cls_api.c

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/*
 * net/sched/cls_api.c  Packet classifier API.
 *
 *      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: Alexey Kuznetsov, <[email protected]>
 *
 * Changes:
 *
 * Eduardo J. Blanco <[email protected]> :990222: kmod support
 *
 */

#include <linux/module.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/errno.h>
#include <linux/skbuff.h>
#include <linux/init.h>
#include <linux/kmod.h>
#include <linux/netlink.h>
#include <linux/err.h>
#include <linux/slab.h>
#include <net/net_namespace.h>
#include <net/sock.h>
#include <net/netlink.h>
#include <net/pkt_sched.h>
#include <net/pkt_cls.h>

/* The list of all installed classifier types */

static struct tcf_proto_ops *tcf_proto_base __read_mostly;

/* Protects list of registered TC modules. It is pure SMP lock. */
static DEFINE_RWLOCK(cls_mod_lock);

/* Find classifier type by string name */

static const struct tcf_proto_ops *tcf_proto_lookup_ops(struct nlattr *kind)
{
    const struct tcf_proto_ops *t = NULL;

    if (kind) {
        read_lock(&cls_mod_lock);
        for (t = tcf_proto_base; t; t = t->next) {
            if (nla_strcmp(kind, t->kind) == 0) {
                if (!try_module_get(t->owner))
                    t = NULL;
                break;
            }
        }
        read_unlock(&cls_mod_lock);
    }
    return t;
}

/* Register(unregister) new classifier type */

int register_tcf_proto_ops(struct tcf_proto_ops *ops)
{
    struct tcf_proto_ops *t, **tp;
    int rc = -EEXIST;

    write_lock(&cls_mod_lock);
    for (tp = &tcf_proto_base; (t = *tp) != NULL; tp = &t->next)
        if (!strcmp(ops->kind, t->kind))
            goto out;

    ops->next = NULL;
    *tp = ops;
    rc = 0;
out:
    write_unlock(&cls_mod_lock);
    return rc;
}
EXPORT_SYMBOL(register_tcf_proto_ops);

int unregister_tcf_proto_ops(struct tcf_proto_ops *ops)
{
    struct tcf_proto_ops *t, **tp;
    int rc = -ENOENT;

    write_lock(&cls_mod_lock);
    for (tp = &tcf_proto_base; (t = *tp) != NULL; tp = &t->next)
        if (t == ops)
            break;

    if (!t)
        goto out;
    *tp = t->next;
    rc = 0;
out:
    write_unlock(&cls_mod_lock);
    return rc;
}
EXPORT_SYMBOL(unregister_tcf_proto_ops);

static int tfilter_notify(struct net *net, struct sk_buff *oskb,
              struct nlmsghdr *n, struct tcf_proto *tp,
              unsigned long fh, int event);


/* Select new prio value from the range, managed by kernel. */

static inline u32 tcf_auto_prio(struct tcf_proto *tp)
{
    u32 first = TC_H_MAKE(0xC0000000U, 0U);

    if (tp)
        first = tp->prio - 1;

    return first;
}

/* Add/change/delete/get a filter node */

static int tc_ctl_tfilter(struct sk_buff *skb, struct nlmsghdr *n, void *arg)
{
    struct net *net = sock_net(skb->sk);
    struct nlattr *tca[TCA_MAX + 1];
    spinlock_t *root_lock;
    struct tcmsg *t;
    u32 protocol;
    u32 prio;
    u32 nprio;
    u32 parent;
    struct net_device *dev;
    struct Qdisc  *q;
    struct tcf_proto **back, **chain;
    struct tcf_proto *tp;
    const struct tcf_proto_ops *tp_ops;
    const struct Qdisc_class_ops *cops;
    unsigned long cl;
    unsigned long fh;
    int err;
    int tp_created = 0;

replay:
    t = nlmsg_data(n);
    protocol = TC_H_MIN(t->tcm_info);
    prio = TC_H_MAJ(t->tcm_info);
    nprio = prio;
    parent = t->tcm_parent;
    cl = 0;

    if (prio == 0) {
        /* If no priority is given, user wants we allocated it. */
        if (n->nlmsg_type != RTM_NEWTFILTER ||
            !(n->nlmsg_flags & NLM_F_CREATE))
            return -ENOENT;
        prio = TC_H_MAKE(0x80000000U, 0U);
    }

    /* Find head of filter chain. */

    /* Find link */
    dev = __dev_get_by_index(net, t->tcm_ifindex);
    if (dev == NULL)
        return -ENODEV;

    err = nlmsg_parse(n, sizeof(*t), tca, TCA_MAX, NULL);
    if (err < 0)
        return err;

    /* Find qdisc */
    if (!parent) {
        q = dev->qdisc;
        parent = q->handle;
    } else {
        q = qdisc_lookup(dev, TC_H_MAJ(t->tcm_parent));
        if (q == NULL)
            return -EINVAL;
    }

    /* Is it classful? */
    cops = q->ops->cl_ops;
    if (!cops)
        return -EINVAL;

    if (cops->tcf_chain == NULL)
        return -EOPNOTSUPP;

    /* Do we search for filter, attached to class? */
    if (TC_H_MIN(parent)) {
        cl = cops->get(q, parent);
        if (cl == 0)
            return -ENOENT;
    }

    /* And the last stroke */
    chain = cops->tcf_chain(q, cl);
    err = -EINVAL;
    if (chain == NULL)
        goto errout;

    /* Check the chain for existence of proto-tcf with this priority */
    for (back = chain; (tp = *back) != NULL; back = &tp->next) {
        if (tp->prio >= prio) {
            if (tp->prio == prio) {
                if (!nprio ||
                    (tp->protocol != protocol && protocol))
                    goto errout;
            } else
                tp = NULL;
            break;
        }
    }

    root_lock = qdisc_root_sleeping_lock(q);

    if (tp == NULL) {
        /* Proto-tcf does not exist, create new one */

        if (tca[TCA_KIND] == NULL || !protocol)
            goto errout;

        err = -ENOENT;
        if (n->nlmsg_type != RTM_NEWTFILTER ||
            !(n->nlmsg_flags & NLM_F_CREATE))
            goto errout;


        /* Create new proto tcf */

        err = -ENOBUFS;
        tp = kzalloc(sizeof(*tp), GFP_KERNEL);
        if (tp == NULL)
            goto errout;
        err = -ENOENT;
        tp_ops = tcf_proto_lookup_ops(tca[TCA_KIND]);
        if (tp_ops == NULL) {
#ifdef CONFIG_MODULES
            struct nlattr *kind = tca[TCA_KIND];
            char name[IFNAMSIZ];

            if (kind != NULL &&
                nla_strlcpy(name, kind, IFNAMSIZ) < IFNAMSIZ) {
                rtnl_unlock();
                request_module("cls_%s", name);
                rtnl_lock();
                tp_ops = tcf_proto_lookup_ops(kind);
                /* We dropped the RTNL semaphore in order to
                 * perform the module load.  So, even if we
                 * succeeded in loading the module we have to
                 * replay the request.  We indicate this using
                 * -EAGAIN.
                 */
                if (tp_ops != NULL) {
                    module_put(tp_ops->owner);
                    err = -EAGAIN;
                }
            }
#endif
            kfree(tp);
            goto errout;
        }
        tp->ops = tp_ops;
        tp->protocol = protocol;
        tp->prio = nprio ? : TC_H_MAJ(tcf_auto_prio(*back));
        tp->q = q;
        tp->classify = tp_ops->classify;
        tp->classid = parent;

        err = tp_ops->init(tp);
        if (err != 0) {
            module_put(tp_ops->owner);
            kfree(tp);
            goto errout;
        }

        tp_created = 1;

    } else if (tca[TCA_KIND] && nla_strcmp(tca[TCA_KIND], tp->ops->kind))
        goto errout;

    fh = tp->ops->get(tp, t->tcm_handle);

    if (fh == 0) {
        if (n->nlmsg_type == RTM_DELTFILTER && t->tcm_handle == 0) {
            spin_lock_bh(root_lock);
            *back = tp->next;
            spin_unlock_bh(root_lock);

            tfilter_notify(net, skb, n, tp, fh, RTM_DELTFILTER);
            tcf_destroy(tp);
            err = 0;
            goto errout;
        }

        err = -ENOENT;
        if (n->nlmsg_type != RTM_NEWTFILTER ||
            !(n->nlmsg_flags & NLM_F_CREATE))
            goto errout;
    } else {
        switch (n->nlmsg_type) {
        case RTM_NEWTFILTER:
            err = -EEXIST;
            if (n->nlmsg_flags & NLM_F_EXCL) {
                if (tp_created)
                    tcf_destroy(tp);
                goto errout;
            }
            break;
        case RTM_DELTFILTER:
            err = tp->ops->delete(tp, fh);
            if (err == 0)
                tfilter_notify(net, skb, n, tp, fh, RTM_DELTFILTER);
            goto errout;
        case RTM_GETTFILTER:
            err = tfilter_notify(net, skb, n, tp, fh, RTM_NEWTFILTER);
            goto errout;
        default:
            err = -EINVAL;
            goto errout;
        }
    }

    err = tp->ops->change(skb, tp, cl, t->tcm_handle, tca, &fh);
    if (err == 0) {
        if (tp_created) {
            spin_lock_bh(root_lock);
            tp->next = *back;
            *back = tp;
            spin_unlock_bh(root_lock);
        }
        tfilter_notify(net, skb, n, tp, fh, RTM_NEWTFILTER);
    } else {
        if (tp_created)
            tcf_destroy(tp);
    }

errout:
    if (cl)
        cops->put(q, cl);
    if (err == -EAGAIN)
        /* Replay the request. */
        goto replay;
    return err;
}

static int tcf_fill_node(struct sk_buff *skb, struct tcf_proto *tp,
             unsigned long fh, u32 portid, u32 seq, u16 flags, int event)
{
    struct tcmsg *tcm;
    struct nlmsghdr  *nlh;
    unsigned char *b = skb_tail_pointer(skb);

    nlh = nlmsg_put(skb, portid, seq, event, sizeof(*tcm), flags);
    if (!nlh)
        goto out_nlmsg_trim;
    tcm = nlmsg_data(nlh);
    tcm->tcm_family = AF_UNSPEC;
    tcm->tcm__pad1 = 0;
    tcm->tcm__pad2 = 0;
    tcm->tcm_ifindex = qdisc_dev(tp->q)->ifindex;
    tcm->tcm_parent = tp->classid;
    tcm->tcm_info = TC_H_MAKE(tp->prio, tp->protocol);
    if (nla_put_string(skb, TCA_KIND, tp->ops->kind))
        goto nla_put_failure;
    tcm->tcm_handle = fh;
    if (RTM_DELTFILTER != event) {
        tcm->tcm_handle = 0;
        if (tp->ops->dump && tp->ops->dump(tp, fh, skb, tcm) < 0)
            goto nla_put_failure;
    }
    nlh->nlmsg_len = skb_tail_pointer(skb) - b;
    return skb->len;

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

static int tfilter_notify(struct net *net, struct sk_buff *oskb,
              struct nlmsghdr *n, struct tcf_proto *tp,
              unsigned long fh, int event)
{
    struct sk_buff *skb;
    u32 portid = oskb ? NETLINK_CB(oskb).portid : 0;

    skb = alloc_skb(NLMSG_GOODSIZE, GFP_KERNEL);
    if (!skb)
        return -ENOBUFS;

    if (tcf_fill_node(skb, tp, fh, portid, n->nlmsg_seq, 0, event) <= 0) {
        kfree_skb(skb);
        return -EINVAL;
    }

    return rtnetlink_send(skb, net, portid, RTNLGRP_TC,
                  n->nlmsg_flags & NLM_F_ECHO);
}

struct tcf_dump_args {
    struct tcf_walker w;
    struct sk_buff *skb;
    struct netlink_callback *cb;
};

static int tcf_node_dump(struct tcf_proto *tp, unsigned long n,
             struct tcf_walker *arg)
{
    struct tcf_dump_args *a = (void *)arg;

    return tcf_fill_node(a->skb, tp, n, NETLINK_CB(a->cb->skb).portid,
                 a->cb->nlh->nlmsg_seq, NLM_F_MULTI, RTM_NEWTFILTER);
}

/* called with RTNL */
static int tc_dump_tfilter(struct sk_buff *skb, struct netlink_callback *cb)
{
    struct net *net = sock_net(skb->sk);
    int t;
    int s_t;
    struct net_device *dev;
    struct Qdisc *q;
    struct tcf_proto *tp, **chain;
    struct tcmsg *tcm = nlmsg_data(cb->nlh);
    unsigned long cl = 0;
    const struct Qdisc_class_ops *cops;
    struct tcf_dump_args arg;

    if (cb->nlh->nlmsg_len < NLMSG_LENGTH(sizeof(*tcm)))
        return skb->len;
    dev = __dev_get_by_index(net, tcm->tcm_ifindex);
    if (!dev)
        return skb->len;

    if (!tcm->tcm_parent)
        q = dev->qdisc;
    else
        q = qdisc_lookup(dev, TC_H_MAJ(tcm->tcm_parent));
    if (!q)
        goto out;
    cops = q->ops->cl_ops;
    if (!cops)
        goto errout;
    if (cops->tcf_chain == NULL)
        goto errout;
    if (TC_H_MIN(tcm->tcm_parent)) {
        cl = cops->get(q, tcm->tcm_parent);
        if (cl == 0)
            goto errout;
    }
    chain = cops->tcf_chain(q, cl);
    if (chain == NULL)
        goto errout;

    s_t = cb->args[0];

    for (tp = *chain, t = 0; tp; tp = tp->next, t++) {
        if (t < s_t)
            continue;
        if (TC_H_MAJ(tcm->tcm_info) &&
            TC_H_MAJ(tcm->tcm_info) != tp->prio)
            continue;
        if (TC_H_MIN(tcm->tcm_info) &&
            TC_H_MIN(tcm->tcm_info) != tp->protocol)
            continue;
        if (t > s_t)
            memset(&cb->args[1], 0, sizeof(cb->args)-sizeof(cb->args[0]));
        if (cb->args[1] == 0) {
            if (tcf_fill_node(skb, tp, 0, NETLINK_CB(cb->skb).portid,
                      cb->nlh->nlmsg_seq, NLM_F_MULTI,
                      RTM_NEWTFILTER) <= 0)
                break;

            cb->args[1] = 1;
        }
        if (tp->ops->walk == NULL)
            continue;
        arg.w.fn = tcf_node_dump;
        arg.skb = skb;
        arg.cb = cb;
        arg.w.stop = 0;
        arg.w.skip = cb->args[1] - 1;
        arg.w.count = 0;
        tp->ops->walk(tp, &arg.w);
        cb->args[1] = arg.w.count + 1;
        if (arg.w.stop)
            break;
    }

    cb->args[0] = t;

errout:
    if (cl)
        cops->put(q, cl);
out:
    return skb->len;
}

void tcf_exts_destroy(struct tcf_proto *tp, struct tcf_exts *exts)
{
#ifdef CONFIG_NET_CLS_ACT
    if (exts->action) {
        tcf_action_destroy(exts->action, TCA_ACT_UNBIND);
        exts->action = NULL;
    }
#endif
}
EXPORT_SYMBOL(tcf_exts_destroy);

int tcf_exts_validate(struct tcf_proto *tp, struct nlattr **tb,
          struct nlattr *rate_tlv, struct tcf_exts *exts,
          const struct tcf_ext_map *map)
{
    memset(exts, 0, sizeof(*exts));

#ifdef CONFIG_NET_CLS_ACT
    {
        struct tc_action *act;

        if (map->police && tb[map->police]) {
            act = tcf_action_init_1(tb[map->police], rate_tlv,
                        "police", TCA_ACT_NOREPLACE,
                        TCA_ACT_BIND);
            if (IS_ERR(act))
                return PTR_ERR(act);

            act->type = TCA_OLD_COMPAT;
            exts->action = act;
        } else if (map->action && tb[map->action]) {
            act = tcf_action_init(tb[map->action], rate_tlv, NULL,
                          TCA_ACT_NOREPLACE, TCA_ACT_BIND);
            if (IS_ERR(act))
                return PTR_ERR(act);

            exts->action = act;
        }
    }
#else
    if ((map->action && tb[map->action]) ||
        (map->police && tb[map->police]))
        return -EOPNOTSUPP;
#endif

    return 0;
}
EXPORT_SYMBOL(tcf_exts_validate);

void tcf_exts_change(struct tcf_proto *tp, struct tcf_exts *dst,
             struct tcf_exts *src)
{
#ifdef CONFIG_NET_CLS_ACT
    if (src->action) {
        struct tc_action *act;
        tcf_tree_lock(tp);
        act = dst->action;
        dst->action = src->action;
        tcf_tree_unlock(tp);
        if (act)
            tcf_action_destroy(act, TCA_ACT_UNBIND);
    }
#endif
}
EXPORT_SYMBOL(tcf_exts_change);

int tcf_exts_dump(struct sk_buff *skb, struct tcf_exts *exts,
          const struct tcf_ext_map *map)
{
#ifdef CONFIG_NET_CLS_ACT
    if (map->action && exts->action) {
        /*
         * again for backward compatible mode - we want
         * to work with both old and new modes of entering
         * tc data even if iproute2  was newer - jhs
         */
        struct nlattr *nest;

        if (exts->action->type != TCA_OLD_COMPAT) {
            nest = nla_nest_start(skb, map->action);
            if (nest == NULL)
                goto nla_put_failure;
            if (tcf_action_dump(skb, exts->action, 0, 0) < 0)
                goto nla_put_failure;
            nla_nest_end(skb, nest);
        } else if (map->police) {
            nest = nla_nest_start(skb, map->police);
            if (nest == NULL)
                goto nla_put_failure;
            if (tcf_action_dump_old(skb, exts->action, 0, 0) < 0)
                goto nla_put_failure;
            nla_nest_end(skb, nest);
        }
    }
#endif
    return 0;
nla_put_failure: __attribute__ ((unused))
    return -1;
}
EXPORT_SYMBOL(tcf_exts_dump);


int tcf_exts_dump_stats(struct sk_buff *skb, struct tcf_exts *exts,
            const struct tcf_ext_map *map)
{
#ifdef CONFIG_NET_CLS_ACT
    if (exts->action)
        if (tcf_action_copy_stats(skb, exts->action, 1) < 0)
            goto nla_put_failure;
#endif
    return 0;
nla_put_failure: __attribute__ ((unused))
    return -1;
}
EXPORT_SYMBOL(tcf_exts_dump_stats);

static int __init tc_filter_init(void)
{
    rtnl_register(PF_UNSPEC, RTM_NEWTFILTER, tc_ctl_tfilter, NULL, NULL);
    rtnl_register(PF_UNSPEC, RTM_DELTFILTER, tc_ctl_tfilter, NULL, NULL);
    rtnl_register(PF_UNSPEC, RTM_GETTFILTER, tc_ctl_tfilter,
              tc_dump_tfilter, NULL);

    return 0;
}

subsys_initcall(tc_filter_init);