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, 267 insertions, 0 deletions

diff --git a/net/packet/diag.c b/net/packet/diag.c
new file mode 100644
index 000000000..cee773f46
--- /dev/null
+++ b/net/packet/diag.c
@@ -0,0 +1,267 @@
+// SPDX-License-Identifier: GPL-2.0-only
+#include <linux/module.h>
+#include <linux/sock_diag.h>
+#include <linux/net.h>
+#include <linux/netdevice.h>
+#include <linux/packet_diag.h>
+#include <linux/percpu.h>
+#include <net/net_namespace.h>
+#include <net/sock.h>
+
+#include "internal.h"
+
+static int pdiag_put_info(const struct packet_sock *po, struct sk_buff *nlskb)
+{
+	struct packet_diag_info pinfo;
+
+	pinfo.pdi_index = po->ifindex;
+	pinfo.pdi_version = po->tp_version;
+	pinfo.pdi_reserve = po->tp_reserve;
+	pinfo.pdi_copy_thresh = READ_ONCE(po->copy_thresh);
+	pinfo.pdi_tstamp = READ_ONCE(po->tp_tstamp);
+
+	pinfo.pdi_flags = 0;
+	if (packet_sock_flag(po, PACKET_SOCK_RUNNING))
+		pinfo.pdi_flags |= PDI_RUNNING;
+	if (packet_sock_flag(po, PACKET_SOCK_AUXDATA))
+		pinfo.pdi_flags |= PDI_AUXDATA;
+	if (packet_sock_flag(po, PACKET_SOCK_ORIGDEV))
+		pinfo.pdi_flags |= PDI_ORIGDEV;
+	if (READ_ONCE(po->vnet_hdr_sz))
+		pinfo.pdi_flags |= PDI_VNETHDR;
+	if (packet_sock_flag(po, PACKET_SOCK_TP_LOSS))
+		pinfo.pdi_flags |= PDI_LOSS;
+
+	return nla_put(nlskb, PACKET_DIAG_INFO, sizeof(pinfo), &pinfo);
+}
+
+static int pdiag_put_mclist(const struct packet_sock *po, struct sk_buff *nlskb)
+{
+	struct nlattr *mca;
+	struct packet_mclist *ml;
+
+	mca = nla_nest_start_noflag(nlskb, PACKET_DIAG_MCLIST);
+	if (!mca)
+		return -EMSGSIZE;
+
+	rtnl_lock();
+	for (ml = po->mclist; ml; ml = ml->next) {
+		struct packet_diag_mclist *dml;
+
+		dml = nla_reserve_nohdr(nlskb, sizeof(*dml));
+		if (!dml) {
+			rtnl_unlock();
+			nla_nest_cancel(nlskb, mca);
+			return -EMSGSIZE;
+		}
+
+		dml->pdmc_index = ml->ifindex;
+		dml->pdmc_type = ml->type;
+		dml->pdmc_alen = ml->alen;
+		dml->pdmc_count = ml->count;
+		BUILD_BUG_ON(sizeof(dml->pdmc_addr) != sizeof(ml->addr));
+		memcpy(dml->pdmc_addr, ml->addr, sizeof(ml->addr));
+	}
+
+	rtnl_unlock();
+	nla_nest_end(nlskb, mca);
+
+	return 0;
+}
+
+static int pdiag_put_ring(struct packet_ring_buffer *ring, int ver, int nl_type,
+		struct sk_buff *nlskb)
+{
+	struct packet_diag_ring pdr;
+
+	if (!ring->pg_vec)
+		return 0;
+
+	pdr.pdr_block_size = ring->pg_vec_pages << PAGE_SHIFT;
+	pdr.pdr_block_nr = ring->pg_vec_len;
+	pdr.pdr_frame_size = ring->frame_size;
+	pdr.pdr_frame_nr = ring->frame_max + 1;
+
+	if (ver > TPACKET_V2) {
+		pdr.pdr_retire_tmo = ktime_to_ms(ring->prb_bdqc.interval_ktime);
+		pdr.pdr_sizeof_priv = ring->prb_bdqc.blk_sizeof_priv;
+		pdr.pdr_features = ring->prb_bdqc.feature_req_word;
+	} else {
+		pdr.pdr_retire_tmo = 0;
+		pdr.pdr_sizeof_priv = 0;
+		pdr.pdr_features = 0;
+	}
+
+	return nla_put(nlskb, nl_type, sizeof(pdr), &pdr);
+}
+
+static int pdiag_put_rings_cfg(struct packet_sock *po, struct sk_buff *skb)
+{
+	int ret;
+
+	mutex_lock(&po->pg_vec_lock);
+	ret = pdiag_put_ring(&po->rx_ring, po->tp_version,
+			PACKET_DIAG_RX_RING, skb);
+	if (!ret)
+		ret = pdiag_put_ring(&po->tx_ring, po->tp_version,
+				PACKET_DIAG_TX_RING, skb);
+	mutex_unlock(&po->pg_vec_lock);
+
+	return ret;
+}
+
+static int pdiag_put_fanout(struct packet_sock *po, struct sk_buff *nlskb)
+{
+	int ret = 0;
+
+	mutex_lock(&fanout_mutex);
+	if (po->fanout) {
+		u32 val;
+
+		val = (u32)po->fanout->id | ((u32)po->fanout->type << 16);
+		ret = nla_put_u32(nlskb, PACKET_DIAG_FANOUT, val);
+	}
+	mutex_unlock(&fanout_mutex);
+
+	return ret;
+}
+
+static int sk_diag_fill(struct sock *sk, struct sk_buff *skb,
+			struct packet_diag_req *req,
+			bool may_report_filterinfo,
+			struct user_namespace *user_ns,
+			u32 portid, u32 seq, u32 flags, u64 sk_ino)
+{
+	struct nlmsghdr *nlh;
+	struct packet_diag_msg *rp;
+	struct packet_sock *po = pkt_sk(sk);
+
+	nlh = nlmsg_put(skb, portid, seq, SOCK_DIAG_BY_FAMILY, sizeof(*rp), flags);
+	if (!nlh)
+		return -EMSGSIZE;
+
+	rp = nlmsg_data(nlh);
+	rp->pdiag_family = AF_PACKET;
+	rp->pdiag_type = sk->sk_type;
+	rp->pdiag_num = ntohs(READ_ONCE(po->num));
+	rp->pdiag_ino = sk_ino;
+	sock_diag_save_cookie(sk, rp->pdiag_cookie);
+
+	if ((req->pdiag_show & PACKET_SHOW_INFO) &&
+			pdiag_put_info(po, skb))
+		goto out_nlmsg_trim;
+
+	if ((req->pdiag_show & PACKET_SHOW_INFO) &&
+	    nla_put_u32(skb, PACKET_DIAG_UID,
+			from_kuid_munged(user_ns, sk_uid(sk))))
+		goto out_nlmsg_trim;
+
+	if ((req->pdiag_show & PACKET_SHOW_MCLIST) &&
+			pdiag_put_mclist(po, skb))
+		goto out_nlmsg_trim;
+
+	if ((req->pdiag_show & PACKET_SHOW_RING_CFG) &&
+			pdiag_put_rings_cfg(po, skb))
+		goto out_nlmsg_trim;
+
+	if ((req->pdiag_show & PACKET_SHOW_FANOUT) &&
+			pdiag_put_fanout(po, skb))
+		goto out_nlmsg_trim;
+
+	if ((req->pdiag_show & PACKET_SHOW_MEMINFO) &&
+	    sock_diag_put_meminfo(sk, skb, PACKET_DIAG_MEMINFO))
+		goto out_nlmsg_trim;
+
+	if ((req->pdiag_show & PACKET_SHOW_FILTER) &&
+	    sock_diag_put_filterinfo(may_report_filterinfo, sk, skb,
+				     PACKET_DIAG_FILTER))
+		goto out_nlmsg_trim;
+
+	nlmsg_end(skb, nlh);
+	return 0;
+
+out_nlmsg_trim:
+	nlmsg_cancel(skb, nlh);
+	return -EMSGSIZE;
+}
+
+static int packet_diag_dump(struct sk_buff *skb, struct netlink_callback *cb)
+{
+	int num = 0, s_num = cb->args[0];
+	struct packet_diag_req *req;
+	struct net *net;
+	struct sock *sk;
+	bool may_report_filterinfo;
+
+	net = sock_net(skb->sk);
+	req = nlmsg_data(cb->nlh);
+	may_report_filterinfo = netlink_net_capable(cb->skb, CAP_NET_ADMIN);
+
+	mutex_lock(&net->packet.sklist_lock);
+	sk_for_each(sk, &net->packet.sklist) {
+		if (!net_eq(sock_net(sk), net))
+			continue;
+		if (num < s_num)
+			goto next;
+
+		if (sk_diag_fill(sk, skb, req,
+				 may_report_filterinfo,
+				 sk_user_ns(NETLINK_CB(cb->skb).sk),
+				 NETLINK_CB(cb->skb).portid,
+				 cb->nlh->nlmsg_seq, NLM_F_MULTI,
+				 sock_i_ino(sk)) < 0)
+			goto done;
+next:
+		num++;
+	}
+done:
+	mutex_unlock(&net->packet.sklist_lock);
+	cb->args[0] = num;
+
+	return skb->len;
+}
+
+static int packet_diag_handler_dump(struct sk_buff *skb, struct nlmsghdr *h)
+{
+	int hdrlen = sizeof(struct packet_diag_req);
+	struct net *net = sock_net(skb->sk);
+	struct packet_diag_req *req;
+
+	if (nlmsg_len(h) < hdrlen)
+		return -EINVAL;
+
+	req = nlmsg_data(h);
+	/* Make it possible to support protocol filtering later */
+	if (req->sdiag_protocol)
+		return -EINVAL;
+
+	if (h->nlmsg_flags & NLM_F_DUMP) {
+		struct netlink_dump_control c = {
+			.dump = packet_diag_dump,
+		};
+		return netlink_dump_start(net->diag_nlsk, skb, h, &c);
+	} else
+		return -EOPNOTSUPP;
+}
+
+static const struct sock_diag_handler packet_diag_handler = {
+	.owner = THIS_MODULE,
+	.family = AF_PACKET,
+	.dump = packet_diag_handler_dump,
+};
+
+static int __init packet_diag_init(void)
+{
+	return sock_diag_register(&packet_diag_handler);
+}
+
+static void __exit packet_diag_exit(void)
+{
+	sock_diag_unregister(&packet_diag_handler);
+}
+
+module_init(packet_diag_init);
+module_exit(packet_diag_exit);
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("PACKET socket monitoring via SOCK_DIAG");
+MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_NETLINK, NETLINK_SOCK_DIAG, 17 /* AF_PACKET */);