/* 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;

/* 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);

INDIRECT_CALLABLE_DECLARE(struct sk_buff *udp4_gro_receive(struct list_head *,
                                                           struct sk_buff *));
INDIRECT_CALLABLE_DECLARE(int udp4_gro_complete(struct sk_buff *, int));
INDIRECT_CALLABLE_DECLARE(struct sk_buff *udp6_gro_receive(struct list_head *,
                                                           struct sk_buff *));
INDIRECT_CALLABLE_DECLARE(int udp6_gro_complete(struct sk_buff *, int));
INDIRECT_CALLABLE_DECLARE(void udp_v6_early_demux(struct sk_buff *));
INDIRECT_CALLABLE_DECLARE(int udpv6_rcv(struct sk_buff *));

struct sk_buff *udp_gro_receive(struct list_head *head, struct sk_buff *skb,
                                struct udphdr *uh, struct sock *sk);
int udp_gro_complete(struct sk_buff *skb, int nhoff, udp_lookup_t lookup);

struct sk_buff *__udp_gso_segment(struct sk_buff *gso_skb,
                                  netdev_features_t features, bool is_ipv6);

static inline struct udphdr *udp_gro_udphdr(struct sk_buff *skb)
{
        struct udphdr *uh;
        unsigned int hlen, off;

        off  = skb_gro_offset(skb);
        hlen = off + sizeof(*uh);
        uh   = skb_gro_header_fast(skb, off);
        if (skb_gro_header_hard(skb, hlen))
                uh = skb_gro_header_slow(skb, hlen, off);

        return uh;
}

/* 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(!!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_sock(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 noblock, int *off, int *err);
static inline struct sk_buff *skb_recv_udp(struct sock *sk, unsigned int flags,
                                           int noblock, int *err)
{
        int off = 0;

        return __skb_recv_udp(sk, flags, noblock, &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_sock(struct sock *sk, read_descriptor_t *desc,
                  sk_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 */