text: /*
   * test/set flag bits stored in conntrack extension area.
   *
   * (C) 2013 Astaro GmbH & Co KG
   *
   * 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/ctype.h>
  #include <linux/export.h>
  #include <linux/jhash.h>
  #include <linux/spinlock.h>
  #include <linux/types.h>
  #include <linux/slab.h>
  
  #include <net/netfilter/nf_conntrack_ecache.h>
  #include <net/netfilter/nf_conntrack_labels.h>
  
  static unsigned int label_bits(const struct nf_conn_labels *l)
  {
  	unsigned int longs = l->words;
  	return longs * BITS_PER_LONG;
  }
  
  bool nf_connlabel_match(const struct nf_conn *ct, u16 bit)
  {
  	struct nf_conn_labels *labels = nf_ct_labels_find(ct);
  
  	if (!labels)
  		return false;
  
  	return bit < label_bits(labels) && test_bit(bit, labels->bits);
  }
  EXPORT_SYMBOL_GPL(nf_connlabel_match);
  
  int nf_connlabel_set(struct nf_conn *ct, u16 bit)
  {
  	struct nf_conn_labels *labels = nf_ct_labels_find(ct);
  
  	if (!labels || bit >= label_bits(labels))
  		return -ENOSPC;
  
  	if (test_bit(bit, labels->bits))
  		return 0;
  
  	if (!test_and_set_bit(bit, labels->bits))
  		nf_conntrack_event_cache(IPCT_LABEL, ct);
  
  	return 0;
  }
  EXPORT_SYMBOL_GPL(nf_connlabel_set);
  
  #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
  static void replace_u32(u32 *address, u32 mask, u32 new)
  {
  	u32 old, tmp;
  
  	do {
  		old = *address;
  		tmp = (old & mask) ^ new;
  	} while (cmpxchg(address, old, tmp) != old);
  }
  
  int nf_connlabels_replace(struct nf_conn *ct,
  			  const u32 *data,
  			  const u32 *mask, unsigned int words32)
  {
  	struct nf_conn_labels *labels;
  	unsigned int size, i;
  	u32 *dst;
  
  	labels = nf_ct_labels_find(ct);
  	if (!labels)
  		return -ENOSPC;
  
  	size = labels->words * sizeof(long);
  	if (size < (words32 * sizeof(u32)))
  		words32 = size / sizeof(u32);
  
  	dst = (u32 *) labels->bits;
  	if (words32) {
  		for (i = 0; i < words32; i++)
  			replace_u32(&dst[i], mask ? ~mask[i] : 0, data[i]);
  	}
  
  	size /= sizeof(u32);
  	for (i = words32; i < size; i++) /* pad */
  		replace_u32(&dst[i], 0, 0);
  
  	nf_conntrack_event_cache(IPCT_LABEL, ct);
  	return 0;
  }
  EXPORT_SYMBOL_GPL(nf_connlabels_replace);
  #endif
  
  static struct nf_ct_ext_type labels_extend __read_mostly = {
  	.len    = sizeof(struct nf_conn_labels),
  	.align  = __alignof__(struct nf_conn_labels),
  	.id     = NF_CT_EXT_LABELS,
  };
  
  int nf_conntrack_labels_init(void)
  {
  	return nf_ct_extend_register(&labels_extend);
  }
  
  void nf_conntrack_labels_fini(void)
  {
  	nf_ct_extend_unregister(&labels_extend);
  }
  