From ace9429bb58fd418f0c81d4c2835699bddf6bde6 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Thu, 11 Apr 2024 10:27:49 +0200 Subject: Adding upstream version 6.6.15. Signed-off-by: Daniel Baumann --- net/ipv4/icmp.c | 1510 +++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 1510 insertions(+) create mode 100644 net/ipv4/icmp.c (limited to 'net/ipv4/icmp.c') diff --git a/net/ipv4/icmp.c b/net/ipv4/icmp.c new file mode 100644 index 0000000000..b8607763d1 --- /dev/null +++ b/net/ipv4/icmp.c @@ -0,0 +1,1510 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * NET3: Implementation of the ICMP protocol layer. + * + * Alan Cox, + * + * 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 +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +/* + * 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 { + enum skb_drop_reason (*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]; + +static DEFINE_PER_CPU(struct sock *, ipv4_icmp_sk); + +/* Called with BH disabled */ +static inline struct sock *icmp_xmit_lock(struct net *net) +{ + struct sock *sk; + + sk = this_cpu_read(ipv4_icmp_sk); + + 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; + } + sock_net_set(sk, net); + return sk; +} + +static inline void icmp_xmit_unlock(struct sock *sk) +{ + sock_net_set(sk, &init_net); + 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 - get_random_u32_below(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; + + __ICMP_INC_STATS(net, ICMP_MIB_RATELIMITGLOBAL); + 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: + if (!rc) + __ICMP_INC_STATS(net, ICMP_MIB_RATELIMITHOST); + 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 = 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 sock *sk, + struct icmp_bxm *icmp_param, + struct flowi4 *fl4, + struct ipcm_cookie *ipc, struct rtable **rt) +{ + struct sk_buff *skb; + + 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(sk, 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) && + READ_ONCE(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(sk, &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 +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 enum skb_drop_reason icmp_unreach(struct sk_buff *skb) +{ + enum skb_drop_reason reason = SKB_NOT_DROPPED_YET; + 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. */ + reason = SKB_DROP_REASON_IP_INHDR; + 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 (!READ_ONCE(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 reason; +out_err: + __ICMP_INC_STATS(net, ICMP_MIB_INERRORS); + return reason ?: SKB_DROP_REASON_NOT_SPECIFIED; +} + + +/* + * Handle ICMP_REDIRECT. + */ + +static enum skb_drop_reason icmp_redirect(struct sk_buff *skb) +{ + if (skb->len < sizeof(struct iphdr)) { + __ICMP_INC_STATS(dev_net(skb->dev), ICMP_MIB_INERRORS); + return SKB_DROP_REASON_PKT_TOO_SMALL; + } + + if (!pskb_may_pull(skb, sizeof(struct iphdr))) { + /* there aught to be a stat */ + return SKB_DROP_REASON_NOMEM; + } + + icmp_socket_deliver(skb, ntohl(icmp_hdr(skb)->un.gateway)); + return SKB_NOT_DROPPED_YET; +} + +/* + * Handle ICMP_ECHO ("ping") and ICMP_EXT_ECHO ("PROBE") 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. + * RFC 8335: 8 MUST have a config option to enable/disable ICMP + * Extended Echo Functionality, MUST be disabled by default + * See also WRT handling of options once they are done and working. + */ + +static enum skb_drop_reason icmp_echo(struct sk_buff *skb) +{ + struct icmp_bxm icmp_param; + struct net *net; + + net = dev_net(skb_dst(skb)->dev); + /* should there be an ICMP stat for ignored echos? */ + if (READ_ONCE(net->ipv4.sysctl_icmp_echo_ignore_all)) + return SKB_NOT_DROPPED_YET; + + icmp_param.data.icmph = *icmp_hdr(skb); + icmp_param.skb = skb; + icmp_param.offset = 0; + icmp_param.data_len = skb->len; + icmp_param.head_len = sizeof(struct icmphdr); + + if (icmp_param.data.icmph.type == ICMP_ECHO) + icmp_param.data.icmph.type = ICMP_ECHOREPLY; + else if (!icmp_build_probe(skb, &icmp_param.data.icmph)) + return SKB_NOT_DROPPED_YET; + + icmp_reply(&icmp_param, skb); + return SKB_NOT_DROPPED_YET; +} + +/* Helper for icmp_echo and icmpv6_echo_reply. + * Searches for net_device that matches PROBE interface identifier + * and builds PROBE reply message in icmphdr. + * + * Returns false if PROBE responses are disabled via sysctl + */ + +bool icmp_build_probe(struct sk_buff *skb, struct icmphdr *icmphdr) +{ + struct icmp_ext_hdr *ext_hdr, _ext_hdr; + struct icmp_ext_echo_iio *iio, _iio; + struct net *net = dev_net(skb->dev); + struct net_device *dev; + char buff[IFNAMSIZ]; + u16 ident_len; + u8 status; + + if (!READ_ONCE(net->ipv4.sysctl_icmp_echo_enable_probe)) + return false; + + /* We currently only support probing interfaces on the proxy node + * Check to ensure L-bit is set + */ + if (!(ntohs(icmphdr->un.echo.sequence) & 1)) + return false; + /* Clear status bits in reply message */ + icmphdr->un.echo.sequence &= htons(0xFF00); + if (icmphdr->type == ICMP_EXT_ECHO) + icmphdr->type = ICMP_EXT_ECHOREPLY; + else + icmphdr->type = ICMPV6_EXT_ECHO_REPLY; + ext_hdr = skb_header_pointer(skb, 0, sizeof(_ext_hdr), &_ext_hdr); + /* Size of iio is class_type dependent. + * Only check header here and assign length based on ctype in the switch statement + */ + iio = skb_header_pointer(skb, sizeof(_ext_hdr), sizeof(iio->extobj_hdr), &_iio); + if (!ext_hdr || !iio) + goto send_mal_query; + if (ntohs(iio->extobj_hdr.length) <= sizeof(iio->extobj_hdr) || + ntohs(iio->extobj_hdr.length) > sizeof(_iio)) + goto send_mal_query; + ident_len = ntohs(iio->extobj_hdr.length) - sizeof(iio->extobj_hdr); + iio = skb_header_pointer(skb, sizeof(_ext_hdr), + sizeof(iio->extobj_hdr) + ident_len, &_iio); + if (!iio) + goto send_mal_query; + + status = 0; + dev = NULL; + switch (iio->extobj_hdr.class_type) { + case ICMP_EXT_ECHO_CTYPE_NAME: + if (ident_len >= IFNAMSIZ) + goto send_mal_query; + memset(buff, 0, sizeof(buff)); + memcpy(buff, &iio->ident.name, ident_len); + dev = dev_get_by_name(net, buff); + break; + case ICMP_EXT_ECHO_CTYPE_INDEX: + if (ident_len != sizeof(iio->ident.ifindex)) + goto send_mal_query; + dev = dev_get_by_index(net, ntohl(iio->ident.ifindex)); + break; + case ICMP_EXT_ECHO_CTYPE_ADDR: + if (ident_len < sizeof(iio->ident.addr.ctype3_hdr) || + ident_len != sizeof(iio->ident.addr.ctype3_hdr) + + iio->ident.addr.ctype3_hdr.addrlen) + goto send_mal_query; + switch (ntohs(iio->ident.addr.ctype3_hdr.afi)) { + case ICMP_AFI_IP: + if (iio->ident.addr.ctype3_hdr.addrlen != sizeof(struct in_addr)) + goto send_mal_query; + dev = ip_dev_find(net, iio->ident.addr.ip_addr.ipv4_addr); + break; +#if IS_ENABLED(CONFIG_IPV6) + case ICMP_AFI_IP6: + if (iio->ident.addr.ctype3_hdr.addrlen != sizeof(struct in6_addr)) + goto send_mal_query; + dev = ipv6_stub->ipv6_dev_find(net, &iio->ident.addr.ip_addr.ipv6_addr, dev); + dev_hold(dev); + break; +#endif + default: + goto send_mal_query; + } + break; + default: + goto send_mal_query; + } + if (!dev) { + icmphdr->code = ICMP_EXT_CODE_NO_IF; + return true; + } + /* Fill bits in reply message */ + if (dev->flags & IFF_UP) + status |= ICMP_EXT_ECHOREPLY_ACTIVE; + if (__in_dev_get_rcu(dev) && __in_dev_get_rcu(dev)->ifa_list) + status |= ICMP_EXT_ECHOREPLY_IPV4; + if (!list_empty(&rcu_dereference(dev->ip6_ptr)->addr_list)) + status |= ICMP_EXT_ECHOREPLY_IPV6; + dev_put(dev); + icmphdr->un.echo.sequence |= htons(status); + return true; +send_mal_query: + icmphdr->code = ICMP_EXT_CODE_MAL_QUERY; + return true; +} +EXPORT_SYMBOL_GPL(icmp_build_probe); + +/* + * 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 enum skb_drop_reason 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 SKB_NOT_DROPPED_YET; + +out_err: + __ICMP_INC_STATS(dev_net(skb_dst(skb)->dev), ICMP_MIB_INERRORS); + return SKB_DROP_REASON_PKT_TOO_SMALL; +} + +static enum skb_drop_reason icmp_discard(struct sk_buff *skb) +{ + /* pretend it was a success */ + return SKB_NOT_DROPPED_YET; +} + +/* + * Deal with incoming ICMP packets. + */ +int icmp_rcv(struct sk_buff *skb) +{ + enum skb_drop_reason reason = SKB_DROP_REASON_NOT_SPECIFIED; + struct rtable *rt = skb_rtable(skb); + struct net *net = dev_net(rt->dst.dev); + struct icmphdr *icmph; + + 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)) { + reason = SKB_DROP_REASON_XFRM_POLICY; + 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)) { + reason = SKB_DROP_REASON_XFRM_POLICY; + 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); + + /* Check for ICMP Extended Echo (PROBE) messages */ + if (icmph->type == ICMP_EXT_ECHO) { + /* We can't use icmp_pointers[].handler() because it is an array of + * size NR_ICMP_TYPES + 1 (19 elements) and PROBE has code 42. + */ + reason = icmp_echo(skb); + goto reason_check; + } + + if (icmph->type == ICMP_EXT_ECHOREPLY) { + reason = ping_rcv(skb); + goto reason_check; + } + + /* + * 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) { + reason = SKB_DROP_REASON_UNHANDLED_PROTO; + 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) && + READ_ONCE(net->ipv4.sysctl_icmp_echo_ignore_broadcasts)) { + reason = SKB_DROP_REASON_INVALID_PROTO; + goto error; + } + if (icmph->type != ICMP_ECHO && + icmph->type != ICMP_TIMESTAMP && + icmph->type != ICMP_ADDRESS && + icmph->type != ICMP_ADDRESSREPLY) { + reason = SKB_DROP_REASON_INVALID_PROTO; + goto error; + } + } + + reason = icmp_pointers[icmph->type].handler(skb); +reason_check: + if (!reason) { + consume_skb(skb); + return NET_RX_SUCCESS; + } + +drop: + kfree_skb_reason(skb, reason); + return NET_RX_DROP; +csum_error: + reason = SKB_DROP_REASON_ICMP_CSUM; + __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 int __net_init icmp_sk_init(struct net *net) +{ + /* Control parameters for ECHO replies. */ + net->ipv4.sysctl_icmp_echo_ignore_all = 0; + net->ipv4.sysctl_icmp_echo_enable_probe = 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; +} + +static struct pernet_operations __net_initdata icmp_sk_ops = { + .init = icmp_sk_init, +}; + +int __init icmp_init(void) +{ + int err, i; + + for_each_possible_cpu(i) { + struct sock *sk; + + err = inet_ctl_sock_create(&sk, PF_INET, + SOCK_RAW, IPPROTO_ICMP, &init_net); + if (err < 0) + return err; + + per_cpu(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; + } + return register_pernet_subsys(&icmp_sk_ops); +} -- cgit v1.2.3