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-rw-r--r--net/ipv6/reassembly.c618
1 files changed, 618 insertions, 0 deletions
diff --git a/net/ipv6/reassembly.c b/net/ipv6/reassembly.c
new file mode 100644
index 0000000000..5ebc47da10
--- /dev/null
+++ b/net/ipv6/reassembly.c
@@ -0,0 +1,618 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * IPv6 fragment reassembly
+ * Linux INET6 implementation
+ *
+ * Authors:
+ * Pedro Roque <roque@di.fc.ul.pt>
+ *
+ * Based on: net/ipv4/ip_fragment.c
+ */
+
+/*
+ * Fixes:
+ * Andi Kleen Make it work with multiple hosts.
+ * More RFC compliance.
+ *
+ * Horst von Brand Add missing #include <linux/string.h>
+ * Alexey Kuznetsov SMP races, threading, cleanup.
+ * Patrick McHardy LRU queue of frag heads for evictor.
+ * Mitsuru KANDA @USAGI Register inet6_protocol{}.
+ * David Stevens and
+ * YOSHIFUJI,H. @USAGI Always remove fragment header to
+ * calculate ICV correctly.
+ */
+
+#define pr_fmt(fmt) "IPv6: " fmt
+
+#include <linux/errno.h>
+#include <linux/types.h>
+#include <linux/string.h>
+#include <linux/socket.h>
+#include <linux/sockios.h>
+#include <linux/jiffies.h>
+#include <linux/net.h>
+#include <linux/list.h>
+#include <linux/netdevice.h>
+#include <linux/in6.h>
+#include <linux/ipv6.h>
+#include <linux/icmpv6.h>
+#include <linux/random.h>
+#include <linux/jhash.h>
+#include <linux/skbuff.h>
+#include <linux/slab.h>
+#include <linux/export.h>
+#include <linux/tcp.h>
+#include <linux/udp.h>
+
+#include <net/sock.h>
+#include <net/snmp.h>
+
+#include <net/ipv6.h>
+#include <net/ip6_route.h>
+#include <net/protocol.h>
+#include <net/transp_v6.h>
+#include <net/rawv6.h>
+#include <net/ndisc.h>
+#include <net/addrconf.h>
+#include <net/ipv6_frag.h>
+#include <net/inet_ecn.h>
+
+static const char ip6_frag_cache_name[] = "ip6-frags";
+
+static u8 ip6_frag_ecn(const struct ipv6hdr *ipv6h)
+{
+ return 1 << (ipv6_get_dsfield(ipv6h) & INET_ECN_MASK);
+}
+
+static struct inet_frags ip6_frags;
+
+static int ip6_frag_reasm(struct frag_queue *fq, struct sk_buff *skb,
+ struct sk_buff *prev_tail, struct net_device *dev);
+
+static void ip6_frag_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);
+}
+
+static struct frag_queue *
+fq_find(struct net *net, __be32 id, const struct ipv6hdr *hdr, int iif)
+{
+ struct frag_v6_compare_key key = {
+ .id = id,
+ .saddr = hdr->saddr,
+ .daddr = hdr->daddr,
+ .user = IP6_DEFRAG_LOCAL_DELIVER,
+ .iif = iif,
+ };
+ struct inet_frag_queue *q;
+
+ if (!(ipv6_addr_type(&hdr->daddr) & (IPV6_ADDR_MULTICAST |
+ IPV6_ADDR_LINKLOCAL)))
+ key.iif = 0;
+
+ q = inet_frag_find(net->ipv6.fqdir, &key);
+ if (!q)
+ return NULL;
+
+ return container_of(q, struct frag_queue, q);
+}
+
+static int ip6_frag_queue(struct frag_queue *fq, struct sk_buff *skb,
+ struct frag_hdr *fhdr, int nhoff,
+ u32 *prob_offset)
+{
+ struct net *net = dev_net(skb_dst(skb)->dev);
+ int offset, end, fragsize;
+ struct sk_buff *prev_tail;
+ struct net_device *dev;
+ int err = -ENOENT;
+ SKB_DR(reason);
+ u8 ecn;
+
+ /* If reassembly is already done, @skb must be a duplicate frag. */
+ if (fq->q.flags & INET_FRAG_COMPLETE) {
+ SKB_DR_SET(reason, DUP_FRAG);
+ goto err;
+ }
+
+ err = -EINVAL;
+ offset = ntohs(fhdr->frag_off) & ~0x7;
+ end = offset + (ntohs(ipv6_hdr(skb)->payload_len) -
+ ((u8 *)(fhdr + 1) - (u8 *)(ipv6_hdr(skb) + 1)));
+
+ if ((unsigned int)end > IPV6_MAXPLEN) {
+ *prob_offset = (u8 *)&fhdr->frag_off - skb_network_header(skb);
+ /* note that if prob_offset is set, the skb is freed elsewhere,
+ * we do not free it here.
+ */
+ return -1;
+ }
+
+ 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))
+ goto discard_fq;
+ 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
+ */
+ *prob_offset = offsetof(struct ipv6hdr, payload_len);
+ return -1;
+ }
+ if (end > fq->q.len) {
+ /* Some bits beyond end -> corruption. */
+ if (fq->q.flags & INET_FRAG_LAST_IN)
+ goto discard_fq;
+ fq->q.len = end;
+ }
+ }
+
+ if (end == offset)
+ goto discard_fq;
+
+ err = -ENOMEM;
+ /* Point into the IP datagram 'data' part. */
+ if (!pskb_pull(skb, (u8 *) (fhdr + 1) - skb->data))
+ goto discard_fq;
+
+ err = pskb_trim_rcsum(skb, end - offset);
+ if (err)
+ goto discard_fq;
+
+ /* Note : skb->rbnode and skb->dev share the same location. */
+ dev = skb->dev;
+ /* Makes sure compiler wont do silly aliasing games */
+ barrier();
+
+ prev_tail = fq->q.fragments_tail;
+ err = inet_frag_queue_insert(&fq->q, skb, offset, end);
+ if (err)
+ 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;
+ add_frag_mem_limit(fq->q.fqdir, skb->truesize);
+
+ fragsize = -skb_network_offset(skb) + skb->len;
+ if (fragsize > fq->q.max_size)
+ fq->q.max_size = fragsize;
+
+ /* 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 = ip6_frag_reasm(fq, skb, prev_tail, dev);
+ skb->_skb_refdst = orefdst;
+ return err;
+ }
+
+ skb_dst_drop(skb);
+ return -EINPROGRESS;
+
+insert_error:
+ if (err == IPFRAG_DUP) {
+ SKB_DR_SET(reason, DUP_FRAG);
+ err = -EINVAL;
+ goto err;
+ }
+ err = -EINVAL;
+ __IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)),
+ IPSTATS_MIB_REASM_OVERLAPS);
+discard_fq:
+ inet_frag_kill(&fq->q);
+ __IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)),
+ IPSTATS_MIB_REASMFAILS);
+err:
+ kfree_skb_reason(skb, reason);
+ return err;
+}
+
+/*
+ * 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 ip6_frag_reasm(struct frag_queue *fq, struct sk_buff *skb,
+ struct sk_buff *prev_tail, struct net_device *dev)
+{
+ struct net *net = fq->q.fqdir->net;
+ unsigned int nhoff;
+ 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 out_fail;
+
+ reasm_data = inet_frag_reasm_prepare(&fq->q, skb, prev_tail);
+ if (!reasm_data)
+ goto out_oom;
+
+ payload_len = ((skb->data - skb_network_header(skb)) -
+ sizeof(struct ipv6hdr) + fq->q.len -
+ sizeof(struct frag_hdr));
+ if (payload_len > IPV6_MAXPLEN)
+ goto out_oversize;
+
+ /* We have to remove fragment header from datagram and to relocate
+ * header in order to calculate ICV correctly. */
+ nhoff = fq->nhoffset;
+ skb_network_header(skb)[nhoff] = skb_transport_header(skb)[0];
+ memmove(skb->head + sizeof(struct frag_hdr), skb->head,
+ (skb->data - skb->head) - sizeof(struct frag_hdr));
+ if (skb_mac_header_was_set(skb))
+ 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, true);
+
+ skb->dev = dev;
+ ipv6_hdr(skb)->payload_len = htons(payload_len);
+ ipv6_change_dsfield(ipv6_hdr(skb), 0xff, ecn);
+ IP6CB(skb)->nhoff = nhoff;
+ IP6CB(skb)->flags |= IP6SKB_FRAGMENTED;
+ IP6CB(skb)->frag_max_size = fq->q.max_size;
+
+ /* Yes, and fold redundant checksum back. 8) */
+ skb_postpush_rcsum(skb, skb_network_header(skb),
+ skb_network_header_len(skb));
+
+ rcu_read_lock();
+ __IP6_INC_STATS(net, __in6_dev_stats_get(dev, skb), IPSTATS_MIB_REASMOKS);
+ rcu_read_unlock();
+ fq->q.rb_fragments = RB_ROOT;
+ fq->q.fragments_tail = NULL;
+ fq->q.last_run_head = NULL;
+ return 1;
+
+out_oversize:
+ net_dbg_ratelimited("ip6_frag_reasm: payload len = %d\n", payload_len);
+ goto out_fail;
+out_oom:
+ net_dbg_ratelimited("ip6_frag_reasm: no memory for reassembly\n");
+out_fail:
+ rcu_read_lock();
+ __IP6_INC_STATS(net, __in6_dev_stats_get(dev, skb), IPSTATS_MIB_REASMFAILS);
+ rcu_read_unlock();
+ inet_frag_kill(&fq->q);
+ return -1;
+}
+
+static int ipv6_frag_rcv(struct sk_buff *skb)
+{
+ struct frag_hdr *fhdr;
+ struct frag_queue *fq;
+ const struct ipv6hdr *hdr = ipv6_hdr(skb);
+ struct net *net = dev_net(skb_dst(skb)->dev);
+ u8 nexthdr;
+ int iif;
+
+ if (IP6CB(skb)->flags & IP6SKB_FRAGMENTED)
+ goto fail_hdr;
+
+ __IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)), IPSTATS_MIB_REASMREQDS);
+
+ /* Jumbo payload inhibits frag. header */
+ if (hdr->payload_len == 0)
+ goto fail_hdr;
+
+ if (!pskb_may_pull(skb, (skb_transport_offset(skb) +
+ sizeof(struct frag_hdr))))
+ goto fail_hdr;
+
+ hdr = ipv6_hdr(skb);
+ fhdr = (struct frag_hdr *)skb_transport_header(skb);
+
+ if (!(fhdr->frag_off & htons(IP6_OFFSET | IP6_MF))) {
+ /* It is not a fragmented frame */
+ skb->transport_header += sizeof(struct frag_hdr);
+ __IP6_INC_STATS(net,
+ ip6_dst_idev(skb_dst(skb)), IPSTATS_MIB_REASMOKS);
+
+ IP6CB(skb)->nhoff = (u8 *)fhdr - skb_network_header(skb);
+ IP6CB(skb)->flags |= IP6SKB_FRAGMENTED;
+ IP6CB(skb)->frag_max_size = ntohs(hdr->payload_len) +
+ sizeof(struct ipv6hdr);
+ return 1;
+ }
+
+ /* RFC 8200, Section 4.5 Fragment Header:
+ * If the first fragment does not include all headers through an
+ * Upper-Layer header, then that fragment should be discarded and
+ * an ICMP Parameter Problem, Code 3, message should be sent to
+ * the source of the fragment, with the Pointer field set to zero.
+ */
+ nexthdr = hdr->nexthdr;
+ if (ipv6frag_thdr_truncated(skb, skb_transport_offset(skb), &nexthdr)) {
+ __IP6_INC_STATS(net, __in6_dev_get_safely(skb->dev),
+ IPSTATS_MIB_INHDRERRORS);
+ icmpv6_param_prob(skb, ICMPV6_HDR_INCOMP, 0);
+ return -1;
+ }
+
+ iif = skb->dev ? skb->dev->ifindex : 0;
+ fq = fq_find(net, fhdr->identification, hdr, iif);
+ if (fq) {
+ u32 prob_offset = 0;
+ int ret;
+
+ spin_lock(&fq->q.lock);
+
+ fq->iif = iif;
+ ret = ip6_frag_queue(fq, skb, fhdr, IP6CB(skb)->nhoff,
+ &prob_offset);
+
+ spin_unlock(&fq->q.lock);
+ inet_frag_put(&fq->q);
+ if (prob_offset) {
+ __IP6_INC_STATS(net, __in6_dev_get_safely(skb->dev),
+ IPSTATS_MIB_INHDRERRORS);
+ /* icmpv6_param_prob() calls kfree_skb(skb) */
+ icmpv6_param_prob(skb, ICMPV6_HDR_FIELD, prob_offset);
+ }
+ return ret;
+ }
+
+ __IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)), IPSTATS_MIB_REASMFAILS);
+ kfree_skb(skb);
+ return -1;
+
+fail_hdr:
+ __IP6_INC_STATS(net, __in6_dev_get_safely(skb->dev),
+ IPSTATS_MIB_INHDRERRORS);
+ icmpv6_param_prob(skb, ICMPV6_HDR_FIELD, skb_network_header_len(skb));
+ return -1;
+}
+
+static const struct inet6_protocol frag_protocol = {
+ .handler = ipv6_frag_rcv,
+ .flags = INET6_PROTO_NOPOLICY,
+};
+
+#ifdef CONFIG_SYSCTL
+
+static struct ctl_table ip6_frags_ns_ctl_table[] = {
+ {
+ .procname = "ip6frag_high_thresh",
+ .maxlen = sizeof(unsigned long),
+ .mode = 0644,
+ .proc_handler = proc_doulongvec_minmax,
+ },
+ {
+ .procname = "ip6frag_low_thresh",
+ .maxlen = sizeof(unsigned long),
+ .mode = 0644,
+ .proc_handler = proc_doulongvec_minmax,
+ },
+ {
+ .procname = "ip6frag_time",
+ .maxlen = sizeof(int),
+ .mode = 0644,
+ .proc_handler = proc_dointvec_jiffies,
+ },
+ { }
+};
+
+/* secret interval has been deprecated */
+static int ip6_frags_secret_interval_unused;
+static struct ctl_table ip6_frags_ctl_table[] = {
+ {
+ .procname = "ip6frag_secret_interval",
+ .data = &ip6_frags_secret_interval_unused,
+ .maxlen = sizeof(int),
+ .mode = 0644,
+ .proc_handler = proc_dointvec_jiffies,
+ },
+ { }
+};
+
+static int __net_init ip6_frags_ns_sysctl_register(struct net *net)
+{
+ struct ctl_table *table;
+ struct ctl_table_header *hdr;
+
+ table = ip6_frags_ns_ctl_table;
+ if (!net_eq(net, &init_net)) {
+ table = kmemdup(table, sizeof(ip6_frags_ns_ctl_table), GFP_KERNEL);
+ if (!table)
+ goto err_alloc;
+
+ }
+ table[0].data = &net->ipv6.fqdir->high_thresh;
+ table[0].extra1 = &net->ipv6.fqdir->low_thresh;
+ table[1].data = &net->ipv6.fqdir->low_thresh;
+ table[1].extra2 = &net->ipv6.fqdir->high_thresh;
+ table[2].data = &net->ipv6.fqdir->timeout;
+
+ hdr = register_net_sysctl_sz(net, "net/ipv6", table,
+ ARRAY_SIZE(ip6_frags_ns_ctl_table));
+ if (!hdr)
+ goto err_reg;
+
+ net->ipv6.sysctl.frags_hdr = hdr;
+ return 0;
+
+err_reg:
+ if (!net_eq(net, &init_net))
+ kfree(table);
+err_alloc:
+ return -ENOMEM;
+}
+
+static void __net_exit ip6_frags_ns_sysctl_unregister(struct net *net)
+{
+ struct ctl_table *table;
+
+ table = net->ipv6.sysctl.frags_hdr->ctl_table_arg;
+ unregister_net_sysctl_table(net->ipv6.sysctl.frags_hdr);
+ if (!net_eq(net, &init_net))
+ kfree(table);
+}
+
+static struct ctl_table_header *ip6_ctl_header;
+
+static int ip6_frags_sysctl_register(void)
+{
+ ip6_ctl_header = register_net_sysctl(&init_net, "net/ipv6",
+ ip6_frags_ctl_table);
+ return ip6_ctl_header == NULL ? -ENOMEM : 0;
+}
+
+static void ip6_frags_sysctl_unregister(void)
+{
+ unregister_net_sysctl_table(ip6_ctl_header);
+}
+#else
+static int ip6_frags_ns_sysctl_register(struct net *net)
+{
+ return 0;
+}
+
+static void ip6_frags_ns_sysctl_unregister(struct net *net)
+{
+}
+
+static int ip6_frags_sysctl_register(void)
+{
+ return 0;
+}
+
+static void ip6_frags_sysctl_unregister(void)
+{
+}
+#endif
+
+static int __net_init ipv6_frags_init_net(struct net *net)
+{
+ int res;
+
+ res = fqdir_init(&net->ipv6.fqdir, &ip6_frags, net);
+ if (res < 0)
+ return res;
+
+ net->ipv6.fqdir->high_thresh = IPV6_FRAG_HIGH_THRESH;
+ net->ipv6.fqdir->low_thresh = IPV6_FRAG_LOW_THRESH;
+ net->ipv6.fqdir->timeout = IPV6_FRAG_TIMEOUT;
+
+ res = ip6_frags_ns_sysctl_register(net);
+ if (res < 0)
+ fqdir_exit(net->ipv6.fqdir);
+ return res;
+}
+
+static void __net_exit ipv6_frags_pre_exit_net(struct net *net)
+{
+ fqdir_pre_exit(net->ipv6.fqdir);
+}
+
+static void __net_exit ipv6_frags_exit_net(struct net *net)
+{
+ ip6_frags_ns_sysctl_unregister(net);
+ fqdir_exit(net->ipv6.fqdir);
+}
+
+static struct pernet_operations ip6_frags_ops = {
+ .init = ipv6_frags_init_net,
+ .pre_exit = ipv6_frags_pre_exit_net,
+ .exit = ipv6_frags_exit_net,
+};
+
+static const struct rhashtable_params ip6_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 __init ipv6_frag_init(void)
+{
+ int ret;
+
+ ip6_frags.constructor = ip6frag_init;
+ ip6_frags.destructor = NULL;
+ ip6_frags.qsize = sizeof(struct frag_queue);
+ ip6_frags.frag_expire = ip6_frag_expire;
+ ip6_frags.frags_cache_name = ip6_frag_cache_name;
+ ip6_frags.rhash_params = ip6_rhash_params;
+ ret = inet_frags_init(&ip6_frags);
+ if (ret)
+ goto out;
+
+ ret = inet6_add_protocol(&frag_protocol, IPPROTO_FRAGMENT);
+ if (ret)
+ goto err_protocol;
+
+ ret = ip6_frags_sysctl_register();
+ if (ret)
+ goto err_sysctl;
+
+ ret = register_pernet_subsys(&ip6_frags_ops);
+ if (ret)
+ goto err_pernet;
+
+out:
+ return ret;
+
+err_pernet:
+ ip6_frags_sysctl_unregister();
+err_sysctl:
+ inet6_del_protocol(&frag_protocol, IPPROTO_FRAGMENT);
+err_protocol:
+ inet_frags_fini(&ip6_frags);
+ goto out;
+}
+
+void ipv6_frag_exit(void)
+{
+ ip6_frags_sysctl_unregister();
+ unregister_pernet_subsys(&ip6_frags_ops);
+ inet6_del_protocol(&frag_protocol, IPPROTO_FRAGMENT);
+ inet_frags_fini(&ip6_frags);
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-25 11:38:18 +0000