| /* 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.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 unsigned int lowpan_hash_frag(u16 tag, u16 d_size, |
| const struct ieee802154_addr *saddr, |
| const struct ieee802154_addr *daddr) |
| { |
| net_get_random_once(&lowpan_frags.rnd, sizeof(lowpan_frags.rnd)); |
| return jhash_3words(ieee802154_addr_hash(saddr), |
| ieee802154_addr_hash(daddr), |
| (__force u32)(tag + (d_size << 16)), |
| lowpan_frags.rnd); |
| } |
| |
| static unsigned int lowpan_hashfn(const struct inet_frag_queue *q) |
| { |
| const 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); |
| } |
| |
| static bool lowpan_frag_match(const struct inet_frag_queue *q, const void *a) |
| { |
| const struct lowpan_frag_queue *fq; |
| const 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_equal(&fq->saddr, arg->src) && |
| ieee802154_addr_equal(&fq->daddr, arg->dst); |
| } |
| |
| static void lowpan_frag_init(struct inet_frag_queue *q, const void *a) |
| { |
| const struct lowpan_create_arg *arg = a; |
| struct lowpan_frag_queue *fq; |
| |
| 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; |
| } |
| |
| static void lowpan_frag_expire(struct timer_list *t) |
| { |
| struct inet_frag_queue *frag = from_timer(frag, t, timer); |
| struct frag_queue *fq; |
| struct net *net; |
| |
| fq = container_of(frag, struct frag_queue, q); |
| net = container_of(fq->q.net, struct net, ieee802154_lowpan.frags); |
| |
| spin_lock(&fq->q.lock); |
| |
| if (fq->q.flags & INET_FRAG_COMPLETE) |
| goto out; |
| |
| inet_frag_kill(&fq->q, &lowpan_frags); |
| out: |
| spin_unlock(&fq->q.lock); |
| inet_frag_put(&fq->q, &lowpan_frags); |
| } |
| |
| 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 inet_frag_queue *q; |
| struct lowpan_create_arg arg; |
| unsigned int hash; |
| struct netns_ieee802154_lowpan *ieee802154_lowpan = |
| net_ieee802154_lowpan(net); |
| |
| arg.tag = cb->d_tag; |
| arg.d_size = cb->d_size; |
| arg.src = src; |
| arg.dst = dst; |
| |
| hash = lowpan_hash_frag(cb->d_tag, cb->d_size, src, dst); |
| |
| q = inet_frag_find(&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, 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, &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.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, &lowpan_frags); |
| return ret; |
| } |
| |
| err: |
| kfree_skb(skb); |
| return -1; |
| } |
| |
| #ifdef CONFIG_SYSCTL |
| static int zero; |
| |
| 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_minmax, |
| .extra1 = &init_net.ieee802154_lowpan.frags.low_thresh |
| }, |
| { |
| .procname = "6lowpanfrag_low_thresh", |
| .data = &init_net.ieee802154_lowpan.frags.low_thresh, |
| .maxlen = sizeof(int), |
| .mode = 0644, |
| .proc_handler = proc_dointvec_minmax, |
| .extra1 = &zero, |
| .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); |
| |
| 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; |
| |
| inet_frags_init_net(&ieee802154_lowpan->frags); |
| |
| return lowpan_frags_ns_sysctl_register(net); |
| } |
| |
| 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, &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) |
| return ret; |
| |
| 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.qsize = sizeof(struct frag_queue); |
| lowpan_frags.match = lowpan_frag_match; |
| lowpan_frags.frag_expire = lowpan_frag_expire; |
| lowpan_frags.frags_cache_name = lowpan_frags_cache_name; |
| ret = inet_frags_init(&lowpan_frags); |
| if (ret) |
| goto err_pernet; |
| |
| return ret; |
| err_pernet: |
| lowpan_frags_sysctl_unregister(); |
| return ret; |
| } |
| |
| void lowpan_net_frag_exit(void) |
| { |
| inet_frags_fini(&lowpan_frags); |
| lowpan_frags_sysctl_unregister(); |
| unregister_pernet_subsys(&lowpan_frags_ops); |
| } |