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, 120 insertions, 0 deletions

diff --git a/security/selinux/netlink.c b/security/selinux/netlink.c
new file mode 100644
index 000000000..eb40e4603
--- /dev/null
+++ b/security/selinux/netlink.c
@@ -0,0 +1,120 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Netlink event notifications for SELinux.
+ *
+ * Author: James Morris <jmorris@redhat.com>
+ *
+ * Copyright (C) 2004 Red Hat, Inc., James Morris <jmorris@redhat.com>
+ */
+#include <linux/init.h>
+#include <linux/types.h>
+#include <linux/slab.h>
+#include <linux/stddef.h>
+#include <linux/kernel.h>
+#include <linux/export.h>
+#include <linux/skbuff.h>
+#include <linux/selinux_netlink.h>
+#include <net/net_namespace.h>
+#include <net/netlink.h>
+
+#include "initcalls.h"
+#include "security.h"
+
+static struct sock *selnl __ro_after_init;
+
+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;
+	sk_buff_data_t tmp;
+	struct sk_buff *skb;
+	struct nlmsghdr *nlh;
+
+	len = selnl_msglen(msgtype);
+
+	skb = nlmsg_new(len, GFP_USER);
+	if (!skb)
+		goto oom;
+
+	tmp = skb->tail;
+	nlh = nlmsg_put(skb, 0, 0, msgtype, len, 0);
+	if (!nlh)
+		goto out_kfree_skb;
+	selnl_add_payload(nlh, len, msgtype, data);
+	nlh->nlmsg_len = skb->tail - tmp;
+	NETLINK_CB(skb).dst_group = SELNLGRP_AVC;
+	netlink_broadcast(selnl, skb, 0, SELNLGRP_AVC, GFP_USER);
+out:
+	return;
+
+out_kfree_skb:
+	kfree_skb(skb);
+oom:
+	pr_err("SELinux:  OOM in %s\n", __func__);
+	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);
+}
+
+int __init sel_netlink_init(void)
+{
+	struct netlink_kernel_cfg cfg = {
+		.groups	= SELNLGRP_MAX,
+		.flags	= NL_CFG_F_NONROOT_RECV,
+	};
+
+	selnl = netlink_kernel_create(&init_net, NETLINK_SELINUX, &cfg);
+	if (selnl == NULL)
+		panic("SELinux:  Cannot create netlink socket.");
+	return 0;
+}