// SPDX-License-Identifier: GPL-2.0 /* Copyright (c) 2021 Cong Wang <cong.wang@bytedance.com> */ #include <linux/skmsg.h> #include <linux/bpf.h> #include <net/sock.h> #include <net/af_unix.h> #define unix_sk_has_data(__sk, __psock) \ ({ !skb_queue_empty(&__sk->sk_receive_queue) || \ !skb_queue_empty(&__psock->ingress_skb) || \ !list_empty(&__psock->ingress_msg); \ }) static int unix_msg_wait_data(struct sock *sk, struct sk_psock *psock, long timeo) { DEFINE_WAIT_FUNC(wait, woken_wake_function); struct unix_sock *u = unix_sk(sk); int ret = 0; if (sk->sk_shutdown & RCV_SHUTDOWN) return 1; if (!timeo) return ret; add_wait_queue(sk_sleep(sk), &wait); sk_set_bit(SOCKWQ_ASYNC_WAITDATA, sk); if (!unix_sk_has_data(sk, psock)) { mutex_unlock(&u->iolock); wait_woken(&wait, TASK_INTERRUPTIBLE, timeo); mutex_lock(&u->iolock); ret = unix_sk_has_data(sk, psock); } sk_clear_bit(SOCKWQ_ASYNC_WAITDATA, sk); remove_wait_queue(sk_sleep(sk), &wait); return ret; } static int __unix_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, int flags) { if (sk->sk_type == SOCK_DGRAM) return __unix_dgram_recvmsg(sk, msg, len, flags); else return __unix_stream_recvmsg(sk, msg, len, flags); } static int unix_bpf_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, int flags, int *addr_len) { struct unix_sock *u = unix_sk(sk); struct sk_psock *psock; int copied; if (!len) return 0; psock = sk_psock_get(sk); if (unlikely(!psock)) return __unix_recvmsg(sk, msg, len, flags); mutex_lock(&u->iolock); if (!skb_queue_empty(&sk->sk_receive_queue) && sk_psock_queue_empty(psock)) { mutex_unlock(&u->iolock); sk_psock_put(sk, psock); return __unix_recvmsg(sk, msg, len, flags); } msg_bytes_ready: copied = sk_msg_recvmsg(sk, psock, msg, len, flags); if (!copied) { long timeo; int data; timeo = sock_rcvtimeo(sk, flags & MSG_DONTWAIT); data = unix_msg_wait_data(sk, psock, timeo); if (data) { if (!sk_psock_queue_empty(psock)) goto msg_bytes_ready; mutex_unlock(&u->iolock); sk_psock_put(sk, psock); return __unix_recvmsg(sk, msg, len, flags); } copied = -EAGAIN; } mutex_unlock(&u->iolock); sk_psock_put(sk, psock); return copied; } static struct proto *unix_dgram_prot_saved __read_mostly; static DEFINE_SPINLOCK(unix_dgram_prot_lock); static struct proto unix_dgram_bpf_prot; static struct proto *unix_stream_prot_saved __read_mostly; static DEFINE_SPINLOCK(unix_stream_prot_lock); static struct proto unix_stream_bpf_prot; static void unix_dgram_bpf_rebuild_protos(struct proto *prot, const struct proto *base) { *prot = *base; prot->close = sock_map_close; prot->recvmsg = unix_bpf_recvmsg; prot->sock_is_readable = sk_msg_is_readable; } static void unix_stream_bpf_rebuild_protos(struct proto *prot, const struct proto *base) { *prot = *base; prot->close = sock_map_close; prot->recvmsg = unix_bpf_recvmsg; prot->sock_is_readable = sk_msg_is_readable; prot->unhash = sock_map_unhash; } static void unix_dgram_bpf_check_needs_rebuild(struct proto *ops) { if (unlikely(ops != smp_load_acquire(&unix_dgram_prot_saved))) { spin_lock_bh(&unix_dgram_prot_lock); if (likely(ops != unix_dgram_prot_saved)) { unix_dgram_bpf_rebuild_protos(&unix_dgram_bpf_prot, ops); smp_store_release(&unix_dgram_prot_saved, ops); } spin_unlock_bh(&unix_dgram_prot_lock); } } static void unix_stream_bpf_check_needs_rebuild(struct proto *ops) { if (unlikely(ops != smp_load_acquire(&unix_stream_prot_saved))) { spin_lock_bh(&unix_stream_prot_lock); if (likely(ops != unix_stream_prot_saved)) { unix_stream_bpf_rebuild_protos(&unix_stream_bpf_prot, ops); smp_store_release(&unix_stream_prot_saved, ops); } spin_unlock_bh(&unix_stream_prot_lock); } } int unix_dgram_bpf_update_proto(struct sock *sk, struct sk_psock *psock, bool restore) { if (sk->sk_type != SOCK_DGRAM) return -EOPNOTSUPP; if (restore) { sk->sk_write_space = psock->saved_write_space; sock_replace_proto(sk, psock->sk_proto); return 0; } unix_dgram_bpf_check_needs_rebuild(psock->sk_proto); sock_replace_proto(sk, &unix_dgram_bpf_prot); return 0; } int unix_stream_bpf_update_proto(struct sock *sk, struct sk_psock *psock, bool restore) { if (restore) { sk->sk_write_space = psock->saved_write_space; sock_replace_proto(sk, psock->sk_proto); return 0; } unix_stream_bpf_check_needs_rebuild(psock->sk_proto); sock_replace_proto(sk, &unix_stream_bpf_prot); return 0; } void __init unix_bpf_build_proto(void) { unix_dgram_bpf_rebuild_protos(&unix_dgram_bpf_prot, &unix_dgram_proto); unix_stream_bpf_rebuild_protos(&unix_stream_bpf_prot, &unix_stream_proto); }