Release 4.11 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;
}
Contributors
Person | Tokens | Prop | Commits | CommitProp |
Vasiliy Kulikov | 39 | 86.67% | 1 | 50.00% |
Eric Dumazet | 6 | 13.33% | 1 | 50.00% |
Total | 45 | 100.00% | 2 | 100.00% |
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)];
}
Contributors
Person | Tokens | Prop | Commits | CommitProp |
Vasiliy Kulikov | 38 | 97.44% | 1 | 50.00% |
Eric Dumazet | 1 | 2.56% | 1 | 50.00% |
Total | 39 | 100.00% | 2 | 100.00% |
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;
}
Contributors
Person | Tokens | Prop | Commits | CommitProp |
Vasiliy Kulikov | 315 | 99.37% | 1 | 50.00% |
Lorenzo Colitti | 2 | 0.63% | 1 | 50.00% |
Total | 317 | 100.00% | 2 | 100.00% |
EXPORT_SYMBOL_GPL(ping_get_port);
int 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." */
return 0;
}
Contributors
Person | Tokens | Prop | Commits | CommitProp |
Vasiliy Kulikov | 23 | 79.31% | 1 | 33.33% |
Craig Gallek | 4 | 13.79% | 1 | 33.33% |
Lorenzo Colitti | 2 | 6.90% | 1 | 33.33% |
Total | 29 | 100.00% | 3 | 100.00% |
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);
write_lock_bh(&ping_table.lock);
if (sk_hashed(sk)) {
hlist_nulls_del(&sk->sk_nulls_node);
sk_nulls_node_init(&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);
}
Contributors
Person | Tokens | Prop | Commits | CommitProp |
Vasiliy Kulikov | 83 | 79.81% | 1 | 20.00% |
Eric Dumazet | 11 | 10.58% | 2 | 40.00% |
David S. Miller | 8 | 7.69% | 1 | 20.00% |
Lorenzo Colitti | 2 | 1.92% | 1 | 20.00% |
Total | 104 | 100.00% | 5 | 100.00% |
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;
}
Contributors
Person | Tokens | Prop | Commits | CommitProp |
Lorenzo Colitti | 185 | 51.68% | 1 | 16.67% |
Vasiliy Kulikov | 160 | 44.69% | 1 | 16.67% |
Eric Dumazet | 9 | 2.51% | 3 | 50.00% |
Jane Zhou | 4 | 1.12% | 1 | 16.67% |
Total | 358 | 100.00% | 6 | 100.00% |
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));
}
Contributors
Person | Tokens | Prop | Commits | CommitProp |
Vasiliy Kulikov | 68 | 80.00% | 1 | 20.00% |
Eric W. Biedermann | 11 | 12.94% | 2 | 40.00% |
Américo Wang | 5 | 5.88% | 1 | 20.00% |
Eric Dumazet | 1 | 1.18% | 1 | 20.00% |
Total | 85 | 100.00% | 5 | 100.00% |
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;
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();
for (i = 0; i < group_info->ngroups; i++) {
kgid_t gid = group_info->gid[i];
if (gid_lte(low, gid) && gid_lte(gid, high))
goto out_release_group;
}
ret = -EACCES;
out_release_group:
put_group_info(group_info);
return ret;
}
Contributors
Person | Tokens | Prop | Commits | CommitProp |
Vasiliy Kulikov | 72 | 46.75% | 1 | 16.67% |
Eric W. Biedermann | 41 | 26.62% | 2 | 33.33% |
Wang, Xiaoming | 25 | 16.23% | 1 | 16.67% |
Lorenzo Colitti | 14 | 9.09% | 1 | 16.67% |
Alexey Dobriyan | 2 | 1.30% | 1 | 16.67% |
Total | 154 | 100.00% | 6 | 100.00% |
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);
}
Contributors
Person | Tokens | Prop | Commits | CommitProp |
Vasiliy Kulikov | 46 | 100.00% | 1 | 100.00% |
Total | 46 | 100.00% | 1 | 100.00% |
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 (!(net->ipv6.sysctl.ip_nonlocal_bind ||
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;
}
Contributors
Person | Tokens | Prop | Commits | CommitProp |
Lorenzo Colitti | 369 | 83.48% | 2 | 28.57% |
Vasiliy Kulikov | 49 | 11.09% | 1 | 14.29% |
Hannes Frederic Sowa | 11 | 2.49% | 1 | 14.29% |
Tom Herbert | 8 | 1.81% | 1 | 14.29% |
Vincent Bernat | 4 | 0.90% | 1 | 14.29% |
Fengguang Wu | 1 | 0.23% | 1 | 14.29% |
Total | 442 | 100.00% | 7 | 100.00% |
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
}
}
Contributors
Person | Tokens | Prop | Commits | CommitProp |
Lorenzo Colitti | 112 | 97.39% | 1 | 33.33% |
Eric Dumazet | 2 | 1.74% | 1 | 33.33% |
Fengguang Wu | 1 | 0.87% | 1 | 33.33% |
Total | 115 | 100.00% | 3 | 100.00% |
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
}
}
Contributors
Person | Tokens | Prop | Commits | CommitProp |
Lorenzo Colitti | 108 | 95.58% | 1 | 33.33% |
Eric Dumazet | 4 | 3.54% | 1 | 33.33% |
Fengguang Wu | 1 | 0.88% | 1 | 33.33% |
Total | 113 | 100.00% | 3 | 100.00% |
/*
* 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 = %hu, dif = %d\n",
isk->inet_num,
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;
}
Contributors
Person | Tokens | Prop | Commits | CommitProp |
Vasiliy Kulikov | 147 | 51.04% | 1 | 16.67% |
Lorenzo Colitti | 119 | 41.32% | 1 | 16.67% |
Eric Dumazet | 21 | 7.29% | 3 | 50.00% |
Gao Feng | 1 | 0.35% | 1 | 16.67% |
Total | 288 | 100.00% | 6 | 100.00% |
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);
}
Contributors
Person | Tokens | Prop | Commits | CommitProp |
Lorenzo Colitti | 23 | 51.11% | 1 | 50.00% |
Vasiliy Kulikov | 22 | 48.89% | 1 | 50.00% |
Total | 45 | 100.00% | 2 | 100.00% |
/*
* 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);
}
Contributors
Person | Tokens | Prop | Commits | CommitProp |
Vasiliy Kulikov | 322 | 55.33% | 1 | 20.00% |
Lorenzo Colitti | 243 | 41.75% | 1 | 20.00% |
David S. Miller | 16 | 2.75% | 2 | 40.00% |
Ian Morris | 1 | 0.17% | 1 | 20.00% |
Total | 582 | 100.00% | 5 | 100.00% |
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_full(to + sizeof(struct icmphdr),
fraglen, &pfh->wcheck,
&pfh->msg->msg_iter))
return -EFAULT;
} else if (offset < sizeof(struct icmphdr)) {