Linux-2.6.12-rc2
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.
Let it rip!
diff --git a/net/ipv4/ip_fragment.c b/net/ipv4/ip_fragment.c
new file mode 100644
index 0000000..7f68e27
--- /dev/null
+++ b/net/ipv4/ip_fragment.c
@@ -0,0 +1,691 @@
+/*
+ * 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.
+ *
+ * Version: $Id: ip_fragment.c,v 1.59 2002/01/12 07:54:56 davem Exp $
+ *
+ * Authors: Fred N. van Kempen <waltje@uWalt.NL.Mugnet.ORG>
+ * Alan Cox <Alan.Cox@linux.org>
+ *
+ * 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.
+ */
+
+#include <linux/config.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 <net/sock.h>
+#include <net/ip.h>
+#include <net/icmp.h>
+#include <net/checksum.h>
+#include <linux/tcp.h>
+#include <linux/udp.h>
+#include <linux/inet.h>
+#include <linux/netfilter_ipv4.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
+ */
+
+/* Fragment cache limits. We will commit 256K at one time. Should we
+ * cross that limit we will prune down to 192K. This should cope with
+ * even the most extreme cases without allowing an attacker to measurably
+ * harm machine performance.
+ */
+int sysctl_ipfrag_high_thresh = 256*1024;
+int sysctl_ipfrag_low_thresh = 192*1024;
+
+/* Important NOTE! Fragment queue must be destroyed before MSL expires.
+ * RFC791 is wrong proposing to prolongate timer each fragment arrival by TTL.
+ */
+int sysctl_ipfrag_time = IP_FRAG_TIME;
+
+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 ipq *next; /* linked list pointers */
+ struct list_head lru_list; /* lru list member */
+ u32 user;
+ u32 saddr;
+ u32 daddr;
+ u16 id;
+ u8 protocol;
+ u8 last_in;
+#define COMPLETE 4
+#define FIRST_IN 2
+#define LAST_IN 1
+
+ struct sk_buff *fragments; /* linked list of received fragments */
+ int len; /* total length of original datagram */
+ int meat;
+ spinlock_t lock;
+ atomic_t refcnt;
+ struct timer_list timer; /* when will this queue expire? */
+ struct ipq **pprev;
+ int iif;
+ struct timeval stamp;
+};
+
+/* Hash table. */
+
+#define IPQ_HASHSZ 64
+
+/* Per-bucket lock is easy to add now. */
+static struct ipq *ipq_hash[IPQ_HASHSZ];
+static DEFINE_RWLOCK(ipfrag_lock);
+static u32 ipfrag_hash_rnd;
+static LIST_HEAD(ipq_lru_list);
+int ip_frag_nqueues = 0;
+
+static __inline__ void __ipq_unlink(struct ipq *qp)
+{
+ if(qp->next)
+ qp->next->pprev = qp->pprev;
+ *qp->pprev = qp->next;
+ list_del(&qp->lru_list);
+ ip_frag_nqueues--;
+}
+
+static __inline__ void ipq_unlink(struct ipq *ipq)
+{
+ write_lock(&ipfrag_lock);
+ __ipq_unlink(ipq);
+ write_unlock(&ipfrag_lock);
+}
+
+static unsigned int ipqhashfn(u16 id, u32 saddr, u32 daddr, u8 prot)
+{
+ return jhash_3words((u32)id << 16 | prot, saddr, daddr,
+ ipfrag_hash_rnd) & (IPQ_HASHSZ - 1);
+}
+
+static struct timer_list ipfrag_secret_timer;
+int sysctl_ipfrag_secret_interval = 10 * 60 * HZ;
+
+static void ipfrag_secret_rebuild(unsigned long dummy)
+{
+ unsigned long now = jiffies;
+ int i;
+
+ write_lock(&ipfrag_lock);
+ get_random_bytes(&ipfrag_hash_rnd, sizeof(u32));
+ for (i = 0; i < IPQ_HASHSZ; i++) {
+ struct ipq *q;
+
+ q = ipq_hash[i];
+ while (q) {
+ struct ipq *next = q->next;
+ unsigned int hval = ipqhashfn(q->id, q->saddr,
+ q->daddr, q->protocol);
+
+ if (hval != i) {
+ /* Unlink. */
+ if (q->next)
+ q->next->pprev = q->pprev;
+ *q->pprev = q->next;
+
+ /* Relink to new hash chain. */
+ if ((q->next = ipq_hash[hval]) != NULL)
+ q->next->pprev = &q->next;
+ ipq_hash[hval] = q;
+ q->pprev = &ipq_hash[hval];
+ }
+
+ q = next;
+ }
+ }
+ write_unlock(&ipfrag_lock);
+
+ mod_timer(&ipfrag_secret_timer, now + sysctl_ipfrag_secret_interval);
+}
+
+atomic_t ip_frag_mem = ATOMIC_INIT(0); /* Memory used for fragments */
+
+/* Memory Tracking Functions. */
+static __inline__ void frag_kfree_skb(struct sk_buff *skb, int *work)
+{
+ if (work)
+ *work -= skb->truesize;
+ atomic_sub(skb->truesize, &ip_frag_mem);
+ kfree_skb(skb);
+}
+
+static __inline__ void frag_free_queue(struct ipq *qp, int *work)
+{
+ if (work)
+ *work -= sizeof(struct ipq);
+ atomic_sub(sizeof(struct ipq), &ip_frag_mem);
+ kfree(qp);
+}
+
+static __inline__ struct ipq *frag_alloc_queue(void)
+{
+ struct ipq *qp = kmalloc(sizeof(struct ipq), GFP_ATOMIC);
+
+ if(!qp)
+ return NULL;
+ atomic_add(sizeof(struct ipq), &ip_frag_mem);
+ return qp;
+}
+
+
+/* Destruction primitives. */
+
+/* Complete destruction of ipq. */
+static void ip_frag_destroy(struct ipq *qp, int *work)
+{
+ struct sk_buff *fp;
+
+ BUG_TRAP(qp->last_in&COMPLETE);
+ BUG_TRAP(del_timer(&qp->timer) == 0);
+
+ /* Release all fragment data. */
+ fp = qp->fragments;
+ while (fp) {
+ struct sk_buff *xp = fp->next;
+
+ frag_kfree_skb(fp, work);
+ fp = xp;
+ }
+
+ /* Finally, release the queue descriptor itself. */
+ frag_free_queue(qp, work);
+}
+
+static __inline__ void ipq_put(struct ipq *ipq, int *work)
+{
+ if (atomic_dec_and_test(&ipq->refcnt))
+ ip_frag_destroy(ipq, work);
+}
+
+/* Kill ipq entry. It is not destroyed immediately,
+ * because caller (and someone more) holds reference count.
+ */
+static void ipq_kill(struct ipq *ipq)
+{
+ if (del_timer(&ipq->timer))
+ atomic_dec(&ipq->refcnt);
+
+ if (!(ipq->last_in & COMPLETE)) {
+ ipq_unlink(ipq);
+ atomic_dec(&ipq->refcnt);
+ ipq->last_in |= COMPLETE;
+ }
+}
+
+/* Memory limiting on fragments. Evictor trashes the oldest
+ * fragment queue until we are back under the threshold.
+ */
+static void ip_evictor(void)
+{
+ struct ipq *qp;
+ struct list_head *tmp;
+ int work;
+
+ work = atomic_read(&ip_frag_mem) - sysctl_ipfrag_low_thresh;
+ if (work <= 0)
+ return;
+
+ while (work > 0) {
+ read_lock(&ipfrag_lock);
+ if (list_empty(&ipq_lru_list)) {
+ read_unlock(&ipfrag_lock);
+ return;
+ }
+ tmp = ipq_lru_list.next;
+ qp = list_entry(tmp, struct ipq, lru_list);
+ atomic_inc(&qp->refcnt);
+ read_unlock(&ipfrag_lock);
+
+ spin_lock(&qp->lock);
+ if (!(qp->last_in&COMPLETE))
+ ipq_kill(qp);
+ spin_unlock(&qp->lock);
+
+ ipq_put(qp, &work);
+ IP_INC_STATS_BH(IPSTATS_MIB_REASMFAILS);
+ }
+}
+
+/*
+ * Oops, a fragment queue timed out. Kill it and send an ICMP reply.
+ */
+static void ip_expire(unsigned long arg)
+{
+ struct ipq *qp = (struct ipq *) arg;
+
+ spin_lock(&qp->lock);
+
+ if (qp->last_in & COMPLETE)
+ goto out;
+
+ ipq_kill(qp);
+
+ IP_INC_STATS_BH(IPSTATS_MIB_REASMTIMEOUT);
+ IP_INC_STATS_BH(IPSTATS_MIB_REASMFAILS);
+
+ if ((qp->last_in&FIRST_IN) && qp->fragments != NULL) {
+ struct sk_buff *head = qp->fragments;
+ /* Send an ICMP "Fragment Reassembly Timeout" message. */
+ if ((head->dev = dev_get_by_index(qp->iif)) != NULL) {
+ icmp_send(head, ICMP_TIME_EXCEEDED, ICMP_EXC_FRAGTIME, 0);
+ dev_put(head->dev);
+ }
+ }
+out:
+ spin_unlock(&qp->lock);
+ ipq_put(qp, NULL);
+}
+
+/* Creation primitives. */
+
+static struct ipq *ip_frag_intern(unsigned int hash, struct ipq *qp_in)
+{
+ struct ipq *qp;
+
+ write_lock(&ipfrag_lock);
+#ifdef CONFIG_SMP
+ /* With SMP race we have to recheck hash table, because
+ * such entry could be created on other cpu, while we
+ * promoted read lock to write lock.
+ */
+ for(qp = ipq_hash[hash]; qp; qp = qp->next) {
+ if(qp->id == qp_in->id &&
+ qp->saddr == qp_in->saddr &&
+ qp->daddr == qp_in->daddr &&
+ qp->protocol == qp_in->protocol &&
+ qp->user == qp_in->user) {
+ atomic_inc(&qp->refcnt);
+ write_unlock(&ipfrag_lock);
+ qp_in->last_in |= COMPLETE;
+ ipq_put(qp_in, NULL);
+ return qp;
+ }
+ }
+#endif
+ qp = qp_in;
+
+ if (!mod_timer(&qp->timer, jiffies + sysctl_ipfrag_time))
+ atomic_inc(&qp->refcnt);
+
+ atomic_inc(&qp->refcnt);
+ if((qp->next = ipq_hash[hash]) != NULL)
+ qp->next->pprev = &qp->next;
+ ipq_hash[hash] = qp;
+ qp->pprev = &ipq_hash[hash];
+ INIT_LIST_HEAD(&qp->lru_list);
+ list_add_tail(&qp->lru_list, &ipq_lru_list);
+ ip_frag_nqueues++;
+ write_unlock(&ipfrag_lock);
+ return qp;
+}
+
+/* Add an entry to the 'ipq' queue for a newly received IP datagram. */
+static struct ipq *ip_frag_create(unsigned hash, struct iphdr *iph, u32 user)
+{
+ struct ipq *qp;
+
+ if ((qp = frag_alloc_queue()) == NULL)
+ goto out_nomem;
+
+ qp->protocol = iph->protocol;
+ qp->last_in = 0;
+ qp->id = iph->id;
+ qp->saddr = iph->saddr;
+ qp->daddr = iph->daddr;
+ qp->user = user;
+ qp->len = 0;
+ qp->meat = 0;
+ qp->fragments = NULL;
+ qp->iif = 0;
+
+ /* Initialize a timer for this entry. */
+ init_timer(&qp->timer);
+ qp->timer.data = (unsigned long) qp; /* pointer to queue */
+ qp->timer.function = ip_expire; /* expire function */
+ spin_lock_init(&qp->lock);
+ atomic_set(&qp->refcnt, 1);
+
+ return ip_frag_intern(hash, qp);
+
+out_nomem:
+ NETDEBUG(if (net_ratelimit()) printk(KERN_ERR "ip_frag_create: no memory left !\n"));
+ return NULL;
+}
+
+/* Find the correct entry in the "incomplete datagrams" queue for
+ * this IP datagram, and create new one, if nothing is found.
+ */
+static inline struct ipq *ip_find(struct iphdr *iph, u32 user)
+{
+ __u16 id = iph->id;
+ __u32 saddr = iph->saddr;
+ __u32 daddr = iph->daddr;
+ __u8 protocol = iph->protocol;
+ unsigned int hash = ipqhashfn(id, saddr, daddr, protocol);
+ struct ipq *qp;
+
+ read_lock(&ipfrag_lock);
+ for(qp = ipq_hash[hash]; qp; qp = qp->next) {
+ if(qp->id == id &&
+ qp->saddr == saddr &&
+ qp->daddr == daddr &&
+ qp->protocol == protocol &&
+ qp->user == user) {
+ atomic_inc(&qp->refcnt);
+ read_unlock(&ipfrag_lock);
+ return qp;
+ }
+ }
+ read_unlock(&ipfrag_lock);
+
+ return ip_frag_create(hash, iph, user);
+}
+
+/* Add new segment to existing queue. */
+static void ip_frag_queue(struct ipq *qp, struct sk_buff *skb)
+{
+ struct sk_buff *prev, *next;
+ int flags, offset;
+ int ihl, end;
+
+ if (qp->last_in & COMPLETE)
+ goto err;
+
+ offset = ntohs(skb->nh.iph->frag_off);
+ flags = offset & ~IP_OFFSET;
+ offset &= IP_OFFSET;
+ offset <<= 3; /* offset is in 8-byte chunks */
+ ihl = skb->nh.iph->ihl * 4;
+
+ /* Determine the position of this fragment. */
+ end = offset + skb->len - ihl;
+
+ /* 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 corrrupted.
+ */
+ if (end < qp->len ||
+ ((qp->last_in & LAST_IN) && end != qp->len))
+ goto err;
+ qp->last_in |= LAST_IN;
+ qp->len = end;
+ } else {
+ if (end&7) {
+ end &= ~7;
+ if (skb->ip_summed != CHECKSUM_UNNECESSARY)
+ skb->ip_summed = CHECKSUM_NONE;
+ }
+ if (end > qp->len) {
+ /* Some bits beyond end -> corruption. */
+ if (qp->last_in & LAST_IN)
+ goto err;
+ qp->len = end;
+ }
+ }
+ if (end == offset)
+ goto err;
+
+ if (pskb_pull(skb, ihl) == NULL)
+ goto err;
+ if (pskb_trim(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 = NULL;
+ for(next = qp->fragments; next != NULL; next = next->next) {
+ if (FRAG_CB(next)->offset >= offset)
+ break; /* bingo! */
+ prev = next;
+ }
+
+ /* 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;
+ if (end <= offset)
+ goto err;
+ if (!pskb_pull(skb, i))
+ goto err;
+ if (skb->ip_summed != CHECKSUM_UNNECESSARY)
+ skb->ip_summed = CHECKSUM_NONE;
+ }
+ }
+
+ 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->meat -= i;
+ if (next->ip_summed != CHECKSUM_UNNECESSARY)
+ next->ip_summed = CHECKSUM_NONE;
+ break;
+ } else {
+ struct sk_buff *free_it = next;
+
+ /* Old fragmnet is completely overridden with
+ * new one drop it.
+ */
+ next = next->next;
+
+ if (prev)
+ prev->next = next;
+ else
+ qp->fragments = next;
+
+ qp->meat -= free_it->len;
+ frag_kfree_skb(free_it, NULL);
+ }
+ }
+
+ FRAG_CB(skb)->offset = offset;
+
+ /* Insert this fragment in the chain of fragments. */
+ skb->next = next;
+ if (prev)
+ prev->next = skb;
+ else
+ qp->fragments = skb;
+
+ if (skb->dev)
+ qp->iif = skb->dev->ifindex;
+ skb->dev = NULL;
+ qp->stamp = skb->stamp;
+ qp->meat += skb->len;
+ atomic_add(skb->truesize, &ip_frag_mem);
+ if (offset == 0)
+ qp->last_in |= FIRST_IN;
+
+ write_lock(&ipfrag_lock);
+ list_move_tail(&qp->lru_list, &ipq_lru_list);
+ write_unlock(&ipfrag_lock);
+
+ return;
+
+err:
+ kfree_skb(skb);
+}
+
+
+/* Build a new IP datagram from all its fragments. */
+
+static struct sk_buff *ip_frag_reasm(struct ipq *qp, struct net_device *dev)
+{
+ struct iphdr *iph;
+ struct sk_buff *fp, *head = qp->fragments;
+ int len;
+ int ihlen;
+
+ ipq_kill(qp);
+
+ BUG_TRAP(head != NULL);
+ BUG_TRAP(FRAG_CB(head)->offset == 0);
+
+ /* Allocate a new buffer for the datagram. */
+ ihlen = head->nh.iph->ihl*4;
+ len = ihlen + qp->len;
+
+ if(len > 65535)
+ goto out_oversize;
+
+ /* Head of list must not be cloned. */
+ if (skb_cloned(head) && pskb_expand_head(head, 0, 0, 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_shinfo(head)->frag_list) {
+ struct sk_buff *clone;
+ int i, plen = 0;
+
+ if ((clone = alloc_skb(0, GFP_ATOMIC)) == NULL)
+ goto out_nomem;
+ clone->next = head->next;
+ head->next = clone;
+ skb_shinfo(clone)->frag_list = skb_shinfo(head)->frag_list;
+ skb_shinfo(head)->frag_list = NULL;
+ 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, &ip_frag_mem);
+ }
+
+ skb_shinfo(head)->frag_list = head->next;
+ skb_push(head, head->data - head->nh.raw);
+ atomic_sub(head->truesize, &ip_frag_mem);
+
+ 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_HW)
+ head->csum = csum_add(head->csum, fp->csum);
+ head->truesize += fp->truesize;
+ atomic_sub(fp->truesize, &ip_frag_mem);
+ }
+
+ head->next = NULL;
+ head->dev = dev;
+ head->stamp = qp->stamp;
+
+ iph = head->nh.iph;
+ iph->frag_off = 0;
+ iph->tot_len = htons(len);
+ IP_INC_STATS_BH(IPSTATS_MIB_REASMOKS);
+ qp->fragments = NULL;
+ return head;
+
+out_nomem:
+ NETDEBUG(if (net_ratelimit())
+ printk(KERN_ERR
+ "IP: queue_glue: no memory for gluing queue %p\n",
+ qp));
+ goto out_fail;
+out_oversize:
+ if (net_ratelimit())
+ printk(KERN_INFO
+ "Oversized IP packet from %d.%d.%d.%d.\n",
+ NIPQUAD(qp->saddr));
+out_fail:
+ IP_INC_STATS_BH(IPSTATS_MIB_REASMFAILS);
+ return NULL;
+}
+
+/* Process an incoming IP datagram fragment. */
+struct sk_buff *ip_defrag(struct sk_buff *skb, u32 user)
+{
+ struct iphdr *iph = skb->nh.iph;
+ struct ipq *qp;
+ struct net_device *dev;
+
+ IP_INC_STATS_BH(IPSTATS_MIB_REASMREQDS);
+
+ /* Start by cleaning up the memory. */
+ if (atomic_read(&ip_frag_mem) > sysctl_ipfrag_high_thresh)
+ ip_evictor();
+
+ dev = skb->dev;
+
+ /* Lookup (or create) queue header */
+ if ((qp = ip_find(iph, user)) != NULL) {
+ struct sk_buff *ret = NULL;
+
+ spin_lock(&qp->lock);
+
+ ip_frag_queue(qp, skb);
+
+ if (qp->last_in == (FIRST_IN|LAST_IN) &&
+ qp->meat == qp->len)
+ ret = ip_frag_reasm(qp, dev);
+
+ spin_unlock(&qp->lock);
+ ipq_put(qp, NULL);
+ return ret;
+ }
+
+ IP_INC_STATS_BH(IPSTATS_MIB_REASMFAILS);
+ kfree_skb(skb);
+ return NULL;
+}
+
+void ipfrag_init(void)
+{
+ ipfrag_hash_rnd = (u32) ((num_physpages ^ (num_physpages>>7)) ^
+ (jiffies ^ (jiffies >> 6)));
+
+ init_timer(&ipfrag_secret_timer);
+ ipfrag_secret_timer.function = ipfrag_secret_rebuild;
+ ipfrag_secret_timer.expires = jiffies + sysctl_ipfrag_secret_interval;
+ add_timer(&ipfrag_secret_timer);
+}
+
+EXPORT_SYMBOL(ip_defrag);