![Florian Westphal](/assets/img/avatar_default.png)
We currently always send fragments without DF bit set. Thus, given following setup: mtu1500 - mtu1500:1400 - mtu1400:1280 - mtu1280 A R1 R2 B Where R1 and R2 run linux with netfilter defragmentation/conntrack enabled, then if Host A sent a fragmented packet _with_ DF set to B, R1 will respond with icmp too big error if one of these fragments exceeded 1400 bytes. However, if R1 receives fragment sizes 1200 and 100, it would forward the reassembled packet without refragmenting, i.e. R2 will send an icmp error in response to a packet that was never sent, citing mtu that the original sender never exceeded. The other minor issue is that a refragmentation on R1 will conceal the MTU of R2-B since refragmentation does not set DF bit on the fragments. This modifies ip_fragment so that we track largest fragment size seen both for DF and non-DF packets, and set frag_max_size to the largest value. If the DF fragment size is larger or equal to the non-df one, we will consider the packet a path mtu probe: We set DF bit on the reassembled skb and also tag it with a new IPCB flag to force refragmentation even if skb fits outdev mtu. We will also set DF bit on each fragment in this case. Joint work with Hannes Frederic Sowa. Reported-by: Jesse Gross <jesse@nicira.com> Signed-off-by: Florian Westphal <fw@strlen.de> Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org> Signed-off-by: David S. Miller <davem@davemloft.net>
900 lines
21 KiB
C
900 lines
21 KiB
C
/*
|
|
* INET An implementation of the TCP/IP protocol suite for the LINUX
|
|
* operating system. INET is implemented using the BSD Socket
|
|
* interface as the means of communication with the user level.
|
|
*
|
|
* The IP fragmentation functionality.
|
|
*
|
|
* Authors: Fred N. van Kempen <waltje@uWalt.NL.Mugnet.ORG>
|
|
* Alan Cox <alan@lxorguk.ukuu.org.uk>
|
|
*
|
|
* Fixes:
|
|
* Alan Cox : Split from ip.c , see ip_input.c for history.
|
|
* David S. Miller : Begin massive cleanup...
|
|
* Andi Kleen : Add sysctls.
|
|
* xxxx : Overlapfrag bug.
|
|
* Ultima : ip_expire() kernel panic.
|
|
* Bill Hawes : Frag accounting and evictor fixes.
|
|
* John McDonald : 0 length frag bug.
|
|
* Alexey Kuznetsov: SMP races, threading, cleanup.
|
|
* Patrick McHardy : LRU queue of frag heads for evictor.
|
|
*/
|
|
|
|
#define pr_fmt(fmt) "IPv4: " fmt
|
|
|
|
#include <linux/compiler.h>
|
|
#include <linux/module.h>
|
|
#include <linux/types.h>
|
|
#include <linux/mm.h>
|
|
#include <linux/jiffies.h>
|
|
#include <linux/skbuff.h>
|
|
#include <linux/list.h>
|
|
#include <linux/ip.h>
|
|
#include <linux/icmp.h>
|
|
#include <linux/netdevice.h>
|
|
#include <linux/jhash.h>
|
|
#include <linux/random.h>
|
|
#include <linux/slab.h>
|
|
#include <net/route.h>
|
|
#include <net/dst.h>
|
|
#include <net/sock.h>
|
|
#include <net/ip.h>
|
|
#include <net/icmp.h>
|
|
#include <net/checksum.h>
|
|
#include <net/inetpeer.h>
|
|
#include <net/inet_frag.h>
|
|
#include <linux/tcp.h>
|
|
#include <linux/udp.h>
|
|
#include <linux/inet.h>
|
|
#include <linux/netfilter_ipv4.h>
|
|
#include <net/inet_ecn.h>
|
|
|
|
/* NOTE. Logic of IP defragmentation is parallel to corresponding IPv6
|
|
* code now. If you change something here, _PLEASE_ update ipv6/reassembly.c
|
|
* as well. Or notify me, at least. --ANK
|
|
*/
|
|
|
|
static int sysctl_ipfrag_max_dist __read_mostly = 64;
|
|
static const char ip_frag_cache_name[] = "ip4-frags";
|
|
|
|
struct ipfrag_skb_cb
|
|
{
|
|
struct inet_skb_parm h;
|
|
int offset;
|
|
};
|
|
|
|
#define FRAG_CB(skb) ((struct ipfrag_skb_cb *)((skb)->cb))
|
|
|
|
/* Describe an entry in the "incomplete datagrams" queue. */
|
|
struct ipq {
|
|
struct inet_frag_queue q;
|
|
|
|
u32 user;
|
|
__be32 saddr;
|
|
__be32 daddr;
|
|
__be16 id;
|
|
u8 protocol;
|
|
u8 ecn; /* RFC3168 support */
|
|
u16 max_df_size; /* largest frag with DF set seen */
|
|
int iif;
|
|
unsigned int rid;
|
|
struct inet_peer *peer;
|
|
};
|
|
|
|
static u8 ip4_frag_ecn(u8 tos)
|
|
{
|
|
return 1 << (tos & INET_ECN_MASK);
|
|
}
|
|
|
|
static struct inet_frags ip4_frags;
|
|
|
|
int ip_frag_mem(struct net *net)
|
|
{
|
|
return sum_frag_mem_limit(&net->ipv4.frags);
|
|
}
|
|
|
|
static int ip_frag_reasm(struct ipq *qp, struct sk_buff *prev,
|
|
struct net_device *dev);
|
|
|
|
struct ip4_create_arg {
|
|
struct iphdr *iph;
|
|
u32 user;
|
|
};
|
|
|
|
static unsigned int ipqhashfn(__be16 id, __be32 saddr, __be32 daddr, u8 prot)
|
|
{
|
|
net_get_random_once(&ip4_frags.rnd, sizeof(ip4_frags.rnd));
|
|
return jhash_3words((__force u32)id << 16 | prot,
|
|
(__force u32)saddr, (__force u32)daddr,
|
|
ip4_frags.rnd);
|
|
}
|
|
|
|
static unsigned int ip4_hashfn(const struct inet_frag_queue *q)
|
|
{
|
|
const struct ipq *ipq;
|
|
|
|
ipq = container_of(q, struct ipq, q);
|
|
return ipqhashfn(ipq->id, ipq->saddr, ipq->daddr, ipq->protocol);
|
|
}
|
|
|
|
static bool ip4_frag_match(const struct inet_frag_queue *q, const void *a)
|
|
{
|
|
const struct ipq *qp;
|
|
const struct ip4_create_arg *arg = a;
|
|
|
|
qp = container_of(q, struct ipq, q);
|
|
return qp->id == arg->iph->id &&
|
|
qp->saddr == arg->iph->saddr &&
|
|
qp->daddr == arg->iph->daddr &&
|
|
qp->protocol == arg->iph->protocol &&
|
|
qp->user == arg->user;
|
|
}
|
|
|
|
static void ip4_frag_init(struct inet_frag_queue *q, const void *a)
|
|
{
|
|
struct ipq *qp = container_of(q, struct ipq, q);
|
|
struct netns_ipv4 *ipv4 = container_of(q->net, struct netns_ipv4,
|
|
frags);
|
|
struct net *net = container_of(ipv4, struct net, ipv4);
|
|
|
|
const struct ip4_create_arg *arg = a;
|
|
|
|
qp->protocol = arg->iph->protocol;
|
|
qp->id = arg->iph->id;
|
|
qp->ecn = ip4_frag_ecn(arg->iph->tos);
|
|
qp->saddr = arg->iph->saddr;
|
|
qp->daddr = arg->iph->daddr;
|
|
qp->user = arg->user;
|
|
qp->peer = sysctl_ipfrag_max_dist ?
|
|
inet_getpeer_v4(net->ipv4.peers, arg->iph->saddr, 1) : NULL;
|
|
}
|
|
|
|
static void ip4_frag_free(struct inet_frag_queue *q)
|
|
{
|
|
struct ipq *qp;
|
|
|
|
qp = container_of(q, struct ipq, q);
|
|
if (qp->peer)
|
|
inet_putpeer(qp->peer);
|
|
}
|
|
|
|
|
|
/* Destruction primitives. */
|
|
|
|
static void ipq_put(struct ipq *ipq)
|
|
{
|
|
inet_frag_put(&ipq->q, &ip4_frags);
|
|
}
|
|
|
|
/* Kill ipq entry. It is not destroyed immediately,
|
|
* because caller (and someone more) holds reference count.
|
|
*/
|
|
static void ipq_kill(struct ipq *ipq)
|
|
{
|
|
inet_frag_kill(&ipq->q, &ip4_frags);
|
|
}
|
|
|
|
static bool frag_expire_skip_icmp(u32 user)
|
|
{
|
|
return user == IP_DEFRAG_AF_PACKET ||
|
|
ip_defrag_user_in_between(user, IP_DEFRAG_CONNTRACK_IN,
|
|
__IP_DEFRAG_CONNTRACK_IN_END) ||
|
|
ip_defrag_user_in_between(user, IP_DEFRAG_CONNTRACK_BRIDGE_IN,
|
|
__IP_DEFRAG_CONNTRACK_BRIDGE_IN);
|
|
}
|
|
|
|
/*
|
|
* Oops, a fragment queue timed out. Kill it and send an ICMP reply.
|
|
*/
|
|
static void ip_expire(unsigned long arg)
|
|
{
|
|
struct ipq *qp;
|
|
struct net *net;
|
|
|
|
qp = container_of((struct inet_frag_queue *) arg, struct ipq, q);
|
|
net = container_of(qp->q.net, struct net, ipv4.frags);
|
|
|
|
spin_lock(&qp->q.lock);
|
|
|
|
if (qp->q.flags & INET_FRAG_COMPLETE)
|
|
goto out;
|
|
|
|
ipq_kill(qp);
|
|
IP_INC_STATS_BH(net, IPSTATS_MIB_REASMFAILS);
|
|
|
|
if (!(qp->q.flags & INET_FRAG_EVICTED)) {
|
|
struct sk_buff *head = qp->q.fragments;
|
|
const struct iphdr *iph;
|
|
int err;
|
|
|
|
IP_INC_STATS_BH(net, IPSTATS_MIB_REASMTIMEOUT);
|
|
|
|
if (!(qp->q.flags & INET_FRAG_FIRST_IN) || !qp->q.fragments)
|
|
goto out;
|
|
|
|
rcu_read_lock();
|
|
head->dev = dev_get_by_index_rcu(net, qp->iif);
|
|
if (!head->dev)
|
|
goto out_rcu_unlock;
|
|
|
|
/* skb has no dst, perform route lookup again */
|
|
iph = ip_hdr(head);
|
|
err = ip_route_input_noref(head, iph->daddr, iph->saddr,
|
|
iph->tos, head->dev);
|
|
if (err)
|
|
goto out_rcu_unlock;
|
|
|
|
/* Only an end host needs to send an ICMP
|
|
* "Fragment Reassembly Timeout" message, per RFC792.
|
|
*/
|
|
if (frag_expire_skip_icmp(qp->user) &&
|
|
(skb_rtable(head)->rt_type != RTN_LOCAL))
|
|
goto out_rcu_unlock;
|
|
|
|
/* Send an ICMP "Fragment Reassembly Timeout" message. */
|
|
icmp_send(head, ICMP_TIME_EXCEEDED, ICMP_EXC_FRAGTIME, 0);
|
|
out_rcu_unlock:
|
|
rcu_read_unlock();
|
|
}
|
|
out:
|
|
spin_unlock(&qp->q.lock);
|
|
ipq_put(qp);
|
|
}
|
|
|
|
/* Find the correct entry in the "incomplete datagrams" queue for
|
|
* this IP datagram, and create new one, if nothing is found.
|
|
*/
|
|
static struct ipq *ip_find(struct net *net, struct iphdr *iph, u32 user)
|
|
{
|
|
struct inet_frag_queue *q;
|
|
struct ip4_create_arg arg;
|
|
unsigned int hash;
|
|
|
|
arg.iph = iph;
|
|
arg.user = user;
|
|
|
|
hash = ipqhashfn(iph->id, iph->saddr, iph->daddr, iph->protocol);
|
|
|
|
q = inet_frag_find(&net->ipv4.frags, &ip4_frags, &arg, hash);
|
|
if (IS_ERR_OR_NULL(q)) {
|
|
inet_frag_maybe_warn_overflow(q, pr_fmt());
|
|
return NULL;
|
|
}
|
|
return container_of(q, struct ipq, q);
|
|
}
|
|
|
|
/* Is the fragment too far ahead to be part of ipq? */
|
|
static int ip_frag_too_far(struct ipq *qp)
|
|
{
|
|
struct inet_peer *peer = qp->peer;
|
|
unsigned int max = sysctl_ipfrag_max_dist;
|
|
unsigned int start, end;
|
|
|
|
int rc;
|
|
|
|
if (!peer || !max)
|
|
return 0;
|
|
|
|
start = qp->rid;
|
|
end = atomic_inc_return(&peer->rid);
|
|
qp->rid = end;
|
|
|
|
rc = qp->q.fragments && (end - start) > max;
|
|
|
|
if (rc) {
|
|
struct net *net;
|
|
|
|
net = container_of(qp->q.net, struct net, ipv4.frags);
|
|
IP_INC_STATS_BH(net, IPSTATS_MIB_REASMFAILS);
|
|
}
|
|
|
|
return rc;
|
|
}
|
|
|
|
static int ip_frag_reinit(struct ipq *qp)
|
|
{
|
|
struct sk_buff *fp;
|
|
unsigned int sum_truesize = 0;
|
|
|
|
if (!mod_timer(&qp->q.timer, jiffies + qp->q.net->timeout)) {
|
|
atomic_inc(&qp->q.refcnt);
|
|
return -ETIMEDOUT;
|
|
}
|
|
|
|
fp = qp->q.fragments;
|
|
do {
|
|
struct sk_buff *xp = fp->next;
|
|
|
|
sum_truesize += fp->truesize;
|
|
kfree_skb(fp);
|
|
fp = xp;
|
|
} while (fp);
|
|
sub_frag_mem_limit(&qp->q, sum_truesize);
|
|
|
|
qp->q.flags = 0;
|
|
qp->q.len = 0;
|
|
qp->q.meat = 0;
|
|
qp->q.fragments = NULL;
|
|
qp->q.fragments_tail = NULL;
|
|
qp->iif = 0;
|
|
qp->ecn = 0;
|
|
|
|
return 0;
|
|
}
|
|
|
|
/* Add new segment to existing queue. */
|
|
static int ip_frag_queue(struct ipq *qp, struct sk_buff *skb)
|
|
{
|
|
struct sk_buff *prev, *next;
|
|
struct net_device *dev;
|
|
unsigned int fragsize;
|
|
int flags, offset;
|
|
int ihl, end;
|
|
int err = -ENOENT;
|
|
u8 ecn;
|
|
|
|
if (qp->q.flags & INET_FRAG_COMPLETE)
|
|
goto err;
|
|
|
|
if (!(IPCB(skb)->flags & IPSKB_FRAG_COMPLETE) &&
|
|
unlikely(ip_frag_too_far(qp)) &&
|
|
unlikely(err = ip_frag_reinit(qp))) {
|
|
ipq_kill(qp);
|
|
goto err;
|
|
}
|
|
|
|
ecn = ip4_frag_ecn(ip_hdr(skb)->tos);
|
|
offset = ntohs(ip_hdr(skb)->frag_off);
|
|
flags = offset & ~IP_OFFSET;
|
|
offset &= IP_OFFSET;
|
|
offset <<= 3; /* offset is in 8-byte chunks */
|
|
ihl = ip_hdrlen(skb);
|
|
|
|
/* Determine the position of this fragment. */
|
|
end = offset + skb->len - ihl;
|
|
err = -EINVAL;
|
|
|
|
/* Is this the final fragment? */
|
|
if ((flags & IP_MF) == 0) {
|
|
/* If we already have some bits beyond end
|
|
* or have different end, the segment is corrupted.
|
|
*/
|
|
if (end < qp->q.len ||
|
|
((qp->q.flags & INET_FRAG_LAST_IN) && end != qp->q.len))
|
|
goto err;
|
|
qp->q.flags |= INET_FRAG_LAST_IN;
|
|
qp->q.len = end;
|
|
} else {
|
|
if (end&7) {
|
|
end &= ~7;
|
|
if (skb->ip_summed != CHECKSUM_UNNECESSARY)
|
|
skb->ip_summed = CHECKSUM_NONE;
|
|
}
|
|
if (end > qp->q.len) {
|
|
/* Some bits beyond end -> corruption. */
|
|
if (qp->q.flags & INET_FRAG_LAST_IN)
|
|
goto err;
|
|
qp->q.len = end;
|
|
}
|
|
}
|
|
if (end == offset)
|
|
goto err;
|
|
|
|
err = -ENOMEM;
|
|
if (!pskb_pull(skb, ihl))
|
|
goto err;
|
|
|
|
err = pskb_trim_rcsum(skb, end - offset);
|
|
if (err)
|
|
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 = qp->q.fragments_tail;
|
|
if (!prev || FRAG_CB(prev)->offset < offset) {
|
|
next = NULL;
|
|
goto found;
|
|
}
|
|
prev = NULL;
|
|
for (next = qp->q.fragments; next != NULL; next = next->next) {
|
|
if (FRAG_CB(next)->offset >= offset)
|
|
break; /* bingo! */
|
|
prev = next;
|
|
}
|
|
|
|
found:
|
|
/* We found where to put this one. Check for overlap with
|
|
* preceding fragment, and, if needed, align things so that
|
|
* any overlaps are eliminated.
|
|
*/
|
|
if (prev) {
|
|
int i = (FRAG_CB(prev)->offset + prev->len) - offset;
|
|
|
|
if (i > 0) {
|
|
offset += i;
|
|
err = -EINVAL;
|
|
if (end <= offset)
|
|
goto err;
|
|
err = -ENOMEM;
|
|
if (!pskb_pull(skb, i))
|
|
goto err;
|
|
if (skb->ip_summed != CHECKSUM_UNNECESSARY)
|
|
skb->ip_summed = CHECKSUM_NONE;
|
|
}
|
|
}
|
|
|
|
err = -ENOMEM;
|
|
|
|
while (next && FRAG_CB(next)->offset < end) {
|
|
int i = end - FRAG_CB(next)->offset; /* overlap is 'i' bytes */
|
|
|
|
if (i < next->len) {
|
|
/* Eat head of the next overlapped fragment
|
|
* and leave the loop. The next ones cannot overlap.
|
|
*/
|
|
if (!pskb_pull(next, i))
|
|
goto err;
|
|
FRAG_CB(next)->offset += i;
|
|
qp->q.meat -= i;
|
|
if (next->ip_summed != CHECKSUM_UNNECESSARY)
|
|
next->ip_summed = CHECKSUM_NONE;
|
|
break;
|
|
} else {
|
|
struct sk_buff *free_it = next;
|
|
|
|
/* Old fragment is completely overridden with
|
|
* new one drop it.
|
|
*/
|
|
next = next->next;
|
|
|
|
if (prev)
|
|
prev->next = next;
|
|
else
|
|
qp->q.fragments = next;
|
|
|
|
qp->q.meat -= free_it->len;
|
|
sub_frag_mem_limit(&qp->q, free_it->truesize);
|
|
kfree_skb(free_it);
|
|
}
|
|
}
|
|
|
|
FRAG_CB(skb)->offset = offset;
|
|
|
|
/* Insert this fragment in the chain of fragments. */
|
|
skb->next = next;
|
|
if (!next)
|
|
qp->q.fragments_tail = skb;
|
|
if (prev)
|
|
prev->next = skb;
|
|
else
|
|
qp->q.fragments = skb;
|
|
|
|
dev = skb->dev;
|
|
if (dev) {
|
|
qp->iif = dev->ifindex;
|
|
skb->dev = NULL;
|
|
}
|
|
qp->q.stamp = skb->tstamp;
|
|
qp->q.meat += skb->len;
|
|
qp->ecn |= ecn;
|
|
add_frag_mem_limit(&qp->q, skb->truesize);
|
|
if (offset == 0)
|
|
qp->q.flags |= INET_FRAG_FIRST_IN;
|
|
|
|
fragsize = skb->len + ihl;
|
|
|
|
if (fragsize > qp->q.max_size)
|
|
qp->q.max_size = fragsize;
|
|
|
|
if (ip_hdr(skb)->frag_off & htons(IP_DF) &&
|
|
fragsize > qp->max_df_size)
|
|
qp->max_df_size = fragsize;
|
|
|
|
if (qp->q.flags == (INET_FRAG_FIRST_IN | INET_FRAG_LAST_IN) &&
|
|
qp->q.meat == qp->q.len) {
|
|
unsigned long orefdst = skb->_skb_refdst;
|
|
|
|
skb->_skb_refdst = 0UL;
|
|
err = ip_frag_reasm(qp, prev, dev);
|
|
skb->_skb_refdst = orefdst;
|
|
return err;
|
|
}
|
|
|
|
skb_dst_drop(skb);
|
|
return -EINPROGRESS;
|
|
|
|
err:
|
|
kfree_skb(skb);
|
|
return err;
|
|
}
|
|
|
|
|
|
/* Build a new IP datagram from all its fragments. */
|
|
|
|
static int ip_frag_reasm(struct ipq *qp, struct sk_buff *prev,
|
|
struct net_device *dev)
|
|
{
|
|
struct net *net = container_of(qp->q.net, struct net, ipv4.frags);
|
|
struct iphdr *iph;
|
|
struct sk_buff *fp, *head = qp->q.fragments;
|
|
int len;
|
|
int ihlen;
|
|
int err;
|
|
int sum_truesize;
|
|
u8 ecn;
|
|
|
|
ipq_kill(qp);
|
|
|
|
ecn = ip_frag_ecn_table[qp->ecn];
|
|
if (unlikely(ecn == 0xff)) {
|
|
err = -EINVAL;
|
|
goto out_fail;
|
|
}
|
|
/* Make the one we just received the head. */
|
|
if (prev) {
|
|
head = prev->next;
|
|
fp = skb_clone(head, GFP_ATOMIC);
|
|
if (!fp)
|
|
goto out_nomem;
|
|
|
|
fp->next = head->next;
|
|
if (!fp->next)
|
|
qp->q.fragments_tail = fp;
|
|
prev->next = fp;
|
|
|
|
skb_morph(head, qp->q.fragments);
|
|
head->next = qp->q.fragments->next;
|
|
|
|
consume_skb(qp->q.fragments);
|
|
qp->q.fragments = head;
|
|
}
|
|
|
|
WARN_ON(!head);
|
|
WARN_ON(FRAG_CB(head)->offset != 0);
|
|
|
|
/* Allocate a new buffer for the datagram. */
|
|
ihlen = ip_hdrlen(head);
|
|
len = ihlen + qp->q.len;
|
|
|
|
err = -E2BIG;
|
|
if (len > 65535)
|
|
goto out_oversize;
|
|
|
|
/* Head of list must not be cloned. */
|
|
if (skb_unclone(head, GFP_ATOMIC))
|
|
goto out_nomem;
|
|
|
|
/* 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_nomem;
|
|
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 = 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;
|
|
add_frag_mem_limit(&qp->q, clone->truesize);
|
|
}
|
|
|
|
skb_push(head, head->data - skb_network_header(head));
|
|
|
|
sum_truesize = head->truesize;
|
|
for (fp = head->next; fp;) {
|
|
bool headstolen;
|
|
int delta;
|
|
struct sk_buff *next = fp->next;
|
|
|
|
sum_truesize += fp->truesize;
|
|
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);
|
|
|
|
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(&qp->q, sum_truesize);
|
|
|
|
head->next = NULL;
|
|
head->dev = dev;
|
|
head->tstamp = qp->q.stamp;
|
|
IPCB(head)->frag_max_size = max(qp->max_df_size, qp->q.max_size);
|
|
|
|
iph = ip_hdr(head);
|
|
iph->tot_len = htons(len);
|
|
iph->tos |= ecn;
|
|
|
|
/* When we set IP_DF on a refragmented skb we must also force a
|
|
* call to ip_fragment to avoid forwarding a DF-skb of size s while
|
|
* original sender only sent fragments of size f (where f < s).
|
|
*
|
|
* We only set DF/IPSKB_FRAG_PMTU if such DF fragment was the largest
|
|
* frag seen to avoid sending tiny DF-fragments in case skb was built
|
|
* from one very small df-fragment and one large non-df frag.
|
|
*/
|
|
if (qp->max_df_size == qp->q.max_size) {
|
|
IPCB(head)->flags |= IPSKB_FRAG_PMTU;
|
|
iph->frag_off = htons(IP_DF);
|
|
} else {
|
|
iph->frag_off = 0;
|
|
}
|
|
|
|
IP_INC_STATS_BH(net, IPSTATS_MIB_REASMOKS);
|
|
qp->q.fragments = NULL;
|
|
qp->q.fragments_tail = NULL;
|
|
return 0;
|
|
|
|
out_nomem:
|
|
net_dbg_ratelimited("queue_glue: no memory for gluing queue %p\n", qp);
|
|
err = -ENOMEM;
|
|
goto out_fail;
|
|
out_oversize:
|
|
net_info_ratelimited("Oversized IP packet from %pI4\n", &qp->saddr);
|
|
out_fail:
|
|
IP_INC_STATS_BH(net, IPSTATS_MIB_REASMFAILS);
|
|
return err;
|
|
}
|
|
|
|
/* Process an incoming IP datagram fragment. */
|
|
int ip_defrag(struct sk_buff *skb, u32 user)
|
|
{
|
|
struct ipq *qp;
|
|
struct net *net;
|
|
|
|
net = skb->dev ? dev_net(skb->dev) : dev_net(skb_dst(skb)->dev);
|
|
IP_INC_STATS_BH(net, IPSTATS_MIB_REASMREQDS);
|
|
|
|
/* Lookup (or create) queue header */
|
|
qp = ip_find(net, ip_hdr(skb), user);
|
|
if (qp) {
|
|
int ret;
|
|
|
|
spin_lock(&qp->q.lock);
|
|
|
|
ret = ip_frag_queue(qp, skb);
|
|
|
|
spin_unlock(&qp->q.lock);
|
|
ipq_put(qp);
|
|
return ret;
|
|
}
|
|
|
|
IP_INC_STATS_BH(net, IPSTATS_MIB_REASMFAILS);
|
|
kfree_skb(skb);
|
|
return -ENOMEM;
|
|
}
|
|
EXPORT_SYMBOL(ip_defrag);
|
|
|
|
struct sk_buff *ip_check_defrag(struct sk_buff *skb, u32 user)
|
|
{
|
|
struct iphdr iph;
|
|
int netoff;
|
|
u32 len;
|
|
|
|
if (skb->protocol != htons(ETH_P_IP))
|
|
return skb;
|
|
|
|
netoff = skb_network_offset(skb);
|
|
|
|
if (skb_copy_bits(skb, netoff, &iph, sizeof(iph)) < 0)
|
|
return skb;
|
|
|
|
if (iph.ihl < 5 || iph.version != 4)
|
|
return skb;
|
|
|
|
len = ntohs(iph.tot_len);
|
|
if (skb->len < netoff + len || len < (iph.ihl * 4))
|
|
return skb;
|
|
|
|
if (ip_is_fragment(&iph)) {
|
|
skb = skb_share_check(skb, GFP_ATOMIC);
|
|
if (skb) {
|
|
if (!pskb_may_pull(skb, netoff + iph.ihl * 4))
|
|
return skb;
|
|
if (pskb_trim_rcsum(skb, netoff + len))
|
|
return skb;
|
|
memset(IPCB(skb), 0, sizeof(struct inet_skb_parm));
|
|
if (ip_defrag(skb, user))
|
|
return NULL;
|
|
skb_clear_hash(skb);
|
|
}
|
|
}
|
|
return skb;
|
|
}
|
|
EXPORT_SYMBOL(ip_check_defrag);
|
|
|
|
#ifdef CONFIG_SYSCTL
|
|
static int zero;
|
|
|
|
static struct ctl_table ip4_frags_ns_ctl_table[] = {
|
|
{
|
|
.procname = "ipfrag_high_thresh",
|
|
.data = &init_net.ipv4.frags.high_thresh,
|
|
.maxlen = sizeof(int),
|
|
.mode = 0644,
|
|
.proc_handler = proc_dointvec_minmax,
|
|
.extra1 = &init_net.ipv4.frags.low_thresh
|
|
},
|
|
{
|
|
.procname = "ipfrag_low_thresh",
|
|
.data = &init_net.ipv4.frags.low_thresh,
|
|
.maxlen = sizeof(int),
|
|
.mode = 0644,
|
|
.proc_handler = proc_dointvec_minmax,
|
|
.extra1 = &zero,
|
|
.extra2 = &init_net.ipv4.frags.high_thresh
|
|
},
|
|
{
|
|
.procname = "ipfrag_time",
|
|
.data = &init_net.ipv4.frags.timeout,
|
|
.maxlen = sizeof(int),
|
|
.mode = 0644,
|
|
.proc_handler = proc_dointvec_jiffies,
|
|
},
|
|
{ }
|
|
};
|
|
|
|
/* secret interval has been deprecated */
|
|
static int ip4_frags_secret_interval_unused;
|
|
static struct ctl_table ip4_frags_ctl_table[] = {
|
|
{
|
|
.procname = "ipfrag_secret_interval",
|
|
.data = &ip4_frags_secret_interval_unused,
|
|
.maxlen = sizeof(int),
|
|
.mode = 0644,
|
|
.proc_handler = proc_dointvec_jiffies,
|
|
},
|
|
{
|
|
.procname = "ipfrag_max_dist",
|
|
.data = &sysctl_ipfrag_max_dist,
|
|
.maxlen = sizeof(int),
|
|
.mode = 0644,
|
|
.proc_handler = proc_dointvec_minmax,
|
|
.extra1 = &zero
|
|
},
|
|
{ }
|
|
};
|
|
|
|
static int __net_init ip4_frags_ns_ctl_register(struct net *net)
|
|
{
|
|
struct ctl_table *table;
|
|
struct ctl_table_header *hdr;
|
|
|
|
table = ip4_frags_ns_ctl_table;
|
|
if (!net_eq(net, &init_net)) {
|
|
table = kmemdup(table, sizeof(ip4_frags_ns_ctl_table), GFP_KERNEL);
|
|
if (!table)
|
|
goto err_alloc;
|
|
|
|
table[0].data = &net->ipv4.frags.high_thresh;
|
|
table[0].extra1 = &net->ipv4.frags.low_thresh;
|
|
table[0].extra2 = &init_net.ipv4.frags.high_thresh;
|
|
table[1].data = &net->ipv4.frags.low_thresh;
|
|
table[1].extra2 = &net->ipv4.frags.high_thresh;
|
|
table[2].data = &net->ipv4.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/ipv4", table);
|
|
if (!hdr)
|
|
goto err_reg;
|
|
|
|
net->ipv4.frags_hdr = hdr;
|
|
return 0;
|
|
|
|
err_reg:
|
|
if (!net_eq(net, &init_net))
|
|
kfree(table);
|
|
err_alloc:
|
|
return -ENOMEM;
|
|
}
|
|
|
|
static void __net_exit ip4_frags_ns_ctl_unregister(struct net *net)
|
|
{
|
|
struct ctl_table *table;
|
|
|
|
table = net->ipv4.frags_hdr->ctl_table_arg;
|
|
unregister_net_sysctl_table(net->ipv4.frags_hdr);
|
|
kfree(table);
|
|
}
|
|
|
|
static void __init ip4_frags_ctl_register(void)
|
|
{
|
|
register_net_sysctl(&init_net, "net/ipv4", ip4_frags_ctl_table);
|
|
}
|
|
#else
|
|
static int ip4_frags_ns_ctl_register(struct net *net)
|
|
{
|
|
return 0;
|
|
}
|
|
|
|
static void ip4_frags_ns_ctl_unregister(struct net *net)
|
|
{
|
|
}
|
|
|
|
static void __init ip4_frags_ctl_register(void)
|
|
{
|
|
}
|
|
#endif
|
|
|
|
static int __net_init ipv4_frags_init_net(struct net *net)
|
|
{
|
|
/* Fragment cache limits.
|
|
*
|
|
* The fragment memory accounting code, (tries to) account for
|
|
* the real memory usage, by measuring both the size of frag
|
|
* queue struct (inet_frag_queue (ipv4:ipq/ipv6:frag_queue))
|
|
* and the SKB's truesize.
|
|
*
|
|
* A 64K fragment consumes 129736 bytes (44*2944)+200
|
|
* (1500 truesize == 2944, sizeof(struct ipq) == 200)
|
|
*
|
|
* We will commit 4MB at one time. Should we cross that limit
|
|
* we will prune down to 3MB, making room for approx 8 big 64K
|
|
* fragments 8x128k.
|
|
*/
|
|
net->ipv4.frags.high_thresh = 4 * 1024 * 1024;
|
|
net->ipv4.frags.low_thresh = 3 * 1024 * 1024;
|
|
/*
|
|
* Important NOTE! Fragment queue must be destroyed before MSL expires.
|
|
* RFC791 is wrong proposing to prolongate timer each fragment arrival
|
|
* by TTL.
|
|
*/
|
|
net->ipv4.frags.timeout = IP_FRAG_TIME;
|
|
|
|
inet_frags_init_net(&net->ipv4.frags);
|
|
|
|
return ip4_frags_ns_ctl_register(net);
|
|
}
|
|
|
|
static void __net_exit ipv4_frags_exit_net(struct net *net)
|
|
{
|
|
ip4_frags_ns_ctl_unregister(net);
|
|
inet_frags_exit_net(&net->ipv4.frags, &ip4_frags);
|
|
}
|
|
|
|
static struct pernet_operations ip4_frags_ops = {
|
|
.init = ipv4_frags_init_net,
|
|
.exit = ipv4_frags_exit_net,
|
|
};
|
|
|
|
void __init ipfrag_init(void)
|
|
{
|
|
ip4_frags_ctl_register();
|
|
register_pernet_subsys(&ip4_frags_ops);
|
|
ip4_frags.hashfn = ip4_hashfn;
|
|
ip4_frags.constructor = ip4_frag_init;
|
|
ip4_frags.destructor = ip4_frag_free;
|
|
ip4_frags.skb_free = NULL;
|
|
ip4_frags.qsize = sizeof(struct ipq);
|
|
ip4_frags.match = ip4_frag_match;
|
|
ip4_frags.frag_expire = ip_expire;
|
|
ip4_frags.frags_cache_name = ip_frag_cache_name;
|
|
if (inet_frags_init(&ip4_frags))
|
|
panic("IP: failed to allocate ip4_frags cache\n");
|
|
}
|