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ipv6: prevent race between address creation and removal

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There's a race in IPv6 automatic addess assignment. The address is created
with zero lifetime when it's added to various address lists. Before it gets
assigned the correct lifetime, there's a window where a new address may be
configured. This causes the semi-initiated address to be deleted in
addrconf_verify.

This was discovered as a reference leak caused by concurrent run of
__ipv6_ifa_notify for both RTM_NEWADDR and RTM_DELADDR with the same
address.

Fix this by setting the lifetime before the address is added to
inet6_addr_lst.

A few notes:

1. In addrconf_prefix_rcv, by setting update_lft to zero, the
   if (update_lft) { ... } condition is no longer executed for newly
   created addresses. This is okay, as the ifp fields are set in
   ipv6_add_addr now and ipv6_ifa_notify is called (and has been called)
   through addrconf_dad_start.

2. The removal of the whole block under ifp->lock in inet6_addr_add is okay,
   too, as tstamp is initialized to jiffies in ipv6_add_addr.

Signed-off-by: Jiri Benc <jbenc@redhat.com>
Signed-off-by: Jiri Pirko <jiri@resnulli.us>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Jiri Benc 2013-08-01 10:41:28 +02:00 committed by David S. Miller
parent 3f8f52982a
commit 8a226b2cfa
1 changed files with 15 additions and 16 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

31
net/ipv6/addrconf.c
View File

@ -815,7 +815,7 @@ static u32 inet6_addr_hash(const struct in6_addr *addr)
static struct inet6_ifaddr *
ipv6_add_addr(struct inet6_dev *idev, const struct in6_addr *addr,
const struct in6_addr *peer_addr, int pfxlen,
int scope, u32 flags)
int scope, u32 flags, u32 valid_lft, u32 prefered_lft)
{
struct inet6_ifaddr *ifa = NULL;
struct rt6_info *rt;
@ -875,6 +875,8 @@ ipv6_add_addr(struct inet6_dev *idev, const struct in6_addr *addr,
ifa->scope = scope;
ifa->prefix_len = pfxlen;
ifa->flags = flags | IFA_F_TENTATIVE;
ifa->valid_lft = valid_lft;
ifa->prefered_lft = prefered_lft;
ifa->cstamp = ifa->tstamp = jiffies;
ifa->tokenized = false;
@ -1127,7 +1129,8 @@ retry:
ift = !max_addresses ||
ipv6_count_addresses(idev) < max_addresses ?
ipv6_add_addr(idev, &addr, NULL, tmp_plen,
ipv6_addr_scope(&addr), addr_flags) : NULL;
ipv6_addr_scope(&addr), addr_flags,
tmp_valid_lft, tmp_prefered_lft) : NULL;
if (IS_ERR_OR_NULL(ift)) {
in6_ifa_put(ifp);
in6_dev_put(idev);
@ -1139,8 +1142,6 @@ retry:
spin_lock_bh(&ift->lock);
ift->ifpub = ifp;
ift->valid_lft = tmp_valid_lft;
ift->prefered_lft = tmp_prefered_lft;
ift->cstamp = now;
ift->tstamp = tmp_tstamp;
spin_unlock_bh(&ift->lock);
@ -2185,14 +2186,16 @@ ok:
ifp = ipv6_add_addr(in6_dev, &addr, NULL,
pinfo->prefix_len,
addr_type&IPV6_ADDR_SCOPE_MASK,
addr_flags);
addr_flags, valid_lft,
prefered_lft);
if (IS_ERR_OR_NULL(ifp)) {
in6_dev_put(in6_dev);
return;
}
update_lft = create = 1;
update_lft = 0;
create = 1;
ifp->cstamp = jiffies;
ifp->tokenized = tokenized;
addrconf_dad_start(ifp);
@ -2213,7 +2216,7 @@ ok:
stored_lft = ifp->valid_lft - (now - ifp->tstamp) / HZ;
else
stored_lft = 0;
if (!update_lft && stored_lft) {
if (!update_lft && !create && stored_lft) {
if (valid_lft > MIN_VALID_LIFETIME ||
valid_lft > stored_lft)
update_lft = 1;
@ -2459,15 +2462,10 @@ static int inet6_addr_add(struct net *net, int ifindex, const struct in6_addr *p
prefered_lft = timeout;
}
ifp = ipv6_add_addr(idev, pfx, peer_pfx, plen, scope, ifa_flags);
ifp = ipv6_add_addr(idev, pfx, peer_pfx, plen, scope, ifa_flags,
valid_lft, prefered_lft);
if (!IS_ERR(ifp)) {
spin_lock_bh(&ifp->lock);
ifp->valid_lft = valid_lft;
ifp->prefered_lft = prefered_lft;
ifp->tstamp = jiffies;
spin_unlock_bh(&ifp->lock);
addrconf_prefix_route(&ifp->addr, ifp->prefix_len, dev,
expires, flags);
/*
@ -2559,7 +2557,8 @@ static void add_addr(struct inet6_dev *idev, const struct in6_addr *addr,
{
struct inet6_ifaddr *ifp;
ifp = ipv6_add_addr(idev, addr, NULL, plen, scope, IFA_F_PERMANENT);
ifp = ipv6_add_addr(idev, addr, NULL, plen,
scope, IFA_F_PERMANENT, 0, 0);
if (!IS_ERR(ifp)) {
spin_lock_bh(&ifp->lock);
ifp->flags &= ~IFA_F_TENTATIVE;
@ -2685,7 +2684,7 @@ static void addrconf_add_linklocal(struct inet6_dev *idev, const struct in6_addr
#endif
ifp = ipv6_add_addr(idev, addr, NULL, 64, IFA_LINK, addr_flags);
ifp = ipv6_add_addr(idev, addr, NULL, 64, IFA_LINK, addr_flags, 0, 0);
if (!IS_ERR(ifp)) {
addrconf_prefix_route(&ifp->addr, ifp->prefix_len, idev->dev, 0, 0);
addrconf_dad_start(ifp);