From 0cc37ceccd6056a72b9e4a7a65a8b0fc317be751 Mon Sep 17 00:00:00 2001 From: gborowiak Date: Sun, 7 Sep 2003 13:16:26 +0000 Subject: - variable size of the pool of addresses, no limit to 256 - IP/MAC correspondences matching available - negation mark '!' handled NOTE: incompatible with older version! --- kernel/linux/net/bridge/netfilter/ebt_among.c | 152 ++++++++++++++++++++++---- 1 file changed, 132 insertions(+), 20 deletions(-) (limited to 'kernel/linux/net') diff --git a/kernel/linux/net/bridge/netfilter/ebt_among.c b/kernel/linux/net/bridge/netfilter/ebt_among.c index e69246a..b4f2aed 100644 --- a/kernel/linux/net/bridge/netfilter/ebt_among.c +++ b/kernel/linux/net/bridge/netfilter/ebt_among.c @@ -10,9 +10,13 @@ #include #include +#include +#include #include -static int ebt_mac_wormhash_contains(const struct ebt_mac_wormhash *wh, const char *mac) +#define DEBUG + +static int ebt_mac_wormhash_contains(const struct ebt_mac_wormhash *wh, const char *mac, uint32_t ip) { /* You may be puzzled as to how this code works. * Some tricks were used, refer to include/linux/netfilter_bridge/ebt_among.h @@ -25,11 +29,25 @@ static int ebt_mac_wormhash_contains(const struct ebt_mac_wormhash *wh, const ch int key = (const unsigned char)mac[5]; memcpy(((char*)cmp)+2, mac, 6); offset = wh->table[key]; - while (offset) { - p = (const struct ebt_mac_wormhash_tuple*)(base + offset); - if (cmp[1] == p->cmp[1] && cmp[0] == p->cmp[0]) - return 1; - offset = p->next_ofs; + if (ip) { + while (offset) { + p = (const struct ebt_mac_wormhash_tuple*)(base + offset); + if (cmp[1] == p->cmp[1] && cmp[0] == p->cmp[0]) { + if (p->ip == 0 || p->ip == ip) { + return 1; + } + } + offset = p->next_ofs; + } + } + else { + while (offset) { + p = (const struct ebt_mac_wormhash_tuple*)(base + offset); + if (cmp[1] == p->cmp[1] && cmp[0] == p->cmp[0]) { + return 1; + } + offset = p->next_ofs; + } } return 0; } @@ -46,36 +64,124 @@ static int ebt_mac_wormhash_check_integrity(const struct ebt_mac_wormhash *wh) offset = wh->table[i]; while (offset) { p = (const struct ebt_mac_wormhash_tuple*)(base + offset); - if (p < wh->pool) + if (p < wh->pool) { + printk(KERN_WARNING "ebtables: among: integrity: offset too low; 0x%08x\n", offset); return -1; - if (p > wh->pool + 256 - 1) + } + if (p > wh->pool + wh->poolsize - 1) { + printk(KERN_WARNING "ebtables: among: integrity: offset too high; 0x%08x\n", offset); return -2; + } count++; - if (count > 1000) + if (count > 1000) { + printk(KERN_WARNING "ebtables: among: integrity: loop at %d\n", i); return -3; + } offset = p->next_ofs; } } return 0; } +static int get_ip_dst(const struct sk_buff *skb, uint32_t *addr) +{ + if (skb->mac.ethernet->h_proto == __constant_htons(ETH_P_IP)) { + *addr = skb->nh.iph->daddr; + return 1; + } + if (skb->mac.ethernet->h_proto == __constant_htons(ETH_P_ARP)) { + + uint32_t arp_len = sizeof(struct arphdr) + + (2 * (((*skb).nh.arph)->ar_hln)) + + (2 * (((*skb).nh.arph)->ar_pln)); + + // Make sure the packet is long enough. + if ((((*skb).nh.raw) + arp_len) > (*skb).tail) + return 0; + // IPv4 addresses are always 4 bytes. + if (((*skb).nh.arph)->ar_pln != sizeof(uint32_t)) + return 0; + + memcpy(addr, ((*skb).nh.raw) + sizeof(struct arphdr) + + (2*(((*skb).nh.arph)->ar_hln)) + + (((*skb).nh.arph)->ar_pln), sizeof(uint32_t)); + + return 2; + } + return 0; +} + +static int get_ip_src(const struct sk_buff *skb, uint32_t *addr) +{ + if (skb->mac.ethernet->h_proto == __constant_htons(ETH_P_IP)) { + *addr = skb->nh.iph->saddr; + return 1; + } + if (skb->mac.ethernet->h_proto == __constant_htons(ETH_P_ARP)) { + + uint32_t arp_len = sizeof(struct arphdr) + + (2 * (((*skb).nh.arph)->ar_hln)) + + (2 * (((*skb).nh.arph)->ar_pln)); + + // Make sure the packet is long enough. + if ((((*skb).nh.raw) + arp_len) > (*skb).tail) + return 0; + // IPv4 addresses are always 4 bytes. + if (((*skb).nh.arph)->ar_pln != sizeof(uint32_t)) + return 0; + + memcpy(addr, ((*skb).nh.raw) + sizeof(struct arphdr) + + ((((*skb).nh.arph)->ar_hln)), sizeof(uint32_t)); + + return 2; + } + return 0; +} + static int ebt_filter_among(const struct sk_buff *skb, const struct net_device *in, const struct net_device *out, const void *data, unsigned int datalen) { struct ebt_among_info *info = (struct ebt_among_info *) data; - const char *dmac, *smac; - if (info->bitmask & EBT_AMONG_SRC) { + const struct ebt_mac_wormhash *wh_dst, *wh_src; + uint32_t dip=0, sip=0; + + wh_dst = ebt_among_wh_dst(info); + wh_src = ebt_among_wh_src(info); + + if (wh_src) { smac = skb->mac.ethernet->h_source; - if (!ebt_mac_wormhash_contains(&info->wh_src, smac)) - return EBT_NOMATCH; + get_ip_src(skb, &sip); + if (!(info->bitmask & EBT_AMONG_SRC_NEG)) { + /* we match only if it contains */ + if (!ebt_mac_wormhash_contains(wh_src, smac, sip)) { + return EBT_NOMATCH; + } + } + else { + /* we match only if it DOES NOT contain */ + if (ebt_mac_wormhash_contains(wh_src, smac, sip)) { + return EBT_NOMATCH; + } + } } - if (info->bitmask & EBT_AMONG_DST) { + if (wh_dst) { dmac = skb->mac.ethernet->h_dest; - if (!ebt_mac_wormhash_contains(&info->wh_dst, dmac)) - return EBT_NOMATCH; + get_ip_dst(skb, &dip); + if (!(info->bitmask & EBT_AMONG_DST_NEG)) { + /* we match only if it contains */ + if (!ebt_mac_wormhash_contains(wh_dst, dmac, dip)) { + return EBT_NOMATCH; + } + } + else { + /* we match only if it DOES NOT contain */ + if (ebt_mac_wormhash_contains(wh_dst, dmac, dip)) { + return EBT_NOMATCH; + } + } } return EBT_MATCH; @@ -85,16 +191,22 @@ static int ebt_among_check(const char *tablename, unsigned int hookmask, const struct ebt_entry *e, void *data, unsigned int datalen) { struct ebt_among_info *info = (struct ebt_among_info *) data; + int expected_length = sizeof(struct ebt_among_info); + const struct ebt_mac_wormhash *wh_dst, *wh_src; + wh_dst = ebt_among_wh_dst(info); + wh_src = ebt_among_wh_src(info); + expected_length += ebt_mac_wormhash_size(wh_dst); + expected_length += ebt_mac_wormhash_size(wh_src); - if (datalen != EBT_ALIGN(sizeof(struct ebt_among_info))) { - printk(KERN_WARNING "ebtables: among: wrong size\n"); + if (datalen < EBT_ALIGN(expected_length)) { + printk(KERN_WARNING "ebtables: among: wrong size: %d against expected %d, rounded to %d\n", datalen, expected_length, EBT_ALIGN(expected_length)); return -EINVAL; } - if ((info->bitmask & EBT_AMONG_DST) && ebt_mac_wormhash_check_integrity(&info->wh_dst)) { + if (wh_dst && ebt_mac_wormhash_check_integrity(wh_dst)) { printk(KERN_WARNING "ebtables: among: dst integrity fail\n"); return -EINVAL; } - if ((info->bitmask & EBT_AMONG_SRC) && ebt_mac_wormhash_check_integrity(&info->wh_src)) { + if (wh_src && ebt_mac_wormhash_check_integrity(wh_src)) { printk(KERN_WARNING "ebtables: among: src integrity fail\n"); return -EINVAL; } -- cgit v1.2.3