cregit-Linux how code gets into the kernel

Release 4.11 net/netfilter/xt_u32.c

Directory: net/netfilter
/*
 *      xt_u32 - kernel module to match u32 packet content
 *
 *      Original author: Don Cohen <don@isis.cs3-inc.com>
 *      (C) CC Computer Consultants GmbH, 2007
 */

#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/spinlock.h>
#include <linux/skbuff.h>
#include <linux/types.h>
#include <linux/netfilter/x_tables.h>
#include <linux/netfilter/xt_u32.h>


static bool u32_match_it(const struct xt_u32 *data, const struct sk_buff *skb) { const struct xt_u32_test *ct; unsigned int testind; unsigned int nnums; unsigned int nvals; unsigned int i; __be32 n; u_int32_t pos; u_int32_t val; u_int32_t at; /* * Small example: "0 >> 28 == 4 && 8 & 0xFF0000 >> 16 = 6, 17" * (=IPv4 and (TCP or UDP)). Outer loop runs over the "&&" operands. */ for (testind = 0; testind < data->ntests; ++testind) { ct = &data->tests[testind]; at = 0; pos = ct->location[0].number; if (skb->len < 4 || pos > skb->len - 4) return false; if (skb_copy_bits(skb, pos, &n, sizeof(n)) < 0) BUG(); val = ntohl(n); nnums = ct->nnums; /* Inner loop runs over "&", "<<", ">>" and "@" operands */ for (i = 1; i < nnums; ++i) { u_int32_t number = ct->location[i].number; switch (ct->location[i].nextop) { case XT_U32_AND: val &= number; break; case XT_U32_LEFTSH: val <<= number; break; case XT_U32_RIGHTSH: val >>= number; break; case XT_U32_AT: if (at + val < at) return false; at += val; pos = number; if (at + 4 < at || skb->len < at + 4 || pos > skb->len - at - 4) return false; if (skb_copy_bits(skb, at + pos, &n, sizeof(n)) < 0) BUG(); val = ntohl(n); break; } } /* Run over the "," and ":" operands */ nvals = ct->nvalues; for (i = 0; i < nvals; ++i) if (ct->value[i].min <= val && val <= ct->value[i].max) break; if (i >= ct->nvalues) return false; } return true; }

Contributors

PersonTokensPropCommitsCommitProp
Jan Engelhardt33794.66%133.33%
Pavel Emelyanov102.81%133.33%
Al Viro92.53%133.33%
Total356100.00%3100.00%


static bool u32_mt(const struct sk_buff *skb, struct xt_action_param *par) { const struct xt_u32 *data = par->matchinfo; bool ret; ret = u32_match_it(data, skb); return ret ^ data->invert; }

Contributors

PersonTokensPropCommitsCommitProp
Jan Engelhardt46100.00%4100.00%
Total46100.00%4100.00%

static struct xt_match xt_u32_mt_reg __read_mostly = { .name = "u32", .revision = 0, .family = NFPROTO_UNSPEC, .match = u32_mt, .matchsize = sizeof(struct xt_u32), .me = THIS_MODULE, };
static int __init u32_mt_init(void) { return xt_register_match(&xt_u32_mt_reg); }

Contributors

PersonTokensPropCommitsCommitProp
Jan Engelhardt16100.00%3100.00%
Total16100.00%3100.00%


static void __exit u32_mt_exit(void) { xt_unregister_match(&xt_u32_mt_reg); }

Contributors

PersonTokensPropCommitsCommitProp
Jan Engelhardt15100.00%3100.00%
Total15100.00%3100.00%

module_init(u32_mt_init); module_exit(u32_mt_exit); MODULE_AUTHOR("Jan Engelhardt <jengelh@medozas.de>"); MODULE_DESCRIPTION("Xtables: arbitrary byte matching"); MODULE_LICENSE("GPL"); MODULE_ALIAS("ipt_u32"); MODULE_ALIAS("ip6t_u32");

Overall Contributors

PersonTokensPropCommitsCommitProp
Jan Engelhardt51296.24%770.00%
Pavel Emelyanov101.88%110.00%
Al Viro91.69%110.00%
Patrick McHardy10.19%110.00%
Total532100.00%10100.00%
Directory: net/netfilter
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