[NETFILTER] x_tables: Abstraction layer for {ip,ip6,arp}_tables
This monster-patch tries to do the best job for unifying the data
structures and backend interfaces for the three evil clones ip_tables,
ip6_tables and arp_tables. In an ideal world we would never have
allowed this kind of copy+paste programming... but well, our world
isn't (yet?) ideal.
o introduce a new x_tables module
o {ip,arp,ip6}_tables depend on this x_tables module
o registration functions for tables, matches and targets are only
wrappers around x_tables provided functions
o all matches/targets that are used from ip_tables and ip6_tables
are now implemented as xt_FOOBAR.c files and provide module aliases
to ipt_FOOBAR and ip6t_FOOBAR
o header files for xt_matches are in include/linux/netfilter/,
include/linux/netfilter_{ipv4,ipv6} contains compatibility wrappers
around the xt_FOOBAR.h headers
Based on this patchset we're going to further unify the code,
gradually getting rid of all the layer 3 specific assumptions.
Signed-off-by: Harald Welte <laforge@netfilter.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
2006-01-12 21:30:04 +00:00
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#include <linux/types.h>
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#include <linux/module.h>
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#include <net/ip.h>
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2006-01-14 00:19:44 +00:00
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#include <linux/ipv6.h>
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[NETFILTER] x_tables: Abstraction layer for {ip,ip6,arp}_tables
This monster-patch tries to do the best job for unifying the data
structures and backend interfaces for the three evil clones ip_tables,
ip6_tables and arp_tables. In an ideal world we would never have
allowed this kind of copy+paste programming... but well, our world
isn't (yet?) ideal.
o introduce a new x_tables module
o {ip,arp,ip6}_tables depend on this x_tables module
o registration functions for tables, matches and targets are only
wrappers around x_tables provided functions
o all matches/targets that are used from ip_tables and ip6_tables
are now implemented as xt_FOOBAR.c files and provide module aliases
to ipt_FOOBAR and ip6t_FOOBAR
o header files for xt_matches are in include/linux/netfilter/,
include/linux/netfilter_{ipv4,ipv6} contains compatibility wrappers
around the xt_FOOBAR.h headers
Based on this patchset we're going to further unify the code,
gradually getting rid of all the layer 3 specific assumptions.
Signed-off-by: Harald Welte <laforge@netfilter.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
2006-01-12 21:30:04 +00:00
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#include <net/ipv6.h>
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#include <net/tcp.h>
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#include <net/udp.h>
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#include <linux/netfilter/x_tables.h>
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#include <linux/netfilter/xt_tcpudp.h>
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#include <linux/netfilter_ipv4/ip_tables.h>
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#include <linux/netfilter_ipv6/ip6_tables.h>
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MODULE_DESCRIPTION("x_tables match for TCP and UDP, supports IPv4 and IPv6");
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MODULE_LICENSE("GPL");
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MODULE_ALIAS("xt_tcp");
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MODULE_ALIAS("xt_udp");
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MODULE_ALIAS("ipt_udp");
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MODULE_ALIAS("ipt_tcp");
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MODULE_ALIAS("ip6t_udp");
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MODULE_ALIAS("ip6t_tcp");
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#ifdef DEBUG_IP_FIREWALL_USER
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#define duprintf(format, args...) printk(format , ## args)
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#else
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#define duprintf(format, args...)
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#endif
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/* Returns 1 if the port is matched by the range, 0 otherwise */
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static inline int
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port_match(u_int16_t min, u_int16_t max, u_int16_t port, int invert)
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{
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int ret;
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ret = (port >= min && port <= max) ^ invert;
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return ret;
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}
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static int
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tcp_find_option(u_int8_t option,
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const struct sk_buff *skb,
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unsigned int protoff,
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unsigned int optlen,
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int invert,
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int *hotdrop)
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{
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/* tcp.doff is only 4 bits, ie. max 15 * 4 bytes */
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u_int8_t _opt[60 - sizeof(struct tcphdr)], *op;
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unsigned int i;
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duprintf("tcp_match: finding option\n");
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if (!optlen)
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return invert;
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/* If we don't have the whole header, drop packet. */
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op = skb_header_pointer(skb, protoff + sizeof(struct tcphdr),
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optlen, _opt);
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if (op == NULL) {
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*hotdrop = 1;
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return 0;
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}
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for (i = 0; i < optlen; ) {
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if (op[i] == option) return !invert;
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if (op[i] < 2) i++;
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else i += op[i+1]?:1;
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}
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return invert;
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}
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static int
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tcp_match(const struct sk_buff *skb,
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const struct net_device *in,
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const struct net_device *out,
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const void *matchinfo,
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int offset,
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unsigned int protoff,
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int *hotdrop)
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{
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struct tcphdr _tcph, *th;
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const struct xt_tcp *tcpinfo = matchinfo;
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if (offset) {
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/* To quote Alan:
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Don't allow a fragment of TCP 8 bytes in. Nobody normal
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causes this. Its a cracker trying to break in by doing a
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flag overwrite to pass the direction checks.
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*/
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if (offset == 1) {
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duprintf("Dropping evil TCP offset=1 frag.\n");
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*hotdrop = 1;
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}
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/* Must not be a fragment. */
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return 0;
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}
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#define FWINVTCP(bool,invflg) ((bool) ^ !!(tcpinfo->invflags & invflg))
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th = skb_header_pointer(skb, protoff, sizeof(_tcph), &_tcph);
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if (th == NULL) {
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/* We've been asked to examine this packet, and we
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can't. Hence, no choice but to drop. */
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duprintf("Dropping evil TCP offset=0 tinygram.\n");
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*hotdrop = 1;
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return 0;
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}
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if (!port_match(tcpinfo->spts[0], tcpinfo->spts[1],
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ntohs(th->source),
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!!(tcpinfo->invflags & XT_TCP_INV_SRCPT)))
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return 0;
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if (!port_match(tcpinfo->dpts[0], tcpinfo->dpts[1],
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ntohs(th->dest),
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!!(tcpinfo->invflags & XT_TCP_INV_DSTPT)))
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return 0;
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if (!FWINVTCP((((unsigned char *)th)[13] & tcpinfo->flg_mask)
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== tcpinfo->flg_cmp,
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XT_TCP_INV_FLAGS))
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return 0;
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if (tcpinfo->option) {
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if (th->doff * 4 < sizeof(_tcph)) {
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*hotdrop = 1;
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return 0;
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}
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if (!tcp_find_option(tcpinfo->option, skb, protoff,
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th->doff*4 - sizeof(_tcph),
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tcpinfo->invflags & XT_TCP_INV_OPTION,
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hotdrop))
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return 0;
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}
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return 1;
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}
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/* Called when user tries to insert an entry of this type. */
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static int
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tcp_checkentry(const char *tablename,
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const void *info,
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void *matchinfo,
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unsigned int matchsize,
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unsigned int hook_mask)
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{
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const struct ipt_ip *ip = info;
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const struct xt_tcp *tcpinfo = matchinfo;
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/* Must specify proto == TCP, and no unknown invflags */
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return ip->proto == IPPROTO_TCP
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&& !(ip->invflags & XT_INV_PROTO)
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&& matchsize == XT_ALIGN(sizeof(struct xt_tcp))
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&& !(tcpinfo->invflags & ~XT_TCP_INV_MASK);
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}
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/* Called when user tries to insert an entry of this type. */
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static int
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tcp6_checkentry(const char *tablename,
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const void *entry,
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void *matchinfo,
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unsigned int matchsize,
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unsigned int hook_mask)
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{
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const struct ip6t_ip6 *ipv6 = entry;
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const struct xt_tcp *tcpinfo = matchinfo;
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/* Must specify proto == TCP, and no unknown invflags */
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return ipv6->proto == IPPROTO_TCP
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&& !(ipv6->invflags & XT_INV_PROTO)
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&& matchsize == XT_ALIGN(sizeof(struct xt_tcp))
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&& !(tcpinfo->invflags & ~XT_TCP_INV_MASK);
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}
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static int
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udp_match(const struct sk_buff *skb,
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const struct net_device *in,
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const struct net_device *out,
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const void *matchinfo,
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int offset,
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unsigned int protoff,
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int *hotdrop)
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{
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struct udphdr _udph, *uh;
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const struct xt_udp *udpinfo = matchinfo;
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/* Must not be a fragment. */
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if (offset)
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return 0;
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uh = skb_header_pointer(skb, protoff, sizeof(_udph), &_udph);
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if (uh == NULL) {
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/* We've been asked to examine this packet, and we
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can't. Hence, no choice but to drop. */
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duprintf("Dropping evil UDP tinygram.\n");
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*hotdrop = 1;
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return 0;
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}
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return port_match(udpinfo->spts[0], udpinfo->spts[1],
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ntohs(uh->source),
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!!(udpinfo->invflags & XT_UDP_INV_SRCPT))
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&& port_match(udpinfo->dpts[0], udpinfo->dpts[1],
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ntohs(uh->dest),
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!!(udpinfo->invflags & XT_UDP_INV_DSTPT));
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}
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/* Called when user tries to insert an entry of this type. */
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static int
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udp_checkentry(const char *tablename,
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const void *info,
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void *matchinfo,
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unsigned int matchinfosize,
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unsigned int hook_mask)
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{
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const struct ipt_ip *ip = info;
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const struct xt_udp *udpinfo = matchinfo;
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/* Must specify proto == UDP, and no unknown invflags */
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if (ip->proto != IPPROTO_UDP || (ip->invflags & XT_INV_PROTO)) {
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duprintf("ipt_udp: Protocol %u != %u\n", ip->proto,
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IPPROTO_UDP);
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return 0;
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}
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if (matchinfosize != XT_ALIGN(sizeof(struct xt_udp))) {
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duprintf("ipt_udp: matchsize %u != %u\n",
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matchinfosize, XT_ALIGN(sizeof(struct xt_udp)));
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return 0;
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}
|
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if (udpinfo->invflags & ~XT_UDP_INV_MASK) {
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duprintf("ipt_udp: unknown flags %X\n",
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|
udpinfo->invflags);
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return 0;
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}
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return 1;
|
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|
}
|
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/* Called when user tries to insert an entry of this type. */
|
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|
static int
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udp6_checkentry(const char *tablename,
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|
|
const void *entry,
|
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|
void *matchinfo,
|
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|
unsigned int matchinfosize,
|
|
|
|
unsigned int hook_mask)
|
|
|
|
{
|
|
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const struct ip6t_ip6 *ipv6 = entry;
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const struct xt_udp *udpinfo = matchinfo;
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|
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|
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/* Must specify proto == UDP, and no unknown invflags */
|
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|
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if (ipv6->proto != IPPROTO_UDP || (ipv6->invflags & XT_INV_PROTO)) {
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|
|
|
duprintf("ip6t_udp: Protocol %u != %u\n", ipv6->proto,
|
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|
|
IPPROTO_UDP);
|
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|
return 0;
|
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|
}
|
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|
|
if (matchinfosize != XT_ALIGN(sizeof(struct xt_udp))) {
|
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|
duprintf("ip6t_udp: matchsize %u != %u\n",
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matchinfosize, XT_ALIGN(sizeof(struct xt_udp)));
|
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return 0;
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}
|
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|
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if (udpinfo->invflags & ~XT_UDP_INV_MASK) {
|
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|
|
duprintf("ip6t_udp: unknown flags %X\n",
|
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udpinfo->invflags);
|
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return 0;
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}
|
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|
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return 1;
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}
|
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static struct xt_match tcp_matchstruct = {
|
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.name = "tcp",
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.match = &tcp_match,
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|
.checkentry = &tcp_checkentry,
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|
.me = THIS_MODULE,
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};
|
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static struct xt_match tcp6_matchstruct = {
|
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.name = "tcp",
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.match = &tcp_match,
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.checkentry = &tcp6_checkentry,
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.me = THIS_MODULE,
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};
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static struct xt_match udp_matchstruct = {
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.name = "udp",
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.match = &udp_match,
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.checkentry = &udp_checkentry,
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|
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.me = THIS_MODULE,
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};
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static struct xt_match udp6_matchstruct = {
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.name = "udp",
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.match = &udp_match,
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|
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.checkentry = &udp6_checkentry,
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.me = THIS_MODULE,
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|
};
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|
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static int __init init(void)
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|
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{
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|
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int ret;
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|
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ret = xt_register_match(AF_INET, &tcp_matchstruct);
|
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|
|
if (ret)
|
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|
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return ret;
|
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|
|
|
|
|
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ret = xt_register_match(AF_INET6, &tcp6_matchstruct);
|
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|
|
if (ret)
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goto out_unreg_tcp;
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|
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ret = xt_register_match(AF_INET, &udp_matchstruct);
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|
|
if (ret)
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|
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goto out_unreg_tcp6;
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|
|
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ret = xt_register_match(AF_INET6, &udp6_matchstruct);
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|
|
if (ret)
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goto out_unreg_udp;
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|
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|
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return ret;
|
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|
|
|
|
|
|
out_unreg_udp:
|
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|
|
xt_unregister_match(AF_INET, &tcp_matchstruct);
|
|
|
|
out_unreg_tcp6:
|
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|
|
xt_unregister_match(AF_INET6, &tcp6_matchstruct);
|
|
|
|
out_unreg_tcp:
|
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|
|
xt_unregister_match(AF_INET, &tcp_matchstruct);
|
|
|
|
return ret;
|
|
|
|
}
|
|
|
|
|
|
|
|
static void __exit fini(void)
|
|
|
|
{
|
|
|
|
xt_unregister_match(AF_INET6, &udp6_matchstruct);
|
|
|
|
xt_unregister_match(AF_INET, &udp_matchstruct);
|
|
|
|
xt_unregister_match(AF_INET6, &tcp6_matchstruct);
|
|
|
|
xt_unregister_match(AF_INET, &tcp_matchstruct);
|
|
|
|
}
|
|
|
|
|
|
|
|
module_init(init);
|
|
|
|
module_exit(fini);
|