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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
15static 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
41static 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
50static 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
72msg_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
94static struct proto *unix_dgram_prot_saved __read_mostly;
95static DEFINE_SPINLOCK(unix_dgram_prot_lock);
96static struct proto unix_dgram_bpf_prot;
97
98static struct proto *unix_stream_prot_saved __read_mostly;
99static DEFINE_SPINLOCK(unix_stream_prot_lock);
100static struct proto unix_stream_bpf_prot;
101
102static 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
110static 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
120static 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
132static 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
144int 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
160int unix_stream_bpf_update_proto(struct sock *sk, struct sk_psock *psock, bool restore)
161{
162 struct sock *sk_pair;
163
164 /* Restore does not decrement the sk_pair reference yet because we must
165 * keep the a reference to the socket until after an RCU grace period
166 * and any pending sends have completed.
167 */
168 if (restore) {
169 sk->sk_write_space = psock->saved_write_space;
170 sock_replace_proto(sk, psock->sk_proto);
171 return 0;
172 }
173
174 /* psock_update_sk_prot can be called multiple times if psock is
175 * added to multiple maps and/or slots in the same map. There is
176 * also an edge case where replacing a psock with itself can trigger
177 * an extra psock_update_sk_prot during the insert process. So it
178 * must be safe to do multiple calls. Here we need to ensure we don't
179 * increment the refcnt through sock_hold many times. There will only
180 * be a single matching destroy operation.
181 */
182 if (!psock->sk_pair) {
183 sk_pair = unix_peer(sk);
184 sock_hold(sk_pair);
185 psock->sk_pair = sk_pair;
186 }
187
188 unix_stream_bpf_check_needs_rebuild(psock->sk_proto);
189 sock_replace_proto(sk, &unix_stream_bpf_prot);
190 return 0;
191}
192
193void __init unix_bpf_build_proto(void)
194{
195 unix_dgram_bpf_rebuild_protos(&unix_dgram_bpf_prot, &unix_dgram_proto);
196 unix_stream_bpf_rebuild_protos(&unix_stream_bpf_prot, &unix_stream_proto);
197
198}
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
15static 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
41static 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
50static 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 psock = sk_psock_get(sk);
58 if (unlikely(!psock))
59 return __unix_recvmsg(sk, msg, len, flags);
60
61 mutex_lock(&u->iolock);
62 if (!skb_queue_empty(&sk->sk_receive_queue) &&
63 sk_psock_queue_empty(psock)) {
64 mutex_unlock(&u->iolock);
65 sk_psock_put(sk, psock);
66 return __unix_recvmsg(sk, msg, len, flags);
67 }
68
69msg_bytes_ready:
70 copied = sk_msg_recvmsg(sk, psock, msg, len, flags);
71 if (!copied) {
72 long timeo;
73 int data;
74
75 timeo = sock_rcvtimeo(sk, flags & MSG_DONTWAIT);
76 data = unix_msg_wait_data(sk, psock, timeo);
77 if (data) {
78 if (!sk_psock_queue_empty(psock))
79 goto msg_bytes_ready;
80 mutex_unlock(&u->iolock);
81 sk_psock_put(sk, psock);
82 return __unix_recvmsg(sk, msg, len, flags);
83 }
84 copied = -EAGAIN;
85 }
86 mutex_unlock(&u->iolock);
87 sk_psock_put(sk, psock);
88 return copied;
89}
90
91static struct proto *unix_dgram_prot_saved __read_mostly;
92static DEFINE_SPINLOCK(unix_dgram_prot_lock);
93static struct proto unix_dgram_bpf_prot;
94
95static struct proto *unix_stream_prot_saved __read_mostly;
96static DEFINE_SPINLOCK(unix_stream_prot_lock);
97static struct proto unix_stream_bpf_prot;
98
99static void unix_dgram_bpf_rebuild_protos(struct proto *prot, const struct proto *base)
100{
101 *prot = *base;
102 prot->close = sock_map_close;
103 prot->recvmsg = unix_bpf_recvmsg;
104 prot->sock_is_readable = sk_msg_is_readable;
105}
106
107static void unix_stream_bpf_rebuild_protos(struct proto *prot,
108 const struct proto *base)
109{
110 *prot = *base;
111 prot->close = sock_map_close;
112 prot->recvmsg = unix_bpf_recvmsg;
113 prot->sock_is_readable = sk_msg_is_readable;
114 prot->unhash = sock_map_unhash;
115}
116
117static void unix_dgram_bpf_check_needs_rebuild(struct proto *ops)
118{
119 if (unlikely(ops != smp_load_acquire(&unix_dgram_prot_saved))) {
120 spin_lock_bh(&unix_dgram_prot_lock);
121 if (likely(ops != unix_dgram_prot_saved)) {
122 unix_dgram_bpf_rebuild_protos(&unix_dgram_bpf_prot, ops);
123 smp_store_release(&unix_dgram_prot_saved, ops);
124 }
125 spin_unlock_bh(&unix_dgram_prot_lock);
126 }
127}
128
129static void unix_stream_bpf_check_needs_rebuild(struct proto *ops)
130{
131 if (unlikely(ops != smp_load_acquire(&unix_stream_prot_saved))) {
132 spin_lock_bh(&unix_stream_prot_lock);
133 if (likely(ops != unix_stream_prot_saved)) {
134 unix_stream_bpf_rebuild_protos(&unix_stream_bpf_prot, ops);
135 smp_store_release(&unix_stream_prot_saved, ops);
136 }
137 spin_unlock_bh(&unix_stream_prot_lock);
138 }
139}
140
141int unix_dgram_bpf_update_proto(struct sock *sk, struct sk_psock *psock, bool restore)
142{
143 if (sk->sk_type != SOCK_DGRAM)
144 return -EOPNOTSUPP;
145
146 if (restore) {
147 sk->sk_write_space = psock->saved_write_space;
148 sock_replace_proto(sk, psock->sk_proto);
149 return 0;
150 }
151
152 unix_dgram_bpf_check_needs_rebuild(psock->sk_proto);
153 sock_replace_proto(sk, &unix_dgram_bpf_prot);
154 return 0;
155}
156
157int unix_stream_bpf_update_proto(struct sock *sk, struct sk_psock *psock, bool restore)
158{
159 if (restore) {
160 sk->sk_write_space = psock->saved_write_space;
161 sock_replace_proto(sk, psock->sk_proto);
162 return 0;
163 }
164
165 unix_stream_bpf_check_needs_rebuild(psock->sk_proto);
166 sock_replace_proto(sk, &unix_stream_bpf_prot);
167 return 0;
168}
169
170void __init unix_bpf_build_proto(void)
171{
172 unix_dgram_bpf_rebuild_protos(&unix_dgram_bpf_prot, &unix_dgram_proto);
173 unix_stream_bpf_rebuild_protos(&unix_stream_bpf_prot, &unix_stream_proto);
174
175}