netdev - Re: [PATCH v1 net-next 6/7] af_unix: Introduce SO

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <686a81f1ec754_3aa65429440@willemb.c.googlers.com.notmuch>
Date: Sun, 06 Jul 2025 10:02:25 -0400
From: Willem de Bruijn <willemdebruijn.kernel@...il.com>
To: Kuniyuki Iwashima <kuniyu@...gle.com>, 
 "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: Re: [PATCH v1 net-next 6/7] af_unix: Introduce SO_INQ.

Kuniyuki Iwashima wrote:
> 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>

Reviewed-by: Willem de Bruijn <willemb@...gle.com>

> +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;

Sanity check, but technically not needed as SOCK_CUSTOM_SOCKOPT is
only set for SOCK_STREAM?

> +
> +		if (val > 1 || val < 0)
> +			return -EINVAL;
> +
> +		WRITE_ONCE(u->recvmsg_inq, val);
> +		break;
> +	default:
> +		return -ENOPROTOOPT;
> +	}
> +
> +	return 0;
> +}
> +