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authorPeter Oskolkov <posk@google.com>2019-01-22 10:02:50 -0800
committerDavid S. Miller <davem@davemloft.net>2019-01-25 21:37:11 -0800
commitc23f35d19db3b36ffb9e04b08f1d91565d15f84f (patch)
treedda4eb1a696a0aad31742ae8c1f0bc3d6ca72472 /net/ipv4/ip_fragment.c
parentMerge branch 's390-qeth-next' (diff)
downloadlinux-dev-c23f35d19db3b36ffb9e04b08f1d91565d15f84f.tar.xz
linux-dev-c23f35d19db3b36ffb9e04b08f1d91565d15f84f.zip
net: IP defrag: encapsulate rbtree defrag code into callable functions
This is a refactoring patch: without changing runtime behavior, it moves rbtree-related code from IPv4-specific files/functions into .h/.c defrag files shared with IPv6 defragmentation code. Signed-off-by: Peter Oskolkov <posk@google.com> Cc: Eric Dumazet <edumazet@google.com> Cc: Florian Westphal <fw@strlen.de> Cc: Tom Herbert <tom@herbertland.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4/ip_fragment.c')
-rw-r--r--net/ipv4/ip_fragment.c289
1 files changed, 27 insertions, 262 deletions
diff --git a/net/ipv4/ip_fragment.c b/net/ipv4/ip_fragment.c
index 867be8f7f1fa..486ecb0aeb87 100644
--- a/net/ipv4/ip_fragment.c
+++ b/net/ipv4/ip_fragment.c
@@ -57,57 +57,6 @@
*/
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;
@@ -212,27 +161,9 @@ static void ip_expire(struct timer_list *t)
* 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 = inet_frag_pull_head(&qp->q);
+ if (!head)
+ goto out;
head->dev = dev_get_by_index_rcu(net, qp->iif);
if (!head->dev)
goto out;
@@ -344,12 +275,10 @@ static int ip_frag_reinit(struct ipq *qp)
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;
- int ihl, end, skb1_run_end;
+ int ihl, end, flags, offset;
+ struct sk_buff *prev_tail;
struct net_device *dev;
unsigned int fragsize;
- int flags, offset;
int err = -ENOENT;
u8 ecn;
@@ -413,62 +342,13 @@ static int ip_frag_queue(struct ipq *qp, struct sk_buff *skb)
/* 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) but
- * we do not want to drop the whole queue in response to a duplicate
- * fragment.
- */
-
- 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);
- skb1_run_end = skb1->ip_defrag_offset +
- FRAG_CB(skb1)->frag_run_len;
- if (end <= skb1->ip_defrag_offset)
- rbn = &parent->rb_left;
- else if (offset >= skb1_run_end)
- rbn = &parent->rb_right;
- else if (offset >= skb1->ip_defrag_offset &&
- end <= skb1_run_end)
- goto err; /* No new data, potential duplicate */
- else
- goto overlap; /* Found an 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);
- }
+ err = inet_frag_queue_insert(&qp->q, skb, offset, end);
+ if (err)
+ goto insert_error;
if (dev)
qp->iif = dev->ifindex;
- skb->ip_defrag_offset = offset;
qp->q.stamp = skb->tstamp;
qp->q.meat += skb->len;
@@ -501,10 +381,16 @@ static int ip_frag_queue(struct ipq *qp, struct sk_buff *skb)
skb_dst_drop(skb);
return -EINPROGRESS;
-overlap:
+insert_error:
+ if (err == IPFRAG_DUP) {
+ kfree_skb(skb);
+ return -EINVAL;
+ }
+ err = -EINVAL;
__IP_INC_STATS(net, IPSTATS_MIB_REASM_OVERLAPS);
discard_qp:
inet_frag_kill(&qp->q);
+ __IP_INC_STATS(net, IPSTATS_MIB_REASMFAILS);
err:
kfree_skb(skb);
return err;
@@ -516,13 +402,8 @@ static int ip_frag_reasm(struct ipq *qp, struct sk_buff *skb,
{
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 delta;
- int err;
+ void *reasm_data;
+ int len, err;
u8 ecn;
ipq_kill(qp);
@@ -532,117 +413,23 @@ static int ip_frag_reasm(struct ipq *qp, struct sk_buff *skb,
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;
+ /* Make the one we just received the head. */
+ reasm_data = inet_frag_reasm_prepare(&qp->q, skb, prev_tail);
+ if (!reasm_data)
+ goto out_nomem;
+ len = ip_hdrlen(skb) + qp->q.len;
err = -E2BIG;
if (len > 65535)
goto out_oversize;
- delta = - head->truesize;
-
- /* Head of list must not be cloned. */
- if (skb_unclone(head, GFP_ATOMIC))
- goto out_nomem;
-
- delta += head->truesize;
- if (delta)
- add_frag_mem_limit(qp->q.net, delta);
-
- /* 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));
+ inet_frag_reasm_finish(&qp->q, skb, reasm_data);
- /* 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);
+ skb->dev = dev;
+ IPCB(skb)->frag_max_size = max(qp->max_df_size, qp->q.max_size);
- iph = ip_hdr(head);
+ iph = ip_hdr(skb);
iph->tot_len = htons(len);
iph->tos |= ecn;
@@ -655,7 +442,7 @@ static int ip_frag_reasm(struct ipq *qp, struct sk_buff *skb,
* 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;
+ IPCB(skb)->flags |= IPSKB_FRAG_PMTU;
iph->frag_off = htons(IP_DF);
} else {
iph->frag_off = 0;
@@ -753,28 +540,6 @@ struct sk_buff *ip_check_defrag(struct net *net, struct sk_buff *skb, u32 user)
}
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;