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  1. 02 5月, 2019 3 次提交
    • F
      netfilter: nf_tables: split set destruction in deactivate and destroy phase · 3dbba8eb
      由 Florian Westphal 提交于 
      [ Upstream commit cd5125d8f51882279f50506bb9c7e5e89dc9bef3 ]

Splits unbind_set into destroy_set and unbinding operation.

Unbinding removes set from lists (so new transaction would not
find it anymore) but keeps memory allocated (so packet path continues
to work).

Rebind function is added to allow unrolling in case transaction
that wants to remove set is aborted.

Destroy function is added to free the memory, but this could occur
outside of transaction in the future.
Signed-off-by: NFlorian Westphal <fw@strlen.de>
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: NSasha Levin <sashal@kernel.org>
      3dbba8eb
    • F
      netfilter: nft_compat: make lists per netns · 7693bae6
      由 Florian Westphal 提交于 
      [ Upstream commit cf52572ebbd7189a1966c2b5fc34b97078cd1dce ]

There are two problems with nft_compat since the netlink config
plane uses a per-netns mutex:

1. Concurrent add/del accesses to the same list
2. accesses to a list element after it has been free'd already.

This patch fixes the first problem.

Freeing occurs from a work queue, after transaction mutexes have been
released, i.e., it still possible for a new transaction (even from
same net ns) to find the to-be-deleted expression in the list.

The ->destroy functions are not allowed to have any such side effects,
i.e. the list_del() in the destroy function is not allowed.

This part of the problem is solved in the next patch.
I tried to make this work by serializing list access via mutex
and by moving list_del() to a deactivate callback, but
Taehee spotted following race on this approach:

  NET #0                          NET #1
   >select_ops()
   ->init()
                                   ->select_ops()
   ->deactivate()
   ->destroy()
      nft_xt_put()
       kfree_rcu(xt, rcu_head);
                                   ->init() <-- use-after-free occurred.

Unfortunately, we can't increment reference count in
select_ops(), because we can't undo the refcount increase in
case a different expression fails in the same batch.

(The destroy hook will only be called in case the expression
 was initialized successfully).

Fixes: f102d66b ("netfilter: nf_tables: use dedicated mutex to guard transactions")
Reported-by: NTaehee Yoo <ap420073@gmail.com>
Signed-off-by: NFlorian Westphal <fw@strlen.de>
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: NSasha Levin <sashal@kernel.org>
      7693bae6
    • F
      netfilter: nft_compat: use refcnt_t type for nft_xt reference count · db99f122
      由 Florian Westphal 提交于 
      [ Upstream commit 12c44aba6618b7f6c437076e5722237190f6cd5f ]

Using standard integer type was fine while all operations on it were
guarded by the nftnl subsys mutex.

This isn't true anymore:
1. transactions are guarded only by a pernet mutex, so concurrent
   rule manipulation in different netns is racy
2. the ->destroy hook runs from a work queue after the transaction
   mutex has been released already.

cpu0                           cpu1 (net 1)        cpu2 (net 2)
 kworker
    nft_compat->destroy        nft_compat->init    nft_compat->init
      if (--nft_xt->ref == 0)   nft_xt->ref++        nft_xt->ref++

Switch to refcount_t.  Doing this however only fixes a minor aspect,
nft_compat also performs linked-list operations in an unsafe way.

This is addressed in the next two patches.

Fixes: f102d66b ("netfilter: nf_tables: use dedicated mutex to guard transactions")
Fixes: 0935d5588400 ("netfilter: nf_tables: asynchronous release")
Reported-by: NTaehee Yoo <ap420073@gmail.com>
Signed-off-by: NFlorian Westphal <fw@strlen.de>
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: NSasha Levin <sashal@kernel.org>
      db99f122
  3. 27 4月, 2019 37 次提交