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From: Florian Weimer <fw@deneb.enyo.de>
To: Mark Wielaard <mark@klomp.org>
Cc: Josh Triplett <josh@joshtriplett.org>,
	io-uring@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	linux-kernel@vger.kernel.org, mtk.manpages@gmail.com,
	Alexander Viro <viro@zeniv.linux.org.uk>,
	Arnd Bergmann <arnd@arndb.de>, Jens Axboe <axboe@kernel.dk>,
	Aleksa Sarai <cyphar@cyphar.com>,
	linux-man@vger.kernel.org
Subject: Re: [PATCH v5 3/3] fs: pipe2: Support O_SPECIFIC_FD
Date: Wed, 22 Apr 2020 17:44:38 +0200	[thread overview]
Message-ID: <877dy7ikyh.fsf@mid.deneb.enyo.de> (raw)
In-Reply-To: <2bb2e92c688b97247f644fe8220054d6c6b66b65.1587531463.git.josh@joshtriplett.org> (Josh Triplett's message of "Tue, 21 Apr 2020 22:20:20 -0700")

* Josh Triplett:

> This allows the caller of pipe2 to specify one or both file descriptors
> rather than having them automatically use the lowest available file
> descriptor. The caller can specify either file descriptor as -1 to
> allow that file descriptor to use the lowest available.
>
> Signed-off-by: Josh Triplett <josh@joshtriplett.org>
> ---
>  fs/pipe.c | 16 ++++++++++++----
>  1 file changed, 12 insertions(+), 4 deletions(-)
>
> diff --git a/fs/pipe.c b/fs/pipe.c
> index 16fb72e9abf7..4681a0d1d587 100644
> --- a/fs/pipe.c
> +++ b/fs/pipe.c
> @@ -936,19 +936,19 @@ static int __do_pipe_flags(int *fd, struct file **files, int flags)
>  	int error;
>  	int fdw, fdr;
>  
> -	if (flags & ~(O_CLOEXEC | O_NONBLOCK | O_DIRECT))
> +	if (flags & ~(O_CLOEXEC | O_NONBLOCK | O_DIRECT | O_SPECIFIC_FD))
>  		return -EINVAL;
>  
>  	error = create_pipe_files(files, flags);
>  	if (error)
>  		return error;
>  
> -	error = get_unused_fd_flags(flags);
> +	error = get_specific_unused_fd_flags(fd[0], flags);
>  	if (error < 0)
>  		goto err_read_pipe;
>  	fdr = error;
>  
> -	error = get_unused_fd_flags(flags);
> +	error = get_specific_unused_fd_flags(fd[1], flags);
>  	if (error < 0)
>  		goto err_fdr;
>  	fdw = error;
> @@ -969,7 +969,11 @@ static int __do_pipe_flags(int *fd, struct file **files, int flags)
>  int do_pipe_flags(int *fd, int flags)
>  {
>  	struct file *files[2];
> -	int error = __do_pipe_flags(fd, files, flags);
> +	int error;
> +
> +	if (flags & O_SPECIFIC_FD)
> +		return -EINVAL;
> +	error = __do_pipe_flags(fd, files, flags);
>  	if (!error) {
>  		fd_install(fd[0], files[0]);
>  		fd_install(fd[1], files[1]);
> @@ -987,6 +991,10 @@ static int do_pipe2(int __user *fildes, int flags)
>  	int fd[2];
>  	int error;
>  
> +	if (flags & O_SPECIFIC_FD)
> +		if (copy_from_user(fd, fildes, sizeof(fd)))
> +			return -EFAULT;
> +
>  	error = __do_pipe_flags(fd, files, flags);
>  	if (!error) {
>  		if (unlikely(copy_to_user(fildes, fd, sizeof(fd)))) {

Mark, I think this will need (or at least benefit from) some valgrind
changes.

  parent reply	other threads:[~2020-04-22 15:44 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-04-22  5:19 [PATCH v5 0/3] Support userspace-selected fds Josh Triplett
2020-04-22  5:19 ` [PATCH v5 1/3] fs: Support setting a minimum fd for "lowest available fd" allocation Josh Triplett
2020-04-22  6:06   ` Michael Kerrisk (man-pages)
2020-04-23  1:12   ` Dmitry V. Levin
2020-04-23  4:51     ` Josh Triplett
2020-04-23  9:24   ` Arnd Bergmann
2020-04-22  5:20 ` [PATCH v5 2/3] fs: openat2: Extend open_how to allow userspace-selected fds Josh Triplett
2020-04-22  6:06   ` Michael Kerrisk (man-pages)
2020-04-22  7:55     ` Miklos Szeredi
2020-04-23  0:48       ` Josh Triplett
2020-04-23  4:24         ` Miklos Szeredi
2020-04-23  4:42           ` Josh Triplett
2020-04-23  6:04             ` Miklos Szeredi
2020-04-23  7:33               ` Josh Triplett
2020-04-23  7:45                 ` Miklos Szeredi
2020-04-23  7:57                   ` Miklos Szeredi
2020-04-23  9:20                     ` Miklos Szeredi
2020-04-23  9:46                       ` Miklos Szeredi
2020-04-23  8:06                   ` Josh Triplett
2020-04-22  5:20 ` [PATCH v5 3/3] fs: pipe2: Support O_SPECIFIC_FD Josh Triplett
2020-04-22  6:06   ` Michael Kerrisk (man-pages)
2020-04-22 15:44   ` Florian Weimer [this message]
2020-04-23  0:44     ` Josh Triplett
2020-04-22  6:05 ` [PATCH v5 0/3] Support userspace-selected fds Michael Kerrisk (man-pages)

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