0001
0002
0003
0004 #include <linux/skmsg.h>
0005 #include <linux/bpf.h>
0006 #include <net/sock.h>
0007 #include <net/af_unix.h>
0008
0009 #define unix_sk_has_data(__sk, __psock) \
0010 ({ !skb_queue_empty(&__sk->sk_receive_queue) || \
0011 !skb_queue_empty(&__psock->ingress_skb) || \
0012 !list_empty(&__psock->ingress_msg); \
0013 })
0014
0015 static int unix_msg_wait_data(struct sock *sk, struct sk_psock *psock,
0016 long timeo)
0017 {
0018 DEFINE_WAIT_FUNC(wait, woken_wake_function);
0019 struct unix_sock *u = unix_sk(sk);
0020 int ret = 0;
0021
0022 if (sk->sk_shutdown & RCV_SHUTDOWN)
0023 return 1;
0024
0025 if (!timeo)
0026 return ret;
0027
0028 add_wait_queue(sk_sleep(sk), &wait);
0029 sk_set_bit(SOCKWQ_ASYNC_WAITDATA, sk);
0030 if (!unix_sk_has_data(sk, psock)) {
0031 mutex_unlock(&u->iolock);
0032 wait_woken(&wait, TASK_INTERRUPTIBLE, timeo);
0033 mutex_lock(&u->iolock);
0034 ret = unix_sk_has_data(sk, psock);
0035 }
0036 sk_clear_bit(SOCKWQ_ASYNC_WAITDATA, sk);
0037 remove_wait_queue(sk_sleep(sk), &wait);
0038 return ret;
0039 }
0040
0041 static int __unix_recvmsg(struct sock *sk, struct msghdr *msg,
0042 size_t len, int flags)
0043 {
0044 if (sk->sk_type == SOCK_DGRAM)
0045 return __unix_dgram_recvmsg(sk, msg, len, flags);
0046 else
0047 return __unix_stream_recvmsg(sk, msg, len, flags);
0048 }
0049
0050 static int unix_bpf_recvmsg(struct sock *sk, struct msghdr *msg,
0051 size_t len, int flags, int *addr_len)
0052 {
0053 struct unix_sock *u = unix_sk(sk);
0054 struct sk_psock *psock;
0055 int copied;
0056
0057 psock = sk_psock_get(sk);
0058 if (unlikely(!psock))
0059 return __unix_recvmsg(sk, msg, len, flags);
0060
0061 mutex_lock(&u->iolock);
0062 if (!skb_queue_empty(&sk->sk_receive_queue) &&
0063 sk_psock_queue_empty(psock)) {
0064 mutex_unlock(&u->iolock);
0065 sk_psock_put(sk, psock);
0066 return __unix_recvmsg(sk, msg, len, flags);
0067 }
0068
0069 msg_bytes_ready:
0070 copied = sk_msg_recvmsg(sk, psock, msg, len, flags);
0071 if (!copied) {
0072 long timeo;
0073 int data;
0074
0075 timeo = sock_rcvtimeo(sk, flags & MSG_DONTWAIT);
0076 data = unix_msg_wait_data(sk, psock, timeo);
0077 if (data) {
0078 if (!sk_psock_queue_empty(psock))
0079 goto msg_bytes_ready;
0080 mutex_unlock(&u->iolock);
0081 sk_psock_put(sk, psock);
0082 return __unix_recvmsg(sk, msg, len, flags);
0083 }
0084 copied = -EAGAIN;
0085 }
0086 mutex_unlock(&u->iolock);
0087 sk_psock_put(sk, psock);
0088 return copied;
0089 }
0090
0091 static struct proto *unix_dgram_prot_saved __read_mostly;
0092 static DEFINE_SPINLOCK(unix_dgram_prot_lock);
0093 static struct proto unix_dgram_bpf_prot;
0094
0095 static struct proto *unix_stream_prot_saved __read_mostly;
0096 static DEFINE_SPINLOCK(unix_stream_prot_lock);
0097 static struct proto unix_stream_bpf_prot;
0098
0099 static void unix_dgram_bpf_rebuild_protos(struct proto *prot, const struct proto *base)
0100 {
0101 *prot = *base;
0102 prot->close = sock_map_close;
0103 prot->recvmsg = unix_bpf_recvmsg;
0104 prot->sock_is_readable = sk_msg_is_readable;
0105 }
0106
0107 static void unix_stream_bpf_rebuild_protos(struct proto *prot,
0108 const struct proto *base)
0109 {
0110 *prot = *base;
0111 prot->close = sock_map_close;
0112 prot->recvmsg = unix_bpf_recvmsg;
0113 prot->sock_is_readable = sk_msg_is_readable;
0114 prot->unhash = sock_map_unhash;
0115 }
0116
0117 static void unix_dgram_bpf_check_needs_rebuild(struct proto *ops)
0118 {
0119 if (unlikely(ops != smp_load_acquire(&unix_dgram_prot_saved))) {
0120 spin_lock_bh(&unix_dgram_prot_lock);
0121 if (likely(ops != unix_dgram_prot_saved)) {
0122 unix_dgram_bpf_rebuild_protos(&unix_dgram_bpf_prot, ops);
0123 smp_store_release(&unix_dgram_prot_saved, ops);
0124 }
0125 spin_unlock_bh(&unix_dgram_prot_lock);
0126 }
0127 }
0128
0129 static void unix_stream_bpf_check_needs_rebuild(struct proto *ops)
0130 {
0131 if (unlikely(ops != smp_load_acquire(&unix_stream_prot_saved))) {
0132 spin_lock_bh(&unix_stream_prot_lock);
0133 if (likely(ops != unix_stream_prot_saved)) {
0134 unix_stream_bpf_rebuild_protos(&unix_stream_bpf_prot, ops);
0135 smp_store_release(&unix_stream_prot_saved, ops);
0136 }
0137 spin_unlock_bh(&unix_stream_prot_lock);
0138 }
0139 }
0140
0141 int unix_dgram_bpf_update_proto(struct sock *sk, struct sk_psock *psock, bool restore)
0142 {
0143 if (sk->sk_type != SOCK_DGRAM)
0144 return -EOPNOTSUPP;
0145
0146 if (restore) {
0147 sk->sk_write_space = psock->saved_write_space;
0148 WRITE_ONCE(sk->sk_prot, psock->sk_proto);
0149 return 0;
0150 }
0151
0152 unix_dgram_bpf_check_needs_rebuild(psock->sk_proto);
0153 WRITE_ONCE(sk->sk_prot, &unix_dgram_bpf_prot);
0154 return 0;
0155 }
0156
0157 int unix_stream_bpf_update_proto(struct sock *sk, struct sk_psock *psock, bool restore)
0158 {
0159 if (restore) {
0160 sk->sk_write_space = psock->saved_write_space;
0161 WRITE_ONCE(sk->sk_prot, psock->sk_proto);
0162 return 0;
0163 }
0164
0165 unix_stream_bpf_check_needs_rebuild(psock->sk_proto);
0166 WRITE_ONCE(sk->sk_prot, &unix_stream_bpf_prot);
0167 return 0;
0168 }
0169
0170 void __init unix_bpf_build_proto(void)
0171 {
0172 unix_dgram_bpf_rebuild_protos(&unix_dgram_bpf_prot, &unix_dgram_proto);
0173 unix_stream_bpf_rebuild_protos(&unix_stream_bpf_prot, &unix_stream_proto);
0174
0175 }
