kernel/nstree.c

File Facts

System

Linux kernel

Corpus path

kernel/nstree.c

Extension

.c

Size

18828 bytes

Lines

793

Domain

Core OS

Bucket

Scheduler, Processes, Timers, Sync, And Syscalls

Inferred role

Core OS: syscall or user/kernel boundary

Status

core implementation candidate

Why This File Exists

Core operating-system implementation surface: boot, tasks, memory, VFS, syscall-facing interfaces, synchronization, credentials, and isolation.

• Core operating-system implementation surface: boot, tasks, memory, VFS, syscall-facing interfaces, synchronization, credentials, and isolation.
• Defines or participates in a user/kernel boundary; inspect argument validation, copy_from_user/copy_to_user, credentials, and dispatch target.
• Touches user memory; correctness depends on fault-safe copying and privilege boundary handling.
• Uses kernel synchronization; read lock ordering, sleepability, and interrupt context assumptions before translating.
• Defines or uses C structs; map object ownership, embedded links, reference counts, and lock ownership.

Dependency Surface

• linux/nstree.h
• linux/proc_ns.h
• linux/rculist.h
• linux/vfsdebug.h
• linux/syscalls.h
• linux/user_namespace.h

Detected Declarations

• syscall listns
• struct klistns
• function ns_tree_node_init
• function ns_tree_root_init
• function ns_tree_node_empty
• function int
• function ns_tree_node_del
• function ns_id_cmp
• function ns_cmp
• function ns_cmp_unified
• function ns_cmp_owner
• function __ns_tree_add_raw
• function __ns_tree_remove
• function ns_find
• function ns_find_unified
• function __ns_tree_gen_id
• function __free_klistns_free
• function copy_ns_id_req
• function prepare_klistns
• function ns_requested
• function may_list_ns
• function ns_put
• function legitimize_ns
• function do_listns_userns
• function ns_common_is_head
• function do_listns
• export net_ns_tree
• export __ns_tree_remove

Annotated Snippet

SYSCALL_DEFINE4(listns, const struct ns_id_req __user *, req,
		u64 __user *, ns_ids, size_t, nr_ns_ids, unsigned int, flags)
{
	struct klistns klns __free(klistns_free) = {};
	const size_t maxcount = 1000000;
	struct ns_id_req kreq;
	ssize_t ret;

	if (flags)
		return -EINVAL;

	if (unlikely(nr_ns_ids > maxcount))
		return -EOVERFLOW;

	if (!access_ok(ns_ids, nr_ns_ids * sizeof(*ns_ids)))
		return -EFAULT;

	ret = copy_ns_id_req(req, &kreq);
	if (ret)
		return ret;

	ret = prepare_klistns(&klns, &kreq, ns_ids, nr_ns_ids);
	if (ret)
		return ret;

	if (kreq.user_ns_id)
		return do_listns_userns(&klns);

	return do_listns(&klns);
}

Annotation

• Immediate include surface: `linux/nstree.h`, `linux/proc_ns.h`, `linux/rculist.h`, `linux/vfsdebug.h`, `linux/syscalls.h`, `linux/user_namespace.h`.
• Detected declarations: `syscall listns`, `struct klistns`, `function ns_tree_node_init`, `function ns_tree_root_init`, `function ns_tree_node_empty`, `function int`, `function ns_tree_node_del`, `function ns_id_cmp`, `function ns_cmp`, `function ns_cmp_unified`.
• Atlas domain: Core OS / Scheduler, Processes, Timers, Sync, And Syscalls.
• Implementation status: core implementation candidate.
• This snippet crosses the user/kernel memory boundary; validate fault handling and access checks before translating the pattern.
• Synchronization appears in or near this file; preserve lock ordering, sleepability, and interrupt-context constraints.

Implementation Notes

• This generated page is the file-by-file coverage layer; curated subsystem chapters should link here when they synthesize a multi-file control flow.
• Core OS pages should be promoted from atlas-only to deep-reviewed when they explain data structures, invariants, locking, lifecycle, and C implementation snippets.
• Driver-family pages are intentionally pattern-oriented unless they are part of the selected PCIe/NVMe representative device path.