act_mirred: use the backlog for nested calls to mirred ingress
[ Upstream commit ca22da2fbd693b54dc8e3b7b54ccc9f7e9ba3640 ]
William reports kernel soft-lockups on some OVS topologies when TC mirred
egress->ingress action is hit by local TCP traffic [1].
The same can also be reproduced with SCTP (thanks Xin for verifying), when
client and server reach themselves through mirred egress to ingress, and
one of the two peers sends a "heartbeat" packet (from within a timer).
Enqueueing to backlog proved to fix this soft lockup; however, as Cong
noticed [2], we should preserve - when possible - the current mirred
behavior that counts as "overlimits" any eventual packet drop subsequent to
the mirred forwarding action [3]. A compromise solution might use the
backlog only when tcf_mirred_act() has a nest level greater than one:
change tcf_mirred_forward() accordingly.
Also, add a kselftest that can reproduce the lockup and verifies TC mirred
ability to account for further packet drops after TC mirred egress->ingress
(when the nest level is 1).
[1] https://lore.kernel.org/netdev/33dc43f587ec1388ba456b4915c75f02a8aae226.1663945716.git.dcaratti@redhat.com/
[2] https://lore.kernel.org/netdev/Y0w%2FWWY60gqrtGLp@pop-os.localdomain/
[3] such behavior is not guaranteed: for example, if RPS or skb RX
timestamping is enabled on the mirred target device, the kernel
can defer receiving the skb and return NET_RX_SUCCESS inside
tcf_mirred_forward().
BUG=b/261837988
RELEASE_NOTE=Fixed CVE-2022-4269 in the Linux kernel.
Reported-by: William Zhao <wizhao@redhat.com>
CC: Xin Long <lucien.xin@gmail.com>
Change-Id: I699233ddfa3997d92e6a98623ef5df78adcf2571
Signed-off-by: Davide Caratti <dcaratti@redhat.com>
Reviewed-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
[DP: adjusted context for linux-5.10.y]
Signed-off-by: Dragos-Marian Panait <dragos.panait@windriver.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-on: https://cos-review.googlesource.com/c/third_party/kernel/+/50534
Reviewed-by: Meena Shanmugam <meenashanmugam@google.com>
Tested-by: Cusky Presubmit Bot <presubmit@cos-infra-prod.iam.gserviceaccount.com>
2 files changed
