net/unix/af_unix.c

File Facts

System

Linux kernel

Corpus path

net/unix/af_unix.c

Extension

.c

Size

93430 bytes

Lines

3971

Domain

Networking Core

Bucket

Sockets, Protocols, Packet Path, And Network Policy

Inferred role

Networking Core: operation-table or driver-model contract

Status

pattern implementation candidate

Why This File Exists

Networking stack implementation surface: socket APIs, protocol dispatch, packet flow, routing, filtering, and network namespaces.

• Networking stack implementation surface: socket APIs, protocol dispatch, packet flow, routing, filtering, and network namespaces.
• Defines an operation table; this is where Linux turns generic core objects into subsystem-specific behavior.
• 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.
• Allocates kernel memory; connect allocation flags and lifetime to context constraints.
• Defines or uses C structs; map object ownership, embedded links, reference counts, and lock ownership.

Dependency Surface

• linux/bpf-cgroup.h
• linux/btf_ids.h
• linux/dcache.h
• linux/errno.h
• linux/fcntl.h
• linux/file.h
• linux/filter.h
• linux/fs.h
• linux/fs_struct.h
• linux/init.h
• linux/kernel.h
• linux/mount.h
• linux/namei.h
• linux/net.h
• linux/pidfs.h
• linux/poll.h
• linux/proc_fs.h
• linux/sched/signal.h
• linux/security.h
• linux/seq_file.h
• linux/skbuff.h
• linux/slab.h
• linux/socket.h
• linux/splice.h
• linux/string.h
• linux/uaccess.h
• net/af_unix.h
• net/net_namespace.h
• net/scm.h
• net/tcp_states.h
• uapi/linux/sockios.h
• uapi/linux/termios.h

Detected Declarations

• struct unix_peercred
• struct unix_stream_read_state
• struct bpf_unix_iter_state
• struct bpf_iter__unix
• function unix_table_lock_cmp_fn
• function unix_state_lock_cmp_fn
• function unix_recvq_lock_cmp_fn
• function unix_unbound_hash
• function unix_bsd_hash
• function unix_abstract_hash
• function unix_table_double_lock
• function unix_table_double_unlock
• function unix_get_secdata
• function unix_set_secdata
• function unix_secdata_eq
• function unix_get_secdata
• function unix_may_send
• function unix_recvq_full_lockless
• function unix_release_addr
• function unix_validate_addr
• function unix_mkname_bsd
• function __unix_remove_socket
• function __unix_insert_socket
• function __unix_set_addr_hash
• function unix_remove_socket
• function unix_insert_unbound_socket
• function unix_insert_bsd_socket
• function unix_remove_bsd_socket
• function sk_for_each
• function socket
• function unix_dgram_peer_wake_connect
• function unix_dgram_peer_wake_disconnect
• function unix_dgram_peer_wake_disconnect_wakeup
• function unix_dgram_peer_wake_me
• function unix_writable
• function unix_write_space
• function unix_dgram_disconnected
• function unix_sock_destructor
• function unix_skb_len
• function unix_release_sock
• function prepare_peercred
• function drop_peercred
• function init_peercred
• function update_peercred
• function copy_peercred
• function unix_may_passcred
• function unix_listen
• function unix_count_nr_fds

Annotated Snippet

static const struct proto_ops unix_stream_ops = {
	.family =	PF_UNIX,
	.owner =	THIS_MODULE,
	.release =	unix_release,
	.bind =		unix_bind,
	.connect =	unix_stream_connect,
	.socketpair =	unix_socketpair,
	.accept =	unix_accept,
	.getname =	unix_getname,
	.poll =		unix_poll,
	.ioctl =	unix_ioctl,
#ifdef CONFIG_COMPAT
	.compat_ioctl =	unix_compat_ioctl,
#endif
	.listen =	unix_listen,
	.shutdown =	unix_shutdown,
	.setsockopt =	unix_setsockopt,
	.sendmsg =	unix_stream_sendmsg,
	.recvmsg =	unix_stream_recvmsg,
	.read_skb =	unix_stream_read_skb,
	.mmap =		sock_no_mmap,
	.splice_read =	unix_stream_splice_read,
	.set_peek_off =	sk_set_peek_off,
	.show_fdinfo =	unix_show_fdinfo,
};

static const struct proto_ops unix_dgram_ops = {
	.family =	PF_UNIX,
	.owner =	THIS_MODULE,
	.release =	unix_release,
	.bind =		unix_bind,
	.connect =	unix_dgram_connect,
	.socketpair =	unix_socketpair,
	.accept =	sock_no_accept,
	.getname =	unix_getname,
	.poll =		unix_dgram_poll,
	.ioctl =	unix_ioctl,
#ifdef CONFIG_COMPAT
	.compat_ioctl =	unix_compat_ioctl,
#endif
	.listen =	sock_no_listen,
	.shutdown =	unix_shutdown,
	.sendmsg =	unix_dgram_sendmsg,
	.read_skb =	unix_read_skb,
	.recvmsg =	unix_dgram_recvmsg,
	.mmap =		sock_no_mmap,
	.set_peek_off =	sk_set_peek_off,
	.show_fdinfo =	unix_show_fdinfo,
};

static const struct proto_ops unix_seqpacket_ops = {
	.family =	PF_UNIX,
	.owner =	THIS_MODULE,
	.release =	unix_release,
	.bind =		unix_bind,
	.connect =	unix_stream_connect,
	.socketpair =	unix_socketpair,
	.accept =	unix_accept,
	.getname =	unix_getname,
	.poll =		unix_dgram_poll,
	.ioctl =	unix_ioctl,
#ifdef CONFIG_COMPAT
	.compat_ioctl =	unix_compat_ioctl,
#endif
	.listen =	unix_listen,
	.shutdown =	unix_shutdown,
	.sendmsg =	unix_seqpacket_sendmsg,
	.recvmsg =	unix_seqpacket_recvmsg,
	.mmap =		sock_no_mmap,
	.set_peek_off =	sk_set_peek_off,
	.show_fdinfo =	unix_show_fdinfo,
};

static void unix_close(struct sock *sk, long timeout)
{
	/* Nothing to do here, unix socket does not need a ->close().
	 * This is merely for sockmap.
	 */
}

static bool unix_bpf_bypass_getsockopt(int level, int optname)
{
	if (level == SOL_SOCKET) {
		switch (optname) {
		case SO_PEERPIDFD:
			return true;
		default:
			return false;
		}
	}

Annotation

• Immediate include surface: `linux/bpf-cgroup.h`, `linux/btf_ids.h`, `linux/dcache.h`, `linux/errno.h`, `linux/fcntl.h`, `linux/file.h`, `linux/filter.h`, `linux/fs.h`.
• Detected declarations: `struct unix_peercred`, `struct unix_stream_read_state`, `struct bpf_unix_iter_state`, `struct bpf_iter__unix`, `function unix_table_lock_cmp_fn`, `function unix_state_lock_cmp_fn`, `function unix_recvq_lock_cmp_fn`, `function unix_unbound_hash`, `function unix_bsd_hash`, `function unix_abstract_hash`.
• Atlas domain: Networking Core / Sockets, Protocols, Packet Path, And Network Policy.
• Implementation status: pattern 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.