We have an application that uses almost the same code for TCP and AF_UNIX (SOCK_STREAM). TCP can use TCP_INQ, but AF_UNIX doesn't have it and requires an extra syscall, ioctl(SIOCINQ) or getsockopt(SO_MEMINFO) as an alternative. Let's introduce the generic version of TCP_INQ. If SO_INQ is enabled, recvmsg() will put a cmsg of SCM_INQ that contains the exact value of ioctl(SIOCINQ). The cmsg is also included when msg->msg_get_inq is non-zero to make sockets io_uring-friendly. Note that SOCK_CUSTOM_SOCKOPT is flagged only for SOCK_STREAM to override setsockopt() for SOL_SOCKET. By having the flag in struct unix_sock, instead of struct sock, we can later add SO_INQ support for TCP and reuse tcp_sk(sk)->recvmsg_inq. Note also that supporting custom getsockopt() for SOL_SOCKET will need preparation for other SOCK_CUSTOM_SOCKOPT users (UDP, vsock, MPTCP). Signed-off-by: Kuniyuki Iwashima --- arch/alpha/include/uapi/asm/socket.h | 3 ++ arch/mips/include/uapi/asm/socket.h | 3 ++ arch/parisc/include/uapi/asm/socket.h | 3 ++ arch/sparc/include/uapi/asm/socket.h | 3 ++ include/net/af_unix.h | 1 + include/uapi/asm-generic/socket.h | 3 ++ net/unix/af_unix.c | 62 ++++++++++++++++++++++++++- 7 files changed, 76 insertions(+), 2 deletions(-) diff --git a/arch/alpha/include/uapi/asm/socket.h b/arch/alpha/include/uapi/asm/socket.h index 8f1f18adcdb5..5ef57f88df6b 100644 --- a/arch/alpha/include/uapi/asm/socket.h +++ b/arch/alpha/include/uapi/asm/socket.h @@ -152,6 +152,9 @@ #define SO_PASSRIGHTS 83 +#define SO_INQ 84 +#define SCM_INQ SO_INQ + #if !defined(__KERNEL__) #if __BITS_PER_LONG == 64 diff --git a/arch/mips/include/uapi/asm/socket.h b/arch/mips/include/uapi/asm/socket.h index 31ac655b7837..72fb1b006da9 100644 --- a/arch/mips/include/uapi/asm/socket.h +++ b/arch/mips/include/uapi/asm/socket.h @@ -163,6 +163,9 @@ #define SO_PASSRIGHTS 83 +#define SO_INQ 84 +#define SCM_INQ SO_INQ + #if !defined(__KERNEL__) #if __BITS_PER_LONG == 64 diff --git a/arch/parisc/include/uapi/asm/socket.h b/arch/parisc/include/uapi/asm/socket.h index 1f2d5b7a7f5d..c16ec36dfee6 100644 --- a/arch/parisc/include/uapi/asm/socket.h +++ b/arch/parisc/include/uapi/asm/socket.h @@ -144,6 +144,9 @@ #define SO_PASSRIGHTS 0x4051 +#define SO_INQ 0x4052 +#define SCM_INQ SO_INQ + #if !defined(__KERNEL__) #if __BITS_PER_LONG == 64 diff --git a/arch/sparc/include/uapi/asm/socket.h b/arch/sparc/include/uapi/asm/socket.h index adcba7329386..71befa109e1c 100644 --- a/arch/sparc/include/uapi/asm/socket.h +++ b/arch/sparc/include/uapi/asm/socket.h @@ -145,6 +145,9 @@ #define SO_PASSRIGHTS 0x005c +#define SO_INQ 0x005d +#define SCM_INQ SO_INQ + #if !defined(__KERNEL__) diff --git a/include/net/af_unix.h b/include/net/af_unix.h index 603f8cd026e5..34f53dde65ce 100644 --- a/include/net/af_unix.h +++ b/include/net/af_unix.h @@ -48,6 +48,7 @@ struct unix_sock { wait_queue_entry_t peer_wake; struct scm_stat scm_stat; int inq_len; + bool recvmsg_inq; #if IS_ENABLED(CONFIG_AF_UNIX_OOB) struct sk_buff *oob_skb; #endif diff --git a/include/uapi/asm-generic/socket.h b/include/uapi/asm-generic/socket.h index f333a0ac4ee4..53b5a8c002b1 100644 --- a/include/uapi/asm-generic/socket.h +++ b/include/uapi/asm-generic/socket.h @@ -147,6 +147,9 @@ #define SO_PASSRIGHTS 83 +#define SO_INQ 84 +#define SCM_INQ SO_INQ + #if !defined(__KERNEL__) #if __BITS_PER_LONG == 64 || (defined(__x86_64__) && defined(__ILP32__)) diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c index 074edbbfb315..81ef1b7764f7 100644 --- a/net/unix/af_unix.c +++ b/net/unix/af_unix.c @@ -934,6 +934,52 @@ static void unix_show_fdinfo(struct seq_file *m, struct socket *sock) #define unix_show_fdinfo NULL #endif +static bool unix_custom_sockopt(int optname) +{ + switch (optname) { + case SO_INQ: + return true; + default: + return false; + } +} + +static int unix_setsockopt(struct socket *sock, int level, int optname, + sockptr_t optval, unsigned int optlen) +{ + struct unix_sock *u = unix_sk(sock->sk); + struct sock *sk = sock->sk; + int val; + + if (level != SOL_SOCKET) + return -EOPNOTSUPP; + + if (!unix_custom_sockopt(optname)) + return sock_setsockopt(sock, level, optname, optval, optlen); + + if (optlen != sizeof(int)) + return -EINVAL; + + if (copy_from_sockptr(&val, optval, sizeof(val))) + return -EFAULT; + + switch (optname) { + case SO_INQ: + if (sk->sk_type != SOCK_STREAM) + return -EINVAL; + + if (val > 1 || val < 0) + return -EINVAL; + + WRITE_ONCE(u->recvmsg_inq, val); + break; + default: + return -ENOPROTOOPT; + } + + return 0; +} + static const struct proto_ops unix_stream_ops = { .family = PF_UNIX, .owner = THIS_MODULE, @@ -950,6 +996,7 @@ static const struct proto_ops unix_stream_ops = { #endif .listen = unix_listen, .shutdown = unix_shutdown, + .setsockopt = unix_setsockopt, .sendmsg = unix_stream_sendmsg, .recvmsg = unix_stream_recvmsg, .read_skb = unix_stream_read_skb, @@ -1116,6 +1163,7 @@ static int unix_create(struct net *net, struct socket *sock, int protocol, switch (sock->type) { case SOCK_STREAM: + set_bit(SOCK_CUSTOM_SOCKOPT, &sock->flags); sock->ops = &unix_stream_ops; break; /* @@ -1847,6 +1895,9 @@ static int unix_accept(struct socket *sock, struct socket *newsock, skb_free_datagram(sk, skb); wake_up_interruptible(&unix_sk(sk)->peer_wait); + if (tsk->sk_type == SOCK_STREAM) + set_bit(SOCK_CUSTOM_SOCKOPT, &newsock->flags); + /* attach accepted sock to socket */ unix_state_lock(tsk); unix_update_edges(unix_sk(tsk)); @@ -3035,10 +3086,17 @@ static int unix_stream_read_generic(struct unix_stream_read_state *state, } while (size); mutex_unlock(&u->iolock); - if (msg) + if (msg) { scm_recv_unix(sock, msg, &scm, flags); - else + + if (READ_ONCE(u->recvmsg_inq) || msg->msg_get_inq) { + msg->msg_inq = READ_ONCE(u->inq_len); + put_cmsg(msg, SOL_SOCKET, SCM_INQ, + sizeof(msg->msg_inq), &msg->msg_inq); + } + } else { scm_destroy(&scm); + } out: return copied ? : err; } -- 2.50.0.727.gbf7dc18ff4-goog