From: Sam Edwards cfsworks@gmail.com
[ Upstream commit 778964f2fdf05e5d2e6ca9bc3f450b3db454ba9c ]
The addrconf_verify_rtnl() function uses a big if/elseif/elseif/... block to categorize each address by what type of attention it needs. An about-to-expire (RFC 4941) temporary address is one such category, but the previous elseif branch catches addresses that have already run out their prefered_lft. This means that if addrconf_verify_rtnl() fails to run in the necessary time window (i.e. REGEN_ADVANCE time units before the end of the prefered_lft), the temporary address will never be regenerated, and no temporary addresses will be available until each one's valid_lft runs out and manage_tempaddrs() begins anew.
Fix this by moving the entire temporary address regeneration case out of that block. That block is supposed to implement the "destructive" part of an address's lifecycle, and regenerating a fresh temporary address is not, semantically speaking, actually tied to any particular lifecycle stage. The age test is also changed from `age >= prefered_lft - regen_advance` to `age + regen_advance >= prefered_lft` instead, to ensure no underflow occurs if the system administrator increases the regen_advance to a value greater than the already-set prefered_lft.
Note that this does not fix the problem of addrconf_verify_rtnl() sometimes not running in time, resulting in the race condition described in RFC 4941 section 3.4 - it only ensures that the address is regenerated. Fixing THAT problem may require either using jiffies instead of seconds for all time arithmetic here, or always rounding up when regen_advance is converted to seconds.
Signed-off-by: Sam Edwards CFSworks@gmail.com Link: https://lore.kernel.org/r/20220623181103.7033-1-CFSworks@gmail.com Signed-off-by: Paolo Abeni pabeni@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org --- net/ipv6/addrconf.c | 62 ++++++++++++++++++++++++--------------------- 1 file changed, 33 insertions(+), 29 deletions(-)
diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c index 05317e6f48f8..e11ae0327731 100644 --- a/net/ipv6/addrconf.c +++ b/net/ipv6/addrconf.c @@ -4513,6 +4513,39 @@ static void addrconf_verify_rtnl(void) /* We try to batch several events at once. */ age = (now - ifp->tstamp + ADDRCONF_TIMER_FUZZ_MINUS) / HZ;
+ if ((ifp->flags&IFA_F_TEMPORARY) && + !(ifp->flags&IFA_F_TENTATIVE) && + ifp->prefered_lft != INFINITY_LIFE_TIME && + !ifp->regen_count && ifp->ifpub) { + /* This is a non-regenerated temporary addr. */ + + unsigned long regen_advance = ifp->idev->cnf.regen_max_retry * + ifp->idev->cnf.dad_transmits * + max(NEIGH_VAR(ifp->idev->nd_parms, RETRANS_TIME), HZ/100) / HZ; + + if (age + regen_advance >= ifp->prefered_lft) { + struct inet6_ifaddr *ifpub = ifp->ifpub; + if (time_before(ifp->tstamp + ifp->prefered_lft * HZ, next)) + next = ifp->tstamp + ifp->prefered_lft * HZ; + + ifp->regen_count++; + in6_ifa_hold(ifp); + in6_ifa_hold(ifpub); + spin_unlock(&ifp->lock); + + spin_lock(&ifpub->lock); + ifpub->regen_count = 0; + spin_unlock(&ifpub->lock); + rcu_read_unlock_bh(); + ipv6_create_tempaddr(ifpub, true); + in6_ifa_put(ifpub); + in6_ifa_put(ifp); + rcu_read_lock_bh(); + goto restart; + } else if (time_before(ifp->tstamp + ifp->prefered_lft * HZ - regen_advance * HZ, next)) + next = ifp->tstamp + ifp->prefered_lft * HZ - regen_advance * HZ; + } + if (ifp->valid_lft != INFINITY_LIFE_TIME && age >= ifp->valid_lft) { spin_unlock(&ifp->lock); @@ -4544,35 +4577,6 @@ static void addrconf_verify_rtnl(void) in6_ifa_put(ifp); goto restart; } - } else if ((ifp->flags&IFA_F_TEMPORARY) && - !(ifp->flags&IFA_F_TENTATIVE)) { - unsigned long regen_advance = ifp->idev->cnf.regen_max_retry * - ifp->idev->cnf.dad_transmits * - max(NEIGH_VAR(ifp->idev->nd_parms, RETRANS_TIME), HZ/100) / HZ; - - if (age >= ifp->prefered_lft - regen_advance) { - struct inet6_ifaddr *ifpub = ifp->ifpub; - if (time_before(ifp->tstamp + ifp->prefered_lft * HZ, next)) - next = ifp->tstamp + ifp->prefered_lft * HZ; - if (!ifp->regen_count && ifpub) { - ifp->regen_count++; - in6_ifa_hold(ifp); - in6_ifa_hold(ifpub); - spin_unlock(&ifp->lock); - - spin_lock(&ifpub->lock); - ifpub->regen_count = 0; - spin_unlock(&ifpub->lock); - rcu_read_unlock_bh(); - ipv6_create_tempaddr(ifpub, true); - in6_ifa_put(ifpub); - in6_ifa_put(ifp); - rcu_read_lock_bh(); - goto restart; - } - } else if (time_before(ifp->tstamp + ifp->prefered_lft * HZ - regen_advance * HZ, next)) - next = ifp->tstamp + ifp->prefered_lft * HZ - regen_advance * HZ; - spin_unlock(&ifp->lock); } else { /* ifp->prefered_lft <= ifp->valid_lft */ if (time_before(ifp->tstamp + ifp->prefered_lft * HZ, next))