linux_dsm_epyc7002/net/ipv4/ip_fragment.c
Peter Oskolkov 8361962392 net/ipfrag: let ip[6]frag_high_thresh in ns be higher than in init_net
Currently, ip[6]frag_high_thresh sysctl values in new namespaces are
hard-limited to those of the root/init ns.

There are at least two use cases when it would be desirable to
set the high_thresh values higher in a child namespace vs the global hard
limit:

- a security/ddos protection policy may lower the thresholds in the
  root/init ns but allow for a special exception in a child namespace
- testing: a test running in a namespace may want to set these
  thresholds higher in its namespace than what is in the root/init ns

The new behavior:

 # ip netns add testns
 # ip netns exec testns bash

 # sysctl -w net.ipv4.ipfrag_high_thresh=9000000
 net.ipv4.ipfrag_high_thresh = 9000000

 # sysctl net.ipv4.ipfrag_high_thresh
 net.ipv4.ipfrag_high_thresh = 9000000

 # sysctl -w net.ipv6.ip6frag_high_thresh=9000000
 net.ipv6.ip6frag_high_thresh = 9000000

 # sysctl net.ipv6.ip6frag_high_thresh
 net.ipv6.ip6frag_high_thresh = 9000000

The old behavior:

 # ip netns add testns
 # ip netns exec testns bash

 # sysctl -w net.ipv4.ipfrag_high_thresh=9000000
 net.ipv4.ipfrag_high_thresh = 9000000

 # sysctl net.ipv4.ipfrag_high_thresh
 net.ipv4.ipfrag_high_thresh = 4194304

 # sysctl -w net.ipv6.ip6frag_high_thresh=9000000
 net.ipv6.ip6frag_high_thresh = 9000000

 # sysctl net.ipv6.ip6frag_high_thresh
 net.ipv6.ip6frag_high_thresh = 4194304

Signed-off-by: Peter Oskolkov <posk@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2018-09-21 19:45:52 -07:00

969 lines
24 KiB
C

// SPDX-License-Identifier: GPL-2.0
/*
* 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>
#include <net/l3mdev.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 const char ip_frag_cache_name[] = "ip4-frags";
/* Use skb->cb to track consecutive/adjacent fragments coming at
* the end of the queue. Nodes in the rb-tree queue will
* contain "runs" of one or more adjacent fragments.
*
* Invariants:
* - next_frag is NULL at the tail of a "run";
* - the head of a "run" has the sum of all fragment lengths in frag_run_len.
*/
struct ipfrag_skb_cb {
struct inet_skb_parm h;
struct sk_buff *next_frag;
int frag_run_len;
};
#define FRAG_CB(skb) ((struct ipfrag_skb_cb *)((skb)->cb))
static void ip4_frag_init_run(struct sk_buff *skb)
{
BUILD_BUG_ON(sizeof(struct ipfrag_skb_cb) > sizeof(skb->cb));
FRAG_CB(skb)->next_frag = NULL;
FRAG_CB(skb)->frag_run_len = skb->len;
}
/* Append skb to the last "run". */
static void ip4_frag_append_to_last_run(struct inet_frag_queue *q,
struct sk_buff *skb)
{
RB_CLEAR_NODE(&skb->rbnode);
FRAG_CB(skb)->next_frag = NULL;
FRAG_CB(q->last_run_head)->frag_run_len += skb->len;
FRAG_CB(q->fragments_tail)->next_frag = skb;
q->fragments_tail = skb;
}
/* Create a new "run" with the skb. */
static void ip4_frag_create_run(struct inet_frag_queue *q, struct sk_buff *skb)
{
if (q->last_run_head)
rb_link_node(&skb->rbnode, &q->last_run_head->rbnode,
&q->last_run_head->rbnode.rb_right);
else
rb_link_node(&skb->rbnode, NULL, &q->rb_fragments.rb_node);
rb_insert_color(&skb->rbnode, &q->rb_fragments);
ip4_frag_init_run(skb);
q->fragments_tail = skb;
q->last_run_head = skb;
}
/* Describe an entry in the "incomplete datagrams" queue. */
struct ipq {
struct inet_frag_queue q;
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;
static int ip_frag_reasm(struct ipq *qp, struct sk_buff *skb,
struct sk_buff *prev_tail, struct net_device *dev);
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 frag_v4_compare_key *key = a;
q->key.v4 = *key;
qp->ecn = 0;
qp->peer = q->net->max_dist ?
inet_getpeer_v4(net->ipv4.peers, key->saddr, key->vif, 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);
}
/* 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);
}
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(struct timer_list *t)
{
struct inet_frag_queue *frag = from_timer(frag, t, timer);
const struct iphdr *iph;
struct sk_buff *head = NULL;
struct net *net;
struct ipq *qp;
int err;
qp = container_of(frag, struct ipq, q);
net = container_of(qp->q.net, struct net, ipv4.frags);
rcu_read_lock();
spin_lock(&qp->q.lock);
if (qp->q.flags & INET_FRAG_COMPLETE)
goto out;
ipq_kill(qp);
__IP_INC_STATS(net, IPSTATS_MIB_REASMFAILS);
__IP_INC_STATS(net, IPSTATS_MIB_REASMTIMEOUT);
if (!(qp->q.flags & INET_FRAG_FIRST_IN))
goto out;
/* sk_buff::dev and sk_buff::rbnode are unionized. So we
* pull the head out of the tree in order to be able to
* deal with head->dev.
*/
if (qp->q.fragments) {
head = qp->q.fragments;
qp->q.fragments = head->next;
} else {
head = skb_rb_first(&qp->q.rb_fragments);
if (!head)
goto out;
if (FRAG_CB(head)->next_frag)
rb_replace_node(&head->rbnode,
&FRAG_CB(head)->next_frag->rbnode,
&qp->q.rb_fragments);
else
rb_erase(&head->rbnode, &qp->q.rb_fragments);
memset(&head->rbnode, 0, sizeof(head->rbnode));
barrier();
}
if (head == qp->q.fragments_tail)
qp->q.fragments_tail = NULL;
sub_frag_mem_limit(qp->q.net, head->truesize);
head->dev = dev_get_by_index_rcu(net, qp->iif);
if (!head->dev)
goto out;
/* 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;
/* Only an end host needs to send an ICMP
* "Fragment Reassembly Timeout" message, per RFC792.
*/
if (frag_expire_skip_icmp(qp->q.key.v4.user) &&
(skb_rtable(head)->rt_type != RTN_LOCAL))
goto out;
spin_unlock(&qp->q.lock);
icmp_send(head, ICMP_TIME_EXCEEDED, ICMP_EXC_FRAGTIME, 0);
goto out_rcu_unlock;
out:
spin_unlock(&qp->q.lock);
out_rcu_unlock:
rcu_read_unlock();
kfree_skb(head);
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, int vif)
{
struct frag_v4_compare_key key = {
.saddr = iph->saddr,
.daddr = iph->daddr,
.user = user,
.vif = vif,
.id = iph->id,
.protocol = iph->protocol,
};
struct inet_frag_queue *q;
q = inet_frag_find(&net->ipv4.frags, &key);
if (!q)
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 = qp->q.net->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_tail && (end - start) > max;
if (rc) {
struct net *net;
net = container_of(qp->q.net, struct net, ipv4.frags);
__IP_INC_STATS(net, IPSTATS_MIB_REASMFAILS);
}
return rc;
}
static int ip_frag_reinit(struct ipq *qp)
{
unsigned int sum_truesize = 0;
if (!mod_timer(&qp->q.timer, jiffies + qp->q.net->timeout)) {
refcount_inc(&qp->q.refcnt);
return -ETIMEDOUT;
}
sum_truesize = inet_frag_rbtree_purge(&qp->q.rb_fragments);
sub_frag_mem_limit(qp->q.net, sum_truesize);
qp->q.flags = 0;
qp->q.len = 0;
qp->q.meat = 0;
qp->q.fragments = NULL;
qp->q.rb_fragments = RB_ROOT;
qp->q.fragments_tail = NULL;
qp->q.last_run_head = 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 net *net = container_of(qp->q.net, struct net, ipv4.frags);
struct rb_node **rbn, *parent;
struct sk_buff *skb1, *prev_tail;
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 - skb_network_offset(skb) - 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 discard_qp;
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 discard_qp;
qp->q.len = end;
}
}
if (end == offset)
goto discard_qp;
err = -ENOMEM;
if (!pskb_pull(skb, skb_network_offset(skb) + ihl))
goto discard_qp;
err = pskb_trim_rcsum(skb, end - offset);
if (err)
goto discard_qp;
/* Note : skb->rbnode and skb->dev share the same location. */
dev = skb->dev;
/* Makes sure compiler wont do silly aliasing games */
barrier();
/* RFC5722, Section 4, amended by Errata ID : 3089
* 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) MUST be silently discarded.
*
* We do the same here for IPv4 (and increment an snmp counter).
*/
err = -EINVAL;
/* Find out where to put this fragment. */
prev_tail = qp->q.fragments_tail;
if (!prev_tail)
ip4_frag_create_run(&qp->q, skb); /* First fragment. */
else if (prev_tail->ip_defrag_offset + prev_tail->len < end) {
/* This is the common case: skb goes to the end. */
/* Detect and discard overlaps. */
if (offset < prev_tail->ip_defrag_offset + prev_tail->len)
goto overlap;
if (offset == prev_tail->ip_defrag_offset + prev_tail->len)
ip4_frag_append_to_last_run(&qp->q, skb);
else
ip4_frag_create_run(&qp->q, skb);
} else {
/* Binary search. Note that skb can become the first fragment,
* but not the last (covered above).
*/
rbn = &qp->q.rb_fragments.rb_node;
do {
parent = *rbn;
skb1 = rb_to_skb(parent);
if (end <= skb1->ip_defrag_offset)
rbn = &parent->rb_left;
else if (offset >= skb1->ip_defrag_offset +
FRAG_CB(skb1)->frag_run_len)
rbn = &parent->rb_right;
else /* Found an overlap with skb1. */
goto overlap;
} while (*rbn);
/* Here we have parent properly set, and rbn pointing to
* one of its NULL left/right children. Insert skb.
*/
ip4_frag_init_run(skb);
rb_link_node(&skb->rbnode, parent, rbn);
rb_insert_color(&skb->rbnode, &qp->q.rb_fragments);
}
if (dev)
qp->iif = dev->ifindex;
skb->ip_defrag_offset = offset;
qp->q.stamp = skb->tstamp;
qp->q.meat += skb->len;
qp->ecn |= ecn;
add_frag_mem_limit(qp->q.net, 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, skb, prev_tail, dev);
skb->_skb_refdst = orefdst;
if (err)
inet_frag_kill(&qp->q);
return err;
}
skb_dst_drop(skb);
return -EINPROGRESS;
overlap:
__IP_INC_STATS(net, IPSTATS_MIB_REASM_OVERLAPS);
discard_qp:
inet_frag_kill(&qp->q);
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 *skb,
struct sk_buff *prev_tail, struct net_device *dev)
{
struct net *net = container_of(qp->q.net, struct net, ipv4.frags);
struct iphdr *iph;
struct sk_buff *fp, *head = skb_rb_first(&qp->q.rb_fragments);
struct sk_buff **nextp; /* To build frag_list. */
struct rb_node *rbn;
int len;
int ihlen;
int err;
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 (head != skb) {
fp = skb_clone(skb, GFP_ATOMIC);
if (!fp)
goto out_nomem;
FRAG_CB(fp)->next_frag = FRAG_CB(skb)->next_frag;
if (RB_EMPTY_NODE(&skb->rbnode))
FRAG_CB(prev_tail)->next_frag = fp;
else
rb_replace_node(&skb->rbnode, &fp->rbnode,
&qp->q.rb_fragments);
if (qp->q.fragments_tail == skb)
qp->q.fragments_tail = fp;
skb_morph(skb, head);
FRAG_CB(skb)->next_frag = FRAG_CB(head)->next_frag;
rb_replace_node(&head->rbnode, &skb->rbnode,
&qp->q.rb_fragments);
consume_skb(head);
head = skb;
}
WARN_ON(head->ip_defrag_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;
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->truesize += clone->truesize;
clone->csum = 0;
clone->ip_summed = head->ip_summed;
add_frag_mem_limit(qp->q.net, clone->truesize);
skb_shinfo(head)->frag_list = clone;
nextp = &clone->next;
} else {
nextp = &skb_shinfo(head)->frag_list;
}
skb_push(head, head->data - skb_network_header(head));
/* Traverse the tree in order, to build frag_list. */
fp = FRAG_CB(head)->next_frag;
rbn = rb_next(&head->rbnode);
rb_erase(&head->rbnode, &qp->q.rb_fragments);
while (rbn || fp) {
/* fp points to the next sk_buff in the current run;
* rbn points to the next run.
*/
/* Go through the current run. */
while (fp) {
*nextp = fp;
nextp = &fp->next;
fp->prev = NULL;
memset(&fp->rbnode, 0, sizeof(fp->rbnode));
fp->sk = NULL;
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;
fp = FRAG_CB(fp)->next_frag;
}
/* Move to the next run. */
if (rbn) {
struct rb_node *rbnext = rb_next(rbn);
fp = rb_to_skb(rbn);
rb_erase(rbn, &qp->q.rb_fragments);
rbn = rbnext;
}
}
sub_frag_mem_limit(qp->q.net, head->truesize);
*nextp = NULL;
skb_mark_not_on_list(head);
head->prev = 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_send_check(iph);
__IP_INC_STATS(net, IPSTATS_MIB_REASMOKS);
qp->q.fragments = NULL;
qp->q.rb_fragments = RB_ROOT;
qp->q.fragments_tail = NULL;
qp->q.last_run_head = 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->q.key.v4.saddr);
out_fail:
__IP_INC_STATS(net, IPSTATS_MIB_REASMFAILS);
return err;
}
/* Process an incoming IP datagram fragment. */
int ip_defrag(struct net *net, struct sk_buff *skb, u32 user)
{
struct net_device *dev = skb->dev ? : skb_dst(skb)->dev;
int vif = l3mdev_master_ifindex_rcu(dev);
struct ipq *qp;
__IP_INC_STATS(net, IPSTATS_MIB_REASMREQDS);
skb_orphan(skb);
/* Lookup (or create) queue header */
qp = ip_find(net, ip_hdr(skb), user, vif);
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(net, IPSTATS_MIB_REASMFAILS);
kfree_skb(skb);
return -ENOMEM;
}
EXPORT_SYMBOL(ip_defrag);
struct sk_buff *ip_check_defrag(struct net *net, 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(net, skb, user))
return NULL;
skb_clear_hash(skb);
}
}
return skb;
}
EXPORT_SYMBOL(ip_check_defrag);
unsigned int inet_frag_rbtree_purge(struct rb_root *root)
{
struct rb_node *p = rb_first(root);
unsigned int sum = 0;
while (p) {
struct sk_buff *skb = rb_entry(p, struct sk_buff, rbnode);
p = rb_next(p);
rb_erase(&skb->rbnode, root);
while (skb) {
struct sk_buff *next = FRAG_CB(skb)->next_frag;
sum += skb->truesize;
kfree_skb(skb);
skb = next;
}
}
return sum;
}
EXPORT_SYMBOL(inet_frag_rbtree_purge);
#ifdef CONFIG_SYSCTL
static int dist_min;
static struct ctl_table ip4_frags_ns_ctl_table[] = {
{
.procname = "ipfrag_high_thresh",
.data = &init_net.ipv4.frags.high_thresh,
.maxlen = sizeof(unsigned long),
.mode = 0644,
.proc_handler = proc_doulongvec_minmax,
.extra1 = &init_net.ipv4.frags.low_thresh
},
{
.procname = "ipfrag_low_thresh",
.data = &init_net.ipv4.frags.low_thresh,
.maxlen = sizeof(unsigned long),
.mode = 0644,
.proc_handler = proc_doulongvec_minmax,
.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,
},
{
.procname = "ipfrag_max_dist",
.data = &init_net.ipv4.frags.max_dist,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = proc_dointvec_minmax,
.extra1 = &dist_min,
},
{ }
};
/* 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,
},
{ }
};
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[1].data = &net->ipv4.frags.low_thresh;
table[1].extra2 = &net->ipv4.frags.high_thresh;
table[2].data = &net->ipv4.frags.timeout;
table[3].data = &net->ipv4.frags.max_dist;
}
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)
{
int res;
/* 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;
net->ipv4.frags.max_dist = 64;
net->ipv4.frags.f = &ip4_frags;
res = inet_frags_init_net(&net->ipv4.frags);
if (res < 0)
return res;
res = ip4_frags_ns_ctl_register(net);
if (res < 0)
inet_frags_exit_net(&net->ipv4.frags);
return res;
}
static void __net_exit ipv4_frags_exit_net(struct net *net)
{
ip4_frags_ns_ctl_unregister(net);
inet_frags_exit_net(&net->ipv4.frags);
}
static struct pernet_operations ip4_frags_ops = {
.init = ipv4_frags_init_net,
.exit = ipv4_frags_exit_net,
};
static u32 ip4_key_hashfn(const void *data, u32 len, u32 seed)
{
return jhash2(data,
sizeof(struct frag_v4_compare_key) / sizeof(u32), seed);
}
static u32 ip4_obj_hashfn(const void *data, u32 len, u32 seed)
{
const struct inet_frag_queue *fq = data;
return jhash2((const u32 *)&fq->key.v4,
sizeof(struct frag_v4_compare_key) / sizeof(u32), seed);
}
static int ip4_obj_cmpfn(struct rhashtable_compare_arg *arg, const void *ptr)
{
const struct frag_v4_compare_key *key = arg->key;
const struct inet_frag_queue *fq = ptr;
return !!memcmp(&fq->key, key, sizeof(*key));
}
static const struct rhashtable_params ip4_rhash_params = {
.head_offset = offsetof(struct inet_frag_queue, node),
.key_offset = offsetof(struct inet_frag_queue, key),
.key_len = sizeof(struct frag_v4_compare_key),
.hashfn = ip4_key_hashfn,
.obj_hashfn = ip4_obj_hashfn,
.obj_cmpfn = ip4_obj_cmpfn,
.automatic_shrinking = true,
};
void __init ipfrag_init(void)
{
ip4_frags.constructor = ip4_frag_init;
ip4_frags.destructor = ip4_frag_free;
ip4_frags.qsize = sizeof(struct ipq);
ip4_frags.frag_expire = ip_expire;
ip4_frags.frags_cache_name = ip_frag_cache_name;
ip4_frags.rhash_params = ip4_rhash_params;
if (inet_frags_init(&ip4_frags))
panic("IP: failed to allocate ip4_frags cache\n");
ip4_frags_ctl_register();
register_pernet_subsys(&ip4_frags_ops);
}