Linux-2.6.12-rc2v2.6.12-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!

1 files changed, 691 insertions, 0 deletions

diff --git a/net/ipv4/ip_fragment.c b/net/ipv4/ip_fragment.c
new file mode 100644
index 000000000000..7f68e27eb4ea
--- /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);