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Date: Tue, 6 May 2025 10:24:12 +0200
From: Christian Brauner <brauner@kernel.org>
To: Kuniyuki Iwashima <kuniyu@amazon.com>
Cc: alexander@mihalicyn.com, bluca@debian.org, daan.j.demeyer@gmail.com, 
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Subject: Re: [PATCH RFC v3 04/10] coredump: add coredump socket
Message-ID: <20250506-pilze-wegstecken-1d792c7b79b7@brauner>
References: <20250505-work-coredump-socket-v3-4-e1832f0e1eae@kernel.org>
 <20250505184847.15534-1-kuniyu@amazon.com>
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On Mon, May 05, 2025 at 11:48:43AM -0700, Kuniyuki Iwashima wrote:
> From: Christian Brauner <brauner@kernel.org>
> Date: Mon, 05 May 2025 13:13:42 +0200
> > @@ -801,6 +846,40 @@ void do_coredump(const kernel_siginfo_t *siginfo)
> >  		}
> >  		break;
> >  	}
> > +	case COREDUMP_SOCK: {
> > +		struct file *file __free(fput) = NULL;
> > +#ifdef CONFIG_UNIX
> > +		struct socket *socket;
> > +
> > +		/*
> > +		 * It is possible that the userspace process which is
> > +		 * supposed to handle the coredump and is listening on
> > +		 * the AF_UNIX socket coredumps. Userspace should just
> > +		 * mark itself non dumpable.
> > +		 */
> > +
> > +		retval = sock_create_kern(&init_net, AF_UNIX, SOCK_STREAM, 0, &socket);
> > +		if (retval < 0)
> > +			goto close_fail;
> > +
> > +		file = sock_alloc_file(socket, 0, NULL);
> > +		if (IS_ERR(file)) {
> > +			sock_release(socket);
> > +			retval = PTR_ERR(file);
> > +			goto close_fail;
> > +		}
> > +
> > +		retval = kernel_connect(socket,
> > +					(struct sockaddr *)(&coredump_unix_socket),
> > +					COREDUMP_UNIX_SOCKET_ADDR_SIZE, 0);
> 
> This blocks forever if the listener's accept() queue is full.
> 
> I think we don't want that and should pass O_NONBLOCK.
> 
> To keep the queue clean is userspace responsibility, and we don't
> need to care about a weird user.

That seems fine to me. I've changed that.