linux-kernel - Re: [PATCH v3 15/25] posix

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Message-ID: <20200218222631.GB9535@infradead.org>
Date:   Tue, 18 Feb 2020 14:26:31 -0800
From:   Christoph Hellwig <hch@...radead.org>
To:     Christian Brauner <christian.brauner@...ntu.com>
Cc:     Stéphane Graber <stgraber@...ntu.com>,
        "Eric W. Biederman" <ebiederm@...ssion.com>,
        Aleksa Sarai <cyphar@...har.com>, Jann Horn <jannh@...gle.com>,
        smbarber@...omium.org, Seth Forshee <seth.forshee@...onical.com>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        Alexey Dobriyan <adobriyan@...il.com>,
        Serge Hallyn <serge@...lyn.com>,
        James Morris <jmorris@...ei.org>,
        Kees Cook <keescook@...omium.org>,
        Jonathan Corbet <corbet@....net>,
        Phil Estes <estesp@...il.com>, linux-kernel@...r.kernel.org,
        linux-fsdevel@...r.kernel.org,
        containers@...ts.linux-foundation.org,
        linux-security-module@...r.kernel.org, linux-api@...r.kernel.org
Subject: Re: [PATCH v3 15/25] posix_acl: handle fsid mappings

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.