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