How to use u32 filters with clsact qdisc

[tsv1991]

I'd like to use u32 filters with clsact qdisc.
If I use the tc utility, this like:

$ tc qdisc add dev  br0 clsact
$ tc filter add dev br0 ingress protocol ip pref 2 u32 match ip dst 192.168.2.0/24 action pass

$ tc filter show dev br0 ingress
filter protocol ip pref 2 u32 chain 0
filter protocol ip pref 2 u32 chain 0 fh 800: ht divisor 1
filter protocol ip pref 2 u32 chain 0 fh 800::800 order 2048 key ht 800 bkt 0 terminal flowid not_in_hw
  match c0a80200/ffffff00 at 16
        action order 1: gact action pass
         random type none pass val 0
         index 1 ref 1 bind 1

But when I try to do it use pyroute2, I get error:

  return tuple(self._genlm_get(*argv, **kwarg))
          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 File "/usr/local/lib/python3.11/dist-packages/pyroute2/netlink/nlsocket.py", line 555, in get
   raise msg['header']['error']
pyroute2.netlink.exceptions.NetlinkError: (2, 'No such file or directory')

Of course the interface exists.

from pyroute2 import IPRoute, protocols

dev = "br0"

dst_ip_hex = "0xc0a80200"  # 192.168.2.0
dst_mask_hex = "0xffffff00"  # 255.255.255.0
offset = 16

ip = IPRoute()

dev_index = ip.link_lookup(ifname=dev)[0]
print(f"br0 index: {dev_index}")

ip.tc("add", "clsact", dev_index)

ip.tc("add-filter", "u32", dev_index,
    parent=0xfffffff1,
    prio=2,
    protocol=protocols.ETH_P_IP,
    target=0x800,
    keys=[f"{dst_ip_hex}/{dst_mask_hex}+{offset}"],
    action=dict(kind="gact", action="ok")
)

ip.close()

I'd appreciate it if you could help me find my mistake.

[svinota]

There was a wrong parent; the kernel expects there 0xfffffff2 in this case.

ip.tc("add-filter", "u32", dev_index,
    parent=0xfffffff2,  # <--- here was a wrong parent
    prio=2,
    protocol=protocols.ETH_P_IP,
    target=0x800,
    keys=[f"{dst_ip_hex}/{dst_mask_hex}+{offset}"],
    action=dict(kind="gact", action="ok")
)

Just for reference: https://github.com/iproute2/iproute2/blob/41710ace5e8fadff354f3dba67bf27ed3a3c5ae7/include/uapi/linux/pkt_sched.h#L80

There is a significant lack of user-friendliness in pyroute2 when it comes to traffic control management, so any contributions in this area are highly welcome.

[tsv1991]

Thank you!
You're really helpful. I don't know how can I contribute to pyroute2, because my programming skills not so good. But I can share user experiences to improve the library.