ipv4: coding style: comparison for inequality with NULL

[mirror_ubuntu-artful-kernel.git] / net / ipv4 / ping.c

/*
 * 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.
 *
 *              "Ping" sockets
 *
 *              This program is free software; you can redistribute it and/or
 *              modify it under the terms of the GNU General Public License
 *              as published by the Free Software Foundation; either version
 *              2 of the License, or (at your option) any later version.
 *
 * Based on ipv4/udp.c code.
 *
 * Authors:     Vasiliy Kulikov / Openwall (for Linux 2.6),
 *              Pavel Kankovsky (for Linux 2.4.32)
 *
 * Pavel gave all rights to bugs to Vasiliy,
 * none of the bugs are Pavel's now.
 *
 */

#include <linux/uaccess.h>
#include <linux/types.h>
#include <linux/fcntl.h>
#include <linux/socket.h>
#include <linux/sockios.h>
#include <linux/in.h>
#include <linux/errno.h>
#include <linux/timer.h>
#include <linux/mm.h>
#include <linux/inet.h>
#include <linux/netdevice.h>
#include <net/snmp.h>
#include <net/ip.h>
#include <net/icmp.h>
#include <net/protocol.h>
#include <linux/skbuff.h>
#include <linux/proc_fs.h>
#include <linux/export.h>
#include <net/sock.h>
#include <net/ping.h>
#include <net/udp.h>
#include <net/route.h>
#include <net/inet_common.h>
#include <net/checksum.h>

#if IS_ENABLED(CONFIG_IPV6)
#include <linux/in6.h>
#include <linux/icmpv6.h>
#include <net/addrconf.h>
#include <net/ipv6.h>
#include <net/transp_v6.h>
#endif

struct ping_table {
        struct hlist_nulls_head hash[PING_HTABLE_SIZE];
        rwlock_t                lock;
};

static struct ping_table ping_table;
struct pingv6_ops pingv6_ops;
EXPORT_SYMBOL_GPL(pingv6_ops);

static u16 ping_port_rover;

static inline u32 ping_hashfn(const struct net *net, u32 num, u32 mask)
{
        u32 res = (num + net_hash_mix(net)) & mask;

        pr_debug("hash(%u) = %u\n", num, res);
        return res;
}
EXPORT_SYMBOL_GPL(ping_hash);

static inline struct hlist_nulls_head *ping_hashslot(struct ping_table *table,
                                             struct net *net, unsigned int num)
{
        return &table->hash[ping_hashfn(net, num, PING_HTABLE_MASK)];
}

int ping_get_port(struct sock *sk, unsigned short ident)
{
        struct hlist_nulls_node *node;
        struct hlist_nulls_head *hlist;
        struct inet_sock *isk, *isk2;
        struct sock *sk2 = NULL;

        isk = inet_sk(sk);
        write_lock_bh(&ping_table.lock);
        if (ident == 0) {
                u32 i;
                u16 result = ping_port_rover + 1;

                for (i = 0; i < (1L << 16); i++, result++) {
                        if (!result)
                                result++; /* avoid zero */
                        hlist = ping_hashslot(&ping_table, sock_net(sk),
                                            result);
                        ping_portaddr_for_each_entry(sk2, node, hlist) {
                                isk2 = inet_sk(sk2);

                                if (isk2->inet_num == result)
                                        goto next_port;
                        }

                        /* found */
                        ping_port_rover = ident = result;
                        break;
next_port:
                        ;
                }
                if (i >= (1L << 16))
                        goto fail;
        } else {
                hlist = ping_hashslot(&ping_table, sock_net(sk), ident);
                ping_portaddr_for_each_entry(sk2, node, hlist) {
                        isk2 = inet_sk(sk2);

                        /* BUG? Why is this reuse and not reuseaddr? ping.c
                         * doesn't turn off SO_REUSEADDR, and it doesn't expect
                         * that other ping processes can steal its packets.
                         */
                        if ((isk2->inet_num == ident) &&
                            (sk2 != sk) &&
                            (!sk2->sk_reuse || !sk->sk_reuse))
                                goto fail;
                }
        }

        pr_debug("found port/ident = %d\n", ident);
        isk->inet_num = ident;
        if (sk_unhashed(sk)) {
                pr_debug("was not hashed\n");
                sock_hold(sk);
                hlist_nulls_add_head(&sk->sk_nulls_node, hlist);
                sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);
        }
        write_unlock_bh(&ping_table.lock);
        return 0;

fail:
        write_unlock_bh(&ping_table.lock);
        return 1;
}
EXPORT_SYMBOL_GPL(ping_get_port);

void ping_hash(struct sock *sk)
{
        pr_debug("ping_hash(sk->port=%u)\n", inet_sk(sk)->inet_num);
        BUG(); /* "Please do not press this button again." */
}

void ping_unhash(struct sock *sk)
{
        struct inet_sock *isk = inet_sk(sk);
        pr_debug("ping_unhash(isk=%p,isk->num=%u)\n", isk, isk->inet_num);
        if (sk_hashed(sk)) {
                write_lock_bh(&ping_table.lock);
                hlist_nulls_del(&sk->sk_nulls_node);
                sock_put(sk);
                isk->inet_num = 0;
                isk->inet_sport = 0;
                sock_prot_inuse_add(sock_net(sk), sk->sk_prot, -1);
                write_unlock_bh(&ping_table.lock);
        }
}
EXPORT_SYMBOL_GPL(ping_unhash);

static struct sock *ping_lookup(struct net *net, struct sk_buff *skb, u16 ident)
{
        struct hlist_nulls_head *hslot = ping_hashslot(&ping_table, net, ident);
        struct sock *sk = NULL;
        struct inet_sock *isk;
        struct hlist_nulls_node *hnode;
        int dif = skb->dev->ifindex;

        if (skb->protocol == htons(ETH_P_IP)) {
                pr_debug("try to find: num = %d, daddr = %pI4, dif = %d\n",
                         (int)ident, &ip_hdr(skb)->daddr, dif);
#if IS_ENABLED(CONFIG_IPV6)
        } else if (skb->protocol == htons(ETH_P_IPV6)) {
                pr_debug("try to find: num = %d, daddr = %pI6c, dif = %d\n",
                         (int)ident, &ipv6_hdr(skb)->daddr, dif);
#endif
        }

        read_lock_bh(&ping_table.lock);

        ping_portaddr_for_each_entry(sk, hnode, hslot) {
                isk = inet_sk(sk);

                pr_debug("iterate\n");
                if (isk->inet_num != ident)
                        continue;

                if (skb->protocol == htons(ETH_P_IP) &&
                    sk->sk_family == AF_INET) {
                        pr_debug("found: %p: num=%d, daddr=%pI4, dif=%d\n", sk,
                                 (int) isk->inet_num, &isk->inet_rcv_saddr,
                                 sk->sk_bound_dev_if);

                        if (isk->inet_rcv_saddr &&
                            isk->inet_rcv_saddr != ip_hdr(skb)->daddr)
                                continue;
#if IS_ENABLED(CONFIG_IPV6)
                } else if (skb->protocol == htons(ETH_P_IPV6) &&
                           sk->sk_family == AF_INET6) {

                        pr_debug("found: %p: num=%d, daddr=%pI6c, dif=%d\n", sk,
                                 (int) isk->inet_num,
                                 &sk->sk_v6_rcv_saddr,
                                 sk->sk_bound_dev_if);

                        if (!ipv6_addr_any(&sk->sk_v6_rcv_saddr) &&
                            !ipv6_addr_equal(&sk->sk_v6_rcv_saddr,
                                             &ipv6_hdr(skb)->daddr))
                                continue;
#endif
                } else {
                        continue;
                }

                if (sk->sk_bound_dev_if && sk->sk_bound_dev_if != dif)
                        continue;

                sock_hold(sk);
                goto exit;
        }

        sk = NULL;
exit:
        read_unlock_bh(&ping_table.lock);

        return sk;
}

static void inet_get_ping_group_range_net(struct net *net, kgid_t *low,
                                          kgid_t *high)
{
        kgid_t *data = net->ipv4.ping_group_range.range;
        unsigned int seq;

        do {
                seq = read_seqbegin(&net->ipv4.ping_group_range.lock);

                *low = data[0];
                *high = data[1];
        } while (read_seqretry(&net->ipv4.ping_group_range.lock, seq));
}


int ping_init_sock(struct sock *sk)
{
        struct net *net = sock_net(sk);
        kgid_t group = current_egid();
        struct group_info *group_info;
        int i, j, count;
        kgid_t low, high;
        int ret = 0;

        if (sk->sk_family == AF_INET6)
                sk->sk_ipv6only = 1;

        inet_get_ping_group_range_net(net, &low, &high);
        if (gid_lte(low, group) && gid_lte(group, high))
                return 0;

        group_info = get_current_groups();
        count = group_info->ngroups;
        for (i = 0; i < group_info->nblocks; i++) {
                int cp_count = min_t(int, NGROUPS_PER_BLOCK, count);
                for (j = 0; j < cp_count; j++) {
                        kgid_t gid = group_info->blocks[i][j];
                        if (gid_lte(low, gid) && gid_lte(gid, high))
                                goto out_release_group;
                }

                count -= cp_count;
        }

        ret = -EACCES;

out_release_group:
        put_group_info(group_info);
        return ret;
}
EXPORT_SYMBOL_GPL(ping_init_sock);

void ping_close(struct sock *sk, long timeout)
{
        pr_debug("ping_close(sk=%p,sk->num=%u)\n",
                 inet_sk(sk), inet_sk(sk)->inet_num);
        pr_debug("isk->refcnt = %d\n", sk->sk_refcnt.counter);

        sk_common_release(sk);
}
EXPORT_SYMBOL_GPL(ping_close);

/* Checks the bind address and possibly modifies sk->sk_bound_dev_if. */
static int ping_check_bind_addr(struct sock *sk, struct inet_sock *isk,
                                struct sockaddr *uaddr, int addr_len) {
        struct net *net = sock_net(sk);
        if (sk->sk_family == AF_INET) {
                struct sockaddr_in *addr = (struct sockaddr_in *) uaddr;
                int chk_addr_ret;

                if (addr_len < sizeof(*addr))
                        return -EINVAL;

                if (addr->sin_family != AF_INET &&
                    !(addr->sin_family == AF_UNSPEC &&
                      addr->sin_addr.s_addr == htonl(INADDR_ANY)))
                        return -EAFNOSUPPORT;

                pr_debug("ping_check_bind_addr(sk=%p,addr=%pI4,port=%d)\n",
                         sk, &addr->sin_addr.s_addr, ntohs(addr->sin_port));

                chk_addr_ret = inet_addr_type(net, addr->sin_addr.s_addr);

                if (addr->sin_addr.s_addr == htonl(INADDR_ANY))
                        chk_addr_ret = RTN_LOCAL;

                if ((net->ipv4.sysctl_ip_nonlocal_bind == 0 &&
                    isk->freebind == 0 && isk->transparent == 0 &&
                     chk_addr_ret != RTN_LOCAL) ||
                    chk_addr_ret == RTN_MULTICAST ||
                    chk_addr_ret == RTN_BROADCAST)
                        return -EADDRNOTAVAIL;

#if IS_ENABLED(CONFIG_IPV6)
        } else if (sk->sk_family == AF_INET6) {
                struct sockaddr_in6 *addr = (struct sockaddr_in6 *) uaddr;
                int addr_type, scoped, has_addr;
                struct net_device *dev = NULL;

                if (addr_len < sizeof(*addr))
                        return -EINVAL;

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

                pr_debug("ping_check_bind_addr(sk=%p,addr=%pI6c,port=%d)\n",
                         sk, addr->sin6_addr.s6_addr, ntohs(addr->sin6_port));

                addr_type = ipv6_addr_type(&addr->sin6_addr);
                scoped = __ipv6_addr_needs_scope_id(addr_type);
                if ((addr_type != IPV6_ADDR_ANY &&
                     !(addr_type & IPV6_ADDR_UNICAST)) ||
                    (scoped && !addr->sin6_scope_id))
                        return -EINVAL;

                rcu_read_lock();
                if (addr->sin6_scope_id) {
                        dev = dev_get_by_index_rcu(net, addr->sin6_scope_id);
                        if (!dev) {
                                rcu_read_unlock();
                                return -ENODEV;
                        }
                }
                has_addr = pingv6_ops.ipv6_chk_addr(net, &addr->sin6_addr, dev,
                                                    scoped);
                rcu_read_unlock();

                if (!(isk->freebind || isk->transparent || has_addr ||
                      addr_type == IPV6_ADDR_ANY))
                        return -EADDRNOTAVAIL;

                if (scoped)
                        sk->sk_bound_dev_if = addr->sin6_scope_id;
#endif
        } else {
                return -EAFNOSUPPORT;
        }
        return 0;
}

static void ping_set_saddr(struct sock *sk, struct sockaddr *saddr)
{
        if (saddr->sa_family == AF_INET) {
                struct inet_sock *isk = inet_sk(sk);
                struct sockaddr_in *addr = (struct sockaddr_in *) saddr;
                isk->inet_rcv_saddr = isk->inet_saddr = addr->sin_addr.s_addr;
#if IS_ENABLED(CONFIG_IPV6)
        } else if (saddr->sa_family == AF_INET6) {
                struct sockaddr_in6 *addr = (struct sockaddr_in6 *) saddr;
                struct ipv6_pinfo *np = inet6_sk(sk);
                sk->sk_v6_rcv_saddr = np->saddr = addr->sin6_addr;
#endif
        }
}

static void ping_clear_saddr(struct sock *sk, int dif)
{
        sk->sk_bound_dev_if = dif;
        if (sk->sk_family == AF_INET) {
                struct inet_sock *isk = inet_sk(sk);
                isk->inet_rcv_saddr = isk->inet_saddr = 0;
#if IS_ENABLED(CONFIG_IPV6)
        } else if (sk->sk_family == AF_INET6) {
                struct ipv6_pinfo *np = inet6_sk(sk);
                memset(&sk->sk_v6_rcv_saddr, 0, sizeof(sk->sk_v6_rcv_saddr));
                memset(&np->saddr, 0, sizeof(np->saddr));
#endif
        }
}
/*
 * We need our own bind because there are no privileged id's == local ports.
 * Moreover, we don't allow binding to multi- and broadcast addresses.
 */

int ping_bind(struct sock *sk, struct sockaddr *uaddr, int addr_len)
{
        struct inet_sock *isk = inet_sk(sk);
        unsigned short snum;
        int err;
        int dif = sk->sk_bound_dev_if;

        err = ping_check_bind_addr(sk, isk, uaddr, addr_len);
        if (err)
                return err;

        lock_sock(sk);

        err = -EINVAL;
        if (isk->inet_num != 0)
                goto out;

        err = -EADDRINUSE;
        ping_set_saddr(sk, uaddr);
        snum = ntohs(((struct sockaddr_in *)uaddr)->sin_port);
        if (ping_get_port(sk, snum) != 0) {
                ping_clear_saddr(sk, dif);
                goto out;
        }

        pr_debug("after bind(): num = %d, dif = %d\n",
                 (int)isk->inet_num,
                 (int)sk->sk_bound_dev_if);

        err = 0;
        if (sk->sk_family == AF_INET && isk->inet_rcv_saddr)
                sk->sk_userlocks |= SOCK_BINDADDR_LOCK;
#if IS_ENABLED(CONFIG_IPV6)
        if (sk->sk_family == AF_INET6 && !ipv6_addr_any(&sk->sk_v6_rcv_saddr))
                sk->sk_userlocks |= SOCK_BINDADDR_LOCK;
#endif

        if (snum)
                sk->sk_userlocks |= SOCK_BINDPORT_LOCK;
        isk->inet_sport = htons(isk->inet_num);
        isk->inet_daddr = 0;
        isk->inet_dport = 0;

#if IS_ENABLED(CONFIG_IPV6)
        if (sk->sk_family == AF_INET6)
                memset(&sk->sk_v6_daddr, 0, sizeof(sk->sk_v6_daddr));
#endif

        sk_dst_reset(sk);
out:
        release_sock(sk);
        pr_debug("ping_v4_bind -> %d\n", err);
        return err;
}
EXPORT_SYMBOL_GPL(ping_bind);

/*
 * Is this a supported type of ICMP message?
 */

static inline int ping_supported(int family, int type, int code)
{
        return (family == AF_INET && type == ICMP_ECHO && code == 0) ||
               (family == AF_INET6 && type == ICMPV6_ECHO_REQUEST && code == 0);
}

/*
 * This routine is called by the ICMP module when it gets some
 * sort of error condition.
 */

void ping_err(struct sk_buff *skb, int offset, u32 info)
{
        int family;
        struct icmphdr *icmph;
        struct inet_sock *inet_sock;
        int type;
        int code;
        struct net *net = dev_net(skb->dev);
        struct sock *sk;
        int harderr;
        int err;

        if (skb->protocol == htons(ETH_P_IP)) {
                family = AF_INET;
                type = icmp_hdr(skb)->type;
                code = icmp_hdr(skb)->code;
                icmph = (struct icmphdr *)(skb->data + offset);
        } else if (skb->protocol == htons(ETH_P_IPV6)) {
                family = AF_INET6;
                type = icmp6_hdr(skb)->icmp6_type;
                code = icmp6_hdr(skb)->icmp6_code;
                icmph = (struct icmphdr *) (skb->data + offset);
        } else {
                BUG();
        }

        /* We assume the packet has already been checked by icmp_unreach */

        if (!ping_supported(family, icmph->type, icmph->code))
                return;

        pr_debug("ping_err(proto=0x%x,type=%d,code=%d,id=%04x,seq=%04x)\n",
                 skb->protocol, type, code, ntohs(icmph->un.echo.id),
                 ntohs(icmph->un.echo.sequence));

        sk = ping_lookup(net, skb, ntohs(icmph->un.echo.id));
        if (!sk) {
                pr_debug("no socket, dropping\n");
                return; /* No socket for error */
        }
        pr_debug("err on socket %p\n", sk);

        err = 0;
        harderr = 0;
        inet_sock = inet_sk(sk);

        if (skb->protocol == htons(ETH_P_IP)) {
                switch (type) {
                default:
                case ICMP_TIME_EXCEEDED:
                        err = EHOSTUNREACH;
                        break;
                case ICMP_SOURCE_QUENCH:
                        /* This is not a real error but ping wants to see it.
                         * Report it with some fake errno.
                         */
                        err = EREMOTEIO;
                        break;
                case ICMP_PARAMETERPROB:
                        err = EPROTO;
                        harderr = 1;
                        break;
                case ICMP_DEST_UNREACH:
                        if (code == ICMP_FRAG_NEEDED) { /* Path MTU discovery */
                                ipv4_sk_update_pmtu(skb, sk, info);
                                if (inet_sock->pmtudisc != IP_PMTUDISC_DONT) {
                                        err = EMSGSIZE;
                                        harderr = 1;
                                        break;
                                }
                                goto out;
                        }
                        err = EHOSTUNREACH;
                        if (code <= NR_ICMP_UNREACH) {
                                harderr = icmp_err_convert[code].fatal;
                                err = icmp_err_convert[code].errno;
                        }
                        break;
                case ICMP_REDIRECT:
                        /* See ICMP_SOURCE_QUENCH */
                        ipv4_sk_redirect(skb, sk);
                        err = EREMOTEIO;
                        break;
                }
#if IS_ENABLED(CONFIG_IPV6)
        } else if (skb->protocol == htons(ETH_P_IPV6)) {
                harderr = pingv6_ops.icmpv6_err_convert(type, code, &err);
#endif
        }

        /*
         *      RFC1122: OK.  Passes ICMP errors back to application, as per
         *      4.1.3.3.
         */
        if ((family == AF_INET && !inet_sock->recverr) ||
            (family == AF_INET6 && !inet6_sk(sk)->recverr)) {
                if (!harderr || sk->sk_state != TCP_ESTABLISHED)
                        goto out;
        } else {
                if (family == AF_INET) {
                        ip_icmp_error(sk, skb, err, 0 /* no remote port */,
                                      info, (u8 *)icmph);
#if IS_ENABLED(CONFIG_IPV6)
                } else if (family == AF_INET6) {
                        pingv6_ops.ipv6_icmp_error(sk, skb, err, 0,
                                                   info, (u8 *)icmph);
#endif
                }
        }
        sk->sk_err = err;
        sk->sk_error_report(sk);
out:
        sock_put(sk);
}
EXPORT_SYMBOL_GPL(ping_err);

/*
 *      Copy and checksum an ICMP Echo packet from user space into a buffer
 *      starting from the payload.
 */

int ping_getfrag(void *from, char *to,
                 int offset, int fraglen, int odd, struct sk_buff *skb)
{
        struct pingfakehdr *pfh = (struct pingfakehdr *)from;

        if (offset == 0) {
                fraglen -= sizeof(struct icmphdr);
                if (fraglen < 0)
                        BUG();
                if (csum_and_copy_from_iter(to + sizeof(struct icmphdr),
                            fraglen, &pfh->wcheck,
                            &pfh->msg->msg_iter) != fraglen)
                        return -EFAULT;
        } else if (offset < sizeof(struct icmphdr)) {
                        BUG();
        } else {
                if (csum_and_copy_from_iter(to, fraglen, &pfh->wcheck,
                                            &pfh->msg->msg_iter) != fraglen)
                        return -EFAULT;
        }

#if IS_ENABLED(CONFIG_IPV6)
        /* For IPv6, checksum each skb as we go along, as expected by
         * icmpv6_push_pending_frames. For IPv4, accumulate the checksum in
         * wcheck, it will be finalized in ping_v4_push_pending_frames.
         */
        if (pfh->family == AF_INET6) {
                skb->csum = pfh->wcheck;
                skb->ip_summed = CHECKSUM_NONE;
                pfh->wcheck = 0;
        }
#endif

        return 0;
}
EXPORT_SYMBOL_GPL(ping_getfrag);

static int ping_v4_push_pending_frames(struct sock *sk, struct pingfakehdr *pfh,
                                       struct flowi4 *fl4)
{
        struct sk_buff *skb = skb_peek(&sk->sk_write_queue);

        pfh->wcheck = csum_partial((char *)&pfh->icmph,
                sizeof(struct icmphdr), pfh->wcheck);
        pfh->icmph.checksum = csum_fold(pfh->wcheck);
        memcpy(icmp_hdr(skb), &pfh->icmph, sizeof(struct icmphdr));
        skb->ip_summed = CHECKSUM_NONE;
        return ip_push_pending_frames(sk, fl4);
}

int ping_common_sendmsg(int family, struct msghdr *msg, size_t len,
                        void *user_icmph, size_t icmph_len) {
        u8 type, code;

        if (len > 0xFFFF)
                return -EMSGSIZE;

        /*
         *      Check the flags.
         */

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

        /*
         *      Fetch the ICMP header provided by the userland.
         *      iovec is modified! The ICMP header is consumed.
         */
        if (memcpy_from_msg(user_icmph, msg, icmph_len))
                return -EFAULT;

        if (family == AF_INET) {
                type = ((struct icmphdr *) user_icmph)->type;
                code = ((struct icmphdr *) user_icmph)->code;
#if IS_ENABLED(CONFIG_IPV6)
        } else if (family == AF_INET6) {
                type = ((struct icmp6hdr *) user_icmph)->icmp6_type;
                code = ((struct icmp6hdr *) user_icmph)->icmp6_code;
#endif
        } else {
                BUG();
        }

        if (!ping_supported(family, type, code))
                return -EINVAL;

        return 0;
}
EXPORT_SYMBOL_GPL(ping_common_sendmsg);

static int ping_v4_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
{
        struct net *net = sock_net(sk);
        struct flowi4 fl4;
        struct inet_sock *inet = inet_sk(sk);
        struct ipcm_cookie ipc;
        struct icmphdr user_icmph;
        struct pingfakehdr pfh;
        struct rtable *rt = NULL;
        struct ip_options_data opt_copy;
        int free = 0;
        __be32 saddr, daddr, faddr;
        u8  tos;
        int err;

        pr_debug("ping_v4_sendmsg(sk=%p,sk->num=%u)\n", inet, inet->inet_num);

        err = ping_common_sendmsg(AF_INET, msg, len, &user_icmph,
                                  sizeof(user_icmph));
        if (err)
                return err;

        /*
         *      Get and verify the address.
         */

        if (msg->msg_name) {
                DECLARE_SOCKADDR(struct sockaddr_in *, usin, msg->msg_name);
                if (msg->msg_namelen < sizeof(*usin))
                        return -EINVAL;
                if (usin->sin_family != AF_INET)
                        return -EAFNOSUPPORT;
                daddr = usin->sin_addr.s_addr;
                /* no remote port */
        } else {
                if (sk->sk_state != TCP_ESTABLISHED)
                        return -EDESTADDRREQ;
                daddr = inet->inet_daddr;
                /* no remote port */
        }

        ipc.addr = inet->inet_saddr;
        ipc.opt = NULL;
        ipc.oif = sk->sk_bound_dev_if;
        ipc.tx_flags = 0;
        ipc.ttl = 0;
        ipc.tos = -1;

        sock_tx_timestamp(sk, &ipc.tx_flags);

        if (msg->msg_controllen) {
                err = ip_cmsg_send(sock_net(sk), msg, &ipc, false);
                if (err)
                        return err;
                if (ipc.opt)
                        free = 1;
        }
        if (!ipc.opt) {
                struct ip_options_rcu *inet_opt;

                rcu_read_lock();
                inet_opt = rcu_dereference(inet->inet_opt);
                if (inet_opt) {
                        memcpy(&opt_copy, inet_opt,
                               sizeof(*inet_opt) + inet_opt->opt.optlen);
                        ipc.opt = &opt_copy.opt;
                }
                rcu_read_unlock();
        }

        saddr = ipc.addr;
        ipc.addr = faddr = daddr;

        if (ipc.opt && ipc.opt->opt.srr) {
                if (!daddr)
                        return -EINVAL;
                faddr = ipc.opt->opt.faddr;
        }
        tos = get_rttos(&ipc, inet);
        if (sock_flag(sk, SOCK_LOCALROUTE) ||
            (msg->msg_flags & MSG_DONTROUTE) ||
            (ipc.opt && ipc.opt->opt.is_strictroute)) {
                tos |= RTO_ONLINK;
        }

        if (ipv4_is_multicast(daddr)) {
                if (!ipc.oif)
                        ipc.oif = inet->mc_index;
                if (!saddr)
                        saddr = inet->mc_addr;
        } else if (!ipc.oif)
                ipc.oif = inet->uc_index;

        flowi4_init_output(&fl4, ipc.oif, sk->sk_mark, tos,
                           RT_SCOPE_UNIVERSE, sk->sk_protocol,
                           inet_sk_flowi_flags(sk), faddr, saddr, 0, 0);

        security_sk_classify_flow(sk, flowi4_to_flowi(&fl4));
        rt = ip_route_output_flow(net, &fl4, sk);
        if (IS_ERR(rt)) {
                err = PTR_ERR(rt);
                rt = NULL;
                if (err == -ENETUNREACH)
                        IP_INC_STATS(net, IPSTATS_MIB_OUTNOROUTES);
                goto out;
        }

        err = -EACCES;
        if ((rt->rt_flags & RTCF_BROADCAST) &&
            !sock_flag(sk, SOCK_BROADCAST))
                goto out;

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

        if (!ipc.addr)
                ipc.addr = fl4.daddr;

        lock_sock(sk);

        pfh.icmph.type = user_icmph.type; /* already checked */
        pfh.icmph.code = user_icmph.code; /* ditto */
        pfh.icmph.checksum = 0;
        pfh.icmph.un.echo.id = inet->inet_sport;
        pfh.icmph.un.echo.sequence = user_icmph.un.echo.sequence;
        pfh.msg = msg;
        pfh.wcheck = 0;
        pfh.family = AF_INET;

        err = ip_append_data(sk, &fl4, ping_getfrag, &pfh, len,
                        0, &ipc, &rt, msg->msg_flags);
        if (err)
                ip_flush_pending_frames(sk);
        else
                err = ping_v4_push_pending_frames(sk, &pfh, &fl4);
        release_sock(sk);

out:
        ip_rt_put(rt);
        if (free)
                kfree(ipc.opt);
        if (!err) {
                icmp_out_count(sock_net(sk), user_icmph.type);
                return len;
        }
        return err;

do_confirm:
        dst_confirm(&rt->dst);
        if (!(msg->msg_flags & MSG_PROBE) || len)
                goto back_from_confirm;
        err = 0;
        goto out;
}

int ping_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, int noblock,
                 int flags, int *addr_len)
{
        struct inet_sock *isk = inet_sk(sk);
        int family = sk->sk_family;
        struct sk_buff *skb;
        int copied, err;

        pr_debug("ping_recvmsg(sk=%p,sk->num=%u)\n", isk, isk->inet_num);

        err = -EOPNOTSUPP;
        if (flags & MSG_OOB)
                goto out;

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

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

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

        /* Don't bother checking the checksum */
        err = skb_copy_datagram_msg(skb, 0, msg, copied);
        if (err)
                goto done;

        sock_recv_timestamp(msg, sk, skb);

        /* Copy the address and add cmsg data. */
        if (family == AF_INET) {
                DECLARE_SOCKADDR(struct sockaddr_in *, sin, msg->msg_name);

                if (sin) {
                        sin->sin_family = AF_INET;
                        sin->sin_port = 0 /* skb->h.uh->source */;
                        sin->sin_addr.s_addr = ip_hdr(skb)->saddr;
                        memset(sin->sin_zero, 0, sizeof(sin->sin_zero));
                        *addr_len = sizeof(*sin);
                }

                if (isk->cmsg_flags)
                        ip_cmsg_recv(msg, skb);

#if IS_ENABLED(CONFIG_IPV6)
        } else if (family == AF_INET6) {
                struct ipv6_pinfo *np = inet6_sk(sk);
                struct ipv6hdr *ip6 = ipv6_hdr(skb);
                DECLARE_SOCKADDR(struct sockaddr_in6 *, sin6, msg->msg_name);

                if (sin6) {
                        sin6->sin6_family = AF_INET6;
                        sin6->sin6_port = 0;
                        sin6->sin6_addr = ip6->saddr;
                        sin6->sin6_flowinfo = 0;
                        if (np->sndflow)
                                sin6->sin6_flowinfo = ip6_flowinfo(ip6);
                        sin6->sin6_scope_id =
                                ipv6_iface_scope_id(&sin6->sin6_addr,
                                                    inet6_iif(skb));
                        *addr_len = sizeof(*sin6);
                }

                if (inet6_sk(sk)->rxopt.all)
                        pingv6_ops.ip6_datagram_recv_common_ctl(sk, msg, skb);
                if (skb->protocol == htons(ETH_P_IPV6) &&
                    inet6_sk(sk)->rxopt.all)
                        pingv6_ops.ip6_datagram_recv_specific_ctl(sk, msg, skb);
                else if (skb->protocol == htons(ETH_P_IP) && isk->cmsg_flags)
                        ip_cmsg_recv(msg, skb);
#endif
        } else {
                BUG();
        }

        err = copied;

done:
        skb_free_datagram(sk, skb);
out:
        pr_debug("ping_recvmsg -> %d\n", err);
        return err;
}
EXPORT_SYMBOL_GPL(ping_recvmsg);

int ping_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
{
        pr_debug("ping_queue_rcv_skb(sk=%p,sk->num=%d,skb=%p)\n",
                 inet_sk(sk), inet_sk(sk)->inet_num, skb);
        if (sock_queue_rcv_skb(sk, skb) < 0) {
                kfree_skb(skb);
                pr_debug("ping_queue_rcv_skb -> failed\n");
                return -1;
        }
        return 0;
}
EXPORT_SYMBOL_GPL(ping_queue_rcv_skb);


/*
 *      All we need to do is get the socket.
 */

bool ping_rcv(struct sk_buff *skb)
{
        struct sock *sk;
        struct net *net = dev_net(skb->dev);
        struct icmphdr *icmph = icmp_hdr(skb);

        /* We assume the packet has already been checked by icmp_rcv */

        pr_debug("ping_rcv(skb=%p,id=%04x,seq=%04x)\n",
                 skb, ntohs(icmph->un.echo.id), ntohs(icmph->un.echo.sequence));

        /* Push ICMP header back */
        skb_push(skb, skb->data - (u8 *)icmph);

        sk = ping_lookup(net, skb, ntohs(icmph->un.echo.id));
        if (sk) {
                struct sk_buff *skb2 = skb_clone(skb, GFP_ATOMIC);

                pr_debug("rcv on socket %p\n", sk);
                if (skb2)
                        ping_queue_rcv_skb(sk, skb2);
                sock_put(sk);
                return true;
        }
        pr_debug("no socket, dropping\n");

        return false;
}
EXPORT_SYMBOL_GPL(ping_rcv);

struct proto ping_prot = {
        .name =         "PING",
        .owner =        THIS_MODULE,
        .init =         ping_init_sock,
        .close =        ping_close,
        .connect =      ip4_datagram_connect,
        .disconnect =   udp_disconnect,
        .setsockopt =   ip_setsockopt,
        .getsockopt =   ip_getsockopt,
        .sendmsg =      ping_v4_sendmsg,
        .recvmsg =      ping_recvmsg,
        .bind =         ping_bind,
        .backlog_rcv =  ping_queue_rcv_skb,
        .release_cb =   ip4_datagram_release_cb,
        .hash =         ping_hash,
        .unhash =       ping_unhash,
        .get_port =     ping_get_port,
        .obj_size =     sizeof(struct inet_sock),
};
EXPORT_SYMBOL(ping_prot);

#ifdef CONFIG_PROC_FS

static struct sock *ping_get_first(struct seq_file *seq, int start)
{
        struct sock *sk;
        struct ping_iter_state *state = seq->private;
        struct net *net = seq_file_net(seq);

        for (state->bucket = start; state->bucket < PING_HTABLE_SIZE;
             ++state->bucket) {
                struct hlist_nulls_node *node;
                struct hlist_nulls_head *hslot;

                hslot = &ping_table.hash[state->bucket];

                if (hlist_nulls_empty(hslot))
                        continue;

                sk_nulls_for_each(sk, node, hslot) {
                        if (net_eq(sock_net(sk), net) &&
                            sk->sk_family == state->family)
                                goto found;
                }
        }
        sk = NULL;
found:
        return sk;
}

static struct sock *ping_get_next(struct seq_file *seq, struct sock *sk)
{
        struct ping_iter_state *state = seq->private;
        struct net *net = seq_file_net(seq);

        do {
                sk = sk_nulls_next(sk);
        } while (sk && (!net_eq(sock_net(sk), net)));

        if (!sk)
                return ping_get_first(seq, state->bucket + 1);
        return sk;
}

static struct sock *ping_get_idx(struct seq_file *seq, loff_t pos)
{
        struct sock *sk = ping_get_first(seq, 0);

        if (sk)
                while (pos && (sk = ping_get_next(seq, sk)) != NULL)
                        --pos;
        return pos ? NULL : sk;
}

void *ping_seq_start(struct seq_file *seq, loff_t *pos, sa_family_t family)
{
        struct ping_iter_state *state = seq->private;
        state->bucket = 0;
        state->family = family;

        read_lock_bh(&ping_table.lock);

        return *pos ? ping_get_idx(seq, *pos-1) : SEQ_START_TOKEN;
}
EXPORT_SYMBOL_GPL(ping_seq_start);

static void *ping_v4_seq_start(struct seq_file *seq, loff_t *pos)
{
        return ping_seq_start(seq, pos, AF_INET);
}

void *ping_seq_next(struct seq_file *seq, void *v, loff_t *pos)
{
        struct sock *sk;

        if (v == SEQ_START_TOKEN)
                sk = ping_get_idx(seq, 0);
        else
                sk = ping_get_next(seq, v);

        ++*pos;
        return sk;
}
EXPORT_SYMBOL_GPL(ping_seq_next);

void ping_seq_stop(struct seq_file *seq, void *v)
{
        read_unlock_bh(&ping_table.lock);
}
EXPORT_SYMBOL_GPL(ping_seq_stop);

static void ping_v4_format_sock(struct sock *sp, struct seq_file *f,
                int bucket)
{
        struct inet_sock *inet = inet_sk(sp);
        __be32 dest = inet->inet_daddr;
        __be32 src = inet->inet_rcv_saddr;
        __u16 destp = ntohs(inet->inet_dport);
        __u16 srcp = ntohs(inet->inet_sport);

        seq_printf(f, "%5d: %08X:%04X %08X:%04X"
                " %02X %08X:%08X %02X:%08lX %08X %5u %8d %lu %d %pK %d",
                bucket, src, srcp, dest, destp, sp->sk_state,
                sk_wmem_alloc_get(sp),
                sk_rmem_alloc_get(sp),
                0, 0L, 0,
                from_kuid_munged(seq_user_ns(f), sock_i_uid(sp)),
                0, sock_i_ino(sp),
                atomic_read(&sp->sk_refcnt), sp,
                atomic_read(&sp->sk_drops));
}

static int ping_v4_seq_show(struct seq_file *seq, void *v)
{
        seq_setwidth(seq, 127);
        if (v == SEQ_START_TOKEN)
                seq_puts(seq, "  sl  local_address rem_address   st tx_queue "
                           "rx_queue tr tm->when retrnsmt   uid  timeout "
                           "inode ref pointer drops");
        else {
                struct ping_iter_state *state = seq->private;

                ping_v4_format_sock(v, seq, state->bucket);
        }
        seq_pad(seq, '\n');
        return 0;
}

static const struct seq_operations ping_v4_seq_ops = {
        .show           = ping_v4_seq_show,
        .start          = ping_v4_seq_start,
        .next           = ping_seq_next,
        .stop           = ping_seq_stop,
};

static int ping_seq_open(struct inode *inode, struct file *file)
{
        struct ping_seq_afinfo *afinfo = PDE_DATA(inode);
        return seq_open_net(inode, file, &afinfo->seq_ops,
                           sizeof(struct ping_iter_state));
}

const struct file_operations ping_seq_fops = {
        .open           = ping_seq_open,
        .read           = seq_read,
        .llseek         = seq_lseek,
        .release        = seq_release_net,
};
EXPORT_SYMBOL_GPL(ping_seq_fops);

static struct ping_seq_afinfo ping_v4_seq_afinfo = {
        .name           = "icmp",
        .family         = AF_INET,
        .seq_fops       = &ping_seq_fops,
        .seq_ops        = {
                .start          = ping_v4_seq_start,
                .show           = ping_v4_seq_show,
                .next           = ping_seq_next,
                .stop           = ping_seq_stop,
        },
};

int ping_proc_register(struct net *net, struct ping_seq_afinfo *afinfo)
{
        struct proc_dir_entry *p;
        p = proc_create_data(afinfo->name, S_IRUGO, net->proc_net,
                             afinfo->seq_fops, afinfo);
        if (!p)
                return -ENOMEM;
        return 0;
}
EXPORT_SYMBOL_GPL(ping_proc_register);

void ping_proc_unregister(struct net *net, struct ping_seq_afinfo *afinfo)
{
        remove_proc_entry(afinfo->name, net->proc_net);
}
EXPORT_SYMBOL_GPL(ping_proc_unregister);

static int __net_init ping_v4_proc_init_net(struct net *net)
{
        return ping_proc_register(net, &ping_v4_seq_afinfo);
}

static void __net_exit ping_v4_proc_exit_net(struct net *net)
{
        ping_proc_unregister(net, &ping_v4_seq_afinfo);
}

static struct pernet_operations ping_v4_net_ops = {
        .init = ping_v4_proc_init_net,
        .exit = ping_v4_proc_exit_net,
};

int __init ping_proc_init(void)
{
        return register_pernet_subsys(&ping_v4_net_ops);
}

void ping_proc_exit(void)
{
        unregister_pernet_subsys(&ping_v4_net_ops);
}

#endif

void __init ping_init(void)
{
        int i;

        for (i = 0; i < PING_HTABLE_SIZE; i++)
                INIT_HLIST_NULLS_HEAD(&ping_table.hash[i], i);
        rwlock_init(&ping_table.lock);
}