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From: Al Viro <viro@zeniv.linux.org.uk>
To: Miklos Szeredi <mszeredi@redhat.com>
Cc: linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH 01/12] vfs: allow unprivileged whiteout creation
Date: Wed, 13 May 2020 20:12:06 +0100	[thread overview]
Message-ID: <20200513191206.GW23230@ZenIV.linux.org.uk> (raw)
In-Reply-To: <20200505095915.11275-2-mszeredi@redhat.com>

On Tue, May 05, 2020 at 11:59:04AM +0200, Miklos Szeredi wrote:
> Whiteouts, unlike real device node should not require privileges to create.
> 
> The general concern with device nodes is that opening them can have side
> effects.  The kernel already avoids zero major (see
> Documentation/admin-guide/devices.txt).  To be on the safe side the patch
> explicitly forbids registering a char device with 0/0 number (see
> cdev_add()).
> 
> This guarantees that a non-O_PATH open on a whiteout will fail with ENODEV;
> i.e. it won't have any side effect.

Humm...  one question:

>  int vfs_whiteout(struct inode *dir, struct dentry *dentry)
>  {
> -	int error = may_create(dir, dentry);
> -	if (error)
> -		return error;
> -
> -	if (!dir->i_op->mknod)
> -		return -EPERM;
> -
> -	return dir->i_op->mknod(dir, dentry,
> -				S_IFCHR | WHITEOUT_MODE, WHITEOUT_DEV);
> +	return vfs_mknod(dir, dentry, S_IFCHR | WHITEOUT_MODE, WHITEOUT_DEV);
>  }

why do we still need to export it?  I mean, it looks like
a static inline fodder.

  reply	other threads:[~2020-05-13 19:12 UTC|newest]

Thread overview: 35+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-05  9:59 [PATCH 00/12] vfs patch queue Miklos Szeredi
2020-05-05  9:59 ` [PATCH 01/12] vfs: allow unprivileged whiteout creation Miklos Szeredi
2020-05-13 19:12   ` Al Viro [this message]
2020-05-05  9:59 ` [PATCH 02/12] aio: fix async fsync creds Miklos Szeredi
2020-05-13 10:01   ` Christoph Hellwig
2020-05-05  9:59 ` [PATCH 03/12] proc/mounts: add cursor Miklos Szeredi
2020-05-13 19:33   ` Al Viro
2020-05-05  9:59 ` [PATCH 04/12] utimensat: AT_EMPTY_PATH support Miklos Szeredi
2020-05-13 10:02   ` Christoph Hellwig
2020-05-05  9:59 ` [PATCH 05/12] f*xattr: allow O_PATH descriptors Miklos Szeredi
2020-05-13 10:04   ` Christoph Hellwig
2020-05-14  8:02     ` Miklos Szeredi
2020-05-14 13:01       ` Miklos Szeredi
2020-05-05  9:59 ` [PATCH 06/12] uapi: deprecate STATX_ALL Miklos Szeredi
2020-05-13 10:04   ` Christoph Hellwig
2020-05-05  9:59 ` [PATCH 07/12] statx: don't clear STATX_ATIME on SB_RDONLY Miklos Szeredi
2020-05-13 10:04   ` Christoph Hellwig
2020-05-05  9:59 ` [PATCH 08/12] statx: add mount ID Miklos Szeredi
2020-05-13 10:05   ` Christoph Hellwig
2020-05-05  9:59 ` [PATCH 09/12] statx: add mount_root Miklos Szeredi
2020-05-05 14:24   ` J . Bruce Fields
2020-05-13 10:05   ` Christoph Hellwig
2020-05-05  9:59 ` [PATCH 10/12] vfs: don't parse forbidden flags Miklos Szeredi
2020-05-13 10:06   ` Christoph Hellwig
2020-05-05  9:59 ` [PATCH 11/12] vfs: don't parse "posixacl" option Miklos Szeredi
2020-05-13 10:07   ` Christoph Hellwig
2020-05-05  9:59 ` [PATCH 12/12] vfs: don't parse "silent" option Miklos Szeredi
2020-05-13 10:07   ` Christoph Hellwig
2020-05-13  7:45 ` [13/12 PATCH] vfs: add faccessat2 syscall Miklos Szeredi
2020-05-13 10:09   ` Christoph Hellwig
2020-05-13  7:47 ` [PATCH 00/12] vfs patch queue Miklos Szeredi
2020-05-13 19:48   ` Al Viro
2020-05-14 11:46     ` Miklos Szeredi
2020-05-14 14:55     ` Miklos Szeredi
2020-05-14 15:10       ` Al Viro

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