diff options
Diffstat (limited to 'net/ipv6/netfilter/nf_conntrack_reasm.c')
-rw-r--r-- | net/ipv6/netfilter/nf_conntrack_reasm.c | 568 |
1 files changed, 568 insertions, 0 deletions
diff --git a/net/ipv6/netfilter/nf_conntrack_reasm.c b/net/ipv6/netfilter/nf_conntrack_reasm.c new file mode 100644 index 000000000..38db0064d --- /dev/null +++ b/net/ipv6/netfilter/nf_conntrack_reasm.c @@ -0,0 +1,568 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * IPv6 fragment reassembly for connection tracking + * + * Copyright (C)2004 USAGI/WIDE Project + * + * Author: + * Yasuyuki Kozakai @USAGI <yasuyuki.kozakai@toshiba.co.jp> + * + * Based on: net/ipv6/reassembly.c + */ + +#define pr_fmt(fmt) "IPv6-nf: " fmt + +#include <linux/errno.h> +#include <linux/types.h> +#include <linux/string.h> +#include <linux/net.h> +#include <linux/netdevice.h> +#include <linux/ipv6.h> +#include <linux/slab.h> + +#include <net/ipv6_frag.h> + +#include <net/netfilter/ipv6/nf_conntrack_ipv6.h> +#include <linux/sysctl.h> +#include <linux/netfilter.h> +#include <linux/netfilter_ipv6.h> +#include <linux/kernel.h> +#include <linux/module.h> +#include <net/netfilter/ipv6/nf_defrag_ipv6.h> +#include <net/netns/generic.h> + +static const char nf_frags_cache_name[] = "nf-frags"; + +static unsigned int nf_frag_pernet_id __read_mostly; +static struct inet_frags nf_frags; + +static struct nft_ct_frag6_pernet *nf_frag_pernet(struct net *net) +{ + return net_generic(net, nf_frag_pernet_id); +} + +#ifdef CONFIG_SYSCTL + +static struct ctl_table nf_ct_frag6_sysctl_table[] = { + { + .procname = "nf_conntrack_frag6_timeout", + .maxlen = sizeof(unsigned int), + .mode = 0644, + .proc_handler = proc_dointvec_jiffies, + }, + { + .procname = "nf_conntrack_frag6_low_thresh", + .maxlen = sizeof(unsigned long), + .mode = 0644, + .proc_handler = proc_doulongvec_minmax, + }, + { + .procname = "nf_conntrack_frag6_high_thresh", + .maxlen = sizeof(unsigned long), + .mode = 0644, + .proc_handler = proc_doulongvec_minmax, + }, + { } +}; + +static int nf_ct_frag6_sysctl_register(struct net *net) +{ + struct nft_ct_frag6_pernet *nf_frag; + struct ctl_table *table; + struct ctl_table_header *hdr; + + table = nf_ct_frag6_sysctl_table; + if (!net_eq(net, &init_net)) { + table = kmemdup(table, sizeof(nf_ct_frag6_sysctl_table), + GFP_KERNEL); + if (table == NULL) + goto err_alloc; + } + + nf_frag = nf_frag_pernet(net); + + table[0].data = &nf_frag->fqdir->timeout; + table[1].data = &nf_frag->fqdir->low_thresh; + table[1].extra2 = &nf_frag->fqdir->high_thresh; + table[2].data = &nf_frag->fqdir->high_thresh; + table[2].extra1 = &nf_frag->fqdir->low_thresh; + + hdr = register_net_sysctl(net, "net/netfilter", table); + if (hdr == NULL) + goto err_reg; + + nf_frag->nf_frag_frags_hdr = hdr; + return 0; + +err_reg: + if (!net_eq(net, &init_net)) + kfree(table); +err_alloc: + return -ENOMEM; +} + +static void __net_exit nf_ct_frags6_sysctl_unregister(struct net *net) +{ + struct nft_ct_frag6_pernet *nf_frag = nf_frag_pernet(net); + struct ctl_table *table; + + table = nf_frag->nf_frag_frags_hdr->ctl_table_arg; + unregister_net_sysctl_table(nf_frag->nf_frag_frags_hdr); + if (!net_eq(net, &init_net)) + kfree(table); +} + +#else +static int nf_ct_frag6_sysctl_register(struct net *net) +{ + return 0; +} +static void __net_exit nf_ct_frags6_sysctl_unregister(struct net *net) +{ +} +#endif + +static int nf_ct_frag6_reasm(struct frag_queue *fq, struct sk_buff *skb, + struct sk_buff *prev_tail, struct net_device *dev); + +static inline u8 ip6_frag_ecn(const struct ipv6hdr *ipv6h) +{ + return 1 << (ipv6_get_dsfield(ipv6h) & INET_ECN_MASK); +} + +static void nf_ct_frag6_expire(struct timer_list *t) +{ + struct inet_frag_queue *frag = from_timer(frag, t, timer); + struct frag_queue *fq; + + fq = container_of(frag, struct frag_queue, q); + + ip6frag_expire_frag_queue(fq->q.fqdir->net, fq); +} + +/* Creation primitives. */ +static struct frag_queue *fq_find(struct net *net, __be32 id, u32 user, + const struct ipv6hdr *hdr, int iif) +{ + struct nft_ct_frag6_pernet *nf_frag = nf_frag_pernet(net); + struct frag_v6_compare_key key = { + .id = id, + .saddr = hdr->saddr, + .daddr = hdr->daddr, + .user = user, + .iif = iif, + }; + struct inet_frag_queue *q; + + q = inet_frag_find(nf_frag->fqdir, &key); + if (!q) + return NULL; + + return container_of(q, struct frag_queue, q); +} + + +static int nf_ct_frag6_queue(struct frag_queue *fq, struct sk_buff *skb, + const struct frag_hdr *fhdr, int nhoff) +{ + unsigned int payload_len; + struct net_device *dev; + struct sk_buff *prev; + int offset, end, err; + u8 ecn; + + if (fq->q.flags & INET_FRAG_COMPLETE) { + pr_debug("Already completed\n"); + goto err; + } + + payload_len = ntohs(ipv6_hdr(skb)->payload_len); + + offset = ntohs(fhdr->frag_off) & ~0x7; + end = offset + (payload_len - + ((u8 *)(fhdr + 1) - (u8 *)(ipv6_hdr(skb) + 1))); + + if ((unsigned int)end > IPV6_MAXPLEN) { + pr_debug("offset is too large.\n"); + return -EINVAL; + } + + ecn = ip6_frag_ecn(ipv6_hdr(skb)); + + if (skb->ip_summed == CHECKSUM_COMPLETE) { + const unsigned char *nh = skb_network_header(skb); + skb->csum = csum_sub(skb->csum, + csum_partial(nh, (u8 *)(fhdr + 1) - nh, + 0)); + } + + /* Is this the final fragment? */ + if (!(fhdr->frag_off & htons(IP6_MF))) { + /* If we already have some bits beyond end + * or have different end, the segment is corrupted. + */ + if (end < fq->q.len || + ((fq->q.flags & INET_FRAG_LAST_IN) && end != fq->q.len)) { + pr_debug("already received last fragment\n"); + goto err; + } + fq->q.flags |= INET_FRAG_LAST_IN; + fq->q.len = end; + } else { + /* Check if the fragment is rounded to 8 bytes. + * Required by the RFC. + */ + if (end & 0x7) { + /* RFC2460 says always send parameter problem in + * this case. -DaveM + */ + pr_debug("end of fragment not rounded to 8 bytes.\n"); + inet_frag_kill(&fq->q); + return -EPROTO; + } + if (end > fq->q.len) { + /* Some bits beyond end -> corruption. */ + if (fq->q.flags & INET_FRAG_LAST_IN) { + pr_debug("last packet already reached.\n"); + goto err; + } + fq->q.len = end; + } + } + + if (end == offset) + goto err; + + /* Point into the IP datagram 'data' part. */ + if (!pskb_pull(skb, (u8 *) (fhdr + 1) - skb->data)) { + pr_debug("queue: message is too short.\n"); + goto err; + } + if (pskb_trim_rcsum(skb, end - offset)) { + pr_debug("Can't trim\n"); + goto err; + } + + /* Note : skb->rbnode and skb->dev share the same location. */ + dev = skb->dev; + /* Makes sure compiler wont do silly aliasing games */ + barrier(); + + prev = fq->q.fragments_tail; + err = inet_frag_queue_insert(&fq->q, skb, offset, end); + if (err) { + if (err == IPFRAG_DUP) { + /* No error for duplicates, pretend they got queued. */ + kfree_skb(skb); + return -EINPROGRESS; + } + goto insert_error; + } + + if (dev) + fq->iif = dev->ifindex; + + fq->q.stamp = skb->tstamp; + fq->q.mono_delivery_time = skb->mono_delivery_time; + fq->q.meat += skb->len; + fq->ecn |= ecn; + if (payload_len > fq->q.max_size) + fq->q.max_size = payload_len; + add_frag_mem_limit(fq->q.fqdir, skb->truesize); + + /* The first fragment. + * nhoffset is obtained from the first fragment, of course. + */ + if (offset == 0) { + fq->nhoffset = nhoff; + fq->q.flags |= INET_FRAG_FIRST_IN; + } + + if (fq->q.flags == (INET_FRAG_FIRST_IN | INET_FRAG_LAST_IN) && + fq->q.meat == fq->q.len) { + unsigned long orefdst = skb->_skb_refdst; + + skb->_skb_refdst = 0UL; + err = nf_ct_frag6_reasm(fq, skb, prev, dev); + skb->_skb_refdst = orefdst; + + /* After queue has assumed skb ownership, only 0 or + * -EINPROGRESS must be returned. + */ + return err ? -EINPROGRESS : 0; + } + + skb_dst_drop(skb); + return -EINPROGRESS; + +insert_error: + inet_frag_kill(&fq->q); +err: + skb_dst_drop(skb); + return -EINVAL; +} + +/* + * Check if this packet is complete. + * + * It is called with locked fq, and caller must check that + * queue is eligible for reassembly i.e. it is not COMPLETE, + * the last and the first frames arrived and all the bits are here. + */ +static int nf_ct_frag6_reasm(struct frag_queue *fq, struct sk_buff *skb, + struct sk_buff *prev_tail, struct net_device *dev) +{ + void *reasm_data; + int payload_len; + u8 ecn; + + inet_frag_kill(&fq->q); + + ecn = ip_frag_ecn_table[fq->ecn]; + if (unlikely(ecn == 0xff)) + goto err; + + reasm_data = inet_frag_reasm_prepare(&fq->q, skb, prev_tail); + if (!reasm_data) + goto err; + + payload_len = ((skb->data - skb_network_header(skb)) - + sizeof(struct ipv6hdr) + fq->q.len - + sizeof(struct frag_hdr)); + if (payload_len > IPV6_MAXPLEN) { + net_dbg_ratelimited("nf_ct_frag6_reasm: payload len = %d\n", + payload_len); + goto err; + } + + /* We have to remove fragment header from datagram and to relocate + * header in order to calculate ICV correctly. */ + skb_network_header(skb)[fq->nhoffset] = skb_transport_header(skb)[0]; + memmove(skb->head + sizeof(struct frag_hdr), skb->head, + (skb->data - skb->head) - sizeof(struct frag_hdr)); + skb->mac_header += sizeof(struct frag_hdr); + skb->network_header += sizeof(struct frag_hdr); + + skb_reset_transport_header(skb); + + inet_frag_reasm_finish(&fq->q, skb, reasm_data, false); + + skb->ignore_df = 1; + skb->dev = dev; + ipv6_hdr(skb)->payload_len = htons(payload_len); + ipv6_change_dsfield(ipv6_hdr(skb), 0xff, ecn); + IP6CB(skb)->frag_max_size = sizeof(struct ipv6hdr) + fq->q.max_size; + IP6CB(skb)->flags |= IP6SKB_FRAGMENTED; + + /* Yes, and fold redundant checksum back. 8) */ + if (skb->ip_summed == CHECKSUM_COMPLETE) + skb->csum = csum_partial(skb_network_header(skb), + skb_network_header_len(skb), + skb->csum); + + fq->q.rb_fragments = RB_ROOT; + fq->q.fragments_tail = NULL; + fq->q.last_run_head = NULL; + + return 0; + +err: + inet_frag_kill(&fq->q); + return -EINVAL; +} + +/* + * find the header just before Fragment Header. + * + * if success return 0 and set ... + * (*prevhdrp): the value of "Next Header Field" in the header + * just before Fragment Header. + * (*prevhoff): the offset of "Next Header Field" in the header + * just before Fragment Header. + * (*fhoff) : the offset of Fragment Header. + * + * Based on ipv6_skip_hdr() in net/ipv6/exthdr.c + * + */ +static int +find_prev_fhdr(struct sk_buff *skb, u8 *prevhdrp, int *prevhoff, int *fhoff) +{ + u8 nexthdr = ipv6_hdr(skb)->nexthdr; + const int netoff = skb_network_offset(skb); + u8 prev_nhoff = netoff + offsetof(struct ipv6hdr, nexthdr); + int start = netoff + sizeof(struct ipv6hdr); + int len = skb->len - start; + u8 prevhdr = NEXTHDR_IPV6; + + while (nexthdr != NEXTHDR_FRAGMENT) { + struct ipv6_opt_hdr hdr; + int hdrlen; + + if (!ipv6_ext_hdr(nexthdr)) { + return -1; + } + if (nexthdr == NEXTHDR_NONE) { + pr_debug("next header is none\n"); + return -1; + } + if (len < (int)sizeof(struct ipv6_opt_hdr)) { + pr_debug("too short\n"); + return -1; + } + if (skb_copy_bits(skb, start, &hdr, sizeof(hdr))) + BUG(); + if (nexthdr == NEXTHDR_AUTH) + hdrlen = ipv6_authlen(&hdr); + else + hdrlen = ipv6_optlen(&hdr); + + prevhdr = nexthdr; + prev_nhoff = start; + + nexthdr = hdr.nexthdr; + len -= hdrlen; + start += hdrlen; + } + + if (len < 0) + return -1; + + *prevhdrp = prevhdr; + *prevhoff = prev_nhoff; + *fhoff = start; + + return 0; +} + +int nf_ct_frag6_gather(struct net *net, struct sk_buff *skb, u32 user) +{ + u16 savethdr = skb->transport_header; + u8 nexthdr = NEXTHDR_FRAGMENT; + int fhoff, nhoff, ret; + struct frag_hdr *fhdr; + struct frag_queue *fq; + struct ipv6hdr *hdr; + u8 prevhdr; + + /* Jumbo payload inhibits frag. header */ + if (ipv6_hdr(skb)->payload_len == 0) { + pr_debug("payload len = 0\n"); + return 0; + } + + if (find_prev_fhdr(skb, &prevhdr, &nhoff, &fhoff) < 0) + return 0; + + /* Discard the first fragment if it does not include all headers + * RFC 8200, Section 4.5 + */ + if (ipv6frag_thdr_truncated(skb, fhoff, &nexthdr)) { + pr_debug("Drop incomplete fragment\n"); + return 0; + } + + if (!pskb_may_pull(skb, fhoff + sizeof(*fhdr))) + return -ENOMEM; + + skb_set_transport_header(skb, fhoff); + hdr = ipv6_hdr(skb); + fhdr = (struct frag_hdr *)skb_transport_header(skb); + + skb_orphan(skb); + fq = fq_find(net, fhdr->identification, user, hdr, + skb->dev ? skb->dev->ifindex : 0); + if (fq == NULL) { + pr_debug("Can't find and can't create new queue\n"); + return -ENOMEM; + } + + spin_lock_bh(&fq->q.lock); + + ret = nf_ct_frag6_queue(fq, skb, fhdr, nhoff); + if (ret == -EPROTO) { + skb->transport_header = savethdr; + ret = 0; + } + + spin_unlock_bh(&fq->q.lock); + inet_frag_put(&fq->q); + return ret; +} +EXPORT_SYMBOL_GPL(nf_ct_frag6_gather); + +static int nf_ct_net_init(struct net *net) +{ + struct nft_ct_frag6_pernet *nf_frag = nf_frag_pernet(net); + int res; + + res = fqdir_init(&nf_frag->fqdir, &nf_frags, net); + if (res < 0) + return res; + + nf_frag->fqdir->high_thresh = IPV6_FRAG_HIGH_THRESH; + nf_frag->fqdir->low_thresh = IPV6_FRAG_LOW_THRESH; + nf_frag->fqdir->timeout = IPV6_FRAG_TIMEOUT; + + res = nf_ct_frag6_sysctl_register(net); + if (res < 0) + fqdir_exit(nf_frag->fqdir); + return res; +} + +static void nf_ct_net_pre_exit(struct net *net) +{ + struct nft_ct_frag6_pernet *nf_frag = nf_frag_pernet(net); + + fqdir_pre_exit(nf_frag->fqdir); +} + +static void nf_ct_net_exit(struct net *net) +{ + struct nft_ct_frag6_pernet *nf_frag = nf_frag_pernet(net); + + nf_ct_frags6_sysctl_unregister(net); + fqdir_exit(nf_frag->fqdir); +} + +static struct pernet_operations nf_ct_net_ops = { + .init = nf_ct_net_init, + .pre_exit = nf_ct_net_pre_exit, + .exit = nf_ct_net_exit, + .id = &nf_frag_pernet_id, + .size = sizeof(struct nft_ct_frag6_pernet), +}; + +static const struct rhashtable_params nfct_rhash_params = { + .head_offset = offsetof(struct inet_frag_queue, node), + .hashfn = ip6frag_key_hashfn, + .obj_hashfn = ip6frag_obj_hashfn, + .obj_cmpfn = ip6frag_obj_cmpfn, + .automatic_shrinking = true, +}; + +int nf_ct_frag6_init(void) +{ + int ret = 0; + + nf_frags.constructor = ip6frag_init; + nf_frags.destructor = NULL; + nf_frags.qsize = sizeof(struct frag_queue); + nf_frags.frag_expire = nf_ct_frag6_expire; + nf_frags.frags_cache_name = nf_frags_cache_name; + nf_frags.rhash_params = nfct_rhash_params; + ret = inet_frags_init(&nf_frags); + if (ret) + goto out; + ret = register_pernet_subsys(&nf_ct_net_ops); + if (ret) + inet_frags_fini(&nf_frags); + +out: + return ret; +} + +void nf_ct_frag6_cleanup(void) +{ + unregister_pernet_subsys(&nf_ct_net_ops); + inet_frags_fini(&nf_frags); +} |