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, 284 insertions, 0 deletions

diff --git a/net/sched/act_connmark.c b/net/sched/act_connmark.c
new file mode 100644
index 000000000..c634af5ed
--- /dev/null
+++ b/net/sched/act_connmark.c
@@ -0,0 +1,284 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * net/sched/act_connmark.c  netfilter connmark retriever action
+ * skb mark is over-written
+ *
+ * Copyright (c) 2011 Felix Fietkau <nbd@openwrt.org>
+*/
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/skbuff.h>
+#include <linux/rtnetlink.h>
+#include <linux/pkt_cls.h>
+#include <linux/ip.h>
+#include <linux/ipv6.h>
+#include <net/netlink.h>
+#include <net/pkt_sched.h>
+#include <net/act_api.h>
+#include <net/pkt_cls.h>
+#include <uapi/linux/tc_act/tc_connmark.h>
+#include <net/tc_act/tc_connmark.h>
+#include <net/tc_wrapper.h>
+
+#include <net/netfilter/nf_conntrack.h>
+#include <net/netfilter/nf_conntrack_core.h>
+#include <net/netfilter/nf_conntrack_zones.h>
+
+static struct tc_action_ops act_connmark_ops;
+
+TC_INDIRECT_SCOPE int tcf_connmark_act(struct sk_buff *skb,
+				       const struct tc_action *a,
+				       struct tcf_result *res)
+{
+	const struct nf_conntrack_tuple_hash *thash;
+	struct nf_conntrack_tuple tuple;
+	enum ip_conntrack_info ctinfo;
+	struct tcf_connmark_info *ca = to_connmark(a);
+	struct tcf_connmark_parms *parms;
+	struct nf_conntrack_zone zone;
+	struct nf_conn *c;
+	int proto;
+
+	tcf_lastuse_update(&ca->tcf_tm);
+	tcf_action_update_bstats(&ca->common, skb);
+
+	parms = rcu_dereference_bh(ca->parms);
+
+	switch (skb_protocol(skb, true)) {
+	case htons(ETH_P_IP):
+		if (skb->len < sizeof(struct iphdr))
+			goto out;
+
+		proto = NFPROTO_IPV4;
+		break;
+	case htons(ETH_P_IPV6):
+		if (skb->len < sizeof(struct ipv6hdr))
+			goto out;
+
+		proto = NFPROTO_IPV6;
+		break;
+	default:
+		goto out;
+	}
+
+	c = nf_ct_get(skb, &ctinfo);
+	if (c) {
+		skb->mark = READ_ONCE(c->mark);
+		goto count;
+	}
+
+	if (!nf_ct_get_tuplepr(skb, skb_network_offset(skb), proto, parms->net,
+			       &tuple))
+		goto out;
+
+	zone.id = parms->zone;
+	zone.dir = NF_CT_DEFAULT_ZONE_DIR;
+
+	thash = nf_conntrack_find_get(parms->net, &zone, &tuple);
+	if (!thash)
+		goto out;
+
+	c = nf_ct_tuplehash_to_ctrack(thash);
+	skb->mark = READ_ONCE(c->mark);
+	nf_ct_put(c);
+
+count:
+	/* using overlimits stats to count how many packets marked */
+	tcf_action_inc_overlimit_qstats(&ca->common);
+out:
+	return parms->action;
+}
+
+static const struct nla_policy connmark_policy[TCA_CONNMARK_MAX + 1] = {
+	[TCA_CONNMARK_PARMS] = { .len = sizeof(struct tc_connmark) },
+};
+
+static int tcf_connmark_init(struct net *net, struct nlattr *nla,
+			     struct nlattr *est, struct tc_action **a,
+			     struct tcf_proto *tp, u32 flags,
+			     struct netlink_ext_ack *extack)
+{
+	struct tc_action_net *tn = net_generic(net, act_connmark_ops.net_id);
+	struct tcf_connmark_parms *nparms, *oparms;
+	struct nlattr *tb[TCA_CONNMARK_MAX + 1];
+	bool bind = flags & TCA_ACT_FLAGS_BIND;
+	struct tcf_chain *goto_ch = NULL;
+	struct tcf_connmark_info *ci;
+	struct tc_connmark *parm;
+	int ret = 0, err;
+	u32 index;
+
+	if (!nla)
+		return -EINVAL;
+
+	ret = nla_parse_nested_deprecated(tb, TCA_CONNMARK_MAX, nla,
+					  connmark_policy, NULL);
+	if (ret < 0)
+		return ret;
+
+	if (!tb[TCA_CONNMARK_PARMS])
+		return -EINVAL;
+
+	nparms = kzalloc_obj(*nparms);
+	if (!nparms)
+		return -ENOMEM;
+
+	parm = nla_data(tb[TCA_CONNMARK_PARMS]);
+	index = parm->index;
+	ret = tcf_idr_check_alloc(tn, &index, a, bind);
+	if (!ret) {
+		ret = tcf_idr_create_from_flags(tn, index, est, a,
+						&act_connmark_ops, bind, flags);
+		if (ret) {
+			tcf_idr_cleanup(tn, index);
+			err = ret;
+			goto out_free;
+		}
+
+		ci = to_connmark(*a);
+
+		nparms->net = net;
+		nparms->zone = parm->zone;
+
+		ret = ACT_P_CREATED;
+	} else if (ret > 0) {
+		ci = to_connmark(*a);
+		if (bind) {
+			err = ACT_P_BOUND;
+			goto out_free;
+		}
+		if (!(flags & TCA_ACT_FLAGS_REPLACE)) {
+			err = -EEXIST;
+			goto release_idr;
+		}
+
+		nparms->net = rtnl_dereference(ci->parms)->net;
+		nparms->zone = parm->zone;
+
+		ret = 0;
+	} else {
+		err = ret;
+		goto out_free;
+	}
+
+	err = tcf_action_check_ctrlact(parm->action, tp, &goto_ch, extack);
+	if (err < 0)
+		goto release_idr;
+
+	nparms->action = parm->action;
+
+	spin_lock_bh(&ci->tcf_lock);
+	goto_ch = tcf_action_set_ctrlact(*a, parm->action, goto_ch);
+	oparms = rcu_replace_pointer(ci->parms, nparms, lockdep_is_held(&ci->tcf_lock));
+	spin_unlock_bh(&ci->tcf_lock);
+
+	if (goto_ch)
+		tcf_chain_put_by_act(goto_ch);
+
+	if (oparms)
+		kfree_rcu(oparms, rcu);
+
+	return ret;
+
+release_idr:
+	tcf_idr_release(*a, bind);
+out_free:
+	kfree(nparms);
+	return err;
+}
+
+static inline int tcf_connmark_dump(struct sk_buff *skb, struct tc_action *a,
+				    int bind, int ref)
+{
+	const struct tcf_connmark_info *ci = to_connmark(a);
+	unsigned char *b = skb_tail_pointer(skb);
+	const struct tcf_connmark_parms *parms;
+	struct tc_connmark opt;
+	struct tcf_t t;
+
+	memset(&opt, 0, sizeof(opt));
+
+	opt.index   = ci->tcf_index;
+	opt.refcnt  = refcount_read(&ci->tcf_refcnt) - ref;
+	opt.bindcnt = atomic_read(&ci->tcf_bindcnt) - bind;
+
+	rcu_read_lock();
+	parms = rcu_dereference(ci->parms);
+
+	opt.action = parms->action;
+	opt.zone = parms->zone;
+	if (nla_put(skb, TCA_CONNMARK_PARMS, sizeof(opt), &opt))
+		goto nla_put_failure;
+
+	tcf_tm_dump(&t, &ci->tcf_tm);
+	if (nla_put_64bit(skb, TCA_CONNMARK_TM, sizeof(t), &t,
+			  TCA_CONNMARK_PAD))
+		goto nla_put_failure;
+	rcu_read_unlock();
+
+	return skb->len;
+
+nla_put_failure:
+	rcu_read_unlock();
+	nlmsg_trim(skb, b);
+	return -1;
+}
+
+static void tcf_connmark_cleanup(struct tc_action *a)
+{
+	struct tcf_connmark_info *ci = to_connmark(a);
+	struct tcf_connmark_parms *parms;
+
+	parms = rcu_dereference_protected(ci->parms, 1);
+	if (parms)
+		kfree_rcu(parms, rcu);
+}
+
+static struct tc_action_ops act_connmark_ops = {
+	.kind		=	"connmark",
+	.id		=	TCA_ID_CONNMARK,
+	.owner		=	THIS_MODULE,
+	.act		=	tcf_connmark_act,
+	.dump		=	tcf_connmark_dump,
+	.init		=	tcf_connmark_init,
+	.cleanup	=	tcf_connmark_cleanup,
+	.size		=	sizeof(struct tcf_connmark_info),
+};
+MODULE_ALIAS_NET_ACT("connmark");
+
+static __net_init int connmark_init_net(struct net *net)
+{
+	struct tc_action_net *tn = net_generic(net, act_connmark_ops.net_id);
+
+	return tc_action_net_init(net, tn, &act_connmark_ops);
+}
+
+static void __net_exit connmark_exit_net(struct list_head *net_list)
+{
+	tc_action_net_exit(net_list, act_connmark_ops.net_id);
+}
+
+static struct pernet_operations connmark_net_ops = {
+	.init = connmark_init_net,
+	.exit_batch = connmark_exit_net,
+	.id   = &act_connmark_ops.net_id,
+	.size = sizeof(struct tc_action_net),
+};
+
+static int __init connmark_init_module(void)
+{
+	return tcf_register_action(&act_connmark_ops, &connmark_net_ops);
+}
+
+static void __exit connmark_cleanup_module(void)
+{
+	tcf_unregister_action(&act_connmark_ops, &connmark_net_ops);
+}
+
+module_init(connmark_init_module);
+module_exit(connmark_cleanup_module);
+MODULE_AUTHOR("Felix Fietkau <nbd@openwrt.org>");
+MODULE_DESCRIPTION("Connection tracking mark restoring");
+MODULE_LICENSE("GPL");