[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>
diff --git a/net/netfilter/xt_sctp.c b/net/netfilter/xt_sctp.c
new file mode 100644
index 0000000..10fbfc5
--- /dev/null
+++ b/net/netfilter/xt_sctp.c
@@ -0,0 +1,250 @@
+#include <linux/module.h>
+#include <linux/skbuff.h>
+#include <net/ip.h>
+#include <net/ipv6.h>
+#include <linux/sctp.h>
+
+#include <linux/netfilter/x_tables.h>
+#include <linux/netfilter/xt_sctp.h>
+#include <linux/netfilter_ipv4/ip_tables.h>
+#include <linux/netfilter_ipv6/ip6_tables.h>
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Kiran Kumar Immidi");
+MODULE_DESCRIPTION("Match for SCTP protocol packets");
+MODULE_ALIAS("ipt_sctp");
+
+#ifdef DEBUG_SCTP
+#define duprintf(format, args...) printk(format , ## args)
+#else
+#define duprintf(format, args...)
+#endif
+
+#define SCCHECK(cond, option, flag, invflag) (!((flag) & (option)) \
+ || (!!((invflag) & (option)) ^ (cond)))
+
+static int
+match_flags(const struct xt_sctp_flag_info *flag_info,
+ const int flag_count,
+ u_int8_t chunktype,
+ u_int8_t chunkflags)
+{
+ int i;
+
+ for (i = 0; i < flag_count; i++) {
+ if (flag_info[i].chunktype == chunktype) {
+ return (chunkflags & flag_info[i].flag_mask) == flag_info[i].flag;
+ }
+ }
+
+ return 1;
+}
+
+static inline int
+match_packet(const struct sk_buff *skb,
+ unsigned int offset,
+ const u_int32_t *chunkmap,
+ int chunk_match_type,
+ const struct xt_sctp_flag_info *flag_info,
+ const int flag_count,
+ int *hotdrop)
+{
+ u_int32_t chunkmapcopy[256 / sizeof (u_int32_t)];
+ sctp_chunkhdr_t _sch, *sch;
+
+#ifdef DEBUG_SCTP
+ int i = 0;
+#endif
+
+ if (chunk_match_type == SCTP_CHUNK_MATCH_ALL) {
+ SCTP_CHUNKMAP_COPY(chunkmapcopy, chunkmap);
+ }
+
+ do {
+ sch = skb_header_pointer(skb, offset, sizeof(_sch), &_sch);
+ if (sch == NULL) {
+ duprintf("Dropping invalid SCTP packet.\n");
+ *hotdrop = 1;
+ return 0;
+ }
+
+ duprintf("Chunk num: %d\toffset: %d\ttype: %d\tlength: %d\tflags: %x\n",
+ ++i, offset, sch->type, htons(sch->length), sch->flags);
+
+ offset += (htons(sch->length) + 3) & ~3;
+
+ duprintf("skb->len: %d\toffset: %d\n", skb->len, offset);
+
+ if (SCTP_CHUNKMAP_IS_SET(chunkmap, sch->type)) {
+ switch (chunk_match_type) {
+ case SCTP_CHUNK_MATCH_ANY:
+ if (match_flags(flag_info, flag_count,
+ sch->type, sch->flags)) {
+ return 1;
+ }
+ break;
+
+ case SCTP_CHUNK_MATCH_ALL:
+ if (match_flags(flag_info, flag_count,
+ sch->type, sch->flags)) {
+ SCTP_CHUNKMAP_CLEAR(chunkmapcopy, sch->type);
+ }
+ break;
+
+ case SCTP_CHUNK_MATCH_ONLY:
+ if (!match_flags(flag_info, flag_count,
+ sch->type, sch->flags)) {
+ return 0;
+ }
+ break;
+ }
+ } else {
+ switch (chunk_match_type) {
+ case SCTP_CHUNK_MATCH_ONLY:
+ return 0;
+ }
+ }
+ } while (offset < skb->len);
+
+ switch (chunk_match_type) {
+ case SCTP_CHUNK_MATCH_ALL:
+ return SCTP_CHUNKMAP_IS_CLEAR(chunkmap);
+ case SCTP_CHUNK_MATCH_ANY:
+ return 0;
+ case SCTP_CHUNK_MATCH_ONLY:
+ return 1;
+ }
+
+ /* This will never be reached, but required to stop compiler whine */
+ return 0;
+}
+
+static int
+match(const struct sk_buff *skb,
+ const struct net_device *in,
+ const struct net_device *out,
+ const void *matchinfo,
+ int offset,
+ unsigned int protoff,
+ int *hotdrop)
+{
+ const struct xt_sctp_info *info;
+ sctp_sctphdr_t _sh, *sh;
+
+ info = (const struct xt_sctp_info *)matchinfo;
+
+ if (offset) {
+ duprintf("Dropping non-first fragment.. FIXME\n");
+ return 0;
+ }
+
+ sh = skb_header_pointer(skb, protoff, sizeof(_sh), &_sh);
+ if (sh == NULL) {
+ duprintf("Dropping evil TCP offset=0 tinygram.\n");
+ *hotdrop = 1;
+ return 0;
+ }
+ duprintf("spt: %d\tdpt: %d\n", ntohs(sh->source), ntohs(sh->dest));
+
+ return SCCHECK(((ntohs(sh->source) >= info->spts[0])
+ && (ntohs(sh->source) <= info->spts[1])),
+ XT_SCTP_SRC_PORTS, info->flags, info->invflags)
+ && SCCHECK(((ntohs(sh->dest) >= info->dpts[0])
+ && (ntohs(sh->dest) <= info->dpts[1])),
+ XT_SCTP_DEST_PORTS, info->flags, info->invflags)
+ && SCCHECK(match_packet(skb, protoff,
+ info->chunkmap, info->chunk_match_type,
+ info->flag_info, info->flag_count,
+ hotdrop),
+ XT_SCTP_CHUNK_TYPES, info->flags, info->invflags);
+}
+
+static int
+checkentry(const char *tablename,
+ const void *inf,
+ void *matchinfo,
+ unsigned int matchsize,
+ unsigned int hook_mask)
+{
+ const struct xt_sctp_info *info;
+ const struct ipt_ip *ip = inf;
+
+ info = (const struct xt_sctp_info *)matchinfo;
+
+ return ip->proto == IPPROTO_SCTP
+ && !(ip->invflags & XT_INV_PROTO)
+ && matchsize == XT_ALIGN(sizeof(struct xt_sctp_info))
+ && !(info->flags & ~XT_SCTP_VALID_FLAGS)
+ && !(info->invflags & ~XT_SCTP_VALID_FLAGS)
+ && !(info->invflags & ~info->flags)
+ && ((!(info->flags & XT_SCTP_CHUNK_TYPES)) ||
+ (info->chunk_match_type &
+ (SCTP_CHUNK_MATCH_ALL
+ | SCTP_CHUNK_MATCH_ANY
+ | SCTP_CHUNK_MATCH_ONLY)));
+}
+
+static int
+checkentry6(const char *tablename,
+ const void *inf,
+ void *matchinfo,
+ unsigned int matchsize,
+ unsigned int hook_mask)
+{
+ const struct xt_sctp_info *info;
+ const struct ip6t_ip6 *ip = inf;
+
+ info = (const struct xt_sctp_info *)matchinfo;
+
+ return ip->proto == IPPROTO_SCTP
+ && !(ip->invflags & XT_INV_PROTO)
+ && matchsize == XT_ALIGN(sizeof(struct xt_sctp_info))
+ && !(info->flags & ~XT_SCTP_VALID_FLAGS)
+ && !(info->invflags & ~XT_SCTP_VALID_FLAGS)
+ && !(info->invflags & ~info->flags)
+ && ((!(info->flags & XT_SCTP_CHUNK_TYPES)) ||
+ (info->chunk_match_type &
+ (SCTP_CHUNK_MATCH_ALL
+ | SCTP_CHUNK_MATCH_ANY
+ | SCTP_CHUNK_MATCH_ONLY)));
+}
+
+
+static struct xt_match sctp_match =
+{
+ .name = "sctp",
+ .match = &match,
+ .checkentry = &checkentry,
+ .me = THIS_MODULE
+};
+static struct xt_match sctp6_match =
+{
+ .name = "sctp",
+ .match = &match,
+ .checkentry = &checkentry6,
+ .me = THIS_MODULE
+};
+
+
+static int __init init(void)
+{
+ int ret;
+ ret = xt_register_match(AF_INET, &sctp_match);
+ if (ret)
+ return ret;
+
+ ret = xt_register_match(AF_INET6, &sctp6_match);
+ if (ret)
+ xt_unregister_match(AF_INET, &sctp_match);
+
+ return ret;
+}
+
+static void __exit fini(void)
+{
+ xt_unregister_match(AF_INET6, &sctp6_match);
+ xt_unregister_match(AF_INET, &sctp_match);
+}
+
+module_init(init);
+module_exit(fini);