b4ba26119b
Since xt_action_param is writable, let's use it. The pointer to 'bool hotdrop' always worried (8 bytes (64-bit) to write 1 byte!). Surprisingly results in a reduction in size: text data bss filename 5457066 692730 357892 vmlinux.o-prev 5456554 692730 357892 vmlinux.o Signed-off-by: Jan Engelhardt <jengelh@medozas.de>
166 lines
4.6 KiB
C
166 lines
4.6 KiB
C
/* Kernel module to match one of a list of TCP/UDP(-Lite)/SCTP/DCCP ports:
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ports are in the same place so we can treat them as equal. */
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/* (C) 1999-2001 Paul `Rusty' Russell
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* (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/module.h>
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#include <linux/types.h>
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#include <linux/udp.h>
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#include <linux/skbuff.h>
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#include <linux/in.h>
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#include <linux/netfilter/xt_multiport.h>
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#include <linux/netfilter/x_tables.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_LICENSE("GPL");
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MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>");
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MODULE_DESCRIPTION("Xtables: multiple port matching for TCP, UDP, UDP-Lite, SCTP and DCCP");
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MODULE_ALIAS("ipt_multiport");
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MODULE_ALIAS("ip6t_multiport");
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/* Returns 1 if the port is matched by the test, 0 otherwise. */
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static inline bool
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ports_match_v1(const struct xt_multiport_v1 *minfo,
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u_int16_t src, u_int16_t dst)
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{
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unsigned int i;
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u_int16_t s, e;
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for (i = 0; i < minfo->count; i++) {
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s = minfo->ports[i];
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if (minfo->pflags[i]) {
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/* range port matching */
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e = minfo->ports[++i];
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pr_debug("src or dst matches with %d-%d?\n", s, e);
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if (minfo->flags == XT_MULTIPORT_SOURCE
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&& src >= s && src <= e)
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return true ^ minfo->invert;
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if (minfo->flags == XT_MULTIPORT_DESTINATION
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&& dst >= s && dst <= e)
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return true ^ minfo->invert;
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if (minfo->flags == XT_MULTIPORT_EITHER
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&& ((dst >= s && dst <= e)
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|| (src >= s && src <= e)))
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return true ^ minfo->invert;
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} else {
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/* exact port matching */
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pr_debug("src or dst matches with %d?\n", s);
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if (minfo->flags == XT_MULTIPORT_SOURCE
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&& src == s)
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return true ^ minfo->invert;
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if (minfo->flags == XT_MULTIPORT_DESTINATION
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&& dst == s)
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return true ^ minfo->invert;
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if (minfo->flags == XT_MULTIPORT_EITHER
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&& (src == s || dst == s))
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return true ^ minfo->invert;
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}
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}
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return minfo->invert;
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}
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static bool
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multiport_mt(const struct sk_buff *skb, struct xt_action_param *par)
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{
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const __be16 *pptr;
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__be16 _ports[2];
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const struct xt_multiport_v1 *multiinfo = par->matchinfo;
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if (par->fragoff != 0)
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return false;
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pptr = skb_header_pointer(skb, par->thoff, sizeof(_ports), _ports);
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if (pptr == 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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*/
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pr_debug("Dropping evil offset=0 tinygram.\n");
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par->hotdrop = true;
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return false;
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}
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return ports_match_v1(multiinfo, ntohs(pptr[0]), ntohs(pptr[1]));
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}
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static inline bool
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check(u_int16_t proto,
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u_int8_t ip_invflags,
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u_int8_t match_flags,
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u_int8_t count)
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{
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/* Must specify supported protocol, no unknown flags or bad count */
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return (proto == IPPROTO_TCP || proto == IPPROTO_UDP
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|| proto == IPPROTO_UDPLITE
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|| proto == IPPROTO_SCTP || proto == IPPROTO_DCCP)
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&& !(ip_invflags & XT_INV_PROTO)
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&& (match_flags == XT_MULTIPORT_SOURCE
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|| match_flags == XT_MULTIPORT_DESTINATION
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|| match_flags == XT_MULTIPORT_EITHER)
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&& count <= XT_MULTI_PORTS;
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}
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static int multiport_mt_check(const struct xt_mtchk_param *par)
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{
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const struct ipt_ip *ip = par->entryinfo;
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const struct xt_multiport_v1 *multiinfo = par->matchinfo;
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return check(ip->proto, ip->invflags, multiinfo->flags,
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multiinfo->count) ? 0 : -EINVAL;
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}
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static int multiport_mt6_check(const struct xt_mtchk_param *par)
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{
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const struct ip6t_ip6 *ip = par->entryinfo;
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const struct xt_multiport_v1 *multiinfo = par->matchinfo;
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return check(ip->proto, ip->invflags, multiinfo->flags,
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multiinfo->count) ? 0 : -EINVAL;
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}
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static struct xt_match multiport_mt_reg[] __read_mostly = {
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{
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.name = "multiport",
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.family = NFPROTO_IPV4,
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.revision = 1,
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.checkentry = multiport_mt_check,
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.match = multiport_mt,
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.matchsize = sizeof(struct xt_multiport_v1),
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.me = THIS_MODULE,
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},
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{
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.name = "multiport",
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.family = NFPROTO_IPV6,
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.revision = 1,
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.checkentry = multiport_mt6_check,
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.match = multiport_mt,
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.matchsize = sizeof(struct xt_multiport_v1),
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.me = THIS_MODULE,
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},
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};
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static int __init multiport_mt_init(void)
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{
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return xt_register_matches(multiport_mt_reg,
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ARRAY_SIZE(multiport_mt_reg));
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}
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static void __exit multiport_mt_exit(void)
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{
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xt_unregister_matches(multiport_mt_reg, ARRAY_SIZE(multiport_mt_reg));
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}
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module_init(multiport_mt_init);
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module_exit(multiport_mt_exit);
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