/*
 *	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;
}

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;
}

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);
}

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

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");
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<div class='path'>path: <a href='/cgit.cgi/linux/net-next.git/log/?h=nds-private-remove&amp;id=b4cfe3971f6eab542dd7ecc398bfa1aeec889934'>root</a>/<a href='/cgit.cgi/linux/net-next.git/log/net?h=nds-private-remove&amp;id=b4cfe3971f6eab542dd7ecc398bfa1aeec889934'>net</a>/<a href='/cgit.cgi/linux/net-next.git/log/net/batman-adv?h=nds-private-remove&amp;id=b4cfe3971f6eab542dd7ecc398bfa1aeec889934'>batman-adv</a>/<a href='/cgit.cgi/linux/net-next.git/log/net/batman-adv/bat_iv_ogm.h?h=nds-private-remove&amp;id=b4cfe3971f6eab542dd7ecc398bfa1aeec889934'>bat_iv_ogm.h</a></div><div class='content'><table class='list nowrap'><tr class='nohover'><th class='left'>Age</th><th class='left'>Commit message (<a href='/cgit.cgi/linux/net-next.git/log/net/batman-adv/bat_iv_ogm.h?h=nds-private-remove&amp;id=b4cfe3971f6eab542dd7ecc398bfa1aeec889934&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th><th class='left'>Files</th><th class='left'>Lines</th></tr>
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<tr><th>author</th><td>Linus Torvalds &lt;torvalds@linux-foundation.org&gt;</td><td class='right'>2016-12-12 21:58:13 -0800</td></tr>
<tr><th>committer</th><td>Linus Torvalds &lt;torvalds@linux-foundation.org&gt;</td><td class='right'>2016-12-12 21:58:13 -0800</td></tr>
<tr><th>commit</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/commit/lib/locking-selftest-spin-hardirq.h?id=e7aa8c2eb11ba69b1b69099c3c7bd6be3087b0ba'>e7aa8c2eb11ba69b1b69099c3c7bd6be3087b0ba</a> (<a href='/cgit.cgi/linux/net-next.git/patch/lib/locking-selftest-spin-hardirq.h?id=e7aa8c2eb11ba69b1b69099c3c7bd6be3087b0ba'>patch</a>)</td></tr>
<tr><th>tree</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/tree/?id=e7aa8c2eb11ba69b1b69099c3c7bd6be3087b0ba'>f63906f41699c8e38af9d12b063e2ceab0286ef2</a> /<a href='/cgit.cgi/linux/net-next.git/tree/lib/locking-selftest-spin-hardirq.h?id=e7aa8c2eb11ba69b1b69099c3c7bd6be3087b0ba'>lib/locking-selftest-spin-hardirq.h</a></td></tr>
<tr><th>parent</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/commit/lib/locking-selftest-spin-hardirq.h?id=e34bac726d27056081d0250c0e173e4b155aa340'>e34bac726d27056081d0250c0e173e4b155aa340</a> (<a href='/cgit.cgi/linux/net-next.git/diff/lib/locking-selftest-spin-hardirq.h?id=e7aa8c2eb11ba69b1b69099c3c7bd6be3087b0ba&amp;id2=e34bac726d27056081d0250c0e173e4b155aa340'>diff</a>)</td></tr><tr><th>parent</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/commit/lib/locking-selftest-spin-hardirq.h?id=868c97a846a73e937d835b09b8c885a69df50ec8'>868c97a846a73e937d835b09b8c885a69df50ec8</a> (<a href='/cgit.cgi/linux/net-next.git/diff/lib/locking-selftest-spin-hardirq.h?id=e7aa8c2eb11ba69b1b69099c3c7bd6be3087b0ba&amp;id2=868c97a846a73e937d835b09b8c885a69df50ec8'>diff</a>)</td></tr></table>
<div class='commit-subject'>Merge tag 'docs-4.10' of git://git.lwn.net/linux<span class='decoration'><a class='deco' href='/cgit.cgi/linux/net-next.git/commit/lib/locking-selftest-spin-hardirq.h?id=e7aa8c2eb11ba69b1b69099c3c7bd6be3087b0ba'>HEAD</a><a class='branch-deco' href='/cgit.cgi/linux/net-next.git/log/lib/locking-selftest-spin-hardirq.h'>master</a></span></div><div class='commit-msg'>Pull documentation update from Jonathan Corbet:
 "These are the documentation changes for 4.10.

  It's another busy cycle for the docs tree, as the sphinx conversion
  continues. Highlights include:

   - Further work on PDF output, which remains a bit of a pain but
     should be more solid now.

   - Five more DocBook template files converted to Sphinx. Only 27 to
     go... Lots of plain-text files have also been converted and
     integrated.

   - Images in binary formats have been replaced with more
     source-friendly versions.

   - Various bits of organizational work, including the renaming of
     various files discussed at the kernel summit.

   - New documentation for the device_link mechanism.

  ... and, of course, lots of typo fixes and small updates"

* tag 'docs-4.10' of git://git.lwn.net/linux: (193 commits)
  dma-buf: Extract dma-buf.rst
  Update Documentation/00-INDEX
  docs: 00-INDEX: document directories/files with no docs
  docs: 00-INDEX: remove non-existing entries
  docs: 00-INDEX: add missing entries for documentation files/dirs
  docs: 00-INDEX: consolidate process/ and admin-guide/ description
  scripts: add a script to check if Documentation/00-INDEX is sane
  Docs: change sh -&gt; awk in REPORTING-BUGS
  Documentation/core-api/device_link: Add initial documentation
  core-api: remove an unexpected unident
  ppc/idle: Add documentation for powersave=off
  Doc: Correct typo, "Introdution" =&gt; "Introduction"
  Documentation/atomic_ops.txt: convert to ReST markup
  Documentation/local_ops.txt: convert to ReST markup
  Documentation/assoc_array.txt: convert to ReST markup
  docs-rst: parse-headers.pl: cleanup the documentation
  docs-rst: fix media cleandocs target
  docs-rst: media/Makefile: reorganize the rules
  docs-rst: media: build SVG from graphviz files
  docs-rst: replace bayer.png by a SVG image
  ...
</div><div class='diffstat-header'><a href='/cgit.cgi/linux/net-next.git/diff/?id=e7aa8c2eb11ba69b1b69099c3c7bd6be3087b0ba'>Diffstat</a> (limited to 'lib/locking-selftest-spin-hardirq.h')</div><table summary='diffstat' class='diffstat'>