em_text.c

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/*
 * net/sched/em_text.c  Textsearch ematch
 *
 *      This program is free software; you can redistribute it and/or
 *      modify it under the terms of the GNU General Public License
 *      as published by the Free Software Foundation; either version
 *      2 of the License, or (at your option) any later version.
 *
 * Authors: Thomas Graf <[email protected]>
 */

#include <linux/slab.h>
#include <linux/module.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/skbuff.h>
#include <linux/textsearch.h>
#include <linux/tc_ematch/tc_em_text.h>
#include <net/pkt_cls.h>

struct text_match {
    u16         from_offset;
    u16         to_offset;
    u8          from_layer;
    u8          to_layer;
    struct ts_config    *config;
};

#define EM_TEXT_PRIV(m) ((struct text_match *) (m)->data)

static int em_text_match(struct sk_buff *skb, struct tcf_ematch *m,
             struct tcf_pkt_info *info)
{
    struct text_match *tm = EM_TEXT_PRIV(m);
    int from, to;
    struct ts_state state;

    from = tcf_get_base_ptr(skb, tm->from_layer) - skb->data;
    from += tm->from_offset;

    to = tcf_get_base_ptr(skb, tm->to_layer) - skb->data;
    to += tm->to_offset;

    return skb_find_text(skb, from, to, tm->config, &state) != UINT_MAX;
}

static int em_text_change(struct tcf_proto *tp, void *data, int len,
              struct tcf_ematch *m)
{
    struct text_match *tm;
    struct tcf_em_text *conf = data;
    struct ts_config *ts_conf;
    int flags = 0;

    if (len < sizeof(*conf) || len < (sizeof(*conf) + conf->pattern_len))
        return -EINVAL;

    if (conf->from_layer > conf->to_layer)
        return -EINVAL;

    if (conf->from_layer == conf->to_layer &&
        conf->from_offset > conf->to_offset)
        return -EINVAL;

retry:
    ts_conf = textsearch_prepare(conf->algo, (u8 *) conf + sizeof(*conf),
                     conf->pattern_len, GFP_KERNEL, flags);

    if (flags & TS_AUTOLOAD)
        rtnl_lock();

    if (IS_ERR(ts_conf)) {
        if (PTR_ERR(ts_conf) == -ENOENT && !(flags & TS_AUTOLOAD)) {
            rtnl_unlock();
            flags |= TS_AUTOLOAD;
            goto retry;
        } else
            return PTR_ERR(ts_conf);
    } else if (flags & TS_AUTOLOAD) {
        textsearch_destroy(ts_conf);
        return -EAGAIN;
    }

    tm = kmalloc(sizeof(*tm), GFP_KERNEL);
    if (tm == NULL) {
        textsearch_destroy(ts_conf);
        return -ENOBUFS;
    }

    tm->from_offset = conf->from_offset;
    tm->to_offset   = conf->to_offset;
    tm->from_layer  = conf->from_layer;
    tm->to_layer    = conf->to_layer;
    tm->config      = ts_conf;

    m->datalen = sizeof(*tm);
    m->data = (unsigned long) tm;

    return 0;
}

static void em_text_destroy(struct tcf_proto *tp, struct tcf_ematch *m)
{
    if (EM_TEXT_PRIV(m) && EM_TEXT_PRIV(m)->config)
        textsearch_destroy(EM_TEXT_PRIV(m)->config);
}

static int em_text_dump(struct sk_buff *skb, struct tcf_ematch *m)
{
    struct text_match *tm = EM_TEXT_PRIV(m);
    struct tcf_em_text conf;

    strncpy(conf.algo, tm->config->ops->name, sizeof(conf.algo) - 1);
    conf.from_offset = tm->from_offset;
    conf.to_offset = tm->to_offset;
    conf.from_layer = tm->from_layer;
    conf.to_layer = tm->to_layer;
    conf.pattern_len = textsearch_get_pattern_len(tm->config);
    conf.pad = 0;

    if (nla_put_nohdr(skb, sizeof(conf), &conf) < 0)
        goto nla_put_failure;
    if (nla_append(skb, conf.pattern_len,
               textsearch_get_pattern(tm->config)) < 0)
        goto nla_put_failure;
    return 0;

nla_put_failure:
    return -1;
}

static struct tcf_ematch_ops em_text_ops = {
    .kind     = TCF_EM_TEXT,
    .change   = em_text_change,
    .match    = em_text_match,
    .destroy  = em_text_destroy,
    .dump     = em_text_dump,
    .owner    = THIS_MODULE,
    .link     = LIST_HEAD_INIT(em_text_ops.link)
};

static int __init init_em_text(void)
{
    return tcf_em_register(&em_text_ops);
}

static void __exit exit_em_text(void)
{
    tcf_em_unregister(&em_text_ops);
}

MODULE_LICENSE("GPL");

module_init(init_em_text);
module_exit(exit_em_text);

MODULE_ALIAS_TCF_EMATCH(TCF_EM_TEXT);