Re: [PATCH v3 17/70] nstree: add listns()
From: Simon Horman <horms@kernel.org>
Date: 2025-10-28 10:36:36
Also in:
bpf, cgroups, linux-fsdevel, lkml
On Fri, Oct 24, 2025 at 12:52:46PM +0200, Christian Brauner wrote: ...
quoted hunk ↗ jump to hunk
diff --git a/kernel/nstree.c b/kernel/nstree.c
...
+static ssize_t do_listns(struct klistns *kls)
+{
+ u64 *ns_ids = kls->kns_ids;
+ size_t nr_ns_ids = kls->nr_ns_ids;
+ struct ns_common *ns, *first_ns = NULL;
+ struct ns_tree *ns_tree = NULL;
+ const struct list_head *head;
+ struct user_namespace *user_ns;
+ u32 ns_type;
+ ssize_t ret;
+
+ if (hweight32(kls->ns_type) == 1)
+ ns_type = kls->ns_type;
+ else
+ ns_type = 0;
+
+ if (ns_type) {
+ ns_tree = ns_tree_from_type(ns_type);
+ if (!ns_tree)
+ return -EINVAL;
+ }
+
+ if (kls->last_ns_id) {
+ kls->first_ns = lookup_ns_id_at(kls->last_ns_id + 1, ns_type);
+ if (!kls->first_ns)
+ return -ENOENT;
+ first_ns = kls->first_ns;
+ }
+
+ ret = 0;
+ if (ns_tree)
+ head = &ns_tree->ns_list;
+ else
+ head = &ns_unified_list;
+
+ guard(rcu)();
+ if (!first_ns)
+ first_ns = first_ns_common(head, ns_tree);
+
+ for (ns = first_ns; !ns_common_is_head(ns, head, ns_tree) && nr_ns_ids;
+ ns = next_ns_common(ns, ns_tree)) {
+ if (kls->ns_type && !(kls->ns_type & ns->ns_type))
+ continue;
+ if (!ns_get_unless_inactive(ns))
+ continue;
+ /* Check permissions */
+ if (!ns->ops)
+ user_ns = NULL;Hi Christian, Here it is assumed that ns->ops may be NULL.
+ else
+ user_ns = ns->ops->owner(ns);
+ if (!user_ns)
+ user_ns = &init_user_ns;
+ if (ns_capable_noaudit(user_ns, CAP_SYS_ADMIN) ||
+ is_current_namespace(ns) ||
+ ((ns->ns_type == CLONE_NEWUSER) && ns_capable_noaudit(to_user_ns(ns), CAP_SYS_ADMIN))) {
+ *ns_ids++ = ns->ns_id;
+ nr_ns_ids--;
+ ret++;
+ }
+ if (need_resched())
+ cond_resched_rcu();
+ /* doesn't sleep */
+ ns->ops->put(ns);And, if so, it isn't clear to me why that wouldn't also be the case here. Flagged by Smatch.
+ } + + return ret; +}
...