linux/net/sched/em_text.c
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   1/*
   2 * net/sched/em_text.c  Textsearch ematch
   3 *
   4 *              This program is free software; you can redistribute it and/or
   5 *              modify it under the terms of the GNU General Public License
   6 *              as published by the Free Software Foundation; either version
   7 *              2 of the License, or (at your option) any later version.
   8 *
   9 * Authors:     Thomas Graf <tgraf@suug.ch>
  10 */
  11
  12#include <linux/slab.h>
  13#include <linux/module.h>
  14#include <linux/types.h>
  15#include <linux/kernel.h>
  16#include <linux/string.h>
  17#include <linux/skbuff.h>
  18#include <linux/textsearch.h>
  19#include <linux/tc_ematch/tc_em_text.h>
  20#include <net/pkt_cls.h>
  21
  22struct text_match {
  23        u16                     from_offset;
  24        u16                     to_offset;
  25        u8                      from_layer;
  26        u8                      to_layer;
  27        struct ts_config        *config;
  28};
  29
  30#define EM_TEXT_PRIV(m) ((struct text_match *) (m)->data)
  31
  32static int em_text_match(struct sk_buff *skb, struct tcf_ematch *m,
  33                         struct tcf_pkt_info *info)
  34{
  35        struct text_match *tm = EM_TEXT_PRIV(m);
  36        int from, to;
  37        struct ts_state state;
  38
  39        from = tcf_get_base_ptr(skb, tm->from_layer) - skb->data;
  40        from += tm->from_offset;
  41
  42        to = tcf_get_base_ptr(skb, tm->to_layer) - skb->data;
  43        to += tm->to_offset;
  44
  45        return skb_find_text(skb, from, to, tm->config, &state) != UINT_MAX;
  46}
  47
  48static int em_text_change(struct tcf_proto *tp, void *data, int len,
  49                          struct tcf_ematch *m)
  50{
  51        struct text_match *tm;
  52        struct tcf_em_text *conf = data;
  53        struct ts_config *ts_conf;
  54        int flags = 0;
  55
  56        if (len < sizeof(*conf) || len < (sizeof(*conf) + conf->pattern_len))
  57                return -EINVAL;
  58
  59        if (conf->from_layer > conf->to_layer)
  60                return -EINVAL;
  61
  62        if (conf->from_layer == conf->to_layer &&
  63            conf->from_offset > conf->to_offset)
  64                return -EINVAL;
  65
  66retry:
  67        ts_conf = textsearch_prepare(conf->algo, (u8 *) conf + sizeof(*conf),
  68                                     conf->pattern_len, GFP_KERNEL, flags);
  69
  70        if (flags & TS_AUTOLOAD)
  71                rtnl_lock();
  72
  73        if (IS_ERR(ts_conf)) {
  74                if (PTR_ERR(ts_conf) == -ENOENT && !(flags & TS_AUTOLOAD)) {
  75                        rtnl_unlock();
  76                        flags |= TS_AUTOLOAD;
  77                        goto retry;
  78                } else
  79                        return PTR_ERR(ts_conf);
  80        } else if (flags & TS_AUTOLOAD) {
  81                textsearch_destroy(ts_conf);
  82                return -EAGAIN;
  83        }
  84
  85        tm = kmalloc(sizeof(*tm), GFP_KERNEL);
  86        if (tm == NULL) {
  87                textsearch_destroy(ts_conf);
  88                return -ENOBUFS;
  89        }
  90
  91        tm->from_offset = conf->from_offset;
  92        tm->to_offset   = conf->to_offset;
  93        tm->from_layer  = conf->from_layer;
  94        tm->to_layer    = conf->to_layer;
  95        tm->config      = ts_conf;
  96
  97        m->datalen = sizeof(*tm);
  98        m->data = (unsigned long) tm;
  99
 100        return 0;
 101}
 102
 103static void em_text_destroy(struct tcf_proto *tp, struct tcf_ematch *m)
 104{
 105        if (EM_TEXT_PRIV(m) && EM_TEXT_PRIV(m)->config)
 106                textsearch_destroy(EM_TEXT_PRIV(m)->config);
 107}
 108
 109static int em_text_dump(struct sk_buff *skb, struct tcf_ematch *m)
 110{
 111        struct text_match *tm = EM_TEXT_PRIV(m);
 112        struct tcf_em_text conf;
 113
 114        strncpy(conf.algo, tm->config->ops->name, sizeof(conf.algo) - 1);
 115        conf.from_offset = tm->from_offset;
 116        conf.to_offset = tm->to_offset;
 117        conf.from_layer = tm->from_layer;
 118        conf.to_layer = tm->to_layer;
 119        conf.pattern_len = textsearch_get_pattern_len(tm->config);
 120        conf.pad = 0;
 121
 122        if (nla_put_nohdr(skb, sizeof(conf), &conf) < 0)
 123                goto nla_put_failure;
 124        if (nla_append(skb, conf.pattern_len,
 125                       textsearch_get_pattern(tm->config)) < 0)
 126                goto nla_put_failure;
 127        return 0;
 128
 129nla_put_failure:
 130        return -1;
 131}
 132
 133static struct tcf_ematch_ops em_text_ops = {
 134        .kind     = TCF_EM_TEXT,
 135        .change   = em_text_change,
 136        .match    = em_text_match,
 137        .destroy  = em_text_destroy,
 138        .dump     = em_text_dump,
 139        .owner    = THIS_MODULE,
 140        .link     = LIST_HEAD_INIT(em_text_ops.link)
 141};
 142
 143static int __init init_em_text(void)
 144{
 145        return tcf_em_register(&em_text_ops);
 146}
 147
 148static void __exit exit_em_text(void)
 149{
 150        tcf_em_unregister(&em_text_ops);
 151}
 152
 153MODULE_LICENSE("GPL");
 154
 155module_init(init_em_text);
 156module_exit(exit_em_text);
 157
 158MODULE_ALIAS_TCF_EMATCH(TCF_EM_TEXT);
 159
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