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, 387 insertions, 0 deletions

diff --git a/net/kcm/kcmproc.c b/net/kcm/kcmproc.c
new file mode 100644
index 000000000..25c1007f1
--- /dev/null
+++ b/net/kcm/kcmproc.c
@@ -0,0 +1,387 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/in.h>
+#include <linux/inet.h>
+#include <linux/list.h>
+#include <linux/module.h>
+#include <linux/net.h>
+#include <linux/proc_fs.h>
+#include <linux/rculist.h>
+#include <linux/seq_file.h>
+#include <linux/socket.h>
+#include <net/inet_sock.h>
+#include <net/kcm.h>
+#include <net/net_namespace.h>
+#include <net/netns/generic.h>
+#include <net/tcp.h>
+
+#ifdef CONFIG_PROC_FS
+static struct kcm_mux *kcm_get_first(struct seq_file *seq)
+{
+	struct net *net = seq_file_net(seq);
+	struct kcm_net *knet = net_generic(net, kcm_net_id);
+
+	return list_first_or_null_rcu(&knet->mux_list,
+				      struct kcm_mux, kcm_mux_list);
+}
+
+static struct kcm_mux *kcm_get_next(struct kcm_mux *mux)
+{
+	struct kcm_net *knet = mux->knet;
+
+	return list_next_or_null_rcu(&knet->mux_list, &mux->kcm_mux_list,
+				     struct kcm_mux, kcm_mux_list);
+}
+
+static struct kcm_mux *kcm_get_idx(struct seq_file *seq, loff_t pos)
+{
+	struct net *net = seq_file_net(seq);
+	struct kcm_net *knet = net_generic(net, kcm_net_id);
+	struct kcm_mux *m;
+
+	list_for_each_entry_rcu(m, &knet->mux_list, kcm_mux_list) {
+		if (!pos)
+			return m;
+		--pos;
+	}
+	return NULL;
+}
+
+static void *kcm_seq_next(struct seq_file *seq, void *v, loff_t *pos)
+{
+	void *p;
+
+	if (v == SEQ_START_TOKEN)
+		p = kcm_get_first(seq);
+	else
+		p = kcm_get_next(v);
+	++*pos;
+	return p;
+}
+
+static void *kcm_seq_start(struct seq_file *seq, loff_t *pos)
+	__acquires(rcu)
+{
+	rcu_read_lock();
+
+	if (!*pos)
+		return SEQ_START_TOKEN;
+	else
+		return kcm_get_idx(seq, *pos - 1);
+}
+
+static void kcm_seq_stop(struct seq_file *seq, void *v)
+	__releases(rcu)
+{
+	rcu_read_unlock();
+}
+
+struct kcm_proc_mux_state {
+	struct seq_net_private p;
+	int idx;
+};
+
+static void kcm_format_mux_header(struct seq_file *seq)
+{
+	struct net *net = seq_file_net(seq);
+	struct kcm_net *knet = net_generic(net, kcm_net_id);
+
+	seq_printf(seq,
+		   "*** KCM statistics (%d MUX) ****\n",
+		   knet->count);
+
+	seq_printf(seq,
+		   "%-14s %-10s %-16s %-10s %-16s %-8s %-8s %-8s %-8s %s",
+		   "Object",
+		   "RX-Msgs",
+		   "RX-Bytes",
+		   "TX-Msgs",
+		   "TX-Bytes",
+		   "Recv-Q",
+		   "Rmem",
+		   "Send-Q",
+		   "Smem",
+		   "Status");
+
+	/* XXX: pdsts header stuff here */
+	seq_puts(seq, "\n");
+}
+
+static void kcm_format_sock(struct kcm_sock *kcm, struct seq_file *seq,
+			    int i, int *len)
+{
+	seq_printf(seq,
+		   "   kcm-%-7u %-10llu %-16llu %-10llu %-16llu %-8d %-8d %-8d %-8s ",
+		   kcm->index,
+		   kcm->stats.rx_msgs,
+		   kcm->stats.rx_bytes,
+		   kcm->stats.tx_msgs,
+		   kcm->stats.tx_bytes,
+		   kcm->sk.sk_receive_queue.qlen,
+		   sk_rmem_alloc_get(&kcm->sk),
+		   kcm->sk.sk_write_queue.qlen,
+		   "-");
+
+	if (kcm->tx_psock)
+		seq_printf(seq, "Psck-%u ", kcm->tx_psock->index);
+
+	if (kcm->tx_wait)
+		seq_puts(seq, "TxWait ");
+
+	if (kcm->tx_wait_more)
+		seq_puts(seq, "WMore ");
+
+	if (kcm->rx_wait)
+		seq_puts(seq, "RxWait ");
+
+	seq_puts(seq, "\n");
+}
+
+static void kcm_format_psock(struct kcm_psock *psock, struct seq_file *seq,
+			     int i, int *len)
+{
+	seq_printf(seq,
+		   "   psock-%-5u %-10llu %-16llu %-10llu %-16llu %-8d %-8d %-8d %-8d ",
+		   psock->index,
+		   psock->strp.stats.msgs,
+		   psock->strp.stats.bytes,
+		   psock->stats.tx_msgs,
+		   psock->stats.tx_bytes,
+		   psock->sk->sk_receive_queue.qlen,
+		   atomic_read(&psock->sk->sk_rmem_alloc),
+		   psock->sk->sk_write_queue.qlen,
+		   refcount_read(&psock->sk->sk_wmem_alloc));
+
+	if (psock->done)
+		seq_puts(seq, "Done ");
+
+	if (psock->tx_stopped)
+		seq_puts(seq, "TxStop ");
+
+	if (psock->strp.stopped)
+		seq_puts(seq, "RxStop ");
+
+	if (psock->tx_kcm)
+		seq_printf(seq, "Rsvd-%d ", psock->tx_kcm->index);
+
+	if (!psock->strp.paused && !psock->ready_rx_msg) {
+		if (psock->sk->sk_receive_queue.qlen) {
+			if (psock->strp.need_bytes)
+				seq_printf(seq, "RxWait=%u ",
+					   psock->strp.need_bytes);
+			else
+				seq_printf(seq, "RxWait ");
+		}
+	} else  {
+		if (psock->strp.paused)
+			seq_puts(seq, "RxPause ");
+
+		if (psock->ready_rx_msg)
+			seq_puts(seq, "RdyRx ");
+	}
+
+	seq_puts(seq, "\n");
+}
+
+static void
+kcm_format_mux(struct kcm_mux *mux, loff_t idx, struct seq_file *seq)
+{
+	int i, len;
+	struct kcm_sock *kcm;
+	struct kcm_psock *psock;
+
+	/* mux information */
+	seq_printf(seq,
+		   "%-6s%-8s %-10llu %-16llu %-10llu %-16llu %-8s %-8s %-8s %-8s ",
+		   "mux", "",
+		   mux->stats.rx_msgs,
+		   mux->stats.rx_bytes,
+		   mux->stats.tx_msgs,
+		   mux->stats.tx_bytes,
+		   "-", "-", "-", "-");
+
+	seq_printf(seq, "KCMs: %d, Psocks %d\n",
+		   mux->kcm_socks_cnt, mux->psocks_cnt);
+
+	/* kcm sock information */
+	i = 0;
+	spin_lock_bh(&mux->lock);
+	list_for_each_entry(kcm, &mux->kcm_socks, kcm_sock_list) {
+		kcm_format_sock(kcm, seq, i, &len);
+		i++;
+	}
+	i = 0;
+	list_for_each_entry(psock, &mux->psocks, psock_list) {
+		kcm_format_psock(psock, seq, i, &len);
+		i++;
+	}
+	spin_unlock_bh(&mux->lock);
+}
+
+static int kcm_seq_show(struct seq_file *seq, void *v)
+{
+	struct kcm_proc_mux_state *mux_state;
+
+	mux_state = seq->private;
+	if (v == SEQ_START_TOKEN) {
+		mux_state->idx = 0;
+		kcm_format_mux_header(seq);
+	} else {
+		kcm_format_mux(v, mux_state->idx, seq);
+		mux_state->idx++;
+	}
+	return 0;
+}
+
+static const struct seq_operations kcm_seq_ops = {
+	.show	= kcm_seq_show,
+	.start	= kcm_seq_start,
+	.next	= kcm_seq_next,
+	.stop	= kcm_seq_stop,
+};
+
+static int kcm_stats_seq_show(struct seq_file *seq, void *v)
+{
+	struct kcm_psock_stats psock_stats;
+	struct kcm_mux_stats mux_stats;
+	struct strp_aggr_stats strp_stats;
+	struct kcm_mux *mux;
+	struct kcm_psock *psock;
+	struct net *net = seq->private;
+	struct kcm_net *knet = net_generic(net, kcm_net_id);
+
+	memset(&mux_stats, 0, sizeof(mux_stats));
+	memset(&psock_stats, 0, sizeof(psock_stats));
+	memset(&strp_stats, 0, sizeof(strp_stats));
+
+	mutex_lock(&knet->mutex);
+
+	aggregate_mux_stats(&knet->aggregate_mux_stats, &mux_stats);
+	aggregate_psock_stats(&knet->aggregate_psock_stats,
+			      &psock_stats);
+	aggregate_strp_stats(&knet->aggregate_strp_stats,
+			     &strp_stats);
+
+	list_for_each_entry(mux, &knet->mux_list, kcm_mux_list) {
+		spin_lock_bh(&mux->lock);
+		aggregate_mux_stats(&mux->stats, &mux_stats);
+		aggregate_psock_stats(&mux->aggregate_psock_stats,
+				      &psock_stats);
+		aggregate_strp_stats(&mux->aggregate_strp_stats,
+				     &strp_stats);
+		list_for_each_entry(psock, &mux->psocks, psock_list) {
+			aggregate_psock_stats(&psock->stats, &psock_stats);
+			save_strp_stats(&psock->strp, &strp_stats);
+		}
+
+		spin_unlock_bh(&mux->lock);
+	}
+
+	mutex_unlock(&knet->mutex);
+
+	seq_printf(seq,
+		   "%-8s %-10s %-16s %-10s %-16s %-10s %-10s %-10s %-10s %-10s\n",
+		   "MUX",
+		   "RX-Msgs",
+		   "RX-Bytes",
+		   "TX-Msgs",
+		   "TX-Bytes",
+		   "TX-Retries",
+		   "Attach",
+		   "Unattach",
+		   "UnattchRsvd",
+		   "RX-RdyDrops");
+
+	seq_printf(seq,
+		   "%-8s %-10llu %-16llu %-10llu %-16llu %-10u %-10u %-10u %-10u %-10u\n",
+		   "",
+		   mux_stats.rx_msgs,
+		   mux_stats.rx_bytes,
+		   mux_stats.tx_msgs,
+		   mux_stats.tx_bytes,
+		   mux_stats.tx_retries,
+		   mux_stats.psock_attach,
+		   mux_stats.psock_unattach_rsvd,
+		   mux_stats.psock_unattach,
+		   mux_stats.rx_ready_drops);
+
+	seq_printf(seq,
+		   "%-8s %-10s %-16s %-10s %-16s %-10s %-10s %-10s %-10s %-10s %-10s %-10s %-10s %-10s %-10s %-10s\n",
+		   "Psock",
+		   "RX-Msgs",
+		   "RX-Bytes",
+		   "TX-Msgs",
+		   "TX-Bytes",
+		   "Reserved",
+		   "Unreserved",
+		   "RX-Aborts",
+		   "RX-Intr",
+		   "RX-Unrecov",
+		   "RX-MemFail",
+		   "RX-NeedMor",
+		   "RX-BadLen",
+		   "RX-TooBig",
+		   "RX-Timeout",
+		   "TX-Aborts");
+
+	seq_printf(seq,
+		   "%-8s %-10llu %-16llu %-10llu %-16llu %-10llu %-10llu %-10u %-10u %-10u %-10u %-10u %-10u %-10u %-10u %-10u\n",
+		   "",
+		   strp_stats.msgs,
+		   strp_stats.bytes,
+		   psock_stats.tx_msgs,
+		   psock_stats.tx_bytes,
+		   psock_stats.reserved,
+		   psock_stats.unreserved,
+		   strp_stats.aborts,
+		   strp_stats.interrupted,
+		   strp_stats.unrecov_intr,
+		   strp_stats.mem_fail,
+		   strp_stats.need_more_hdr,
+		   strp_stats.bad_hdr_len,
+		   strp_stats.msg_too_big,
+		   strp_stats.msg_timeouts,
+		   psock_stats.tx_aborts);
+
+	return 0;
+}
+
+static int kcm_proc_init_net(struct net *net)
+{
+	if (!proc_create_net_single("kcm_stats", 0444, net->proc_net,
+			 kcm_stats_seq_show, NULL))
+		goto out_kcm_stats;
+
+	if (!proc_create_net("kcm", 0444, net->proc_net, &kcm_seq_ops,
+			sizeof(struct kcm_proc_mux_state)))
+		goto out_kcm;
+
+	return 0;
+
+out_kcm:
+	remove_proc_entry("kcm_stats", net->proc_net);
+out_kcm_stats:
+	return -ENOMEM;
+}
+
+static void kcm_proc_exit_net(struct net *net)
+{
+	remove_proc_entry("kcm", net->proc_net);
+	remove_proc_entry("kcm_stats", net->proc_net);
+}
+
+static struct pernet_operations kcm_net_ops = {
+	.init = kcm_proc_init_net,
+	.exit = kcm_proc_exit_net,
+};
+
+int __init kcm_proc_init(void)
+{
+	return register_pernet_subsys(&kcm_net_ops);
+}
+
+void __exit kcm_proc_exit(void)
+{
+	unregister_pernet_subsys(&kcm_net_ops);
+}
+
+#endif /* CONFIG_PROC_FS */