From 8a226b2cfa776db6011fc84b71578513161cd3d3 Mon Sep 17 00:00:00 2001 From: Jiri Benc Date: Thu, 1 Aug 2013 10:41:28 +0200 Subject: ipv6: prevent race between address creation and removal 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 Signed-off-by: Jiri Pirko Signed-off-by: David S. Miller --- net/ipv6/addrconf.c | 31 +++++++++++++++---------------- 1 file changed, 15 insertions(+), 16 deletions(-) (limited to 'net') diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c index a0ce957fb671..da4241c8c7da 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); -- cgit v1.2.3