// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *	RAW sockets for IPv6
 *	Linux INET6 implementation
 *
 *	Authors:
 *	Pedro Roque		<roque@di.fc.ul.pt>
 *
 *	Adapted from linux/net/ipv4/raw.c
 *
 *	Fixes:
 *	Hideaki YOSHIFUJI	:	sin6_scope_id support
 *	YOSHIFUJI,H.@USAGI	:	raw checksum (RFC2292(bis) compliance)
 *	Kazunori MIYAZAWA @USAGI:	change process style to use ip6_append_data
 */

#include <linux/errno.h>
#include <linux/types.h>
#include <linux/socket.h>
#include <linux/slab.h>
#include <linux/sockios.h>
#include <linux/net.h>
#include <linux/in6.h>
#include <linux/netdevice.h>
#include <linux/if_arp.h>
#include <linux/icmpv6.h>
#include <linux/netfilter.h>
#include <linux/netfilter_ipv6.h>
#include <linux/skbuff.h>
#include <linux/compat.h>
#include <linux/uaccess.h>
#include <asm/ioctls.h>

#include <net/net_namespace.h>
#include <net/ip.h>
#include <net/sock.h>
#include <net/snmp.h>

#include <net/ipv6.h>
#include <net/ndisc.h>
#include <net/protocol.h>
#include <net/ip6_route.h>
#include <net/ip6_checksum.h>
#include <net/addrconf.h>
#include <net/transp_v6.h>
#include <net/udp.h>
#include <net/inet_common.h>
#include <net/tcp_states.h>
#if IS_ENABLED(CONFIG_IPV6_MIP6)
#include <net/mip6.h>
#endif
#include <linux/mroute6.h>

#include <net/raw.h>
#include <net/rawv6.h>
#include <net/xfrm.h>

#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <linux/export.h>

#define	ICMPV6_HDRLEN	4	/* ICMPv6 header, RFC 4443 Section 2.1 */

struct raw_hashinfo raw_v6_hashinfo = {
	.lock = __RW_LOCK_UNLOCKED(raw_v6_hashinfo.lock),
};
EXPORT_SYMBOL_GPL(raw_v6_hashinfo);

struct sock *__raw_v6_lookup(struct net *net, struct sock *sk,
		unsigned short num, const struct in6_addr *loc_addr,
		const struct in6_addr *rmt_addr, int dif, int sdif)
{
	bool is_multicast = ipv6_addr_is_multicast(loc_addr);

	sk_for_each_from(sk)
		if (inet_sk(sk)->inet_num == num) {

			if (!net_eq(sock_net(sk), net))
				continue;

			if (!ipv6_addr_any(&sk->sk_v6_daddr) &&
			    !ipv6_addr_equal(&sk->sk_v6_daddr, rmt_addr))
				continue;

			if (!raw_sk_bound_dev_eq(net, sk->sk_bound_dev_if,
						 dif, sdif))
				continue;

			if (!ipv6_addr_any(&sk->sk_v6_rcv_saddr)) {
				if (ipv6_addr_equal(&sk->sk_v6_rcv_saddr, loc_addr))
					goto found;
				if (is_multicast &&
				    inet6_mc_check(sk, loc_addr, rmt_addr))
					goto found;
				continue;
			}
			goto found;
		}
	sk = NULL;
found:
	return sk;
}
EXPORT_SYMBOL_GPL(__raw_v6_lookup);

/*
 *	0 - deliver
 *	1 - block
 */
static int icmpv6_filter(const struct sock *sk, const struct sk_buff *skb)
{
	struct icmp6hdr _hdr;
	const struct icmp6hdr *hdr;

	/* We require only the four bytes of the ICMPv6 header, not any
	 * additional bytes of message body in "struct icmp6hdr".
	 */
	hdr = skb_header_pointer(skb, skb_transport_offset(skb),
				 ICMPV6_HDRLEN, &_hdr);
	if (hdr) {
		const __u32 *data = &raw6_sk(sk)->filter.data[0];
		unsigned int type = hdr->icmp6_type;

		return (data[type >> 5] & (1U << (type & 31))) != 0;
	}
	return 1;
}

#if IS_ENABLED(CONFIG_IPV6_MIP6)
typedef int mh_filter_t(struct sock *sock, struct sk_buff *skb);

static mh_filter_t __rcu *mh_filter __read_mostly;

int rawv6_mh_filter_register(mh_filter_t filter)
{
	rcu_assign_pointer(mh_filter, filter);
	return 0;
}
EXPORT_SYMBOL(rawv6_mh_filter_register);

int rawv6_mh_filter_unregister(mh_filter_t filter)
{
	RCU_INIT_POINTER(mh_filter, NULL);
	synchronize_rcu();
	return 0;
}
EXPORT_SYMBOL(rawv6_mh_filter_unregister);

#endif

/*
 *	demultiplex raw sockets.
 *	(should consider queueing the skb in the sock receive_queue
 *	without calling rawv6.c)
 *
 *	Caller owns SKB so we must make clones.
 */
static bool ipv6_raw_deliver(struct sk_buff *skb, int nexthdr)
{
	const struct in6_addr *saddr;
	const struct in6_addr *daddr;
	struct sock *sk;
	bool delivered = false;
	__u8 hash;
	struct net *net;

	saddr = &ipv6_hdr(skb)->saddr;
	daddr = saddr + 1;

	hash = nexthdr & (RAW_HTABLE_SIZE - 1);

	read_lock(&raw_v6_hashinfo.lock);
	sk = sk_head(&raw_v6_hashinfo.ht[hash]);

	if (!sk)
		goto out;

	net = dev_net(skb->dev);
	sk = __raw_v6_lookup(net, sk, nexthdr, daddr, saddr,
			     inet6_iif(skb), inet6_sdif(skb));

	while (sk) {
		int filtered;

		delivered = true;
		switch (nexthdr) {
		case IPPROTO_ICMPV6:
			filtered = icmpv6_filter(sk, skb);
			break;

#if IS_ENABLED(CONFIG_IPV6_MIP6)
		case IPPROTO_MH:
		{
			/* XXX: To validate MH only once for each packet,
			 * this is placed here. It should be after checking
			 * xfrm policy, however it doesn't. The checking xfrm
			 * policy is placed in rawv6_rcv() because it is
			 * required for each socket.
			 */
			mh_filter_t *filter;

			filter = rcu_dereference(mh_filter);
			filtered = filter ? (*filter)(sk, skb) : 0;
			break;
		}
#endif
		default:
			filtered = 0;
			break;
		}

		if (filtered < 0)
			break;
		if (filtered == 0) {
			struct sk_buff *clone = skb_clone(skb, GFP_ATOMIC);

			/* Not releasing hash table! */
			if (clone) {
				nf_reset_ct(clone);
				rawv6_rcv(sk, clone);
			}
		}
		sk = __raw_v6_lookup(net, sk_next(sk), nexthdr, daddr, saddr,
				     inet6_iif(skb), inet6_sdif(skb));
	}
out:
	read_unlock(&raw_v6_hashinfo.lock);
	return delivered;
}

bool raw6_local_deliver(struct sk_buff *skb, int nexthdr)
{
	struct sock *raw_sk;

	raw_sk = sk_head(&raw_v6_hashinfo.ht[nexthdr & (RAW_HTABLE_SIZE - 1)]);
	if (raw_sk && !ipv6_raw_deliver(skb, nexthdr))
		raw_sk = NULL;

	return raw_sk != NULL;
}

/* This cleans up af_inet6 a bit. -DaveM */
static int rawv6_bind(struct sock *sk, struct sockaddr *uaddr, int addr_len)
{
	struct inet_sock *inet = inet_sk(sk);
	struct ipv6_pinfo *np = inet6_sk(sk);
	struct sockaddr_in6 *addr = (struct sockaddr_in6 *) uaddr;
	__be32 v4addr = 0;
	int addr_type;
	int err;

	if (addr_len < SIN6_LEN_RFC2133)
		return -EINVAL;

	if (addr->sin6_family != AF_INET6)
		return -EINVAL;

	addr_type = ipv6_addr_type(&addr->sin6_addr);

	/* Raw sockets are IPv6 only */
	if (addr_type == IPV6_ADDR_MAPPED)
		return -EADDRNOTAVAIL;

	lock_sock(sk);

	err = -EINVAL;
	if (sk->sk_state != TCP_CLOSE)
		goto out;

	rcu_read_lock();
	/* Check if the address belongs to the host. */
	if (addr_type != IPV6_ADDR_ANY) {
		struct net_device *dev = NULL;

		if (__ipv6_addr_needs_scope_id(addr_type)) {
			if (addr_len >= sizeof(struct sockaddr_in6) &&
			    addr->sin6_scope_id) {
				/* Override any existing binding, if another
				 * one is supplied by user.
				 */
				sk->sk_bound_dev_if = addr->sin6_scope_id;
			}

			/* Binding to link-local address requires an interface */
			if (!sk->sk_bound_dev_if)
				goto out_unlock;
		}

		if (sk->sk_bound_dev_if) {
			err = -ENODEV;
			dev = dev_get_by_index_rcu(sock_net(sk),
						   sk->sk_bound_dev_if);
			if (!dev)
				goto out_unlock;
		}

		/* ipv4 addr of the socket is invalid.  Only the
		 * unspecified and mapped address have a v4 equivalent.
		 */
		v4addr = LOOPBACK4_IPV6;
		if (!(addr_type & IPV6_ADDR_MULTICAST) &&
		    !ipv6_can_nonlocal_bind(sock_net(sk), inet)) {
			err = -EADDRNOTAVAIL;
			if (!ipv6_chk_addr(sock_net(sk), &addr->sin6_addr,
					   dev, 0)) {
				goto out_unlock;
			}
		}
	}

	inet->inet_rcv_saddr = inet->inet_saddr = v4addr;
	sk->sk_v6_rcv_saddr = addr->sin6_addr;
	if (!(addr_type & IPV6_ADDR_MULTICAST))
		np->saddr = addr->sin6_addr;
	err = 0;
out_unlock:
	rcu_read_unlock();
out:
	release_sock(sk);
	return err;
}

static void rawv6_err(struct sock *sk, struct sk_buff *skb,
	       struct inet6_skb_parm *opt,
	       u8 type, u8 code, int offset, __be32 info)
{
	struct inet_sock *inet = inet_sk(sk);
	struct ipv6_pinfo *np = inet6_sk(sk);
	int err;
	int harderr;

	/* Report error on raw socket, if:
	   1. User requested recverr.
	   2. Socket is connected (otherwise the error indication
	      is useless without recverr and error is hard.
	 */
	if (!np->recverr && sk->sk_state != TCP_ESTABLISHED)
		return;

	harderr = icmpv6_err_convert(type, code, &err);
	if (type == ICMPV6_PKT_TOOBIG) {
		ip6_sk_update_pmtu(skb, sk, info);
		harderr = (np->pmtudisc == IPV6_PMTUDISC_DO);
	}
	if (type == NDISC_REDIRECT) {
		ip6_sk_redirect(skb, sk);
		return;
	}
	if (np->recverr) {
		u8 *payload = skb->data;
		if (!inet->hdrincl)
			payload += offset;
		ipv6_icmp_error(sk, skb, err, 0, ntohl(info), payload);
	}

	if (np->recverr || harderr) {
		sk->sk_err = err;
		sk_error_report(sk);
	}
}

void raw6_icmp_error(struct sk_buff *skb, int nexthdr,
		u8 type, u8 code, int inner_offset, __be32 info)
{
	struct sock *sk;
	int hash;
	const struct in6_addr *saddr, *daddr;
	struct net *net;

	hash = nexthdr & (RAW_HTABLE_SIZE - 1);

	read_lock(&raw_v6_hashinfo.lock);
	sk = sk_head(&raw_v6_hashinfo.ht[hash]);
	if (sk) {
		/* Note: ipv6_hdr(skb) != skb->data */
		const struct ipv6hdr *ip6h = (const struct ipv6hdr *)skb->data;
		saddr = &ip6h->saddr;
		daddr = &ip6h->daddr;
		net = dev_net(skb->dev);

		while ((sk = __raw_v6_lookup(net, sk, nexthdr, saddr, daddr,
					     inet6_iif(skb), inet6_iif(skb)))) {
			rawv6_err(sk, skb, NULL, type, code,
					inner_offset, info);
			sk = sk_next(sk);
		}
	}
	read_unlock(&raw_v6_hashinfo.lock);
}

static inline int rawv6_rcv_skb(struct sock *sk, struct sk_buff *skb)
{
	if ((raw6_sk(sk)->checksum || rcu_access_pointer(sk->sk_filter)) &&
	    skb_checksum_complete(skb)) {
		atomic_inc(&sk->sk_drops);
		kfree_skb(skb);
		return NET_RX_DROP;
	}

	/* Charge it to the socket. */
	skb_dst_drop(skb);
	if (sock_queue_rcv_skb(sk, skb) < 0) {
		kfree_skb(skb);
		return NET_RX_DROP;
	}

	return 0;
}

/*
 *	This is next to useless...
 *	if we demultiplex in network layer we don't need the extra call
 *	just to queue the skb...
 *	maybe we could have the network decide upon a hint if it
 *	should call raw_rcv for demultiplexing
 */
int rawv6_rcv(struct sock *sk, struct sk_buff *skb)
{
	struct inet_sock *inet = inet_sk(sk);
	struct raw6_sock *rp = raw6_sk(sk);

	if (!xfrm6_policy_check(sk, XFRM_POLICY_IN, skb)) {
		atomic_inc(&sk->sk_drops);
		kfree_skb(skb);
		return NET_RX_DROP;
	}

	if (!rp->checksum)
		skb->ip_summed = CHECKSUM_UNNECESSARY;

	if (skb->ip_summed == CHECKSUM_COMPLETE) {
		skb_postpull_rcsum(skb, skb_network_header(skb),
				   skb_network_header_len(skb));
		if (!csum_ipv6_magic(&ipv6_hdr(skb)->saddr,
				     &ipv6_hdr(skb)->daddr,
				     skb->len, inet->inet_num, skb->csum))
			skb->ip_summed = CHECKSUM_UNNECESSARY;
	}
	if (!skb_csum_unnecessary(skb))
		skb->csum = ~csum_unfold(csum_ipv6_magic(&ipv6_hdr(skb)->saddr,
							 &ipv6_hdr(skb)->daddr,
							 skb->len,
							 inet->inet_num, 0));

	if (inet->hdrincl) {
		if (skb_checksum_complete(skb)) {
			atomic_inc(&sk->sk_drops);
			kfree_skb(skb);
			return NET_RX_DROP;
		}
	}

	rawv6_rcv_skb(sk, skb);
	return 0;
}


/*
 *	This should be easy, if there is something there
 *	we return it, otherwise we block.
 */

static int rawv6_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
			 int noblock, int flags, int *addr_len)
{
	struct ipv6_pinfo *np = inet6_sk(sk);
	DECLARE_SOCKADDR(struct sockaddr_in6 *, sin6, msg->msg_name);
	struct sk_buff *skb;
	size_t copied;
	int err;

	if (flags & MSG_OOB)
		return -EOPNOTSUPP;

	if (flags & MSG_ERRQUEUE)
		return ipv6_recv_error(sk, msg, len, addr_len);

	if (np->rxpmtu && np->rxopt.bits.rxpmtu)
		return ipv6_recv_rxpmtu(sk, msg, len, addr_len);

	skb = skb_recv_datagram(sk, flags, noblock, &err);
	if (!skb)
		goto out;

	copied = skb->len;
	if (copied > len) {
		copied = len;
		msg->msg_flags |= MSG_TRUNC;
	}

	if (skb_csum_unnecessary(skb)) {
		err = skb_copy_datagram_msg(skb, 0, msg, copied);
	} else if (msg->msg_flags&MSG_TRUNC) {
		if (__skb_checksum_complete(skb))
			goto csum_copy_err;
		err = skb_copy_datagram_msg(skb, 0, msg, copied);
	} else {
		err = skb_copy_and_csum_datagram_msg(skb, 0, msg);
		if (err == -EINVAL)
			goto csum_copy_err;
	}
	if (err)
		goto out_free;

	/* Copy the address. */
	if (sin6) {
		sin6->sin6_family = AF_INET6;
		sin6->sin6_port = 0;
		sin6->sin6_addr = ipv6_hdr(skb)->saddr;
		sin6->sin6_flowinfo = 0;
		sin6->sin6_scope_id = ipv6_iface_scope_id(&sin6->sin6_addr,
							  inet6_iif(skb));
		*addr_len = sizeof(*sin6);
	}

	sock_recv_ts_and_drops(msg, sk, skb);

	if (np->rxopt.all)
		ip6_datagram_recv_ctl(sk, msg, skb);

	err = copied;
	if (flags & MSG_TRUNC)
		err = skb->len;

out_free:
	skb_free_datagram(sk, skb);
out:
	return err;

csum_copy_err:
	skb_kill_datagram(sk, skb, flags);

	/* Error for blocking case is chosen to masquerade
	   as some normal condition.
	 */
	err = (flags&MSG_DONTWAIT) ? -EAGAIN : -EHOSTUNREACH;
	goto out;
}

static int rawv6_push_pending_frames(struct sock *sk, struct flowi6 *fl6,
				     struct raw6_sock *rp)
{
	struct sk_buff *skb;
	int err = 0;
	int offset;
	int len;
	int total_len;
	__wsum tmp_csum;
	__sum16 csum;

	if (!rp->checksum)
		goto send;

	skb = skb_peek(&sk->sk_write_queue);
	if (!skb)
		goto out;

	offset = rp->offset;
	total_len = inet_sk(sk)->cork.base.length;
	if (offset >= total_len - 1) {
		err = -EINVAL;
		ip6_flush_pending_frames(sk);
		goto out;
	}

	/* should be check HW csum miyazawa */
	if (skb_queue_len(&sk->sk_write_queue) == 1) {
		/*
		 * Only one fragment on the socket.
		 */
		tmp_csum = skb->csum;
	} else {
		struct sk_buff *csum_skb = NULL;
		tmp_csum = 0;

		skb_queue_walk(&sk->sk_write_queue, skb) {
			tmp_csum = csum_add(tmp_csum, skb->csum);

			if (csum_skb)
				continue;

			len = skb->len - skb_transport_offset(skb);
			if (offset >= len) {
				offset -= len;
				continue;
			}

			csum_skb = skb;
		}

		skb = csum_skb;
	}

	offset += skb_transport_offset(skb);
	err = skb_copy_bits(skb, offset, &csum, 2);
	if (err < 0) {
		ip6_flush_pending_frames(sk);
		goto out;
	}

	/* in case cksum was not initialized */
	if (unlikely(csum))
		tmp_csum = csum_sub(tmp_csum, csum_unfold(csum));

	csum = csum_ipv6_magic(&fl6->saddr, &fl6->daddr,
			       total_len, fl6->flowi6_proto, tmp_csum);

	if (csum == 0 && fl6->flowi6_proto == IPPROTO_UDP)
		csum = CSUM_MANGLED_0;

	BUG_ON(skb_store_bits(skb, offset, &csum, 2));

send:
	err = ip6_push_pending_frames(sk);
out:
	return err;
}

static int rawv6_send_hdrinc(struct sock *sk, struct msghdr *msg, int length,
			struct flowi6 *fl6, struct dst_entry **dstp,
			unsigned int flags, const struct sockcm_cookie *sockc)
{
	struct ipv6_pinfo *np = inet6_sk(sk);
	struct net *net = sock_net(sk);
	struct ipv6hdr *iph;
	struct sk_buff *skb;
	int err;
	struct rt6_info *rt = (struct rt6_info *)*dstp;
	int hlen = LL_RESERVED_SPACE(rt->dst.dev);
	int tlen = rt->dst.dev->needed_tailroom;

	if (length > rt->dst.dev->mtu) {
		ipv6_local_error(sk, EMSGSIZE, fl6, rt->dst.dev->mtu);
		return -EMSGSIZE;
	}
	if (length < sizeof(struct ipv6hdr))
		return -EINVAL;
	if (flags&MSG_PROBE)
		goto out;

	skb = sock_alloc_send_skb(sk,
				  length + hlen + tlen + 15,
				  flags & MSG_DONTWAIT, &err);
	if (!skb)
		goto error;
	skb_reserve(skb, hlen);

	skb->protocol = htons(ETH_P_IPV6);
	skb->priority = sk->sk_priority;
	skb->mark = sockc->mark;
	skb->tstamp = sockc->transmit_time;

	skb_put(skb, length);
	skb_reset_network_header(skb);
	iph = ipv6_hdr(skb);

	skb->ip_summed = CHECKSUM_NONE;

	skb_setup_tx_timestamp(skb, sockc->tsflags);

	if (flags & MSG_CONFIRM)
		skb_set_dst_pending_confirm(skb, 1);

	skb->transport_header = skb->network_header;
	err = memcpy_from_msg(iph, msg, length);
	if (err) {
		err = -EFAULT;
		kfree_skb(skb);
		goto error;
	}

	skb_dst_set(skb, &rt->dst);
	*dstp = NULL;

	/* if egress device is enslaved to an L3 master device pass the
	 * skb to its handler for processing
	 */
	skb = l3mdev_ip6_out(sk, skb);
	if (unlikely(!skb))
		return 0;

	/* Acquire rcu_read_lock() in case we need to use rt->rt6i_idev
	 * in the error path. Since skb has been freed, the dst could
	 * have been queued for deletion.
	 */
	rcu_read_lock();
	IP6_UPD_PO_STATS(net, rt->rt6i_idev, IPSTATS_MIB_OUT, skb->len);
	err = NF_HOOK(NFPROTO_IPV6, NF_INET_LOCAL_OUT, net, sk, skb,
		      NULL, rt->dst.dev, dst_output);
	if (err > 0)
		err = net_xmit_errno(err);
	if (err) {
		IP6_INC_STATS(net, rt->rt6i_idev, IPSTATS_MIB_OUTDISCARDS);
		rcu_read_unlock();
		goto error_check;
	}
	rcu_read_unlock();
out:
	return 0;

error:
	IP6_INC_STATS(net, rt->rt6i_idev, IPSTATS_MIB_OUTDISCARDS);
error_check:
	if (err == -ENOBUFS && !np->recverr)
		err = 0;
	return err;
}

struct raw6_frag_vec {
	struct msghdr *msg;
	int hlen;
	char c[4];
};

static int rawv6_probe_proto_opt(struct raw6_frag_vec *rfv, struct flowi6 *fl6)
{
	int err = 0;
	switch (fl6->flowi6_proto) {
	case IPPROTO_ICMPV6:
		rfv->hlen = 2;
		err = memcpy_from_msg(rfv->c, rfv->msg, rfv->hlen);
		if (!err) {
			fl6->fl6_icmp_type = rfv->c[0];
			fl6->fl6_icmp_code = rfv->c[1];
		}
		break;
	case IPPROTO_MH:
		rfv->hlen = 4;
		err = memcpy_from_msg(rfv->c, rfv->msg, rfv->hlen);
		if (!err)
			fl6->fl6_mh_type = rfv->c[2];
	}
	return err;
}

static int raw6_getfrag(void *from, char *to, int offset, int len, int odd,
		       struct sk_buff *skb)
{
	struct raw6_frag_vec *rfv = from;

	if (offset < rfv->hlen) {
		int copy = min(rfv->hlen - offset, len);

		if (skb->ip_summed == CHECKSUM_PARTIAL)
			memcpy(to, rfv->c + offset, copy);
		else
			skb->csum = csum_block_add(
				skb->csum,
				csum_partial_copy_nocheck(rfv->c + offset,
							  to, copy),
				odd);

		odd = 0;
		offset += copy;
		to += copy;
		len -= copy;

		if (!len)
			return 0;
	}

	offset -= rfv->hlen;

	return ip_generic_getfrag(rfv->msg, to, offset, len, odd, skb);
}

static int rawv6_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
{
	struct ipv6_txoptions *opt_to_free = NULL;
	struct ipv6_txoptions opt_space;
	DECLARE_SOCKADDR(struct sockaddr_in6 *, sin6, msg->msg_name);
	struct in6_addr *daddr, *final_p, final;
	struct inet_sock *inet = inet_sk(sk);
	struct ipv6_pinfo *np = inet6_sk(sk);
	struct raw6_sock *rp = raw6_sk(sk);
	struct ipv6_txoptions *opt = NULL;
	struct ip6_flowlabel *flowlabel = NULL;
	struct dst_entry *dst = NULL;
	struct raw6_frag_vec rfv;
	struct flowi6 fl6;
	struct ipcm6_cookie ipc6;
	int addr_len = msg->msg_namelen;
	int hdrincl;
	u16 proto;
	int err;

	/* Rough check on arithmetic overflow,
	   better check is made in ip6_append_data().
	 */
	if (len > INT_MAX)
		return -EMSGSIZE;

	/* Mirror BSD error message compatibility */
	if (msg->msg_flags & MSG_OOB)
		return -EOPNOTSUPP;

	/* hdrincl should be READ_ONCE(inet->hdrincl)
	 * but READ_ONCE() doesn't work with bit fields.
	 * Doing this indirectly yields the same result.
	 */
	hdrincl = inet->hdrincl;
	hdrincl = READ_ONCE(hdrincl);

	/*
	 *	Get and verify the address.
	 */
	memset(&fl6, 0, sizeof(fl6));

	fl6.flowi6_mark = sk->sk_mark;
	fl6.flowi6_uid = sk->sk_uid;

	ipcm6_init(&ipc6);
	ipc6.sockc.tsflags = sk->sk_tsflags;
	ipc6.sockc.mark = sk->sk_mark;

	if (sin6) {
		if (addr_len < SIN6_LEN_RFC2133)
			return -EINVAL;

		if (sin6->sin6_family && sin6->sin6_family != AF_INET6)
			return -EAFNOSUPPORT;

		/* port is the proto value [0..255] carried in nexthdr */
		proto = ntohs(sin6->sin6_port);

		if (!proto)
			proto = inet->inet_num;
		else if (proto != inet->inet_num)
			return -EINVAL;

		if (proto > 255)
			return -EINVAL;

		daddr = &sin6->sin6_addr;
		if (np->sndflow) {
			fl6.flowlabel = sin6->sin6_flowinfo&IPV6_FLOWINFO_MASK;
			if (fl6.flowlabel&IPV6_FLOWLABEL_MASK) {
				flowlabel = fl6_sock_lookup(sk, fl6.flowlabel);
				if (IS_ERR(flowlabel))
					return -EINVAL;
			}
		}

		/*
		 * Otherwise it will be difficult to maintain
		 * sk->sk_dst_cache.
		 */
		if (sk->sk_state == TCP_ESTABLISHED &&
		    ipv6_addr_equal(daddr, &sk->sk_v6_daddr))
			daddr = &sk->sk_v6_daddr;

		if (addr_len >= sizeof(struct sockaddr_in6) &&
		    sin6->sin6_scope_id &&
		    __ipv6_addr_needs_scope_id(__ipv6_addr_type(daddr)))
			fl6.flowi6_oif = sin6->sin6_scope_id;
	} else {
		if (sk->sk_state != TCP_ESTABLISHED)
			return -EDESTADDRREQ;

		proto = inet->inet_num;
		daddr = &sk->sk_v6_daddr;
		fl6.flowlabel = np->flow_label;
	}

	if (fl6.flowi6_oif == 0)
		fl6.flowi6_oif = sk->sk_bound_dev_if;

	if (msg->msg_controllen) {
		opt = &opt_space;
		memset(opt, 0, sizeof(struct ipv6_txoptions));
		opt->tot_len = sizeof(struct ipv6_txoptions);
		ipc6.opt = opt;

		err = ip6_datagram_send_ctl(sock_net(sk), sk, msg, &fl6, &ipc6);
		if (err < 0) {
			fl6_sock_release(flowlabel);
			return err;
		}
		if ((fl6.flowlabel&IPV6_FLOWLABEL_MASK) && !flowlabel) {
			flowlabel = fl6_sock_lookup(sk, fl6.flowlabel);
			if (IS_ERR(flowlabel))
				return -EINVAL;
		}
		if (!(opt->opt_nflen|opt->opt_flen))
			opt = NULL;
	}
	if (!opt) {
		opt = txopt_get(np);
		opt_to_free = opt;
	}
	if (flowlabel)
		opt = fl6_merge_options(&opt_space, flowlabel, opt);
	opt = ipv6_fixup_options(&opt_space, opt);

	fl6.flowi6_proto = proto;
	fl6.flowi6_mark = ipc6.sockc.mark;

	if (!hdrincl) {
		rfv.msg = msg;
		rfv.hlen = 0;
		err = rawv6_probe_proto_opt(&rfv, &fl6);
		if (err)
			goto out;
	}

	if (!ipv6_addr_any(daddr))
		fl6.daddr = *daddr;
	else
		fl6.daddr.s6_addr[15] = 0x1; /* :: means loopback (BSD'ism) */
	if (ipv6_addr_any(&fl6.saddr) && !ipv6_addr_any(&np->saddr))
		fl6.saddr = np->saddr;

	final_p = fl6_update_dst(&fl6, opt, &final);

	if (!fl6.flowi6_oif && ipv6_addr_is_multicast(&fl6.daddr))
		fl6.flowi6_oif = np->mcast_oif;
	else if (!fl6.flowi6_oif)
		fl6.flowi6_oif = np->ucast_oif;
	security_sk_classify_flow(sk, flowi6_to_flowi_common(&fl6));

	if (hdrincl)
		fl6.flowi6_flags |= FLOWI_FLAG_KNOWN_NH;

	if (ipc6.tclass < 0)
		ipc6.tclass = np->tclass;

	fl6.flowlabel = ip6_make_flowinfo(ipc6.tclass, fl6.flowlabel);

	dst = ip6_dst_lookup_flow(sock_net(sk), sk, &fl6, final_p);
	if (IS_ERR(dst)) {
		err = PTR_ERR(dst);
		goto out;
	}
	if (ipc6.hlimit < 0)
		ipc6.hlimit = ip6_sk_dst_hoplimit(np, &fl6, dst);

	if (ipc6.dontfrag < 0)
		ipc6.dontfrag = np->dontfrag;

	if (msg->msg_flags&MSG_CONFIRM)
		goto do_confirm;

back_from_confirm:
	if (hdrincl)
		err = rawv6_send_hdrinc(sk, msg, len, &fl6, &dst,
					msg->msg_flags, &ipc6.sockc);
	else {
		ipc6.opt = opt;
		lock_sock(sk);
		err = ip6_append_data(sk, raw6_getfrag, &rfv,
			len, 0, &ipc6, &fl6, (struct rt6_info *)dst,
			msg->msg_flags);

		if (err)
			ip6_flush_pending_frames(sk);
		else if (!(msg->msg_flags & MSG_MORE))
			err = rawv6_push_pending_frames(sk, &fl6, rp);
		release_sock(sk);
	}
done:
	dst_release(dst);
out:
	fl6_sock_release(flowlabel);
	txopt_put(opt_to_free);
	return err < 0 ? err : len;
do_confirm:
	if (msg->msg_flags & MSG_PROBE)
		dst_confirm_neigh(dst, &fl6.daddr);
	if (!(msg->msg_flags & MSG_PROBE) || len)
		goto back_from_confirm;
	err = 0;
	goto done;
}

static int rawv6_seticmpfilter(struct sock *sk, int level, int optname,
			       sockptr_t optval, int optlen)
{
	switch (optname) {
	case ICMPV6_FILTER:
		if (optlen > sizeof(struct icmp6_filter))
			optlen = sizeof(struct icmp6_filter);
		if (copy_from_sockptr(&raw6_sk(sk)->filter, optval, optlen))
			return -EFAULT;
		return 0;
	default:
		return -ENOPROTOOPT;
	}

	return 0;
}

static int rawv6_geticmpfilter(struct sock *sk, int level, int optname,
			       char __user *optval, int __user *optlen)
{
	int len;

	switch (optname) {
	case ICMPV6_FILTER:
		if (get_user(len, optlen))
			return -EFAULT;
		if (len < 0)
			return -EINVAL;
		if (len > sizeof(struct icmp6_filter))
			len = sizeof(struct icmp6_filter);
		if (put_user(len, optlen))
			return -EFAULT;
		if (copy_to_user(optval, &raw6_sk(sk)->filter, len))
			return -EFAULT;
		return 0;
	default:
		return -ENOPROTOOPT;
	}

	return 0;
}


static int do_rawv6_setsockopt(struct sock *sk, int level, int optname,
			       sockptr_t optval, unsigned int optlen)
{
	struct raw6_sock *rp = raw6_sk(sk);
	int val;

	if (copy_from_sockptr(&val, optval, sizeof(val)))
		return -EFAULT;

	switch (optname) {
	case IPV6_HDRINCL:
		if (sk->sk_type != SOCK_RAW)
			return -EINVAL;
		inet_sk(sk)->hdrincl = !!val;
		return 0;
	case IPV6_CHECKSUM:
		if (inet_sk(sk)->inet_num == IPPROTO_ICMPV6 &&
		    level == IPPROTO_IPV6) {
			/*
			 * RFC3542 tells that IPV6_CHECKSUM socket
			 * option in the IPPROTO_IPV6 level is not
			 * allowed on ICMPv6 sockets.
			 * If you want to set it, use IPPROTO_RAW
			 * level IPV6_CHECKSUM socket option
			 * (Linux extension).
			 */
			return -EINVAL;
		}

		/* You may get strange result with a positive odd offset;
		   RFC2292bis agrees with me. */
		if (val > 0 && (val&1))
			return -EINVAL;
		if (val < 0) {
			rp->checksum = 0;
		} else {
			rp->checksum = 1;
			rp->offset = val;
		}

		return 0;

	default:
		return -ENOPROTOOPT;
	}
}

static int rawv6_setsockopt(struct sock *sk, int level, int optname,
			    sockptr_t optval, unsigned int optlen)
{
	switch (level) {
	case SOL_RAW:
		break;

	case SOL_ICMPV6:
		if (inet_sk(sk)->inet_num != IPPROTO_ICMPV6)
			return -EOPNOTSUPP;
		return rawv6_seticmpfilter(sk, level, optname, optval, optlen);
	case SOL_IPV6:
		if (optname == IPV6_CHECKSUM ||
		    optname == IPV6_HDRINCL)
			break;
		fallthrough;
	default:
		return ipv6_setsockopt(sk, level, optname, optval, optlen);
	}

	return do_rawv6_setsockopt(sk, level, optname, optval, optlen);
}

static int do_rawv6_getsockopt(struct sock *sk, int level, int optname,
			    char __user *optval, int __user *optlen)
{
	struct raw6_sock *rp = raw6_sk(sk);
	int val, len;

	if (get_user(len, optlen))
		return -EFAULT;

	switch (optname) {
	case IPV6_HDRINCL:
		val = inet_sk(sk)->hdrincl;
		break;
	case IPV6_CHECKSUM:
		/*
		 * We allow getsockopt() for IPPROTO_IPV6-level
		 * IPV6_CHECKSUM socket option on ICMPv6 sockets
		 * since RFC3542 is silent about it.
		 */
		if (rp->checksum == 0)
			val = -1;
		else
			val = rp->offset;
		break;

	default:
		return -ENOPROTOOPT;
	}

	len = min_t(unsigned int, sizeof(int), len);

	if (put_user(len, optlen))
		return -EFAULT;
	if (copy_to_user(optval, &val, len))
		return -EFAULT;
	return 0;
}

static int rawv6_getsockopt(struct sock *sk, int level, int optname,
			  char __user *optval, int __user *optlen)
{
	switch (level) {
	case SOL_RAW:
		break;

	case SOL_ICMPV6:
		if (inet_sk(sk)->inet_num != IPPROTO_ICMPV6)
			return -EOPNOTSUPP;
		return rawv6_geticmpfilter(sk, level, optname, optval, optlen);
	case SOL_IPV6:
		if (optname == IPV6_CHECKSUM ||
		    optname == IPV6_HDRINCL)
			break;
		fallthrough;
	default:
		return ipv6_getsockopt(sk, level, optname, optval, optlen);
	}

	return do_rawv6_getsockopt(sk, level, optname, optval, optlen);
}

static int rawv6_ioctl(struct sock *sk, int cmd, unsigned long arg)
{
	switch (cmd) {
	case SIOCOUTQ: {
		int amount = sk_wmem_alloc_get(sk);

		return put_user(amount, (int __user *)arg);
	}
	case SIOCINQ: {
		struct sk_buff *skb;
		int amount = 0;

		spin_lock_bh(&sk->sk_receive_queue.lock);
		skb = skb_peek(&sk->sk_receive_queue);
		if (skb)
			amount = skb->len;
		spin_unlock_bh(&sk->sk_receive_queue.lock);
		return put_user(amount, (int __user *)arg);
	}

	default:
#ifdef CONFIG_IPV6_MROUTE
		return ip6mr_ioctl(sk, cmd, (void __user *)arg);
#else
		return -ENOIOCTLCMD;
#endif
	}
}

#ifdef CONFIG_COMPAT
static int compat_rawv6_ioctl(struct sock *sk, unsigned int cmd, unsigned long arg)
{
	switch (cmd) {
	case SIOCOUTQ:
	case SIOCINQ:
		return -ENOIOCTLCMD;
	default:
#ifdef CONFIG_IPV6_MROUTE
		return ip6mr_compat_ioctl(sk, cmd, compat_ptr(arg));
#else
		return -ENOIOCTLCMD;
#endif
	}
}
#endif

static void rawv6_close(struct sock *sk, long timeout)
{
	if (inet_sk(sk)->inet_num == IPPROTO_RAW)
		ip6_ra_control(sk, -1);
	ip6mr_sk_done(sk);
	sk_common_release(sk);
}

static void raw6_destroy(struct sock *sk)
{
	lock_sock(sk);
	ip6_flush_pending_frames(sk);
	release_sock(sk);

	inet6_destroy_sock(sk);
}

static int rawv6_init_sk(struct sock *sk)
{
	struct raw6_sock *rp = raw6_sk(sk);

	switch (inet_sk(sk)->inet_num) {
	case IPPROTO_ICMPV6:
		rp->checksum = 1;
		rp->offset   = 2;
		break;
	case IPPROTO_MH:
		rp->checksum = 1;
		rp->offset   = 4;
		break;
	default:
		break;
	}
	return 0;
}

struct proto rawv6_prot = {
	.name		   = "RAWv6",
	.owner		   = THIS_MODULE,
	.close		   = rawv6_close,
	.destroy	   = raw6_destroy,
	.connect	   = ip6_datagram_connect_v6_only,
	.disconnect	   = __udp_disconnect,
	.ioctl		   = rawv6_ioctl,
	.init		   = rawv6_init_sk,
	.setsockopt	   = rawv6_setsockopt,
	.getsockopt	   = rawv6_getsockopt,
	.sendmsg	   = rawv6_sendmsg,
	.recvmsg	   = rawv6_recvmsg,
	.bind		   = rawv6_bind,
	.backlog_rcv	   = rawv6_rcv_skb,
	.hash		   = raw_hash_sk,
	.unhash		   = raw_unhash_sk,
	.obj_size	   = sizeof(struct raw6_sock),
	.useroffset	   = offsetof(struct raw6_sock, filter),
	.usersize	   = sizeof_field(struct raw6_sock, filter),
	.h.raw_hash	   = &raw_v6_hashinfo,
#ifdef CONFIG_COMPAT
	.compat_ioctl	   = compat_rawv6_ioctl,
#endif
	.diag_destroy	   = raw_abort,
};

#ifdef CONFIG_PROC_FS
static int raw6_seq_show(struct seq_file *seq, void *v)
{
	if (v == SEQ_START_TOKEN) {
		seq_puts(seq, IPV6_SEQ_DGRAM_HEADER);
	} else {
		struct sock *sp = v;
		__u16 srcp  = inet_sk(sp)->inet_num;
		ip6_dgram_sock_seq_show(seq, v, srcp, 0,
					raw_seq_private(seq)->bucket);
	}
	return 0;
}

static const struct seq_operations raw6_seq_ops = {
	.start =	raw_seq_start,
	.next =		raw_seq_next,
	.stop =		raw_seq_stop,
	.show =		raw6_seq_show,
};

static int __net_init raw6_init_net(struct net *net)
{
	if (!proc_create_net_data("raw6", 0444, net->proc_net, &raw6_seq_ops,
			sizeof(struct raw_iter_state), &raw_v6_hashinfo))
		return -ENOMEM;

	return 0;
}

static void __net_exit raw6_exit_net(struct net *net)
{
	remove_proc_entry("raw6", net->proc_net);
}

static struct pernet_operations raw6_net_ops = {
	.init = raw6_init_net,
	.exit = raw6_exit_net,
};

int __init raw6_proc_init(void)
{
	return register_pernet_subsys(&raw6_net_ops);
}

void raw6_proc_exit(void)
{
	unregister_pernet_subsys(&raw6_net_ops);
}
#endif	/* CONFIG_PROC_FS */

/* Same as inet6_dgram_ops, sans udp_poll.  */
const struct proto_ops inet6_sockraw_ops = {
	.family		   = PF_INET6,
	.owner		   = THIS_MODULE,
	.release	   = inet6_release,
	.bind		   = inet6_bind,
	.connect	   = inet_dgram_connect,	/* ok		*/
	.socketpair	   = sock_no_socketpair,	/* a do nothing	*/
	.accept		   = sock_no_accept,		/* a do nothing	*/
	.getname	   = inet6_getname,
	.poll		   = datagram_poll,		/* ok		*/
	.ioctl		   = inet6_ioctl,		/* must change  */
	.gettstamp	   = sock_gettstamp,
	.listen		   = sock_no_listen,		/* ok		*/
	.shutdown	   = inet_shutdown,		/* ok		*/
	.setsockopt	   = sock_common_setsockopt,	/* ok		*/
	.getsockopt	   = sock_common_getsockopt,	/* ok		*/
	.sendmsg	   = inet_sendmsg,		/* ok		*/
	.recvmsg	   = sock_common_recvmsg,	/* ok		*/
	.mmap		   = sock_no_mmap,
	.sendpage	   = sock_no_sendpage,
#ifdef CONFIG_COMPAT
	.compat_ioctl	   = inet6_compat_ioctl,
#endif
};

static struct inet_protosw rawv6_protosw = {
	.type		= SOCK_RAW,
	.protocol	= IPPROTO_IP,	/* wild card */
	.prot		= &rawv6_prot,
	.ops		= &inet6_sockraw_ops,
	.flags		= INET_PROTOSW_REUSE,
};

int __init rawv6_init(void)
{
	return inet6_register_protosw(&rawv6_protosw);
}

void rawv6_exit(void)
{
	inet6_unregister_protosw(&rawv6_protosw);
}