Re: [PATCH v3 15/25] posix_acl: handle fsid mappings

From: Christoph Hellwig <hch@infradead.org>
To: Christian Brauner <christian.brauner@ubuntu.com>
Cc: "Stéphane Graber" <stgraber@ubuntu.com>,
	"Eric W. Biederman" <ebiederm@xmission.com>,
	"Aleksa Sarai" <cyphar@cyphar.com>,
	"Jann Horn" <jannh@google.com>,
	smbarber@chromium.org,
	"Seth Forshee" <seth.forshee@canonical.com>,
	"Alexander Viro" <viro@zeniv.linux.org.uk>,
	"Alexey Dobriyan" <adobriyan@gmail.com>,
	"Serge Hallyn" <serge@hallyn.com>,
	"James Morris" <jmorris@namei.org>,
	"Kees Cook" <keescook@chromium.org>,
	"Jonathan Corbet" <corbet@lwn.net>,
	"Phil Estes" <estesp@gmail.com>,
	linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	containers@lists.linux-foundation.org,
	linux-security-module@vger.kernel.org, linux-api@vger.kernel.org
Subject: Re: [PATCH v3 15/25] posix_acl: handle fsid mappings
Date: Tue, 18 Feb 2020 14:26:31 -0800	[thread overview]
Message-ID: <20200218222631.GB9535@infradead.org> (raw)
In-Reply-To: <20200218143411.2389182-16-christian.brauner@ubuntu.com>

On Tue, Feb 18, 2020 at 03:34:01PM +0100, Christian Brauner wrote:
> diff --git a/fs/posix_acl.c b/fs/posix_acl.c
> index 249672bf54fe..ed6112c9b804 100644
> --- a/fs/posix_acl.c
> +++ b/fs/posix_acl.c
> @@ -22,6 +22,7 @@
>  #include <linux/xattr.h>
>  #include <linux/export.h>
>  #include <linux/user_namespace.h>
> +#include <linux/fsuidgid.h>
>  
>  static struct posix_acl **acl_by_type(struct inode *inode, int type)
>  {
> @@ -692,12 +693,12 @@ static void posix_acl_fix_xattr_userns(
>  	for (end = entry + count; entry != end; entry++) {
>  		switch(le16_to_cpu(entry->e_tag)) {
>  		case ACL_USER:
> -			uid = make_kuid(from, le32_to_cpu(entry->e_id));
> -			entry->e_id = cpu_to_le32(from_kuid(to, uid));
> +			uid = make_kfsuid(from, le32_to_cpu(entry->e_id));
> +			entry->e_id = cpu_to_le32(from_kfsuid(to, uid));
>  			break;
>  		case ACL_GROUP:
> -			gid = make_kgid(from, le32_to_cpu(entry->e_id));
> -			entry->e_id = cpu_to_le32(from_kgid(to, gid));
> +			gid = make_kfsgid(from, le32_to_cpu(entry->e_id));
> +			entry->e_id = cpu_to_le32(from_kfsgid(to, gid));
>  			break;

Before we touch this code any more it needs to move to the right place.
Poking into ACLs from generic xattr code is a complete layering
violation, and all this needs to be moved so that it is called by
the actual handlers called from the file systems.