linux/net/core/fib_rules.c
Pablo Neira Ayuso 1ce85fe402 netlink: change nlmsg_notify() return value logic
This patch changes the return value of nlmsg_notify() as follows:

If NETLINK_BROADCAST_ERROR is set by any of the listeners and
an error in the delivery happened, return the broadcast error;
else if there are no listeners apart from the socket that
requested a change with the echo flag, return the result of the
unicast notification. Thus, with this patch, the unicast
notification is handled in the same way of a broadcast listener
that has set the NETLINK_BROADCAST_ERROR socket flag.

This patch is useful in case that the caller of nlmsg_notify()
wants to know the result of the delivery of a netlink notification
(including the broadcast delivery) and take any action in case
that the delivery failed. For example, ctnetlink can drop packets
if the event delivery failed to provide reliable logging and
state-synchronization at the cost of dropping packets.

This patch also modifies the rtnetlink code to ignore the return
value of rtnl_notify() in all callers. The function rtnl_notify()
(before this patch) returned the error of the unicast notification
which makes rtnl_set_sk_err() reports errors to all listeners. This
is not of any help since the origin of the change (the socket that
requested the echoing) notices the ENOBUFS error if the notification
fails and should resync itself.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Acked-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
2009-02-24 23:18:28 -08:00

688 lines
15 KiB
C

/*
* 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/net_namespace.h>
#include <net/sock.h>
#include <net/fib_rules.h>
int fib_default_rule_add(struct fib_rules_ops *ops,
u32 pref, u32 table, u32 flags)
{
struct fib_rule *r;
r = kzalloc(ops->rule_size, GFP_KERNEL);
if (r == NULL)
return -ENOMEM;
atomic_set(&r->refcnt, 1);
r->action = FR_ACT_TO_TBL;
r->pref = pref;
r->table = table;
r->flags = flags;
r->fr_net = hold_net(ops->fro_net);
/* The lock is not required here, the list in unreacheable
* at the moment this function is called */
list_add_tail(&r->list, &ops->rules_list);
return 0;
}
EXPORT_SYMBOL(fib_default_rule_add);
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(struct net *net, int family)
{
struct fib_rules_ops *ops;
rcu_read_lock();
list_for_each_entry_rcu(ops, &net->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);
}
static void flush_route_cache(struct fib_rules_ops *ops)
{
if (ops->flush_cache)
ops->flush_cache(ops);
}
int fib_rules_register(struct fib_rules_ops *ops)
{
int err = -EEXIST;
struct fib_rules_ops *o;
struct net *net;
net = ops->fro_net;
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(&net->rules_mod_lock);
list_for_each_entry(o, &net->rules_ops, list)
if (ops->family == o->family)
goto errout;
hold_net(net);
list_add_tail_rcu(&ops->list, &net->rules_ops);
err = 0;
errout:
spin_unlock(&net->rules_mod_lock);
return err;
}
EXPORT_SYMBOL_GPL(fib_rules_register);
void fib_rules_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);
}
}
EXPORT_SYMBOL_GPL(fib_rules_cleanup_ops);
void fib_rules_unregister(struct fib_rules_ops *ops)
{
struct net *net = ops->fro_net;
spin_lock(&net->rules_mod_lock);
list_del_rcu(&ops->list);
fib_rules_cleanup_ops(ops);
spin_unlock(&net->rules_mod_lock);
synchronize_rcu();
release_net(net);
}
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) {
jumped:
if (!fib_rule_match(rule, ops, fl, flags))
continue;
if (rule->action == FR_ACT_GOTO) {
struct fib_rule *target;
target = rcu_dereference(rule->ctarget);
if (target == NULL) {
continue;
} else {
rule = target;
goto jumped;
}
} else if (rule->action == FR_ACT_NOP)
continue;
else
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 net *net = sock_net(skb->sk);
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, unresolved = 0;
if (nlh->nlmsg_len < nlmsg_msg_size(sizeof(*frh)))
goto errout;
ops = lookup_rules_ops(net, 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;
}
rule->fr_net = hold_net(net);
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(net, 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(ops);
err = -EINVAL;
if (tb[FRA_GOTO]) {
if (rule->action != FR_ACT_GOTO)
goto errout_free;
rule->target = nla_get_u32(tb[FRA_GOTO]);
/* Backward jumps are prohibited to avoid endless loops */
if (rule->target <= rule->pref)
goto errout_free;
list_for_each_entry(r, &ops->rules_list, list) {
if (r->pref == rule->target) {
rule->ctarget = r;
break;
}
}
if (rule->ctarget == NULL)
unresolved = 1;
} else if (rule->action == FR_ACT_GOTO)
goto errout_free;
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 (ops->unresolved_rules) {
/*
* There are unresolved goto rules in the list, check if
* any of them are pointing to this new rule.
*/
list_for_each_entry(r, &ops->rules_list, list) {
if (r->action == FR_ACT_GOTO &&
r->target == rule->pref) {
BUG_ON(r->ctarget != NULL);
rcu_assign_pointer(r->ctarget, rule);
if (--ops->unresolved_rules == 0)
break;
}
}
}
if (rule->action == FR_ACT_GOTO)
ops->nr_goto_rules++;
if (unresolved)
ops->unresolved_rules++;
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);
flush_route_cache(ops);
rules_ops_put(ops);
return 0;
errout_free:
release_net(rule->fr_net);
kfree(rule);
errout:
rules_ops_put(ops);
return err;
}
static int fib_nl_delrule(struct sk_buff *skb, struct nlmsghdr* nlh, void *arg)
{
struct net *net = sock_net(skb->sk);
struct fib_rule_hdr *frh = nlmsg_data(nlh);
struct fib_rules_ops *ops = NULL;
struct fib_rule *rule, *tmp;
struct nlattr *tb[FRA_MAX+1];
int err = -EINVAL;
if (nlh->nlmsg_len < nlmsg_msg_size(sizeof(*frh)))
goto errout;
ops = lookup_rules_ops(net, 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);
if (rule->action == FR_ACT_GOTO)
ops->nr_goto_rules--;
/*
* Check if this rule is a target to any of them. If so,
* disable them. As this operation is eventually very
* expensive, it is only performed if goto rules have
* actually been added.
*/
if (ops->nr_goto_rules > 0) {
list_for_each_entry(tmp, &ops->rules_list, list) {
if (tmp->ctarget == rule) {
rcu_assign_pointer(tmp->ctarget, NULL);
ops->unresolved_rules++;
}
}
}
synchronize_rcu();
notify_rule_change(RTM_DELRULE, rule, ops, nlh,
NETLINK_CB(skb).pid);
fib_rule_put(rule);
flush_route_cache(ops);
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->action == FR_ACT_GOTO && rule->ctarget == NULL)
frh->flags |= FIB_RULE_UNRESOLVED;
if (rule->ifname[0]) {
NLA_PUT_STRING(skb, FRA_IFNAME, rule->ifname);
if (rule->ifindex == -1)
frh->flags |= FIB_RULE_DEV_DETACHED;
}
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 (rule->target)
NLA_PUT_U32(skb, FRA_GOTO, rule->target);
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;
list_for_each_entry(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++;
}
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 net *net = sock_net(skb->sk);
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(net, family);
if (ops == NULL)
return -EAFNOSUPPORT;
return dump_rules(skb, cb, ops);
}
rcu_read_lock();
list_for_each_entry_rcu(ops, &net->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 net *net;
struct sk_buff *skb;
int err = -ENOBUFS;
net = ops->fro_net;
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;
}
rtnl_notify(skb, net, pid, ops->nlgroup, nlh, GFP_KERNEL);
return;
errout:
if (err < 0)
rtnl_set_sk_err(net, 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 net *net = dev_net(dev);
struct fib_rules_ops *ops;
ASSERT_RTNL();
rcu_read_lock();
switch (event) {
case NETDEV_REGISTER:
list_for_each_entry(ops, &net->rules_ops, list)
attach_rules(&ops->rules_list, dev);
break;
case NETDEV_UNREGISTER:
list_for_each_entry(ops, &net->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 fib_rules_net_init(struct net *net)
{
INIT_LIST_HEAD(&net->rules_ops);
spin_lock_init(&net->rules_mod_lock);
return 0;
}
static struct pernet_operations fib_rules_net_ops = {
.init = fib_rules_net_init,
};
static int __init fib_rules_init(void)
{
int err;
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);
err = register_pernet_subsys(&fib_rules_net_ops);
if (err < 0)
goto fail;
err = register_netdevice_notifier(&fib_rules_notifier);
if (err < 0)
goto fail_unregister;
return 0;
fail_unregister:
unregister_pernet_subsys(&fib_rules_net_ops);
fail:
rtnl_unregister(PF_UNSPEC, RTM_NEWRULE);
rtnl_unregister(PF_UNSPEC, RTM_DELRULE);
rtnl_unregister(PF_UNSPEC, RTM_GETRULE);
return err;
}
subsys_initcall(fib_rules_init);