1 // SPDX-License-Identifier: GPL-2.0 2 /* Copyright (c) 2022 Bobby Eshleman <bobby.eshleman@bytedance.com> 3 * 4 * Based off of net/unix/unix_bpf.c 5 */ 6 7 #include <linux/bpf.h> 8 #include <linux/module.h> 9 #include <linux/skmsg.h> 10 #include <linux/socket.h> 11 #include <linux/wait.h> 12 #include <net/af_vsock.h> 13 #include <net/sock.h> 14 15 #define vsock_sk_has_data(__sk, __psock) \ 16 ({ !skb_queue_empty(&(__sk)->sk_receive_queue) || \ 17 !skb_queue_empty(&(__psock)->ingress_skb) || \ 18 !list_empty(&(__psock)->ingress_msg); \ 19 }) 20 21 static struct proto *vsock_prot_saved __read_mostly; 22 static DEFINE_SPINLOCK(vsock_prot_lock); 23 static struct proto vsock_bpf_prot; 24 25 static bool vsock_has_data(struct sock *sk, struct sk_psock *psock) 26 { 27 struct vsock_sock *vsk = vsock_sk(sk); 28 s64 ret; 29 30 ret = vsock_connectible_has_data(vsk); 31 if (ret > 0) 32 return true; 33 34 return vsock_sk_has_data(sk, psock); 35 } 36 37 static bool vsock_msg_wait_data(struct sock *sk, struct sk_psock *psock, long timeo) 38 { 39 bool ret; 40 41 DEFINE_WAIT_FUNC(wait, woken_wake_function); 42 43 if (sk->sk_shutdown & RCV_SHUTDOWN) 44 return true; 45 46 if (!timeo) 47 return false; 48 49 add_wait_queue(sk_sleep(sk), &wait); 50 sk_set_bit(SOCKWQ_ASYNC_WAITDATA, sk); 51 ret = vsock_has_data(sk, psock); 52 if (!ret) { 53 wait_woken(&wait, TASK_INTERRUPTIBLE, timeo); 54 ret = vsock_has_data(sk, psock); 55 } 56 sk_clear_bit(SOCKWQ_ASYNC_WAITDATA, sk); 57 remove_wait_queue(sk_sleep(sk), &wait); 58 return ret; 59 } 60 61 static int __vsock_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, int flags) 62 { 63 struct socket *sock = sk->sk_socket; 64 int err; 65 66 if (sk->sk_type == SOCK_STREAM || sk->sk_type == SOCK_SEQPACKET) 67 err = __vsock_connectible_recvmsg(sock, msg, len, flags); 68 else if (sk->sk_type == SOCK_DGRAM) 69 err = __vsock_dgram_recvmsg(sock, msg, len, flags); 70 else 71 err = -EPROTOTYPE; 72 73 return err; 74 } 75 76 static int vsock_bpf_recvmsg(struct sock *sk, struct msghdr *msg, 77 size_t len, int flags, int *addr_len) 78 { 79 struct sk_psock *psock; 80 int copied; 81 82 psock = sk_psock_get(sk); 83 if (unlikely(!psock)) 84 return __vsock_recvmsg(sk, msg, len, flags); 85 86 lock_sock(sk); 87 if (vsock_has_data(sk, psock) && sk_psock_queue_empty(psock)) { 88 release_sock(sk); 89 sk_psock_put(sk, psock); 90 return __vsock_recvmsg(sk, msg, len, flags); 91 } 92 93 copied = sk_msg_recvmsg(sk, psock, msg, len, flags); 94 while (copied == 0) { 95 long timeo = sock_rcvtimeo(sk, flags & MSG_DONTWAIT); 96 97 if (!vsock_msg_wait_data(sk, psock, timeo)) { 98 copied = -EAGAIN; 99 break; 100 } 101 102 if (sk_psock_queue_empty(psock)) { 103 release_sock(sk); 104 sk_psock_put(sk, psock); 105 return __vsock_recvmsg(sk, msg, len, flags); 106 } 107 108 copied = sk_msg_recvmsg(sk, psock, msg, len, flags); 109 } 110 111 release_sock(sk); 112 sk_psock_put(sk, psock); 113 114 return copied; 115 } 116 117 static void vsock_bpf_rebuild_protos(struct proto *prot, const struct proto *base) 118 { 119 *prot = *base; 120 prot->close = sock_map_close; 121 prot->recvmsg = vsock_bpf_recvmsg; 122 prot->sock_is_readable = sk_msg_is_readable; 123 } 124 125 static void vsock_bpf_check_needs_rebuild(struct proto *ops) 126 { 127 /* Paired with the smp_store_release() below. */ 128 if (unlikely(ops != smp_load_acquire(&vsock_prot_saved))) { 129 spin_lock_bh(&vsock_prot_lock); 130 if (likely(ops != vsock_prot_saved)) { 131 vsock_bpf_rebuild_protos(&vsock_bpf_prot, ops); 132 /* Make sure proto function pointers are updated before publishing the 133 * pointer to the struct. 134 */ 135 smp_store_release(&vsock_prot_saved, ops); 136 } 137 spin_unlock_bh(&vsock_prot_lock); 138 } 139 } 140 141 int vsock_bpf_update_proto(struct sock *sk, struct sk_psock *psock, bool restore) 142 { 143 struct vsock_sock *vsk; 144 145 if (restore) { 146 sk->sk_write_space = psock->saved_write_space; 147 sock_replace_proto(sk, psock->sk_proto); 148 return 0; 149 } 150 151 vsk = vsock_sk(sk); 152 if (!vsk->transport) 153 return -ENODEV; 154 155 if (!vsk->transport->read_skb) 156 return -EOPNOTSUPP; 157 158 vsock_bpf_check_needs_rebuild(psock->sk_proto); 159 sock_replace_proto(sk, &vsock_bpf_prot); 160 return 0; 161 } 162 163 void __init vsock_bpf_build_proto(void) 164 { 165 vsock_bpf_rebuild_protos(&vsock_bpf_prot, &vsock_proto); 166 } 167