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, 304 insertions, 0 deletions

diff --git a/net/ipv6/ping.c b/net/ipv6/ping.c
new file mode 100644
index 000000000..6e90d0bf9
--- /dev/null
+++ b/net/ipv6/ping.c
@@ -0,0 +1,304 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * INET		An implementation of the TCP/IP protocol suite for the LINUX
+ *		operating system.  INET is implemented using the  BSD Socket
+ *		interface as the means of communication with the user level.
+ *
+ *		"Ping" sockets
+ *
+ * Based on ipv4/ping.c code.
+ *
+ * Authors:	Lorenzo Colitti (IPv6 support)
+ *		Vasiliy Kulikov / Openwall (IPv4 implementation, for Linux 2.6),
+ *		Pavel Kankovsky (IPv4 implementation, for Linux 2.4.32)
+ */
+
+#include <net/addrconf.h>
+#include <net/ipv6.h>
+#include <net/ip6_route.h>
+#include <net/protocol.h>
+#include <net/udp.h>
+#include <net/transp_v6.h>
+#include <linux/proc_fs.h>
+#include <linux/bpf-cgroup.h>
+#include <net/ping.h>
+
+/* Compatibility glue so we can support IPv6 when it's compiled as a module */
+static int dummy_ipv6_recv_error(struct sock *sk, struct msghdr *msg, int len)
+{
+	return -EAFNOSUPPORT;
+}
+static void dummy_ip6_datagram_recv_ctl(struct sock *sk, struct msghdr *msg,
+				       struct sk_buff *skb)
+{
+}
+static int dummy_icmpv6_err_convert(u8 type, u8 code, int *err)
+{
+	return -EAFNOSUPPORT;
+}
+static void dummy_ipv6_icmp_error(struct sock *sk, struct sk_buff *skb, int err,
+				  __be16 port, u32 info, u8 *payload) {}
+static int dummy_ipv6_chk_addr(struct net *net, const struct in6_addr *addr,
+			       const struct net_device *dev, int strict)
+{
+	return 0;
+}
+
+static int ping_v6_pre_connect(struct sock *sk, struct sockaddr_unsized *uaddr,
+			       int addr_len)
+{
+	/* This check is replicated from __ip6_datagram_connect() and
+	 * intended to prevent BPF program called below from accessing
+	 * bytes that are out of the bound specified by user in addr_len.
+	 */
+
+	if (addr_len < SIN6_LEN_RFC2133)
+		return -EINVAL;
+
+	return BPF_CGROUP_RUN_PROG_INET6_CONNECT_LOCK(sk, uaddr, &addr_len);
+}
+
+static int ping_v6_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
+{
+	struct inet_sock *inet = inet_sk(sk);
+	struct ipv6_pinfo *np = inet6_sk(sk);
+	struct icmp6hdr user_icmph;
+	int addr_type;
+	struct in6_addr *daddr;
+	int oif = 0;
+	struct flowi6 fl6;
+	int err;
+	struct dst_entry *dst;
+	struct rt6_info *rt;
+	struct pingfakehdr pfh;
+	struct ipcm6_cookie ipc6;
+
+	err = ping_common_sendmsg(AF_INET6, msg, len, &user_icmph,
+				  sizeof(user_icmph));
+	if (err)
+		return err;
+
+	memset(&fl6, 0, sizeof(fl6));
+
+	if (msg->msg_name) {
+		DECLARE_SOCKADDR(struct sockaddr_in6 *, u, msg->msg_name);
+		if (msg->msg_namelen < sizeof(*u))
+			return -EINVAL;
+		if (u->sin6_family != AF_INET6) {
+			return -EAFNOSUPPORT;
+		}
+		daddr = &(u->sin6_addr);
+		if (inet6_test_bit(SNDFLOW, sk))
+			fl6.flowlabel = u->sin6_flowinfo & IPV6_FLOWINFO_MASK;
+		if (__ipv6_addr_needs_scope_id(ipv6_addr_type(daddr)))
+			oif = u->sin6_scope_id;
+	} else {
+		if (sk->sk_state != TCP_ESTABLISHED)
+			return -EDESTADDRREQ;
+		daddr = &sk->sk_v6_daddr;
+		fl6.flowlabel = np->flow_label;
+	}
+
+	if (!oif)
+		oif = sk->sk_bound_dev_if;
+
+	if (!oif)
+		oif = np->sticky_pktinfo.ipi6_ifindex;
+
+	if (!oif && ipv6_addr_is_multicast(daddr))
+		oif = READ_ONCE(np->mcast_oif);
+	else if (!oif)
+		oif = READ_ONCE(np->ucast_oif);
+
+	addr_type = ipv6_addr_type(daddr);
+	if ((__ipv6_addr_needs_scope_id(addr_type) && !oif) ||
+	    (addr_type & IPV6_ADDR_MAPPED) ||
+	    (oif && sk->sk_bound_dev_if && oif != sk->sk_bound_dev_if &&
+	     l3mdev_master_ifindex_by_index(sock_net(sk), oif) != sk->sk_bound_dev_if))
+		return -EINVAL;
+
+	ipcm6_init_sk(&ipc6, sk);
+
+	fl6.flowi6_oif = oif;
+
+	if (msg->msg_controllen) {
+		struct ipv6_txoptions opt = {};
+
+		opt.tot_len = sizeof(opt);
+		ipc6.opt = &opt;
+
+		err = ip6_datagram_send_ctl(sock_net(sk), sk, msg, &fl6, &ipc6);
+		if (err < 0)
+			return err;
+
+		/* Changes to txoptions and flow info are not implemented, yet.
+		 * Drop the options.
+		 */
+		ipc6.opt = NULL;
+	}
+
+	fl6.flowi6_proto = IPPROTO_ICMPV6;
+	fl6.saddr = np->saddr;
+	fl6.daddr = *daddr;
+	fl6.flowi6_mark = ipc6.sockc.mark;
+	fl6.flowi6_uid = sk_uid(sk);
+	fl6.fl6_icmp_type = user_icmph.icmp6_type;
+	fl6.fl6_icmp_code = user_icmph.icmp6_code;
+	security_sk_classify_flow(sk, flowi6_to_flowi_common(&fl6));
+
+	fl6.flowlabel = ip6_make_flowinfo(ipc6.tclass, fl6.flowlabel);
+
+	dst = ip6_sk_dst_lookup_flow(sk, &fl6, daddr, false);
+	if (IS_ERR(dst))
+		return PTR_ERR(dst);
+	rt = dst_rt6_info(dst);
+
+	if (!fl6.flowi6_oif && ipv6_addr_is_multicast(&fl6.daddr))
+		fl6.flowi6_oif = READ_ONCE(np->mcast_oif);
+	else if (!fl6.flowi6_oif)
+		fl6.flowi6_oif = READ_ONCE(np->ucast_oif);
+
+	pfh.icmph.type = user_icmph.icmp6_type;
+	pfh.icmph.code = user_icmph.icmp6_code;
+	pfh.icmph.checksum = 0;
+	pfh.icmph.un.echo.id = inet->inet_sport;
+	pfh.icmph.un.echo.sequence = user_icmph.icmp6_sequence;
+	pfh.msg = msg;
+	pfh.wcheck = 0;
+	pfh.family = AF_INET6;
+
+	if (ipc6.hlimit < 0)
+		ipc6.hlimit = ip6_sk_dst_hoplimit(np, &fl6, dst);
+
+	lock_sock(sk);
+	err = ip6_append_data(sk, ping_getfrag, &pfh, len,
+			      sizeof(struct icmp6hdr), &ipc6, &fl6, rt,
+			      MSG_DONTWAIT);
+
+	if (err) {
+		ICMP6_INC_STATS(sock_net(sk), rt->rt6i_idev,
+				ICMP6_MIB_OUTERRORS);
+		ip6_flush_pending_frames(sk);
+	} else {
+		icmpv6_push_pending_frames(sk, &fl6,
+					   (struct icmp6hdr *)&pfh.icmph, len);
+	}
+	release_sock(sk);
+
+	dst_release(dst);
+
+	if (err)
+		return err;
+
+	return len;
+}
+
+struct proto pingv6_prot = {
+	.name =		"PINGv6",
+	.owner =	THIS_MODULE,
+	.init =		ping_init_sock,
+	.close =	ping_close,
+	.pre_connect =	ping_v6_pre_connect,
+	.connect =	ip6_datagram_connect_v6_only,
+	.disconnect =	__udp_disconnect,
+	.setsockopt =	ipv6_setsockopt,
+	.getsockopt =	ipv6_getsockopt,
+	.sendmsg =	ping_v6_sendmsg,
+	.recvmsg =	ping_recvmsg,
+	.bind =		ping_bind,
+	.backlog_rcv =	ping_queue_rcv_skb,
+	.unhash =	ping_unhash,
+	.get_port =	ping_get_port,
+	.put_port =	ping_unhash,
+	.obj_size =	sizeof(struct raw6_sock),
+	.ipv6_pinfo_offset = offsetof(struct raw6_sock, inet6),
+};
+EXPORT_SYMBOL_GPL(pingv6_prot);
+
+static struct inet_protosw pingv6_protosw = {
+	.type =      SOCK_DGRAM,
+	.protocol =  IPPROTO_ICMPV6,
+	.prot =      &pingv6_prot,
+	.ops =       &inet6_sockraw_ops,
+	.flags =     INET_PROTOSW_REUSE,
+};
+
+#ifdef CONFIG_PROC_FS
+static void *ping_v6_seq_start(struct seq_file *seq, loff_t *pos)
+{
+	return ping_seq_start(seq, pos, AF_INET6);
+}
+
+static int ping_v6_seq_show(struct seq_file *seq, void *v)
+{
+	if (v == SEQ_START_TOKEN) {
+		seq_puts(seq, IPV6_SEQ_DGRAM_HEADER);
+	} else {
+		int bucket = ((struct ping_iter_state *) seq->private)->bucket;
+		struct inet_sock *inet = inet_sk((struct sock *)v);
+		__u16 srcp = ntohs(inet->inet_sport);
+		__u16 destp = ntohs(inet->inet_dport);
+		ip6_dgram_sock_seq_show(seq, v, srcp, destp, bucket);
+	}
+	return 0;
+}
+
+static const struct seq_operations ping_v6_seq_ops = {
+	.start		= ping_v6_seq_start,
+	.show		= ping_v6_seq_show,
+	.next		= ping_seq_next,
+	.stop		= ping_seq_stop,
+};
+
+static int __net_init ping_v6_proc_init_net(struct net *net)
+{
+	if (!proc_create_net("icmp6", 0444, net->proc_net, &ping_v6_seq_ops,
+			sizeof(struct ping_iter_state)))
+		return -ENOMEM;
+	return 0;
+}
+
+static void __net_exit ping_v6_proc_exit_net(struct net *net)
+{
+	remove_proc_entry("icmp6", net->proc_net);
+}
+
+static struct pernet_operations ping_v6_net_ops = {
+	.init = ping_v6_proc_init_net,
+	.exit = ping_v6_proc_exit_net,
+};
+#endif
+
+int __init pingv6_init(void)
+{
+#ifdef CONFIG_PROC_FS
+	int ret = register_pernet_subsys(&ping_v6_net_ops);
+	if (ret)
+		return ret;
+#endif
+	pingv6_ops.ipv6_recv_error = ipv6_recv_error;
+	pingv6_ops.ip6_datagram_recv_common_ctl = ip6_datagram_recv_common_ctl;
+	pingv6_ops.ip6_datagram_recv_specific_ctl =
+		ip6_datagram_recv_specific_ctl;
+	pingv6_ops.icmpv6_err_convert = icmpv6_err_convert;
+	pingv6_ops.ipv6_icmp_error = ipv6_icmp_error;
+	pingv6_ops.ipv6_chk_addr = ipv6_chk_addr;
+	return inet6_register_protosw(&pingv6_protosw);
+}
+
+/* This never gets called because it's not possible to unload the ipv6 module,
+ * but just in case.
+ */
+void pingv6_exit(void)
+{
+	pingv6_ops.ipv6_recv_error = dummy_ipv6_recv_error;
+	pingv6_ops.ip6_datagram_recv_common_ctl = dummy_ip6_datagram_recv_ctl;
+	pingv6_ops.ip6_datagram_recv_specific_ctl = dummy_ip6_datagram_recv_ctl;
+	pingv6_ops.icmpv6_err_convert = dummy_icmpv6_err_convert;
+	pingv6_ops.ipv6_icmp_error = dummy_ipv6_icmp_error;
+	pingv6_ops.ipv6_chk_addr = dummy_ipv6_chk_addr;
+#ifdef CONFIG_PROC_FS
+	unregister_pernet_subsys(&ping_v6_net_ops);
+#endif
+	inet6_unregister_protosw(&pingv6_protosw);
+}