linux-ext4 - Re: [PATCH 5/5] reiserfs: preserve i_mode if __reiserfs_set

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Message-ID: <20170717164554.GD22195@quack2.suse.cz>
Date:   Mon, 17 Jul 2017 18:45:54 +0200
From:   Jan Kara <jack@...e.cz>
To:     Ernesto A. Fernández 
        <ernesto.mnd.fernandez@...il.com>
Cc:     Jan Kara <jack@...e.com>, Theodore Ts'o <tytso@....edu>,
        Andreas Dilger <adilger.kernel@...ger.ca>,
        Dave Kleikamp <shaggy@...nel.org>, linux-ext4@...r.kernel.org,
        jfs-discussion@...ts.sourceforge.net,
        reiserfs-devel@...r.kernel.org
Subject: Re: [PATCH 5/5] reiserfs: preserve i_mode if __reiserfs_set_acl()
 fails

On Wed 12-07-17 06:56:04, Ernesto A. Fernández wrote:
> When changing a file's acl mask, __reiserfs_set_acl() will first set the
> group bits of i_mode to the value of the mask, and only then set the
> actual extended attribute representing the new acl.
> 
> If the second part fails (due to lack of space, for example) and the file
> had no acl attribute to begin with, the system will from now on assume
> that the mask permission bits are actual group permission bits, potentially
> granting access to the wrong users.
> 
> Prevent this by only changing the inode mode after the acl has been set.
> Also make reiserfs_xattr_set_handle() return -ENODATA only in case of
> actual error, and return 0 when requested deletion of a nonexistent acl.
> This is more consistent with the behaviour of other *_xattr_set()
> functions and makes the patch simpler.
> 
> Signed-off-by: Ernesto A. Fernández <ernesto.mnd.fernandez@...il.com>

Thanks for the patch!  I have rebased this onto my tree and merged the
resulting patch (attached).

								Honza

> ---
>  fs/reiserfs/xattr.c     |  4 ++++
>  fs/reiserfs/xattr_acl.c | 25 +++++++++----------------
>  2 files changed, 13 insertions(+), 16 deletions(-)
> 
> diff --git a/fs/reiserfs/xattr.c b/fs/reiserfs/xattr.c
> index e87aa21..936a57a 100644
> --- a/fs/reiserfs/xattr.c
> +++ b/fs/reiserfs/xattr.c
> @@ -513,6 +513,10 @@ reiserfs_xattr_set_handle(struct reiserfs_transaction_handle *th,
>  
>  	if (!buffer) {
>  		err = lookup_and_delete_xattr(inode, name);
> +		if (flags & XATTR_REPLACE)
> +			return err;
> +		if (err == -ENODATA)
> +			err = 0;
>  		return err;
>  	}
>  
> diff --git a/fs/reiserfs/xattr_acl.c b/fs/reiserfs/xattr_acl.c
> index 3d2256a..c02e5ac 100644
> --- a/fs/reiserfs/xattr_acl.c
> +++ b/fs/reiserfs/xattr_acl.c
> @@ -237,14 +237,17 @@ __reiserfs_set_acl(struct reiserfs_transaction_handle *th, struct inode *inode,
>  	void *value = NULL;
>  	size_t size = 0;
>  	int error;
> +	int update_mode = 0;
> +	umode_t mode = inode->i_mode;
>  
>  	switch (type) {
>  	case ACL_TYPE_ACCESS:
>  		name = XATTR_NAME_POSIX_ACL_ACCESS;
>  		if (acl) {
> -			error = posix_acl_update_mode(inode, &inode->i_mode, &acl);
> +			error = posix_acl_update_mode(inode, &mode, &acl);
>  			if (error)
>  				return error;
> +			update_mode = 1;
>  		}
>  		break;
>  	case ACL_TYPE_DEFAULT:
> @@ -264,25 +267,15 @@ __reiserfs_set_acl(struct reiserfs_transaction_handle *th, struct inode *inode,
>  
>  	error = reiserfs_xattr_set_handle(th, inode, name, value, size, 0);
>  
> -	/*
> -	 * Ensure that the inode gets dirtied if we're only using
> -	 * the mode bits and an old ACL didn't exist. We don't need
> -	 * to check if the inode is hashed here since we won't get
> -	 * called by reiserfs_inherit_default_acl().
> -	 */
> -	if (error == -ENODATA) {
> -		error = 0;
> -		if (type == ACL_TYPE_ACCESS) {
> +	kfree(value);
> +	if (!error) {
> +		set_cached_acl(inode, type, acl);
> +		if (update_mode) {
> +			inode->i_mode = mode;
>  			inode->i_ctime = current_time(inode);
>  			mark_inode_dirty(inode);
>  		}
>  	}
> -
> -	kfree(value);
> -
> -	if (!error)
> -		set_cached_acl(inode, type, acl);
> -
>  	return error;
>  }
>  
> -- 
> 2.1.4
> 
> 
-- 
Jan Kara <jack@...e.com>
SUSE Labs, CR

View attachment "0001-reiserfs-preserve-i_mode-if-__reiserfs_set_acl-fails.patch" of type "text/x-patch" (2176 bytes)