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-rw-r--r--net/ipv4/icmp.c1393
1 files changed, 1393 insertions, 0 deletions
diff --git a/net/ipv4/icmp.c b/net/ipv4/icmp.c
new file mode 100644
index 000000000..0bbc047e8
--- /dev/null
+++ b/net/ipv4/icmp.c
@@ -0,0 +1,1393 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * NET3: Implementation of the ICMP protocol layer.
+ *
+ * Alan Cox, <alan@lxorguk.ukuu.org.uk>
+ *
+ * Some of the function names and the icmp unreach table for this
+ * module were derived from [icmp.c 1.0.11 06/02/93] by
+ * Ross Biro, Fred N. van Kempen, Mark Evans, Alan Cox, Gerhard Koerting.
+ * Other than that this module is a complete rewrite.
+ *
+ * Fixes:
+ * Clemens Fruhwirth : introduce global icmp rate limiting
+ * with icmp type masking ability instead
+ * of broken per type icmp timeouts.
+ * Mike Shaver : RFC1122 checks.
+ * Alan Cox : Multicast ping reply as self.
+ * Alan Cox : Fix atomicity lockup in ip_build_xmit
+ * call.
+ * Alan Cox : Added 216,128 byte paths to the MTU
+ * code.
+ * Martin Mares : RFC1812 checks.
+ * Martin Mares : Can be configured to follow redirects
+ * if acting as a router _without_ a
+ * routing protocol (RFC 1812).
+ * Martin Mares : Echo requests may be configured to
+ * be ignored (RFC 1812).
+ * Martin Mares : Limitation of ICMP error message
+ * transmit rate (RFC 1812).
+ * Martin Mares : TOS and Precedence set correctly
+ * (RFC 1812).
+ * Martin Mares : Now copying as much data from the
+ * original packet as we can without
+ * exceeding 576 bytes (RFC 1812).
+ * Willy Konynenberg : Transparent proxying support.
+ * Keith Owens : RFC1191 correction for 4.2BSD based
+ * path MTU bug.
+ * Thomas Quinot : ICMP Dest Unreach codes up to 15 are
+ * valid (RFC 1812).
+ * Andi Kleen : Check all packet lengths properly
+ * and moved all kfree_skb() up to
+ * icmp_rcv.
+ * Andi Kleen : Move the rate limit bookkeeping
+ * into the dest entry and use a token
+ * bucket filter (thanks to ANK). Make
+ * the rates sysctl configurable.
+ * Yu Tianli : Fixed two ugly bugs in icmp_send
+ * - IP option length was accounted wrongly
+ * - ICMP header length was not accounted
+ * at all.
+ * Tristan Greaves : Added sysctl option to ignore bogus
+ * broadcast responses from broken routers.
+ *
+ * To Fix:
+ *
+ * - Should use skb_pull() instead of all the manual checking.
+ * This would also greatly simply some upper layer error handlers. --AK
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/module.h>
+#include <linux/types.h>
+#include <linux/jiffies.h>
+#include <linux/kernel.h>
+#include <linux/fcntl.h>
+#include <linux/socket.h>
+#include <linux/in.h>
+#include <linux/inet.h>
+#include <linux/inetdevice.h>
+#include <linux/netdevice.h>
+#include <linux/string.h>
+#include <linux/netfilter_ipv4.h>
+#include <linux/slab.h>
+#include <net/snmp.h>
+#include <net/ip.h>
+#include <net/route.h>
+#include <net/protocol.h>
+#include <net/icmp.h>
+#include <net/tcp.h>
+#include <net/udp.h>
+#include <net/raw.h>
+#include <net/ping.h>
+#include <linux/skbuff.h>
+#include <net/sock.h>
+#include <linux/errno.h>
+#include <linux/timer.h>
+#include <linux/init.h>
+#include <linux/uaccess.h>
+#include <net/checksum.h>
+#include <net/xfrm.h>
+#include <net/inet_common.h>
+#include <net/ip_fib.h>
+#include <net/l3mdev.h>
+
+/*
+ * Build xmit assembly blocks
+ */
+
+struct icmp_bxm {
+ struct sk_buff *skb;
+ int offset;
+ int data_len;
+
+ struct {
+ struct icmphdr icmph;
+ __be32 times[3];
+ } data;
+ int head_len;
+ struct ip_options_data replyopts;
+};
+
+/* An array of errno for error messages from dest unreach. */
+/* RFC 1122: 3.2.2.1 States that NET_UNREACH, HOST_UNREACH and SR_FAILED MUST be considered 'transient errs'. */
+
+const struct icmp_err icmp_err_convert[] = {
+ {
+ .errno = ENETUNREACH, /* ICMP_NET_UNREACH */
+ .fatal = 0,
+ },
+ {
+ .errno = EHOSTUNREACH, /* ICMP_HOST_UNREACH */
+ .fatal = 0,
+ },
+ {
+ .errno = ENOPROTOOPT /* ICMP_PROT_UNREACH */,
+ .fatal = 1,
+ },
+ {
+ .errno = ECONNREFUSED, /* ICMP_PORT_UNREACH */
+ .fatal = 1,
+ },
+ {
+ .errno = EMSGSIZE, /* ICMP_FRAG_NEEDED */
+ .fatal = 0,
+ },
+ {
+ .errno = EOPNOTSUPP, /* ICMP_SR_FAILED */
+ .fatal = 0,
+ },
+ {
+ .errno = ENETUNREACH, /* ICMP_NET_UNKNOWN */
+ .fatal = 1,
+ },
+ {
+ .errno = EHOSTDOWN, /* ICMP_HOST_UNKNOWN */
+ .fatal = 1,
+ },
+ {
+ .errno = ENONET, /* ICMP_HOST_ISOLATED */
+ .fatal = 1,
+ },
+ {
+ .errno = ENETUNREACH, /* ICMP_NET_ANO */
+ .fatal = 1,
+ },
+ {
+ .errno = EHOSTUNREACH, /* ICMP_HOST_ANO */
+ .fatal = 1,
+ },
+ {
+ .errno = ENETUNREACH, /* ICMP_NET_UNR_TOS */
+ .fatal = 0,
+ },
+ {
+ .errno = EHOSTUNREACH, /* ICMP_HOST_UNR_TOS */
+ .fatal = 0,
+ },
+ {
+ .errno = EHOSTUNREACH, /* ICMP_PKT_FILTERED */
+ .fatal = 1,
+ },
+ {
+ .errno = EHOSTUNREACH, /* ICMP_PREC_VIOLATION */
+ .fatal = 1,
+ },
+ {
+ .errno = EHOSTUNREACH, /* ICMP_PREC_CUTOFF */
+ .fatal = 1,
+ },
+};
+EXPORT_SYMBOL(icmp_err_convert);
+
+/*
+ * ICMP control array. This specifies what to do with each ICMP.
+ */
+
+struct icmp_control {
+ bool (*handler)(struct sk_buff *skb);
+ short error; /* This ICMP is classed as an error message */
+};
+
+static const struct icmp_control icmp_pointers[NR_ICMP_TYPES+1];
+
+/*
+ * The ICMP socket(s). This is the most convenient way to flow control
+ * our ICMP output as well as maintain a clean interface throughout
+ * all layers. All Socketless IP sends will soon be gone.
+ *
+ * On SMP we have one ICMP socket per-cpu.
+ */
+static struct sock *icmp_sk(struct net *net)
+{
+ return this_cpu_read(*net->ipv4.icmp_sk);
+}
+
+/* Called with BH disabled */
+static inline struct sock *icmp_xmit_lock(struct net *net)
+{
+ struct sock *sk;
+
+ sk = icmp_sk(net);
+
+ if (unlikely(!spin_trylock(&sk->sk_lock.slock))) {
+ /* This can happen if the output path signals a
+ * dst_link_failure() for an outgoing ICMP packet.
+ */
+ return NULL;
+ }
+ return sk;
+}
+
+static inline void icmp_xmit_unlock(struct sock *sk)
+{
+ spin_unlock(&sk->sk_lock.slock);
+}
+
+int sysctl_icmp_msgs_per_sec __read_mostly = 1000;
+int sysctl_icmp_msgs_burst __read_mostly = 50;
+
+static struct {
+ spinlock_t lock;
+ u32 credit;
+ u32 stamp;
+} icmp_global = {
+ .lock = __SPIN_LOCK_UNLOCKED(icmp_global.lock),
+};
+
+/**
+ * icmp_global_allow - Are we allowed to send one more ICMP message ?
+ *
+ * Uses a token bucket to limit our ICMP messages to ~sysctl_icmp_msgs_per_sec.
+ * Returns false if we reached the limit and can not send another packet.
+ * Note: called with BH disabled
+ */
+bool icmp_global_allow(void)
+{
+ u32 credit, delta, incr = 0, now = (u32)jiffies;
+ bool rc = false;
+
+ /* Check if token bucket is empty and cannot be refilled
+ * without taking the spinlock. The READ_ONCE() are paired
+ * with the following WRITE_ONCE() in this same function.
+ */
+ if (!READ_ONCE(icmp_global.credit)) {
+ delta = min_t(u32, now - READ_ONCE(icmp_global.stamp), HZ);
+ if (delta < HZ / 50)
+ return false;
+ }
+
+ spin_lock(&icmp_global.lock);
+ delta = min_t(u32, now - icmp_global.stamp, HZ);
+ if (delta >= HZ / 50) {
+ incr = READ_ONCE(sysctl_icmp_msgs_per_sec) * delta / HZ;
+ if (incr)
+ WRITE_ONCE(icmp_global.stamp, now);
+ }
+ credit = min_t(u32, icmp_global.credit + incr,
+ READ_ONCE(sysctl_icmp_msgs_burst));
+ if (credit) {
+ /* We want to use a credit of one in average, but need to randomize
+ * it for security reasons.
+ */
+ credit = max_t(int, credit - prandom_u32_max(3), 0);
+ rc = true;
+ }
+ WRITE_ONCE(icmp_global.credit, credit);
+ spin_unlock(&icmp_global.lock);
+ return rc;
+}
+EXPORT_SYMBOL(icmp_global_allow);
+
+static bool icmpv4_mask_allow(struct net *net, int type, int code)
+{
+ if (type > NR_ICMP_TYPES)
+ return true;
+
+ /* Don't limit PMTU discovery. */
+ if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED)
+ return true;
+
+ /* Limit if icmp type is enabled in ratemask. */
+ if (!((1 << type) & READ_ONCE(net->ipv4.sysctl_icmp_ratemask)))
+ return true;
+
+ return false;
+}
+
+static bool icmpv4_global_allow(struct net *net, int type, int code)
+{
+ if (icmpv4_mask_allow(net, type, code))
+ return true;
+
+ if (icmp_global_allow())
+ return true;
+
+ return false;
+}
+
+/*
+ * Send an ICMP frame.
+ */
+
+static bool icmpv4_xrlim_allow(struct net *net, struct rtable *rt,
+ struct flowi4 *fl4, int type, int code)
+{
+ struct dst_entry *dst = &rt->dst;
+ struct inet_peer *peer;
+ bool rc = true;
+ int vif;
+
+ if (icmpv4_mask_allow(net, type, code))
+ goto out;
+
+ /* No rate limit on loopback */
+ if (dst->dev && (dst->dev->flags&IFF_LOOPBACK))
+ goto out;
+
+ vif = l3mdev_master_ifindex(dst->dev);
+ peer = inet_getpeer_v4(net->ipv4.peers, fl4->daddr, vif, 1);
+ rc = inet_peer_xrlim_allow(peer,
+ READ_ONCE(net->ipv4.sysctl_icmp_ratelimit));
+ if (peer)
+ inet_putpeer(peer);
+out:
+ return rc;
+}
+
+/*
+ * Maintain the counters used in the SNMP statistics for outgoing ICMP
+ */
+void icmp_out_count(struct net *net, unsigned char type)
+{
+ ICMPMSGOUT_INC_STATS(net, type);
+ ICMP_INC_STATS(net, ICMP_MIB_OUTMSGS);
+}
+
+/*
+ * Checksum each fragment, and on the first include the headers and final
+ * checksum.
+ */
+static int icmp_glue_bits(void *from, char *to, int offset, int len, int odd,
+ struct sk_buff *skb)
+{
+ struct icmp_bxm *icmp_param = (struct icmp_bxm *)from;
+ __wsum csum;
+
+ csum = skb_copy_and_csum_bits(icmp_param->skb,
+ icmp_param->offset + offset,
+ to, len);
+
+ skb->csum = csum_block_add(skb->csum, csum, odd);
+ if (icmp_pointers[icmp_param->data.icmph.type].error)
+ nf_ct_attach(skb, icmp_param->skb);
+ return 0;
+}
+
+static void icmp_push_reply(struct icmp_bxm *icmp_param,
+ struct flowi4 *fl4,
+ struct ipcm_cookie *ipc, struct rtable **rt)
+{
+ struct sock *sk;
+ struct sk_buff *skb;
+
+ sk = icmp_sk(dev_net((*rt)->dst.dev));
+ if (ip_append_data(sk, fl4, icmp_glue_bits, icmp_param,
+ icmp_param->data_len+icmp_param->head_len,
+ icmp_param->head_len,
+ ipc, rt, MSG_DONTWAIT) < 0) {
+ __ICMP_INC_STATS(sock_net(sk), ICMP_MIB_OUTERRORS);
+ ip_flush_pending_frames(sk);
+ } else if ((skb = skb_peek(&sk->sk_write_queue)) != NULL) {
+ struct icmphdr *icmph = icmp_hdr(skb);
+ __wsum csum;
+ struct sk_buff *skb1;
+
+ csum = csum_partial_copy_nocheck((void *)&icmp_param->data,
+ (char *)icmph,
+ icmp_param->head_len);
+ skb_queue_walk(&sk->sk_write_queue, skb1) {
+ csum = csum_add(csum, skb1->csum);
+ }
+ icmph->checksum = csum_fold(csum);
+ skb->ip_summed = CHECKSUM_NONE;
+ ip_push_pending_frames(sk, fl4);
+ }
+}
+
+/*
+ * Driving logic for building and sending ICMP messages.
+ */
+
+static void icmp_reply(struct icmp_bxm *icmp_param, struct sk_buff *skb)
+{
+ struct ipcm_cookie ipc;
+ struct rtable *rt = skb_rtable(skb);
+ struct net *net = dev_net(rt->dst.dev);
+ struct flowi4 fl4;
+ struct sock *sk;
+ struct inet_sock *inet;
+ __be32 daddr, saddr;
+ u32 mark = IP4_REPLY_MARK(net, skb->mark);
+ int type = icmp_param->data.icmph.type;
+ int code = icmp_param->data.icmph.code;
+
+ if (ip_options_echo(net, &icmp_param->replyopts.opt.opt, skb))
+ return;
+
+ /* Needed by both icmp_global_allow and icmp_xmit_lock */
+ local_bh_disable();
+
+ /* global icmp_msgs_per_sec */
+ if (!icmpv4_global_allow(net, type, code))
+ goto out_bh_enable;
+
+ sk = icmp_xmit_lock(net);
+ if (!sk)
+ goto out_bh_enable;
+ inet = inet_sk(sk);
+
+ icmp_param->data.icmph.checksum = 0;
+
+ ipcm_init(&ipc);
+ inet->tos = ip_hdr(skb)->tos;
+ ipc.sockc.mark = mark;
+ daddr = ipc.addr = ip_hdr(skb)->saddr;
+ saddr = fib_compute_spec_dst(skb);
+
+ if (icmp_param->replyopts.opt.opt.optlen) {
+ ipc.opt = &icmp_param->replyopts.opt;
+ if (ipc.opt->opt.srr)
+ daddr = icmp_param->replyopts.opt.opt.faddr;
+ }
+ memset(&fl4, 0, sizeof(fl4));
+ fl4.daddr = daddr;
+ fl4.saddr = saddr;
+ fl4.flowi4_mark = mark;
+ fl4.flowi4_uid = sock_net_uid(net, NULL);
+ fl4.flowi4_tos = RT_TOS(ip_hdr(skb)->tos);
+ fl4.flowi4_proto = IPPROTO_ICMP;
+ fl4.flowi4_oif = l3mdev_master_ifindex(skb->dev);
+ security_skb_classify_flow(skb, flowi4_to_flowi_common(&fl4));
+ rt = ip_route_output_key(net, &fl4);
+ if (IS_ERR(rt))
+ goto out_unlock;
+ if (icmpv4_xrlim_allow(net, rt, &fl4, type, code))
+ icmp_push_reply(icmp_param, &fl4, &ipc, &rt);
+ ip_rt_put(rt);
+out_unlock:
+ icmp_xmit_unlock(sk);
+out_bh_enable:
+ local_bh_enable();
+}
+
+/*
+ * The device used for looking up which routing table to use for sending an ICMP
+ * error is preferably the source whenever it is set, which should ensure the
+ * icmp error can be sent to the source host, else lookup using the routing
+ * table of the destination device, else use the main routing table (index 0).
+ */
+static struct net_device *icmp_get_route_lookup_dev(struct sk_buff *skb)
+{
+ struct net_device *route_lookup_dev = NULL;
+
+ if (skb->dev)
+ route_lookup_dev = skb->dev;
+ else if (skb_dst(skb))
+ route_lookup_dev = skb_dst(skb)->dev;
+ return route_lookup_dev;
+}
+
+static struct rtable *icmp_route_lookup(struct net *net,
+ struct flowi4 *fl4,
+ struct sk_buff *skb_in,
+ const struct iphdr *iph,
+ __be32 saddr, u8 tos, u32 mark,
+ int type, int code,
+ struct icmp_bxm *param)
+{
+ struct net_device *route_lookup_dev;
+ struct rtable *rt, *rt2;
+ struct flowi4 fl4_dec;
+ int err;
+
+ memset(fl4, 0, sizeof(*fl4));
+ fl4->daddr = (param->replyopts.opt.opt.srr ?
+ param->replyopts.opt.opt.faddr : iph->saddr);
+ fl4->saddr = saddr;
+ fl4->flowi4_mark = mark;
+ fl4->flowi4_uid = sock_net_uid(net, NULL);
+ fl4->flowi4_tos = RT_TOS(tos);
+ fl4->flowi4_proto = IPPROTO_ICMP;
+ fl4->fl4_icmp_type = type;
+ fl4->fl4_icmp_code = code;
+ route_lookup_dev = icmp_get_route_lookup_dev(skb_in);
+ fl4->flowi4_oif = l3mdev_master_ifindex(route_lookup_dev);
+
+ security_skb_classify_flow(skb_in, flowi4_to_flowi_common(fl4));
+ rt = ip_route_output_key_hash(net, fl4, skb_in);
+ if (IS_ERR(rt))
+ return rt;
+
+ /* No need to clone since we're just using its address. */
+ rt2 = rt;
+
+ rt = (struct rtable *) xfrm_lookup(net, &rt->dst,
+ flowi4_to_flowi(fl4), NULL, 0);
+ if (!IS_ERR(rt)) {
+ if (rt != rt2)
+ return rt;
+ } else if (PTR_ERR(rt) == -EPERM) {
+ rt = NULL;
+ } else
+ return rt;
+
+ err = xfrm_decode_session_reverse(skb_in, flowi4_to_flowi(&fl4_dec), AF_INET);
+ if (err)
+ goto relookup_failed;
+
+ if (inet_addr_type_dev_table(net, route_lookup_dev,
+ fl4_dec.saddr) == RTN_LOCAL) {
+ rt2 = __ip_route_output_key(net, &fl4_dec);
+ if (IS_ERR(rt2))
+ err = PTR_ERR(rt2);
+ } else {
+ struct flowi4 fl4_2 = {};
+ unsigned long orefdst;
+
+ fl4_2.daddr = fl4_dec.saddr;
+ rt2 = ip_route_output_key(net, &fl4_2);
+ if (IS_ERR(rt2)) {
+ err = PTR_ERR(rt2);
+ goto relookup_failed;
+ }
+ /* Ugh! */
+ orefdst = skb_in->_skb_refdst; /* save old refdst */
+ skb_dst_set(skb_in, NULL);
+ err = ip_route_input(skb_in, fl4_dec.daddr, fl4_dec.saddr,
+ RT_TOS(tos), rt2->dst.dev);
+
+ dst_release(&rt2->dst);
+ rt2 = skb_rtable(skb_in);
+ skb_in->_skb_refdst = orefdst; /* restore old refdst */
+ }
+
+ if (err)
+ goto relookup_failed;
+
+ rt2 = (struct rtable *) xfrm_lookup(net, &rt2->dst,
+ flowi4_to_flowi(&fl4_dec), NULL,
+ XFRM_LOOKUP_ICMP);
+ if (!IS_ERR(rt2)) {
+ dst_release(&rt->dst);
+ memcpy(fl4, &fl4_dec, sizeof(*fl4));
+ rt = rt2;
+ } else if (PTR_ERR(rt2) == -EPERM) {
+ if (rt)
+ dst_release(&rt->dst);
+ return rt2;
+ } else {
+ err = PTR_ERR(rt2);
+ goto relookup_failed;
+ }
+ return rt;
+
+relookup_failed:
+ if (rt)
+ return rt;
+ return ERR_PTR(err);
+}
+
+/*
+ * Send an ICMP message in response to a situation
+ *
+ * RFC 1122: 3.2.2 MUST send at least the IP header and 8 bytes of header.
+ * MAY send more (we do).
+ * MUST NOT change this header information.
+ * MUST NOT reply to a multicast/broadcast IP address.
+ * MUST NOT reply to a multicast/broadcast MAC address.
+ * MUST reply to only the first fragment.
+ */
+
+void __icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info,
+ const struct ip_options *opt)
+{
+ struct iphdr *iph;
+ int room;
+ struct icmp_bxm icmp_param;
+ struct rtable *rt = skb_rtable(skb_in);
+ struct ipcm_cookie ipc;
+ struct flowi4 fl4;
+ __be32 saddr;
+ u8 tos;
+ u32 mark;
+ struct net *net;
+ struct sock *sk;
+
+ if (!rt)
+ goto out;
+
+ if (rt->dst.dev)
+ net = dev_net(rt->dst.dev);
+ else if (skb_in->dev)
+ net = dev_net(skb_in->dev);
+ else
+ goto out;
+
+ /*
+ * Find the original header. It is expected to be valid, of course.
+ * Check this, icmp_send is called from the most obscure devices
+ * sometimes.
+ */
+ iph = ip_hdr(skb_in);
+
+ if ((u8 *)iph < skb_in->head ||
+ (skb_network_header(skb_in) + sizeof(*iph)) >
+ skb_tail_pointer(skb_in))
+ goto out;
+
+ /*
+ * No replies to physical multicast/broadcast
+ */
+ if (skb_in->pkt_type != PACKET_HOST)
+ goto out;
+
+ /*
+ * Now check at the protocol level
+ */
+ if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST))
+ goto out;
+
+ /*
+ * Only reply to fragment 0. We byte re-order the constant
+ * mask for efficiency.
+ */
+ if (iph->frag_off & htons(IP_OFFSET))
+ goto out;
+
+ /*
+ * If we send an ICMP error to an ICMP error a mess would result..
+ */
+ if (icmp_pointers[type].error) {
+ /*
+ * We are an error, check if we are replying to an
+ * ICMP error
+ */
+ if (iph->protocol == IPPROTO_ICMP) {
+ u8 _inner_type, *itp;
+
+ itp = skb_header_pointer(skb_in,
+ skb_network_header(skb_in) +
+ (iph->ihl << 2) +
+ offsetof(struct icmphdr,
+ type) -
+ skb_in->data,
+ sizeof(_inner_type),
+ &_inner_type);
+ if (!itp)
+ goto out;
+
+ /*
+ * Assume any unknown ICMP type is an error. This
+ * isn't specified by the RFC, but think about it..
+ */
+ if (*itp > NR_ICMP_TYPES ||
+ icmp_pointers[*itp].error)
+ goto out;
+ }
+ }
+
+ /* Needed by both icmp_global_allow and icmp_xmit_lock */
+ local_bh_disable();
+
+ /* Check global sysctl_icmp_msgs_per_sec ratelimit, unless
+ * incoming dev is loopback. If outgoing dev change to not be
+ * loopback, then peer ratelimit still work (in icmpv4_xrlim_allow)
+ */
+ if (!(skb_in->dev && (skb_in->dev->flags&IFF_LOOPBACK)) &&
+ !icmpv4_global_allow(net, type, code))
+ goto out_bh_enable;
+
+ sk = icmp_xmit_lock(net);
+ if (!sk)
+ goto out_bh_enable;
+
+ /*
+ * Construct source address and options.
+ */
+
+ saddr = iph->daddr;
+ if (!(rt->rt_flags & RTCF_LOCAL)) {
+ struct net_device *dev = NULL;
+
+ rcu_read_lock();
+ if (rt_is_input_route(rt) &&
+ net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr)
+ dev = dev_get_by_index_rcu(net, inet_iif(skb_in));
+
+ if (dev)
+ saddr = inet_select_addr(dev, iph->saddr,
+ RT_SCOPE_LINK);
+ else
+ saddr = 0;
+ rcu_read_unlock();
+ }
+
+ tos = icmp_pointers[type].error ? (RT_TOS(iph->tos) |
+ IPTOS_PREC_INTERNETCONTROL) :
+ iph->tos;
+ mark = IP4_REPLY_MARK(net, skb_in->mark);
+
+ if (__ip_options_echo(net, &icmp_param.replyopts.opt.opt, skb_in, opt))
+ goto out_unlock;
+
+
+ /*
+ * Prepare data for ICMP header.
+ */
+
+ icmp_param.data.icmph.type = type;
+ icmp_param.data.icmph.code = code;
+ icmp_param.data.icmph.un.gateway = info;
+ icmp_param.data.icmph.checksum = 0;
+ icmp_param.skb = skb_in;
+ icmp_param.offset = skb_network_offset(skb_in);
+ inet_sk(sk)->tos = tos;
+ ipcm_init(&ipc);
+ ipc.addr = iph->saddr;
+ ipc.opt = &icmp_param.replyopts.opt;
+ ipc.sockc.mark = mark;
+
+ rt = icmp_route_lookup(net, &fl4, skb_in, iph, saddr, tos, mark,
+ type, code, &icmp_param);
+ if (IS_ERR(rt))
+ goto out_unlock;
+
+ /* peer icmp_ratelimit */
+ if (!icmpv4_xrlim_allow(net, rt, &fl4, type, code))
+ goto ende;
+
+ /* RFC says return as much as we can without exceeding 576 bytes. */
+
+ room = dst_mtu(&rt->dst);
+ if (room > 576)
+ room = 576;
+ room -= sizeof(struct iphdr) + icmp_param.replyopts.opt.opt.optlen;
+ room -= sizeof(struct icmphdr);
+ /* Guard against tiny mtu. We need to include at least one
+ * IP network header for this message to make any sense.
+ */
+ if (room <= (int)sizeof(struct iphdr))
+ goto ende;
+
+ icmp_param.data_len = skb_in->len - icmp_param.offset;
+ if (icmp_param.data_len > room)
+ icmp_param.data_len = room;
+ icmp_param.head_len = sizeof(struct icmphdr);
+
+ /* if we don't have a source address at this point, fall back to the
+ * dummy address instead of sending out a packet with a source address
+ * of 0.0.0.0
+ */
+ if (!fl4.saddr)
+ fl4.saddr = htonl(INADDR_DUMMY);
+
+ icmp_push_reply(&icmp_param, &fl4, &ipc, &rt);
+ende:
+ ip_rt_put(rt);
+out_unlock:
+ icmp_xmit_unlock(sk);
+out_bh_enable:
+ local_bh_enable();
+out:;
+}
+EXPORT_SYMBOL(__icmp_send);
+
+#if IS_ENABLED(CONFIG_NF_NAT)
+#include <net/netfilter/nf_conntrack.h>
+void icmp_ndo_send(struct sk_buff *skb_in, int type, int code, __be32 info)
+{
+ struct sk_buff *cloned_skb = NULL;
+ struct ip_options opts = { 0 };
+ enum ip_conntrack_info ctinfo;
+ struct nf_conn *ct;
+ __be32 orig_ip;
+
+ ct = nf_ct_get(skb_in, &ctinfo);
+ if (!ct || !(ct->status & IPS_SRC_NAT)) {
+ __icmp_send(skb_in, type, code, info, &opts);
+ return;
+ }
+
+ if (skb_shared(skb_in))
+ skb_in = cloned_skb = skb_clone(skb_in, GFP_ATOMIC);
+
+ if (unlikely(!skb_in || skb_network_header(skb_in) < skb_in->head ||
+ (skb_network_header(skb_in) + sizeof(struct iphdr)) >
+ skb_tail_pointer(skb_in) || skb_ensure_writable(skb_in,
+ skb_network_offset(skb_in) + sizeof(struct iphdr))))
+ goto out;
+
+ orig_ip = ip_hdr(skb_in)->saddr;
+ ip_hdr(skb_in)->saddr = ct->tuplehash[0].tuple.src.u3.ip;
+ __icmp_send(skb_in, type, code, info, &opts);
+ ip_hdr(skb_in)->saddr = orig_ip;
+out:
+ consume_skb(cloned_skb);
+}
+EXPORT_SYMBOL(icmp_ndo_send);
+#endif
+
+static void icmp_socket_deliver(struct sk_buff *skb, u32 info)
+{
+ const struct iphdr *iph = (const struct iphdr *)skb->data;
+ const struct net_protocol *ipprot;
+ int protocol = iph->protocol;
+
+ /* Checkin full IP header plus 8 bytes of protocol to
+ * avoid additional coding at protocol handlers.
+ */
+ if (!pskb_may_pull(skb, iph->ihl * 4 + 8)) {
+ __ICMP_INC_STATS(dev_net(skb->dev), ICMP_MIB_INERRORS);
+ return;
+ }
+
+ raw_icmp_error(skb, protocol, info);
+
+ ipprot = rcu_dereference(inet_protos[protocol]);
+ if (ipprot && ipprot->err_handler)
+ ipprot->err_handler(skb, info);
+}
+
+static bool icmp_tag_validation(int proto)
+{
+ bool ok;
+
+ rcu_read_lock();
+ ok = rcu_dereference(inet_protos[proto])->icmp_strict_tag_validation;
+ rcu_read_unlock();
+ return ok;
+}
+
+/*
+ * Handle ICMP_DEST_UNREACH, ICMP_TIME_EXCEEDED, ICMP_QUENCH, and
+ * ICMP_PARAMETERPROB.
+ */
+
+static bool icmp_unreach(struct sk_buff *skb)
+{
+ const struct iphdr *iph;
+ struct icmphdr *icmph;
+ struct net *net;
+ u32 info = 0;
+
+ net = dev_net(skb_dst(skb)->dev);
+
+ /*
+ * Incomplete header ?
+ * Only checks for the IP header, there should be an
+ * additional check for longer headers in upper levels.
+ */
+
+ if (!pskb_may_pull(skb, sizeof(struct iphdr)))
+ goto out_err;
+
+ icmph = icmp_hdr(skb);
+ iph = (const struct iphdr *)skb->data;
+
+ if (iph->ihl < 5) /* Mangled header, drop. */
+ goto out_err;
+
+ switch (icmph->type) {
+ case ICMP_DEST_UNREACH:
+ switch (icmph->code & 15) {
+ case ICMP_NET_UNREACH:
+ case ICMP_HOST_UNREACH:
+ case ICMP_PROT_UNREACH:
+ case ICMP_PORT_UNREACH:
+ break;
+ case ICMP_FRAG_NEEDED:
+ /* for documentation of the ip_no_pmtu_disc
+ * values please see
+ * Documentation/networking/ip-sysctl.rst
+ */
+ switch (READ_ONCE(net->ipv4.sysctl_ip_no_pmtu_disc)) {
+ default:
+ net_dbg_ratelimited("%pI4: fragmentation needed and DF set\n",
+ &iph->daddr);
+ break;
+ case 2:
+ goto out;
+ case 3:
+ if (!icmp_tag_validation(iph->protocol))
+ goto out;
+ fallthrough;
+ case 0:
+ info = ntohs(icmph->un.frag.mtu);
+ }
+ break;
+ case ICMP_SR_FAILED:
+ net_dbg_ratelimited("%pI4: Source Route Failed\n",
+ &iph->daddr);
+ break;
+ default:
+ break;
+ }
+ if (icmph->code > NR_ICMP_UNREACH)
+ goto out;
+ break;
+ case ICMP_PARAMETERPROB:
+ info = ntohl(icmph->un.gateway) >> 24;
+ break;
+ case ICMP_TIME_EXCEEDED:
+ __ICMP_INC_STATS(net, ICMP_MIB_INTIMEEXCDS);
+ if (icmph->code == ICMP_EXC_FRAGTIME)
+ goto out;
+ break;
+ }
+
+ /*
+ * Throw it at our lower layers
+ *
+ * RFC 1122: 3.2.2 MUST extract the protocol ID from the passed
+ * header.
+ * RFC 1122: 3.2.2.1 MUST pass ICMP unreach messages to the
+ * transport layer.
+ * RFC 1122: 3.2.2.2 MUST pass ICMP time expired messages to
+ * transport layer.
+ */
+
+ /*
+ * Check the other end isn't violating RFC 1122. Some routers send
+ * bogus responses to broadcast frames. If you see this message
+ * first check your netmask matches at both ends, if it does then
+ * get the other vendor to fix their kit.
+ */
+
+ if (!net->ipv4.sysctl_icmp_ignore_bogus_error_responses &&
+ inet_addr_type_dev_table(net, skb->dev, iph->daddr) == RTN_BROADCAST) {
+ net_warn_ratelimited("%pI4 sent an invalid ICMP type %u, code %u error to a broadcast: %pI4 on %s\n",
+ &ip_hdr(skb)->saddr,
+ icmph->type, icmph->code,
+ &iph->daddr, skb->dev->name);
+ goto out;
+ }
+
+ icmp_socket_deliver(skb, info);
+
+out:
+ return true;
+out_err:
+ __ICMP_INC_STATS(net, ICMP_MIB_INERRORS);
+ return false;
+}
+
+
+/*
+ * Handle ICMP_REDIRECT.
+ */
+
+static bool icmp_redirect(struct sk_buff *skb)
+{
+ if (skb->len < sizeof(struct iphdr)) {
+ __ICMP_INC_STATS(dev_net(skb->dev), ICMP_MIB_INERRORS);
+ return false;
+ }
+
+ if (!pskb_may_pull(skb, sizeof(struct iphdr))) {
+ /* there aught to be a stat */
+ return false;
+ }
+
+ icmp_socket_deliver(skb, ntohl(icmp_hdr(skb)->un.gateway));
+ return true;
+}
+
+/*
+ * Handle ICMP_ECHO ("ping") requests.
+ *
+ * RFC 1122: 3.2.2.6 MUST have an echo server that answers ICMP echo
+ * requests.
+ * RFC 1122: 3.2.2.6 Data received in the ICMP_ECHO request MUST be
+ * included in the reply.
+ * RFC 1812: 4.3.3.6 SHOULD have a config option for silently ignoring
+ * echo requests, MUST have default=NOT.
+ * See also WRT handling of options once they are done and working.
+ */
+
+static bool icmp_echo(struct sk_buff *skb)
+{
+ struct net *net;
+
+ net = dev_net(skb_dst(skb)->dev);
+ if (!net->ipv4.sysctl_icmp_echo_ignore_all) {
+ struct icmp_bxm icmp_param;
+
+ icmp_param.data.icmph = *icmp_hdr(skb);
+ icmp_param.data.icmph.type = ICMP_ECHOREPLY;
+ icmp_param.skb = skb;
+ icmp_param.offset = 0;
+ icmp_param.data_len = skb->len;
+ icmp_param.head_len = sizeof(struct icmphdr);
+ icmp_reply(&icmp_param, skb);
+ }
+ /* should there be an ICMP stat for ignored echos? */
+ return true;
+}
+
+/*
+ * Handle ICMP Timestamp requests.
+ * RFC 1122: 3.2.2.8 MAY implement ICMP timestamp requests.
+ * SHOULD be in the kernel for minimum random latency.
+ * MUST be accurate to a few minutes.
+ * MUST be updated at least at 15Hz.
+ */
+static bool icmp_timestamp(struct sk_buff *skb)
+{
+ struct icmp_bxm icmp_param;
+ /*
+ * Too short.
+ */
+ if (skb->len < 4)
+ goto out_err;
+
+ /*
+ * Fill in the current time as ms since midnight UT:
+ */
+ icmp_param.data.times[1] = inet_current_timestamp();
+ icmp_param.data.times[2] = icmp_param.data.times[1];
+
+ BUG_ON(skb_copy_bits(skb, 0, &icmp_param.data.times[0], 4));
+
+ icmp_param.data.icmph = *icmp_hdr(skb);
+ icmp_param.data.icmph.type = ICMP_TIMESTAMPREPLY;
+ icmp_param.data.icmph.code = 0;
+ icmp_param.skb = skb;
+ icmp_param.offset = 0;
+ icmp_param.data_len = 0;
+ icmp_param.head_len = sizeof(struct icmphdr) + 12;
+ icmp_reply(&icmp_param, skb);
+ return true;
+
+out_err:
+ __ICMP_INC_STATS(dev_net(skb_dst(skb)->dev), ICMP_MIB_INERRORS);
+ return false;
+}
+
+static bool icmp_discard(struct sk_buff *skb)
+{
+ /* pretend it was a success */
+ return true;
+}
+
+/*
+ * Deal with incoming ICMP packets.
+ */
+int icmp_rcv(struct sk_buff *skb)
+{
+ struct icmphdr *icmph;
+ struct rtable *rt = skb_rtable(skb);
+ struct net *net = dev_net(rt->dst.dev);
+ bool success;
+
+ if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
+ struct sec_path *sp = skb_sec_path(skb);
+ int nh;
+
+ if (!(sp && sp->xvec[sp->len - 1]->props.flags &
+ XFRM_STATE_ICMP))
+ goto drop;
+
+ if (!pskb_may_pull(skb, sizeof(*icmph) + sizeof(struct iphdr)))
+ goto drop;
+
+ nh = skb_network_offset(skb);
+ skb_set_network_header(skb, sizeof(*icmph));
+
+ if (!xfrm4_policy_check_reverse(NULL, XFRM_POLICY_IN, skb))
+ goto drop;
+
+ skb_set_network_header(skb, nh);
+ }
+
+ __ICMP_INC_STATS(net, ICMP_MIB_INMSGS);
+
+ if (skb_checksum_simple_validate(skb))
+ goto csum_error;
+
+ if (!pskb_pull(skb, sizeof(*icmph)))
+ goto error;
+
+ icmph = icmp_hdr(skb);
+
+ ICMPMSGIN_INC_STATS(net, icmph->type);
+ /*
+ * 18 is the highest 'known' ICMP type. Anything else is a mystery
+ *
+ * RFC 1122: 3.2.2 Unknown ICMP messages types MUST be silently
+ * discarded.
+ */
+ if (icmph->type > NR_ICMP_TYPES)
+ goto error;
+
+
+ /*
+ * Parse the ICMP message
+ */
+
+ if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) {
+ /*
+ * RFC 1122: 3.2.2.6 An ICMP_ECHO to broadcast MAY be
+ * silently ignored (we let user decide with a sysctl).
+ * RFC 1122: 3.2.2.8 An ICMP_TIMESTAMP MAY be silently
+ * discarded if to broadcast/multicast.
+ */
+ if ((icmph->type == ICMP_ECHO ||
+ icmph->type == ICMP_TIMESTAMP) &&
+ net->ipv4.sysctl_icmp_echo_ignore_broadcasts) {
+ goto error;
+ }
+ if (icmph->type != ICMP_ECHO &&
+ icmph->type != ICMP_TIMESTAMP &&
+ icmph->type != ICMP_ADDRESS &&
+ icmph->type != ICMP_ADDRESSREPLY) {
+ goto error;
+ }
+ }
+
+ success = icmp_pointers[icmph->type].handler(skb);
+
+ if (success) {
+ consume_skb(skb);
+ return NET_RX_SUCCESS;
+ }
+
+drop:
+ kfree_skb(skb);
+ return NET_RX_DROP;
+csum_error:
+ __ICMP_INC_STATS(net, ICMP_MIB_CSUMERRORS);
+error:
+ __ICMP_INC_STATS(net, ICMP_MIB_INERRORS);
+ goto drop;
+}
+
+static bool ip_icmp_error_rfc4884_validate(const struct sk_buff *skb, int off)
+{
+ struct icmp_extobj_hdr *objh, _objh;
+ struct icmp_ext_hdr *exth, _exth;
+ u16 olen;
+
+ exth = skb_header_pointer(skb, off, sizeof(_exth), &_exth);
+ if (!exth)
+ return false;
+ if (exth->version != 2)
+ return true;
+
+ if (exth->checksum &&
+ csum_fold(skb_checksum(skb, off, skb->len - off, 0)))
+ return false;
+
+ off += sizeof(_exth);
+ while (off < skb->len) {
+ objh = skb_header_pointer(skb, off, sizeof(_objh), &_objh);
+ if (!objh)
+ return false;
+
+ olen = ntohs(objh->length);
+ if (olen < sizeof(_objh))
+ return false;
+
+ off += olen;
+ if (off > skb->len)
+ return false;
+ }
+
+ return true;
+}
+
+void ip_icmp_error_rfc4884(const struct sk_buff *skb,
+ struct sock_ee_data_rfc4884 *out,
+ int thlen, int off)
+{
+ int hlen;
+
+ /* original datagram headers: end of icmph to payload (skb->data) */
+ hlen = -skb_transport_offset(skb) - thlen;
+
+ /* per rfc 4884: minimal datagram length of 128 bytes */
+ if (off < 128 || off < hlen)
+ return;
+
+ /* kernel has stripped headers: return payload offset in bytes */
+ off -= hlen;
+ if (off + sizeof(struct icmp_ext_hdr) > skb->len)
+ return;
+
+ out->len = off;
+
+ if (!ip_icmp_error_rfc4884_validate(skb, off))
+ out->flags |= SO_EE_RFC4884_FLAG_INVALID;
+}
+EXPORT_SYMBOL_GPL(ip_icmp_error_rfc4884);
+
+int icmp_err(struct sk_buff *skb, u32 info)
+{
+ struct iphdr *iph = (struct iphdr *)skb->data;
+ int offset = iph->ihl<<2;
+ struct icmphdr *icmph = (struct icmphdr *)(skb->data + offset);
+ int type = icmp_hdr(skb)->type;
+ int code = icmp_hdr(skb)->code;
+ struct net *net = dev_net(skb->dev);
+
+ /*
+ * Use ping_err to handle all icmp errors except those
+ * triggered by ICMP_ECHOREPLY which sent from kernel.
+ */
+ if (icmph->type != ICMP_ECHOREPLY) {
+ ping_err(skb, offset, info);
+ return 0;
+ }
+
+ if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED)
+ ipv4_update_pmtu(skb, net, info, 0, IPPROTO_ICMP);
+ else if (type == ICMP_REDIRECT)
+ ipv4_redirect(skb, net, 0, IPPROTO_ICMP);
+
+ return 0;
+}
+
+/*
+ * This table is the definition of how we handle ICMP.
+ */
+static const struct icmp_control icmp_pointers[NR_ICMP_TYPES + 1] = {
+ [ICMP_ECHOREPLY] = {
+ .handler = ping_rcv,
+ },
+ [1] = {
+ .handler = icmp_discard,
+ .error = 1,
+ },
+ [2] = {
+ .handler = icmp_discard,
+ .error = 1,
+ },
+ [ICMP_DEST_UNREACH] = {
+ .handler = icmp_unreach,
+ .error = 1,
+ },
+ [ICMP_SOURCE_QUENCH] = {
+ .handler = icmp_unreach,
+ .error = 1,
+ },
+ [ICMP_REDIRECT] = {
+ .handler = icmp_redirect,
+ .error = 1,
+ },
+ [6] = {
+ .handler = icmp_discard,
+ .error = 1,
+ },
+ [7] = {
+ .handler = icmp_discard,
+ .error = 1,
+ },
+ [ICMP_ECHO] = {
+ .handler = icmp_echo,
+ },
+ [9] = {
+ .handler = icmp_discard,
+ .error = 1,
+ },
+ [10] = {
+ .handler = icmp_discard,
+ .error = 1,
+ },
+ [ICMP_TIME_EXCEEDED] = {
+ .handler = icmp_unreach,
+ .error = 1,
+ },
+ [ICMP_PARAMETERPROB] = {
+ .handler = icmp_unreach,
+ .error = 1,
+ },
+ [ICMP_TIMESTAMP] = {
+ .handler = icmp_timestamp,
+ },
+ [ICMP_TIMESTAMPREPLY] = {
+ .handler = icmp_discard,
+ },
+ [ICMP_INFO_REQUEST] = {
+ .handler = icmp_discard,
+ },
+ [ICMP_INFO_REPLY] = {
+ .handler = icmp_discard,
+ },
+ [ICMP_ADDRESS] = {
+ .handler = icmp_discard,
+ },
+ [ICMP_ADDRESSREPLY] = {
+ .handler = icmp_discard,
+ },
+};
+
+static void __net_exit icmp_sk_exit(struct net *net)
+{
+ int i;
+
+ for_each_possible_cpu(i)
+ inet_ctl_sock_destroy(*per_cpu_ptr(net->ipv4.icmp_sk, i));
+ free_percpu(net->ipv4.icmp_sk);
+ net->ipv4.icmp_sk = NULL;
+}
+
+static int __net_init icmp_sk_init(struct net *net)
+{
+ int i, err;
+
+ net->ipv4.icmp_sk = alloc_percpu(struct sock *);
+ if (!net->ipv4.icmp_sk)
+ return -ENOMEM;
+
+ for_each_possible_cpu(i) {
+ struct sock *sk;
+
+ err = inet_ctl_sock_create(&sk, PF_INET,
+ SOCK_RAW, IPPROTO_ICMP, net);
+ if (err < 0)
+ goto fail;
+
+ *per_cpu_ptr(net->ipv4.icmp_sk, i) = sk;
+
+ /* Enough space for 2 64K ICMP packets, including
+ * sk_buff/skb_shared_info struct overhead.
+ */
+ sk->sk_sndbuf = 2 * SKB_TRUESIZE(64 * 1024);
+
+ /*
+ * Speedup sock_wfree()
+ */
+ sock_set_flag(sk, SOCK_USE_WRITE_QUEUE);
+ inet_sk(sk)->pmtudisc = IP_PMTUDISC_DONT;
+ }
+
+ /* Control parameters for ECHO replies. */
+ net->ipv4.sysctl_icmp_echo_ignore_all = 0;
+ net->ipv4.sysctl_icmp_echo_ignore_broadcasts = 1;
+
+ /* Control parameter - ignore bogus broadcast responses? */
+ net->ipv4.sysctl_icmp_ignore_bogus_error_responses = 1;
+
+ /*
+ * Configurable global rate limit.
+ *
+ * ratelimit defines tokens/packet consumed for dst->rate_token
+ * bucket ratemask defines which icmp types are ratelimited by
+ * setting it's bit position.
+ *
+ * default:
+ * dest unreachable (3), source quench (4),
+ * time exceeded (11), parameter problem (12)
+ */
+
+ net->ipv4.sysctl_icmp_ratelimit = 1 * HZ;
+ net->ipv4.sysctl_icmp_ratemask = 0x1818;
+ net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr = 0;
+
+ return 0;
+
+fail:
+ icmp_sk_exit(net);
+ return err;
+}
+
+static struct pernet_operations __net_initdata icmp_sk_ops = {
+ .init = icmp_sk_init,
+ .exit = icmp_sk_exit,
+};
+
+int __init icmp_init(void)
+{
+ return register_pernet_subsys(&icmp_sk_ops);
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-22 18:01:25 +0000