cregit-Linux how code gets into the kernel

Release 4.11 net/netfilter/xt_dccp.c

Directory: net/netfilter
/*
 * 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/slab.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("Xtables: DCCP protocol packet match");
MODULE_ALIAS("ipt_dccp");
MODULE_ALIAS("ip6t_dccp");


#define DCCHECK(cond, option, flag, invflag) (!((flag) & (option)) \
                                  || (!!((invflag) & (option)) ^ (cond)))


static unsigned char *dccp_optbuf;
static DEFINE_SPINLOCK(dccp_buflock);


static inline bool dccp_find_option(u_int8_t option, const struct sk_buff *skb, unsigned int protoff, const struct dccp_hdr *dh, bool *hotdrop) { /* tcp.doff is only 4 bits, ie. max 15 * 4 bytes */ const 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)) goto invalid; if (!optlen) return false; 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. */ goto partial; } for (i = 0; i < optlen; ) { if (op[i] == option) { spin_unlock_bh(&dccp_buflock); return true; } if (op[i] < 2) i++; else i += op[i+1]?:1; } spin_unlock_bh(&dccp_buflock); return false; partial: spin_unlock_bh(&dccp_buflock); invalid: *hotdrop = true; return false; }

Contributors

PersonTokensPropCommitsCommitProp
Harald Welte17785.51%233.33%
Ilpo Järvinen2411.59%116.67%
Jan Engelhardt62.90%350.00%
Total207100.00%6100.00%


static inline bool match_types(const struct dccp_hdr *dh, u_int16_t typemask) { return typemask & (1 << dh->dccph_type); }

Contributors

PersonTokensPropCommitsCommitProp
Harald Welte2696.30%150.00%
Jan Engelhardt13.70%150.00%
Total27100.00%2100.00%


static inline bool match_option(u_int8_t option, const struct sk_buff *skb, unsigned int protoff, const struct dccp_hdr *dh, bool *hotdrop) { return dccp_find_option(option, skb, protoff, dh, hotdrop); }

Contributors

PersonTokensPropCommitsCommitProp
Harald Welte4295.45%250.00%
Jan Engelhardt24.55%250.00%
Total44100.00%4100.00%


static bool dccp_mt(const struct sk_buff *skb, struct xt_action_param *par) { const struct xt_dccp_info *info = par->matchinfo; const struct dccp_hdr *dh; struct dccp_hdr _dh; if (par->fragoff != 0) return false; dh = skb_header_pointer(skb, par->thoff, sizeof(_dh), &_dh); if (dh == NULL) { par->hotdrop = true; return false; } 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, par->thoff, dh, &par->hotdrop), XT_DCCP_OPTION, info->flags, info->invflags); }

Contributors

PersonTokensPropCommitsCommitProp
Harald Welte19286.49%222.22%
Jan Engelhardt3013.51%777.78%
Total222100.00%9100.00%


static int dccp_mt_check(const struct xt_mtchk_param *par) { const struct xt_dccp_info *info = par->matchinfo; if (info->flags & ~XT_DCCP_VALID_FLAGS) return -EINVAL; if (info->invflags & ~XT_DCCP_VALID_FLAGS) return -EINVAL; if (info->invflags & ~info->flags) return -EINVAL; return 0; }

Contributors

PersonTokensPropCommitsCommitProp
Harald Welte3451.52%222.22%
Jan Engelhardt2943.94%555.56%
Patrick McHardy34.55%222.22%
Total66100.00%9100.00%

static struct xt_match dccp_mt_reg[] __read_mostly = { { .name = "dccp", .family = NFPROTO_IPV4, .checkentry = dccp_mt_check, .match = dccp_mt, .matchsize = sizeof(struct xt_dccp_info), .proto = IPPROTO_DCCP, .me = THIS_MODULE, }, { .name = "dccp", .family = NFPROTO_IPV6, .checkentry = dccp_mt_check, .match = dccp_mt, .matchsize = sizeof(struct xt_dccp_info), .proto = IPPROTO_DCCP, .me = THIS_MODULE, }, };
static int __init dccp_mt_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_matches(dccp_mt_reg, ARRAY_SIZE(dccp_mt_reg)); if (ret) goto out_kfree; return ret; out_kfree: kfree(dccp_optbuf); return ret; }

Contributors

PersonTokensPropCommitsCommitProp
Harald Welte5787.69%250.00%
Patrick McHardy57.69%125.00%
Jan Engelhardt34.62%125.00%
Total65100.00%4100.00%


static void __exit dccp_mt_exit(void) { xt_unregister_matches(dccp_mt_reg, ARRAY_SIZE(dccp_mt_reg)); kfree(dccp_optbuf); }

Contributors

PersonTokensPropCommitsCommitProp
Harald Welte1770.83%250.00%
Patrick McHardy416.67%125.00%
Jan Engelhardt312.50%125.00%
Total24100.00%4100.00%

module_init(dccp_mt_init); module_exit(dccp_mt_exit);

Overall Contributors

PersonTokensPropCommitsCommitProp
Harald Welte65678.38%28.00%
Jan Engelhardt8910.63%1560.00%
Patrick McHardy617.29%416.00%
Ilpo Järvinen242.87%14.00%
Pablo Neira Ayuso30.36%14.00%
Tejun Heo30.36%14.00%
Hideaki Yoshifuji / 吉藤英明10.12%14.00%
Total837100.00%25100.00%
Directory: net/netfilter
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