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, 535 insertions, 0 deletions

diff --git a/net/psample/psample.c b/net/psample/psample.c
new file mode 100644
index 000000000..c112e1f0c
--- /dev/null
+++ b/net/psample/psample.c
@@ -0,0 +1,535 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * net/psample/psample.c - Netlink channel for packet sampling
+ * Copyright (c) 2017 Yotam Gigi <yotamg@mellanox.com>
+ */
+
+#include <linux/types.h>
+#include <linux/kernel.h>
+#include <linux/skbuff.h>
+#include <linux/module.h>
+#include <linux/timekeeping.h>
+#include <net/net_namespace.h>
+#include <net/sock.h>
+#include <net/netlink.h>
+#include <net/genetlink.h>
+#include <net/psample.h>
+#include <linux/spinlock.h>
+#include <net/ip_tunnels.h>
+#include <net/dst_metadata.h>
+
+#define PSAMPLE_MAX_PACKET_SIZE 0xffff
+
+static LIST_HEAD(psample_groups_list);
+static DEFINE_SPINLOCK(psample_groups_lock);
+
+/* multicast groups */
+enum psample_nl_multicast_groups {
+	PSAMPLE_NL_MCGRP_CONFIG,
+	PSAMPLE_NL_MCGRP_SAMPLE,
+};
+
+static const struct genl_multicast_group psample_nl_mcgrps[] = {
+	[PSAMPLE_NL_MCGRP_CONFIG] = { .name = PSAMPLE_NL_MCGRP_CONFIG_NAME },
+	[PSAMPLE_NL_MCGRP_SAMPLE] = { .name = PSAMPLE_NL_MCGRP_SAMPLE_NAME,
+				      .flags = GENL_MCAST_CAP_NET_ADMIN, },
+};
+
+static struct genl_family psample_nl_family __ro_after_init;
+
+static int psample_group_nl_fill(struct sk_buff *msg,
+				 struct psample_group *group,
+				 enum psample_command cmd, u32 portid, u32 seq,
+				 int flags)
+{
+	void *hdr;
+	int ret;
+
+	hdr = genlmsg_put(msg, portid, seq, &psample_nl_family, flags, cmd);
+	if (!hdr)
+		return -EMSGSIZE;
+
+	ret = nla_put_u32(msg, PSAMPLE_ATTR_SAMPLE_GROUP, group->group_num);
+	if (ret < 0)
+		goto error;
+
+	ret = nla_put_u32(msg, PSAMPLE_ATTR_GROUP_REFCOUNT, group->refcount);
+	if (ret < 0)
+		goto error;
+
+	ret = nla_put_u32(msg, PSAMPLE_ATTR_GROUP_SEQ, group->seq);
+	if (ret < 0)
+		goto error;
+
+	genlmsg_end(msg, hdr);
+	return 0;
+
+error:
+	genlmsg_cancel(msg, hdr);
+	return -EMSGSIZE;
+}
+
+static int psample_nl_cmd_get_group_dumpit(struct sk_buff *msg,
+					   struct netlink_callback *cb)
+{
+	struct psample_group *group;
+	int start = cb->args[0];
+	int idx = 0;
+	int err;
+
+	spin_lock_bh(&psample_groups_lock);
+	list_for_each_entry(group, &psample_groups_list, list) {
+		if (!net_eq(group->net, sock_net(msg->sk)))
+			continue;
+		if (idx < start) {
+			idx++;
+			continue;
+		}
+		err = psample_group_nl_fill(msg, group, PSAMPLE_CMD_NEW_GROUP,
+					    NETLINK_CB(cb->skb).portid,
+					    cb->nlh->nlmsg_seq, NLM_F_MULTI);
+		if (err)
+			break;
+		idx++;
+	}
+
+	spin_unlock_bh(&psample_groups_lock);
+	cb->args[0] = idx;
+	return msg->len;
+}
+
+static const struct genl_small_ops psample_nl_ops[] = {
+	{
+		.cmd = PSAMPLE_CMD_GET_GROUP,
+		.validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
+		.dumpit = psample_nl_cmd_get_group_dumpit,
+		/* can be retrieved by unprivileged users */
+	}
+};
+
+static struct genl_family psample_nl_family __ro_after_init = {
+	.name		= PSAMPLE_GENL_NAME,
+	.version	= PSAMPLE_GENL_VERSION,
+	.maxattr	= PSAMPLE_ATTR_MAX,
+	.netnsok	= true,
+	.module		= THIS_MODULE,
+	.mcgrps		= psample_nl_mcgrps,
+	.small_ops	= psample_nl_ops,
+	.n_small_ops	= ARRAY_SIZE(psample_nl_ops),
+	.resv_start_op	= PSAMPLE_CMD_GET_GROUP + 1,
+	.n_mcgrps	= ARRAY_SIZE(psample_nl_mcgrps),
+};
+
+static void psample_group_notify(struct psample_group *group,
+				 enum psample_command cmd)
+{
+	struct sk_buff *msg;
+	int err;
+
+	msg = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_ATOMIC);
+	if (!msg)
+		return;
+
+	err = psample_group_nl_fill(msg, group, cmd, 0, 0, NLM_F_MULTI);
+	if (!err)
+		genlmsg_multicast_netns(&psample_nl_family, group->net, msg, 0,
+					PSAMPLE_NL_MCGRP_CONFIG, GFP_ATOMIC);
+	else
+		nlmsg_free(msg);
+}
+
+static struct psample_group *psample_group_create(struct net *net,
+						  u32 group_num)
+{
+	struct psample_group *group;
+
+	group = kzalloc_obj(*group, GFP_ATOMIC);
+	if (!group)
+		return NULL;
+
+	group->net = net;
+	group->group_num = group_num;
+	list_add_tail(&group->list, &psample_groups_list);
+
+	psample_group_notify(group, PSAMPLE_CMD_NEW_GROUP);
+	return group;
+}
+
+static void psample_group_destroy(struct psample_group *group)
+{
+	psample_group_notify(group, PSAMPLE_CMD_DEL_GROUP);
+	list_del(&group->list);
+	kfree_rcu(group, rcu);
+}
+
+static struct psample_group *
+psample_group_lookup(struct net *net, u32 group_num)
+{
+	struct psample_group *group;
+
+	list_for_each_entry(group, &psample_groups_list, list)
+		if ((group->group_num == group_num) && (group->net == net))
+			return group;
+	return NULL;
+}
+
+struct psample_group *psample_group_get(struct net *net, u32 group_num)
+{
+	struct psample_group *group;
+
+	spin_lock_bh(&psample_groups_lock);
+
+	group = psample_group_lookup(net, group_num);
+	if (!group) {
+		group = psample_group_create(net, group_num);
+		if (!group)
+			goto out;
+	}
+	group->refcount++;
+
+out:
+	spin_unlock_bh(&psample_groups_lock);
+	return group;
+}
+EXPORT_SYMBOL_GPL(psample_group_get);
+
+void psample_group_take(struct psample_group *group)
+{
+	spin_lock_bh(&psample_groups_lock);
+	group->refcount++;
+	spin_unlock_bh(&psample_groups_lock);
+}
+EXPORT_SYMBOL_GPL(psample_group_take);
+
+void psample_group_put(struct psample_group *group)
+{
+	spin_lock_bh(&psample_groups_lock);
+
+	if (--group->refcount == 0)
+		psample_group_destroy(group);
+
+	spin_unlock_bh(&psample_groups_lock);
+}
+EXPORT_SYMBOL_GPL(psample_group_put);
+
+#ifdef CONFIG_INET
+static int __psample_ip_tun_to_nlattr(struct sk_buff *skb,
+			      struct ip_tunnel_info *tun_info)
+{
+	unsigned short tun_proto = ip_tunnel_info_af(tun_info);
+	const void *tun_opts = ip_tunnel_info_opts(tun_info);
+	const struct ip_tunnel_key *tun_key = &tun_info->key;
+	int tun_opts_len = tun_info->options_len;
+
+	if (test_bit(IP_TUNNEL_KEY_BIT, tun_key->tun_flags) &&
+	    nla_put_be64(skb, PSAMPLE_TUNNEL_KEY_ATTR_ID, tun_key->tun_id,
+			 PSAMPLE_TUNNEL_KEY_ATTR_PAD))
+		return -EMSGSIZE;
+
+	if (tun_info->mode & IP_TUNNEL_INFO_BRIDGE &&
+	    nla_put_flag(skb, PSAMPLE_TUNNEL_KEY_ATTR_IPV4_INFO_BRIDGE))
+		return -EMSGSIZE;
+
+	switch (tun_proto) {
+	case AF_INET:
+		if (tun_key->u.ipv4.src &&
+		    nla_put_in_addr(skb, PSAMPLE_TUNNEL_KEY_ATTR_IPV4_SRC,
+				    tun_key->u.ipv4.src))
+			return -EMSGSIZE;
+		if (tun_key->u.ipv4.dst &&
+		    nla_put_in_addr(skb, PSAMPLE_TUNNEL_KEY_ATTR_IPV4_DST,
+				    tun_key->u.ipv4.dst))
+			return -EMSGSIZE;
+		break;
+	case AF_INET6:
+		if (!ipv6_addr_any(&tun_key->u.ipv6.src) &&
+		    nla_put_in6_addr(skb, PSAMPLE_TUNNEL_KEY_ATTR_IPV6_SRC,
+				     &tun_key->u.ipv6.src))
+			return -EMSGSIZE;
+		if (!ipv6_addr_any(&tun_key->u.ipv6.dst) &&
+		    nla_put_in6_addr(skb, PSAMPLE_TUNNEL_KEY_ATTR_IPV6_DST,
+				     &tun_key->u.ipv6.dst))
+			return -EMSGSIZE;
+		break;
+	}
+	if (tun_key->tos &&
+	    nla_put_u8(skb, PSAMPLE_TUNNEL_KEY_ATTR_TOS, tun_key->tos))
+		return -EMSGSIZE;
+	if (nla_put_u8(skb, PSAMPLE_TUNNEL_KEY_ATTR_TTL, tun_key->ttl))
+		return -EMSGSIZE;
+	if (test_bit(IP_TUNNEL_DONT_FRAGMENT_BIT, tun_key->tun_flags) &&
+	    nla_put_flag(skb, PSAMPLE_TUNNEL_KEY_ATTR_DONT_FRAGMENT))
+		return -EMSGSIZE;
+	if (test_bit(IP_TUNNEL_CSUM_BIT, tun_key->tun_flags) &&
+	    nla_put_flag(skb, PSAMPLE_TUNNEL_KEY_ATTR_CSUM))
+		return -EMSGSIZE;
+	if (tun_key->tp_src &&
+	    nla_put_be16(skb, PSAMPLE_TUNNEL_KEY_ATTR_TP_SRC, tun_key->tp_src))
+		return -EMSGSIZE;
+	if (tun_key->tp_dst &&
+	    nla_put_be16(skb, PSAMPLE_TUNNEL_KEY_ATTR_TP_DST, tun_key->tp_dst))
+		return -EMSGSIZE;
+	if (test_bit(IP_TUNNEL_OAM_BIT, tun_key->tun_flags) &&
+	    nla_put_flag(skb, PSAMPLE_TUNNEL_KEY_ATTR_OAM))
+		return -EMSGSIZE;
+	if (tun_opts_len) {
+		if (test_bit(IP_TUNNEL_GENEVE_OPT_BIT, tun_key->tun_flags) &&
+		    nla_put(skb, PSAMPLE_TUNNEL_KEY_ATTR_GENEVE_OPTS,
+			    tun_opts_len, tun_opts))
+			return -EMSGSIZE;
+		else if (test_bit(IP_TUNNEL_ERSPAN_OPT_BIT,
+				  tun_key->tun_flags) &&
+			 nla_put(skb, PSAMPLE_TUNNEL_KEY_ATTR_ERSPAN_OPTS,
+				 tun_opts_len, tun_opts))
+			return -EMSGSIZE;
+	}
+
+	return 0;
+}
+
+static int psample_ip_tun_to_nlattr(struct sk_buff *skb,
+			    struct ip_tunnel_info *tun_info)
+{
+	struct nlattr *nla;
+	int err;
+
+	nla = nla_nest_start_noflag(skb, PSAMPLE_ATTR_TUNNEL);
+	if (!nla)
+		return -EMSGSIZE;
+
+	err = __psample_ip_tun_to_nlattr(skb, tun_info);
+	if (err) {
+		nla_nest_cancel(skb, nla);
+		return err;
+	}
+
+	nla_nest_end(skb, nla);
+
+	return 0;
+}
+
+static int psample_tunnel_meta_len(struct ip_tunnel_info *tun_info)
+{
+	unsigned short tun_proto = ip_tunnel_info_af(tun_info);
+	const struct ip_tunnel_key *tun_key = &tun_info->key;
+	int tun_opts_len = tun_info->options_len;
+	int sum = nla_total_size(0);	/* PSAMPLE_ATTR_TUNNEL */
+
+	if (test_bit(IP_TUNNEL_KEY_BIT, tun_key->tun_flags))
+		sum += nla_total_size_64bit(sizeof(u64));
+
+	if (tun_info->mode & IP_TUNNEL_INFO_BRIDGE)
+		sum += nla_total_size(0);
+
+	switch (tun_proto) {
+	case AF_INET:
+		if (tun_key->u.ipv4.src)
+			sum += nla_total_size(sizeof(u32));
+		if (tun_key->u.ipv4.dst)
+			sum += nla_total_size(sizeof(u32));
+		break;
+	case AF_INET6:
+		if (!ipv6_addr_any(&tun_key->u.ipv6.src))
+			sum += nla_total_size(sizeof(struct in6_addr));
+		if (!ipv6_addr_any(&tun_key->u.ipv6.dst))
+			sum += nla_total_size(sizeof(struct in6_addr));
+		break;
+	}
+	if (tun_key->tos)
+		sum += nla_total_size(sizeof(u8));
+	sum += nla_total_size(sizeof(u8));	/* TTL */
+	if (test_bit(IP_TUNNEL_DONT_FRAGMENT_BIT, tun_key->tun_flags))
+		sum += nla_total_size(0);
+	if (test_bit(IP_TUNNEL_CSUM_BIT, tun_key->tun_flags))
+		sum += nla_total_size(0);
+	if (tun_key->tp_src)
+		sum += nla_total_size(sizeof(u16));
+	if (tun_key->tp_dst)
+		sum += nla_total_size(sizeof(u16));
+	if (test_bit(IP_TUNNEL_OAM_BIT, tun_key->tun_flags))
+		sum += nla_total_size(0);
+	if (tun_opts_len) {
+		if (test_bit(IP_TUNNEL_GENEVE_OPT_BIT, tun_key->tun_flags))
+			sum += nla_total_size(tun_opts_len);
+		else if (test_bit(IP_TUNNEL_ERSPAN_OPT_BIT,
+				  tun_key->tun_flags))
+			sum += nla_total_size(tun_opts_len);
+	}
+
+	return sum;
+}
+#endif
+
+void psample_sample_packet(struct psample_group *group,
+			   const struct sk_buff *skb, u32 sample_rate,
+			   const struct psample_metadata *md)
+{
+	ktime_t tstamp = ktime_get_real();
+	int out_ifindex = md->out_ifindex;
+	int in_ifindex = md->in_ifindex;
+	u32 trunc_size = md->trunc_size;
+#ifdef CONFIG_INET
+	struct ip_tunnel_info *tun_info;
+#endif
+	struct sk_buff *nl_skb;
+	int data_len;
+	int meta_len;
+	void *data;
+	int ret;
+
+	if (!genl_has_listeners(&psample_nl_family, group->net,
+				PSAMPLE_NL_MCGRP_SAMPLE))
+		return;
+
+	meta_len = (in_ifindex ? nla_total_size(sizeof(u16)) : 0) +
+		   (out_ifindex ? nla_total_size(sizeof(u16)) : 0) +
+		   (md->out_tc_valid ? nla_total_size(sizeof(u16)) : 0) +
+		   (md->out_tc_occ_valid ? nla_total_size_64bit(sizeof(u64)) : 0) +
+		   (md->latency_valid ? nla_total_size_64bit(sizeof(u64)) : 0) +
+		   nla_total_size(sizeof(u32)) +	/* sample_rate */
+		   nla_total_size(sizeof(u32)) +	/* orig_size */
+		   nla_total_size(sizeof(u32)) +	/* group_num */
+		   nla_total_size(sizeof(u32)) +	/* seq */
+		   nla_total_size_64bit(sizeof(u64)) +	/* timestamp */
+		   nla_total_size(sizeof(u16)) +	/* protocol */
+		   (md->user_cookie_len ?
+		    nla_total_size(md->user_cookie_len) : 0) + /* user cookie */
+		   (md->rate_as_probability ?
+		    nla_total_size(0) : 0);	/* rate as probability */
+
+#ifdef CONFIG_INET
+	tun_info = skb_tunnel_info(skb);
+	if (tun_info)
+		meta_len += psample_tunnel_meta_len(tun_info);
+#endif
+
+	data_len = min(skb->len, trunc_size);
+	if (meta_len + nla_total_size(data_len) > PSAMPLE_MAX_PACKET_SIZE)
+		data_len = PSAMPLE_MAX_PACKET_SIZE - meta_len - NLA_HDRLEN
+			    - NLA_ALIGNTO;
+
+	nl_skb = genlmsg_new(meta_len + nla_total_size(data_len), GFP_ATOMIC);
+	if (unlikely(!nl_skb))
+		return;
+
+	data = genlmsg_put(nl_skb, 0, 0, &psample_nl_family, 0,
+			   PSAMPLE_CMD_SAMPLE);
+	if (unlikely(!data))
+		goto error;
+
+	if (in_ifindex) {
+		ret = nla_put_u16(nl_skb, PSAMPLE_ATTR_IIFINDEX, in_ifindex);
+		if (unlikely(ret < 0))
+			goto error;
+	}
+
+	if (out_ifindex) {
+		ret = nla_put_u16(nl_skb, PSAMPLE_ATTR_OIFINDEX, out_ifindex);
+		if (unlikely(ret < 0))
+			goto error;
+	}
+
+	ret = nla_put_u32(nl_skb, PSAMPLE_ATTR_SAMPLE_RATE, sample_rate);
+	if (unlikely(ret < 0))
+		goto error;
+
+	ret = nla_put_u32(nl_skb, PSAMPLE_ATTR_ORIGSIZE, skb->len);
+	if (unlikely(ret < 0))
+		goto error;
+
+	ret = nla_put_u32(nl_skb, PSAMPLE_ATTR_SAMPLE_GROUP, group->group_num);
+	if (unlikely(ret < 0))
+		goto error;
+
+	ret = nla_put_u32(nl_skb, PSAMPLE_ATTR_GROUP_SEQ, group->seq++);
+	if (unlikely(ret < 0))
+		goto error;
+
+	if (md->out_tc_valid) {
+		ret = nla_put_u16(nl_skb, PSAMPLE_ATTR_OUT_TC, md->out_tc);
+		if (unlikely(ret < 0))
+			goto error;
+	}
+
+	if (md->out_tc_occ_valid) {
+		ret = nla_put_u64_64bit(nl_skb, PSAMPLE_ATTR_OUT_TC_OCC,
+					md->out_tc_occ, PSAMPLE_ATTR_PAD);
+		if (unlikely(ret < 0))
+			goto error;
+	}
+
+	if (md->latency_valid) {
+		ret = nla_put_u64_64bit(nl_skb, PSAMPLE_ATTR_LATENCY,
+					md->latency, PSAMPLE_ATTR_PAD);
+		if (unlikely(ret < 0))
+			goto error;
+	}
+
+	ret = nla_put_u64_64bit(nl_skb, PSAMPLE_ATTR_TIMESTAMP,
+				ktime_to_ns(tstamp), PSAMPLE_ATTR_PAD);
+	if (unlikely(ret < 0))
+		goto error;
+
+	ret = nla_put_u16(nl_skb, PSAMPLE_ATTR_PROTO,
+			  be16_to_cpu(skb->protocol));
+	if (unlikely(ret < 0))
+		goto error;
+
+	if (data_len) {
+		int nla_len = nla_attr_size(data_len);
+		struct nlattr *nla;
+
+		nla = skb_put(nl_skb, nla_len);
+		nla->nla_type = PSAMPLE_ATTR_DATA;
+		nla->nla_len = nla_len;
+
+		if (skb_copy_bits(skb, 0, nla_data(nla), data_len))
+			goto error;
+
+		skb_put_zero(nl_skb, nla_padlen(data_len));
+	}
+
+#ifdef CONFIG_INET
+	if (tun_info) {
+		ret = psample_ip_tun_to_nlattr(nl_skb, tun_info);
+		if (unlikely(ret < 0))
+			goto error;
+	}
+#endif
+
+	if (md->user_cookie && md->user_cookie_len &&
+	    nla_put(nl_skb, PSAMPLE_ATTR_USER_COOKIE, md->user_cookie_len,
+		    md->user_cookie))
+		goto error;
+
+	if (md->rate_as_probability &&
+	    nla_put_flag(nl_skb, PSAMPLE_ATTR_SAMPLE_PROBABILITY))
+		goto error;
+
+	genlmsg_end(nl_skb, data);
+	genlmsg_multicast_netns(&psample_nl_family, group->net, nl_skb, 0,
+				PSAMPLE_NL_MCGRP_SAMPLE, GFP_ATOMIC);
+
+	return;
+error:
+	pr_err_ratelimited("Could not create psample log message\n");
+	nlmsg_free(nl_skb);
+}
+EXPORT_SYMBOL_GPL(psample_sample_packet);
+
+static int __init psample_module_init(void)
+{
+	return genl_register_family(&psample_nl_family);
+}
+
+static void __exit psample_module_exit(void)
+{
+	genl_unregister_family(&psample_nl_family);
+}
+
+module_init(psample_module_init);
+module_exit(psample_module_exit);
+
+MODULE_AUTHOR("Yotam Gigi <yotam.gi@gmail.com>");
+MODULE_DESCRIPTION("netlink channel for packet sampling");
+MODULE_LICENSE("GPL v2");