act_pedit.c

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/*
 * net/sched/pedit.c    Generic packet editor
 *
 *      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: Jamal Hadi Salim (2002-4)
 */

#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/errno.h>
#include <linux/skbuff.h>
#include <linux/rtnetlink.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <net/netlink.h>
#include <net/pkt_sched.h>
#include <linux/tc_act/tc_pedit.h>
#include <net/tc_act/tc_pedit.h>

#define PEDIT_TAB_MASK  15
static struct tcf_common *tcf_pedit_ht[PEDIT_TAB_MASK + 1];
static u32 pedit_idx_gen;
static DEFINE_RWLOCK(pedit_lock);

static struct tcf_hashinfo pedit_hash_info = {
    .htab   =   tcf_pedit_ht,
    .hmask  =   PEDIT_TAB_MASK,
    .lock   =   &pedit_lock,
};

static const struct nla_policy pedit_policy[TCA_PEDIT_MAX + 1] = {
    [TCA_PEDIT_PARMS]   = { .len = sizeof(struct tc_pedit) },
};

static int tcf_pedit_init(struct nlattr *nla, struct nlattr *est,
              struct tc_action *a, int ovr, int bind)
{
    struct nlattr *tb[TCA_PEDIT_MAX + 1];
    struct tc_pedit *parm;
    int ret = 0, err;
    struct tcf_pedit *p;
    struct tcf_common *pc;
    struct tc_pedit_key *keys = NULL;
    int ksize;

    if (nla == NULL)
        return -EINVAL;

    err = nla_parse_nested(tb, TCA_PEDIT_MAX, nla, pedit_policy);
    if (err < 0)
        return err;

    if (tb[TCA_PEDIT_PARMS] == NULL)
        return -EINVAL;
    parm = nla_data(tb[TCA_PEDIT_PARMS]);
    ksize = parm->nkeys * sizeof(struct tc_pedit_key);
    if (nla_len(tb[TCA_PEDIT_PARMS]) < sizeof(*parm) + ksize)
        return -EINVAL;

    pc = tcf_hash_check(parm->index, a, bind, &pedit_hash_info);
    if (!pc) {
        if (!parm->nkeys)
            return -EINVAL;
        pc = tcf_hash_create(parm->index, est, a, sizeof(*p), bind,
                     &pedit_idx_gen, &pedit_hash_info);
        if (IS_ERR(pc))
            return PTR_ERR(pc);
        p = to_pedit(pc);
        keys = kmalloc(ksize, GFP_KERNEL);
        if (keys == NULL) {
            if (est)
                gen_kill_estimator(&pc->tcfc_bstats,
                           &pc->tcfc_rate_est);
            kfree_rcu(pc, tcfc_rcu);
            return -ENOMEM;
        }
        ret = ACT_P_CREATED;
    } else {
        p = to_pedit(pc);
        if (!ovr) {
            tcf_hash_release(pc, bind, &pedit_hash_info);
            return -EEXIST;
        }
        if (p->tcfp_nkeys && p->tcfp_nkeys != parm->nkeys) {
            keys = kmalloc(ksize, GFP_KERNEL);
            if (keys == NULL)
                return -ENOMEM;
        }
    }

    spin_lock_bh(&p->tcf_lock);
    p->tcfp_flags = parm->flags;
    p->tcf_action = parm->action;
    if (keys) {
        kfree(p->tcfp_keys);
        p->tcfp_keys = keys;
        p->tcfp_nkeys = parm->nkeys;
    }
    memcpy(p->tcfp_keys, parm->keys, ksize);
    spin_unlock_bh(&p->tcf_lock);
    if (ret == ACT_P_CREATED)
        tcf_hash_insert(pc, &pedit_hash_info);
    return ret;
}

static int tcf_pedit_cleanup(struct tc_action *a, int bind)
{
    struct tcf_pedit *p = a->priv;

    if (p) {
        struct tc_pedit_key *keys = p->tcfp_keys;
        if (tcf_hash_release(&p->common, bind, &pedit_hash_info)) {
            kfree(keys);
            return 1;
        }
    }
    return 0;
}

static int tcf_pedit(struct sk_buff *skb, const struct tc_action *a,
             struct tcf_result *res)
{
    struct tcf_pedit *p = a->priv;
    int i, munged = 0;
    unsigned int off;

    if (skb_cloned(skb) &&
        pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
        return p->tcf_action;

    off = skb_network_offset(skb);

    spin_lock(&p->tcf_lock);

    p->tcf_tm.lastuse = jiffies;

    if (p->tcfp_nkeys > 0) {
        struct tc_pedit_key *tkey = p->tcfp_keys;

        for (i = p->tcfp_nkeys; i > 0; i--, tkey++) {
            u32 *ptr, _data;
            int offset = tkey->off;

            if (tkey->offmask) {
                char *d, _d;

                d = skb_header_pointer(skb, off + tkey->at, 1,
                               &_d);
                if (!d)
                    goto bad;
                offset += (*d & tkey->offmask) >> tkey->shift;
            }

            if (offset % 4) {
                pr_info("tc filter pedit"
                    " offset must be on 32 bit boundaries\n");
                goto bad;
            }
            if (offset > 0 && offset > skb->len) {
                pr_info("tc filter pedit"
                    " offset %d can't exceed pkt length %d\n",
                       offset, skb->len);
                goto bad;
            }

            ptr = skb_header_pointer(skb, off + offset, 4, &_data);
            if (!ptr)
                goto bad;
            /* just do it, baby */
            *ptr = ((*ptr & tkey->mask) ^ tkey->val);
            if (ptr == &_data)
                skb_store_bits(skb, off + offset, ptr, 4);
            munged++;
        }

        if (munged)
            skb->tc_verd = SET_TC_MUNGED(skb->tc_verd);
        goto done;
    } else
        WARN(1, "pedit BUG: index %d\n", p->tcf_index);

bad:
    p->tcf_qstats.overlimits++;
done:
    bstats_update(&p->tcf_bstats, skb);
    spin_unlock(&p->tcf_lock);
    return p->tcf_action;
}

static int tcf_pedit_dump(struct sk_buff *skb, struct tc_action *a,
              int bind, int ref)
{
    unsigned char *b = skb_tail_pointer(skb);
    struct tcf_pedit *p = a->priv;
    struct tc_pedit *opt;
    struct tcf_t t;
    int s;

    s = sizeof(*opt) + p->tcfp_nkeys * sizeof(struct tc_pedit_key);

    /* netlink spinlocks held above us - must use ATOMIC */
    opt = kzalloc(s, GFP_ATOMIC);
    if (unlikely(!opt))
        return -ENOBUFS;

    memcpy(opt->keys, p->tcfp_keys,
           p->tcfp_nkeys * sizeof(struct tc_pedit_key));
    opt->index = p->tcf_index;
    opt->nkeys = p->tcfp_nkeys;
    opt->flags = p->tcfp_flags;
    opt->action = p->tcf_action;
    opt->refcnt = p->tcf_refcnt - ref;
    opt->bindcnt = p->tcf_bindcnt - bind;

    if (nla_put(skb, TCA_PEDIT_PARMS, s, opt))
        goto nla_put_failure;
    t.install = jiffies_to_clock_t(jiffies - p->tcf_tm.install);
    t.lastuse = jiffies_to_clock_t(jiffies - p->tcf_tm.lastuse);
    t.expires = jiffies_to_clock_t(p->tcf_tm.expires);
    if (nla_put(skb, TCA_PEDIT_TM, sizeof(t), &t))
        goto nla_put_failure;
    kfree(opt);
    return skb->len;

nla_put_failure:
    nlmsg_trim(skb, b);
    kfree(opt);
    return -1;
}

static struct tc_action_ops act_pedit_ops = {
    .kind       =   "pedit",
    .hinfo      =   &pedit_hash_info,
    .type       =   TCA_ACT_PEDIT,
    .capab      =   TCA_CAP_NONE,
    .owner      =   THIS_MODULE,
    .act        =   tcf_pedit,
    .dump       =   tcf_pedit_dump,
    .cleanup    =   tcf_pedit_cleanup,
    .lookup     =   tcf_hash_search,
    .init       =   tcf_pedit_init,
    .walk       =   tcf_generic_walker
};

MODULE_AUTHOR("Jamal Hadi Salim(2002-4)");
MODULE_DESCRIPTION("Generic Packet Editor actions");
MODULE_LICENSE("GPL");

static int __init pedit_init_module(void)
{
    return tcf_register_action(&act_pedit_ops);
}

static void __exit pedit_cleanup_module(void)
{
    tcf_unregister_action(&act_pedit_ops);
}

module_init(pedit_init_module);
module_exit(pedit_cleanup_module);