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Diffstat (limited to 'net/ipv4/ip_fragment.c')
-rw-r--r--net/ipv4/ip_fragment.c360
1 files changed, 222 insertions, 138 deletions
diff --git a/net/ipv4/ip_fragment.c b/net/ipv4/ip_fragment.c
index d14d741fb05e..88281fbce88c 100644
--- a/net/ipv4/ip_fragment.c
+++ b/net/ipv4/ip_fragment.c
@@ -57,6 +57,57 @@
*/
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;
@@ -75,8 +126,8 @@ static u8 ip4_frag_ecn(u8 tos)
static struct inet_frags ip4_frags;
-static int ip_frag_reasm(struct ipq *qp, struct sk_buff *prev,
- struct net_device *dev);
+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)
@@ -136,7 +187,7 @@ 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;
+ struct sk_buff *head = NULL;
struct net *net;
struct ipq *qp;
int err;
@@ -152,14 +203,36 @@ static void ip_expire(struct timer_list *t)
ipq_kill(qp);
__IP_INC_STATS(net, IPSTATS_MIB_REASMFAILS);
-
- head = qp->q.fragments;
-
__IP_INC_STATS(net, IPSTATS_MIB_REASMTIMEOUT);
- if (!(qp->q.flags & INET_FRAG_FIRST_IN) || !head)
+ 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;
@@ -179,16 +252,16 @@ static void ip_expire(struct timer_list *t)
(skb_rtable(head)->rt_type != RTN_LOCAL))
goto out;
- skb_get(head);
spin_unlock(&qp->q.lock);
icmp_send(head, ICMP_TIME_EXCEEDED, ICMP_EXC_FRAGTIME, 0);
- kfree_skb(head);
goto out_rcu_unlock;
out:
spin_unlock(&qp->q.lock);
out_rcu_unlock:
rcu_read_unlock();
+ if (head)
+ kfree_skb(head);
ipq_put(qp);
}
@@ -231,7 +304,7 @@ static int ip_frag_too_far(struct ipq *qp)
end = atomic_inc_return(&peer->rid);
qp->rid = end;
- rc = qp->q.fragments && (end - start) > max;
+ rc = qp->q.fragments_tail && (end - start) > max;
if (rc) {
struct net *net;
@@ -245,7 +318,6 @@ static int ip_frag_too_far(struct ipq *qp)
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)) {
@@ -253,21 +325,16 @@ static int ip_frag_reinit(struct ipq *qp)
return -ETIMEDOUT;
}
- fp = qp->q.fragments;
- do {
- struct sk_buff *xp = fp->next;
-
- sum_truesize += fp->truesize;
- kfree_skb(fp);
- fp = xp;
- } while (fp);
+ 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;
@@ -277,7 +344,9 @@ static int ip_frag_reinit(struct ipq *qp)
/* 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 *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;
@@ -340,100 +409,61 @@ static int ip_frag_queue(struct ipq *qp, struct sk_buff *skb)
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 || prev->ip_defrag_offset < offset) {
- next = NULL;
- goto found;
- }
- prev = NULL;
- for (next = qp->q.fragments; next != NULL; next = next->next) {
- if (next->ip_defrag_offset >= offset)
- break; /* bingo! */
- prev = next;
- }
+ /* Note : skb->rbnode and skb->dev share the same location. */
+ dev = skb->dev;
+ /* Makes sure compiler wont do silly aliasing games */
+ barrier();
-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.
+ /* 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).
*/
- if (prev) {
- int i = (prev->ip_defrag_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 && next->ip_defrag_offset < end) {
- int i = end - next->ip_defrag_offset; /* overlap is 'i' bytes */
-
- if (i < next->len) {
- int delta = -next->truesize;
-
- /* Eat head of the next overlapped fragment
- * and leave the loop. The next ones cannot overlap.
- */
- if (!pskb_pull(next, i))
- goto err;
- delta += next->truesize;
- if (delta)
- add_frag_mem_limit(qp->q.net, delta);
- next->ip_defrag_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.net, free_it->truesize);
- kfree_skb(free_it);
- }
+ /* 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 discard_qp;
+ 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 discard_qp;
+ } 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);
}
- /* Note : skb->ip_defrag_offset and skb->dev share the same location */
- dev = skb->dev;
if (dev)
qp->iif = dev->ifindex;
- /* Makes sure compiler wont do silly aliasing games */
- barrier();
skb->ip_defrag_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;
-
qp->q.stamp = skb->tstamp;
qp->q.meat += skb->len;
qp->ecn |= ecn;
@@ -455,7 +485,7 @@ found:
unsigned long orefdst = skb->_skb_refdst;
skb->_skb_refdst = 0UL;
- err = ip_frag_reasm(qp, prev, dev);
+ err = ip_frag_reasm(qp, skb, prev_tail, dev);
skb->_skb_refdst = orefdst;
return err;
}
@@ -463,20 +493,24 @@ found:
skb_dst_drop(skb);
return -EINPROGRESS;
+discard_qp:
+ inet_frag_kill(&qp->q);
+ err = -EINVAL;
+ __IP_INC_STATS(net, IPSTATS_MIB_REASM_OVERLAPS);
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)
+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 = qp->q.fragments;
+ 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;
@@ -490,25 +524,26 @@ static int ip_frag_reasm(struct ipq *qp, struct sk_buff *prev,
goto out_fail;
}
/* Make the one we just received the head. */
- if (prev) {
- head = prev->next;
- fp = skb_clone(head, GFP_ATOMIC);
+ if (head != skb) {
+ fp = skb_clone(skb, GFP_ATOMIC);
if (!fp)
goto out_nomem;
-
- fp->next = head->next;
- if (!fp->next)
+ 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;
- prev->next = fp;
-
- skb_morph(head, qp->q.fragments);
- head->next = qp->q.fragments->next;
-
- consume_skb(qp->q.fragments);
- qp->q.fragments = head;
+ 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);
WARN_ON(head->ip_defrag_offset != 0);
/* Allocate a new buffer for the datagram. */
@@ -533,35 +568,60 @@ static int ip_frag_reasm(struct ipq *qp, struct sk_buff *prev,
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;
+ 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_shinfo(head)->frag_list = head->next;
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;
+ /* 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));
+ 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;
head->next = NULL;
+ 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);
@@ -589,7 +649,9 @@ static int ip_frag_reasm(struct ipq *qp, struct sk_buff *prev,
__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:
@@ -671,6 +733,28 @@ 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;
generated by cgit v1.2.3-58-ga151 (git 2.39.0) at 2024-12-28 03:00:47 +0000