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Message-ID: <20250702223606.1054680-7-kuniyu@google.com>
Date: Wed, 2 Jul 2025 22:35:18 +0000
From: Kuniyuki Iwashima <kuniyu@...gle.com>
To: "David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>,
Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>
Cc: Simon Horman <horms@...nel.org>, Kuniyuki Iwashima <kuniyu@...gle.com>,
Kuniyuki Iwashima <kuni1840@...il.com>, netdev@...r.kernel.org
Subject: [PATCH v1 net-next 6/7] af_unix: Introduce SO_INQ.
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 <kuniyu@...gle.com>
---
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
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