| // 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; |
| |
| 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; |
| WRITE_ONCE(sk->sk_prot, psock->sk_proto); |
| return 0; |
| } |
| |
| unix_dgram_bpf_check_needs_rebuild(psock->sk_proto); |
| WRITE_ONCE(sk->sk_prot, &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; |
| WRITE_ONCE(sk->sk_prot, psock->sk_proto); |
| return 0; |
| } |
| |
| unix_stream_bpf_check_needs_rebuild(psock->sk_proto); |
| WRITE_ONCE(sk->sk_prot, &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); |
| |
| } |