On Wed, Jul 23, 2025 at 09:18:51AM +1000, Aleksa Sarai wrote:
This check will be needed in later patches, and there's no point open-coding it each time.
Signed-off-by: Aleksa Sarai cyphar@cyphar.com
include/linux/pid_namespace.h | 9 +++++++++ kernel/pid_namespace.c | 23 +++++++++++++++-------- 2 files changed, 24 insertions(+), 8 deletions(-)
diff --git a/include/linux/pid_namespace.h b/include/linux/pid_namespace.h index 7c67a5811199..17fdc059f8da 100644 --- a/include/linux/pid_namespace.h +++ b/include/linux/pid_namespace.h @@ -84,6 +84,9 @@ extern void zap_pid_ns_processes(struct pid_namespace *pid_ns); extern int reboot_pid_ns(struct pid_namespace *pid_ns, int cmd); extern void put_pid_ns(struct pid_namespace *ns); +extern bool pidns_is_ancestor(struct pid_namespace *child,
struct pid_namespace *ancestor);#else /* !CONFIG_PID_NS */ #include <linux/err.h> @@ -118,6 +121,12 @@ static inline int reboot_pid_ns(struct pid_namespace *pid_ns, int cmd) { return 0; }
+static inline bool pidns_is_ancestor(struct pid_namespace *child,
struct pid_namespace *ancestor)+{
- return false;
+} #endif /* CONFIG_PID_NS */ extern struct pid_namespace *task_active_pid_ns(struct task_struct *tsk); diff --git a/kernel/pid_namespace.c b/kernel/pid_namespace.c index 7098ed44e717..c2783c5fa90b 100644 --- a/kernel/pid_namespace.c +++ b/kernel/pid_namespace.c @@ -390,11 +390,24 @@ static void pidns_put(struct ns_common *ns) put_pid_ns(to_pid_ns(ns)); } +bool pidns_is_ancestor(struct pid_namespace *child,
struct pid_namespace *ancestor)+{
- struct pid_namespace *ns;
- if (child->level < ancestor->level)
return false;- for (ns = child; ns->level > ancestor->level; ns = ns->parent)
;- return ns == ancestor;
+} +EXPORT_SYMBOL_GPL(pidns_is_ancestor);
Why do you need to export this? Afaict, this is only used from procfs and iirc procfs cannot be a module. This could also be a static inline completely in the header? Otherwise this looks good.