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Date: Thu, 1 Aug 2013 10:41:28 +0200
From: Jiri Pirko <jiri@...nulli.us>
To: netdev@...r.kernel.org
Cc: davem@...emloft.net, jbenc@...hat.com, kuznet@....inr.ac.ru,
jmorris@...ei.org, yoshfuji@...ux-ipv6.org, kaber@...sh.net
Subject: [patch net 2/2] ipv6: prevent race between address creation and removal
From: Jiri Benc <jbenc@...hat.com>
There's a race in IPv6 automatic addess assingment. 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@...hat.com>
Signed-off-by: Jiri Pirko <jiri@...nulli.us>
---
net/ipv6/addrconf.c | 31 +++++++++++++++----------------
1 file changed, 15 insertions(+), 16 deletions(-)
diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index a0ce957..da4241c 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -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);
--
1.7.11.7
--
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