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Merge branch 'ipv6-addrlabel-avoid-dirtying-ip6addrlbl_entry'

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Eric Dumazet says:

====================
ipv6: addrlabel: avoid dirtying ip6addrlbl_entry

The refcount on ip6addrlbl_entry is only used to make sure ip6addrlbl_entry
does not disappear while ip6addrlbl_get() is allocating an skb.

We can instead allocate skb first, then use RCU, so that we no longer need
to refcount these structures.
====================

Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
David S. Miller 2017-10-09 10:47:30 -07:00
commit 2e997d8b12
1 changed files with 17 additions and 52 deletions
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69
net/ipv6/addrlabel.c
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@ -18,7 +18,6 @@
#include <linux/if_addrlabel.h> #include <linux/if_addrlabel.h>
#include <linux/netlink.h> #include <linux/netlink.h>
#include <linux/rtnetlink.h> #include <linux/rtnetlink.h>
#include <linux/refcount.h>
#if 0 #if 0
#define ADDRLABEL(x...) printk(x) #define ADDRLABEL(x...) printk(x)
@ -36,7 +35,6 @@ struct ip6addrlbl_entry {
int addrtype; int addrtype;
u32 label; u32 label;
struct hlist_node list; struct hlist_node list;
refcount_t refcnt;
struct rcu_head rcu; struct rcu_head rcu;
}; };
@ -111,28 +109,6 @@ static const __net_initconst struct ip6addrlbl_init_table
} }
}; };
/* Object management */
static inline void ip6addrlbl_free(struct ip6addrlbl_entry *p)
{
kfree(p);
}
static void ip6addrlbl_free_rcu(struct rcu_head *h)
{
ip6addrlbl_free(container_of(h, struct ip6addrlbl_entry, rcu));
}
static bool ip6addrlbl_hold(struct ip6addrlbl_entry *p)
{
return refcount_inc_not_zero(&p->refcnt);
}
static inline void ip6addrlbl_put(struct ip6addrlbl_entry *p)
{
if (refcount_dec_and_test(&p->refcnt))
call_rcu(&p->rcu, ip6addrlbl_free_rcu);
}
/* Find label */ /* Find label */
static bool __ip6addrlbl_match(const struct ip6addrlbl_entry *p, static bool __ip6addrlbl_match(const struct ip6addrlbl_entry *p,
const struct in6_addr *addr, const struct in6_addr *addr,
@ -219,7 +195,6 @@ static struct ip6addrlbl_entry *ip6addrlbl_alloc(const struct in6_addr *prefix,
newp->addrtype = addrtype; newp->addrtype = addrtype;
newp->label = label; newp->label = label;
INIT_HLIST_NODE(&newp->list); INIT_HLIST_NODE(&newp->list);
refcount_set(&newp->refcnt, 1);
return newp; return newp;
} }
@ -243,7 +218,7 @@ static int __ip6addrlbl_add(struct net *net, struct ip6addrlbl_entry *newp,
goto out; goto out;
} }
hlist_replace_rcu(&p->list, &newp->list); hlist_replace_rcu(&p->list, &newp->list);
ip6addrlbl_put(p); kfree_rcu(p, rcu);
goto out; goto out;
} else if ((p->prefixlen == newp->prefixlen && !p->ifindex) || } else if ((p->prefixlen == newp->prefixlen && !p->ifindex) ||
(p->prefixlen < newp->prefixlen)) { (p->prefixlen < newp->prefixlen)) {
@ -281,7 +256,7 @@ static int ip6addrlbl_add(struct net *net,
ret = __ip6addrlbl_add(net, newp, replace); ret = __ip6addrlbl_add(net, newp, replace);
spin_unlock(&net->ipv6.ip6addrlbl_table.lock); spin_unlock(&net->ipv6.ip6addrlbl_table.lock);
if (ret) if (ret)
ip6addrlbl_free(newp); kfree(newp);
return ret; return ret;
} }
@ -302,7 +277,7 @@ static int __ip6addrlbl_del(struct net *net,
p->ifindex == ifindex && p->ifindex == ifindex &&
ipv6_addr_equal(&p->prefix, prefix)) { ipv6_addr_equal(&p->prefix, prefix)) {
hlist_del_rcu(&p->list); hlist_del_rcu(&p->list);
ip6addrlbl_put(p); kfree_rcu(p, rcu);
ret = 0; ret = 0;
break; break;
} }
@ -360,7 +335,7 @@ static void __net_exit ip6addrlbl_net_exit(struct net *net)
spin_lock(&net->ipv6.ip6addrlbl_table.lock); spin_lock(&net->ipv6.ip6addrlbl_table.lock);
hlist_for_each_entry_safe(p, n, &net->ipv6.ip6addrlbl_table.head, list) { hlist_for_each_entry_safe(p, n, &net->ipv6.ip6addrlbl_table.head, list) {
hlist_del_rcu(&p->list); hlist_del_rcu(&p->list);
ip6addrlbl_put(p); kfree_rcu(p, rcu);
} }
spin_unlock(&net->ipv6.ip6addrlbl_table.lock); spin_unlock(&net->ipv6.ip6addrlbl_table.lock);
} }
@ -546,38 +521,28 @@ static int ip6addrlbl_get(struct sk_buff *in_skb, struct nlmsghdr *nlh,
return -EINVAL; return -EINVAL;
addr = nla_data(tb[IFAL_ADDRESS]); addr = nla_data(tb[IFAL_ADDRESS]);
skb = nlmsg_new(ip6addrlbl_msgsize(), GFP_KERNEL);
if (!skb)
return -ENOBUFS;
err = -ESRCH;
rcu_read_lock(); rcu_read_lock();
p = __ipv6_addr_label(net, addr, ipv6_addr_type(addr), ifal->ifal_index); p = __ipv6_addr_label(net, addr, ipv6_addr_type(addr), ifal->ifal_index);
if (p && !ip6addrlbl_hold(p))
p = NULL;
lseq = net->ipv6.ip6addrlbl_table.seq; lseq = net->ipv6.ip6addrlbl_table.seq;
if (p)
err = ip6addrlbl_fill(skb, p, lseq,
NETLINK_CB(in_skb).portid,
nlh->nlmsg_seq,
RTM_NEWADDRLABEL, 0);
rcu_read_unlock(); rcu_read_unlock();
if (!p) {
err = -ESRCH;
goto out;
}
skb = nlmsg_new(ip6addrlbl_msgsize(), GFP_KERNEL);
if (!skb) {
ip6addrlbl_put(p);
return -ENOBUFS;
}
err = ip6addrlbl_fill(skb, p, lseq,
NETLINK_CB(in_skb).portid, nlh->nlmsg_seq,
RTM_NEWADDRLABEL, 0);
ip6addrlbl_put(p);
if (err < 0) { if (err < 0) {
WARN_ON(err == -EMSGSIZE); WARN_ON(err == -EMSGSIZE);
kfree_skb(skb); kfree_skb(skb);
goto out; } else {
err = rtnl_unicast(skb, net, NETLINK_CB(in_skb).portid);
} }
err = rtnl_unicast(skb, net, NETLINK_CB(in_skb).portid);
out:
return err; return err;
} }