diff options
Diffstat (limited to 'net/netfilter/xt_dccp.c')
| -rw-r--r-- | net/netfilter/xt_dccp.c | 221 |
1 files changed, 221 insertions, 0 deletions
diff --git a/net/netfilter/xt_dccp.c b/net/netfilter/xt_dccp.c new file mode 100644 index 00000000000..779f42fc952 --- /dev/null +++ b/net/netfilter/xt_dccp.c @@ -0,0 +1,221 @@ +/* + * iptables module for DCCP protocol header matching + * + * (C) 2005 by Harald Welte <laforge@netfilter.org> + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + */ + +#include <linux/module.h> +#include <linux/skbuff.h> +#include <linux/spinlock.h> +#include <net/ip.h> +#include <linux/dccp.h> + +#include <linux/netfilter/x_tables.h> +#include <linux/netfilter/xt_dccp.h> + +#include <linux/netfilter_ipv4/ip_tables.h> +#include <linux/netfilter_ipv6/ip6_tables.h> + +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>"); +MODULE_DESCRIPTION("Match for DCCP protocol packets"); +MODULE_ALIAS("ipt_dccp"); + +#define DCCHECK(cond, option, flag, invflag) (!((flag) & (option)) \ + || (!!((invflag) & (option)) ^ (cond))) + +static unsigned char *dccp_optbuf; +static DEFINE_SPINLOCK(dccp_buflock); + +static inline int +dccp_find_option(u_int8_t option, + const struct sk_buff *skb, + unsigned int protoff, + const struct dccp_hdr *dh, + int *hotdrop) +{ + /* tcp.doff is only 4 bits, ie. max 15 * 4 bytes */ + unsigned char *op; + unsigned int optoff = __dccp_hdr_len(dh); + unsigned int optlen = dh->dccph_doff*4 - __dccp_hdr_len(dh); + unsigned int i; + + if (dh->dccph_doff * 4 < __dccp_hdr_len(dh)) { + *hotdrop = 1; + return 0; + } + + if (!optlen) + return 0; + + spin_lock_bh(&dccp_buflock); + op = skb_header_pointer(skb, protoff + optoff, optlen, dccp_optbuf); + if (op == NULL) { + /* If we don't have the whole header, drop packet. */ + spin_unlock_bh(&dccp_buflock); + *hotdrop = 1; + return 0; + } + + for (i = 0; i < optlen; ) { + if (op[i] == option) { + spin_unlock_bh(&dccp_buflock); + return 1; + } + + if (op[i] < 2) + i++; + else + i += op[i+1]?:1; + } + + spin_unlock_bh(&dccp_buflock); + return 0; +} + + +static inline int +match_types(const struct dccp_hdr *dh, u_int16_t typemask) +{ + return (typemask & (1 << dh->dccph_type)); +} + +static inline int +match_option(u_int8_t option, const struct sk_buff *skb, unsigned int protoff, + const struct dccp_hdr *dh, int *hotdrop) +{ + return dccp_find_option(option, skb, protoff, dh, hotdrop); +} + +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_dccp_info *info = + (const struct xt_dccp_info *)matchinfo; + struct dccp_hdr _dh, *dh; + + if (offset) + return 0; + + dh = skb_header_pointer(skb, protoff, sizeof(_dh), &_dh); + if (dh == NULL) { + *hotdrop = 1; + return 0; + } + + return DCCHECK(((ntohs(dh->dccph_sport) >= info->spts[0]) + && (ntohs(dh->dccph_sport) <= info->spts[1])), + XT_DCCP_SRC_PORTS, info->flags, info->invflags) + && DCCHECK(((ntohs(dh->dccph_dport) >= info->dpts[0]) + && (ntohs(dh->dccph_dport) <= info->dpts[1])), + XT_DCCP_DEST_PORTS, info->flags, info->invflags) + && DCCHECK(match_types(dh, info->typemask), + XT_DCCP_TYPE, info->flags, info->invflags) + && DCCHECK(match_option(info->option, skb, protoff, dh, + hotdrop), + XT_DCCP_OPTION, info->flags, info->invflags); +} + +static int +checkentry(const char *tablename, + const void *inf, + void *matchinfo, + unsigned int matchsize, + unsigned int hook_mask) +{ + const struct ipt_ip *ip = inf; + const struct xt_dccp_info *info; + + info = (const struct xt_dccp_info *)matchinfo; + + return ip->proto == IPPROTO_DCCP + && !(ip->invflags & XT_INV_PROTO) + && matchsize == XT_ALIGN(sizeof(struct xt_dccp_info)) + && !(info->flags & ~XT_DCCP_VALID_FLAGS) + && !(info->invflags & ~XT_DCCP_VALID_FLAGS) + && !(info->invflags & ~info->flags); +} + +static int +checkentry6(const char *tablename, + const void *inf, + void *matchinfo, + unsigned int matchsize, + unsigned int hook_mask) +{ + const struct ip6t_ip6 *ip = inf; + const struct xt_dccp_info *info; + + info = (const struct xt_dccp_info *)matchinfo; + + return ip->proto == IPPROTO_DCCP + && !(ip->invflags & XT_INV_PROTO) + && matchsize == XT_ALIGN(sizeof(struct xt_dccp_info)) + && !(info->flags & ~XT_DCCP_VALID_FLAGS) + && !(info->invflags & ~XT_DCCP_VALID_FLAGS) + && !(info->invflags & ~info->flags); +} + + +static struct xt_match dccp_match = +{ + .name = "dccp", + .match = &match, + .checkentry = &checkentry, + .me = THIS_MODULE, +}; +static struct xt_match dccp6_match = +{ + .name = "dccp", + .match = &match, + .checkentry = &checkentry6, + .me = THIS_MODULE, +}; + + +static int __init init(void) +{ + int ret; + + /* doff is 8 bits, so the maximum option size is (4*256). Don't put + * this in BSS since DaveM is worried about locked TLB's for kernel + * BSS. */ + dccp_optbuf = kmalloc(256 * 4, GFP_KERNEL); + if (!dccp_optbuf) + return -ENOMEM; + ret = xt_register_match(AF_INET, &dccp_match); + if (ret) + goto out_kfree; + ret = xt_register_match(AF_INET6, &dccp6_match); + if (ret) + goto out_unreg; + + return ret; + +out_unreg: + xt_unregister_match(AF_INET, &dccp_match); +out_kfree: + kfree(dccp_optbuf); + + return ret; +} + +static void __exit fini(void) +{ + xt_unregister_match(AF_INET6, &dccp6_match); + xt_unregister_match(AF_INET, &dccp_match); + kfree(dccp_optbuf); +} + +module_init(init); +module_exit(fini); |