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  1. 25 5月, 2007 1 次提交
    • D
      [XFRM]: Allow packet drops during larval state resolution. · 14e50e57
      由 David S. Miller 提交于 
      The current IPSEC rule resolution behavior we have does not work for a
lot of people, even though technically it's an improvement from the
-EAGAIN buisness we had before.

Right now we'll block until the key manager resolves the route.  That
works for simple cases, but many folks would rather packets get
silently dropped until the key manager resolves the IPSEC rules.

We can't tell these folks to "set the socket non-blocking" because
they don't have control over the non-block setting of things like the
sockets used to resolve DNS deep inside of the resolver libraries in
libc.

With that in mind I coded up the patch below with some help from
Herbert Xu which provides packet-drop behavior during larval state
resolution, controllable via sysctl and off by default.

This lays the framework to either:

1) Make this default at some point or...

2) Move this logic into xfrm{4,6}_policy.c and implement the
   ARP-like resolution queue we've all been dreaming of.
   The idea would be to queue packets to the policy, then
   once the larval state is resolved by the key manager we
   re-resolve the route and push the packets out.  The
   packets would timeout if the rule didn't get resolved
   in a certain amount of time.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      14e50e57
  3. 26 4月, 2007 6 次提交
  5. 14 4月, 2007 1 次提交
  7. 07 4月, 2007 1 次提交
  9. 26 3月, 2007 1 次提交
    • D
      [IPV6]: Fix routing round-robin locking. · f11e6659
      由 David S. Miller 提交于 
      As per RFC2461, section 6.3.6, item #2, when no routers on the
matching list are known to be reachable or probably reachable we
do round robin on those available routes so that we make sure
to probe as many of them as possible to detect when one becomes
reachable faster.

Each routing table has a rwlock protecting the tree and the linked
list of routes at each leaf.  The round robin code executes during
lookup and thus with the rwlock taken as a reader.  A small local
spinlock tries to provide protection but this does not work at all
for two reasons:

1) The round-robin list manipulation, as coded, goes like this (with
   read lock held):

	walk routes finding head and tail

	spin_lock();
	rotate list using head and tail
	spin_unlock();

   While one thread is rotating the list, another thread can
   end up with stale values of head and tail and then proceed
   to corrupt the list when it gets the lock.  This ends up causing
   the OOPS in fib6_add() later onthat many people have been hitting.

2) All the other code paths that run with the rwlock held as
   a reader do not expect the list to change on them, they
   expect it to remain completely fixed while they hold the
   lock in that way.

So, simply stated, it is impossible to implement this correctly using
a manipulation of the list without violating the rwlock locking
semantics.

Reimplement using a per-fib6_node round-robin pointer.  This way we
don't need to manipulate the list at all, and since the round-robin
pointer can only ever point to real existing entries we don't need
to perform any locking on the changing of the round-robin pointer
itself.  We only need to reset the round-robin pointer to NULL when
the entry it is pointing to is removed.

The idea is from Thomas Graf and it is very similar to how this
was implemented before the advanced router selection code when in.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      f11e6659
  11. 23 3月, 2007 1 次提交
  13. 13 2月, 2007 1 次提交
  15. 11 2月, 2007 2 次提交
  17. 09 2月, 2007 2 次提交
  19. 24 1月, 2007 1 次提交
  21. 14 12月, 2006 1 次提交
  23. 03 12月, 2006 9 次提交
  25. 22 11月, 2006 3 次提交
  27. 19 10月, 2006 4 次提交
  29. 16 10月, 2006 1 次提交
  31. 23 9月, 2006 5 次提交