linux/net/ipv6/reassembly.c
Jozsef Kadlecsik 82a39eb6b3 ipv6: Prepare the tree for un-inlined jhash.
jhash is widely used in the kernel and because the functions
are inlined, the cost in size is significant. Also, the new jhash
functions are slightly larger than the previous ones so better un-inline.
As a preparation step, the calls to the internal macros are replaced
with the plain jhash function calls.

Signed-off-by: Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>
Signed-off-by: David S. Miller <davem@davemloft.net>
2010-11-28 11:26:21 -08:00

770 lines
19 KiB
C

/*
* IPv6 fragment reassembly
* Linux INET6 implementation
*
* Authors:
* Pedro Roque <roque@di.fc.ul.pt>
*
* Based on: net/ipv4/ip_fragment.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.
*/
/*
* 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.
*/
#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 <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/inet_frag.h>
struct ip6frag_skb_cb
{
struct inet6_skb_parm h;
int offset;
};
#define FRAG6_CB(skb) ((struct ip6frag_skb_cb*)((skb)->cb))
/*
* Equivalent of ipv4 struct ipq
*/
struct frag_queue
{
struct inet_frag_queue q;
__be32 id; /* fragment id */
u32 user;
struct in6_addr saddr;
struct in6_addr daddr;
int iif;
unsigned int csum;
__u16 nhoffset;
};
static struct inet_frags ip6_frags;
int ip6_frag_nqueues(struct net *net)
{
return net->ipv6.frags.nqueues;
}
int ip6_frag_mem(struct net *net)
{
return atomic_read(&net->ipv6.frags.mem);
}
static int ip6_frag_reasm(struct frag_queue *fq, struct sk_buff *prev,
struct net_device *dev);
/*
* callers should be careful not to use the hash value outside the ipfrag_lock
* as doing so could race with ipfrag_hash_rnd being recalculated.
*/
unsigned int inet6_hash_frag(__be32 id, const struct in6_addr *saddr,
const struct in6_addr *daddr, u32 rnd)
{
u32 c;
c = jhash_3words((__force u32)saddr->s6_addr32[0],
(__force u32)saddr->s6_addr32[1],
(__force u32)saddr->s6_addr32[2],
rnd);
c = jhash_3words((__force u32)saddr->s6_addr32[3],
(__force u32)daddr->s6_addr32[0],
(__force u32)daddr->s6_addr32[1],
c);
c = jhash_3words((__force u32)daddr->s6_addr32[2],
(__force u32)daddr->s6_addr32[3],
(__force u32)id,
c);
return c & (INETFRAGS_HASHSZ - 1);
}
EXPORT_SYMBOL_GPL(inet6_hash_frag);
static unsigned int ip6_hashfn(struct inet_frag_queue *q)
{
struct frag_queue *fq;
fq = container_of(q, struct frag_queue, q);
return inet6_hash_frag(fq->id, &fq->saddr, &fq->daddr, ip6_frags.rnd);
}
int ip6_frag_match(struct inet_frag_queue *q, void *a)
{
struct frag_queue *fq;
struct ip6_create_arg *arg = a;
fq = container_of(q, struct frag_queue, q);
return (fq->id == arg->id && fq->user == arg->user &&
ipv6_addr_equal(&fq->saddr, arg->src) &&
ipv6_addr_equal(&fq->daddr, arg->dst));
}
EXPORT_SYMBOL(ip6_frag_match);
void ip6_frag_init(struct inet_frag_queue *q, void *a)
{
struct frag_queue *fq = container_of(q, struct frag_queue, q);
struct ip6_create_arg *arg = a;
fq->id = arg->id;
fq->user = arg->user;
ipv6_addr_copy(&fq->saddr, arg->src);
ipv6_addr_copy(&fq->daddr, arg->dst);
}
EXPORT_SYMBOL(ip6_frag_init);
/* Destruction primitives. */
static __inline__ void fq_put(struct frag_queue *fq)
{
inet_frag_put(&fq->q, &ip6_frags);
}
/* Kill fq entry. It is not destroyed immediately,
* because caller (and someone more) holds reference count.
*/
static __inline__ void fq_kill(struct frag_queue *fq)
{
inet_frag_kill(&fq->q, &ip6_frags);
}
static void ip6_evictor(struct net *net, struct inet6_dev *idev)
{
int evicted;
evicted = inet_frag_evictor(&net->ipv6.frags, &ip6_frags);
if (evicted)
IP6_ADD_STATS_BH(net, idev, IPSTATS_MIB_REASMFAILS, evicted);
}
static void ip6_frag_expire(unsigned long data)
{
struct frag_queue *fq;
struct net_device *dev = NULL;
struct net *net;
fq = container_of((struct inet_frag_queue *)data, struct frag_queue, q);
spin_lock(&fq->q.lock);
if (fq->q.last_in & INET_FRAG_COMPLETE)
goto out;
fq_kill(fq);
net = container_of(fq->q.net, struct net, ipv6.frags);
rcu_read_lock();
dev = dev_get_by_index_rcu(net, fq->iif);
if (!dev)
goto out_rcu_unlock;
IP6_INC_STATS_BH(net, __in6_dev_get(dev), IPSTATS_MIB_REASMTIMEOUT);
IP6_INC_STATS_BH(net, __in6_dev_get(dev), IPSTATS_MIB_REASMFAILS);
/* Don't send error if the first segment did not arrive. */
if (!(fq->q.last_in & INET_FRAG_FIRST_IN) || !fq->q.fragments)
goto out_rcu_unlock;
/*
But use as source device on which LAST ARRIVED
segment was received. And do not use fq->dev
pointer directly, device might already disappeared.
*/
fq->q.fragments->dev = dev;
icmpv6_send(fq->q.fragments, ICMPV6_TIME_EXCEED, ICMPV6_EXC_FRAGTIME, 0);
out_rcu_unlock:
rcu_read_unlock();
out:
spin_unlock(&fq->q.lock);
fq_put(fq);
}
static __inline__ struct frag_queue *
fq_find(struct net *net, __be32 id, struct in6_addr *src, struct in6_addr *dst)
{
struct inet_frag_queue *q;
struct ip6_create_arg arg;
unsigned int hash;
arg.id = id;
arg.user = IP6_DEFRAG_LOCAL_DELIVER;
arg.src = src;
arg.dst = dst;
read_lock(&ip6_frags.lock);
hash = inet6_hash_frag(id, src, dst, ip6_frags.rnd);
q = inet_frag_find(&net->ipv6.frags, &ip6_frags, &arg, hash);
if (q == NULL)
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)
{
struct sk_buff *prev, *next;
struct net_device *dev;
int offset, end;
struct net *net = dev_net(skb_dst(skb)->dev);
if (fq->q.last_in & INET_FRAG_COMPLETE)
goto err;
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) {
IP6_INC_STATS_BH(net, ip6_dst_idev(skb_dst(skb)),
IPSTATS_MIB_INHDRERRORS);
icmpv6_param_prob(skb, ICMPV6_HDR_FIELD,
((u8 *)&fhdr->frag_off -
skb_network_header(skb)));
return -1;
}
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.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 {
/* 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
*/
IP6_INC_STATS_BH(net, ip6_dst_idev(skb_dst(skb)),
IPSTATS_MIB_INHDRERRORS);
icmpv6_param_prob(skb, ICMPV6_HDR_FIELD,
offsetof(struct ipv6hdr, payload_len));
return -1;
}
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;
}
}
if (end == offset)
goto err;
/* Point into the IP datagram 'data' part. */
if (!pskb_pull(skb, (u8 *) (fhdr + 1) - skb->data))
goto err;
if (pskb_trim_rcsum(skb, end - offset))
goto err;
/* 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 || FRAG6_CB(prev)->offset < offset) {
next = NULL;
goto found;
}
prev = NULL;
for(next = fq->q.fragments; next != NULL; next = next->next) {
if (FRAG6_CB(next)->offset >= offset)
break; /* bingo! */
prev = next;
}
found:
/* RFC5722, Section 4:
* When reassembling an IPv6 datagram, if
* one or more its constituent fragments is determined to be an
* overlapping fragment, the entire datagram (and any constituent
* fragments, including those not yet received) MUST be silently
* discarded.
*/
/* Check for overlap with preceding fragment. */
if (prev &&
(FRAG6_CB(prev)->offset + prev->len) > offset)
goto discard_fq;
/* Look for overlap with succeeding segment. */
if (next && FRAG6_CB(next)->offset < end)
goto discard_fq;
FRAG6_CB(skb)->offset = offset;
/* 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) {
fq->iif = dev->ifindex;
skb->dev = NULL;
}
fq->q.stamp = skb->tstamp;
fq->q.meat += skb->len;
atomic_add(skb->truesize, &fq->q.net->mem);
/* The first fragment.
* nhoffset is obtained from the first fragment, of course.
*/
if (offset == 0) {
fq->nhoffset = nhoff;
fq->q.last_in |= INET_FRAG_FIRST_IN;
}
if (fq->q.last_in == (INET_FRAG_FIRST_IN | INET_FRAG_LAST_IN) &&
fq->q.meat == fq->q.len)
return ip6_frag_reasm(fq, prev, dev);
write_lock(&ip6_frags.lock);
list_move_tail(&fq->q.lru_list, &fq->q.net->lru_list);
write_unlock(&ip6_frags.lock);
return -1;
discard_fq:
fq_kill(fq);
err:
IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)),
IPSTATS_MIB_REASMFAILS);
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 ip6_frag_reasm(struct frag_queue *fq, struct sk_buff *prev,
struct net_device *dev)
{
struct net *net = container_of(fq->q.net, struct net, ipv6.frags);
struct sk_buff *fp, *head = fq->q.fragments;
int payload_len;
unsigned int nhoff;
fq_kill(fq);
/* 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;
kfree_skb(fq->q.fragments);
fq->q.fragments = head;
}
WARN_ON(head == NULL);
WARN_ON(FRAG6_CB(head)->offset != 0);
/* Unfragmented part is taken from the first segment. */
payload_len = ((head->data - skb_network_header(head)) -
sizeof(struct ipv6hdr) + fq->q.len -
sizeof(struct frag_hdr));
if (payload_len > IPV6_MAXPLEN)
goto out_oversize;
/* Head of list must not be cloned. */
if (skb_cloned(head) && pskb_expand_head(head, 0, 0, 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;
if ((clone = alloc_skb(0, GFP_ATOMIC)) == NULL)
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_shinfo(head)->frags[i].size;
clone->len = clone->data_len = head->data_len - plen;
head->data_len -= clone->len;
head->len -= clone->len;
clone->csum = 0;
clone->ip_summed = head->ip_summed;
atomic_add(clone->truesize, &fq->q.net->mem);
}
/* We have to remove fragment header from datagram and to relocate
* header in order to calculate ICV correctly. */
nhoff = fq->nhoffset;
skb_network_header(head)[nhoff] = skb_transport_header(head)[0];
memmove(head->head + sizeof(struct frag_hdr), head->head,
(head->data - head->head) - sizeof(struct frag_hdr));
head->mac_header += sizeof(struct frag_hdr);
head->network_header += sizeof(struct frag_hdr);
skb_shinfo(head)->frag_list = head->next;
skb_reset_transport_header(head);
skb_push(head, head->data - skb_network_header(head));
for (fp=head->next; fp; fp = fp->next) {
head->data_len += fp->len;
head->len += fp->len;
if (head->ip_summed != fp->ip_summed)
head->ip_summed = CHECKSUM_NONE;
else if (head->ip_summed == CHECKSUM_COMPLETE)
head->csum = csum_add(head->csum, fp->csum);
head->truesize += fp->truesize;
}
atomic_sub(head->truesize, &fq->q.net->mem);
head->next = NULL;
head->dev = dev;
head->tstamp = fq->q.stamp;
ipv6_hdr(head)->payload_len = htons(payload_len);
IP6CB(head)->nhoff = nhoff;
/* Yes, and fold redundant checksum back. 8) */
if (head->ip_summed == CHECKSUM_COMPLETE)
head->csum = csum_partial(skb_network_header(head),
skb_network_header_len(head),
head->csum);
rcu_read_lock();
IP6_INC_STATS_BH(net, __in6_dev_get(dev), IPSTATS_MIB_REASMOKS);
rcu_read_unlock();
fq->q.fragments = NULL;
fq->q.fragments_tail = NULL;
return 1;
out_oversize:
if (net_ratelimit())
printk(KERN_DEBUG "ip6_frag_reasm: payload len = %d\n", payload_len);
goto out_fail;
out_oom:
if (net_ratelimit())
printk(KERN_DEBUG "ip6_frag_reasm: no memory for reassembly\n");
out_fail:
rcu_read_lock();
IP6_INC_STATS_BH(net, __in6_dev_get(dev), IPSTATS_MIB_REASMFAILS);
rcu_read_unlock();
return -1;
}
static int ipv6_frag_rcv(struct sk_buff *skb)
{
struct frag_hdr *fhdr;
struct frag_queue *fq;
struct ipv6hdr *hdr = ipv6_hdr(skb);
struct net *net = dev_net(skb_dst(skb)->dev);
IP6_INC_STATS_BH(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(0xFFF9))) {
/* It is not a fragmented frame */
skb->transport_header += sizeof(struct frag_hdr);
IP6_INC_STATS_BH(net,
ip6_dst_idev(skb_dst(skb)), IPSTATS_MIB_REASMOKS);
IP6CB(skb)->nhoff = (u8 *)fhdr - skb_network_header(skb);
return 1;
}
if (atomic_read(&net->ipv6.frags.mem) > net->ipv6.frags.high_thresh)
ip6_evictor(net, ip6_dst_idev(skb_dst(skb)));
fq = fq_find(net, fhdr->identification, &hdr->saddr, &hdr->daddr);
if (fq != NULL) {
int ret;
spin_lock(&fq->q.lock);
ret = ip6_frag_queue(fq, skb, fhdr, IP6CB(skb)->nhoff);
spin_unlock(&fq->q.lock);
fq_put(fq);
return ret;
}
IP6_INC_STATS_BH(net, ip6_dst_idev(skb_dst(skb)), IPSTATS_MIB_REASMFAILS);
kfree_skb(skb);
return -1;
fail_hdr:
IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)), 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",
.data = &init_net.ipv6.frags.high_thresh,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = proc_dointvec
},
{
.procname = "ip6frag_low_thresh",
.data = &init_net.ipv6.frags.low_thresh,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = proc_dointvec
},
{
.procname = "ip6frag_time",
.data = &init_net.ipv6.frags.timeout,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = proc_dointvec_jiffies,
},
{ }
};
static struct ctl_table ip6_frags_ctl_table[] = {
{
.procname = "ip6frag_secret_interval",
.data = &ip6_frags.secret_interval,
.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 == NULL)
goto err_alloc;
table[0].data = &net->ipv6.frags.high_thresh;
table[1].data = &net->ipv6.frags.low_thresh;
table[2].data = &net->ipv6.frags.timeout;
}
hdr = register_net_sysctl_table(net, net_ipv6_ctl_path, table);
if (hdr == NULL)
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_rotable(net_ipv6_ctl_path,
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 inline int ip6_frags_ns_sysctl_register(struct net *net)
{
return 0;
}
static inline void ip6_frags_ns_sysctl_unregister(struct net *net)
{
}
static inline int ip6_frags_sysctl_register(void)
{
return 0;
}
static inline void ip6_frags_sysctl_unregister(void)
{
}
#endif
static int __net_init ipv6_frags_init_net(struct net *net)
{
net->ipv6.frags.high_thresh = IPV6_FRAG_HIGH_THRESH;
net->ipv6.frags.low_thresh = IPV6_FRAG_LOW_THRESH;
net->ipv6.frags.timeout = IPV6_FRAG_TIMEOUT;
inet_frags_init_net(&net->ipv6.frags);
return ip6_frags_ns_sysctl_register(net);
}
static void __net_exit ipv6_frags_exit_net(struct net *net)
{
ip6_frags_ns_sysctl_unregister(net);
inet_frags_exit_net(&net->ipv6.frags, &ip6_frags);
}
static struct pernet_operations ip6_frags_ops = {
.init = ipv6_frags_init_net,
.exit = ipv6_frags_exit_net,
};
int __init ipv6_frag_init(void)
{
int ret;
ret = inet6_add_protocol(&frag_protocol, IPPROTO_FRAGMENT);
if (ret)
goto out;
ret = ip6_frags_sysctl_register();
if (ret)
goto err_sysctl;
ret = register_pernet_subsys(&ip6_frags_ops);
if (ret)
goto err_pernet;
ip6_frags.hashfn = ip6_hashfn;
ip6_frags.constructor = ip6_frag_init;
ip6_frags.destructor = NULL;
ip6_frags.skb_free = NULL;
ip6_frags.qsize = sizeof(struct frag_queue);
ip6_frags.match = ip6_frag_match;
ip6_frags.frag_expire = ip6_frag_expire;
ip6_frags.secret_interval = 10 * 60 * HZ;
inet_frags_init(&ip6_frags);
out:
return ret;
err_pernet:
ip6_frags_sysctl_unregister();
err_sysctl:
inet6_del_protocol(&frag_protocol, IPPROTO_FRAGMENT);
goto out;
}
void ipv6_frag_exit(void)
{
inet_frags_fini(&ip6_frags);
ip6_frags_sysctl_unregister();
unregister_pernet_subsys(&ip6_frags_ops);
inet6_del_protocol(&frag_protocol, IPPROTO_FRAGMENT);
}