netdev - Re: [PATCH v5 net-next 5/9] net: Restrict SO_PASS{CRED,PIDFD,SEC} to AF

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Message-ID: <20250609155613.563713-1-kuni1840@gmail.com>
Date: Mon,  9 Jun 2025 08:55:36 -0700
From: Kuniyuki Iwashima <kuni1840@...il.com>
To: bluca@...ian.org
Cc: brauner@...nel.org,
	davem@...emloft.net,
	edumazet@...gle.com,
	horms@...nel.org,
	kuba@...nel.org,
	kuni1840@...il.com,
	kuniyu@...zon.com,
	netdev@...r.kernel.org,
	pabeni@...hat.com,
	willemb@...gle.com
Subject: Re: [PATCH v5 net-next 5/9] net: Restrict SO_PASS{CRED,PIDFD,SEC} to AF_{UNIX,NETLINK,BLUETOOTH}.

From: Luca Boccassi <bluca@...ian.org>
Date: Mon, 09 Jun 2025 12:14:51 +0100
> On Mon, 2025-05-19 at 13:57 -0700, Kuniyuki Iwashima wrote:
> > SCM_CREDENTIALS and SCM_SECURITY can be recv()ed by calling
> > scm_recv() or scm_recv_unix(), and SCM_PIDFD is only used by
> > scm_recv_unix().
> > 
> > scm_recv() is called from AF_NETLINK and AF_BLUETOOTH.
> > 
> > scm_recv_unix() is literally called from AF_UNIX.
> > 
> > Let's restrict SO_PASSCRED and SO_PASSSEC to such sockets and
> > SO_PASSPIDFD to AF_UNIX only.
> > 
> > Later, SOCK_PASS{CRED,PIDFD,SEC} will be moved to struct sock
> > and united with another field.
> > 
> > Signed-off-by: Kuniyuki Iwashima <kuniyu@...zon.com>
> > Reviewed-by: Willem de Bruijn <willemb@...gle.com>
> > ---
> > v3:
> >   * Return -EOPNOTSUPP in getsockopt() too
> >   * Add CONFIG_SECURITY_NETWORK check for SO_PASSSEC
> > 
> > diff --git a/net/core/sock.c b/net/core/sock.c
> > index d7d6d3a8efe5..fd5f9d3873c1 100644
> > --- a/net/core/sock.c
> > +++ b/net/core/sock.c
> > @@ -1221,12 +1221,21 @@ int sk_setsockopt(struct sock *sk, int level,
> > int optname,
> >  		}
> >  		return -EPERM;
> >  	case SO_PASSSEC:
> > +		if (!IS_ENABLED(CONFIG_SECURITY_NETWORK) ||
> > sk_may_scm_recv(sk))
> > +			return -EOPNOTSUPP;
> 
> Hi,
> 
> Was this one meant to be !sk_may_scm_recv(sk) like in getsockopt below
> by any chance?

Oops, but the next patch happened to fix it.

Will try to reproduce it.

> 
> We have a report that this is breaking AF_UNIX sockets with 6.16~rc1:
> 
> [    1.763019] systemd[1]: systemd-journald-dev-log.socket: SO_PASSSEC
> failed: Operation not supported
> [    1.763102] systemd[1]: systemd-journald.socket: SO_PASSSEC failed:
> Operation not supported
> [    1.763121] systemd[1]: systemd-journald.socket: SO_PASSSEC failed:
> Operation not supported
> 
> https://github.com/systemd/systemd/issues/37783