in %s(), invalid network interface (%d)\n",
+			__func__, ifindex);
+		return -ENOENT;
+	}
+
+	spin_lock_bh(&sel_netif_lock);
+	netif = sel_netif_find(ns, ifindex);
+	if (netif != NULL) {
+		*sid = netif->nsec.sid;
+		goto out;
+	}
+
+	ret = security_netif_sid(dev->name, sid);
+	if (ret != 0)
+		goto out;
+
+	/* If this memory allocation fails still return 0. The SID
+	 * is valid, it just won't be added to the cache.
+	 */
+	new = kmalloc_obj(*new, GFP_ATOMIC);
+	if (new) {
+		new->nsec.ns = ns;
+		new->nsec.ifindex = ifindex;
+		new->nsec.sid = *sid;
+		if (sel_netif_insert(new))
+			kfree(new);
+	}
+
+out:
+	spin_unlock_bh(&sel_netif_lock);
+	dev_put(dev);
+	if (unlikely(ret))
+		pr_warn("SELinux: failure in %s(), unable to determine network interface label (%d)\n",
+			__func__, ifindex);
+	return ret;
+}
+
+/**
+ * sel_netif_sid - Lookup the SID of a network interface
+ * @ns: the network namespace
+ * @ifindex: the network interface
+ * @sid: interface SID
+ *
+ * Description:
+ * This function determines the SID of a network interface using the fastest
+ * method possible.  First the interface table is queried, but if an entry
+ * can't be found then the policy is queried and the result is added to the
+ * table to speedup future queries.  Returns zero on success, negative values
+ * on failure.
+ *
+ */
+int sel_netif_sid(struct net *ns, int ifindex, u32 *sid)
+{
+	struct sel_netif *netif;
+
+	rcu_read_lock();
+	netif = sel_netif_find(ns, ifindex);
+	if (likely(netif != NULL)) {
+		*sid = netif->nsec.sid;
+		rcu_read_unlock();
+		return 0;
+	}
+	rcu_read_unlock();
+
+	return sel_netif_sid_slow(ns, ifindex, sid);
+}
+
+/**
+ * sel_netif_kill - Remove an entry from the network interface table
+ * @ns: the network namespace
+ * @ifindex: the network interface
+ *
+ * Description:
+ * This function removes the entry matching @ifindex from the network interface
+ * table if it exists.
+ *
+ */
+static void sel_netif_kill(const struct net *ns, int ifindex)
+{
+	struct sel_netif *netif;
+
+	rcu_read_lock();
+	spin_lock_bh(&sel_netif_lock);
+	netif = sel_netif_find(ns, ifindex);
+	if (netif)
+		sel_netif_destroy(netif);
+	spin_unlock_bh(&sel_netif_lock);
+	rcu_read_unlock();
+}
+
+/**
+ * sel_netif_flush - Flush the entire network interface table
+ *
+ * Description:
+ * Remove all entries from the network interface table.
+ *
+ */
+void sel_netif_flush(void)
+{
+	int idx;
+	struct sel_netif *netif;
+
+	spin_lock_bh(&sel_netif_lock);
+	for (idx = 0; idx < SEL_NETIF_HASH_SIZE; idx++)
+		list_for_each_entry(netif, &sel_netif_hash[idx], list)
+			sel_netif_destroy(netif);
+	spin_unlock_bh(&sel_netif_lock);
+}
+
+static int sel_netif_netdev_notifier_handler(struct notifier_block *this,
+					     unsigned long event, void *ptr)
+{
+	struct net_device *dev = netdev_notifier_info_to_dev(ptr);
+
+	if (event == NETDEV_DOWN)
+		sel_netif_kill(dev_net(dev), dev->ifindex);
+
+	return NOTIFY_DONE;
+}
+
+static struct notifier_block sel_netif_netdev_notifier = {
+	.notifier_call = sel_netif_netdev_notifier_handler,
+};
+
+int __init sel_netif_init(void)
+{
+	int i;
+
+	if (!selinux_enabled_boot)
+		return 0;
+
+	for (i = 0; i < SEL_NETIF_HASH_SIZE; i++)
+		INIT_LIST_HEAD(&sel_netif_hash[i]);
+
+	register_netdevice_notifier(&sel_netif_netdev_notifier);
+
+	return 0;
+}
+