commit 0279957171 upstream.
Follows up on:
https://lore.kernel.org/all/20220809170518.164662-1-cascardo@canonical.com/
handle of 0 implies from/to of universe realm which is not very
sensible.
Lets see what this patch will do:
$sudo tc qdisc add dev $DEV root handle 1:0 prio
//lets manufacture a way to insert handle of 0
$sudo tc filter add dev $DEV parent 1:0 protocol ip prio 100 \
route to 0 from 0 classid 1:10 action ok
//gets rejected...
Error: handle of 0 is not valid.
We have an error talking to the kernel, -1
//lets create a legit entry..
sudo tc filter add dev $DEV parent 1:0 protocol ip prio 100 route from 10 \
classid 1:10 action ok
//what did the kernel insert?
$sudo tc filter ls dev $DEV parent 1:0
filter protocol ip pref 100 route chain 0
filter protocol ip pref 100 route chain 0 fh 0x000a8000 flowid 1:10 from 10
action order 1: gact action pass
random type none pass val 0
index 1 ref 1 bind 1
//Lets try to replace that legit entry with a handle of 0
$ sudo tc filter replace dev $DEV parent 1:0 protocol ip prio 100 \
handle 0x000a8000 route to 0 from 0 classid 1:10 action drop
Error: Replacing with handle of 0 is invalid.
We have an error talking to the kernel, -1
And last, lets run Cascardo's POC:
$ ./poc
0
0
-22
-22
-22
Signed-off-by: Jamal Hadi Salim <jhs@mojatatu.com>
Acked-by: Stephen Hemminger <stephen@networkplumber.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
c0931e464b