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, 321 insertions, 0 deletions

diff --git a/net/ipv6/seg6_hmac.c b/net/ipv6/seg6_hmac.c
new file mode 100644
index 000000000..e6964c6b0
--- /dev/null
+++ b/net/ipv6/seg6_hmac.c
@@ -0,0 +1,321 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *  SR-IPv6 implementation -- HMAC functions
+ *
+ *  Author:
+ *  David Lebrun <david.lebrun@uclouvain.be>
+ */
+
+#include <linux/errno.h>
+#include <linux/kernel.h>
+#include <linux/types.h>
+#include <linux/socket.h>
+#include <linux/sockios.h>
+#include <linux/net.h>
+#include <linux/netdevice.h>
+#include <linux/in6.h>
+#include <linux/icmpv6.h>
+#include <linux/mroute6.h>
+#include <linux/rhashtable.h>
+
+#include <linux/netfilter.h>
+#include <linux/netfilter_ipv6.h>
+
+#include <net/sock.h>
+#include <net/snmp.h>
+
+#include <net/ipv6.h>
+#include <net/protocol.h>
+#include <net/transp_v6.h>
+#include <net/rawv6.h>
+#include <net/ndisc.h>
+#include <net/ip6_route.h>
+#include <net/addrconf.h>
+#include <net/xfrm.h>
+
+#include <crypto/sha1.h>
+#include <crypto/sha2.h>
+#include <crypto/utils.h>
+#include <net/seg6.h>
+#include <net/genetlink.h>
+#include <net/seg6_hmac.h>
+#include <linux/random.h>
+
+struct hmac_storage {
+	local_lock_t bh_lock;
+	char hmac_ring[SEG6_HMAC_RING_SIZE];
+};
+
+static DEFINE_PER_CPU(struct hmac_storage, hmac_storage) = {
+	.bh_lock = INIT_LOCAL_LOCK(bh_lock),
+};
+
+static int seg6_hmac_cmpfn(struct rhashtable_compare_arg *arg, const void *obj)
+{
+	const struct seg6_hmac_info *hinfo = obj;
+
+	return (hinfo->hmackeyid != *(__u32 *)arg->key);
+}
+
+static inline void seg6_hinfo_release(struct seg6_hmac_info *hinfo)
+{
+	kfree_rcu(hinfo, rcu);
+}
+
+static void seg6_free_hi(void *ptr, void *arg)
+{
+	struct seg6_hmac_info *hinfo = (struct seg6_hmac_info *)ptr;
+
+	if (hinfo)
+		seg6_hinfo_release(hinfo);
+}
+
+static const struct rhashtable_params rht_params = {
+	.head_offset		= offsetof(struct seg6_hmac_info, node),
+	.key_offset		= offsetof(struct seg6_hmac_info, hmackeyid),
+	.key_len		= sizeof(u32),
+	.automatic_shrinking	= true,
+	.obj_cmpfn		= seg6_hmac_cmpfn,
+};
+
+static struct sr6_tlv_hmac *seg6_get_tlv_hmac(struct ipv6_sr_hdr *srh)
+{
+	struct sr6_tlv_hmac *tlv;
+
+	if (srh->hdrlen < (srh->first_segment + 1) * 2 + 5)
+		return NULL;
+
+	if (!sr_has_hmac(srh))
+		return NULL;
+
+	tlv = (struct sr6_tlv_hmac *)
+	      ((char *)srh + ((srh->hdrlen + 1) << 3) - 40);
+
+	if (tlv->tlvhdr.type != SR6_TLV_HMAC || tlv->tlvhdr.len != 38)
+		return NULL;
+
+	return tlv;
+}
+
+int seg6_hmac_compute(struct seg6_hmac_info *hinfo, struct ipv6_sr_hdr *hdr,
+		      struct in6_addr *saddr, u8 *output)
+{
+	__be32 hmackeyid = cpu_to_be32(hinfo->hmackeyid);
+	int plen, i, ret = 0;
+	char *ring, *off;
+
+	/* saddr(16) + first_seg(1) + flags(1) + keyid(4) + seglist(16n) */
+	plen = 16 + 1 + 1 + 4 + (hdr->first_segment + 1) * 16;
+
+	/* this limit allows for 14 segments */
+	if (plen >= SEG6_HMAC_RING_SIZE)
+		return -EMSGSIZE;
+
+	/* Let's build the HMAC text on the ring buffer. The text is composed
+	 * as follows, in order:
+	 *
+	 * 1. Source IPv6 address (128 bits)
+	 * 2. first_segment value (8 bits)
+	 * 3. Flags (8 bits)
+	 * 4. HMAC Key ID (32 bits)
+	 * 5. All segments in the segments list (n * 128 bits)
+	 */
+
+	local_bh_disable();
+	local_lock_nested_bh(&hmac_storage.bh_lock);
+	ring = this_cpu_ptr(hmac_storage.hmac_ring);
+	off = ring;
+
+	/* source address */
+	memcpy(off, saddr, 16);
+	off += 16;
+
+	/* first_segment value */
+	*off++ = hdr->first_segment;
+
+	/* flags */
+	*off++ = hdr->flags;
+
+	/* HMAC Key ID */
+	memcpy(off, &hmackeyid, 4);
+	off += 4;
+
+	/* all segments in the list */
+	for (i = 0; i < hdr->first_segment + 1; i++) {
+		memcpy(off, hdr->segments + i, 16);
+		off += 16;
+	}
+
+	switch (hinfo->alg_id) {
+	case SEG6_HMAC_ALGO_SHA1:
+		hmac_sha1(&hinfo->key.sha1, ring, plen, output);
+		static_assert(SEG6_HMAC_FIELD_LEN > SHA1_DIGEST_SIZE);
+		memset(&output[SHA1_DIGEST_SIZE], 0,
+		       SEG6_HMAC_FIELD_LEN - SHA1_DIGEST_SIZE);
+		break;
+	case SEG6_HMAC_ALGO_SHA256:
+		hmac_sha256(&hinfo->key.sha256, ring, plen, output);
+		static_assert(SEG6_HMAC_FIELD_LEN == SHA256_DIGEST_SIZE);
+		break;
+	default:
+		WARN_ON_ONCE(1);
+		ret = -EINVAL;
+		break;
+	}
+	local_unlock_nested_bh(&hmac_storage.bh_lock);
+	local_bh_enable();
+	return ret;
+}
+EXPORT_SYMBOL(seg6_hmac_compute);
+
+/* checks if an incoming SR-enabled packet's HMAC status matches
+ * the incoming policy.
+ *
+ * called with rcu_read_lock()
+ */
+bool seg6_hmac_validate_skb(struct sk_buff *skb)
+{
+	u8 hmac_output[SEG6_HMAC_FIELD_LEN];
+	struct net *net = dev_net(skb->dev);
+	struct seg6_hmac_info *hinfo;
+	struct sr6_tlv_hmac *tlv;
+	struct ipv6_sr_hdr *srh;
+	struct inet6_dev *idev;
+	int require_hmac;
+
+	idev = __in6_dev_get(skb->dev);
+	if (!idev)
+		return false;
+
+	srh = (struct ipv6_sr_hdr *)skb_transport_header(skb);
+
+	tlv = seg6_get_tlv_hmac(srh);
+
+	require_hmac = READ_ONCE(idev->cnf.seg6_require_hmac);
+	/* mandatory check but no tlv */
+	if (require_hmac > 0 && !tlv)
+		return false;
+
+	/* no check */
+	if (require_hmac < 0)
+		return true;
+
+	/* check only if present */
+	if (require_hmac == 0 && !tlv)
+		return true;
+
+	/* now, seg6_require_hmac >= 0 && tlv */
+
+	hinfo = seg6_hmac_info_lookup(net, be32_to_cpu(tlv->hmackeyid));
+	if (!hinfo)
+		return false;
+
+	if (seg6_hmac_compute(hinfo, srh, &ipv6_hdr(skb)->saddr, hmac_output))
+		return false;
+
+	if (crypto_memneq(hmac_output, tlv->hmac, SEG6_HMAC_FIELD_LEN))
+		return false;
+
+	return true;
+}
+EXPORT_SYMBOL(seg6_hmac_validate_skb);
+
+/* called with rcu_read_lock() */
+struct seg6_hmac_info *seg6_hmac_info_lookup(struct net *net, u32 key)
+{
+	struct seg6_pernet_data *sdata = seg6_pernet(net);
+	struct seg6_hmac_info *hinfo;
+
+	hinfo = rhashtable_lookup_fast(&sdata->hmac_infos, &key, rht_params);
+
+	return hinfo;
+}
+EXPORT_SYMBOL(seg6_hmac_info_lookup);
+
+int seg6_hmac_info_add(struct net *net, u32 key, struct seg6_hmac_info *hinfo)
+{
+	struct seg6_pernet_data *sdata = seg6_pernet(net);
+	int err;
+
+	switch (hinfo->alg_id) {
+	case SEG6_HMAC_ALGO_SHA1:
+		hmac_sha1_preparekey(&hinfo->key.sha1,
+				     hinfo->secret, hinfo->slen);
+		break;
+	case SEG6_HMAC_ALGO_SHA256:
+		hmac_sha256_preparekey(&hinfo->key.sha256,
+				       hinfo->secret, hinfo->slen);
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	err = rhashtable_lookup_insert_fast(&sdata->hmac_infos, &hinfo->node,
+					    rht_params);
+
+	return err;
+}
+EXPORT_SYMBOL(seg6_hmac_info_add);
+
+int seg6_hmac_info_del(struct net *net, u32 key)
+{
+	struct seg6_pernet_data *sdata = seg6_pernet(net);
+	struct seg6_hmac_info *hinfo;
+	int err = -ENOENT;
+
+	hinfo = rhashtable_lookup_fast(&sdata->hmac_infos, &key, rht_params);
+	if (!hinfo)
+		goto out;
+
+	err = rhashtable_remove_fast(&sdata->hmac_infos, &hinfo->node,
+				     rht_params);
+	if (err)
+		goto out;
+
+	seg6_hinfo_release(hinfo);
+
+out:
+	return err;
+}
+EXPORT_SYMBOL(seg6_hmac_info_del);
+
+int seg6_push_hmac(struct net *net, struct in6_addr *saddr,
+		   struct ipv6_sr_hdr *srh)
+{
+	struct seg6_hmac_info *hinfo;
+	struct sr6_tlv_hmac *tlv;
+	int err = -ENOENT;
+
+	tlv = seg6_get_tlv_hmac(srh);
+	if (!tlv)
+		return -EINVAL;
+
+	rcu_read_lock();
+
+	hinfo = seg6_hmac_info_lookup(net, be32_to_cpu(tlv->hmackeyid));
+	if (!hinfo)
+		goto out;
+
+	memset(tlv->hmac, 0, SEG6_HMAC_FIELD_LEN);
+	err = seg6_hmac_compute(hinfo, srh, saddr, tlv->hmac);
+
+out:
+	rcu_read_unlock();
+	return err;
+}
+EXPORT_SYMBOL(seg6_push_hmac);
+
+int __net_init seg6_hmac_net_init(struct net *net)
+{
+	struct seg6_pernet_data *sdata = seg6_pernet(net);
+
+	return rhashtable_init(&sdata->hmac_infos, &rht_params);
+}
+
+void __net_exit seg6_hmac_net_exit(struct net *net)
+{
+	struct seg6_pernet_data *sdata = seg6_pernet(net);
+
+	rhashtable_free_and_destroy(&sdata->hmac_infos, seg6_free_hi, NULL);
+}
+EXPORT_SYMBOL(seg6_hmac_net_exit);