patch-2.4.19 linux-2.4.19/net/ipv4/netfilter/arp_tables.c

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diff -urN linux-2.4.18/net/ipv4/netfilter/arp_tables.c linux-2.4.19/net/ipv4/netfilter/arp_tables.c
@@ -0,0 +1,1313 @@
+/*
+ * Packet matching code for ARP packets.
+ *
+ * Based heavily, if not almost entirely, upon ip_tables.c framework.
+ *
+ * Some ARP specific bits are:
+ *
+ * Copyright (C) 2002 David S. Miller (davem@redhat.com)
+ *
+ */
+
+#include <linux/config.h>
+#include <linux/kernel.h>
+#include <linux/skbuff.h>
+#include <linux/netdevice.h>
+#include <linux/if_arp.h>
+#include <linux/kmod.h>
+#include <linux/vmalloc.h>
+#include <linux/proc_fs.h>
+#include <linux/module.h>
+#include <linux/init.h>
+
+#include <asm/uaccess.h>
+#include <asm/semaphore.h>
+
+#include <linux/netfilter_arp/arp_tables.h>
+
+/*#define DEBUG_ARP_TABLES*/
+/*#define DEBUG_ARP_TABLES_USER*/
+
+#ifdef DEBUG_ARP_TABLES
+#define dprintf(format, args...)  printk(format , ## args)
+#else
+#define dprintf(format, args...)
+#endif
+
+#ifdef DEBUG_ARP_TABLES_USER
+#define duprintf(format, args...) printk(format , ## args)
+#else
+#define duprintf(format, args...)
+#endif
+
+#ifdef CONFIG_NETFILTER_DEBUG
+#define ARP_NF_ASSERT(x)					\
+do {								\
+	if (!(x))						\
+		printk("ARP_NF_ASSERT: %s:%s:%u\n",		\
+		       __FUNCTION__, __FILE__, __LINE__);	\
+} while(0)
+#else
+#define ARP_NF_ASSERT(x)
+#endif
+#define SMP_ALIGN(x) (((x) + SMP_CACHE_BYTES-1) & ~(SMP_CACHE_BYTES-1))
+
+static DECLARE_MUTEX(arpt_mutex);
+
+#define ASSERT_READ_LOCK(x) ARP_NF_ASSERT(down_trylock(&arpt_mutex) != 0)
+#define ASSERT_WRITE_LOCK(x) ARP_NF_ASSERT(down_trylock(&arpt_mutex) != 0)
+#include <linux/netfilter_ipv4/lockhelp.h>
+#include <linux/netfilter_ipv4/listhelp.h>
+
+struct arpt_table_info {
+	unsigned int size;
+	unsigned int number;
+	unsigned int initial_entries;
+	unsigned int hook_entry[NF_ARP_NUMHOOKS];
+	unsigned int underflow[NF_ARP_NUMHOOKS];
+	char entries[0] __attribute__((aligned(SMP_CACHE_BYTES)));
+};
+
+static LIST_HEAD(arpt_target);
+static LIST_HEAD(arpt_tables);
+#define ADD_COUNTER(c,b,p) do { (c).bcnt += (b); (c).pcnt += (p); } while(0)
+
+#ifdef CONFIG_SMP
+#define TABLE_OFFSET(t,p) (SMP_ALIGN((t)->size)*(p))
+#else
+#define TABLE_OFFSET(t,p) 0
+#endif
+
+static inline int arp_devaddr_compare(const struct arpt_devaddr_info *ap,
+				      char *hdr_addr, int len)
+{
+	int i, ret;
+
+	if (len > ARPT_DEV_ADDR_LEN_MAX)
+		len = ARPT_DEV_ADDR_LEN_MAX;
+
+	ret = 0;
+	for (i = 0; i < len; i++)
+		ret |= (hdr_addr[i] ^ ap->addr[i]) & ap->mask[i];
+
+	return (ret != 0);
+}
+
+/* Returns whether packet matches rule or not. */
+static inline int arp_packet_match(const struct arphdr *arphdr,
+				   struct net_device *dev,
+				   const char *indev,
+				   const char *outdev,
+				   const struct arpt_arp *arpinfo)
+{
+	char *arpptr = (char *)(arphdr + 1);
+	char *src_devaddr, *tgt_devaddr;
+	u32 *src_ipaddr, *tgt_ipaddr;
+	int i, ret;
+
+#define FWINV(bool,invflg) ((bool) ^ !!(arpinfo->invflags & invflg))
+
+	if (FWINV((arphdr->ar_op & arpinfo->arpop_mask) != arpinfo->arpop,
+		  ARPT_INV_ARPOP)) {
+		dprintf("ARP operation field mismatch.\n");
+		dprintf("ar_op: %04x info->arpop: %04x info->arpop_mask: %04x\n",
+			arphdr->ar_op, arpinfo->arpop, arpinfo->arpop_mask);
+		return 0;
+	}
+
+	if (FWINV((arphdr->ar_hrd & arpinfo->arhrd_mask) != arpinfo->arhrd,
+		  ARPT_INV_ARPHRD)) {
+		dprintf("ARP hardware address format mismatch.\n");
+		dprintf("ar_hrd: %04x info->arhrd: %04x info->arhrd_mask: %04x\n",
+			arphdr->ar_hrd, arpinfo->arhrd, arpinfo->arhrd_mask);
+		return 0;
+	}
+
+	if (FWINV((arphdr->ar_pro & arpinfo->arpro_mask) != arpinfo->arpro,
+		  ARPT_INV_ARPPRO)) {
+		dprintf("ARP protocol address format mismatch.\n");
+		dprintf("ar_pro: %04x info->arpro: %04x info->arpro_mask: %04x\n",
+			arphdr->ar_pro, arpinfo->arpro, arpinfo->arpro_mask);
+		return 0;
+	}
+
+	if (FWINV((arphdr->ar_hln & arpinfo->arhln_mask) != arpinfo->arhln,
+		  ARPT_INV_ARPHLN)) {
+		dprintf("ARP hardware address length mismatch.\n");
+		dprintf("ar_hln: %02x info->arhln: %02x info->arhln_mask: %02x\n",
+			arphdr->ar_hln, arpinfo->arhln, arpinfo->arhln_mask);
+	}
+
+	src_devaddr = arpptr;
+	arpptr += dev->addr_len;
+	src_ipaddr = (u32 *) arpptr;
+	arpptr += sizeof(u32);
+	tgt_devaddr = arpptr;
+	arpptr += dev->addr_len;
+	tgt_ipaddr = (u32 *) arpptr;
+
+	if (FWINV(arp_devaddr_compare(&arpinfo->src_devaddr, src_devaddr, dev->addr_len),
+		  ARPT_INV_SRCDEVADDR) ||
+	    FWINV(arp_devaddr_compare(&arpinfo->tgt_devaddr, tgt_devaddr, dev->addr_len),
+		  ARPT_INV_TGTDEVADDR)) {
+		dprintf("Source or target device address mismatch.\n");
+
+		return 0;
+	}
+
+	if (FWINV(((*src_ipaddr) & arpinfo->smsk.s_addr) != arpinfo->src.s_addr,
+		  ARPT_INV_SRCIP) ||
+	    FWINV((((*tgt_ipaddr) & arpinfo->tmsk.s_addr) != arpinfo->tgt.s_addr),
+		  ARPT_INV_TGTIP)) {
+		dprintf("Source or target IP address mismatch.\n");
+
+		dprintf("SRC: %u.%u.%u.%u. Mask: %u.%u.%u.%u. Target: %u.%u.%u.%u.%s\n",
+			NIPQUAD(*src_ipaddr),
+			NIPQUAD(arpinfo->smsk.s_addr),
+			NIPQUAD(arpinfo->src.s_addr),
+			arpinfo->invflags & ARPT_INV_SRCIP ? " (INV)" : "");
+		dprintf("TGT: %u.%u.%u.%u Mask: %u.%u.%u.%u Target: %u.%u.%u.%u.%s\n",
+			NIPQUAD(*tgt_ipaddr),
+			NIPQUAD(arpinfo->tmsk.s_addr),
+			NIPQUAD(arpinfo->tgt.s_addr),
+			arpinfo->invflags & ARPT_INV_TGTIP ? " (INV)" : "");
+		return 0;
+	}
+
+	/* Look for ifname matches; this should unroll nicely. */
+	for (i = 0, ret = 0; i < IFNAMSIZ/sizeof(unsigned long); i++) {
+		ret |= (((const unsigned long *)indev)[i]
+			^ ((const unsigned long *)arpinfo->iniface)[i])
+			& ((const unsigned long *)arpinfo->iniface_mask)[i];
+	}
+
+	if (FWINV(ret != 0, ARPT_INV_VIA_IN)) {
+		dprintf("VIA in mismatch (%s vs %s).%s\n",
+			indev, arpinfo->iniface,
+			arpinfo->invflags&ARPT_INV_VIA_IN ?" (INV)":"");
+		return 0;
+	}
+
+	for (i = 0, ret = 0; i < IFNAMSIZ/sizeof(unsigned long); i++) {
+		ret |= (((const unsigned long *)outdev)[i]
+			^ ((const unsigned long *)arpinfo->outiface)[i])
+			& ((const unsigned long *)arpinfo->outiface_mask)[i];
+	}
+
+	if (FWINV(ret != 0, ARPT_INV_VIA_OUT)) {
+		dprintf("VIA out mismatch (%s vs %s).%s\n",
+			outdev, arpinfo->outiface,
+			arpinfo->invflags&ARPT_INV_VIA_OUT ?" (INV)":"");
+		return 0;
+	}
+
+	return 1;
+}
+
+static inline int arp_checkentry(const struct arpt_arp *arp)
+{
+	if (arp->flags & ~ARPT_F_MASK) {
+		duprintf("Unknown flag bits set: %08X\n",
+			 arp->flags & ~ARPT_F_MASK);
+		return 0;
+	}
+	if (arp->invflags & ~ARPT_INV_MASK) {
+		duprintf("Unknown invflag bits set: %08X\n",
+			 arp->invflags & ~ARPT_INV_MASK);
+		return 0;
+	}
+
+	return 1;
+}
+
+static unsigned int arpt_error(struct sk_buff **pskb,
+			       unsigned int hooknum,
+			       const struct net_device *in,
+			       const struct net_device *out,
+			       const void *targinfo,
+			       void *userinfo)
+{
+	if (net_ratelimit())
+		printk("arp_tables: error: '%s'\n", (char *)targinfo);
+
+	return NF_DROP;
+}
+
+static inline struct arpt_entry *get_entry(void *base, unsigned int offset)
+{
+	return (struct arpt_entry *)(base + offset);
+}
+
+unsigned int arpt_do_table(struct sk_buff **pskb,
+			   unsigned int hook,
+			   const struct net_device *in,
+			   const struct net_device *out,
+			   struct arpt_table *table,
+			   void *userdata)
+{
+	static const char nulldevname[IFNAMSIZ] = { 0 };
+	unsigned int verdict = NF_DROP;
+	struct arphdr *arp = (*pskb)->nh.arph;
+	int hotdrop = 0;
+	struct arpt_entry *e, *back;
+	const char *indev, *outdev;
+	void *table_base;
+
+	indev = in ? in->name : nulldevname;
+	outdev = out ? out->name : nulldevname;
+
+	read_lock_bh(&table->lock);
+	table_base = (void *)table->private->entries
+		+ TABLE_OFFSET(table->private,
+			       cpu_number_map(smp_processor_id()));
+	e = get_entry(table_base, table->private->hook_entry[hook]);
+	back = get_entry(table_base, table->private->underflow[hook]);
+
+	do {
+		if (arp_packet_match(arp, (*pskb)->dev, indev, outdev, &e->arp)) {
+			struct arpt_entry_target *t;
+			int hdr_len;
+
+			hdr_len = sizeof(*arp) + (2 * sizeof(struct in_addr)) +
+				(2 * (*pskb)->dev->addr_len);
+			ADD_COUNTER(e->counters, hdr_len, 1);
+
+			t = arpt_get_target(e);
+
+			/* Standard target? */
+			if (!t->u.kernel.target->target) {
+				int v;
+
+				v = ((struct arpt_standard_target *)t)->verdict;
+				if (v < 0) {
+					/* Pop from stack? */
+					if (v != ARPT_RETURN) {
+						verdict = (unsigned)(-v) - 1;
+						break;
+					}
+					e = back;
+					back = get_entry(table_base,
+							 back->comefrom);
+					continue;
+				}
+				if (table_base + v
+				    != (void *)e + e->next_offset) {
+					/* Save old back ptr in next entry */
+					struct arpt_entry *next
+						= (void *)e + e->next_offset;
+					next->comefrom =
+						(void *)back - table_base;
+
+					/* set back pointer to next entry */
+					back = next;
+				}
+
+				e = get_entry(table_base, v);
+			} else {
+				/* Targets which reenter must return
+				 * abs. verdicts
+				 */
+				verdict = t->u.kernel.target->target(pskb,
+								     hook,
+								     in, out,
+								     t->data,
+								     userdata);
+
+				/* Target might have changed stuff. */
+				arp = (*pskb)->nh.arph;
+
+				if (verdict == ARPT_CONTINUE)
+					e = (void *)e + e->next_offset;
+				else
+					/* Verdict */
+					break;
+			}
+		} else {
+			e = (void *)e + e->next_offset;
+		}
+	} while (!hotdrop);
+	read_unlock_bh(&table->lock);
+
+	if (hotdrop)
+		return NF_DROP;
+	else
+		return verdict;
+}
+
+static inline void *find_inlist_lock_noload(struct list_head *head,
+					    const char *name,
+					    int *error,
+					    struct semaphore *mutex)
+{
+	void *ret;
+
+	*error = down_interruptible(mutex);
+	if (*error != 0)
+		return NULL;
+
+	ret = list_named_find(head, name);
+	if (!ret) {
+		*error = -ENOENT;
+		up(mutex);
+	}
+	return ret;
+}
+
+#ifndef CONFIG_KMOD
+#define find_inlist_lock(h,n,p,e,m) find_inlist_lock_noload((h),(n),(e),(m))
+#else
+static void *
+find_inlist_lock(struct list_head *head,
+		 const char *name,
+		 const char *prefix,
+		 int *error,
+		 struct semaphore *mutex)
+{
+	void *ret;
+
+	ret = find_inlist_lock_noload(head, name, error, mutex);
+	if (!ret) {
+		char modulename[ARPT_FUNCTION_MAXNAMELEN + strlen(prefix) + 1];
+		strcpy(modulename, prefix);
+		strcat(modulename, name);
+		duprintf("find_inlist: loading `%s'.\n", modulename);
+		request_module(modulename);
+		ret = find_inlist_lock_noload(head, name, error, mutex);
+	}
+
+	return ret;
+}
+#endif
+
+static inline struct arpt_table *find_table_lock(const char *name, int *error, struct semaphore *mutex)
+{
+	return find_inlist_lock(&arpt_tables, name, "arptable_", error, mutex);
+}
+
+static inline struct arpt_target *find_target_lock(const char *name, int *error, struct semaphore *mutex)
+{
+	return find_inlist_lock(&arpt_target, name, "arpt_", error, mutex);
+}
+
+/* All zeroes == unconditional rule. */
+static inline int unconditional(const struct arpt_arp *arp)
+{
+	unsigned int i;
+
+	for (i = 0; i < sizeof(*arp)/sizeof(__u32); i++)
+		if (((__u32 *)arp)[i])
+			return 0;
+
+	return 1;
+}
+
+/* Figures out from what hook each rule can be called: returns 0 if
+ * there are loops.  Puts hook bitmask in comefrom.
+ */
+static int mark_source_chains(struct arpt_table_info *newinfo, unsigned int valid_hooks)
+{
+	unsigned int hook;
+
+	/* No recursion; use packet counter to save back ptrs (reset
+	 * to 0 as we leave), and comefrom to save source hook bitmask.
+	 */
+	for (hook = 0; hook < NF_ARP_NUMHOOKS; hook++) {
+		unsigned int pos = newinfo->hook_entry[hook];
+		struct arpt_entry *e
+			= (struct arpt_entry *)(newinfo->entries + pos);
+
+		if (!(valid_hooks & (1 << hook)))
+			continue;
+
+		/* Set initial back pointer. */
+		e->counters.pcnt = pos;
+
+		for (;;) {
+			struct arpt_standard_target *t
+				= (void *)arpt_get_target(e);
+
+			if (e->comefrom & (1 << NF_ARP_NUMHOOKS)) {
+				printk("arptables: loop hook %u pos %u %08X.\n",
+				       hook, pos, e->comefrom);
+				return 0;
+			}
+			e->comefrom
+				|= ((1 << hook) | (1 << NF_ARP_NUMHOOKS));
+
+			/* Unconditional return/END. */
+			if (e->target_offset == sizeof(struct arpt_entry)
+			    && (strcmp(t->target.u.user.name,
+				       ARPT_STANDARD_TARGET) == 0)
+			    && t->verdict < 0
+			    && unconditional(&e->arp)) {
+				unsigned int oldpos, size;
+
+				/* Return: backtrack through the last
+				 * big jump.
+				 */
+				do {
+					e->comefrom ^= (1<<NF_ARP_NUMHOOKS);
+					oldpos = pos;
+					pos = e->counters.pcnt;
+					e->counters.pcnt = 0;
+
+					/* We're at the start. */
+					if (pos == oldpos)
+						goto next;
+
+					e = (struct arpt_entry *)
+						(newinfo->entries + pos);
+				} while (oldpos == pos + e->next_offset);
+
+				/* Move along one */
+				size = e->next_offset;
+				e = (struct arpt_entry *)
+					(newinfo->entries + pos + size);
+				e->counters.pcnt = pos;
+				pos += size;
+			} else {
+				int newpos = t->verdict;
+
+				if (strcmp(t->target.u.user.name,
+					   ARPT_STANDARD_TARGET) == 0
+				    && newpos >= 0) {
+					/* This a jump; chase it. */
+					duprintf("Jump rule %u -> %u\n",
+						 pos, newpos);
+				} else {
+					/* ... this is a fallthru */
+					newpos = pos + e->next_offset;
+				}
+				e = (struct arpt_entry *)
+					(newinfo->entries + newpos);
+				e->counters.pcnt = pos;
+				pos = newpos;
+			}
+		}
+		next:
+		duprintf("Finished chain %u\n", hook);
+	}
+	return 1;
+}
+
+static inline int standard_check(const struct arpt_entry_target *t,
+				 unsigned int max_offset)
+{
+	struct arpt_standard_target *targ = (void *)t;
+
+	/* Check standard info. */
+	if (t->u.target_size
+	    != ARPT_ALIGN(sizeof(struct arpt_standard_target))) {
+		duprintf("arpt_standard_check: target size %u != %Zu\n",
+			 t->u.target_size,
+			 ARPT_ALIGN(sizeof(struct arpt_standard_target)));
+		return 0;
+	}
+
+	if (targ->verdict >= 0
+	    && targ->verdict > max_offset - sizeof(struct arpt_entry)) {
+		duprintf("arpt_standard_check: bad verdict (%i)\n",
+			 targ->verdict);
+		return 0;
+	}
+
+	if (targ->verdict < -NF_MAX_VERDICT - 1) {
+		duprintf("arpt_standard_check: bad negative verdict (%i)\n",
+			 targ->verdict);
+		return 0;
+	}
+	return 1;
+}
+
+static struct arpt_target arpt_standard_target;
+
+static inline int check_entry(struct arpt_entry *e, const char *name, unsigned int size,
+			      unsigned int *i)
+{
+	struct arpt_entry_target *t;
+	struct arpt_target *target;
+	int ret;
+
+	if (!arp_checkentry(&e->arp)) {
+		duprintf("arp_tables: arp check failed %p %s.\n", e, name);
+		return -EINVAL;
+	}
+
+	t = arpt_get_target(e);
+	target = find_target_lock(t->u.user.name, &ret, &arpt_mutex);
+	if (!target) {
+		duprintf("check_entry: `%s' not found\n", t->u.user.name);
+		goto out;
+	}
+	if (target->me)
+		__MOD_INC_USE_COUNT(target->me);
+	t->u.kernel.target = target;
+	up(&arpt_mutex);
+
+	if (t->u.kernel.target == &arpt_standard_target) {
+		if (!standard_check(t, size)) {
+			ret = -EINVAL;
+			goto out;
+		}
+	} else if (t->u.kernel.target->checkentry
+		   && !t->u.kernel.target->checkentry(name, e, t->data,
+						      t->u.target_size
+						      - sizeof(*t),
+						      e->comefrom)) {
+		if (t->u.kernel.target->me)
+			__MOD_DEC_USE_COUNT(t->u.kernel.target->me);
+		duprintf("arp_tables: check failed for `%s'.\n",
+			 t->u.kernel.target->name);
+		ret = -EINVAL;
+		goto out;
+	}
+
+	(*i)++;
+	return 0;
+
+out:
+	return ret;
+}
+
+static inline int check_entry_size_and_hooks(struct arpt_entry *e,
+					     struct arpt_table_info *newinfo,
+					     unsigned char *base,
+					     unsigned char *limit,
+					     const unsigned int *hook_entries,
+					     const unsigned int *underflows,
+					     unsigned int *i)
+{
+	unsigned int h;
+
+	if ((unsigned long)e % __alignof__(struct arpt_entry) != 0
+	    || (unsigned char *)e + sizeof(struct arpt_entry) >= limit) {
+		duprintf("Bad offset %p\n", e);
+		return -EINVAL;
+	}
+
+	if (e->next_offset
+	    < sizeof(struct arpt_entry) + sizeof(struct arpt_entry_target)) {
+		duprintf("checking: element %p size %u\n",
+			 e, e->next_offset);
+		return -EINVAL;
+	}
+
+	/* Check hooks & underflows */
+	for (h = 0; h < NF_ARP_NUMHOOKS; h++) {
+		if ((unsigned char *)e - base == hook_entries[h])
+			newinfo->hook_entry[h] = hook_entries[h];
+		if ((unsigned char *)e - base == underflows[h])
+			newinfo->underflow[h] = underflows[h];
+	}
+
+	/* FIXME: underflows must be unconditional, standard verdicts
+           < 0 (not ARPT_RETURN). --RR */
+
+	/* Clear counters and comefrom */
+	e->counters = ((struct arpt_counters) { 0, 0 });
+	e->comefrom = 0;
+
+	(*i)++;
+	return 0;
+}
+
+static inline int cleanup_entry(struct arpt_entry *e, unsigned int *i)
+{
+	struct arpt_entry_target *t;
+
+	if (i && (*i)-- == 0)
+		return 1;
+
+	t = arpt_get_target(e);
+	if (t->u.kernel.target->destroy)
+		t->u.kernel.target->destroy(t->data,
+					    t->u.target_size - sizeof(*t));
+	if (t->u.kernel.target->me)
+		__MOD_DEC_USE_COUNT(t->u.kernel.target->me);
+
+	return 0;
+}
+
+/* Checks and translates the user-supplied table segment (held in
+ * newinfo).
+ */
+static int translate_table(const char *name,
+			   unsigned int valid_hooks,
+			   struct arpt_table_info *newinfo,
+			   unsigned int size,
+			   unsigned int number,
+			   const unsigned int *hook_entries,
+			   const unsigned int *underflows)
+{
+	unsigned int i;
+	int ret;
+
+	newinfo->size = size;
+	newinfo->number = number;
+
+	/* Init all hooks to impossible value. */
+	for (i = 0; i < NF_ARP_NUMHOOKS; i++) {
+		newinfo->hook_entry[i] = 0xFFFFFFFF;
+		newinfo->underflow[i] = 0xFFFFFFFF;
+	}
+
+	duprintf("translate_table: size %u\n", newinfo->size);
+	i = 0;
+
+	/* Walk through entries, checking offsets. */
+	ret = ARPT_ENTRY_ITERATE(newinfo->entries, newinfo->size,
+				 check_entry_size_and_hooks,
+				 newinfo,
+				 newinfo->entries,
+				 newinfo->entries + size,
+				 hook_entries, underflows, &i);
+	duprintf("translate_table: ARPT_ENTRY_ITERATE gives %d\n", ret);
+	if (ret != 0)
+		return ret;
+
+	if (i != number) {
+		duprintf("translate_table: %u not %u entries\n",
+			 i, number);
+		return -EINVAL;
+	}
+
+	/* Check hooks all assigned */
+	for (i = 0; i < NF_ARP_NUMHOOKS; i++) {
+		/* Only hooks which are valid */
+		if (!(valid_hooks & (1 << i)))
+			continue;
+		if (newinfo->hook_entry[i] == 0xFFFFFFFF) {
+			duprintf("Invalid hook entry %u %u\n",
+				 i, hook_entries[i]);
+			return -EINVAL;
+		}
+		if (newinfo->underflow[i] == 0xFFFFFFFF) {
+			duprintf("Invalid underflow %u %u\n",
+				 i, underflows[i]);
+			return -EINVAL;
+		}
+	}
+
+	if (!mark_source_chains(newinfo, valid_hooks)) {
+		duprintf("Looping hook\n");
+		return -ELOOP;
+	}
+
+	/* Finally, each sanity check must pass */
+	i = 0;
+	ret = ARPT_ENTRY_ITERATE(newinfo->entries, newinfo->size,
+				 check_entry, name, size, &i);
+
+	if (ret != 0) {
+		ARPT_ENTRY_ITERATE(newinfo->entries, newinfo->size,
+				   cleanup_entry, &i);
+		return ret;
+	}
+
+	/* And one copy for every other CPU */
+	for (i = 1; i < smp_num_cpus; i++) {
+		memcpy(newinfo->entries + SMP_ALIGN(newinfo->size)*i,
+		       newinfo->entries,
+		       SMP_ALIGN(newinfo->size));
+	}
+
+	return ret;
+}
+
+static struct arpt_table_info *replace_table(struct arpt_table *table,
+					     unsigned int num_counters,
+					     struct arpt_table_info *newinfo,
+					     int *error)
+{
+	struct arpt_table_info *oldinfo;
+
+	/* Do the substitution. */
+	write_lock_bh(&table->lock);
+	/* Check inside lock: is the old number correct? */
+	if (num_counters != table->private->number) {
+		duprintf("num_counters != table->private->number (%u/%u)\n",
+			 num_counters, table->private->number);
+		write_unlock_bh(&table->lock);
+		*error = -EAGAIN;
+		return NULL;
+	}
+	oldinfo = table->private;
+	table->private = newinfo;
+	newinfo->initial_entries = oldinfo->initial_entries;
+	write_unlock_bh(&table->lock);
+
+	return oldinfo;
+}
+
+/* Gets counters. */
+static inline int add_entry_to_counter(const struct arpt_entry *e,
+				       struct arpt_counters total[],
+				       unsigned int *i)
+{
+	ADD_COUNTER(total[*i], e->counters.bcnt, e->counters.pcnt);
+
+	(*i)++;
+	return 0;
+}
+
+static void get_counters(const struct arpt_table_info *t,
+			 struct arpt_counters counters[])
+{
+	unsigned int cpu;
+	unsigned int i;
+
+	for (cpu = 0; cpu < smp_num_cpus; cpu++) {
+		i = 0;
+		ARPT_ENTRY_ITERATE(t->entries + TABLE_OFFSET(t, cpu),
+				   t->size,
+				   add_entry_to_counter,
+				   counters,
+				   &i);
+	}
+}
+
+static int copy_entries_to_user(unsigned int total_size,
+				struct arpt_table *table,
+				void *userptr)
+{
+	unsigned int off, num, countersize;
+	struct arpt_entry *e;
+	struct arpt_counters *counters;
+	int ret = 0;
+
+	/* We need atomic snapshot of counters: rest doesn't change
+	 * (other than comefrom, which userspace doesn't care
+	 * about).
+	 */
+	countersize = sizeof(struct arpt_counters) * table->private->number;
+	counters = vmalloc(countersize);
+
+	if (counters == NULL)
+		return -ENOMEM;
+
+	/* First, sum counters... */
+	memset(counters, 0, countersize);
+	write_lock_bh(&table->lock);
+	get_counters(table->private, counters);
+	write_unlock_bh(&table->lock);
+
+	/* ... then copy entire thing from CPU 0... */
+	if (copy_to_user(userptr, table->private->entries, total_size) != 0) {
+		ret = -EFAULT;
+		goto free_counters;
+	}
+
+	/* FIXME: use iterator macros --RR */
+	/* ... then go back and fix counters and names */
+	for (off = 0, num = 0; off < total_size; off += e->next_offset, num++){
+		struct arpt_entry_target *t;
+
+		e = (struct arpt_entry *)(table->private->entries + off);
+		if (copy_to_user(userptr + off
+				 + offsetof(struct arpt_entry, counters),
+				 &counters[num],
+				 sizeof(counters[num])) != 0) {
+			ret = -EFAULT;
+			goto free_counters;
+		}
+
+		t = arpt_get_target(e);
+		if (copy_to_user(userptr + off + e->target_offset
+				 + offsetof(struct arpt_entry_target,
+					    u.user.name),
+				 t->u.kernel.target->name,
+				 strlen(t->u.kernel.target->name)+1) != 0) {
+			ret = -EFAULT;
+			goto free_counters;
+		}
+	}
+
+ free_counters:
+	vfree(counters);
+	return ret;
+}
+
+static int get_entries(const struct arpt_get_entries *entries,
+		       struct arpt_get_entries *uptr)
+{
+	int ret;
+	struct arpt_table *t;
+
+	t = find_table_lock(entries->name, &ret, &arpt_mutex);
+	if (t) {
+		duprintf("t->private->number = %u\n",
+			 t->private->number);
+		if (entries->size == t->private->size)
+			ret = copy_entries_to_user(t->private->size,
+						   t, uptr->entrytable);
+		else {
+			duprintf("get_entries: I've got %u not %u!\n",
+				 t->private->size,
+				 entries->size);
+			ret = -EINVAL;
+		}
+		up(&arpt_mutex);
+	} else
+		duprintf("get_entries: Can't find %s!\n",
+			 entries->name);
+
+	return ret;
+}
+
+static int do_replace(void *user, unsigned int len)
+{
+	int ret;
+	struct arpt_replace tmp;
+	struct arpt_table *t;
+	struct arpt_table_info *newinfo, *oldinfo;
+	struct arpt_counters *counters;
+
+	if (copy_from_user(&tmp, user, sizeof(tmp)) != 0)
+		return -EFAULT;
+
+	/* Hack: Causes ipchains to give correct error msg --RR */
+	if (len != sizeof(tmp) + tmp.size)
+		return -ENOPROTOOPT;
+
+	/* Pedantry: prevent them from hitting BUG() in vmalloc.c --RR */
+	if ((SMP_ALIGN(tmp.size) >> PAGE_SHIFT) + 2 > num_physpages)
+		return -ENOMEM;
+
+	newinfo = vmalloc(sizeof(struct arpt_table_info)
+			  + SMP_ALIGN(tmp.size) * smp_num_cpus);
+	if (!newinfo)
+		return -ENOMEM;
+
+	if (copy_from_user(newinfo->entries, user + sizeof(tmp),
+			   tmp.size) != 0) {
+		ret = -EFAULT;
+		goto free_newinfo;
+	}
+
+	counters = vmalloc(tmp.num_counters * sizeof(struct arpt_counters));
+	if (!counters) {
+		ret = -ENOMEM;
+		goto free_newinfo;
+	}
+	memset(counters, 0, tmp.num_counters * sizeof(struct arpt_counters));
+
+	ret = translate_table(tmp.name, tmp.valid_hooks,
+			      newinfo, tmp.size, tmp.num_entries,
+			      tmp.hook_entry, tmp.underflow);
+	if (ret != 0)
+		goto free_newinfo_counters;
+
+	duprintf("arp_tables: Translated table\n");
+
+	t = find_table_lock(tmp.name, &ret, &arpt_mutex);
+	if (!t)
+		goto free_newinfo_counters_untrans;
+
+	/* You lied! */
+	if (tmp.valid_hooks != t->valid_hooks) {
+		duprintf("Valid hook crap: %08X vs %08X\n",
+			 tmp.valid_hooks, t->valid_hooks);
+		ret = -EINVAL;
+		goto free_newinfo_counters_untrans_unlock;
+	}
+
+	oldinfo = replace_table(t, tmp.num_counters, newinfo, &ret);
+	if (!oldinfo)
+		goto free_newinfo_counters_untrans_unlock;
+
+	/* Update module usage count based on number of rules */
+	duprintf("do_replace: oldnum=%u, initnum=%u, newnum=%u\n",
+		oldinfo->number, oldinfo->initial_entries, newinfo->number);
+	if (t->me && (oldinfo->number <= oldinfo->initial_entries) &&
+ 	    (newinfo->number > oldinfo->initial_entries))
+		__MOD_INC_USE_COUNT(t->me);
+	else if (t->me && (oldinfo->number > oldinfo->initial_entries) &&
+	 	 (newinfo->number <= oldinfo->initial_entries))
+		__MOD_DEC_USE_COUNT(t->me);
+
+	/* Get the old counters. */
+	get_counters(oldinfo, counters);
+	/* Decrease module usage counts and free resource */
+	ARPT_ENTRY_ITERATE(oldinfo->entries, oldinfo->size, cleanup_entry,NULL);
+	vfree(oldinfo);
+	/* Silent error: too late now. */
+	copy_to_user(tmp.counters, counters,
+		     sizeof(struct arpt_counters) * tmp.num_counters);
+	vfree(counters);
+	up(&arpt_mutex);
+	return 0;
+
+ free_newinfo_counters_untrans_unlock:
+	up(&arpt_mutex);
+ free_newinfo_counters_untrans:
+	ARPT_ENTRY_ITERATE(newinfo->entries, newinfo->size, cleanup_entry, NULL);
+ free_newinfo_counters:
+	vfree(counters);
+ free_newinfo:
+	vfree(newinfo);
+	return ret;
+}
+
+/* We're lazy, and add to the first CPU; overflow works its fey magic
+ * and everything is OK.
+ */
+static inline int add_counter_to_entry(struct arpt_entry *e,
+				       const struct arpt_counters addme[],
+				       unsigned int *i)
+{
+
+	ADD_COUNTER(e->counters, addme[*i].bcnt, addme[*i].pcnt);
+
+	(*i)++;
+	return 0;
+}
+
+static int do_add_counters(void *user, unsigned int len)
+{
+	unsigned int i;
+	struct arpt_counters_info tmp, *paddc;
+	struct arpt_table *t;
+	int ret;
+
+	if (copy_from_user(&tmp, user, sizeof(tmp)) != 0)
+		return -EFAULT;
+
+	if (len != sizeof(tmp) + tmp.num_counters*sizeof(struct arpt_counters))
+		return -EINVAL;
+
+	paddc = vmalloc(len);
+	if (!paddc)
+		return -ENOMEM;
+
+	if (copy_from_user(paddc, user, len) != 0) {
+		ret = -EFAULT;
+		goto free;
+	}
+
+	t = find_table_lock(tmp.name, &ret, &arpt_mutex);
+	if (!t)
+		goto free;
+
+	write_lock_bh(&t->lock);
+	if (t->private->number != paddc->num_counters) {
+		ret = -EINVAL;
+		goto unlock_up_free;
+	}
+
+	i = 0;
+	ARPT_ENTRY_ITERATE(t->private->entries,
+			   t->private->size,
+			   add_counter_to_entry,
+			   paddc->counters,
+			   &i);
+ unlock_up_free:
+	write_unlock_bh(&t->lock);
+	up(&arpt_mutex);
+ free:
+	vfree(paddc);
+
+	return ret;
+}
+
+static int do_arpt_set_ctl(struct sock *sk, int cmd, void *user, unsigned int len)
+{
+	int ret;
+
+	if (!capable(CAP_NET_ADMIN))
+		return -EPERM;
+
+	switch (cmd) {
+	case ARPT_SO_SET_REPLACE:
+		ret = do_replace(user, len);
+		break;
+
+	case ARPT_SO_SET_ADD_COUNTERS:
+		ret = do_add_counters(user, len);
+		break;
+
+	default:
+		duprintf("do_arpt_set_ctl:  unknown request %i\n", cmd);
+		ret = -EINVAL;
+	}
+
+	return ret;
+}
+
+static int do_arpt_get_ctl(struct sock *sk, int cmd, void *user, int *len)
+{
+	int ret;
+
+	if (!capable(CAP_NET_ADMIN))
+		return -EPERM;
+
+	switch (cmd) {
+	case ARPT_SO_GET_INFO: {
+		char name[ARPT_TABLE_MAXNAMELEN];
+		struct arpt_table *t;
+
+		if (*len != sizeof(struct arpt_getinfo)) {
+			duprintf("length %u != %Zu\n", *len,
+				 sizeof(struct arpt_getinfo));
+			ret = -EINVAL;
+			break;
+		}
+
+		if (copy_from_user(name, user, sizeof(name)) != 0) {
+			ret = -EFAULT;
+			break;
+		}
+		name[ARPT_TABLE_MAXNAMELEN-1] = '\0';
+		t = find_table_lock(name, &ret, &arpt_mutex);
+		if (t) {
+			struct arpt_getinfo info;
+
+			info.valid_hooks = t->valid_hooks;
+			memcpy(info.hook_entry, t->private->hook_entry,
+			       sizeof(info.hook_entry));
+			memcpy(info.underflow, t->private->underflow,
+			       sizeof(info.underflow));
+			info.num_entries = t->private->number;
+			info.size = t->private->size;
+			strcpy(info.name, name);
+
+			if (copy_to_user(user, &info, *len) != 0)
+				ret = -EFAULT;
+			else
+				ret = 0;
+
+			up(&arpt_mutex);
+		}
+	}
+	break;
+
+	case ARPT_SO_GET_ENTRIES: {
+		struct arpt_get_entries get;
+
+		if (*len < sizeof(get)) {
+			duprintf("get_entries: %u < %Zu\n", *len, sizeof(get));
+			ret = -EINVAL;
+		} else if (copy_from_user(&get, user, sizeof(get)) != 0) {
+			ret = -EFAULT;
+		} else if (*len != sizeof(struct arpt_get_entries) + get.size) {
+			duprintf("get_entries: %u != %Zu\n", *len,
+				 sizeof(struct arpt_get_entries) + get.size);
+			ret = -EINVAL;
+		} else
+			ret = get_entries(&get, user);
+		break;
+	}
+
+	default:
+		duprintf("do_arpt_get_ctl: unknown request %i\n", cmd);
+		ret = -EINVAL;
+	}
+
+	return ret;
+}
+
+/* Registration hooks for targets. */
+int arpt_register_target(struct arpt_target *target)
+{
+	int ret;
+
+	MOD_INC_USE_COUNT;
+	ret = down_interruptible(&arpt_mutex);
+	if (ret != 0) {
+		MOD_DEC_USE_COUNT;
+		return ret;
+	}
+	if (!list_named_insert(&arpt_target, target)) {
+		duprintf("arpt_register_target: `%s' already in list!\n",
+			 target->name);
+		ret = -EINVAL;
+		MOD_DEC_USE_COUNT;
+	}
+	up(&arpt_mutex);
+	return ret;
+}
+
+void arpt_unregister_target(struct arpt_target *target)
+{
+	down(&arpt_mutex);
+	LIST_DELETE(&arpt_target, target);
+	up(&arpt_mutex);
+	MOD_DEC_USE_COUNT;
+}
+
+int arpt_register_table(struct arpt_table *table)
+{
+	int ret;
+	struct arpt_table_info *newinfo;
+	static struct arpt_table_info bootstrap
+		= { 0, 0, 0, { 0 }, { 0 }, { } };
+
+	MOD_INC_USE_COUNT;
+	newinfo = vmalloc(sizeof(struct arpt_table_info)
+			  + SMP_ALIGN(table->table->size) * smp_num_cpus);
+	if (!newinfo) {
+		ret = -ENOMEM;
+		MOD_DEC_USE_COUNT;
+		return ret;
+	}
+	memcpy(newinfo->entries, table->table->entries, table->table->size);
+
+	ret = translate_table(table->name, table->valid_hooks,
+			      newinfo, table->table->size,
+			      table->table->num_entries,
+			      table->table->hook_entry,
+			      table->table->underflow);
+	duprintf("arpt_register_table: translate table gives %d\n", ret);
+	if (ret != 0) {
+		vfree(newinfo);
+		MOD_DEC_USE_COUNT;
+		return ret;
+	}
+
+	ret = down_interruptible(&arpt_mutex);
+	if (ret != 0) {
+		vfree(newinfo);
+		MOD_DEC_USE_COUNT;
+		return ret;
+	}
+
+	/* Don't autoload: we'd eat our tail... */
+	if (list_named_find(&arpt_tables, table->name)) {
+		ret = -EEXIST;
+		goto free_unlock;
+	}
+
+	/* Simplifies replace_table code. */
+	table->private = &bootstrap;
+	if (!replace_table(table, 0, newinfo, &ret))
+		goto free_unlock;
+
+	duprintf("table->private->number = %u\n",
+		 table->private->number);
+	
+	/* save number of initial entries */
+	table->private->initial_entries = table->private->number;
+
+	table->lock = RW_LOCK_UNLOCKED;
+	list_prepend(&arpt_tables, table);
+
+ unlock:
+	up(&arpt_mutex);
+	return ret;
+
+ free_unlock:
+	vfree(newinfo);
+	MOD_DEC_USE_COUNT;
+	goto unlock;
+}
+
+void arpt_unregister_table(struct arpt_table *table)
+{
+	down(&arpt_mutex);
+	LIST_DELETE(&arpt_tables, table);
+	up(&arpt_mutex);
+
+	/* Decrease module usage counts and free resources */
+	ARPT_ENTRY_ITERATE(table->private->entries, table->private->size,
+			   cleanup_entry, NULL);
+	vfree(table->private);
+	MOD_DEC_USE_COUNT;
+}
+
+/* The built-in targets: standard (NULL) and error. */
+static struct arpt_target arpt_standard_target
+= { { NULL, NULL }, ARPT_STANDARD_TARGET, NULL, NULL, NULL };
+static struct arpt_target arpt_error_target
+= { { NULL, NULL }, ARPT_ERROR_TARGET, arpt_error, NULL, NULL };
+
+static struct nf_sockopt_ops arpt_sockopts
+= { { NULL, NULL }, PF_INET, ARPT_BASE_CTL, ARPT_SO_SET_MAX+1, do_arpt_set_ctl,
+    ARPT_BASE_CTL, ARPT_SO_GET_MAX+1, do_arpt_get_ctl, 0, NULL  };
+
+#ifdef CONFIG_PROC_FS
+static inline int print_name(const struct arpt_table *t,
+			     off_t start_offset, char *buffer, int length,
+			     off_t *pos, unsigned int *count)
+{
+	if ((*count)++ >= start_offset) {
+		unsigned int namelen;
+
+		namelen = sprintf(buffer + *pos, "%s\n", t->name);
+		if (*pos + namelen > length) {
+			/* Stop iterating */
+			return 1;
+		}
+		*pos += namelen;
+	}
+	return 0;
+}
+
+static int arpt_get_tables(char *buffer, char **start, off_t offset, int length)
+{
+	off_t pos = 0;
+	unsigned int count = 0;
+
+	if (down_interruptible(&arpt_mutex) != 0)
+		return 0;
+
+	LIST_FIND(&arpt_tables, print_name, struct arpt_table *,
+		  offset, buffer, length, &pos, &count);
+
+	up(&arpt_mutex);
+
+	/* `start' hack - see fs/proc/generic.c line ~105 */
+	*start=(char *)((unsigned long)count-offset);
+	return pos;
+}
+#endif /*CONFIG_PROC_FS*/
+
+static int __init init(void)
+{
+	int ret;
+
+	/* Noone else will be downing sem now, so we won't sleep */
+	down(&arpt_mutex);
+	list_append(&arpt_target, &arpt_standard_target);
+	list_append(&arpt_target, &arpt_error_target);
+	up(&arpt_mutex);
+
+	/* Register setsockopt */
+	ret = nf_register_sockopt(&arpt_sockopts);
+	if (ret < 0) {
+		duprintf("Unable to register sockopts.\n");
+		return ret;
+	}
+
+#ifdef CONFIG_PROC_FS
+	{
+		struct proc_dir_entry *proc;
+
+		proc = proc_net_create("arp_tables_names", 0, arpt_get_tables);
+		if (!proc) {
+			nf_unregister_sockopt(&arpt_sockopts);
+			return -ENOMEM;
+		}
+		proc->owner = THIS_MODULE;
+	}
+#endif
+
+	printk("arp_tables: (C) 2002 David S. Miller\n");
+	return 0;
+}
+
+static void __exit fini(void)
+{
+	nf_unregister_sockopt(&arpt_sockopts);
+#ifdef CONFIG_PROC_FS
+	proc_net_remove("arp_tables_names");
+#endif
+}
+
+EXPORT_SYMBOL(arpt_register_table);
+EXPORT_SYMBOL(arpt_unregister_table);
+EXPORT_SYMBOL(arpt_do_table);
+EXPORT_SYMBOL(arpt_register_target);
+EXPORT_SYMBOL(arpt_unregister_target);
+
+module_init(init);
+module_exit(fini);
+MODULE_LICENSE("GPL");
FUNET's LINUX-ADM group, linux-adm@nic.funet.fi
TCL-scripts by Sam Shen (who was at: slshen@lbl.gov)