1. 24 Jul, 2018 2 commits
    • Manikanta Pubbisetty's avatar
      mac80211: restrict delayed tailroom needed decrement · 133bf90d
      Manikanta Pubbisetty authored
      As explained in ieee80211_delayed_tailroom_dec(), during roam,
      keys of the old AP will be destroyed and new keys will be
      installed. Deletion of the old key causes
      crypto_tx_tailroom_needed_cnt to go from 1 to 0 and the new key
      installation causes a transition from 0 to 1.
      
      Whenever crypto_tx_tailroom_needed_cnt transitions from 0 to 1,
      we invoke synchronize_net(); the reason for doing this is to avoid
      a race in the TX path as explained in increment_tailroom_need_count().
      This synchronize_net() operation can be slow and can affect the station
      roam time. To avoid this, decrementing the crypto_tx_tailroom_needed_cnt
      is delayed for a while so that upon installation of new key the
      transition would be from 1 to 2 instead of 0 to 1 and thereby
      improving the roam time.
      
      This is all correct for a STA iftype, but deferring the tailroom_needed
      decrement for other iftypes may be unnecessary.
      
      For example, let's consider the case of a 4-addr client connecting to
      an AP for which AP_VLAN interface is also created, let the initial
      value for tailroom_needed on the AP be 1.
      
      * 4-addr client connects to the AP (AP: tailroom_needed = 1)
      * AP will clear old keys, delay decrement of tailroom_needed count
      * AP_VLAN is created, it takes the tailroom count from master
        (AP_VLAN: tailroom_needed = 1, AP: tailroom_needed = 1)
      * Install new key for the station, assume key is plumbed in the HW,
        there won't be any change in tailroom_needed count on AP iface
      * Delayed decrement of tailroom_needed count on AP
        (AP: tailroom_needed = 0, AP_VLAN: tailroom_needed = 1)
      
      Because of the delayed decrement on AP iface, tailroom_needed count goes
      out of sync between AP(master iface) and AP_VLAN(slave iface) and
      there would be unnecessary tailroom created for the packets going
      through AP_VLAN iface.
      
      Also, WARN_ONs were observed while trying to bring down the AP_VLAN
      interface:
      (warn_slowpath_common) (warn_slowpath_null+0x18/0x20)
      (warn_slowpath_null) (ieee80211_free_keys+0x114/0x1e4)
      (ieee80211_free_keys) (ieee80211_del_virtual_monitor+0x51c/0x850)
      (ieee80211_del_virtual_monitor) (ieee80211_stop+0x30/0x3c)
      (ieee80211_stop) (__dev_close_many+0x94/0xb8)
      (__dev_close_many) (dev_close_many+0x5c/0xc8)
      
      Restricting delayed decrement to station interface alone fixes the problem
      and it makes sense to do so because delayed decrement is done to improve
      roam time which is applicable only for client devices.
      Signed-off-by: default avatarManikanta Pubbisetty <mpubbise@codeaurora.org>
      Signed-off-by: default avatarJohannes Berg <johannes.berg@intel.com>
      133bf90d
    • Kees Cook's avatar
      wireless/lib80211: Convert from ahash to shash · d17504b1
      Kees Cook authored
      In preparing to remove all stack VLA usage from the kernel[1], this
      removes the discouraged use of AHASH_REQUEST_ON_STACK in favor of
      the smaller SHASH_DESC_ON_STACK by converting from ahash-wrapped-shash
      to direct shash. The stack allocation will be made a fixed size in a
      later patch to the crypto subsystem.
      
      [1] https://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qPXydAacU1RqZWA@mail.gmail.comSigned-off-by: default avatarKees Cook <keescook@chromium.org>
      Signed-off-by: default avatarJohannes Berg <johannes.berg@intel.com>
      d17504b1
  2. 09 Jul, 2018 2 commits
  3. 08 Jul, 2018 26 commits
  4. 07 Jul, 2018 10 commits