linux/net/core/fib_rules.c

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/*
* net/core/fib_rules.c Generic Routing Rules
*
* 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, version 2.
*
* Authors: Thomas Graf <tgraf@suug.ch>
*/
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/list.h>
#include <net/fib_rules.h>
static LIST_HEAD(rules_ops);
static DEFINE_SPINLOCK(rules_mod_lock);
static void notify_rule_change(int event, struct fib_rule *rule,
struct fib_rules_ops *ops, struct nlmsghdr *nlh,
u32 pid);
static struct fib_rules_ops *lookup_rules_ops(int family)
{
struct fib_rules_ops *ops;
rcu_read_lock();
list_for_each_entry_rcu(ops, &rules_ops, list) {
if (ops->family == family) {
if (!try_module_get(ops->owner))
ops = NULL;
rcu_read_unlock();
return ops;
}
}
rcu_read_unlock();
return NULL;
}
static void rules_ops_put(struct fib_rules_ops *ops)
{
if (ops)
module_put(ops->owner);
}
int fib_rules_register(struct fib_rules_ops *ops)
{
int err = -EEXIST;
struct fib_rules_ops *o;
if (ops->rule_size < sizeof(struct fib_rule))
return -EINVAL;
if (ops->match == NULL || ops->configure == NULL ||
ops->compare == NULL || ops->fill == NULL ||
ops->action == NULL)
return -EINVAL;
spin_lock(&rules_mod_lock);
list_for_each_entry(o, &rules_ops, list)
if (ops->family == o->family)
goto errout;
list_add_tail_rcu(&ops->list, &rules_ops);
err = 0;
errout:
spin_unlock(&rules_mod_lock);
return err;
}
EXPORT_SYMBOL_GPL(fib_rules_register);
static void cleanup_ops(struct fib_rules_ops *ops)
{
struct fib_rule *rule, *tmp;
list_for_each_entry_safe(rule, tmp, ops->rules_list, list) {
list_del_rcu(&rule->list);
fib_rule_put(rule);
}
}
int fib_rules_unregister(struct fib_rules_ops *ops)
{
int err = 0;
struct fib_rules_ops *o;
spin_lock(&rules_mod_lock);
list_for_each_entry(o, &rules_ops, list) {
if (o == ops) {
list_del_rcu(&o->list);
cleanup_ops(ops);
goto out;
}
}
err = -ENOENT;
out:
spin_unlock(&rules_mod_lock);
synchronize_rcu();
return err;
}
EXPORT_SYMBOL_GPL(fib_rules_unregister);
static int fib_rule_match(struct fib_rule *rule, struct fib_rules_ops *ops,
struct flowi *fl, int flags)
{
int ret = 0;
if (rule->ifindex && (rule->ifindex != fl->iif))
goto out;
if ((rule->mark ^ fl->mark) & rule->mark_mask)
goto out;
ret = ops->match(rule, fl, flags);
out:
return (rule->flags & FIB_RULE_INVERT) ? !ret : ret;
}
int fib_rules_lookup(struct fib_rules_ops *ops, struct flowi *fl,
int flags, struct fib_lookup_arg *arg)
{
struct fib_rule *rule;
int err;
rcu_read_lock();
list_for_each_entry_rcu(rule, ops->rules_list, list) {
if (!fib_rule_match(rule, ops, fl, flags))
continue;
err = ops->action(rule, fl, flags, arg);
if (err != -EAGAIN) {
fib_rule_get(rule);
arg->rule = rule;
goto out;
}
}
err = -ESRCH;
out:
rcu_read_unlock();
return err;
}
EXPORT_SYMBOL_GPL(fib_rules_lookup);
static int validate_rulemsg(struct fib_rule_hdr *frh, struct nlattr **tb,
struct fib_rules_ops *ops)
{
int err = -EINVAL;
if (frh->src_len)
if (tb[FRA_SRC] == NULL ||
frh->src_len > (ops->addr_size * 8) ||
nla_len(tb[FRA_SRC]) != ops->addr_size)
goto errout;
if (frh->dst_len)
if (tb[FRA_DST] == NULL ||
frh->dst_len > (ops->addr_size * 8) ||
nla_len(tb[FRA_DST]) != ops->addr_size)
goto errout;
err = 0;
errout:
return err;
}
static int fib_nl_newrule(struct sk_buff *skb, struct nlmsghdr* nlh, void *arg)
{
struct fib_rule_hdr *frh = nlmsg_data(nlh);
struct fib_rules_ops *ops = NULL;
struct fib_rule *rule, *r, *last = NULL;
struct nlattr *tb[FRA_MAX+1];
int err = -EINVAL;
if (nlh->nlmsg_len < nlmsg_msg_size(sizeof(*frh)))
goto errout;
ops = lookup_rules_ops(frh->family);
if (ops == NULL) {
err = EAFNOSUPPORT;
goto errout;
}
err = nlmsg_parse(nlh, sizeof(*frh), tb, FRA_MAX, ops->policy);
if (err < 0)
goto errout;
err = validate_rulemsg(frh, tb, ops);
if (err < 0)
goto errout;
rule = kzalloc(ops->rule_size, GFP_KERNEL);
if (rule == NULL) {
err = -ENOMEM;
goto errout;
}
if (tb[FRA_PRIORITY])
rule->pref = nla_get_u32(tb[FRA_PRIORITY]);
if (tb[FRA_IFNAME]) {
struct net_device *dev;
rule->ifindex = -1;
nla_strlcpy(rule->ifname, tb[FRA_IFNAME], IFNAMSIZ);
dev = __dev_get_by_name(rule->ifname);
if (dev)
rule->ifindex = dev->ifindex;
}
if (tb[FRA_FWMARK]) {
rule->mark = nla_get_u32(tb[FRA_FWMARK]);
if (rule->mark)
/* compatibility: if the mark value is non-zero all bits
* are compared unless a mask is explicitly specified.
*/
rule->mark_mask = 0xFFFFFFFF;
}
if (tb[FRA_FWMASK])
rule->mark_mask = nla_get_u32(tb[FRA_FWMASK]);
rule->action = frh->action;
rule->flags = frh->flags;
rule->table = frh_get_table(frh, tb);
if (!rule->pref && ops->default_pref)
rule->pref = ops->default_pref();
err = ops->configure(rule, skb, nlh, frh, tb);
if (err < 0)
goto errout_free;
list_for_each_entry(r, ops->rules_list, list) {
if (r->pref > rule->pref)
break;
last = r;
}
fib_rule_get(rule);
if (last)
list_add_rcu(&rule->list, &last->list);
else
list_add_rcu(&rule->list, ops->rules_list);
notify_rule_change(RTM_NEWRULE, rule, ops, nlh, NETLINK_CB(skb).pid);
rules_ops_put(ops);
return 0;
errout_free:
kfree(rule);
errout:
rules_ops_put(ops);
return err;
}
static int fib_nl_delrule(struct sk_buff *skb, struct nlmsghdr* nlh, void *arg)
{
struct fib_rule_hdr *frh = nlmsg_data(nlh);
struct fib_rules_ops *ops = NULL;
struct fib_rule *rule;
struct nlattr *tb[FRA_MAX+1];
int err = -EINVAL;
if (nlh->nlmsg_len < nlmsg_msg_size(sizeof(*frh)))
goto errout;
ops = lookup_rules_ops(frh->family);
if (ops == NULL) {
err = EAFNOSUPPORT;
goto errout;
}
err = nlmsg_parse(nlh, sizeof(*frh), tb, FRA_MAX, ops->policy);
if (err < 0)
goto errout;
err = validate_rulemsg(frh, tb, ops);
if (err < 0)
goto errout;
list_for_each_entry(rule, ops->rules_list, list) {
if (frh->action && (frh->action != rule->action))
continue;
if (frh->table && (frh_get_table(frh, tb) != rule->table))
continue;
if (tb[FRA_PRIORITY] &&
(rule->pref != nla_get_u32(tb[FRA_PRIORITY])))
continue;
if (tb[FRA_IFNAME] &&
nla_strcmp(tb[FRA_IFNAME], rule->ifname))
continue;
if (tb[FRA_FWMARK] &&
(rule->mark != nla_get_u32(tb[FRA_FWMARK])))
continue;
if (tb[FRA_FWMASK] &&
(rule->mark_mask != nla_get_u32(tb[FRA_FWMASK])))
continue;
if (!ops->compare(rule, frh, tb))
continue;
if (rule->flags & FIB_RULE_PERMANENT) {
err = -EPERM;
goto errout;
}
list_del_rcu(&rule->list);
synchronize_rcu();
notify_rule_change(RTM_DELRULE, rule, ops, nlh,
NETLINK_CB(skb).pid);
fib_rule_put(rule);
rules_ops_put(ops);
return 0;
}
err = -ENOENT;
errout:
rules_ops_put(ops);
return err;
}
static inline size_t fib_rule_nlmsg_size(struct fib_rules_ops *ops,
struct fib_rule *rule)
{
size_t payload = NLMSG_ALIGN(sizeof(struct fib_rule_hdr))
+ nla_total_size(IFNAMSIZ) /* FRA_IFNAME */
+ nla_total_size(4) /* FRA_PRIORITY */
+ nla_total_size(4) /* FRA_TABLE */
+ nla_total_size(4) /* FRA_FWMARK */
+ nla_total_size(4); /* FRA_FWMASK */
if (ops->nlmsg_payload)
payload += ops->nlmsg_payload(rule);
return payload;
}
static int fib_nl_fill_rule(struct sk_buff *skb, struct fib_rule *rule,
u32 pid, u32 seq, int type, int flags,
struct fib_rules_ops *ops)
{
struct nlmsghdr *nlh;
struct fib_rule_hdr *frh;
nlh = nlmsg_put(skb, pid, seq, type, sizeof(*frh), flags);
if (nlh == NULL)
return -EMSGSIZE;
frh = nlmsg_data(nlh);
frh->table = rule->table;
NLA_PUT_U32(skb, FRA_TABLE, rule->table);
frh->res1 = 0;
frh->res2 = 0;
frh->action = rule->action;
frh->flags = rule->flags;
if (rule->ifname[0])
NLA_PUT_STRING(skb, FRA_IFNAME, rule->ifname);
if (rule->pref)
NLA_PUT_U32(skb, FRA_PRIORITY, rule->pref);
if (rule->mark)
NLA_PUT_U32(skb, FRA_FWMARK, rule->mark);
if (rule->mark_mask || rule->mark)
NLA_PUT_U32(skb, FRA_FWMASK, rule->mark_mask);
if (ops->fill(rule, skb, nlh, frh) < 0)
goto nla_put_failure;
return nlmsg_end(skb, nlh);
nla_put_failure:
nlmsg_cancel(skb, nlh);
return -EMSGSIZE;
}
static int dump_rules(struct sk_buff *skb, struct netlink_callback *cb,
struct fib_rules_ops *ops)
{
int idx = 0;
struct fib_rule *rule;
rcu_read_lock();
list_for_each_entry_rcu(rule, ops->rules_list, list) {
if (idx < cb->args[1])
goto skip;
if (fib_nl_fill_rule(skb, rule, NETLINK_CB(cb->skb).pid,
cb->nlh->nlmsg_seq, RTM_NEWRULE,
NLM_F_MULTI, ops) < 0)
break;
skip:
idx++;
}
rcu_read_unlock();
cb->args[1] = idx;
rules_ops_put(ops);
return skb->len;
}
static int fib_nl_dumprule(struct sk_buff *skb, struct netlink_callback *cb)
{
struct fib_rules_ops *ops;
int idx = 0, family;
family = rtnl_msg_family(cb->nlh);
if (family != AF_UNSPEC) {
/* Protocol specific dump request */
ops = lookup_rules_ops(family);
if (ops == NULL)
return -EAFNOSUPPORT;
return dump_rules(skb, cb, ops);
}
rcu_read_lock();
list_for_each_entry_rcu(ops, &rules_ops, list) {
if (idx < cb->args[0] || !try_module_get(ops->owner))
goto skip;
if (dump_rules(skb, cb, ops) < 0)
break;
cb->args[1] = 0;
skip:
idx++;
}
rcu_read_unlock();
cb->args[0] = idx;
return skb->len;
}
static void notify_rule_change(int event, struct fib_rule *rule,
struct fib_rules_ops *ops, struct nlmsghdr *nlh,
u32 pid)
{
struct sk_buff *skb;
int err = -ENOBUFS;
skb = nlmsg_new(fib_rule_nlmsg_size(ops, rule), GFP_KERNEL);
if (skb == NULL)
goto errout;
err = fib_nl_fill_rule(skb, rule, pid, nlh->nlmsg_seq, event, 0, ops);
if (err < 0) {
/* -EMSGSIZE implies BUG in fib_rule_nlmsg_size() */
WARN_ON(err == -EMSGSIZE);
kfree_skb(skb);
goto errout;
}
err = rtnl_notify(skb, pid, ops->nlgroup, nlh, GFP_KERNEL);
errout:
if (err < 0)
rtnl_set_sk_err(ops->nlgroup, err);
}
static void attach_rules(struct list_head *rules, struct net_device *dev)
{
struct fib_rule *rule;
list_for_each_entry(rule, rules, list) {
if (rule->ifindex == -1 &&
strcmp(dev->name, rule->ifname) == 0)
rule->ifindex = dev->ifindex;
}
}
static void detach_rules(struct list_head *rules, struct net_device *dev)
{
struct fib_rule *rule;
list_for_each_entry(rule, rules, list)
if (rule->ifindex == dev->ifindex)
rule->ifindex = -1;
}
static int fib_rules_event(struct notifier_block *this, unsigned long event,
void *ptr)
{
struct net_device *dev = ptr;
struct fib_rules_ops *ops;
ASSERT_RTNL();
rcu_read_lock();
switch (event) {
case NETDEV_REGISTER:
list_for_each_entry(ops, &rules_ops, list)
attach_rules(ops->rules_list, dev);
break;
case NETDEV_UNREGISTER:
list_for_each_entry(ops, &rules_ops, list)
detach_rules(ops->rules_list, dev);
break;
}
rcu_read_unlock();
return NOTIFY_DONE;
}
static struct notifier_block fib_rules_notifier = {
.notifier_call = fib_rules_event,
};
static int __init fib_rules_init(void)
{
rtnl_register(PF_UNSPEC, RTM_NEWRULE, fib_nl_newrule, NULL);
rtnl_register(PF_UNSPEC, RTM_DELRULE, fib_nl_delrule, NULL);
rtnl_register(PF_UNSPEC, RTM_GETRULE, NULL, fib_nl_dumprule);
return register_netdevice_notifier(&fib_rules_notifier);
}
subsys_initcall(fib_rules_init);