diff options
Diffstat (limited to 'net/ieee802154/6lowpan/reassembly.c')
| -rw-r--r-- | net/ieee802154/6lowpan/reassembly.c | 635 |
1 files changed, 635 insertions, 0 deletions
diff --git a/net/ieee802154/6lowpan/reassembly.c b/net/ieee802154/6lowpan/reassembly.c new file mode 100644 index 000000000..f3074249c --- /dev/null +++ b/net/ieee802154/6lowpan/reassembly.c @@ -0,0 +1,635 @@ +/* 6LoWPAN fragment reassembly + * + * + * Authors: + * Alexander Aring <aar@pengutronix.de> + * + * Based on: net/ipv6/reassembly.c + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation; either version + * 2 of the License, or (at your option) any later version. + */ + +#define pr_fmt(fmt) "6LoWPAN: " fmt + +#include <linux/net.h> +#include <linux/list.h> +#include <linux/netdevice.h> +#include <linux/random.h> +#include <linux/jhash.h> +#include <linux/skbuff.h> +#include <linux/slab.h> +#include <linux/export.h> + +#include <net/ieee802154_netdev.h> +#include <net/6lowpan.h> +#include <net/ipv6_frag.h> +#include <net/inet_frag.h> + +#include "6lowpan_i.h" + +static const char lowpan_frags_cache_name[] = "lowpan-frags"; + +static struct inet_frags lowpan_frags; + +static int lowpan_frag_reasm(struct lowpan_frag_queue *fq, + struct sk_buff *prev, struct net_device *ldev); + +static void lowpan_frag_init(struct inet_frag_queue *q, const void *a) +{ + const struct frag_lowpan_compare_key *key = a; + + BUILD_BUG_ON(sizeof(*key) > sizeof(q->key)); + memcpy(&q->key, key, sizeof(*key)); +} + +static void lowpan_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); + + spin_lock(&fq->q.lock); + + if (fq->q.flags & INET_FRAG_COMPLETE) + goto out; + + inet_frag_kill(&fq->q); +out: + spin_unlock(&fq->q.lock); + inet_frag_put(&fq->q); +} + +static inline struct lowpan_frag_queue * +fq_find(struct net *net, const struct lowpan_802154_cb *cb, + const struct ieee802154_addr *src, + const struct ieee802154_addr *dst) +{ + struct netns_ieee802154_lowpan *ieee802154_lowpan = + net_ieee802154_lowpan(net); + struct frag_lowpan_compare_key key = {}; + struct inet_frag_queue *q; + + key.tag = cb->d_tag; + key.d_size = cb->d_size; + key.src = *src; + key.dst = *dst; + + q = inet_frag_find(&ieee802154_lowpan->frags, &key); + if (!q) + return NULL; + + return container_of(q, struct lowpan_frag_queue, q); +} + +static int lowpan_frag_queue(struct lowpan_frag_queue *fq, + struct sk_buff *skb, u8 frag_type) +{ + struct sk_buff *prev, *next; + struct net_device *ldev; + int end, offset; + + if (fq->q.flags & INET_FRAG_COMPLETE) + goto err; + + offset = lowpan_802154_cb(skb)->d_offset << 3; + end = lowpan_802154_cb(skb)->d_size; + + /* Is this the final fragment? */ + if (offset + skb->len == end) { + /* 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 err; + fq->q.flags |= INET_FRAG_LAST_IN; + fq->q.len = end; + } else { + if (end > fq->q.len) { + /* Some bits beyond end -> corruption. */ + if (fq->q.flags & INET_FRAG_LAST_IN) + goto err; + fq->q.len = end; + } + } + + /* Find out which fragments are in front and at the back of us + * in the chain of fragments so far. We must know where to put + * this fragment, right? + */ + prev = fq->q.fragments_tail; + if (!prev || + lowpan_802154_cb(prev)->d_offset < + lowpan_802154_cb(skb)->d_offset) { + next = NULL; + goto found; + } + prev = NULL; + for (next = fq->q.fragments; next != NULL; next = next->next) { + if (lowpan_802154_cb(next)->d_offset >= + lowpan_802154_cb(skb)->d_offset) + break; /* bingo! */ + prev = next; + } + +found: + /* Insert this fragment in the chain of fragments. */ + skb->next = next; + if (!next) + fq->q.fragments_tail = skb; + if (prev) + prev->next = skb; + else + fq->q.fragments = skb; + + ldev = skb->dev; + if (ldev) + skb->dev = NULL; + + fq->q.stamp = skb->tstamp; + if (frag_type == LOWPAN_DISPATCH_FRAG1) + fq->q.flags |= INET_FRAG_FIRST_IN; + + fq->q.meat += skb->len; + add_frag_mem_limit(fq->q.net, skb->truesize); + + if (fq->q.flags == (INET_FRAG_FIRST_IN | INET_FRAG_LAST_IN) && + fq->q.meat == fq->q.len) { + int res; + unsigned long orefdst = skb->_skb_refdst; + + skb->_skb_refdst = 0UL; + res = lowpan_frag_reasm(fq, prev, ldev); + skb->_skb_refdst = orefdst; + return res; + } + + return -1; +err: + kfree_skb(skb); + return -1; +} + +/* Check if this packet is complete. + * Returns NULL on failure by any reason, and pointer + * to current nexthdr field in reassembled frame. + * + * 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 lowpan_frag_reasm(struct lowpan_frag_queue *fq, struct sk_buff *prev, + struct net_device *ldev) +{ + struct sk_buff *fp, *head = fq->q.fragments; + int sum_truesize; + + inet_frag_kill(&fq->q); + + /* Make the one we just received the head. */ + if (prev) { + head = prev->next; + fp = skb_clone(head, GFP_ATOMIC); + + if (!fp) + goto out_oom; + + fp->next = head->next; + if (!fp->next) + fq->q.fragments_tail = fp; + prev->next = fp; + + skb_morph(head, fq->q.fragments); + head->next = fq->q.fragments->next; + + consume_skb(fq->q.fragments); + fq->q.fragments = head; + } + + /* Head of list must not be cloned. */ + if (skb_unclone(head, GFP_ATOMIC)) + goto out_oom; + + /* If the first fragment is fragmented itself, we split + * it to two chunks: the first with data and paged part + * and the second, holding only fragments. + */ + if (skb_has_frag_list(head)) { + struct sk_buff *clone; + int i, plen = 0; + + clone = alloc_skb(0, GFP_ATOMIC); + if (!clone) + goto out_oom; + clone->next = head->next; + head->next = clone; + skb_shinfo(clone)->frag_list = skb_shinfo(head)->frag_list; + skb_frag_list_init(head); + for (i = 0; i < skb_shinfo(head)->nr_frags; i++) + plen += skb_frag_size(&skb_shinfo(head)->frags[i]); + clone->len = head->data_len - plen; + clone->data_len = clone->len; + head->data_len -= clone->len; + head->len -= clone->len; + add_frag_mem_limit(fq->q.net, clone->truesize); + } + + WARN_ON(head == NULL); + + sum_truesize = head->truesize; + for (fp = head->next; fp;) { + bool headstolen; + int delta; + struct sk_buff *next = fp->next; + + sum_truesize += fp->truesize; + if (skb_try_coalesce(head, fp, &headstolen, &delta)) { + kfree_skb_partial(fp, headstolen); + } else { + if (!skb_shinfo(head)->frag_list) + skb_shinfo(head)->frag_list = fp; + head->data_len += fp->len; + head->len += fp->len; + head->truesize += fp->truesize; + } + fp = next; + } + sub_frag_mem_limit(fq->q.net, sum_truesize); + + head->next = NULL; + head->dev = ldev; + head->tstamp = fq->q.stamp; + + fq->q.fragments = NULL; + fq->q.fragments_tail = NULL; + + return 1; +out_oom: + net_dbg_ratelimited("lowpan_frag_reasm: no memory for reassembly\n"); + return -1; +} + +static int lowpan_frag_rx_handlers_result(struct sk_buff *skb, + lowpan_rx_result res) +{ + switch (res) { + case RX_QUEUED: + return NET_RX_SUCCESS; + case RX_CONTINUE: + /* nobody cared about this packet */ + net_warn_ratelimited("%s: received unknown dispatch\n", + __func__); + + /* fall-through */ + default: + /* all others failure */ + return NET_RX_DROP; + } +} + +static lowpan_rx_result lowpan_frag_rx_h_iphc(struct sk_buff *skb) +{ + int ret; + + if (!lowpan_is_iphc(*skb_network_header(skb))) + return RX_CONTINUE; + + ret = lowpan_iphc_decompress(skb); + if (ret < 0) + return RX_DROP; + + return RX_QUEUED; +} + +static int lowpan_invoke_frag_rx_handlers(struct sk_buff *skb) +{ + lowpan_rx_result res; + +#define CALL_RXH(rxh) \ + do { \ + res = rxh(skb); \ + if (res != RX_CONTINUE) \ + goto rxh_next; \ + } while (0) + + /* likely at first */ + CALL_RXH(lowpan_frag_rx_h_iphc); + CALL_RXH(lowpan_rx_h_ipv6); + +rxh_next: + return lowpan_frag_rx_handlers_result(skb, res); +#undef CALL_RXH +} + +#define LOWPAN_FRAG_DGRAM_SIZE_HIGH_MASK 0x07 +#define LOWPAN_FRAG_DGRAM_SIZE_HIGH_SHIFT 8 + +static int lowpan_get_cb(struct sk_buff *skb, u8 frag_type, + struct lowpan_802154_cb *cb) +{ + bool fail; + u8 high = 0, low = 0; + __be16 d_tag = 0; + + fail = lowpan_fetch_skb(skb, &high, 1); + fail |= lowpan_fetch_skb(skb, &low, 1); + /* remove the dispatch value and use first three bits as high value + * for the datagram size + */ + cb->d_size = (high & LOWPAN_FRAG_DGRAM_SIZE_HIGH_MASK) << + LOWPAN_FRAG_DGRAM_SIZE_HIGH_SHIFT | low; + fail |= lowpan_fetch_skb(skb, &d_tag, 2); + cb->d_tag = ntohs(d_tag); + + if (frag_type == LOWPAN_DISPATCH_FRAGN) { + fail |= lowpan_fetch_skb(skb, &cb->d_offset, 1); + } else { + skb_reset_network_header(skb); + cb->d_offset = 0; + /* check if datagram_size has ipv6hdr on FRAG1 */ + fail |= cb->d_size < sizeof(struct ipv6hdr); + /* check if we can dereference the dispatch value */ + fail |= !skb->len; + } + + if (unlikely(fail)) + return -EIO; + + return 0; +} + +int lowpan_frag_rcv(struct sk_buff *skb, u8 frag_type) +{ + struct lowpan_frag_queue *fq; + struct net *net = dev_net(skb->dev); + struct lowpan_802154_cb *cb = lowpan_802154_cb(skb); + struct ieee802154_hdr hdr = {}; + int err; + + if (ieee802154_hdr_peek_addrs(skb, &hdr) < 0) + goto err; + + err = lowpan_get_cb(skb, frag_type, cb); + if (err < 0) + goto err; + + if (frag_type == LOWPAN_DISPATCH_FRAG1) { + err = lowpan_invoke_frag_rx_handlers(skb); + if (err == NET_RX_DROP) + goto err; + } + + if (cb->d_size > IPV6_MIN_MTU) { + net_warn_ratelimited("lowpan_frag_rcv: datagram size exceeds MTU\n"); + goto err; + } + + fq = fq_find(net, cb, &hdr.source, &hdr.dest); + if (fq != NULL) { + int ret; + + spin_lock(&fq->q.lock); + ret = lowpan_frag_queue(fq, skb, frag_type); + spin_unlock(&fq->q.lock); + + inet_frag_put(&fq->q); + return ret; + } + +err: + kfree_skb(skb); + return -1; +} + +#ifdef CONFIG_SYSCTL + +static struct ctl_table lowpan_frags_ns_ctl_table[] = { + { + .procname = "6lowpanfrag_high_thresh", + .data = &init_net.ieee802154_lowpan.frags.high_thresh, + .maxlen = sizeof(unsigned long), + .mode = 0644, + .proc_handler = proc_doulongvec_minmax, + .extra1 = &init_net.ieee802154_lowpan.frags.low_thresh + }, + { + .procname = "6lowpanfrag_low_thresh", + .data = &init_net.ieee802154_lowpan.frags.low_thresh, + .maxlen = sizeof(unsigned long), + .mode = 0644, + .proc_handler = proc_doulongvec_minmax, + .extra2 = &init_net.ieee802154_lowpan.frags.high_thresh + }, + { + .procname = "6lowpanfrag_time", + .data = &init_net.ieee802154_lowpan.frags.timeout, + .maxlen = sizeof(int), + .mode = 0644, + .proc_handler = proc_dointvec_jiffies, + }, + { } +}; + +/* secret interval has been deprecated */ +static int lowpan_frags_secret_interval_unused; +static struct ctl_table lowpan_frags_ctl_table[] = { + { + .procname = "6lowpanfrag_secret_interval", + .data = &lowpan_frags_secret_interval_unused, + .maxlen = sizeof(int), + .mode = 0644, + .proc_handler = proc_dointvec_jiffies, + }, + { } +}; + +static int __net_init lowpan_frags_ns_sysctl_register(struct net *net) +{ + struct ctl_table *table; + struct ctl_table_header *hdr; + struct netns_ieee802154_lowpan *ieee802154_lowpan = + net_ieee802154_lowpan(net); + + table = lowpan_frags_ns_ctl_table; + if (!net_eq(net, &init_net)) { + table = kmemdup(table, sizeof(lowpan_frags_ns_ctl_table), + GFP_KERNEL); + if (table == NULL) + goto err_alloc; + + table[0].data = &ieee802154_lowpan->frags.high_thresh; + table[0].extra1 = &ieee802154_lowpan->frags.low_thresh; + table[0].extra2 = &init_net.ieee802154_lowpan.frags.high_thresh; + table[1].data = &ieee802154_lowpan->frags.low_thresh; + table[1].extra2 = &ieee802154_lowpan->frags.high_thresh; + table[2].data = &ieee802154_lowpan->frags.timeout; + + /* Don't export sysctls to unprivileged users */ + if (net->user_ns != &init_user_ns) + table[0].procname = NULL; + } + + hdr = register_net_sysctl(net, "net/ieee802154/6lowpan", table); + if (hdr == NULL) + goto err_reg; + + ieee802154_lowpan->sysctl.frags_hdr = hdr; + return 0; + +err_reg: + if (!net_eq(net, &init_net)) + kfree(table); +err_alloc: + return -ENOMEM; +} + +static void __net_exit lowpan_frags_ns_sysctl_unregister(struct net *net) +{ + struct ctl_table *table; + struct netns_ieee802154_lowpan *ieee802154_lowpan = + net_ieee802154_lowpan(net); + + table = ieee802154_lowpan->sysctl.frags_hdr->ctl_table_arg; + unregister_net_sysctl_table(ieee802154_lowpan->sysctl.frags_hdr); + if (!net_eq(net, &init_net)) + kfree(table); +} + +static struct ctl_table_header *lowpan_ctl_header; + +static int __init lowpan_frags_sysctl_register(void) +{ + lowpan_ctl_header = register_net_sysctl(&init_net, + "net/ieee802154/6lowpan", + lowpan_frags_ctl_table); + return lowpan_ctl_header == NULL ? -ENOMEM : 0; +} + +static void lowpan_frags_sysctl_unregister(void) +{ + unregister_net_sysctl_table(lowpan_ctl_header); +} +#else +static inline int lowpan_frags_ns_sysctl_register(struct net *net) +{ + return 0; +} + +static inline void lowpan_frags_ns_sysctl_unregister(struct net *net) +{ +} + +static inline int __init lowpan_frags_sysctl_register(void) +{ + return 0; +} + +static inline void lowpan_frags_sysctl_unregister(void) +{ +} +#endif + +static int __net_init lowpan_frags_init_net(struct net *net) +{ + struct netns_ieee802154_lowpan *ieee802154_lowpan = + net_ieee802154_lowpan(net); + int res; + + ieee802154_lowpan->frags.high_thresh = IPV6_FRAG_HIGH_THRESH; + ieee802154_lowpan->frags.low_thresh = IPV6_FRAG_LOW_THRESH; + ieee802154_lowpan->frags.timeout = IPV6_FRAG_TIMEOUT; + ieee802154_lowpan->frags.f = &lowpan_frags; + + res = inet_frags_init_net(&ieee802154_lowpan->frags); + if (res < 0) + return res; + res = lowpan_frags_ns_sysctl_register(net); + if (res < 0) + inet_frags_exit_net(&ieee802154_lowpan->frags); + return res; +} + +static void __net_exit lowpan_frags_exit_net(struct net *net) +{ + struct netns_ieee802154_lowpan *ieee802154_lowpan = + net_ieee802154_lowpan(net); + + lowpan_frags_ns_sysctl_unregister(net); + inet_frags_exit_net(&ieee802154_lowpan->frags); +} + +static struct pernet_operations lowpan_frags_ops = { + .init = lowpan_frags_init_net, + .exit = lowpan_frags_exit_net, +}; + +static u32 lowpan_key_hashfn(const void *data, u32 len, u32 seed) +{ + return jhash2(data, + sizeof(struct frag_lowpan_compare_key) / sizeof(u32), seed); +} + +static u32 lowpan_obj_hashfn(const void *data, u32 len, u32 seed) +{ + const struct inet_frag_queue *fq = data; + + return jhash2((const u32 *)&fq->key, + sizeof(struct frag_lowpan_compare_key) / sizeof(u32), seed); +} + +static int lowpan_obj_cmpfn(struct rhashtable_compare_arg *arg, const void *ptr) +{ + const struct frag_lowpan_compare_key *key = arg->key; + const struct inet_frag_queue *fq = ptr; + + return !!memcmp(&fq->key, key, sizeof(*key)); +} + +static const struct rhashtable_params lowpan_rhash_params = { + .head_offset = offsetof(struct inet_frag_queue, node), + .hashfn = lowpan_key_hashfn, + .obj_hashfn = lowpan_obj_hashfn, + .obj_cmpfn = lowpan_obj_cmpfn, + .automatic_shrinking = true, +}; + +int __init lowpan_net_frag_init(void) +{ + int ret; + + lowpan_frags.constructor = lowpan_frag_init; + lowpan_frags.destructor = NULL; + lowpan_frags.qsize = sizeof(struct frag_queue); + lowpan_frags.frag_expire = lowpan_frag_expire; + lowpan_frags.frags_cache_name = lowpan_frags_cache_name; + lowpan_frags.rhash_params = lowpan_rhash_params; + ret = inet_frags_init(&lowpan_frags); + if (ret) + goto out; + + ret = lowpan_frags_sysctl_register(); + if (ret) + goto err_sysctl; + + ret = register_pernet_subsys(&lowpan_frags_ops); + if (ret) + goto err_pernet; +out: + return ret; +err_pernet: + lowpan_frags_sysctl_unregister(); +err_sysctl: + inet_frags_fini(&lowpan_frags); + return ret; +} + +void lowpan_net_frag_exit(void) +{ + lowpan_frags_sysctl_unregister(); + unregister_pernet_subsys(&lowpan_frags_ops); + inet_frags_fini(&lowpan_frags); +} |