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/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
  22 struct text_match
  23 {
  24         u16                     from_offset;
  25         u16                     to_offset;
  26         u8                      from_layer;
  27         u8                      to_layer;
  28         struct ts_config        *config;
  29 };
  30
  31 #define EM_TEXT_PRIV(m) ((struct text_match *) (m)->data)
  32
  33 static int em_text_match(struct sk_buff *skb, struct tcf_ematch *m,
  34                          struct tcf_pkt_info *info)
  35 {
  36         struct text_match *tm = EM_TEXT_PRIV(m);
  37         int from, to;
  38         struct ts_state state;
  39
  40         from = tcf_get_base_ptr(skb, tm->from_layer) - skb->data;
  41         from += tm->from_offset;
  42
  43         to = tcf_get_base_ptr(skb, tm->to_layer) - skb->data;
  44         to += tm->to_offset;
  45
  46         return skb_find_text(skb, from, to, tm->config, &state) != UINT_MAX;
  47 }
  48
  49 static int em_text_change(struct tcf_proto *tp, void *data, int len,
  50                           struct tcf_ematch *m)
  51 {
  52         struct text_match *tm;
  53         struct tcf_em_text *conf = data;
  54         struct ts_config *ts_conf;
  55         int flags = 0;
  56
  57         if (len < sizeof(*conf) || len < (sizeof(*conf) + conf->pattern_len))
  58                 return -EINVAL;
  59
  60         if (conf->from_layer > conf->to_layer)
  61                 return -EINVAL;
  62
  63         if (conf->from_layer == conf->to_layer &&
  64             conf->from_offset > conf->to_offset)
  65                 return -EINVAL;
  66
  67 retry:
  68         ts_conf = textsearch_prepare(conf->algo, (u8 *) conf + sizeof(*conf),
  69                                      conf->pattern_len, GFP_KERNEL, flags);
  70
  71         if (flags & TS_AUTOLOAD)
  72                 rtnl_lock();
  73
  74         if (IS_ERR(ts_conf)) {
  75                 if (PTR_ERR(ts_conf) == -ENOENT && !(flags & TS_AUTOLOAD)) {
  76                         rtnl_unlock();
  77                         flags |= TS_AUTOLOAD;
  78                         goto retry;
  79                 } else
  80                         return PTR_ERR(ts_conf);
  81         } else if (flags & TS_AUTOLOAD) {
  82                 textsearch_destroy(ts_conf);
  83                 return -EAGAIN;
  84         }
  85
  86         tm = kmalloc(sizeof(*tm), GFP_KERNEL);
  87         if (tm == NULL) {
  88                 textsearch_destroy(ts_conf);
  89                 return -ENOBUFS;
  90         }
  91
  92         tm->from_offset = conf->from_offset;
  93         tm->to_offset   = conf->to_offset;
  94         tm->from_layer  = conf->from_layer;
  95         tm->to_layer    = conf->to_layer;
  96         tm->config      = ts_conf;
  97
  98         m->datalen = sizeof(*tm);
  99         m->data = (unsigned long) tm;
 100
 101         return 0;
 102 }
 103
 104 static void em_text_destroy(struct tcf_proto *tp, struct tcf_ematch *m)
 105 {
 106         if (EM_TEXT_PRIV(m) && EM_TEXT_PRIV(m)->config)
 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         if (nla_put_nohdr(skb, sizeof(conf), &conf) < 0)
 124                 goto nla_put_failure;
 125         if (nla_append(skb, conf.pattern_len,
 126                        textsearch_get_pattern(tm->config)) < 0)
 127                 goto nla_put_failure;
 128         return 0;
 129
 130 nla_put_failure:
 131         return -1;
 132 }
 133
 134 static struct tcf_ematch_ops em_text_ops = {
 135         .kind     = TCF_EM_TEXT,
 136         .change   = em_text_change,
 137         .match    = em_text_match,
 138         .destroy  = em_text_destroy,
 139         .dump     = em_text_dump,
 140         .owner    = THIS_MODULE,
 141         .link     = LIST_HEAD_INIT(em_text_ops.link)
 142 };
 143
 144 static int __init init_em_text(void)
 145 {
 146         return tcf_em_register(&em_text_ops);
 147 }
 148
 149 static void __exit exit_em_text(void)
 150 {
 151         tcf_em_unregister(&em_text_ops);
 152 }
 153
 154 MODULE_LICENSE("GPL");
 155
 156 module_init(init_em_text);
 157 module_exit(exit_em_text);
 158
 159 MODULE_ALIAS_TCF_EMATCH(TCF_EM_TEXT);