linux/net/sched/cls_api.c
Patrick McHardy 47a1a1d4be pkt_sched: remove unnecessary xchg() in packet classifiers
The use of xchg() hasn't been necessary since 2.2.something when proper
locking was added to packet schedulers. In the case of classifiers they
mostly weren't even necessary before that since they're mainly used
to assign a NULL pointer to the filter root in the ->destroy path;
the root is destroyed immediately after that.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
2008-11-20 04:14:28 -08:00

604 lines
14 KiB
C

/*
* 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, <kuznet@ms2.inr.ac.ru>
*
* Changes:
*
* Eduardo J. Blanco <ejbs@netlabs.com.uy> :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 <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 struct tcf_proto_ops *tcf_proto_lookup_ops(struct nlattr *kind)
{
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 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;
struct tcf_proto_ops *tp_ops;
const struct Qdisc_class_ops *cops;
unsigned long cl;
unsigned long fh;
int err;
if (net != &init_net)
return -EINVAL;
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(&init_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) {
struct netdev_queue *dev_queue = netdev_get_tx_queue(dev, 0);
q = dev_queue->qdisc_sleeping;
parent = q->handle;
} else {
q = qdisc_lookup(dev, TC_H_MAJ(t->tcm_parent));
if (q == NULL)
return -EINVAL;
}
/* Is it classful? */
if ((cops = q->ops->cl_ops) == NULL)
return -EINVAL;
/* 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 ? : 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;
}
spin_lock_bh(root_lock);
tp->next = *back;
*back = tp;
spin_unlock_bh(root_lock);
} 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(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)
goto errout;
break;
case RTM_DELTFILTER:
err = tp->ops->delete(tp, fh);
if (err == 0)
tfilter_notify(skb, n, tp, fh, RTM_DELTFILTER);
goto errout;
case RTM_GETTFILTER:
err = tfilter_notify(skb, n, tp, fh, RTM_NEWTFILTER);
goto errout;
default:
err = -EINVAL;
goto errout;
}
}
err = tp->ops->change(tp, cl, t->tcm_handle, tca, &fh);
if (err == 0)
tfilter_notify(skb, n, tp, fh, RTM_NEWTFILTER);
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 pid, u32 seq, u16 flags, int event)
{
struct tcmsg *tcm;
struct nlmsghdr *nlh;
unsigned char *b = skb_tail_pointer(skb);
nlh = NLMSG_NEW(skb, pid, seq, event, sizeof(*tcm), flags);
tcm = NLMSG_DATA(nlh);
tcm->tcm_family = AF_UNSPEC;
tcm->tcm__pad1 = 0;
tcm->tcm__pad1 = 0;
tcm->tcm_ifindex = qdisc_dev(tp->q)->ifindex;
tcm->tcm_parent = tp->classid;
tcm->tcm_info = TC_H_MAKE(tp->prio, tp->protocol);
NLA_PUT_STRING(skb, TCA_KIND, tp->ops->kind);
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;
nlmsg_failure:
nla_put_failure:
nlmsg_trim(skb, b);
return -1;
}
static int tfilter_notify(struct sk_buff *oskb, struct nlmsghdr *n,
struct tcf_proto *tp, unsigned long fh, int event)
{
struct sk_buff *skb;
u32 pid = oskb ? NETLINK_CB(oskb).pid : 0;
skb = alloc_skb(NLMSG_GOODSIZE, GFP_KERNEL);
if (!skb)
return -ENOBUFS;
if (tcf_fill_node(skb, tp, fh, pid, n->nlmsg_seq, 0, event) <= 0) {
kfree_skb(skb);
return -EINVAL;
}
return rtnetlink_send(skb, &init_net, pid, 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).pid,
a->cb->nlh->nlmsg_seq, NLM_F_MULTI, RTM_NEWTFILTER);
}
static int tc_dump_tfilter(struct sk_buff *skb, struct netlink_callback *cb)
{
struct net *net = sock_net(skb->sk);
struct netdev_queue *dev_queue;
int t;
int s_t;
struct net_device *dev;
struct Qdisc *q;
struct tcf_proto *tp, **chain;
struct tcmsg *tcm = (struct tcmsg *)NLMSG_DATA(cb->nlh);
unsigned long cl = 0;
const struct Qdisc_class_ops *cops;
struct tcf_dump_args arg;
if (net != &init_net)
return 0;
if (cb->nlh->nlmsg_len < NLMSG_LENGTH(sizeof(*tcm)))
return skb->len;
if ((dev = dev_get_by_index(&init_net, tcm->tcm_ifindex)) == NULL)
return skb->len;
dev_queue = netdev_get_tx_queue(dev, 0);
if (!tcm->tcm_parent)
q = dev_queue->qdisc_sleeping;
else
q = qdisc_lookup(dev, TC_H_MAJ(tcm->tcm_parent));
if (!q)
goto out;
if ((cops = q->ops->cl_ops) == 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).pid,
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:
dev_put(dev);
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);
rtnl_register(PF_UNSPEC, RTM_DELTFILTER, tc_ctl_tfilter, NULL);
rtnl_register(PF_UNSPEC, RTM_GETTFILTER, tc_ctl_tfilter,
tc_dump_tfilter);
return 0;
}
subsys_initcall(tc_filter_init);