cls_route.c

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/*
 * net/sched/cls_route.c    ROUTE4 classifier.
 *
 *      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]>
 */

#include <linux/module.h>
#include <linux/slab.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/errno.h>
#include <linux/skbuff.h>
#include <net/dst.h>
#include <net/route.h>
#include <net/netlink.h>
#include <net/act_api.h>
#include <net/pkt_cls.h>

/*
 * 1. For now we assume that route tags < 256.
 *    It allows to use direct table lookups, instead of hash tables.
 * 2. For now we assume that "from TAG" and "fromdev DEV" statements
 *    are mutually  exclusive.
 * 3. "to TAG from ANY" has higher priority, than "to ANY from XXX"
 */

struct route4_fastmap {
    struct route4_filter    *filter;
    u32         id;
    int         iif;
};

struct route4_head {
    struct route4_fastmap   fastmap[16];
    struct route4_bucket    *table[256 + 1];
};

struct route4_bucket {
    /* 16 FROM buckets + 16 IIF buckets + 1 wildcard bucket */
    struct route4_filter    *ht[16 + 16 + 1];
};

struct route4_filter {
    struct route4_filter    *next;
    u32         id;
    int         iif;

    struct tcf_result   res;
    struct tcf_exts     exts;
    u32         handle;
    struct route4_bucket    *bkt;
};

#define ROUTE4_FAILURE ((struct route4_filter *)(-1L))

static const struct tcf_ext_map route_ext_map = {
    .police = TCA_ROUTE4_POLICE,
    .action = TCA_ROUTE4_ACT
};

static inline int route4_fastmap_hash(u32 id, int iif)
{
    return id & 0xF;
}

static void
route4_reset_fastmap(struct Qdisc *q, struct route4_head *head, u32 id)
{
    spinlock_t *root_lock = qdisc_root_sleeping_lock(q);

    spin_lock_bh(root_lock);
    memset(head->fastmap, 0, sizeof(head->fastmap));
    spin_unlock_bh(root_lock);
}

static void
route4_set_fastmap(struct route4_head *head, u32 id, int iif,
           struct route4_filter *f)
{
    int h = route4_fastmap_hash(id, iif);

    head->fastmap[h].id = id;
    head->fastmap[h].iif = iif;
    head->fastmap[h].filter = f;
}

static inline int route4_hash_to(u32 id)
{
    return id & 0xFF;
}

static inline int route4_hash_from(u32 id)
{
    return (id >> 16) & 0xF;
}

static inline int route4_hash_iif(int iif)
{
    return 16 + ((iif >> 16) & 0xF);
}

static inline int route4_hash_wild(void)
{
    return 32;
}

#define ROUTE4_APPLY_RESULT()                   \
{                               \
    *res = f->res;                      \
    if (tcf_exts_is_available(&f->exts)) {          \
        int r = tcf_exts_exec(skb, &f->exts, res);  \
        if (r < 0) {                    \
            dont_cache = 1;             \
            continue;               \
        }                       \
        return r;                   \
    } else if (!dont_cache)                 \
        route4_set_fastmap(head, id, iif, f);       \
    return 0;                       \
}

static int route4_classify(struct sk_buff *skb, const struct tcf_proto *tp,
               struct tcf_result *res)
{
    struct route4_head *head = (struct route4_head *)tp->root;
    struct dst_entry *dst;
    struct route4_bucket *b;
    struct route4_filter *f;
    u32 id, h;
    int iif, dont_cache = 0;

    dst = skb_dst(skb);
    if (!dst)
        goto failure;

    id = dst->tclassid;
    if (head == NULL)
        goto old_method;

    iif = inet_iif(skb);

    h = route4_fastmap_hash(id, iif);
    if (id == head->fastmap[h].id &&
        iif == head->fastmap[h].iif &&
        (f = head->fastmap[h].filter) != NULL) {
        if (f == ROUTE4_FAILURE)
            goto failure;

        *res = f->res;
        return 0;
    }

    h = route4_hash_to(id);

restart:
    b = head->table[h];
    if (b) {
        for (f = b->ht[route4_hash_from(id)]; f; f = f->next)
            if (f->id == id)
                ROUTE4_APPLY_RESULT();

        for (f = b->ht[route4_hash_iif(iif)]; f; f = f->next)
            if (f->iif == iif)
                ROUTE4_APPLY_RESULT();

        for (f = b->ht[route4_hash_wild()]; f; f = f->next)
            ROUTE4_APPLY_RESULT();

    }
    if (h < 256) {
        h = 256;
        id &= ~0xFFFF;
        goto restart;
    }

    if (!dont_cache)
        route4_set_fastmap(head, id, iif, ROUTE4_FAILURE);
failure:
    return -1;

old_method:
    if (id && (TC_H_MAJ(id) == 0 ||
           !(TC_H_MAJ(id^tp->q->handle)))) {
        res->classid = id;
        res->class = 0;
        return 0;
    }
    return -1;
}

static inline u32 to_hash(u32 id)
{
    u32 h = id & 0xFF;

    if (id & 0x8000)
        h += 256;
    return h;
}

static inline u32 from_hash(u32 id)
{
    id &= 0xFFFF;
    if (id == 0xFFFF)
        return 32;
    if (!(id & 0x8000)) {
        if (id > 255)
            return 256;
        return id & 0xF;
    }
    return 16 + (id & 0xF);
}

static unsigned long route4_get(struct tcf_proto *tp, u32 handle)
{
    struct route4_head *head = (struct route4_head *)tp->root;
    struct route4_bucket *b;
    struct route4_filter *f;
    unsigned int h1, h2;

    if (!head)
        return 0;

    h1 = to_hash(handle);
    if (h1 > 256)
        return 0;

    h2 = from_hash(handle >> 16);
    if (h2 > 32)
        return 0;

    b = head->table[h1];
    if (b) {
        for (f = b->ht[h2]; f; f = f->next)
            if (f->handle == handle)
                return (unsigned long)f;
    }
    return 0;
}

static void route4_put(struct tcf_proto *tp, unsigned long f)
{
}

static int route4_init(struct tcf_proto *tp)
{
    return 0;
}

static void
route4_delete_filter(struct tcf_proto *tp, struct route4_filter *f)
{
    tcf_unbind_filter(tp, &f->res);
    tcf_exts_destroy(tp, &f->exts);
    kfree(f);
}

static void route4_destroy(struct tcf_proto *tp)
{
    struct route4_head *head = tp->root;
    int h1, h2;

    if (head == NULL)
        return;

    for (h1 = 0; h1 <= 256; h1++) {
        struct route4_bucket *b;

        b = head->table[h1];
        if (b) {
            for (h2 = 0; h2 <= 32; h2++) {
                struct route4_filter *f;

                while ((f = b->ht[h2]) != NULL) {
                    b->ht[h2] = f->next;
                    route4_delete_filter(tp, f);
                }
            }
            kfree(b);
        }
    }
    kfree(head);
}

static int route4_delete(struct tcf_proto *tp, unsigned long arg)
{
    struct route4_head *head = (struct route4_head *)tp->root;
    struct route4_filter **fp, *f = (struct route4_filter *)arg;
    unsigned int h = 0;
    struct route4_bucket *b;
    int i;

    if (!head || !f)
        return -EINVAL;

    h = f->handle;
    b = f->bkt;

    for (fp = &b->ht[from_hash(h >> 16)]; *fp; fp = &(*fp)->next) {
        if (*fp == f) {
            tcf_tree_lock(tp);
            *fp = f->next;
            tcf_tree_unlock(tp);

            route4_reset_fastmap(tp->q, head, f->id);
            route4_delete_filter(tp, f);

            /* Strip tree */

            for (i = 0; i <= 32; i++)
                if (b->ht[i])
                    return 0;

            /* OK, session has no flows */
            tcf_tree_lock(tp);
            head->table[to_hash(h)] = NULL;
            tcf_tree_unlock(tp);

            kfree(b);
            return 0;
        }
    }
    return 0;
}

static const struct nla_policy route4_policy[TCA_ROUTE4_MAX + 1] = {
    [TCA_ROUTE4_CLASSID]    = { .type = NLA_U32 },
    [TCA_ROUTE4_TO]     = { .type = NLA_U32 },
    [TCA_ROUTE4_FROM]   = { .type = NLA_U32 },
    [TCA_ROUTE4_IIF]    = { .type = NLA_U32 },
};

static int route4_set_parms(struct tcf_proto *tp, unsigned long base,
    struct route4_filter *f, u32 handle, struct route4_head *head,
    struct nlattr **tb, struct nlattr *est, int new)
{
    int err;
    u32 id = 0, to = 0, nhandle = 0x8000;
    struct route4_filter *fp;
    unsigned int h1;
    struct route4_bucket *b;
    struct tcf_exts e;

    err = tcf_exts_validate(tp, tb, est, &e, &route_ext_map);
    if (err < 0)
        return err;

    err = -EINVAL;
    if (tb[TCA_ROUTE4_TO]) {
        if (new && handle & 0x8000)
            goto errout;
        to = nla_get_u32(tb[TCA_ROUTE4_TO]);
        if (to > 0xFF)
            goto errout;
        nhandle = to;
    }

    if (tb[TCA_ROUTE4_FROM]) {
        if (tb[TCA_ROUTE4_IIF])
            goto errout;
        id = nla_get_u32(tb[TCA_ROUTE4_FROM]);
        if (id > 0xFF)
            goto errout;
        nhandle |= id << 16;
    } else if (tb[TCA_ROUTE4_IIF]) {
        id = nla_get_u32(tb[TCA_ROUTE4_IIF]);
        if (id > 0x7FFF)
            goto errout;
        nhandle |= (id | 0x8000) << 16;
    } else
        nhandle |= 0xFFFF << 16;

    if (handle && new) {
        nhandle |= handle & 0x7F00;
        if (nhandle != handle)
            goto errout;
    }

    h1 = to_hash(nhandle);
    b = head->table[h1];
    if (!b) {
        err = -ENOBUFS;
        b = kzalloc(sizeof(struct route4_bucket), GFP_KERNEL);
        if (b == NULL)
            goto errout;

        tcf_tree_lock(tp);
        head->table[h1] = b;
        tcf_tree_unlock(tp);
    } else {
        unsigned int h2 = from_hash(nhandle >> 16);

        err = -EEXIST;
        for (fp = b->ht[h2]; fp; fp = fp->next)
            if (fp->handle == f->handle)
                goto errout;
    }

    tcf_tree_lock(tp);
    if (tb[TCA_ROUTE4_TO])
        f->id = to;

    if (tb[TCA_ROUTE4_FROM])
        f->id = to | id<<16;
    else if (tb[TCA_ROUTE4_IIF])
        f->iif = id;

    f->handle = nhandle;
    f->bkt = b;
    tcf_tree_unlock(tp);

    if (tb[TCA_ROUTE4_CLASSID]) {
        f->res.classid = nla_get_u32(tb[TCA_ROUTE4_CLASSID]);
        tcf_bind_filter(tp, &f->res, base);
    }

    tcf_exts_change(tp, &f->exts, &e);

    return 0;
errout:
    tcf_exts_destroy(tp, &e);
    return err;
}

static int route4_change(struct sk_buff *in_skb,
               struct tcf_proto *tp, unsigned long base,
               u32 handle,
               struct nlattr **tca,
               unsigned long *arg)
{
    struct route4_head *head = tp->root;
    struct route4_filter *f, *f1, **fp;
    struct route4_bucket *b;
    struct nlattr *opt = tca[TCA_OPTIONS];
    struct nlattr *tb[TCA_ROUTE4_MAX + 1];
    unsigned int h, th;
    u32 old_handle = 0;
    int err;

    if (opt == NULL)
        return handle ? -EINVAL : 0;

    err = nla_parse_nested(tb, TCA_ROUTE4_MAX, opt, route4_policy);
    if (err < 0)
        return err;

    f = (struct route4_filter *)*arg;
    if (f) {
        if (f->handle != handle && handle)
            return -EINVAL;

        if (f->bkt)
            old_handle = f->handle;

        err = route4_set_parms(tp, base, f, handle, head, tb,
            tca[TCA_RATE], 0);
        if (err < 0)
            return err;

        goto reinsert;
    }

    err = -ENOBUFS;
    if (head == NULL) {
        head = kzalloc(sizeof(struct route4_head), GFP_KERNEL);
        if (head == NULL)
            goto errout;

        tcf_tree_lock(tp);
        tp->root = head;
        tcf_tree_unlock(tp);
    }

    f = kzalloc(sizeof(struct route4_filter), GFP_KERNEL);
    if (f == NULL)
        goto errout;

    err = route4_set_parms(tp, base, f, handle, head, tb,
        tca[TCA_RATE], 1);
    if (err < 0)
        goto errout;

reinsert:
    h = from_hash(f->handle >> 16);
    for (fp = &f->bkt->ht[h]; (f1 = *fp) != NULL; fp = &f1->next)
        if (f->handle < f1->handle)
            break;

    f->next = f1;
    tcf_tree_lock(tp);
    *fp = f;

    if (old_handle && f->handle != old_handle) {
        th = to_hash(old_handle);
        h = from_hash(old_handle >> 16);
        b = head->table[th];
        if (b) {
            for (fp = &b->ht[h]; *fp; fp = &(*fp)->next) {
                if (*fp == f) {
                    *fp = f->next;
                    break;
                }
            }
        }
    }
    tcf_tree_unlock(tp);

    route4_reset_fastmap(tp->q, head, f->id);
    *arg = (unsigned long)f;
    return 0;

errout:
    kfree(f);
    return err;
}

static void route4_walk(struct tcf_proto *tp, struct tcf_walker *arg)
{
    struct route4_head *head = tp->root;
    unsigned int h, h1;

    if (head == NULL)
        arg->stop = 1;

    if (arg->stop)
        return;

    for (h = 0; h <= 256; h++) {
        struct route4_bucket *b = head->table[h];

        if (b) {
            for (h1 = 0; h1 <= 32; h1++) {
                struct route4_filter *f;

                for (f = b->ht[h1]; f; f = f->next) {
                    if (arg->count < arg->skip) {
                        arg->count++;
                        continue;
                    }
                    if (arg->fn(tp, (unsigned long)f, arg) < 0) {
                        arg->stop = 1;
                        return;
                    }
                    arg->count++;
                }
            }
        }
    }
}

static int route4_dump(struct tcf_proto *tp, unsigned long fh,
               struct sk_buff *skb, struct tcmsg *t)
{
    struct route4_filter *f = (struct route4_filter *)fh;
    unsigned char *b = skb_tail_pointer(skb);
    struct nlattr *nest;
    u32 id;

    if (f == NULL)
        return skb->len;

    t->tcm_handle = f->handle;

    nest = nla_nest_start(skb, TCA_OPTIONS);
    if (nest == NULL)
        goto nla_put_failure;

    if (!(f->handle & 0x8000)) {
        id = f->id & 0xFF;
        if (nla_put_u32(skb, TCA_ROUTE4_TO, id))
            goto nla_put_failure;
    }
    if (f->handle & 0x80000000) {
        if ((f->handle >> 16) != 0xFFFF &&
            nla_put_u32(skb, TCA_ROUTE4_IIF, f->iif))
            goto nla_put_failure;
    } else {
        id = f->id >> 16;
        if (nla_put_u32(skb, TCA_ROUTE4_FROM, id))
            goto nla_put_failure;
    }
    if (f->res.classid &&
        nla_put_u32(skb, TCA_ROUTE4_CLASSID, f->res.classid))
        goto nla_put_failure;

    if (tcf_exts_dump(skb, &f->exts, &route_ext_map) < 0)
        goto nla_put_failure;

    nla_nest_end(skb, nest);

    if (tcf_exts_dump_stats(skb, &f->exts, &route_ext_map) < 0)
        goto nla_put_failure;

    return skb->len;

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

static struct tcf_proto_ops cls_route4_ops __read_mostly = {
    .kind       =   "route",
    .classify   =   route4_classify,
    .init       =   route4_init,
    .destroy    =   route4_destroy,
    .get        =   route4_get,
    .put        =   route4_put,
    .change     =   route4_change,
    .delete     =   route4_delete,
    .walk       =   route4_walk,
    .dump       =   route4_dump,
    .owner      =   THIS_MODULE,
};

static int __init init_route4(void)
{
    return register_tcf_proto_ops(&cls_route4_ops);
}

static void __exit exit_route4(void)
{
    unregister_tcf_proto_ops(&cls_route4_ops);
}

module_init(init_route4)
module_exit(exit_route4)
MODULE_LICENSE("GPL");