Re: [PATCH bpf-next v2 01/28] bpf: add new is_sys_admin_prog_type() helper

On Sat, Mar 05, 2022 at 11:07:04AM +0100, Benjamin Tissoires wrote:

On Sat, Mar 5, 2022 at 12:12 AM Song Liu song@kernel.org wrote:

...

On Fri, Mar 4, 2022 at 9:30 AM Benjamin Tissoires benjamin.tissoires@redhat.com wrote:

...

LIRC_MODE2 does not really need net_admin capability, but only sys_admin.

Extract a new helper for it, it will be also used for the HID bpf implementation.

Cc: Sean Young sean@mess.org Signed-off-by: Benjamin Tissoires benjamin.tissoires@redhat.com

---

new in v2

kernel/bpf/syscall.c | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index db402ebc5570..cc570891322b 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -2165,7 +2165,6 @@ static bool is_net_admin_prog_type(enum bpf_prog_type prog_type) case BPF_PROG_TYPE_LWT_SEG6LOCAL: case BPF_PROG_TYPE_SK_SKB: case BPF_PROG_TYPE_SK_MSG:

•   case BPF_PROG_TYPE_LIRC_MODE2:
    case BPF_PROG_TYPE_FLOW_DISSECTOR:
    case BPF_PROG_TYPE_CGROUP_DEVICE:
    case BPF_PROG_TYPE_CGROUP_SOCK:
  

@@ -2202,6 +2201,17 @@ static bool is_perfmon_prog_type(enum bpf_prog_type prog_type) } }

+static bool is_sys_admin_prog_type(enum bpf_prog_type prog_type) +{

•   switch (prog_type) {
  

•   case BPF_PROG_TYPE_LIRC_MODE2:
  

•   case BPF_PROG_TYPE_EXT: /* extends any prog */
  

•           return true;
  

•   default:
  

•           return false;
  

•   }
  

+}

I am not sure whether we should do this. This is a behavior change, that may break some user space. Also, BPF_PROG_TYPE_EXT is checked in is_perfmon_prog_type(), and this change will make that case useless.

Sure, I can drop it from v3 and make this function appear for HID only.

For BPF_PROG_TYPE_LIRC_MODE2, I don't think this change will break userspace. This is called from ir-keytable(1) which is called from udev. It should have all the necessary permissions.

In addition, the vast majority IR decoders are non-bpf. bpf ir decoders have very few users at the moment.

I am working on completely new userspace tooling which will make extensive use of bpf ir decoding with full lircd and IRP compatibility, but this is not finished yet (see https://github.com/seanyoung/cir).

Thanks

Sean