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/ip_input.c | 675 ++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 675 insertions(+) create mode 100644 net/ipv4/ip_input.c (limited to 'net/ipv4/ip_input.c') diff --git a/net/ipv4/ip_input.c b/net/ipv4/ip_input.c new file mode 100644 index 0000000000..5e9c815665 --- /dev/null +++ b/net/ipv4/ip_input.c @@ -0,0 +1,675 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * 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. + * + * The Internet Protocol (IP) module. + * + * Authors: Ross Biro + * Fred N. van Kempen, + * Donald Becker, + * Alan Cox, + * Richard Underwood + * Stefan Becker, + * Jorge Cwik, + * Arnt Gulbrandsen, + * + * Fixes: + * Alan Cox : Commented a couple of minor bits of surplus code + * Alan Cox : Undefining IP_FORWARD doesn't include the code + * (just stops a compiler warning). + * Alan Cox : Frames with >=MAX_ROUTE record routes, strict routes or loose routes + * are junked rather than corrupting things. + * Alan Cox : Frames to bad broadcast subnets are dumped + * We used to process them non broadcast and + * boy could that cause havoc. + * Alan Cox : ip_forward sets the free flag on the + * new frame it queues. Still crap because + * it copies the frame but at least it + * doesn't eat memory too. + * Alan Cox : Generic queue code and memory fixes. + * Fred Van Kempen : IP fragment support (borrowed from NET2E) + * Gerhard Koerting: Forward fragmented frames correctly. + * Gerhard Koerting: Fixes to my fix of the above 8-). + * Gerhard Koerting: IP interface addressing fix. + * Linus Torvalds : More robustness checks + * Alan Cox : Even more checks: Still not as robust as it ought to be + * Alan Cox : Save IP header pointer for later + * Alan Cox : ip option setting + * Alan Cox : Use ip_tos/ip_ttl settings + * Alan Cox : Fragmentation bogosity removed + * (Thanks to Mark.Bush@prg.ox.ac.uk) + * Dmitry Gorodchanin : Send of a raw packet crash fix. + * Alan Cox : Silly ip bug when an overlength + * fragment turns up. Now frees the + * queue. + * Linus Torvalds/ : Memory leakage on fragmentation + * Alan Cox : handling. + * Gerhard Koerting: Forwarding uses IP priority hints + * Teemu Rantanen : Fragment problems. + * Alan Cox : General cleanup, comments and reformat + * Alan Cox : SNMP statistics + * Alan Cox : BSD address rule semantics. Also see + * UDP as there is a nasty checksum issue + * if you do things the wrong way. + * Alan Cox : Always defrag, moved IP_FORWARD to the config.in file + * Alan Cox : IP options adjust sk->priority. + * Pedro Roque : Fix mtu/length error in ip_forward. + * Alan Cox : Avoid ip_chk_addr when possible. + * Richard Underwood : IP multicasting. + * Alan Cox : Cleaned up multicast handlers. + * Alan Cox : RAW sockets demultiplex in the BSD style. + * Gunther Mayer : Fix the SNMP reporting typo + * Alan Cox : Always in group 224.0.0.1 + * Pauline Middelink : Fast ip_checksum update when forwarding + * Masquerading support. + * Alan Cox : Multicast loopback error for 224.0.0.1 + * Alan Cox : IP_MULTICAST_LOOP option. + * Alan Cox : Use notifiers. + * Bjorn Ekwall : Removed ip_csum (from slhc.c too) + * Bjorn Ekwall : Moved ip_fast_csum to ip.h (inline!) + * Stefan Becker : Send out ICMP HOST REDIRECT + * Arnt Gulbrandsen : ip_build_xmit + * Alan Cox : Per socket routing cache + * Alan Cox : Fixed routing cache, added header cache. + * Alan Cox : Loopback didn't work right in original ip_build_xmit - fixed it. + * Alan Cox : Only send ICMP_REDIRECT if src/dest are the same net. + * Alan Cox : Incoming IP option handling. + * Alan Cox : Set saddr on raw output frames as per BSD. + * Alan Cox : Stopped broadcast source route explosions. + * Alan Cox : Can disable source routing + * Takeshi Sone : Masquerading didn't work. + * Dave Bonn,Alan Cox : Faster IP forwarding whenever possible. + * Alan Cox : Memory leaks, tramples, misc debugging. + * Alan Cox : Fixed multicast (by popular demand 8)) + * Alan Cox : Fixed forwarding (by even more popular demand 8)) + * Alan Cox : Fixed SNMP statistics [I think] + * Gerhard Koerting : IP fragmentation forwarding fix + * Alan Cox : Device lock against page fault. + * Alan Cox : IP_HDRINCL facility. + * Werner Almesberger : Zero fragment bug + * Alan Cox : RAW IP frame length bug + * Alan Cox : Outgoing firewall on build_xmit + * A.N.Kuznetsov : IP_OPTIONS support throughout the kernel + * Alan Cox : Multicast routing hooks + * Jos Vos : Do accounting *before* call_in_firewall + * Willy Konynenberg : Transparent proxying support + * + * To Fix: + * IP fragmentation wants rewriting cleanly. The RFC815 algorithm is much more efficient + * and could be made very efficient with the addition of some virtual memory hacks to permit + * the allocation of a buffer that can then be 'grown' by twiddling page tables. + * Output fragmentation wants updating along with the buffer management to use a single + * interleaved copy algorithm so that fragmenting has a one copy overhead. Actual packet + * output should probably do its own fragmentation at the UDP/RAW layer. TCP shouldn't cause + * fragmentation anyway. + */ + +#define pr_fmt(fmt) "IPv4: " 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 + +/* + * Process Router Attention IP option (RFC 2113) + */ +bool ip_call_ra_chain(struct sk_buff *skb) +{ + struct ip_ra_chain *ra; + u8 protocol = ip_hdr(skb)->protocol; + struct sock *last = NULL; + struct net_device *dev = skb->dev; + struct net *net = dev_net(dev); + + for (ra = rcu_dereference(net->ipv4.ra_chain); ra; ra = rcu_dereference(ra->next)) { + struct sock *sk = ra->sk; + + /* If socket is bound to an interface, only report + * the packet if it came from that interface. + */ + if (sk && inet_sk(sk)->inet_num == protocol && + (!sk->sk_bound_dev_if || + sk->sk_bound_dev_if == dev->ifindex)) { + if (ip_is_fragment(ip_hdr(skb))) { + if (ip_defrag(net, skb, IP_DEFRAG_CALL_RA_CHAIN)) + return true; + } + if (last) { + struct sk_buff *skb2 = skb_clone(skb, GFP_ATOMIC); + if (skb2) + raw_rcv(last, skb2); + } + last = sk; + } + } + + if (last) { + raw_rcv(last, skb); + return true; + } + return false; +} + +INDIRECT_CALLABLE_DECLARE(int udp_rcv(struct sk_buff *)); +INDIRECT_CALLABLE_DECLARE(int tcp_v4_rcv(struct sk_buff *)); +void ip_protocol_deliver_rcu(struct net *net, struct sk_buff *skb, int protocol) +{ + const struct net_protocol *ipprot; + int raw, ret; + +resubmit: + raw = raw_local_deliver(skb, protocol); + + ipprot = rcu_dereference(inet_protos[protocol]); + if (ipprot) { + if (!ipprot->no_policy) { + if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) { + kfree_skb_reason(skb, + SKB_DROP_REASON_XFRM_POLICY); + return; + } + nf_reset_ct(skb); + } + ret = INDIRECT_CALL_2(ipprot->handler, tcp_v4_rcv, udp_rcv, + skb); + if (ret < 0) { + protocol = -ret; + goto resubmit; + } + __IP_INC_STATS(net, IPSTATS_MIB_INDELIVERS); + } else { + if (!raw) { + if (xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) { + __IP_INC_STATS(net, IPSTATS_MIB_INUNKNOWNPROTOS); + icmp_send(skb, ICMP_DEST_UNREACH, + ICMP_PROT_UNREACH, 0); + } + kfree_skb_reason(skb, SKB_DROP_REASON_IP_NOPROTO); + } else { + __IP_INC_STATS(net, IPSTATS_MIB_INDELIVERS); + consume_skb(skb); + } + } +} + +static int ip_local_deliver_finish(struct net *net, struct sock *sk, struct sk_buff *skb) +{ + skb_clear_delivery_time(skb); + __skb_pull(skb, skb_network_header_len(skb)); + + rcu_read_lock(); + ip_protocol_deliver_rcu(net, skb, ip_hdr(skb)->protocol); + rcu_read_unlock(); + + return 0; +} + +/* + * Deliver IP Packets to the higher protocol layers. + */ +int ip_local_deliver(struct sk_buff *skb) +{ + /* + * Reassemble IP fragments. + */ + struct net *net = dev_net(skb->dev); + + if (ip_is_fragment(ip_hdr(skb))) { + if (ip_defrag(net, skb, IP_DEFRAG_LOCAL_DELIVER)) + return 0; + } + + return NF_HOOK(NFPROTO_IPV4, NF_INET_LOCAL_IN, + net, NULL, skb, skb->dev, NULL, + ip_local_deliver_finish); +} +EXPORT_SYMBOL(ip_local_deliver); + +static inline bool ip_rcv_options(struct sk_buff *skb, struct net_device *dev) +{ + struct ip_options *opt; + const struct iphdr *iph; + + /* It looks as overkill, because not all + IP options require packet mangling. + But it is the easiest for now, especially taking + into account that combination of IP options + and running sniffer is extremely rare condition. + --ANK (980813) + */ + if (skb_cow(skb, skb_headroom(skb))) { + __IP_INC_STATS(dev_net(dev), IPSTATS_MIB_INDISCARDS); + goto drop; + } + + iph = ip_hdr(skb); + opt = &(IPCB(skb)->opt); + opt->optlen = iph->ihl*4 - sizeof(struct iphdr); + + if (ip_options_compile(dev_net(dev), opt, skb)) { + __IP_INC_STATS(dev_net(dev), IPSTATS_MIB_INHDRERRORS); + goto drop; + } + + if (unlikely(opt->srr)) { + struct in_device *in_dev = __in_dev_get_rcu(dev); + + if (in_dev) { + if (!IN_DEV_SOURCE_ROUTE(in_dev)) { + if (IN_DEV_LOG_MARTIANS(in_dev)) + net_info_ratelimited("source route option %pI4 -> %pI4\n", + &iph->saddr, + &iph->daddr); + goto drop; + } + } + + if (ip_options_rcv_srr(skb, dev)) + goto drop; + } + + return false; +drop: + return true; +} + +static bool ip_can_use_hint(const struct sk_buff *skb, const struct iphdr *iph, + const struct sk_buff *hint) +{ + return hint && !skb_dst(skb) && ip_hdr(hint)->daddr == iph->daddr && + ip_hdr(hint)->tos == iph->tos; +} + +int tcp_v4_early_demux(struct sk_buff *skb); +int udp_v4_early_demux(struct sk_buff *skb); +static int ip_rcv_finish_core(struct net *net, struct sock *sk, + struct sk_buff *skb, struct net_device *dev, + const struct sk_buff *hint) +{ + const struct iphdr *iph = ip_hdr(skb); + int err, drop_reason; + struct rtable *rt; + + drop_reason = SKB_DROP_REASON_NOT_SPECIFIED; + + if (ip_can_use_hint(skb, iph, hint)) { + err = ip_route_use_hint(skb, iph->daddr, iph->saddr, iph->tos, + dev, hint); + if (unlikely(err)) + goto drop_error; + } + + if (READ_ONCE(net->ipv4.sysctl_ip_early_demux) && + !skb_dst(skb) && + !skb->sk && + !ip_is_fragment(iph)) { + switch (iph->protocol) { + case IPPROTO_TCP: + if (READ_ONCE(net->ipv4.sysctl_tcp_early_demux)) { + tcp_v4_early_demux(skb); + + /* must reload iph, skb->head might have changed */ + iph = ip_hdr(skb); + } + break; + case IPPROTO_UDP: + if (READ_ONCE(net->ipv4.sysctl_udp_early_demux)) { + err = udp_v4_early_demux(skb); + if (unlikely(err)) + goto drop_error; + + /* must reload iph, skb->head might have changed */ + iph = ip_hdr(skb); + } + break; + } + } + + /* + * Initialise the virtual path cache for the packet. It describes + * how the packet travels inside Linux networking. + */ + if (!skb_valid_dst(skb)) { + err = ip_route_input_noref(skb, iph->daddr, iph->saddr, + iph->tos, dev); + if (unlikely(err)) + goto drop_error; + } else { + struct in_device *in_dev = __in_dev_get_rcu(dev); + + if (in_dev && IN_DEV_ORCONF(in_dev, NOPOLICY)) + IPCB(skb)->flags |= IPSKB_NOPOLICY; + } + +#ifdef CONFIG_IP_ROUTE_CLASSID + if (unlikely(skb_dst(skb)->tclassid)) { + struct ip_rt_acct *st = this_cpu_ptr(ip_rt_acct); + u32 idx = skb_dst(skb)->tclassid; + st[idx&0xFF].o_packets++; + st[idx&0xFF].o_bytes += skb->len; + st[(idx>>16)&0xFF].i_packets++; + st[(idx>>16)&0xFF].i_bytes += skb->len; + } +#endif + + if (iph->ihl > 5 && ip_rcv_options(skb, dev)) + goto drop; + + rt = skb_rtable(skb); + if (rt->rt_type == RTN_MULTICAST) { + __IP_UPD_PO_STATS(net, IPSTATS_MIB_INMCAST, skb->len); + } else if (rt->rt_type == RTN_BROADCAST) { + __IP_UPD_PO_STATS(net, IPSTATS_MIB_INBCAST, skb->len); + } else if (skb->pkt_type == PACKET_BROADCAST || + skb->pkt_type == PACKET_MULTICAST) { + struct in_device *in_dev = __in_dev_get_rcu(dev); + + /* RFC 1122 3.3.6: + * + * When a host sends a datagram to a link-layer broadcast + * address, the IP destination address MUST be a legal IP + * broadcast or IP multicast address. + * + * A host SHOULD silently discard a datagram that is received + * via a link-layer broadcast (see Section 2.4) but does not + * specify an IP multicast or broadcast destination address. + * + * This doesn't explicitly say L2 *broadcast*, but broadcast is + * in a way a form of multicast and the most common use case for + * this is 802.11 protecting against cross-station spoofing (the + * so-called "hole-196" attack) so do it for both. + */ + if (in_dev && + IN_DEV_ORCONF(in_dev, DROP_UNICAST_IN_L2_MULTICAST)) { + drop_reason = SKB_DROP_REASON_UNICAST_IN_L2_MULTICAST; + goto drop; + } + } + + return NET_RX_SUCCESS; + +drop: + kfree_skb_reason(skb, drop_reason); + return NET_RX_DROP; + +drop_error: + if (err == -EXDEV) { + drop_reason = SKB_DROP_REASON_IP_RPFILTER; + __NET_INC_STATS(net, LINUX_MIB_IPRPFILTER); + } + goto drop; +} + +static int ip_rcv_finish(struct net *net, struct sock *sk, struct sk_buff *skb) +{ + struct net_device *dev = skb->dev; + int ret; + + /* if ingress device is enslaved to an L3 master device pass the + * skb to its handler for processing + */ + skb = l3mdev_ip_rcv(skb); + if (!skb) + return NET_RX_SUCCESS; + + ret = ip_rcv_finish_core(net, sk, skb, dev, NULL); + if (ret != NET_RX_DROP) + ret = dst_input(skb); + return ret; +} + +/* + * Main IP Receive routine. + */ +static struct sk_buff *ip_rcv_core(struct sk_buff *skb, struct net *net) +{ + const struct iphdr *iph; + int drop_reason; + u32 len; + + /* When the interface is in promisc. mode, drop all the crap + * that it receives, do not try to analyse it. + */ + if (skb->pkt_type == PACKET_OTHERHOST) { + dev_core_stats_rx_otherhost_dropped_inc(skb->dev); + drop_reason = SKB_DROP_REASON_OTHERHOST; + goto drop; + } + + __IP_UPD_PO_STATS(net, IPSTATS_MIB_IN, skb->len); + + skb = skb_share_check(skb, GFP_ATOMIC); + if (!skb) { + __IP_INC_STATS(net, IPSTATS_MIB_INDISCARDS); + goto out; + } + + drop_reason = SKB_DROP_REASON_NOT_SPECIFIED; + if (!pskb_may_pull(skb, sizeof(struct iphdr))) + goto inhdr_error; + + iph = ip_hdr(skb); + + /* + * RFC1122: 3.2.1.2 MUST silently discard any IP frame that fails the checksum. + * + * Is the datagram acceptable? + * + * 1. Length at least the size of an ip header + * 2. Version of 4 + * 3. Checksums correctly. [Speed optimisation for later, skip loopback checksums] + * 4. Doesn't have a bogus length + */ + + if (iph->ihl < 5 || iph->version != 4) + goto inhdr_error; + + BUILD_BUG_ON(IPSTATS_MIB_ECT1PKTS != IPSTATS_MIB_NOECTPKTS + INET_ECN_ECT_1); + BUILD_BUG_ON(IPSTATS_MIB_ECT0PKTS != IPSTATS_MIB_NOECTPKTS + INET_ECN_ECT_0); + BUILD_BUG_ON(IPSTATS_MIB_CEPKTS != IPSTATS_MIB_NOECTPKTS + INET_ECN_CE); + __IP_ADD_STATS(net, + IPSTATS_MIB_NOECTPKTS + (iph->tos & INET_ECN_MASK), + max_t(unsigned short, 1, skb_shinfo(skb)->gso_segs)); + + if (!pskb_may_pull(skb, iph->ihl*4)) + goto inhdr_error; + + iph = ip_hdr(skb); + + if (unlikely(ip_fast_csum((u8 *)iph, iph->ihl))) + goto csum_error; + + len = iph_totlen(skb, iph); + if (skb->len < len) { + drop_reason = SKB_DROP_REASON_PKT_TOO_SMALL; + __IP_INC_STATS(net, IPSTATS_MIB_INTRUNCATEDPKTS); + goto drop; + } else if (len < (iph->ihl*4)) + goto inhdr_error; + + /* Our transport medium may have padded the buffer out. Now we know it + * is IP we can trim to the true length of the frame. + * Note this now means skb->len holds ntohs(iph->tot_len). + */ + if (pskb_trim_rcsum(skb, len)) { + __IP_INC_STATS(net, IPSTATS_MIB_INDISCARDS); + goto drop; + } + + iph = ip_hdr(skb); + skb->transport_header = skb->network_header + iph->ihl*4; + + /* Remove any debris in the socket control block */ + memset(IPCB(skb), 0, sizeof(struct inet_skb_parm)); + IPCB(skb)->iif = skb->skb_iif; + + /* Must drop socket now because of tproxy. */ + if (!skb_sk_is_prefetched(skb)) + skb_orphan(skb); + + return skb; + +csum_error: + drop_reason = SKB_DROP_REASON_IP_CSUM; + __IP_INC_STATS(net, IPSTATS_MIB_CSUMERRORS); +inhdr_error: + if (drop_reason == SKB_DROP_REASON_NOT_SPECIFIED) + drop_reason = SKB_DROP_REASON_IP_INHDR; + __IP_INC_STATS(net, IPSTATS_MIB_INHDRERRORS); +drop: + kfree_skb_reason(skb, drop_reason); +out: + return NULL; +} + +/* + * IP receive entry point + */ +int ip_rcv(struct sk_buff *skb, struct net_device *dev, struct packet_type *pt, + struct net_device *orig_dev) +{ + struct net *net = dev_net(dev); + + skb = ip_rcv_core(skb, net); + if (skb == NULL) + return NET_RX_DROP; + + return NF_HOOK(NFPROTO_IPV4, NF_INET_PRE_ROUTING, + net, NULL, skb, dev, NULL, + ip_rcv_finish); +} + +static void ip_sublist_rcv_finish(struct list_head *head) +{ + struct sk_buff *skb, *next; + + list_for_each_entry_safe(skb, next, head, list) { + skb_list_del_init(skb); + dst_input(skb); + } +} + +static struct sk_buff *ip_extract_route_hint(const struct net *net, + struct sk_buff *skb, int rt_type) +{ + if (fib4_has_custom_rules(net) || rt_type == RTN_BROADCAST || + IPCB(skb)->flags & IPSKB_MULTIPATH) + return NULL; + + return skb; +} + +static void ip_list_rcv_finish(struct net *net, struct sock *sk, + struct list_head *head) +{ + struct sk_buff *skb, *next, *hint = NULL; + struct dst_entry *curr_dst = NULL; + struct list_head sublist; + + INIT_LIST_HEAD(&sublist); + list_for_each_entry_safe(skb, next, head, list) { + struct net_device *dev = skb->dev; + struct dst_entry *dst; + + skb_list_del_init(skb); + /* if ingress device is enslaved to an L3 master device pass the + * skb to its handler for processing + */ + skb = l3mdev_ip_rcv(skb); + if (!skb) + continue; + if (ip_rcv_finish_core(net, sk, skb, dev, hint) == NET_RX_DROP) + continue; + + dst = skb_dst(skb); + if (curr_dst != dst) { + hint = ip_extract_route_hint(net, skb, + ((struct rtable *)dst)->rt_type); + + /* dispatch old sublist */ + if (!list_empty(&sublist)) + ip_sublist_rcv_finish(&sublist); + /* start new sublist */ + INIT_LIST_HEAD(&sublist); + curr_dst = dst; + } + list_add_tail(&skb->list, &sublist); + } + /* dispatch final sublist */ + ip_sublist_rcv_finish(&sublist); +} + +static void ip_sublist_rcv(struct list_head *head, struct net_device *dev, + struct net *net) +{ + NF_HOOK_LIST(NFPROTO_IPV4, NF_INET_PRE_ROUTING, net, NULL, + head, dev, NULL, ip_rcv_finish); + ip_list_rcv_finish(net, NULL, head); +} + +/* Receive a list of IP packets */ +void ip_list_rcv(struct list_head *head, struct packet_type *pt, + struct net_device *orig_dev) +{ + struct net_device *curr_dev = NULL; + struct net *curr_net = NULL; + struct sk_buff *skb, *next; + struct list_head sublist; + + INIT_LIST_HEAD(&sublist); + list_for_each_entry_safe(skb, next, head, list) { + struct net_device *dev = skb->dev; + struct net *net = dev_net(dev); + + skb_list_del_init(skb); + skb = ip_rcv_core(skb, net); + if (skb == NULL) + continue; + + if (curr_dev != dev || curr_net != net) { + /* dispatch old sublist */ + if (!list_empty(&sublist)) + ip_sublist_rcv(&sublist, curr_dev, curr_net); + /* start new sublist */ + INIT_LIST_HEAD(&sublist); + curr_dev = dev; + curr_net = net; + } + list_add_tail(&skb->list, &sublist); + } + /* dispatch final sublist */ + if (!list_empty(&sublist)) + ip_sublist_rcv(&sublist, curr_dev, curr_net); +} -- cgit v1.2.3