net/sched/em_text.c

   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/module.h>
  13 #include <linux/types.h>
  14 #include <linux/kernel.h>
  15 #include <linux/string.h>
  16 #include <linux/skbuff.h>
  17 #include <linux/textsearch.h>
  18 #include <linux/tc_ematch/tc_em_text.h>
  19 #include <net/pkt_cls.h>
  20
  21 struct text_match
  22 {
  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
  32 static 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
  48 static 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
  66 retry:
  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
 103 static void em_text_destroy(struct tcf_proto *tp, struct tcf_ematch *m)
 104 {
 105         textsearch_destroy(EM_TEXT_PRIV(m)->config);
 106 }
 107
 108 static int em_text_dump(struct sk_buff *skb, struct tcf_ematch *m)
 109 {
 110         struct text_match *tm = EM_TEXT_PRIV(m);
 111         struct tcf_em_text conf;
 112
 113         strncpy(conf.algo, tm->config->ops->name, sizeof(conf.algo) - 1);
 114         conf.from_offset = tm->from_offset;
 115         conf.to_offset = tm->to_offset;
 116         conf.from_layer = tm->from_layer;
 117         conf.to_layer = tm->to_layer;
 118         conf.pattern_len = textsearch_get_pattern_len(tm->config);
 119         conf.pad = 0;
 120
 121         if (nla_put_nohdr(skb, sizeof(conf), &conf) < 0)
 122                 goto nla_put_failure;
 123         if (nla_append(skb, conf.pattern_len,
 124                        textsearch_get_pattern(tm->config)) < 0)
 125                 goto nla_put_failure;
 126         return 0;
 127
 128 nla_put_failure:
 129         return -1;
 130 }
 131
 132 static struct tcf_ematch_ops em_text_ops = {
 133         .kind     = TCF_EM_TEXT,
 134         .change   = em_text_change,
 135         .match    = em_text_match,
 136         .destroy  = em_text_destroy,
 137         .dump     = em_text_dump,
 138         .owner    = THIS_MODULE,
 139         .link     = LIST_HEAD_INIT(em_text_ops.link)
 140 };
 141
 142 static int __init init_em_text(void)
 143 {
 144         return tcf_em_register(&em_text_ops);
 145 }
 146
 147 static void __exit exit_em_text(void)
 148 {
 149         tcf_em_unregister(&em_text_ops);
 150 }
 151
 152 MODULE_LICENSE("GPL");
 153
 154 module_init(init_em_text);
 155 module_exit(exit_em_text);
 156
 157 MODULE_ALIAS_TCF_EMATCH(TCF_EM_TEXT);