root/net/ipv6/datagram.c
// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *      common UDP/RAW code
 *      Linux INET6 implementation
 *
 *      Authors:
 *      Pedro Roque             <roque@di.fc.ul.pt>
 */

#include <linux/capability.h>
#include <linux/errno.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/interrupt.h>
#include <linux/socket.h>
#include <linux/sockios.h>
#include <linux/in6.h>
#include <linux/ipv6.h>
#include <linux/route.h>
#include <linux/slab.h>
#include <linux/export.h>
#include <linux/icmp.h>

#include <net/ipv6.h>
#include <net/ndisc.h>
#include <net/addrconf.h>
#include <net/transp_v6.h>
#include <net/ip6_route.h>
#include <net/tcp_states.h>
#include <net/dsfield.h>
#include <net/sock_reuseport.h>

#include <linux/errqueue.h>
#include <linux/uaccess.h>

static bool ipv6_mapped_addr_any(const struct in6_addr *a)
{
        return ipv6_addr_v4mapped(a) && (a->s6_addr32[3] == 0);
}

static void ip6_datagram_flow_key_init(struct flowi6 *fl6,
                                       const struct sock *sk)
{
        const struct inet_sock *inet = inet_sk(sk);
        const struct ipv6_pinfo *np = inet6_sk(sk);
        int oif = sk->sk_bound_dev_if;

        memset(fl6, 0, sizeof(*fl6));
        fl6->flowi6_proto = sk->sk_protocol;
        fl6->daddr = sk->sk_v6_daddr;
        fl6->saddr = np->saddr;
        fl6->flowi6_mark = sk->sk_mark;
        fl6->fl6_dport = inet->inet_dport;
        fl6->fl6_sport = inet->inet_sport;
        fl6->flowlabel = ip6_make_flowinfo(np->tclass, np->flow_label);
        fl6->flowi6_uid = sk_uid(sk);

        if (!oif)
                oif = np->sticky_pktinfo.ipi6_ifindex;

        if (!oif) {
                if (ipv6_addr_is_multicast(&fl6->daddr))
                        oif = READ_ONCE(np->mcast_oif);
                else
                        oif = READ_ONCE(np->ucast_oif);
        }

        fl6->flowi6_oif = oif;
        security_sk_classify_flow(sk, flowi6_to_flowi_common(fl6));
}

int ip6_datagram_dst_update(struct sock *sk, bool fix_sk_saddr)
{
        struct ip6_flowlabel *flowlabel = NULL;
        struct inet_sock *inet = inet_sk(sk);
        struct ipv6_pinfo *np = inet6_sk(sk);
        struct ipv6_txoptions *opt;
        struct in6_addr *final_p;
        struct dst_entry *dst;
        struct flowi6 *fl6;
        int err = 0;

        if (inet6_test_bit(SNDFLOW, sk) &&
            (np->flow_label & IPV6_FLOWLABEL_MASK)) {
                flowlabel = fl6_sock_lookup(sk, np->flow_label);
                if (IS_ERR(flowlabel))
                        return -EINVAL;
        }
        fl6 = &inet_sk(sk)->cork.fl.u.ip6;
        ip6_datagram_flow_key_init(fl6, sk);

        rcu_read_lock();
        opt = flowlabel ? flowlabel->opt : rcu_dereference(np->opt);
        final_p = fl6_update_dst(fl6, opt, &np->final);
        rcu_read_unlock();

        dst = ip6_dst_lookup_flow(sock_net(sk), sk, fl6, final_p);
        if (IS_ERR(dst)) {
                err = PTR_ERR(dst);
                goto out;
        }

        if (fix_sk_saddr) {
                if (ipv6_addr_any(&np->saddr))
                        np->saddr = fl6->saddr;

                if (ipv6_addr_any(&sk->sk_v6_rcv_saddr)) {
                        sk->sk_v6_rcv_saddr = fl6->saddr;
                        inet->inet_rcv_saddr = LOOPBACK4_IPV6;
                        if (sk->sk_prot->rehash)
                                sk->sk_prot->rehash(sk);
                }
        }

        ip6_sk_dst_store_flow(sk, dst, fl6);

out:
        fl6_sock_release(flowlabel);
        return err;
}

void ip6_datagram_release_cb(struct sock *sk)
{
        struct dst_entry *dst;

        if (ipv6_addr_v4mapped(&sk->sk_v6_daddr))
                return;

        rcu_read_lock();
        dst = __sk_dst_get(sk);
        if (!dst || !READ_ONCE(dst->obsolete) ||
            dst->ops->check(dst, inet6_sk(sk)->dst_cookie)) {
                rcu_read_unlock();
                return;
        }
        rcu_read_unlock();

        ip6_datagram_dst_update(sk, false);
}
EXPORT_SYMBOL_GPL(ip6_datagram_release_cb);

int __ip6_datagram_connect(struct sock *sk, struct sockaddr_unsized *uaddr,
                           int addr_len)
{
        struct sockaddr_in6     *usin = (struct sockaddr_in6 *) uaddr;
        struct inet_sock        *inet = inet_sk(sk);
        struct ipv6_pinfo       *np = inet6_sk(sk);
        struct in6_addr         *daddr, old_daddr;
        __be32                  fl6_flowlabel = 0;
        __be32                  old_fl6_flowlabel;
        __be16                  old_dport;
        int                     addr_type;
        int                     err;

        if (usin->sin6_family == AF_INET) {
                if (ipv6_only_sock(sk))
                        return -EAFNOSUPPORT;
                err = __ip4_datagram_connect(sk, uaddr, addr_len);
                goto ipv4_connected;
        }

        if (addr_len < SIN6_LEN_RFC2133)
                return -EINVAL;

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

        if (inet6_test_bit(SNDFLOW, sk))
                fl6_flowlabel = usin->sin6_flowinfo & IPV6_FLOWINFO_MASK;

        if (ipv6_addr_any(&usin->sin6_addr)) {
                /*
                 *      connect to self
                 */
                if (ipv6_addr_v4mapped(&sk->sk_v6_rcv_saddr))
                        ipv6_addr_set_v4mapped(htonl(INADDR_LOOPBACK),
                                               &usin->sin6_addr);
                else
                        usin->sin6_addr = in6addr_loopback;
        }

        addr_type = ipv6_addr_type(&usin->sin6_addr);

        daddr = &usin->sin6_addr;

        if (addr_type & IPV6_ADDR_MAPPED) {
                struct sockaddr_in sin;

                if (ipv6_only_sock(sk)) {
                        err = -ENETUNREACH;
                        goto out;
                }
                sin.sin_family = AF_INET;
                sin.sin_addr.s_addr = daddr->s6_addr32[3];
                sin.sin_port = usin->sin6_port;

                err = __ip4_datagram_connect(sk,
                                             (struct sockaddr_unsized *)&sin,
                                             sizeof(sin));

ipv4_connected:
                if (err)
                        goto out;

                ipv6_addr_set_v4mapped(inet->inet_daddr, &sk->sk_v6_daddr);

                if (ipv6_addr_any(&np->saddr) ||
                    ipv6_mapped_addr_any(&np->saddr))
                        ipv6_addr_set_v4mapped(inet->inet_saddr, &np->saddr);

                if (ipv6_addr_any(&sk->sk_v6_rcv_saddr) ||
                    ipv6_mapped_addr_any(&sk->sk_v6_rcv_saddr)) {
                        ipv6_addr_set_v4mapped(inet->inet_rcv_saddr,
                                               &sk->sk_v6_rcv_saddr);
                        if (sk->sk_prot->rehash)
                                sk->sk_prot->rehash(sk);
                }

                goto out;
        }

        if (__ipv6_addr_needs_scope_id(addr_type)) {
                if (addr_len >= sizeof(struct sockaddr_in6) &&
                    usin->sin6_scope_id) {
                        if (!sk_dev_equal_l3scope(sk, usin->sin6_scope_id)) {
                                err = -EINVAL;
                                goto out;
                        }
                        WRITE_ONCE(sk->sk_bound_dev_if, usin->sin6_scope_id);
                }

                if (!sk->sk_bound_dev_if && (addr_type & IPV6_ADDR_MULTICAST))
                        WRITE_ONCE(sk->sk_bound_dev_if, READ_ONCE(np->mcast_oif));

                /* Connect to link-local address requires an interface */
                if (!sk->sk_bound_dev_if) {
                        err = -EINVAL;
                        goto out;
                }
        }

        /* save the current peer information before updating it */
        old_daddr = sk->sk_v6_daddr;
        old_fl6_flowlabel = np->flow_label;
        old_dport = inet->inet_dport;

        sk->sk_v6_daddr = *daddr;
        np->flow_label = fl6_flowlabel;
        inet->inet_dport = usin->sin6_port;

        /*
         *      Check for a route to destination an obtain the
         *      destination cache for it.
         */

        err = ip6_datagram_dst_update(sk, true);
        if (err) {
                /* Restore the socket peer info, to keep it consistent with
                 * the old socket state
                 */
                sk->sk_v6_daddr = old_daddr;
                np->flow_label = old_fl6_flowlabel;
                inet->inet_dport = old_dport;
                goto out;
        }

        reuseport_has_conns_set(sk);
        sk->sk_state = TCP_ESTABLISHED;
        sk_set_txhash(sk);
out:
        return err;
}
EXPORT_SYMBOL_GPL(__ip6_datagram_connect);

int ip6_datagram_connect(struct sock *sk, struct sockaddr_unsized *uaddr, int addr_len)
{
        int res;

        lock_sock(sk);
        res = __ip6_datagram_connect(sk, uaddr, addr_len);
        release_sock(sk);
        return res;
}
EXPORT_SYMBOL_GPL(ip6_datagram_connect);

int ip6_datagram_connect_v6_only(struct sock *sk, struct sockaddr_unsized *uaddr,
                                 int addr_len)
{
        DECLARE_SOCKADDR(struct sockaddr_in6 *, sin6, uaddr);
        if (sin6->sin6_family != AF_INET6)
                return -EAFNOSUPPORT;
        return ip6_datagram_connect(sk, uaddr, addr_len);
}
EXPORT_SYMBOL_GPL(ip6_datagram_connect_v6_only);

static void ipv6_icmp_error_rfc4884(const struct sk_buff *skb,
                                    struct sock_ee_data_rfc4884 *out)
{
        switch (icmp6_hdr(skb)->icmp6_type) {
        case ICMPV6_TIME_EXCEED:
        case ICMPV6_DEST_UNREACH:
                ip_icmp_error_rfc4884(skb, out, sizeof(struct icmp6hdr),
                                      icmp6_hdr(skb)->icmp6_datagram_len * 8);
        }
}

void ipv6_icmp_error(struct sock *sk, struct sk_buff *skb, int err,
                     __be16 port, u32 info, u8 *payload)
{
        struct icmp6hdr *icmph = icmp6_hdr(skb);
        struct sock_exterr_skb *serr;

        if (!inet6_test_bit(RECVERR6, sk))
                return;

        skb = skb_clone(skb, GFP_ATOMIC);
        if (!skb)
                return;

        skb->protocol = htons(ETH_P_IPV6);

        serr = SKB_EXT_ERR(skb);
        serr->ee.ee_errno = err;
        serr->ee.ee_origin = SO_EE_ORIGIN_ICMP6;
        serr->ee.ee_type = icmph->icmp6_type;
        serr->ee.ee_code = icmph->icmp6_code;
        serr->ee.ee_pad = 0;
        serr->ee.ee_info = info;
        serr->ee.ee_data = 0;
        serr->addr_offset = (u8 *)&(((struct ipv6hdr *)(icmph + 1))->daddr) -
                                  skb_network_header(skb);
        serr->port = port;

        __skb_pull(skb, payload - skb->data);

        if (inet6_test_bit(RECVERR6_RFC4884, sk))
                ipv6_icmp_error_rfc4884(skb, &serr->ee.ee_rfc4884);

        skb_reset_transport_header(skb);

        if (sock_queue_err_skb(sk, skb))
                kfree_skb(skb);
}
EXPORT_SYMBOL_GPL(ipv6_icmp_error);

void ipv6_local_error(struct sock *sk, int err, struct flowi6 *fl6, u32 info)
{
        struct sock_exterr_skb *serr;
        struct ipv6hdr *iph;
        struct sk_buff *skb;

        if (!inet6_test_bit(RECVERR6, sk))
                return;

        skb = alloc_skb(sizeof(struct ipv6hdr), GFP_ATOMIC);
        if (!skb)
                return;

        skb->protocol = htons(ETH_P_IPV6);

        skb_put(skb, sizeof(struct ipv6hdr));
        skb_reset_network_header(skb);
        iph = ipv6_hdr(skb);
        iph->daddr = fl6->daddr;
        ip6_flow_hdr(iph, 0, 0);

        serr = SKB_EXT_ERR(skb);
        serr->ee.ee_errno = err;
        serr->ee.ee_origin = SO_EE_ORIGIN_LOCAL;
        serr->ee.ee_type = 0;
        serr->ee.ee_code = 0;
        serr->ee.ee_pad = 0;
        serr->ee.ee_info = info;
        serr->ee.ee_data = 0;
        serr->addr_offset = (u8 *)&iph->daddr - skb_network_header(skb);
        serr->port = fl6->fl6_dport;

        __skb_pull(skb, skb_tail_pointer(skb) - skb->data);
        skb_reset_transport_header(skb);

        if (sock_queue_err_skb(sk, skb))
                kfree_skb(skb);
}

void ipv6_local_rxpmtu(struct sock *sk, struct flowi6 *fl6, u32 mtu)
{
        struct ipv6_pinfo *np = inet6_sk(sk);
        struct ipv6hdr *iph;
        struct sk_buff *skb;
        struct ip6_mtuinfo *mtu_info;

        if (!np->rxopt.bits.rxpmtu)
                return;

        skb = alloc_skb(sizeof(struct ipv6hdr), GFP_ATOMIC);
        if (!skb)
                return;

        skb_put(skb, sizeof(struct ipv6hdr));
        skb_reset_network_header(skb);
        iph = ipv6_hdr(skb);
        iph->daddr = fl6->daddr;

        mtu_info = IP6CBMTU(skb);

        mtu_info->ip6m_mtu = mtu;
        mtu_info->ip6m_addr.sin6_family = AF_INET6;
        mtu_info->ip6m_addr.sin6_port = 0;
        mtu_info->ip6m_addr.sin6_flowinfo = 0;
        mtu_info->ip6m_addr.sin6_scope_id = fl6->flowi6_oif;
        mtu_info->ip6m_addr.sin6_addr = ipv6_hdr(skb)->daddr;

        __skb_pull(skb, skb_tail_pointer(skb) - skb->data);
        skb_reset_transport_header(skb);

        skb = xchg(&np->rxpmtu, skb);
        kfree_skb(skb);
}

/* For some errors we have valid addr_offset even with zero payload and
 * zero port. Also, addr_offset should be supported if port is set.
 */
static inline bool ipv6_datagram_support_addr(struct sock_exterr_skb *serr)
{
        return serr->ee.ee_origin == SO_EE_ORIGIN_ICMP6 ||
               serr->ee.ee_origin == SO_EE_ORIGIN_ICMP ||
               serr->ee.ee_origin == SO_EE_ORIGIN_LOCAL || serr->port;
}

/* IPv6 supports cmsg on all origins aside from SO_EE_ORIGIN_LOCAL.
 *
 * At one point, excluding local errors was a quick test to identify icmp/icmp6
 * errors. This is no longer true, but the test remained, so the v6 stack,
 * unlike v4, also honors cmsg requests on all wifi and timestamp errors.
 */
static bool ip6_datagram_support_cmsg(struct sk_buff *skb,
                                      struct sock_exterr_skb *serr)
{
        if (serr->ee.ee_origin == SO_EE_ORIGIN_ICMP ||
            serr->ee.ee_origin == SO_EE_ORIGIN_ICMP6)
                return true;

        if (serr->ee.ee_origin == SO_EE_ORIGIN_LOCAL)
                return false;

        if (!IP6CB(skb)->iif)
                return false;

        return true;
}

/*
 *      Handle MSG_ERRQUEUE
 */
int ipv6_recv_error(struct sock *sk, struct msghdr *msg, int len, int *addr_len)
{
        struct ipv6_pinfo *np = inet6_sk(sk);
        struct sock_exterr_skb *serr;
        struct sk_buff *skb;
        DECLARE_SOCKADDR(struct sockaddr_in6 *, sin, msg->msg_name);
        struct {
                struct sock_extended_err ee;
                struct sockaddr_in6      offender;
        } errhdr;
        int err;
        int copied;

        err = -EAGAIN;
        skb = sock_dequeue_err_skb(sk);
        if (!skb)
                goto out;

        copied = skb->len;
        if (copied > len) {
                msg->msg_flags |= MSG_TRUNC;
                copied = len;
        }
        err = skb_copy_datagram_msg(skb, 0, msg, copied);
        if (unlikely(err)) {
                kfree_skb(skb);
                return err;
        }
        sock_recv_timestamp(msg, sk, skb);

        serr = SKB_EXT_ERR(skb);

        if (sin && ipv6_datagram_support_addr(serr)) {
                const unsigned char *nh = skb_network_header(skb);
                sin->sin6_family = AF_INET6;
                sin->sin6_flowinfo = 0;
                sin->sin6_port = serr->port;
                if (skb->protocol == htons(ETH_P_IPV6)) {
                        const struct ipv6hdr *ip6h = container_of((struct in6_addr *)(nh + serr->addr_offset),
                                                                  struct ipv6hdr, daddr);
                        sin->sin6_addr = ip6h->daddr;
                        if (inet6_test_bit(SNDFLOW, sk))
                                sin->sin6_flowinfo = ip6_flowinfo(ip6h);
                        sin->sin6_scope_id =
                                ipv6_iface_scope_id(&sin->sin6_addr,
                                                    IP6CB(skb)->iif);
                } else {
                        ipv6_addr_set_v4mapped(*(__be32 *)(nh + serr->addr_offset),
                                               &sin->sin6_addr);
                        sin->sin6_scope_id = 0;
                }
                *addr_len = sizeof(*sin);
        }

        memcpy(&errhdr.ee, &serr->ee, sizeof(struct sock_extended_err));
        sin = &errhdr.offender;
        memset(sin, 0, sizeof(*sin));

        if (ip6_datagram_support_cmsg(skb, serr)) {
                sin->sin6_family = AF_INET6;
                if (np->rxopt.all)
                        ip6_datagram_recv_common_ctl(sk, msg, skb);
                if (skb->protocol == htons(ETH_P_IPV6)) {
                        sin->sin6_addr = ipv6_hdr(skb)->saddr;
                        if (np->rxopt.all)
                                ip6_datagram_recv_specific_ctl(sk, msg, skb);
                        sin->sin6_scope_id =
                                ipv6_iface_scope_id(&sin->sin6_addr,
                                                    IP6CB(skb)->iif);
                } else {
                        ipv6_addr_set_v4mapped(ip_hdr(skb)->saddr,
                                               &sin->sin6_addr);
                        if (inet_cmsg_flags(inet_sk(sk)))
                                ip_cmsg_recv(msg, skb);
                }
        }

        put_cmsg(msg, SOL_IPV6, IPV6_RECVERR, sizeof(errhdr), &errhdr);

        /* Now we could try to dump offended packet options */

        msg->msg_flags |= MSG_ERRQUEUE;
        err = copied;

        consume_skb(skb);
out:
        return err;
}
EXPORT_SYMBOL_GPL(ipv6_recv_error);

/*
 *      Handle IPV6_RECVPATHMTU
 */
int ipv6_recv_rxpmtu(struct sock *sk, struct msghdr *msg, int len,
                     int *addr_len)
{
        struct ipv6_pinfo *np = inet6_sk(sk);
        struct sk_buff *skb;
        struct ip6_mtuinfo mtu_info;
        DECLARE_SOCKADDR(struct sockaddr_in6 *, sin, msg->msg_name);
        int err;
        int copied;

        err = -EAGAIN;
        skb = xchg(&np->rxpmtu, NULL);
        if (!skb)
                goto out;

        copied = skb->len;
        if (copied > len) {
                msg->msg_flags |= MSG_TRUNC;
                copied = len;
        }
        err = skb_copy_datagram_msg(skb, 0, msg, copied);
        if (err)
                goto out_free_skb;

        sock_recv_timestamp(msg, sk, skb);

        memcpy(&mtu_info, IP6CBMTU(skb), sizeof(mtu_info));

        if (sin) {
                sin->sin6_family = AF_INET6;
                sin->sin6_flowinfo = 0;
                sin->sin6_port = 0;
                sin->sin6_scope_id = mtu_info.ip6m_addr.sin6_scope_id;
                sin->sin6_addr = mtu_info.ip6m_addr.sin6_addr;
                *addr_len = sizeof(*sin);
        }

        put_cmsg(msg, SOL_IPV6, IPV6_PATHMTU, sizeof(mtu_info), &mtu_info);

        err = copied;

out_free_skb:
        kfree_skb(skb);
out:
        return err;
}


void ip6_datagram_recv_common_ctl(struct sock *sk, struct msghdr *msg,
                                 struct sk_buff *skb)
{
        struct ipv6_pinfo *np = inet6_sk(sk);
        bool is_ipv6 = skb->protocol == htons(ETH_P_IPV6);

        if (np->rxopt.bits.rxinfo) {
                struct in6_pktinfo src_info;

                if (is_ipv6) {
                        src_info.ipi6_ifindex = IP6CB(skb)->iif;
                        src_info.ipi6_addr = ipv6_hdr(skb)->daddr;
                } else {
                        src_info.ipi6_ifindex =
                                PKTINFO_SKB_CB(skb)->ipi_ifindex;
                        ipv6_addr_set_v4mapped(ip_hdr(skb)->daddr,
                                               &src_info.ipi6_addr);
                }

                if (src_info.ipi6_ifindex >= 0)
                        put_cmsg(msg, SOL_IPV6, IPV6_PKTINFO,
                                 sizeof(src_info), &src_info);
        }
}

void ip6_datagram_recv_specific_ctl(struct sock *sk, struct msghdr *msg,
                                    struct sk_buff *skb)
{
        struct ipv6_pinfo *np = inet6_sk(sk);
        struct inet6_skb_parm *opt = IP6CB(skb);
        unsigned char *nh = skb_network_header(skb);

        if (np->rxopt.bits.rxhlim) {
                int hlim = ipv6_hdr(skb)->hop_limit;
                put_cmsg(msg, SOL_IPV6, IPV6_HOPLIMIT, sizeof(hlim), &hlim);
        }

        if (np->rxopt.bits.rxtclass) {
                int tclass = ipv6_get_dsfield(ipv6_hdr(skb));
                put_cmsg(msg, SOL_IPV6, IPV6_TCLASS, sizeof(tclass), &tclass);
        }

        if (np->rxopt.bits.rxflow) {
                __be32 flowinfo = ip6_flowinfo((struct ipv6hdr *)nh);
                if (flowinfo)
                        put_cmsg(msg, SOL_IPV6, IPV6_FLOWINFO, sizeof(flowinfo), &flowinfo);
        }

        /* HbH is allowed only once */
        if (np->rxopt.bits.hopopts && (opt->flags & IP6SKB_HOPBYHOP)) {
                u8 *ptr = nh + sizeof(struct ipv6hdr);
                put_cmsg(msg, SOL_IPV6, IPV6_HOPOPTS, (ptr[1]+1)<<3, ptr);
        }

        if (opt->lastopt &&
            (np->rxopt.bits.dstopts || np->rxopt.bits.srcrt)) {
                /*
                 * Silly enough, but we need to reparse in order to
                 * report extension headers (except for HbH)
                 * in order.
                 *
                 * Also note that IPV6_RECVRTHDRDSTOPTS is NOT
                 * (and WILL NOT be) defined because
                 * IPV6_RECVDSTOPTS is more generic. --yoshfuji
                 */
                unsigned int off = sizeof(struct ipv6hdr);
                u8 nexthdr = ipv6_hdr(skb)->nexthdr;

                while (off <= opt->lastopt) {
                        unsigned int len;
                        u8 *ptr = nh + off;

                        switch (nexthdr) {
                        case IPPROTO_DSTOPTS:
                                nexthdr = ptr[0];
                                len = (ptr[1] + 1) << 3;
                                if (np->rxopt.bits.dstopts)
                                        put_cmsg(msg, SOL_IPV6, IPV6_DSTOPTS, len, ptr);
                                break;
                        case IPPROTO_ROUTING:
                                nexthdr = ptr[0];
                                len = (ptr[1] + 1) << 3;
                                if (np->rxopt.bits.srcrt)
                                        put_cmsg(msg, SOL_IPV6, IPV6_RTHDR, len, ptr);
                                break;
                        case IPPROTO_AH:
                                nexthdr = ptr[0];
                                len = (ptr[1] + 2) << 2;
                                break;
                        default:
                                nexthdr = ptr[0];
                                len = (ptr[1] + 1) << 3;
                                break;
                        }

                        off += len;
                }
        }

        /* socket options in old style */
        if (np->rxopt.bits.rxoinfo) {
                struct in6_pktinfo src_info;

                src_info.ipi6_ifindex = opt->iif;
                src_info.ipi6_addr = ipv6_hdr(skb)->daddr;
                put_cmsg(msg, SOL_IPV6, IPV6_2292PKTINFO, sizeof(src_info), &src_info);
        }
        if (np->rxopt.bits.rxohlim) {
                int hlim = ipv6_hdr(skb)->hop_limit;
                put_cmsg(msg, SOL_IPV6, IPV6_2292HOPLIMIT, sizeof(hlim), &hlim);
        }
        if (np->rxopt.bits.ohopopts && (opt->flags & IP6SKB_HOPBYHOP)) {
                u8 *ptr = nh + sizeof(struct ipv6hdr);
                put_cmsg(msg, SOL_IPV6, IPV6_2292HOPOPTS, (ptr[1]+1)<<3, ptr);
        }
        if (np->rxopt.bits.odstopts && opt->dst0) {
                u8 *ptr = nh + opt->dst0;
                put_cmsg(msg, SOL_IPV6, IPV6_2292DSTOPTS, (ptr[1]+1)<<3, ptr);
        }
        if (np->rxopt.bits.osrcrt && opt->srcrt) {
                struct ipv6_rt_hdr *rthdr = (struct ipv6_rt_hdr *)(nh + opt->srcrt);
                put_cmsg(msg, SOL_IPV6, IPV6_2292RTHDR, (rthdr->hdrlen+1) << 3, rthdr);
        }
        if (np->rxopt.bits.odstopts && opt->dst1) {
                u8 *ptr = nh + opt->dst1;
                put_cmsg(msg, SOL_IPV6, IPV6_2292DSTOPTS, (ptr[1]+1)<<3, ptr);
        }
        if (np->rxopt.bits.rxorigdstaddr) {
                struct sockaddr_in6 sin6;
                __be16 _ports[2], *ports;

                ports = skb_header_pointer(skb, skb_transport_offset(skb),
                                           sizeof(_ports), &_ports);
                if (ports) {
                        /* All current transport protocols have the port numbers in the
                         * first four bytes of the transport header and this function is
                         * written with this assumption in mind.
                         */
                        sin6.sin6_family = AF_INET6;
                        sin6.sin6_addr = ipv6_hdr(skb)->daddr;
                        sin6.sin6_port = ports[1];
                        sin6.sin6_flowinfo = 0;
                        sin6.sin6_scope_id =
                                ipv6_iface_scope_id(&ipv6_hdr(skb)->daddr,
                                                    opt->iif);

                        put_cmsg(msg, SOL_IPV6, IPV6_ORIGDSTADDR, sizeof(sin6), &sin6);
                }
        }
        if (np->rxopt.bits.recvfragsize && opt->frag_max_size) {
                int val = opt->frag_max_size;

                put_cmsg(msg, SOL_IPV6, IPV6_RECVFRAGSIZE, sizeof(val), &val);
        }
}

void ip6_datagram_recv_ctl(struct sock *sk, struct msghdr *msg,
                          struct sk_buff *skb)
{
        ip6_datagram_recv_common_ctl(sk, msg, skb);
        ip6_datagram_recv_specific_ctl(sk, msg, skb);
}
EXPORT_SYMBOL_GPL(ip6_datagram_recv_ctl);

int ip6_datagram_send_ctl(struct net *net, struct sock *sk,
                          struct msghdr *msg, struct flowi6 *fl6,
                          struct ipcm6_cookie *ipc6)
{
        struct in6_pktinfo *src_info;
        struct cmsghdr *cmsg;
        struct ipv6_rt_hdr *orthdr;
        struct ipv6_rt_hdr *rthdr;
        struct ipv6_opt_hdr *hdr;
        struct ipv6_txoptions *opt = ipc6->opt;
        int len;
        int err = 0;

        for_each_cmsghdr(cmsg, msg) {
                int addr_type;

                if (!CMSG_OK(msg, cmsg)) {
                        err = -EINVAL;
                        goto exit_f;
                }

                if (cmsg->cmsg_level == SOL_SOCKET) {
                        err = __sock_cmsg_send(sk, cmsg, &ipc6->sockc);
                        if (err)
                                return err;
                        continue;
                }

                if (cmsg->cmsg_level != SOL_IPV6)
                        continue;

                switch (cmsg->cmsg_type) {
                case IPV6_PKTINFO:
                case IPV6_2292PKTINFO:
                    {
                        struct net_device *dev = NULL;
                        int src_idx;

                        if (cmsg->cmsg_len < CMSG_LEN(sizeof(struct in6_pktinfo))) {
                                err = -EINVAL;
                                goto exit_f;
                        }

                        src_info = (struct in6_pktinfo *)CMSG_DATA(cmsg);
                        src_idx = src_info->ipi6_ifindex;

                        if (src_idx) {
                                if (fl6->flowi6_oif &&
                                    src_idx != fl6->flowi6_oif &&
                                    (READ_ONCE(sk->sk_bound_dev_if) != fl6->flowi6_oif ||
                                     !sk_dev_equal_l3scope(sk, src_idx)))
                                        return -EINVAL;
                                fl6->flowi6_oif = src_idx;
                        }

                        addr_type = __ipv6_addr_type(&src_info->ipi6_addr);

                        rcu_read_lock();
                        if (fl6->flowi6_oif) {
                                dev = dev_get_by_index_rcu(net, fl6->flowi6_oif);
                                if (!dev) {
                                        rcu_read_unlock();
                                        return -ENODEV;
                                }
                        } else if (addr_type & IPV6_ADDR_LINKLOCAL) {
                                rcu_read_unlock();
                                return -EINVAL;
                        }

                        if (addr_type != IPV6_ADDR_ANY) {
                                int strict = __ipv6_addr_src_scope(addr_type) <= IPV6_ADDR_SCOPE_LINKLOCAL;
                                if (!ipv6_can_nonlocal_bind(net, inet_sk(sk)) &&
                                    !ipv6_chk_addr_and_flags(net, &src_info->ipi6_addr,
                                                             dev, !strict, 0,
                                                             IFA_F_TENTATIVE) &&
                                    !ipv6_chk_acast_addr_src(net, dev,
                                                             &src_info->ipi6_addr))
                                        err = -EINVAL;
                                else
                                        fl6->saddr = src_info->ipi6_addr;
                        }

                        rcu_read_unlock();

                        if (err)
                                goto exit_f;

                        break;
                    }

                case IPV6_FLOWINFO:
                        if (cmsg->cmsg_len < CMSG_LEN(4)) {
                                err = -EINVAL;
                                goto exit_f;
                        }

                        if (fl6->flowlabel&IPV6_FLOWINFO_MASK) {
                                if ((fl6->flowlabel^*(__be32 *)CMSG_DATA(cmsg))&~IPV6_FLOWINFO_MASK) {
                                        err = -EINVAL;
                                        goto exit_f;
                                }
                        }
                        fl6->flowlabel = IPV6_FLOWINFO_MASK & *(__be32 *)CMSG_DATA(cmsg);
                        break;

                case IPV6_2292HOPOPTS:
                case IPV6_HOPOPTS:
                        if (opt->hopopt || cmsg->cmsg_len < CMSG_LEN(sizeof(struct ipv6_opt_hdr))) {
                                err = -EINVAL;
                                goto exit_f;
                        }

                        hdr = (struct ipv6_opt_hdr *)CMSG_DATA(cmsg);
                        len = ((hdr->hdrlen + 1) << 3);
                        if (cmsg->cmsg_len < CMSG_LEN(len)) {
                                err = -EINVAL;
                                goto exit_f;
                        }
                        if (!ns_capable(net->user_ns, CAP_NET_RAW)) {
                                err = -EPERM;
                                goto exit_f;
                        }
                        opt->opt_nflen += len;
                        opt->hopopt = hdr;
                        break;

                case IPV6_2292DSTOPTS:
                        if (cmsg->cmsg_len < CMSG_LEN(sizeof(struct ipv6_opt_hdr))) {
                                err = -EINVAL;
                                goto exit_f;
                        }

                        hdr = (struct ipv6_opt_hdr *)CMSG_DATA(cmsg);
                        len = ((hdr->hdrlen + 1) << 3);
                        if (cmsg->cmsg_len < CMSG_LEN(len)) {
                                err = -EINVAL;
                                goto exit_f;
                        }
                        if (!ns_capable(net->user_ns, CAP_NET_RAW)) {
                                err = -EPERM;
                                goto exit_f;
                        }
                        if (opt->dst1opt) {
                                err = -EINVAL;
                                goto exit_f;
                        }
                        opt->opt_flen += len;
                        opt->dst1opt = hdr;
                        break;

                case IPV6_DSTOPTS:
                case IPV6_RTHDRDSTOPTS:
                        if (cmsg->cmsg_len < CMSG_LEN(sizeof(struct ipv6_opt_hdr))) {
                                err = -EINVAL;
                                goto exit_f;
                        }

                        hdr = (struct ipv6_opt_hdr *)CMSG_DATA(cmsg);
                        len = ((hdr->hdrlen + 1) << 3);
                        if (cmsg->cmsg_len < CMSG_LEN(len)) {
                                err = -EINVAL;
                                goto exit_f;
                        }
                        if (!ns_capable(net->user_ns, CAP_NET_RAW)) {
                                err = -EPERM;
                                goto exit_f;
                        }
                        if (cmsg->cmsg_type == IPV6_DSTOPTS) {
                                if (opt->dst1opt)
                                        opt->opt_flen -= ipv6_optlen(opt->dst1opt);
                                opt->opt_flen += len;
                                opt->dst1opt = hdr;
                        } else {
                                if (opt->dst0opt)
                                        opt->opt_nflen -= ipv6_optlen(opt->dst0opt);
                                opt->opt_nflen += len;
                                opt->dst0opt = hdr;
                        }
                        break;

                case IPV6_2292RTHDR:
                case IPV6_RTHDR:
                        if (cmsg->cmsg_len < CMSG_LEN(sizeof(struct ipv6_rt_hdr))) {
                                err = -EINVAL;
                                goto exit_f;
                        }

                        rthdr = (struct ipv6_rt_hdr *)CMSG_DATA(cmsg);

                        switch (rthdr->type) {
#if IS_ENABLED(CONFIG_IPV6_MIP6)
                        case IPV6_SRCRT_TYPE_2:
                                if (rthdr->hdrlen != 2 ||
                                    rthdr->segments_left != 1) {
                                        err = -EINVAL;
                                        goto exit_f;
                                }
                                break;
#endif
                        default:
                                err = -EINVAL;
                                goto exit_f;
                        }

                        len = ((rthdr->hdrlen + 1) << 3);

                        if (cmsg->cmsg_len < CMSG_LEN(len)) {
                                err = -EINVAL;
                                goto exit_f;
                        }

                        /* segments left must also match */
                        if ((rthdr->hdrlen >> 1) != rthdr->segments_left) {
                                err = -EINVAL;
                                goto exit_f;
                        }

                        orthdr = opt->srcrt;
                        if (orthdr)
                                opt->opt_nflen -= ((orthdr->hdrlen + 1) << 3);
                        opt->opt_nflen += len;
                        opt->srcrt = rthdr;

                        if (cmsg->cmsg_type == IPV6_2292RTHDR && opt->dst1opt) {
                                int dsthdrlen = ((opt->dst1opt->hdrlen+1)<<3);

                                if (opt->dst0opt)
                                        opt->opt_nflen -= ipv6_optlen(opt->dst0opt);
                                opt->opt_nflen += dsthdrlen;
                                opt->dst0opt = opt->dst1opt;
                                opt->dst1opt = NULL;
                                opt->opt_flen -= dsthdrlen;
                        }

                        break;

                case IPV6_2292HOPLIMIT:
                case IPV6_HOPLIMIT:
                        if (cmsg->cmsg_len != CMSG_LEN(sizeof(int))) {
                                err = -EINVAL;
                                goto exit_f;
                        }

                        ipc6->hlimit = *(int *)CMSG_DATA(cmsg);
                        if (ipc6->hlimit < -1 || ipc6->hlimit > 0xff) {
                                err = -EINVAL;
                                goto exit_f;
                        }

                        break;

                case IPV6_TCLASS:
                    {
                        int tc;

                        err = -EINVAL;
                        if (cmsg->cmsg_len != CMSG_LEN(sizeof(int)))
                                goto exit_f;

                        tc = *(int *)CMSG_DATA(cmsg);
                        if (tc < -1 || tc > 0xff)
                                goto exit_f;

                        err = 0;
                        ipc6->tclass = tc;

                        break;
                    }

                case IPV6_DONTFRAG:
                    {
                        int df;

                        err = -EINVAL;
                        if (cmsg->cmsg_len != CMSG_LEN(sizeof(int)))
                                goto exit_f;

                        df = *(int *)CMSG_DATA(cmsg);
                        if (df < 0 || df > 1)
                                goto exit_f;

                        err = 0;
                        ipc6->dontfrag = df;

                        break;
                    }
                default:
                        net_dbg_ratelimited("invalid cmsg type: %d\n",
                                            cmsg->cmsg_type);
                        err = -EINVAL;
                        goto exit_f;
                }
        }

exit_f:
        return err;
}
EXPORT_SYMBOL_GPL(ip6_datagram_send_ctl);

void __ip6_dgram_sock_seq_show(struct seq_file *seq, struct sock *sp,
                               __u16 srcp, __u16 destp, int rqueue, int bucket)
{
        const struct in6_addr *dest, *src;

        dest  = &sp->sk_v6_daddr;
        src   = &sp->sk_v6_rcv_saddr;
        seq_printf(seq,
                   "%5d: %08X%08X%08X%08X:%04X %08X%08X%08X%08X:%04X "
                   "%02X %08X:%08X %02X:%08lX %08X %5u %8d %lu %d %pK %u\n",
                   bucket,
                   src->s6_addr32[0], src->s6_addr32[1],
                   src->s6_addr32[2], src->s6_addr32[3], srcp,
                   dest->s6_addr32[0], dest->s6_addr32[1],
                   dest->s6_addr32[2], dest->s6_addr32[3], destp,
                   sp->sk_state,
                   sk_wmem_alloc_get(sp),
                   rqueue,
                   0, 0L, 0,
                   from_kuid_munged(seq_user_ns(seq), sk_uid(sp)),
                   0,
                   sock_i_ino(sp),
                   refcount_read(&sp->sk_refcnt), sp,
                   sk_drops_read(sp));
}