![Patrick McHardy](/assets/img/avatar_default.png)
Signed-off-by: Patrick McHardy <kaber@trash.net> Signed-off-by: David S. Miller <davem@davemloft.net>
223 lines
5.2 KiB
C
223 lines
5.2 KiB
C
#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 struct xt_match *match,
|
|
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,
|
|
const struct xt_match *match,
|
|
void *matchinfo,
|
|
unsigned int matchsize,
|
|
unsigned int hook_mask)
|
|
{
|
|
const struct xt_sctp_info *info = matchinfo;
|
|
|
|
return !(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,
|
|
.matchsize = sizeof(struct xt_sctp_info),
|
|
.proto = IPPROTO_SCTP,
|
|
.checkentry = checkentry,
|
|
.me = THIS_MODULE
|
|
};
|
|
|
|
static struct xt_match sctp6_match = {
|
|
.name = "sctp",
|
|
.match = match,
|
|
.matchsize = sizeof(struct xt_sctp_info),
|
|
.proto = IPPROTO_SCTP,
|
|
.checkentry = checkentry,
|
|
.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);
|