Thread (22 messages) 22 messages, 7 authors, 2025-08-19

Re: [PATCH v3 bpf-next 0/4] Introduce bpf_cgroup_read_xattr

From: Christian Brauner <brauner@kernel.org>
Date: 2025-07-02 12:20:03
Also in: bpf, linux-fsdevel, lkml

On Tue, Jul 01, 2025 at 09:23:30AM -0700, Song Liu wrote:
On Tue, Jul 1, 2025 at 1:32 AM Christian Brauner [off-list ref] wrote:
quoted
On Fri, Jun 27, 2025 at 04:20:58PM +0000, Song Liu wrote:
quoted
quoted
On Jun 27, 2025, at 8:59 AM, Alexei Starovoitov [off-list ref] wrote:

On Thu, Jun 26, 2025 at 9:04 PM Song Liu [off-list ref] wrote:
quoted
On Thu, Jun 26, 2025 at 7:14 PM Alexei Starovoitov
[off-list ref] wrote:
[...]
quoted
./test_progs -t lsm_cgroup
Summary: 1/2 PASSED, 0 SKIPPED, 0 FAILED
./test_progs -t lsm_cgroup
Summary: 1/2 PASSED, 0 SKIPPED, 0 FAILED
./test_progs -t cgroup_xattr
Summary: 1/8 PASSED, 0 SKIPPED, 0 FAILED
./test_progs -t lsm_cgroup
test_lsm_cgroup_functional:PASS:bind(ETH_P_ALL) 0 nsec
(network_helpers.c:121: errno: Cannot assign requested address) Failed
to bind socket
test_lsm_cgroup_functional:FAIL:start_server unexpected start_server:
actual -1 < expected 0
(network_helpers.c:360: errno: Bad file descriptor) getsockopt(SOL_PROTOCOL)
test_lsm_cgroup_functional:FAIL:connect_to_fd unexpected
connect_to_fd: actual -1 < expected 0
test_lsm_cgroup_functional:FAIL:accept unexpected accept: actual -1 < expected 0
test_lsm_cgroup_functional:FAIL:getsockopt unexpected getsockopt:
actual -1 < expected 0
test_lsm_cgroup_functional:FAIL:sk_priority unexpected sk_priority:
actual 0 != expected 234
...
Summary: 0/1 PASSED, 0 SKIPPED, 1 FAILED


Song,
Please follow up with the fix for selftest.
It will be in bpf-next only.
The issue is because cgroup_xattr calls "ip link set dev lo up"
in setup, and calls "ip link set dev lo down" in cleanup. Most
other tests only call "ip link set dev lo up". IOW, it appears to
me that cgroup_xattr is doing the cleanup properly. To fix this,
we can either remove "dev lo down" from cgroup_xattr, or add
"dev lo up" to lsm_cgroups. Do you have any preference one
way or another?
It messes with "lo" without switching netns? Ouch.
Ah, I see the problem now.
quoted
Not sure what tests you copied that code from,
but all "ip" commands, ping_group_range, and sockets
don't need to be in the test. Instead of triggering
progs through lsm/socket_connect hook can't you use
a simple hook like lsm/bpf or lsm/file_open that doesn't require
networking setup ?
Yeah, let me fix the test with a different hook.
Where's the patch?
Here is a fix to kernel/bpf/helprs.c by Eduard:
https://lore.kernel.org/bpf/20250627175309.2710973-1-eddyz87@gmail.com/ (local)

This fix addresses build errors with certain config.

Here is my fix to the selftests:
https://lore.kernel.org/bpf/20250627191221.765921-1-song@kernel.org/ (local)

I didn't CC linux-fsdevel because all the changes are in the
selftests, and the error is independent of the new code.
Ah great, thank you for the info. That helped and we don't have to care then.
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