cls_tcindex.c
// SPDX-License-Identifier: GPL-2.0-only
/*
* net/sched/cls_tcindex.c Packet classifier for skb->tc_index
*
* Written 1998,1999 by Werner Almesberger, EPFL ICA
*/
#include <linux/module.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/skbuff.h>
#include <linux/errno.h>
#include <linux/slab.h>
#include <linux/refcount.h>
#include <net/act_api.h>
#include <net/netlink.h>
#include <net/pkt_cls.h>
#include <net/sch_generic.h>
/*
* Passing parameters to the root seems to be done more awkwardly than really
* necessary. At least, u32 doesn't seem to use such dirty hacks. To be
* verified. FIXME.
*/
#define PERFECT_HASH_THRESHOLD 64 /* use perfect hash if not bigger */
#define DEFAULT_HASH_SIZE 64 /* optimized for diffserv */
struct tcindex_data;
struct tcindex_filter_result {
struct tcf_exts exts;
struct tcf_result res;
struct tcindex_data *p;
struct rcu_work rwork;
};
struct tcindex_filter {
u16 key;
struct tcindex_filter_result result;
struct tcindex_filter __rcu *next;
struct rcu_work rwork;
};
struct tcindex_data {
struct tcindex_filter_result *perfect; /* perfect hash; NULL if none */
struct tcindex_filter __rcu **h; /* imperfect hash; */
struct tcf_proto *tp;
u16 mask; /* AND key with mask */
u32 shift; /* shift ANDed key to the right */
u32 hash; /* hash table size; 0 if undefined */
u32 alloc_hash; /* allocated size */
u32 fall_through; /* 0: only classify if explicit match */
refcount_t refcnt; /* a temporary refcnt for perfect hash */
struct rcu_work rwork;
};
static inline int tcindex_filter_is_set(struct tcindex_filter_result *r)
{
return tcf_exts_has_actions(&r->exts) || r->res.classid;
}
static void tcindex_data_get(struct tcindex_data *p)
{
refcount_inc(&p->refcnt);
}
static void tcindex_data_put(struct tcindex_data *p)
{
if (refcount_dec_and_test(&p->refcnt)) {
kfree(p->perfect);
kfree(p->h);
kfree(p);
}
}
static struct tcindex_filter_result *tcindex_lookup(struct tcindex_data *p,
u16 key)
{
if (p->perfect) {
struct tcindex_filter_result *f = p->perfect + key;
return tcindex_filter_is_set(f) ? f : NULL;
} else if (p->h) {
struct tcindex_filter __rcu **fp;
struct tcindex_filter *f;
fp = &p->h[key % p->hash];
for (f = rcu_dereference_bh_rtnl(*fp);
f;
fp = &f->next, f = rcu_dereference_bh_rtnl(*fp))
if (f->key == key)
return &f->result;
}
return NULL;
}
static int tcindex_classify(struct sk_buff *skb, const struct tcf_proto *tp,
struct tcf_result *res)
{
struct tcindex_data *p = rcu_dereference_bh(tp->root);
struct tcindex_filter_result *f;
int key = (skb->tc_index & p->mask) >> p->shift;
pr_debug("tcindex_classify(skb %p,tp %p,res %p),p %p\n",
skb, tp, res, p);
f = tcindex_lookup(p, key);
if (!f) {
struct Qdisc *q = tcf_block_q(tp->chain->block);
if (!p->fall_through)
return -1;
res->classid = TC_H_MAKE(TC_H_MAJ(q->handle), key);
res->class = 0;
pr_debug("alg 0x%x\n", res->classid);
return 0;
}
*res = f->res;
pr_debug("map 0x%x\n", res->classid);
return tcf_exts_exec(skb, &f->exts, res);
}
static void *tcindex_get(struct tcf_proto *tp, u32 handle)
{
struct tcindex_data *p = rtnl_dereference(tp->root);
struct tcindex_filter_result *r;
pr_debug("tcindex_get(tp %p,handle 0x%08x)\n", tp, handle);
if (p->perfect && handle >= p->alloc_hash)
return NULL;
r = tcindex_lookup(p, handle);
return r && tcindex_filter_is_set(r) ? r : NULL;
}
static int tcindex_init(struct tcf_proto *tp)
{
struct tcindex_data *p;
pr_debug("tcindex_init(tp %p)\n", tp);
p = kzalloc(sizeof(struct tcindex_data), GFP_KERNEL);
if (!p)
return -ENOMEM;
p->mask = 0xffff;
p->hash = DEFAULT_HASH_SIZE;
p->fall_through = 1;
refcount_set(&p->refcnt, 1); /* Paired with tcindex_destroy_work() */
rcu_assign_pointer(tp->root, p);
return 0;
}
static void __tcindex_destroy_rexts(struct tcindex_filter_result *r)
{
tcf_exts_destroy(&r->exts);
tcf_exts_put_net(&r->exts);
tcindex_data_put(r->p);
}
static void tcindex_destroy_rexts_work(struct work_struct *work)
{
struct tcindex_filter_result *r;
r = container_of(to_rcu_work(work),
struct tcindex_filter_result,
rwork);
rtnl_lock();
__tcindex_destroy_rexts(r);
rtnl_unlock();
}
static void __tcindex_destroy_fexts(struct tcindex_filter *f)
{
tcf_exts_destroy(&f->result.exts);
tcf_exts_put_net(&f->result.exts);
kfree(f);
}
static void tcindex_destroy_fexts_work(struct work_struct *work)
{
struct tcindex_filter *f = container_of(to_rcu_work(work),
struct tcindex_filter,
rwork);
rtnl_lock();
__tcindex_destroy_fexts(f);
rtnl_unlock();
}
static int tcindex_delete(struct tcf_proto *tp, void *arg, bool *last,
bool rtnl_held, struct netlink_ext_ack *extack)
{
struct tcindex_data *p = rtnl_dereference(tp->root);
struct tcindex_filter_result *r = arg;
struct tcindex_filter __rcu **walk;
struct tcindex_filter *f = NULL;
pr_debug("tcindex_delete(tp %p,arg %p),p %p\n", tp, arg, p);
if (p->perfect) {
if (!r->res.class)
return -ENOENT;
} else {
int i;
for (i = 0; i < p->hash; i++) {
walk = p->h + i;
for (f = rtnl_dereference(*walk); f;
walk = &f->next, f = rtnl_dereference(*walk)) {
if (&f->result == r)
goto found;
}
}
return -ENOENT;
found:
rcu_assign_pointer(*walk, rtnl_dereference(f->next));
}
tcf_unbind_filter(tp, &r->res);
/* all classifiers are required to call tcf_exts_destroy() after rcu
* grace period, since converted-to-rcu actions are relying on that
* in cleanup() callback
*/
if (f) {
if (tcf_exts_get_net(&f->result.exts))
tcf_queue_work(&f->rwork, tcindex_destroy_fexts_work);
else
__tcindex_destroy_fexts(f);
} else {
tcindex_data_get(p);
if (tcf_exts_get_net(&r->exts))
tcf_queue_work(&r->rwork, tcindex_destroy_rexts_work);
else
__tcindex_destroy_rexts(r);
}
*last = false;
return 0;
}
static void tcindex_destroy_work(struct work_struct *work)
{
struct tcindex_data *p = container_of(to_rcu_work(work),
struct tcindex_data,
rwork);
tcindex_data_put(p);
}
static inline int
valid_perfect_hash(struct tcindex_data *p)
{
return p->hash > (p->mask >> p->shift);
}
static const struct nla_policy tcindex_policy[TCA_TCINDEX_MAX + 1] = {
[TCA_TCINDEX_HASH] = { .type = NLA_U32 },
[TCA_TCINDEX_MASK] = { .type = NLA_U16 },
[TCA_TCINDEX_SHIFT] = { .type = NLA_U32 },
[TCA_TCINDEX_FALL_THROUGH] = { .type = NLA_U32 },
[TCA_TCINDEX_CLASSID] = { .type = NLA_U32 },
};
static int tcindex_filter_result_init(struct tcindex_filter_result *r,
struct tcindex_data *p,
struct net *net)
{
memset(r, 0, sizeof(*r));
r->p = p;
return tcf_exts_init(&r->exts, net, TCA_TCINDEX_ACT,
TCA_TCINDEX_POLICE);
}
static void tcindex_free_perfect_hash(struct tcindex_data *cp);
static void tcindex_partial_destroy_work(struct work_struct *work)
{
struct tcindex_data *p = container_of(to_rcu_work(work),
struct tcindex_data,
rwork);
rtnl_lock();
if (p->perfect)
tcindex_free_perfect_hash(p);
kfree(p);
rtnl_unlock();
}
static void tcindex_free_perfect_hash(struct tcindex_data *cp)
{
int i;
for (i = 0; i < cp->hash; i++)
tcf_exts_destroy(&cp->perfect[i].exts);
kfree(cp->perfect);
}
static int tcindex_alloc_perfect_hash(struct net *net, struct tcindex_data *cp)
{
int i, err = 0;
cp->perfect = kcalloc(cp->hash, sizeof(struct tcindex_filter_result),
GFP_KERNEL | __GFP_NOWARN);
if (!cp->perfect)
return -ENOMEM;
for (i = 0; i < cp->hash; i++) {
err = tcf_exts_init(&cp->perfect[i].exts, net,
TCA_TCINDEX_ACT, TCA_TCINDEX_POLICE);
if (err < 0)
goto errout;
cp->perfect[i].p = cp;
}
return 0;
errout:
tcindex_free_perfect_hash(cp);
return err;
}
static int
tcindex_set_parms(struct net *net, struct tcf_proto *tp, unsigned long base,
u32 handle, struct tcindex_data *p,
struct tcindex_filter_result *r, struct nlattr **tb,
struct nlattr *est, bool ovr, struct netlink_ext_ack *extack)
{
struct tcindex_filter_result new_filter_result, *old_r = r;
struct tcindex_data *cp = NULL, *oldp;
struct tcindex_filter *f = NULL; /* make gcc behave */
struct tcf_result cr = {};
int err, balloc = 0;
struct tcf_exts e;
err = tcf_exts_init(&e, net, TCA_TCINDEX_ACT, TCA_TCINDEX_POLICE);
if (err < 0)
return err;
err = tcf_exts_validate(net, tp, tb, est, &e, ovr, true, extack);
if (err < 0)
goto errout;
err = -ENOMEM;
/* tcindex_data attributes must look atomic to classifier/lookup so
* allocate new tcindex data and RCU assign it onto root. Keeping
* perfect hash and hash pointers from old data.
*/
cp = kzalloc(sizeof(*cp), GFP_KERNEL);
if (!cp)
goto errout;
cp->mask = p->mask;
cp->shift = p->shift;
cp->hash = p->hash;
cp->alloc_hash = p->alloc_hash;
cp->fall_through = p->fall_through;
cp->tp = tp;
refcount_set(&cp->refcnt, 1); /* Paired with tcindex_destroy_work() */
if (tb[TCA_TCINDEX_HASH])
cp->hash = nla_get_u32(tb[TCA_TCINDEX_HASH]);
if (tb[TCA_TCINDEX_MASK])
cp->mask = nla_get_u16(tb[TCA_TCINDEX_MASK]);
if (tb[TCA_TCINDEX_SHIFT]) {
cp->shift = nla_get_u32(tb[TCA_TCINDEX_SHIFT]);
if (cp->shift > 16) {
err = -EINVAL;
goto errout;
}
}
if (!cp->hash) {
/* Hash not specified, use perfect hash if the upper limit
* of the hashing index is below the threshold.
*/
if ((cp->mask >> cp->shift) < PERFECT_HASH_THRESHOLD)
cp->hash = (cp->mask >> cp->shift) + 1;
else
cp->hash = DEFAULT_HASH_SIZE;
}
if (p->perfect) {
int i;
if (tcindex_alloc_perfect_hash(net, cp) < 0)
goto errout;
cp->alloc_hash = cp->hash;
for (i = 0; i < min(cp->hash, p->hash); i++)
cp->perfect[i].res = p->perfect[i].res;
balloc = 1;
}
cp->h = p->h;
err = tcindex_filter_result_init(&new_filter_result, cp, net);
if (err < 0)
goto errout_alloc;
if (old_r)
cr = r->res;
err = -EBUSY;
/* Hash already allocated, make sure that we still meet the
* requirements for the allocated hash.
*/
if (cp->perfect) {
if (!valid_perfect_hash(cp) ||
cp->hash > cp->alloc_hash)
goto errout_alloc;
} else if (cp->h && cp->hash != cp->alloc_hash) {
goto errout_alloc;
}
err = -EINVAL;
if (tb[TCA_TCINDEX_FALL_THROUGH])
cp->fall_through = nla_get_u32(tb[TCA_TCINDEX_FALL_THROUGH]);
if (!cp->perfect && !cp->h)
cp->alloc_hash = cp->hash;
/* Note: this could be as restrictive as if (handle & ~(mask >> shift))
* but then, we'd fail handles that may become valid after some future
* mask change. While this is extremely unlikely to ever matter,
* the check below is safer (and also more backwards-compatible).
*/
if (cp->perfect || valid_perfect_hash(cp))
if (handle >= cp->alloc_hash)
goto errout_alloc;
err = -ENOMEM;
if (!cp->perfect && !cp->h) {
if (valid_perfect_hash(cp)) {
if (tcindex_alloc_perfect_hash(net, cp) < 0)
goto errout_alloc;
balloc = 1;
} else {
struct tcindex_filter __rcu **hash;
hash = kcalloc(cp->hash,
sizeof(struct tcindex_filter *),
GFP_KERNEL);
if (!hash)
goto errout_alloc;
cp->h = hash;
balloc = 2;
}
}
if (cp->perfect)
r = cp->perfect + handle;
else
r = tcindex_lookup(cp, handle) ? : &new_filter_result;
if (r == &new_filter_result) {
f = kzalloc(sizeof(*f), GFP_KERNEL);
if (!f)
goto errout_alloc;
f->key = handle;
f->next = NULL;
err = tcindex_filter_result_init(&f->result, cp, net);
if (err < 0) {
kfree(f);
goto errout_alloc;
}
}
if (tb[TCA_TCINDEX_CLASSID]) {
cr.classid = nla_get_u32(tb[TCA_TCINDEX_CLASSID]);
tcf_bind_filter(tp, &cr, base);
}
if (old_r && old_r != r) {
err = tcindex_filter_result_init(old_r, cp, net);
if (err < 0) {
kfree(f);
goto errout_alloc;
}
}
oldp = p;
r->res = cr;
tcf_exts_change(&r->exts, &e);
rcu_assign_pointer(tp->root, cp);
if (r == &new_filter_result) {
struct tcindex_filter *nfp;
struct tcindex_filter __rcu **fp;
f->result.res = r->res;
tcf_exts_change(&f->result.exts, &r->exts);
fp = cp->h + (handle % cp->hash);
for (nfp = rtnl_dereference(*fp);
nfp;
fp = &nfp->next, nfp = rtnl_dereference(*fp))
; /* nothing */
rcu_assign_pointer(*fp, f);
} else {
tcf_exts_destroy(&new_filter_result.exts);
}
if (oldp)
tcf_queue_work(&oldp->rwork, tcindex_partial_destroy_work);
return 0;
errout_alloc:
if (balloc == 1)
tcindex_free_perfect_hash(cp);
else if (balloc == 2)
kfree(cp->h);
tcf_exts_destroy(&new_filter_result.exts);
errout:
kfree(cp);
tcf_exts_destroy(&e);
return err;
}
static int
tcindex_change(struct net *net, struct sk_buff *in_skb,
struct tcf_proto *tp, unsigned long base, u32 handle,
struct nlattr **tca, void **arg, bool ovr,
bool rtnl_held, struct netlink_ext_ack *extack)
{
struct nlattr *opt = tca[TCA_OPTIONS];
struct nlattr *tb[TCA_TCINDEX_MAX + 1];
struct tcindex_data *p = rtnl_dereference(tp->root);
struct tcindex_filter_result *r = *arg;
int err;
pr_debug("tcindex_change(tp %p,handle 0x%08x,tca %p,arg %p),opt %p,"
"p %p,r %p,*arg %p\n",
tp, handle, tca, arg, opt, p, r, *arg);
if (!opt)
return 0;
err = nla_parse_nested_deprecated(tb, TCA_TCINDEX_MAX, opt,
tcindex_policy, NULL);
if (err < 0)
return err;
return tcindex_set_parms(net, tp, base, handle, p, r, tb,
tca[TCA_RATE], ovr, extack);
}
static void tcindex_walk(struct tcf_proto *tp, struct tcf_walker *walker,
bool rtnl_held)
{
struct tcindex_data *p = rtnl_dereference(tp->root);
struct tcindex_filter *f, *next;
int i;
pr_debug("tcindex_walk(tp %p,walker %p),p %p\n", tp, walker, p);
if (p->perfect) {
for (i = 0; i < p->hash; i++) {
if (!p->perfect[i].res.class)
continue;
if (walker->count >= walker->skip) {
if (walker->fn(tp, p->perfect + i, walker) < 0) {
walker->stop = 1;
return;
}
}
walker->count++;
}
}
if (!p->h)
return;
for (i = 0; i < p->hash; i++) {
for (f = rtnl_dereference(p->h[i]); f; f = next) {
next = rtnl_dereference(f->next);
if (walker->count >= walker->skip) {
if (walker->fn(tp, &f->result, walker) < 0) {
walker->stop = 1;
return;
}
}
walker->count++;
}
}
}
static void tcindex_destroy(struct tcf_proto *tp, bool rtnl_held,
struct netlink_ext_ack *extack)
{
struct tcindex_data *p = rtnl_dereference(tp->root);
int i;
pr_debug("tcindex_destroy(tp %p),p %p\n", tp, p);
if (p->perfect) {
for (i = 0; i < p->hash; i++) {
struct tcindex_filter_result *r = p->perfect + i;
/* tcf_queue_work() does not guarantee the ordering we
* want, so we have to take this refcnt temporarily to
* ensure 'p' is freed after all tcindex_filter_result
* here. Imperfect hash does not need this, because it
* uses linked lists rather than an array.
*/
tcindex_data_get(p);
tcf_unbind_filter(tp, &r->res);
if (tcf_exts_get_net(&r->exts))
tcf_queue_work(&r->rwork,
tcindex_destroy_rexts_work);
else
__tcindex_destroy_rexts(r);
}
}
for (i = 0; p->h && i < p->hash; i++) {
struct tcindex_filter *f, *next;
bool last;
for (f = rtnl_dereference(p->h[i]); f; f = next) {
next = rtnl_dereference(f->next);
tcindex_delete(tp, &f->result, &last, rtnl_held, NULL);
}
}
tcf_queue_work(&p->rwork, tcindex_destroy_work);
}
static int tcindex_dump(struct net *net, struct tcf_proto *tp, void *fh,
struct sk_buff *skb, struct tcmsg *t, bool rtnl_held)
{
struct tcindex_data *p = rtnl_dereference(tp->root);
struct tcindex_filter_result *r = fh;
struct nlattr *nest;
pr_debug("tcindex_dump(tp %p,fh %p,skb %p,t %p),p %p,r %p\n",
tp, fh, skb, t, p, r);
pr_debug("p->perfect %p p->h %p\n", p->perfect, p->h);
nest = nla_nest_start_noflag(skb, TCA_OPTIONS);
if (nest == NULL)
goto nla_put_failure;
if (!fh) {
t->tcm_handle = ~0; /* whatever ... */
if (nla_put_u32(skb, TCA_TCINDEX_HASH, p->hash) ||
nla_put_u16(skb, TCA_TCINDEX_MASK, p->mask) ||
nla_put_u32(skb, TCA_TCINDEX_SHIFT, p->shift) ||
nla_put_u32(skb, TCA_TCINDEX_FALL_THROUGH, p->fall_through))
goto nla_put_failure;
nla_nest_end(skb, nest);
} else {
if (p->perfect) {
t->tcm_handle = r - p->perfect;
} else {
struct tcindex_filter *f;
struct tcindex_filter __rcu **fp;
int i;
t->tcm_handle = 0;
for (i = 0; !t->tcm_handle && i < p->hash; i++) {
fp = &p->h[i];
for (f = rtnl_dereference(*fp);
!t->tcm_handle && f;
fp = &f->next, f = rtnl_dereference(*fp)) {
if (&f->result == r)
t->tcm_handle = f->key;
}
}
}
pr_debug("handle = %d\n", t->tcm_handle);
if (r->res.class &&
nla_put_u32(skb, TCA_TCINDEX_CLASSID, r->res.classid))
goto nla_put_failure;
if (tcf_exts_dump(skb, &r->exts) < 0)
goto nla_put_failure;
nla_nest_end(skb, nest);
if (tcf_exts_dump_stats(skb, &r->exts) < 0)
goto nla_put_failure;
}
return skb->len;
nla_put_failure:
nla_nest_cancel(skb, nest);
return -1;
}
static void tcindex_bind_class(void *fh, u32 classid, unsigned long cl,
void *q, unsigned long base)
{
struct tcindex_filter_result *r = fh;
if (r && r->res.classid == classid) {
if (cl)
__tcf_bind_filter(q, &r->res, base);
else
__tcf_unbind_filter(q, &r->res);
}
}
static struct tcf_proto_ops cls_tcindex_ops __read_mostly = {
.kind = "tcindex",
.classify = tcindex_classify,
.init = tcindex_init,
.destroy = tcindex_destroy,
.get = tcindex_get,
.change = tcindex_change,
.delete = tcindex_delete,
.walk = tcindex_walk,
.dump = tcindex_dump,
.bind_class = tcindex_bind_class,
.owner = THIS_MODULE,
};
static int __init init_tcindex(void)
{
return register_tcf_proto_ops(&cls_tcindex_ops);
}
static void __exit exit_tcindex(void)
{
unregister_tcf_proto_ops(&cls_tcindex_ops);
}
module_init(init_tcindex)
module_exit(exit_tcindex)
MODULE_LICENSE("GPL");