On Tue, Jun 11, 2019 at 12:06 AM Michal Koutný <[email protected]> wrote:
>
> When a double-forking daemon spawns the shortlived forking process and
> we fail to classify it in time, the child does not inherit (the
> intended) cgroup membership.
>
> We could process all children after receiving PROC_EVENT_FORK to remedy
> this. But since we already have the timestamp logic introduced in
>
> 8953fc07c049 ("Changelog v2: * Use clock_gettime(2) for getting
> timestamp since a system boot. * Change parent_info's memory to
> dynamic allocation.")
>
> and it may be too much work for all fork(2) calls, we extend the usage
> of parent_info by assuming the parent would have changed its cgroup
> membership by our actions even if it terminated quickly.
>
> v2: Handle non-existent /proc/$PID/tasks as short-lived process too
> Use cgroup_get_last_errno() helper
>
> Signed-off-by: Michal Koutný <[email protected]>
Applied, thanks!
Dhaval
> ---
> src/daemon/cgrulesengd.c | 10 +++++++---
> 1 file changed, 7 insertions(+), 3 deletions(-)
>
> diff --git a/src/daemon/cgrulesengd.c b/src/daemon/cgrulesengd.c
> index 0d288f3ca916..0d90b8b114b8 100644
> --- a/src/daemon/cgrulesengd.c
> +++ b/src/daemon/cgrulesengd.c
> @@ -477,9 +477,13 @@ int cgre_process_event(const struct proc_event *ev,
> const int type)
> }
> ret = cgroup_change_cgroup_flags(euid, egid, procname, pid,
> CGFLAG_USECACHE);
> - if ((ret == ECGOTHER) && (errno == ESRCH)) {
> - /* A process finished already and that is not a problem. */
> - ret = 0;
> + if (ret == ECGOTHER) {
> + /* A process finished already but we may have missed changing
> it,
> + * make sure to apply to forked children. */
> + if (cgroup_get_last_errno() == ESRCH ||
> cgroup_get_last_errno() == ENOENT)
> + ret = cgre_store_parent_info(pid);
> + else
> + ret = 0;
> } else if (ret) {
> flog(LOG_WARNING,
> "Cgroup change for PID: %d, UID: %d, GID: %d,
> PROCNAME: %s FAILED! (Error Code: %d)\n",
> --
> 2.21.0
>
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