1 // SPDX-License-Identifier: GPL-2.0
2 /* Copyright (c) 2021 Cong Wang <cong.wang@bytedance.com> */
3
4 #include <linux/skmsg.h>
5 #include <linux/bpf.h>
6 #include <net/sock.h>
7 #include <net/af_unix.h>
8
9 #define unix_sk_has_data(__sk, __psock) \
10 ({ !skb_queue_empty(&__sk->sk_receive_queue) || \
11 !skb_queue_empty(&__psock->ingress_skb) || \
12 !list_empty(&__psock->ingress_msg); \
13 })
14
unix_msg_wait_data(struct sock * sk,struct sk_psock * psock,long timeo)15 static int unix_msg_wait_data(struct sock *sk, struct sk_psock *psock,
16 long timeo)
17 {
18 DEFINE_WAIT_FUNC(wait, woken_wake_function);
19 struct unix_sock *u = unix_sk(sk);
20 int ret = 0;
21
22 if (sk->sk_shutdown & RCV_SHUTDOWN)
23 return 1;
24
25 if (!timeo)
26 return ret;
27
28 add_wait_queue(sk_sleep(sk), &wait);
29 sk_set_bit(SOCKWQ_ASYNC_WAITDATA, sk);
30 if (!unix_sk_has_data(sk, psock)) {
31 mutex_unlock(&u->iolock);
32 wait_woken(&wait, TASK_INTERRUPTIBLE, timeo);
33 mutex_lock(&u->iolock);
34 ret = unix_sk_has_data(sk, psock);
35 }
36 sk_clear_bit(SOCKWQ_ASYNC_WAITDATA, sk);
37 remove_wait_queue(sk_sleep(sk), &wait);
38 return ret;
39 }
40
__unix_recvmsg(struct sock * sk,struct msghdr * msg,size_t len,int flags)41 static int __unix_recvmsg(struct sock *sk, struct msghdr *msg,
42 size_t len, int flags)
43 {
44 if (sk->sk_type == SOCK_DGRAM)
45 return __unix_dgram_recvmsg(sk, msg, len, flags);
46 else
47 return __unix_stream_recvmsg(sk, msg, len, flags);
48 }
49
unix_bpf_recvmsg(struct sock * sk,struct msghdr * msg,size_t len,int flags,int * addr_len)50 static int unix_bpf_recvmsg(struct sock *sk, struct msghdr *msg,
51 size_t len, int flags, int *addr_len)
52 {
53 struct unix_sock *u = unix_sk(sk);
54 struct sk_psock *psock;
55 int copied;
56
57 if (!len)
58 return 0;
59
60 psock = sk_psock_get(sk);
61 if (unlikely(!psock))
62 return __unix_recvmsg(sk, msg, len, flags);
63
64 mutex_lock(&u->iolock);
65 if (!skb_queue_empty(&sk->sk_receive_queue) &&
66 sk_psock_queue_empty(psock)) {
67 mutex_unlock(&u->iolock);
68 sk_psock_put(sk, psock);
69 return __unix_recvmsg(sk, msg, len, flags);
70 }
71
72 msg_bytes_ready:
73 copied = sk_msg_recvmsg(sk, psock, msg, len, flags);
74 if (!copied) {
75 long timeo;
76 int data;
77
78 timeo = sock_rcvtimeo(sk, flags & MSG_DONTWAIT);
79 data = unix_msg_wait_data(sk, psock, timeo);
80 if (data) {
81 if (!sk_psock_queue_empty(psock))
82 goto msg_bytes_ready;
83 mutex_unlock(&u->iolock);
84 sk_psock_put(sk, psock);
85 return __unix_recvmsg(sk, msg, len, flags);
86 }
87 copied = -EAGAIN;
88 }
89 mutex_unlock(&u->iolock);
90 sk_psock_put(sk, psock);
91 return copied;
92 }
93
94 static struct proto *unix_dgram_prot_saved __read_mostly;
95 static DEFINE_SPINLOCK(unix_dgram_prot_lock);
96 static struct proto unix_dgram_bpf_prot;
97
98 static struct proto *unix_stream_prot_saved __read_mostly;
99 static DEFINE_SPINLOCK(unix_stream_prot_lock);
100 static struct proto unix_stream_bpf_prot;
101
unix_dgram_bpf_rebuild_protos(struct proto * prot,const struct proto * base)102 static void unix_dgram_bpf_rebuild_protos(struct proto *prot, const struct proto *base)
103 {
104 *prot = *base;
105 prot->close = sock_map_close;
106 prot->recvmsg = unix_bpf_recvmsg;
107 prot->sock_is_readable = sk_msg_is_readable;
108 }
109
unix_stream_bpf_rebuild_protos(struct proto * prot,const struct proto * base)110 static void unix_stream_bpf_rebuild_protos(struct proto *prot,
111 const struct proto *base)
112 {
113 *prot = *base;
114 prot->close = sock_map_close;
115 prot->recvmsg = unix_bpf_recvmsg;
116 prot->sock_is_readable = sk_msg_is_readable;
117 prot->unhash = sock_map_unhash;
118 }
119
unix_dgram_bpf_check_needs_rebuild(struct proto * ops)120 static void unix_dgram_bpf_check_needs_rebuild(struct proto *ops)
121 {
122 if (unlikely(ops != smp_load_acquire(&unix_dgram_prot_saved))) {
123 spin_lock_bh(&unix_dgram_prot_lock);
124 if (likely(ops != unix_dgram_prot_saved)) {
125 unix_dgram_bpf_rebuild_protos(&unix_dgram_bpf_prot, ops);
126 smp_store_release(&unix_dgram_prot_saved, ops);
127 }
128 spin_unlock_bh(&unix_dgram_prot_lock);
129 }
130 }
131
unix_stream_bpf_check_needs_rebuild(struct proto * ops)132 static void unix_stream_bpf_check_needs_rebuild(struct proto *ops)
133 {
134 if (unlikely(ops != smp_load_acquire(&unix_stream_prot_saved))) {
135 spin_lock_bh(&unix_stream_prot_lock);
136 if (likely(ops != unix_stream_prot_saved)) {
137 unix_stream_bpf_rebuild_protos(&unix_stream_bpf_prot, ops);
138 smp_store_release(&unix_stream_prot_saved, ops);
139 }
140 spin_unlock_bh(&unix_stream_prot_lock);
141 }
142 }
143
unix_dgram_bpf_update_proto(struct sock * sk,struct sk_psock * psock,bool restore)144 int unix_dgram_bpf_update_proto(struct sock *sk, struct sk_psock *psock, bool restore)
145 {
146 if (sk->sk_type != SOCK_DGRAM)
147 return -EOPNOTSUPP;
148
149 if (restore) {
150 sk->sk_write_space = psock->saved_write_space;
151 sock_replace_proto(sk, psock->sk_proto);
152 return 0;
153 }
154
155 unix_dgram_bpf_check_needs_rebuild(psock->sk_proto);
156 sock_replace_proto(sk, &unix_dgram_bpf_prot);
157 return 0;
158 }
159
unix_stream_bpf_update_proto(struct sock * sk,struct sk_psock * psock,bool restore)160 int unix_stream_bpf_update_proto(struct sock *sk, struct sk_psock *psock, bool restore)
161 {
162 if (restore) {
163 sk->sk_write_space = psock->saved_write_space;
164 sock_replace_proto(sk, psock->sk_proto);
165 return 0;
166 }
167
168 unix_stream_bpf_check_needs_rebuild(psock->sk_proto);
169 sock_replace_proto(sk, &unix_stream_bpf_prot);
170 return 0;
171 }
172
unix_bpf_build_proto(void)173 void __init unix_bpf_build_proto(void)
174 {
175 unix_dgram_bpf_rebuild_protos(&unix_dgram_bpf_prot, &unix_dgram_proto);
176 unix_stream_bpf_rebuild_protos(&unix_stream_bpf_prot, &unix_stream_proto);
177
178 }
179
