Johannes Weiner 04d2fea2b7 sched: psi: fix unprivileged polling against cgroups ... commit 8b39d20eceeda6c4eb23df1497f9ed2fffdc8f69 upstream. 519fabc7aa ("psi: remove 500ms min window size limitation for triggers") breaks unprivileged psi polling on cgroups. Historically, we had a privilege check for polling in the open() of a pressure file in /proc, but were erroneously missing it for the open() of cgroup pressure files. When unprivileged polling was introduced in d82caa2735 ("sched/psi: Allow unprivileged polling of N*2s period"), it needed to filter privileges depending on the exact polling parameters, and as such moved the CAP_SYS_RESOURCE check from the proc open() callback to psi_trigger_create(). Both the proc files as well as cgroup files go through this during write(). This implicitly added the missing check for privileges required for HT polling for cgroups. When 519fabc7aa ("psi: remove 500ms min window size limitation for triggers") followed right after to remove further restrictions on the RT polling window, it incorrectly assumed the cgroup privilege check was still missing and added it to the cgroup open(), mirroring what we used to do for proc files in the past. As a result, unprivileged poll requests that would be supported now get rejected when opening the cgroup pressure file for writing. Remove the cgroup open() check. psi_trigger_create() handles it. Fixes: 519fabc7aa ("psi: remove 500ms min window size limitation for triggers") Reported-by: Luca Boccassi <bluca@debian.org> Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Luca Boccassi <bluca@debian.org> Acked-by: Suren Baghdasaryan <surenb@google.com> Cc: stable@vger.kernel.org # 6.5+ Link: https://lore.kernel.org/r/20231026164114.2488682-1-hannes@cmpxchg.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>		2023-11-28 17:19:56 +00:00
..
Makefile	cgroup: Add misc cgroup controller	2021-04-04 13:34:46 -04:00
cgroup-internal.h	cgroup: make cgroup_is_threaded() and cgroup_is_thread_root() static	2023-06-05 10:31:41 -10:00
cgroup-v1.c	cgroup: Remove duplicates in cgroup v1 tasks file	2023-10-09 06:42:05 -10:00
cgroup.c	sched: psi: fix unprivileged polling against cgroups	2023-11-28 17:19:56 +00:00
cpuset.c	cgroup/cpuset: Fix load balance state in update_partition_sd_lb()	2023-11-20 11:58:53 +01:00
debug.c	kernel: cgroup: fix misuse of %x	2019-05-06 08:47:48 -07:00
freezer.c	cgroup: cleanup comments	2022-03-13 19:19:27 -10:00
legacy_freezer.c	cgroup,freezer: hold cpu_hotplug_lock before freezer_mutex in freezer_css_{online,offline}()	2023-06-12 06:39:48 -10:00
misc.c	cgroup/misc: Store atomic64_t reads to u64	2023-07-21 08:10:06 -10:00
namespace.c	cgroup:namespace: Remove unused cgroup_namespaces_init()	2023-08-14 14:29:47 -10:00
pids.c	cgroup: add pids.peak interface for pids controller	2022-09-04 09:26:51 -10:00
rdma.c	rdmacg: fix kernel-doc warnings in rdmacg	2023-06-05 09:45:14 -10:00
rstat.c	cgroup/rstat: Record the cumulative per-cpu time of cgroup and its descendants	2023-08-07 08:41:25 -10:00