diff options
Diffstat (limited to '')
| -rw-r--r-- | net/unix/unix_bpf.c | 198 |
1 files changed, 198 insertions, 0 deletions
diff --git a/net/unix/unix_bpf.c b/net/unix/unix_bpf.c new file mode 100644 index 000000000..bd84785bf --- /dev/null +++ b/net/unix/unix_bpf.c @@ -0,0 +1,198 @@ +// 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) +{ + struct sock *sk_pair; + + /* Restore does not decrement the sk_pair reference yet because we must + * keep the a reference to the socket until after an RCU grace period + * and any pending sends have completed. + */ + if (restore) { + sk->sk_write_space = psock->saved_write_space; + sock_replace_proto(sk, psock->sk_proto); + return 0; + } + + /* psock_update_sk_prot can be called multiple times if psock is + * added to multiple maps and/or slots in the same map. There is + * also an edge case where replacing a psock with itself can trigger + * an extra psock_update_sk_prot during the insert process. So it + * must be safe to do multiple calls. Here we need to ensure we don't + * increment the refcnt through sock_hold many times. There will only + * be a single matching destroy operation. + */ + if (!psock->sk_pair) { + sk_pair = unix_peer(sk); + sock_hold(sk_pair); + psock->sk_pair = sk_pair; + } + + 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); + +} |