Merge tag 'net-next-6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-nextgrafted

Pull networking updates from Jakub Kicinski:
 "Core:

   - Add dedicated kmem_cache for typical/small skb->head, avoid having
     to access struct page at kfree time, and improve memory use.

   - Introduce sysctl to set default RPS configuration for new netdevs.

   - Define Netlink protocol specification format which can be used to
     describe messages used by each family and auto-generate parsers.
     Add tools for generating kernel data structures and uAPI headers.

   - Expose all net/core sysctls inside netns.

   - Remove 4s sleep in netpoll if carrier is instantly detected on
     boot.

   - Add configurable limit of MDB entries per port, and port-vlan.

   - Continue populating drop reasons throughout the stack.

   - Retire a handful of legacy Qdiscs and classifiers.

  Protocols:

   - Support IPv4 big TCP (TSO frames larger than 64kB).

   - Add IP_LOCAL_PORT_RANGE socket option, to control local port range
     on socket by socket basis.

   - Track and report in procfs number of MPTCP sockets used.

   - Support mixing IPv4 and IPv6 flows in the in-kernel MPTCP path
     manager.

   - IPv6: don't check net.ipv6.route.max_size and rely on garbage
     collection to free memory (similarly to IPv4).

   - Support Penultimate Segment Pop (PSP) flavor in SRv6 (RFC8986).

   - ICMP: add per-rate limit counters.

   - Add support for user scanning requests in ieee802154.

   - Remove static WEP support.

   - Support minimal Wi-Fi 7 Extremely High Throughput (EHT) rate
     reporting.

   - WiFi 7 EHT channel puncturing support (client & AP).

  BPF:

   - Add a rbtree data structure following the "next-gen data structure"
     precedent set by recently added linked list, that is, by using
     kfunc + kptr instead of adding a new BPF map type.

   - Expose XDP hints via kfuncs with initial support for RX hash and
     timestamp metadata.

   - Add BPF_F_NO_TUNNEL_KEY extension to bpf_skb_set_tunnel_key to
     better support decap on GRE tunnel devices not operating in collect
     metadata.

   - Improve x86 JIT's codegen for PROBE_MEM runtime error checks.

   - Remove the need for trace_printk_lock for bpf_trace_printk and
     bpf_trace_vprintk helpers.

   - Extend libbpf's bpf_tracing.h support for tracing arguments of
     kprobes/uprobes and syscall as a special case.

   - Significantly reduce the search time for module symbols by
     livepatch and BPF.

   - Enable cpumasks to be used as kptrs, which is useful for tracing
     programs tracking which tasks end up running on which CPUs in
     different time intervals.

   - Add support for BPF trampoline on s390x and riscv64.

   - Add capability to export the XDP features supported by the NIC.

   - Add __bpf_kfunc tag for marking kernel functions as kfuncs.

   - Add cgroup.memory=nobpf kernel parameter option to disable BPF
     memory accounting for container environments.

  Netfilter:

   - Remove the CLUSTERIP target. It has been marked as obsolete for
     years, and we still have WARN splats wrt races of the out-of-band
     /proc interface installed by this target.

   - Add 'destroy' commands to nf_tables. They are identical to the
     existing 'delete' commands, but do not return an error if the
     referenced object (set, chain, rule...) did not exist.

  Driver API:

   - Improve cpumask_local_spread() locality to help NICs set the right
     IRQ affinity on AMD platforms.

   - Separate C22 and C45 MDIO bus transactions more clearly.

   - Introduce new DCB table to control DSCP rewrite on egress.

   - Support configuration of Physical Layer Collision Avoidance (PLCA)
     Reconciliation Sublayer (RS) (802.3cg-2019). Modern version of
     shared medium Ethernet.

   - Support for MAC Merge layer (IEEE 802.3-2018 clause 99). Allowing
     preemption of low priority frames by high priority frames.

   - Add support for controlling MACSec offload using netlink SET.

   - Rework devlink instance refcounts to allow registration and
     de-registration under the instance lock. Split the code into
     multiple files, drop some of the unnecessarily granular locks and
     factor out common parts of netlink operation handling.

   - Add TX frame aggregation parameters (for USB drivers).

   - Add a new attr TCA_EXT_WARN_MSG to report TC (offload) warning
     messages with notifications for debug.

   - Allow offloading of UDP NEW connections via act_ct.

   - Add support for per action HW stats in TC.

   - Support hardware miss to TC action (continue processing in SW from
     a specific point in the action chain).

   - Warn if old Wireless Extension user space interface is used with
     modern cfg80211/mac80211 drivers. Do not support Wireless
     Extensions for Wi-Fi 7 devices at all. Everyone should switch to
     using nl80211 interface instead.

   - Improve the CAN bit timing configuration. Use extack to return
     error messages directly to user space, update the SJW handling,
     including the definition of a new default value that will benefit
     CAN-FD controllers, by increasing their oscillator tolerance.

  New hardware / drivers:

   - Ethernet:
      - nVidia BlueField-3 support (control traffic driver)
      - Ethernet support for imx93 SoCs
      - Motorcomm yt8531 gigabit Ethernet PHY
      - onsemi NCN26000 10BASE-T1S PHY (with support for PLCA)
      - Microchip LAN8841 PHY (incl. cable diagnostics and PTP)
      - Amlogic gxl MDIO mux

   - WiFi:
      - RealTek RTL8188EU (rtl8xxxu)
      - Qualcomm Wi-Fi 7 devices (ath12k)

   - CAN:
      - Renesas R-Car V4H

  Drivers:

   - Bluetooth:
      - Set Per Platform Antenna Gain (PPAG) for Intel controllers.

   - Ethernet NICs:
      - Intel (1G, igc):
         - support TSN / Qbv / packet scheduling features of i226 model
      - Intel (100G, ice):
         - use GNSS subsystem instead of TTY
         - multi-buffer XDP support
         - extend support for GPIO pins to E823 devices
      - nVidia/Mellanox:
         - update the shared buffer configuration on PFC commands
         - implement PTP adjphase function for HW offset control
         - TC support for Geneve and GRE with VF tunnel offload
         - more efficient crypto key management method
         - multi-port eswitch support
      - Netronome/Corigine:
         - add DCB IEEE support
         - support IPsec offloading for NFP3800
      - Freescale/NXP (enetc):
         - support XDP_REDIRECT for XDP non-linear buffers
         - improve reconfig, avoid link flap and waiting for idle
         - support MAC Merge layer
      - Other NICs:
         - sfc/ef100: add basic devlink support for ef100
         - ionic: rx_push mode operation (writing descriptors via MMIO)
         - bnxt: use the auxiliary bus abstraction for RDMA
         - r8169: disable ASPM and reset bus in case of tx timeout
         - cpsw: support QSGMII mode for J721e CPSW9G
         - cpts: support pulse-per-second output
         - ngbe: add an mdio bus driver
         - usbnet: optimize usbnet_bh() by avoiding unnecessary queuing
         - r8152: handle devices with FW with NCM support
         - amd-xgbe: support 10Mbps, 2.5GbE speeds and rx-adaptation
         - virtio-net: support multi buffer XDP
         - virtio/vsock: replace virtio_vsock_pkt with sk_buff
         - tsnep: XDP support

   - Ethernet high-speed switches:
      - nVidia/Mellanox (mlxsw):
         - add support for latency TLV (in FW control messages)
      - Microchip (sparx5):
         - separate explicit and implicit traffic forwarding rules, make
           the implicit rules always active
         - add support for egress DSCP rewrite
         - IS0 VCAP support (Ingress Classification)
         - IS2 VCAP filters (protos, L3 addrs, L4 ports, flags, ToS
           etc.)
         - ES2 VCAP support (Egress Access Control)
         - support for Per-Stream Filtering and Policing (802.1Q,
           8.6.5.1)

   - Ethernet embedded switches:
      - Marvell (mv88e6xxx):
         - add MAB (port auth) offload support
         - enable PTP receive for mv88e6390
      - NXP (ocelot):
         - support MAC Merge layer
         - support for the the vsc7512 internal copper phys
      - Microchip:
         - lan9303: convert to PHYLINK
         - lan966x: support TC flower filter statistics
         - lan937x: PTP support for KSZ9563/KSZ8563 and LAN937x
         - lan937x: support Credit Based Shaper configuration
         - ksz9477: support Energy Efficient Ethernet
      - other:
         - qca8k: convert to regmap read/write API, use bulk operations
         - rswitch: Improve TX timestamp accuracy

   - Intel WiFi (iwlwifi):
      - EHT (Wi-Fi 7) rate reporting
      - STEP equalizer support: transfer some STEP (connection to radio
        on platforms with integrated wifi) related parameters from the
        BIOS to the firmware.

   - Qualcomm 802.11ax WiFi (ath11k):
      - IPQ5018 support
      - Fine Timing Measurement (FTM) responder role support
      - channel 177 support

   - MediaTek WiFi (mt76):
      - per-PHY LED support
      - mt7996: EHT (Wi-Fi 7) support
      - Wireless Ethernet Dispatch (WED) reset support
      - switch to using page pool allocator

   - RealTek WiFi (rtw89):
      - support new version of Bluetooth co-existance

   - Mobile:
      - rmnet: support TX aggregation"

* tag 'net-next-6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next: (1872 commits)
  page_pool: add a comment explaining the fragment counter usage
  net: ethtool: fix __ethtool_dev_mm_supported() implementation
  ethtool: pse-pd: Fix double word in comments
  xsk: add linux/vmalloc.h to xsk.c
  sefltests: netdevsim: wait for devlink instance after netns removal
  selftest: fib_tests: Always cleanup before exit
  net/mlx5e: Align IPsec ASO result memory to be as required by hardware
  net/mlx5e: TC, Set CT miss to the specific ct action instance
  net/mlx5e: Rename CHAIN_TO_REG to MAPPED_OBJ_TO_REG
  net/mlx5: Refactor tc miss handling to a single function
  net/mlx5: Kconfig: Make tc offload depend on tc skb extension
  net/sched: flower: Support hardware miss to tc action
  net/sched: flower: Move filter handle initialization earlier
  net/sched: cls_api: Support hardware miss to tc action
  net/sched: Rename user cookie and act cookie
  sfc: fix builds without CONFIG_RTC_LIB
  sfc: clean up some inconsistent indentings
  net/mlx4_en: Introduce flexible array to silence overflow warning
  net: lan966x: Fix possible deadlock inside PTP
  net/ulp: Remove redundant ->clone() test in inet_clone_ulp().
  ...

1 files changed, 535 insertions, 0 deletions

diff --git a/include/net/udp.h b/include/net/udp.h
new file mode 100644
index 000000000..de4b52852
--- /dev/null
+++ b/include/net/udp.h
@@ -0,0 +1,535 @@
+/* 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.
+ *
+ *		Definitions for the UDP module.
+ *
+ * Version:	@(#)udp.h	1.0.2	05/07/93
+ *
+ * Authors:	Ross Biro
+ *		Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
+ *
+ * Fixes:
+ *		Alan Cox	: Turned on udp checksums. I don't want to
+ *				  chase 'memory corruption' bugs that aren't!
+ */
+#ifndef _UDP_H
+#define _UDP_H
+
+#include <linux/list.h>
+#include <linux/bug.h>
+#include <net/inet_sock.h>
+#include <net/sock.h>
+#include <net/snmp.h>
+#include <net/ip.h>
+#include <linux/ipv6.h>
+#include <linux/seq_file.h>
+#include <linux/poll.h>
+#include <linux/indirect_call_wrapper.h>
+
+/**
+ *	struct udp_skb_cb  -  UDP(-Lite) private variables
+ *
+ *	@header:      private variables used by IPv4/IPv6
+ *	@cscov:       checksum coverage length (UDP-Lite only)
+ *	@partial_cov: if set indicates partial csum coverage
+ */
+struct udp_skb_cb {
+	union {
+		struct inet_skb_parm	h4;
+#if IS_ENABLED(CONFIG_IPV6)
+		struct inet6_skb_parm	h6;
+#endif
+	} header;
+	__u16		cscov;
+	__u8		partial_cov;
+};
+#define UDP_SKB_CB(__skb)	((struct udp_skb_cb *)((__skb)->cb))
+
+/**
+ *	struct udp_hslot - UDP hash slot
+ *
+ *	@head:	head of list of sockets
+ *	@count:	number of sockets in 'head' list
+ *	@lock:	spinlock protecting changes to head/count
+ */
+struct udp_hslot {
+	struct hlist_head	head;
+	int			count;
+	spinlock_t		lock;
+} __attribute__((aligned(2 * sizeof(long))));
+
+/**
+ *	struct udp_table - UDP table
+ *
+ *	@hash:	hash table, sockets are hashed on (local port)
+ *	@hash2:	hash table, sockets are hashed on (local port, local address)
+ *	@mask:	number of slots in hash tables, minus 1
+ *	@log:	log2(number of slots in hash table)
+ */
+struct udp_table {
+	struct udp_hslot	*hash;
+	struct udp_hslot	*hash2;
+	unsigned int		mask;
+	unsigned int		log;
+};
+extern struct udp_table udp_table;
+void udp_table_init(struct udp_table *, const char *);
+static inline struct udp_hslot *udp_hashslot(struct udp_table *table,
+					     struct net *net, unsigned int num)
+{
+	return &table->hash[udp_hashfn(net, num, table->mask)];
+}
+/*
+ * For secondary hash, net_hash_mix() is performed before calling
+ * udp_hashslot2(), this explains difference with udp_hashslot()
+ */
+static inline struct udp_hslot *udp_hashslot2(struct udp_table *table,
+					      unsigned int hash)
+{
+	return &table->hash2[hash & table->mask];
+}
+
+extern struct proto udp_prot;
+
+extern atomic_long_t udp_memory_allocated;
+DECLARE_PER_CPU(int, udp_memory_per_cpu_fw_alloc);
+
+/* sysctl variables for udp */
+extern long sysctl_udp_mem[3];
+extern int sysctl_udp_rmem_min;
+extern int sysctl_udp_wmem_min;
+
+struct sk_buff;
+
+/*
+ *	Generic checksumming routines for UDP(-Lite) v4 and v6
+ */
+static inline __sum16 __udp_lib_checksum_complete(struct sk_buff *skb)
+{
+	return (UDP_SKB_CB(skb)->cscov == skb->len ?
+		__skb_checksum_complete(skb) :
+		__skb_checksum_complete_head(skb, UDP_SKB_CB(skb)->cscov));
+}
+
+static inline int udp_lib_checksum_complete(struct sk_buff *skb)
+{
+	return !skb_csum_unnecessary(skb) &&
+		__udp_lib_checksum_complete(skb);
+}
+
+/**
+ * 	udp_csum_outgoing  -  compute UDPv4/v6 checksum over fragments
+ * 	@sk: 	socket we are writing to
+ * 	@skb: 	sk_buff containing the filled-in UDP header
+ * 	        (checksum field must be zeroed out)
+ */
+static inline __wsum udp_csum_outgoing(struct sock *sk, struct sk_buff *skb)
+{
+	__wsum csum = csum_partial(skb_transport_header(skb),
+				   sizeof(struct udphdr), 0);
+	skb_queue_walk(&sk->sk_write_queue, skb) {
+		csum = csum_add(csum, skb->csum);
+	}
+	return csum;
+}
+
+static inline __wsum udp_csum(struct sk_buff *skb)
+{
+	__wsum csum = csum_partial(skb_transport_header(skb),
+				   sizeof(struct udphdr), skb->csum);
+
+	for (skb = skb_shinfo(skb)->frag_list; skb; skb = skb->next) {
+		csum = csum_add(csum, skb->csum);
+	}
+	return csum;
+}
+
+static inline __sum16 udp_v4_check(int len, __be32 saddr,
+				   __be32 daddr, __wsum base)
+{
+	return csum_tcpudp_magic(saddr, daddr, len, IPPROTO_UDP, base);
+}
+
+void udp_set_csum(bool nocheck, struct sk_buff *skb,
+		  __be32 saddr, __be32 daddr, int len);
+
+static inline void udp_csum_pull_header(struct sk_buff *skb)
+{
+	if (!skb->csum_valid && skb->ip_summed == CHECKSUM_NONE)
+		skb->csum = csum_partial(skb->data, sizeof(struct udphdr),
+					 skb->csum);
+	skb_pull_rcsum(skb, sizeof(struct udphdr));
+	UDP_SKB_CB(skb)->cscov -= sizeof(struct udphdr);
+}
+
+typedef struct sock *(*udp_lookup_t)(const struct sk_buff *skb, __be16 sport,
+				     __be16 dport);
+
+void udp_v6_early_demux(struct sk_buff *skb);
+INDIRECT_CALLABLE_DECLARE(int udpv6_rcv(struct sk_buff *));
+
+struct sk_buff *__udp_gso_segment(struct sk_buff *gso_skb,
+				  netdev_features_t features, bool is_ipv6);
+
+static inline void udp_lib_init_sock(struct sock *sk)
+{
+	struct udp_sock *up = udp_sk(sk);
+
+	skb_queue_head_init(&up->reader_queue);
+	up->forward_threshold = sk->sk_rcvbuf >> 2;
+	set_bit(SOCK_CUSTOM_SOCKOPT, &sk->sk_socket->flags);
+}
+
+/* hash routines shared between UDPv4/6 and UDP-Litev4/6 */
+static inline int udp_lib_hash(struct sock *sk)
+{
+	BUG();
+	return 0;
+}
+
+void udp_lib_unhash(struct sock *sk);
+void udp_lib_rehash(struct sock *sk, u16 new_hash);
+
+static inline void udp_lib_close(struct sock *sk, long timeout)
+{
+	sk_common_release(sk);
+}
+
+int udp_lib_get_port(struct sock *sk, unsigned short snum,
+		     unsigned int hash2_nulladdr);
+
+u32 udp_flow_hashrnd(void);
+
+static inline __be16 udp_flow_src_port(struct net *net, struct sk_buff *skb,
+				       int min, int max, bool use_eth)
+{
+	u32 hash;
+
+	if (min >= max) {
+		/* Use default range */
+		inet_get_local_port_range(net, &min, &max);
+	}
+
+	hash = skb_get_hash(skb);
+	if (unlikely(!hash)) {
+		if (use_eth) {
+			/* Can't find a normal hash, caller has indicated an
+			 * Ethernet packet so use that to compute a hash.
+			 */
+			hash = jhash(skb->data, 2 * ETH_ALEN,
+				     (__force u32) skb->protocol);
+		} else {
+			/* Can't derive any sort of hash for the packet, set
+			 * to some consistent random value.
+			 */
+			hash = udp_flow_hashrnd();
+		}
+	}
+
+	/* Since this is being sent on the wire obfuscate hash a bit
+	 * to minimize possbility that any useful information to an
+	 * attacker is leaked. Only upper 16 bits are relevant in the
+	 * computation for 16 bit port value.
+	 */
+	hash ^= hash << 16;
+
+	return htons((((u64) hash * (max - min)) >> 32) + min);
+}
+
+static inline int udp_rqueue_get(struct sock *sk)
+{
+	return sk_rmem_alloc_get(sk) - READ_ONCE(udp_sk(sk)->forward_deficit);
+}
+
+static inline bool udp_sk_bound_dev_eq(struct net *net, int bound_dev_if,
+				       int dif, int sdif)
+{
+#if IS_ENABLED(CONFIG_NET_L3_MASTER_DEV)
+	return inet_bound_dev_eq(!!READ_ONCE(net->ipv4.sysctl_udp_l3mdev_accept),
+				 bound_dev_if, dif, sdif);
+#else
+	return inet_bound_dev_eq(true, bound_dev_if, dif, sdif);
+#endif
+}
+
+/* net/ipv4/udp.c */
+void udp_destruct_common(struct sock *sk);
+void skb_consume_udp(struct sock *sk, struct sk_buff *skb, int len);
+int __udp_enqueue_schedule_skb(struct sock *sk, struct sk_buff *skb);
+void udp_skb_destructor(struct sock *sk, struct sk_buff *skb);
+struct sk_buff *__skb_recv_udp(struct sock *sk, unsigned int flags, int *off,
+			       int *err);
+static inline struct sk_buff *skb_recv_udp(struct sock *sk, unsigned int flags,
+					   int *err)
+{
+	int off = 0;
+
+	return __skb_recv_udp(sk, flags, &off, err);
+}
+
+int udp_v4_early_demux(struct sk_buff *skb);
+bool udp_sk_rx_dst_set(struct sock *sk, struct dst_entry *dst);
+int udp_get_port(struct sock *sk, unsigned short snum,
+		 int (*saddr_cmp)(const struct sock *,
+				  const struct sock *));
+int udp_err(struct sk_buff *, u32);
+int udp_abort(struct sock *sk, int err);
+int udp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len);
+int udp_push_pending_frames(struct sock *sk);
+void udp_flush_pending_frames(struct sock *sk);
+int udp_cmsg_send(struct sock *sk, struct msghdr *msg, u16 *gso_size);
+void udp4_hwcsum(struct sk_buff *skb, __be32 src, __be32 dst);
+int udp_rcv(struct sk_buff *skb);
+int udp_ioctl(struct sock *sk, int cmd, unsigned long arg);
+int udp_init_sock(struct sock *sk);
+int udp_pre_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len);
+int __udp_disconnect(struct sock *sk, int flags);
+int udp_disconnect(struct sock *sk, int flags);
+__poll_t udp_poll(struct file *file, struct socket *sock, poll_table *wait);
+struct sk_buff *skb_udp_tunnel_segment(struct sk_buff *skb,
+				       netdev_features_t features,
+				       bool is_ipv6);
+int udp_lib_getsockopt(struct sock *sk, int level, int optname,
+		       char __user *optval, int __user *optlen);
+int udp_lib_setsockopt(struct sock *sk, int level, int optname,
+		       sockptr_t optval, unsigned int optlen,
+		       int (*push_pending_frames)(struct sock *));
+struct sock *udp4_lib_lookup(struct net *net, __be32 saddr, __be16 sport,
+			     __be32 daddr, __be16 dport, int dif);
+struct sock *__udp4_lib_lookup(struct net *net, __be32 saddr, __be16 sport,
+			       __be32 daddr, __be16 dport, int dif, int sdif,
+			       struct udp_table *tbl, struct sk_buff *skb);
+struct sock *udp4_lib_lookup_skb(const struct sk_buff *skb,
+				 __be16 sport, __be16 dport);
+struct sock *udp6_lib_lookup(struct net *net,
+			     const struct in6_addr *saddr, __be16 sport,
+			     const struct in6_addr *daddr, __be16 dport,
+			     int dif);
+struct sock *__udp6_lib_lookup(struct net *net,
+			       const struct in6_addr *saddr, __be16 sport,
+			       const struct in6_addr *daddr, __be16 dport,
+			       int dif, int sdif, struct udp_table *tbl,
+			       struct sk_buff *skb);
+struct sock *udp6_lib_lookup_skb(const struct sk_buff *skb,
+				 __be16 sport, __be16 dport);
+int udp_read_skb(struct sock *sk, skb_read_actor_t recv_actor);
+
+/* UDP uses skb->dev_scratch to cache as much information as possible and avoid
+ * possibly multiple cache miss on dequeue()
+ */
+struct udp_dev_scratch {
+	/* skb->truesize and the stateless bit are embedded in a single field;
+	 * do not use a bitfield since the compiler emits better/smaller code
+	 * this way
+	 */
+	u32 _tsize_state;
+
+#if BITS_PER_LONG == 64
+	/* len and the bit needed to compute skb_csum_unnecessary
+	 * will be on cold cache lines at recvmsg time.
+	 * skb->len can be stored on 16 bits since the udp header has been
+	 * already validated and pulled.
+	 */
+	u16 len;
+	bool is_linear;
+	bool csum_unnecessary;
+#endif
+};
+
+static inline struct udp_dev_scratch *udp_skb_scratch(struct sk_buff *skb)
+{
+	return (struct udp_dev_scratch *)&skb->dev_scratch;
+}
+
+#if BITS_PER_LONG == 64
+static inline unsigned int udp_skb_len(struct sk_buff *skb)
+{
+	return udp_skb_scratch(skb)->len;
+}
+
+static inline bool udp_skb_csum_unnecessary(struct sk_buff *skb)
+{
+	return udp_skb_scratch(skb)->csum_unnecessary;
+}
+
+static inline bool udp_skb_is_linear(struct sk_buff *skb)
+{
+	return udp_skb_scratch(skb)->is_linear;
+}
+
+#else
+static inline unsigned int udp_skb_len(struct sk_buff *skb)
+{
+	return skb->len;
+}
+
+static inline bool udp_skb_csum_unnecessary(struct sk_buff *skb)
+{
+	return skb_csum_unnecessary(skb);
+}
+
+static inline bool udp_skb_is_linear(struct sk_buff *skb)
+{
+	return !skb_is_nonlinear(skb);
+}
+#endif
+
+static inline int copy_linear_skb(struct sk_buff *skb, int len, int off,
+				  struct iov_iter *to)
+{
+	int n;
+
+	n = copy_to_iter(skb->data + off, len, to);
+	if (n == len)
+		return 0;
+
+	iov_iter_revert(to, n);
+	return -EFAULT;
+}
+
+/*
+ * 	SNMP statistics for UDP and UDP-Lite
+ */
+#define UDP_INC_STATS(net, field, is_udplite)		      do { \
+	if (is_udplite) SNMP_INC_STATS((net)->mib.udplite_statistics, field);       \
+	else		SNMP_INC_STATS((net)->mib.udp_statistics, field);  }  while(0)
+#define __UDP_INC_STATS(net, field, is_udplite) 	      do { \
+	if (is_udplite) __SNMP_INC_STATS((net)->mib.udplite_statistics, field);         \
+	else		__SNMP_INC_STATS((net)->mib.udp_statistics, field);    }  while(0)
+
+#define __UDP6_INC_STATS(net, field, is_udplite)	    do { \
+	if (is_udplite) __SNMP_INC_STATS((net)->mib.udplite_stats_in6, field);\
+	else		__SNMP_INC_STATS((net)->mib.udp_stats_in6, field);  \
+} while(0)
+#define UDP6_INC_STATS(net, field, __lite)		    do { \
+	if (__lite) SNMP_INC_STATS((net)->mib.udplite_stats_in6, field);  \
+	else	    SNMP_INC_STATS((net)->mib.udp_stats_in6, field);      \
+} while(0)
+
+#if IS_ENABLED(CONFIG_IPV6)
+#define __UDPX_MIB(sk, ipv4)						\
+({									\
+	ipv4 ? (IS_UDPLITE(sk) ? sock_net(sk)->mib.udplite_statistics :	\
+				 sock_net(sk)->mib.udp_statistics) :	\
+		(IS_UDPLITE(sk) ? sock_net(sk)->mib.udplite_stats_in6 :	\
+				 sock_net(sk)->mib.udp_stats_in6);	\
+})
+#else
+#define __UDPX_MIB(sk, ipv4)						\
+({									\
+	IS_UDPLITE(sk) ? sock_net(sk)->mib.udplite_statistics :		\
+			 sock_net(sk)->mib.udp_statistics;		\
+})
+#endif
+
+#define __UDPX_INC_STATS(sk, field) \
+	__SNMP_INC_STATS(__UDPX_MIB(sk, (sk)->sk_family == AF_INET), field)
+
+#ifdef CONFIG_PROC_FS
+struct udp_seq_afinfo {
+	sa_family_t			family;
+	struct udp_table		*udp_table;
+};
+
+struct udp_iter_state {
+	struct seq_net_private  p;
+	int			bucket;
+	struct udp_seq_afinfo	*bpf_seq_afinfo;
+};
+
+void *udp_seq_start(struct seq_file *seq, loff_t *pos);
+void *udp_seq_next(struct seq_file *seq, void *v, loff_t *pos);
+void udp_seq_stop(struct seq_file *seq, void *v);
+
+extern const struct seq_operations udp_seq_ops;
+extern const struct seq_operations udp6_seq_ops;
+
+int udp4_proc_init(void);
+void udp4_proc_exit(void);
+#endif /* CONFIG_PROC_FS */
+
+int udpv4_offload_init(void);
+
+void udp_init(void);
+
+DECLARE_STATIC_KEY_FALSE(udp_encap_needed_key);
+void udp_encap_enable(void);
+void udp_encap_disable(void);
+#if IS_ENABLED(CONFIG_IPV6)
+DECLARE_STATIC_KEY_FALSE(udpv6_encap_needed_key);
+void udpv6_encap_enable(void);
+#endif
+
+static inline struct sk_buff *udp_rcv_segment(struct sock *sk,
+					      struct sk_buff *skb, bool ipv4)
+{
+	netdev_features_t features = NETIF_F_SG;
+	struct sk_buff *segs;
+
+	/* Avoid csum recalculation by skb_segment unless userspace explicitly
+	 * asks for the final checksum values
+	 */
+	if (!inet_get_convert_csum(sk))
+		features |= NETIF_F_IP_CSUM | NETIF_F_IPV6_CSUM;
+
+	/* UDP segmentation expects packets of type CHECKSUM_PARTIAL or
+	 * CHECKSUM_NONE in __udp_gso_segment. UDP GRO indeed builds partial
+	 * packets in udp_gro_complete_segment. As does UDP GSO, verified by
+	 * udp_send_skb. But when those packets are looped in dev_loopback_xmit
+	 * their ip_summed CHECKSUM_NONE is changed to CHECKSUM_UNNECESSARY.
+	 * Reset in this specific case, where PARTIAL is both correct and
+	 * required.
+	 */
+	if (skb->pkt_type == PACKET_LOOPBACK)
+		skb->ip_summed = CHECKSUM_PARTIAL;
+
+	/* the GSO CB lays after the UDP one, no need to save and restore any
+	 * CB fragment
+	 */
+	segs = __skb_gso_segment(skb, features, false);
+	if (IS_ERR_OR_NULL(segs)) {
+		int segs_nr = skb_shinfo(skb)->gso_segs;
+
+		atomic_add(segs_nr, &sk->sk_drops);
+		SNMP_ADD_STATS(__UDPX_MIB(sk, ipv4), UDP_MIB_INERRORS, segs_nr);
+		kfree_skb(skb);
+		return NULL;
+	}
+
+	consume_skb(skb);
+	return segs;
+}
+
+static inline void udp_post_segment_fix_csum(struct sk_buff *skb)
+{
+	/* UDP-lite can't land here - no GRO */
+	WARN_ON_ONCE(UDP_SKB_CB(skb)->partial_cov);
+
+	/* UDP packets generated with UDP_SEGMENT and traversing:
+	 *
+	 * UDP tunnel(xmit) -> veth (segmentation) -> veth (gro) -> UDP tunnel (rx)
+	 *
+	 * can reach an UDP socket with CHECKSUM_NONE, because
+	 * __iptunnel_pull_header() converts CHECKSUM_PARTIAL into NONE.
+	 * SKB_GSO_UDP_L4 or SKB_GSO_FRAGLIST packets with no UDP tunnel will
+	 * have a valid checksum, as the GRO engine validates the UDP csum
+	 * before the aggregation and nobody strips such info in between.
+	 * Instead of adding another check in the tunnel fastpath, we can force
+	 * a valid csum after the segmentation.
+	 * Additionally fixup the UDP CB.
+	 */
+	UDP_SKB_CB(skb)->cscov = skb->len;
+	if (skb->ip_summed == CHECKSUM_NONE && !skb->csum_valid)
+		skb->csum_valid = 1;
+}
+
+#ifdef CONFIG_BPF_SYSCALL
+struct sk_psock;
+struct proto *udp_bpf_get_proto(struct sock *sk, struct sk_psock *psock);
+int udp_bpf_update_proto(struct sock *sk, struct sk_psock *psock, bool restore);
+#endif
+
+#endif	/* _UDP_H */