[NETFILTER]: xt_hashlimit match, revision 1

Introduces the xt_hashlimit match revision 1. It adds support for
kernel-level inversion and grouping source and/or destination IP
addresses, allowing to limit on a per-subnet basis. While this would
technically obsolete xt_limit, xt_hashlimit is a more expensive due
to the hashbucketing.

Kernel-level inversion: Previously you had to do user-level inversion:

	iptables -N foo
	iptables -A foo -m hashlimit --hashlimit(-upto) 5/s -j RETURN
	iptables -A foo -j DROP
	iptables -A INPUT -j foo

now it is simpler:

	iptables -A INPUT -m hashlimit --hashlimit-over 5/s -j DROP

Signed-off-by: Jan Engelhardt <jengelh@computergmbh.de>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 286 insertions, 36 deletions

diff --git a/net/netfilter/xt_hashlimit.c b/net/netfilter/xt_hashlimit.c
index b224b8f719a4..54aaf5bac2d7 100644
--- a/net/netfilter/xt_hashlimit.c
+++ b/net/netfilter/xt_hashlimit.c
@@ -1,9 +1,9 @@
-/* iptables match extension to limit the number of packets per second
- * seperately for each hashbucket (sourceip/sourceport/dstip/dstport)
+/*
+ *      xt_hashlimit - Netfilter module to limit the number of packets per time
+ *      seperately for each hashbucket (sourceip/sourceport/dstip/dstport)
  *
- * (C) 2003-2004 by Harald Welte <laforge@netfilter.org>
- *
- * $Id: ipt_hashlimit.c 3244 2004-10-20 16:24:29Z laforge@netfilter.org $
+ *      (C) 2003-2004 by Harald Welte <laforge@netfilter.org>
+ *      Copyright © CC Computer Consultants GmbH, 2007 - 2008
  *
  * Development of this code was funded by Astaro AG, http://www.astaro.com/
  */
@@ -35,6 +35,7 @@
 
 MODULE_LICENSE("GPL");
 MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
+MODULE_AUTHOR("Jan Engelhardt <jengelh@computergmbh.de>");
 MODULE_DESCRIPTION("Xtables: per hash-bucket rate-limit match");
 MODULE_ALIAS("ipt_hashlimit");
 MODULE_ALIAS("ip6t_hashlimit");
@@ -57,7 +58,7 @@ struct dsthash_dst {
                         __be32 dst[4];
                 } ip6;
 #endif
-        } addr;
+        };
         __be16 src_port;
         __be16 dst_port;
 };
@@ -81,7 +82,7 @@ struct xt_hashlimit_htable {
         atomic_t use;
         int family;
 
-        struct hashlimit_cfg cfg;       /* config */
+        struct hashlimit_cfg1 cfg;      /* config */
 
         /* used internally */
         spinlock_t lock;                /* lock for list_head */
@@ -184,7 +185,7 @@ dsthash_free(struct xt_hashlimit_htable *ht, struct dsthash_ent *ent)
 }
 static void htable_gc(unsigned long htlong);
 
-static int htable_create(struct xt_hashlimit_info *minfo, int family)
+static int htable_create_v0(struct xt_hashlimit_info *minfo, int family)
 {
         struct xt_hashlimit_htable *hinfo;
         unsigned int size;
@@ -210,7 +211,18 @@ static int htable_create(struct xt_hashlimit_info *minfo, int family)
         minfo->hinfo = hinfo;
 
         /* copy match config into hashtable config */
-        memcpy(&hinfo->cfg, &minfo->cfg, sizeof(hinfo->cfg));
+        hinfo->cfg.mode        = minfo->cfg.mode;
+        hinfo->cfg.avg         = minfo->cfg.avg;
+        hinfo->cfg.burst       = minfo->cfg.burst;
+        hinfo->cfg.max         = minfo->cfg.max;
+        hinfo->cfg.gc_interval = minfo->cfg.gc_interval;
+        hinfo->cfg.expire      = minfo->cfg.expire;
+
+        if (family == AF_INET)
+                hinfo->cfg.srcmask = hinfo->cfg.dstmask = 32;
+        else
+                hinfo->cfg.srcmask = hinfo->cfg.dstmask = 128;
+
         hinfo->cfg.size = size;
         if (!hinfo->cfg.max)
                 hinfo->cfg.max = 8 * hinfo->cfg.size;
@@ -246,6 +258,70 @@ static int htable_create(struct xt_hashlimit_info *minfo, int family)
         return 0;
 }
 
+static int htable_create(struct xt_hashlimit_mtinfo1 *minfo,
+                         unsigned int family)
+{
+        struct xt_hashlimit_htable *hinfo;
+        unsigned int size;
+        unsigned int i;
+
+        if (minfo->cfg.size) {
+                size = minfo->cfg.size;
+        } else {
+                size = (num_physpages << PAGE_SHIFT) / 16384 /
+                       sizeof(struct list_head);
+                if (num_physpages > 1024 * 1024 * 1024 / PAGE_SIZE)
+                        size = 8192;
+                if (size < 16)
+                        size = 16;
+        }
+        /* FIXME: don't use vmalloc() here or anywhere else -HW */
+        hinfo = vmalloc(sizeof(struct xt_hashlimit_htable) +
+                        sizeof(struct list_head) * size);
+        if (hinfo == NULL) {
+                printk(KERN_ERR "xt_hashlimit: unable to create hashtable\n");
+                return -1;
+        }
+        minfo->hinfo = hinfo;
+
+        /* copy match config into hashtable config */
+        memcpy(&hinfo->cfg, &minfo->cfg, sizeof(hinfo->cfg));
+        hinfo->cfg.size = size;
+        if (hinfo->cfg.max == 0)
+                hinfo->cfg.max = 8 * hinfo->cfg.size;
+        else if (hinfo->cfg.max < hinfo->cfg.size)
+                hinfo->cfg.max = hinfo->cfg.size;
+
+        for (i = 0; i < hinfo->cfg.size; i++)
+                INIT_HLIST_HEAD(&hinfo->hash[i]);
+
+        atomic_set(&hinfo->use, 1);
+        hinfo->count = 0;
+        hinfo->family = family;
+        hinfo->rnd_initialized = 0;
+        spin_lock_init(&hinfo->lock);
+
+        hinfo->pde = create_proc_entry(minfo->name, 0,
+                                       family == AF_INET ? hashlimit_procdir4 :
+                                                           hashlimit_procdir6);
+        if (hinfo->pde == NULL) {
+                vfree(hinfo);
+                return -1;
+        }
+        hinfo->pde->proc_fops = &dl_file_ops;
+        hinfo->pde->data = hinfo;
+
+        setup_timer(&hinfo->timer, htable_gc, (unsigned long)hinfo);
+        hinfo->timer.expires = jiffies + msecs_to_jiffies(hinfo->cfg.gc_interval);
+        add_timer(&hinfo->timer);
+
+        spin_lock_bh(&hashlimit_lock);
+        hlist_add_head(&hinfo->node, &hashlimit_htables);
+        spin_unlock_bh(&hashlimit_lock);
+
+        return 0;
+}
+
 static bool select_all(const struct xt_hashlimit_htable *ht,
                        const struct dsthash_ent *he)
 {
@@ -388,6 +464,46 @@ static inline void rateinfo_recalc(struct dsthash_ent *dh, unsigned long now)
         dh->rateinfo.prev = now;
 }
 
+static inline __be32 maskl(__be32 a, unsigned int l)
+{
+        return htonl(ntohl(a) & ~(~(u_int32_t)0 >> l));
+}
+
+static void hashlimit_ipv6_mask(__be32 *i, unsigned int p)
+{
+        switch (p) {
+        case 0:
+                i[0] = i[1] = 0;
+                i[2] = i[3] = 0;
+                break;
+        case 1 ... 31:
+                i[0] = maskl(i[0], p);
+                i[1] = i[2] = i[3] = 0;
+                break;
+        case 32:
+                i[1] = i[2] = i[3] = 0;
+                break;
+        case 33 ... 63:
+                i[1] = maskl(i[1], p - 32);
+                i[2] = i[3] = 0;
+                break;
+        case 64:
+                i[2] = i[3] = 0;
+                break;
+        case 65 ... 95:
+                i[2] = maskl(i[2], p - 64);
+                i[3] = 0;
+        case 96:
+                i[3] = 0;
+                break;
+        case 97 ... 127:
+                i[3] = maskl(i[3], p - 96);
+                break;
+        case 128:
+                break;
+        }
+}
+
 static int
 hashlimit_init_dst(const struct xt_hashlimit_htable *hinfo,
                    struct dsthash_dst *dst,
@@ -401,9 +517,11 @@ hashlimit_init_dst(const struct xt_hashlimit_htable *hinfo,
         switch (hinfo->family) {
         case AF_INET:
                 if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_DIP)
-                        dst->addr.ip.dst = ip_hdr(skb)->daddr;
+                        dst->ip.dst = maskl(ip_hdr(skb)->daddr,
+                                      hinfo->cfg.dstmask);
                 if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_SIP)
-                        dst->addr.ip.src = ip_hdr(skb)->saddr;
+                        dst->ip.src = maskl(ip_hdr(skb)->saddr,
+                                      hinfo->cfg.srcmask);
 
                 if (!(hinfo->cfg.mode &
                       (XT_HASHLIMIT_HASH_DPT | XT_HASHLIMIT_HASH_SPT)))
@@ -412,12 +530,16 @@ hashlimit_init_dst(const struct xt_hashlimit_htable *hinfo,
                 break;
 #if defined(CONFIG_IP6_NF_IPTABLES) || defined(CONFIG_IP6_NF_IPTABLES_MODULE)
         case AF_INET6:
-                if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_DIP)
-                        memcpy(&dst->addr.ip6.dst, &ipv6_hdr(skb)->daddr,
-                               sizeof(dst->addr.ip6.dst));
-                if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_SIP)
-                        memcpy(&dst->addr.ip6.src, &ipv6_hdr(skb)->saddr,
-                               sizeof(dst->addr.ip6.src));
+                if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_DIP) {
+                        memcpy(&dst->ip6.dst, &ipv6_hdr(skb)->daddr,
+                               sizeof(dst->ip6.dst));
+                        hashlimit_ipv6_mask(dst->ip6.dst, hinfo->cfg.dstmask);
+                }
+                if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_SIP) {
+                        memcpy(&dst->ip6.src, &ipv6_hdr(skb)->saddr,
+                               sizeof(dst->ip6.src));
+                        hashlimit_ipv6_mask(dst->ip6.src, hinfo->cfg.srcmask);
+                }
 
                 if (!(hinfo->cfg.mode &
                       (XT_HASHLIMIT_HASH_DPT | XT_HASHLIMIT_HASH_SPT)))
@@ -457,10 +579,10 @@ hashlimit_init_dst(const struct xt_hashlimit_htable *hinfo,
 }
 
 static bool
-hashlimit_mt(const struct sk_buff *skb, const struct net_device *in,
-             const struct net_device *out, const struct xt_match *match,
-             const void *matchinfo, int offset, unsigned int protoff,
-             bool *hotdrop)
+hashlimit_mt_v0(const struct sk_buff *skb, const struct net_device *in,
+                const struct net_device *out, const struct xt_match *match,
+                const void *matchinfo, int offset, unsigned int protoff,
+                bool *hotdrop)
 {
         const struct xt_hashlimit_info *r =
                 ((const struct xt_hashlimit_info *)matchinfo)->u.master;
@@ -512,9 +634,62 @@ hotdrop:
 }
 
 static bool
-hashlimit_mt_check(const char *tablename, const void *inf,
-                   const struct xt_match *match, void *matchinfo,
-                   unsigned int hook_mask)
+hashlimit_mt(const struct sk_buff *skb, const struct net_device *in,
+             const struct net_device *out, const struct xt_match *match,
+             const void *matchinfo, int offset, unsigned int protoff,
+             bool *hotdrop)
+{
+        const struct xt_hashlimit_mtinfo1 *info = matchinfo;
+        struct xt_hashlimit_htable *hinfo = info->hinfo;
+        unsigned long now = jiffies;
+        struct dsthash_ent *dh;
+        struct dsthash_dst dst;
+
+        if (hashlimit_init_dst(hinfo, &dst, skb, protoff) < 0)
+                goto hotdrop;
+
+        spin_lock_bh(&hinfo->lock);
+        dh = dsthash_find(hinfo, &dst);
+        if (dh == NULL) {
+                dh = dsthash_alloc_init(hinfo, &dst);
+                if (dh == NULL) {
+                        spin_unlock_bh(&hinfo->lock);
+                        goto hotdrop;
+                }
+
+                dh->expires = jiffies + msecs_to_jiffies(hinfo->cfg.expire);
+                dh->rateinfo.prev = jiffies;
+                dh->rateinfo.credit = user2credits(hinfo->cfg.avg *
+                                      hinfo->cfg.burst);
+                dh->rateinfo.credit_cap = user2credits(hinfo->cfg.avg *
+                                          hinfo->cfg.burst);
+                dh->rateinfo.cost = user2credits(hinfo->cfg.avg);
+        } else {
+                /* update expiration timeout */
+                dh->expires = now + msecs_to_jiffies(hinfo->cfg.expire);
+                rateinfo_recalc(dh, now);
+        }
+
+        if (dh->rateinfo.credit >= dh->rateinfo.cost) {
+                /* below the limit */
+                dh->rateinfo.credit -= dh->rateinfo.cost;
+                spin_unlock_bh(&hinfo->lock);
+                return !(info->cfg.mode & XT_HASHLIMIT_INVERT);
+        }
+
+        spin_unlock_bh(&hinfo->lock);
+        /* default match is underlimit - so over the limit, we need to invert */
+        return info->cfg.mode & XT_HASHLIMIT_INVERT;
+
+ hotdrop:
+        *hotdrop = true;
+        return false;
+}
+
+static bool
+hashlimit_mt_check_v0(const char *tablename, const void *inf,
+                      const struct xt_match *match, void *matchinfo,
+                      unsigned int hook_mask)
 {
         struct xt_hashlimit_info *r = matchinfo;
 
@@ -546,7 +721,7 @@ hashlimit_mt_check(const char *tablename, const void *inf,
          * create duplicate proc files. -HW */
         mutex_lock(&hlimit_mutex);
         r->hinfo = htable_find_get(r->name, match->family);
-        if (!r->hinfo && htable_create(r, match->family) != 0) {
+        if (!r->hinfo && htable_create_v0(r, match->family) != 0) {
                 mutex_unlock(&hlimit_mutex);
                 return false;
         }
@@ -557,14 +732,68 @@ hashlimit_mt_check(const char *tablename, const void *inf,
         return true;
 }
 
+static bool
+hashlimit_mt_check(const char *tablename, const void *inf,
+                   const struct xt_match *match, void *matchinfo,
+                   unsigned int hook_mask)
+{
+        struct xt_hashlimit_mtinfo1 *info = matchinfo;
+
+        /* Check for overflow. */
+        if (info->cfg.burst == 0 ||
+            user2credits(info->cfg.avg * info->cfg.burst) <
+            user2credits(info->cfg.avg)) {
+                printk(KERN_ERR "xt_hashlimit: overflow, try lower: %u/%u\n",
+                       info->cfg.avg, info->cfg.burst);
+                return false;
+        }
+        if (info->cfg.gc_interval == 0 || info->cfg.expire == 0)
+                return false;
+        if (info->name[sizeof(info->name)-1] != '\0')
+                return false;
+        if (match->family == AF_INET) {
+                if (info->cfg.srcmask > 32 || info->cfg.dstmask > 32)
+                        return false;
+        } else {
+                if (info->cfg.srcmask > 128 || info->cfg.dstmask > 128)
+                        return false;
+        }
+
+        /* This is the best we've got: We cannot release and re-grab lock,
+         * since checkentry() is called before x_tables.c grabs xt_mutex.
+         * We also cannot grab the hashtable spinlock, since htable_create will
+         * call vmalloc, and that can sleep.  And we cannot just re-search
+         * the list of htable's in htable_create(), since then we would
+         * create duplicate proc files. -HW */
+        mutex_lock(&hlimit_mutex);
+        info->hinfo = htable_find_get(info->name, match->family);
+        if (!info->hinfo && htable_create(info, match->family) != 0) {
+                mutex_unlock(&hlimit_mutex);
+                return false;
+        }
+        mutex_unlock(&hlimit_mutex);
+
+        /* Ugly hack: For SMP, we only want to use one set */
+        info->master = info;
+        return true;
+}
+
 static void
-hashlimit_mt_destroy(const struct xt_match *match, void *matchinfo)
+hashlimit_mt_destroy_v0(const struct xt_match *match, void *matchinfo)
 {
         const struct xt_hashlimit_info *r = matchinfo;
 
         htable_put(r->hinfo);
 }
 
+static void
+hashlimit_mt_destroy(const struct xt_match *match, void *matchinfo)
+{
+        const struct xt_hashlimit_mtinfo1 *info = matchinfo;
+
+        htable_put(info->hinfo);
+}
+
 #ifdef CONFIG_COMPAT
 struct compat_xt_hashlimit_info {
         char name[IFNAMSIZ];
@@ -592,33 +821,54 @@ static int hashlimit_mt_compat_to_user(void __user *dst, void *src)
 static struct xt_match hashlimit_mt_reg[] __read_mostly = {
         {
                 .name           = "hashlimit",
+                .revision       = 0,
                 .family         = AF_INET,
-                .match          = hashlimit_mt,
+                .match          = hashlimit_mt_v0,
                 .matchsize      = sizeof(struct xt_hashlimit_info),
 #ifdef CONFIG_COMPAT
                 .compatsize     = sizeof(struct compat_xt_hashlimit_info),
                 .compat_from_user = hashlimit_mt_compat_from_user,
                 .compat_to_user = hashlimit_mt_compat_to_user,
 #endif
-                .checkentry     = hashlimit_mt_check,
-                .destroy        = hashlimit_mt_destroy,
+                .checkentry     = hashlimit_mt_check_v0,
+                .destroy        = hashlimit_mt_destroy_v0,
                 .me             = THIS_MODULE
         },
+        {
+                .name           = "hashlimit",
+                .revision       = 1,
+                .family         = AF_INET,
+                .match          = hashlimit_mt,
+                .matchsize      = sizeof(struct xt_hashlimit_mtinfo1),
+                .checkentry     = hashlimit_mt_check,
+                .destroy        = hashlimit_mt_destroy,
+                .me             = THIS_MODULE,
+        },
 #if defined(CONFIG_IP6_NF_IPTABLES) || defined(CONFIG_IP6_NF_IPTABLES_MODULE)
         {
                 .name           = "hashlimit",
                 .family         = AF_INET6,
-                .match          = hashlimit_mt,
+                .match          = hashlimit_mt_v0,
                 .matchsize      = sizeof(struct xt_hashlimit_info),
 #ifdef CONFIG_COMPAT
                 .compatsize     = sizeof(struct compat_xt_hashlimit_info),
                 .compat_from_user = hashlimit_mt_compat_from_user,
                 .compat_to_user = hashlimit_mt_compat_to_user,
 #endif
-                .checkentry     = hashlimit_mt_check,
-                .destroy        = hashlimit_mt_destroy,
+                .checkentry     = hashlimit_mt_check_v0,
+                .destroy        = hashlimit_mt_destroy_v0,
                 .me             = THIS_MODULE
         },
+        {
+                .name           = "hashlimit",
+                .revision       = 1,
+                .family         = AF_INET6,
+                .match          = hashlimit_mt,
+                .matchsize      = sizeof(struct xt_hashlimit_mtinfo1),
+                .checkentry     = hashlimit_mt_check,
+                .destroy        = hashlimit_mt_destroy,
+                .me             = THIS_MODULE,
+        },
 #endif
 };
 
@@ -678,9 +928,9 @@ static int dl_seq_real_show(struct dsthash_ent *ent, int family,
                 return seq_printf(s, "%ld %u.%u.%u.%u:%u->"
                                      "%u.%u.%u.%u:%u %u %u %u\n",
                                  (long)(ent->expires - jiffies)/HZ,
-                                 NIPQUAD(ent->dst.addr.ip.src),
+                                 NIPQUAD(ent->dst.ip.src),
                                  ntohs(ent->dst.src_port),
-                                 NIPQUAD(ent->dst.addr.ip.dst),
+                                 NIPQUAD(ent->dst.ip.dst),
                                  ntohs(ent->dst.dst_port),
                                  ent->rateinfo.credit, ent->rateinfo.credit_cap,
                                  ent->rateinfo.cost);
@@ -689,9 +939,9 @@ static int dl_seq_real_show(struct dsthash_ent *ent, int family,
                 return seq_printf(s, "%ld " NIP6_FMT ":%u->"
                                      NIP6_FMT ":%u %u %u %u\n",
                                  (long)(ent->expires - jiffies)/HZ,
-                                 NIP6(*(struct in6_addr *)&ent->dst.addr.ip6.src),
+                                 NIP6(*(struct in6_addr *)&ent->dst.ip6.src),
                                  ntohs(ent->dst.src_port),
-                                 NIP6(*(struct in6_addr *)&ent->dst.addr.ip6.dst),
+                                 NIP6(*(struct in6_addr *)&ent->dst.ip6.dst),
                                  ntohs(ent->dst.dst_port),
                                  ent->rateinfo.credit, ent->rateinfo.credit_cap,
                                  ent->rateinfo.cost);