diff options
author | Alexander Aring <alex.aring@gmail.com> | 2014-02-28 07:32:50 +0100 |
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committer | David S. Miller <davem@davemloft.net> | 2014-02-28 17:05:22 -0500 |
commit | 7240cdec60b136f3e64a453c7fbded4ed1aa047e (patch) | |
tree | 1ef358c776a1493ba1d2e6786bf070b05e960c48 /net/ieee802154/reassembly.c | |
parent | 633fc86ff621bba79dcddfd4c67fb07ae5f8467c (diff) | |
download | op-kernel-dev-7240cdec60b136f3e64a453c7fbded4ed1aa047e.zip op-kernel-dev-7240cdec60b136f3e64a453c7fbded4ed1aa047e.tar.gz |
6lowpan: handling 6lowpan fragmentation via inet_frag api
This patch drops the current way of 6lowpan fragmentation on receiving
side and replace it with a implementation which use the inet_frag api.
The old fragmentation handling has some race conditions and isn't
rfc4944 compatible. Also adding support to match fragments on
destination address, source address, tag value and datagram_size
which is missing in the current implementation.
Signed-off-by: Alexander Aring <alex.aring@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ieee802154/reassembly.c')
-rw-r--r-- | net/ieee802154/reassembly.c | 564 |
1 files changed, 564 insertions, 0 deletions
diff --git a/net/ieee802154/reassembly.c b/net/ieee802154/reassembly.c new file mode 100644 index 0000000..eb5995e --- /dev/null +++ b/net/ieee802154/reassembly.c @@ -0,0 +1,564 @@ +/* 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/ipv6.h> +#include <net/inet_frag.h> + +#include "6lowpan.h" +#include "reassembly.h" + +static struct inet_frags lowpan_frags; + +static int lowpan_frag_reasm(struct lowpan_frag_queue *fq, + struct sk_buff *prev, struct net_device *dev); + +static unsigned int lowpan_hash_frag(__be16 tag, __be16 d_size, + const struct ieee802154_addr *saddr, + const struct ieee802154_addr *daddr) +{ + u32 c; + + net_get_random_once(&lowpan_frags.rnd, sizeof(lowpan_frags.rnd)); + c = jhash_3words(ieee802154_addr_hash(saddr), + ieee802154_addr_hash(daddr), + (__force u32)(tag + (d_size << 16)), + lowpan_frags.rnd); + + return c & (INETFRAGS_HASHSZ - 1); +} + +static unsigned int lowpan_hashfn(struct inet_frag_queue *q) +{ + struct lowpan_frag_queue *fq; + + fq = container_of(q, struct lowpan_frag_queue, q); + return lowpan_hash_frag(fq->tag, fq->d_size, &fq->saddr, &fq->daddr); +} + +bool lowpan_frag_match(struct inet_frag_queue *q, void *a) +{ + struct lowpan_frag_queue *fq; + struct lowpan_create_arg *arg = a; + + fq = container_of(q, struct lowpan_frag_queue, q); + return fq->tag == arg->tag && fq->d_size == arg->d_size && + ieee802154_addr_addr_equal(&fq->saddr, arg->src) && + ieee802154_addr_addr_equal(&fq->daddr, arg->dst); +} +EXPORT_SYMBOL(lowpan_frag_match); + +void lowpan_frag_init(struct inet_frag_queue *q, void *a) +{ + struct lowpan_frag_queue *fq; + struct lowpan_create_arg *arg = a; + + fq = container_of(q, struct lowpan_frag_queue, q); + + fq->tag = arg->tag; + fq->d_size = arg->d_size; + fq->saddr = *arg->src; + fq->daddr = *arg->dst; +} +EXPORT_SYMBOL(lowpan_frag_init); + +void lowpan_expire_frag_queue(struct frag_queue *fq, struct inet_frags *frags) +{ + spin_lock(&fq->q.lock); + + if (fq->q.last_in & INET_FRAG_COMPLETE) + goto out; + + inet_frag_kill(&fq->q, frags); +out: + spin_unlock(&fq->q.lock); + inet_frag_put(&fq->q, frags); +} +EXPORT_SYMBOL(lowpan_expire_frag_queue); + +static void lowpan_frag_expire(unsigned long data) +{ + struct frag_queue *fq; + struct net *net; + + fq = container_of((struct inet_frag_queue *)data, struct frag_queue, q); + net = container_of(fq->q.net, struct net, ieee802154_lowpan.frags); + + lowpan_expire_frag_queue(fq, &lowpan_frags); +} + +static inline struct lowpan_frag_queue * +fq_find(struct net *net, const struct ieee802154_frag_info *frag_info, + const struct ieee802154_addr *src, const struct ieee802154_addr *dst) +{ + struct inet_frag_queue *q; + struct lowpan_create_arg arg; + unsigned int hash; + + arg.tag = frag_info->d_tag; + arg.d_size = frag_info->d_size; + arg.src = src; + arg.dst = dst; + + read_lock(&lowpan_frags.lock); + hash = lowpan_hash_frag(frag_info->d_tag, frag_info->d_size, src, dst); + + q = inet_frag_find(&net->ieee802154_lowpan.frags, + &lowpan_frags, &arg, hash); + if (IS_ERR_OR_NULL(q)) { + inet_frag_maybe_warn_overflow(q, pr_fmt()); + 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, const u8 frag_type) +{ + struct sk_buff *prev, *next; + struct net_device *dev; + int end, offset; + + if (fq->q.last_in & INET_FRAG_COMPLETE) + goto err; + + offset = mac_cb(skb)->frag_info.d_offset << 3; + end = mac_cb(skb)->frag_info.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.last_in & INET_FRAG_LAST_IN) && end != fq->q.len)) + goto err; + fq->q.last_in |= INET_FRAG_LAST_IN; + fq->q.len = end; + } else { + if (end > fq->q.len) { + /* Some bits beyond end -> corruption. */ + if (fq->q.last_in & 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 || mac_cb(prev)->frag_info.d_offset < + mac_cb(skb)->frag_info.d_offset) { + next = NULL; + goto found; + } + prev = NULL; + for (next = fq->q.fragments; next != NULL; next = next->next) { + if (mac_cb(next)->frag_info.d_offset >= + mac_cb(skb)->frag_info.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; + + dev = skb->dev; + if (dev) + skb->dev = NULL; + + fq->q.stamp = skb->tstamp; + if (frag_type == LOWPAN_DISPATCH_FRAG1) { + /* Calculate uncomp. 6lowpan header to estimate full size */ + fq->q.meat += lowpan_uncompress_size(skb, NULL); + fq->q.last_in |= INET_FRAG_FIRST_IN; + } else { + fq->q.meat += skb->len; + } + add_frag_mem_limit(&fq->q, skb->truesize); + + if (fq->q.last_in == (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, dev); + skb->_skb_refdst = orefdst; + return res; + } + + inet_frag_lru_move(&fq->q); + 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 *dev) +{ + struct sk_buff *fp, *head = fq->q.fragments; + int sum_truesize; + + inet_frag_kill(&fq->q, &lowpan_frags); + + /* 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, 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, sum_truesize); + + head->next = NULL; + head->dev = dev; + 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_get_frag_info(struct sk_buff *skb, const u8 frag_type, + struct ieee802154_frag_info *frag_info) +{ + bool fail; + u8 pattern = 0, low = 0; + + fail = lowpan_fetch_skb(skb, &pattern, 1); + fail |= lowpan_fetch_skb(skb, &low, 1); + frag_info->d_size = (pattern & 7) << 8 | low; + fail |= lowpan_fetch_skb(skb, &frag_info->d_tag, 2); + + if (frag_type == LOWPAN_DISPATCH_FRAGN) { + fail |= lowpan_fetch_skb(skb, &frag_info->d_offset, 1); + } else { + skb_reset_network_header(skb); + frag_info->d_offset = 0; + } + + if (unlikely(fail)) + return -EIO; + + return 0; +} + +int lowpan_frag_rcv(struct sk_buff *skb, const u8 frag_type) +{ + struct lowpan_frag_queue *fq; + struct net *net = dev_net(skb->dev); + struct ieee802154_frag_info *frag_info = &mac_cb(skb)->frag_info; + int err; + + err = lowpan_get_frag_info(skb, frag_type, frag_info); + if (err < 0) + goto err; + + if (frag_info->d_size > net->ieee802154_lowpan.max_dsize) + goto err; + + inet_frag_evictor(&net->ieee802154_lowpan.frags, &lowpan_frags, false); + + fq = fq_find(net, frag_info, &mac_cb(skb)->sa, &mac_cb(skb)->da); + 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, &lowpan_frags); + return ret; + } + +err: + kfree_skb(skb); + return -1; +} +EXPORT_SYMBOL(lowpan_frag_rcv); + +#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(int), + .mode = 0644, + .proc_handler = proc_dointvec + }, + { + .procname = "6lowpanfrag_low_thresh", + .data = &init_net.ieee802154_lowpan.frags.low_thresh, + .maxlen = sizeof(int), + .mode = 0644, + .proc_handler = proc_dointvec + }, + { + .procname = "6lowpanfrag_time", + .data = &init_net.ieee802154_lowpan.frags.timeout, + .maxlen = sizeof(int), + .mode = 0644, + .proc_handler = proc_dointvec_jiffies, + }, + { + .procname = "6lowpanfrag_max_datagram_size", + .data = &init_net.ieee802154_lowpan.max_dsize, + .maxlen = sizeof(int), + .mode = 0644, + .proc_handler = proc_dointvec + }, + { } +}; + +static struct ctl_table lowpan_frags_ctl_table[] = { + { + .procname = "6lowpanfrag_secret_interval", + .data = &lowpan_frags.secret_interval, + .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; + + 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 = &net->ieee802154_lowpan.frags.high_thresh; + table[1].data = &net->ieee802154_lowpan.frags.low_thresh; + table[2].data = &net->ieee802154_lowpan.frags.timeout; + table[2].data = &net->ieee802154_lowpan.max_dsize; + + /* 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; + + net->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; + + table = net->ieee802154_lowpan.sysctl.frags_hdr->ctl_table_arg; + unregister_net_sysctl_table(net->ieee802154_lowpan.sysctl.frags_hdr); + if (!net_eq(net, &init_net)) + kfree(table); +} + +static struct ctl_table_header *lowpan_ctl_header; + +static int 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 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) +{ + net->ieee802154_lowpan.frags.high_thresh = IPV6_FRAG_HIGH_THRESH; + net->ieee802154_lowpan.frags.low_thresh = IPV6_FRAG_LOW_THRESH; + net->ieee802154_lowpan.frags.timeout = IPV6_FRAG_TIMEOUT; + net->ieee802154_lowpan.max_dsize = 0xFFFF; + + inet_frags_init_net(&net->ieee802154_lowpan.frags); + + return lowpan_frags_ns_sysctl_register(net); +} + +static void __net_exit lowpan_frags_exit_net(struct net *net) +{ + lowpan_frags_ns_sysctl_unregister(net); + inet_frags_exit_net(&net->ieee802154_lowpan.frags, &lowpan_frags); +} + +static struct pernet_operations lowpan_frags_ops = { + .init = lowpan_frags_init_net, + .exit = lowpan_frags_exit_net, +}; + +int __init lowpan_net_frag_init(void) +{ + int ret; + + ret = lowpan_frags_sysctl_register(); + if (ret) + goto out; + + ret = register_pernet_subsys(&lowpan_frags_ops); + if (ret) + goto err_pernet; + + lowpan_frags.hashfn = lowpan_hashfn; + lowpan_frags.constructor = lowpan_frag_init; + lowpan_frags.destructor = NULL; + lowpan_frags.skb_free = NULL; + lowpan_frags.qsize = sizeof(struct frag_queue); + lowpan_frags.match = lowpan_frag_match; + lowpan_frags.frag_expire = lowpan_frag_expire; + lowpan_frags.secret_interval = 10 * 60 * HZ; + inet_frags_init(&lowpan_frags); +err_pernet: + lowpan_frags_sysctl_unregister(); +out: + return ret; +} + +void lowpan_net_frag_exit(void) +{ + inet_frags_fini(&lowpan_frags); + lowpan_frags_sysctl_unregister(); + unregister_pernet_subsys(&lowpan_frags_ops); +} |