ACK/Cmnt: [SRU][X/generic][X/aws][PATCH 1/1] Revert "ovl: modify ovl_permission() to do checks on two inodes"

[Stefan Bader]

On 08.01.20 18:01, Ioanna Alifieraki wrote:
> BugLink: https://bugs.launchpad.net/bugs/1851243
> 
> This commit breaks r/w access to files. Since fixing it requires many
> commits to be backported revert it to avoid risk of regressions.
> For detailed description please look at LP #1851243.
> 
> This reverts commit c8838e8eb196496e55cf40eed602a906b36ef1cc.
> 
> Signed-off-by: Ioanna Alifieraki <ioanna-maria.alifieraki at canonical.com>
Acked-by: Stefan Bader <stefan.bader at canonical.com>
> ---

Since this was found to introduce a regression this sounds appropriate to do.
But since this was part of an upstream stable set I would suggest this also is
brought up with gregkh (so he is at least aware).

For now I would prefix the commit with "UBUNTU: SAUCE:" as it is specific to our
tree (can be done when applying without need for re-submitting).

Finally, for changes targeted for the main kernel, there is no need to ask for
any of the derivatives/backports separately. As those are rebased, any updates
automatically land there once applied to the main kernel. Only of something is
needed in a derivative/backport only, this has to be requested.

-Stefan

>  fs/overlayfs/inode.c | 13 -------------
>  1 file changed, 13 deletions(-)
> 
> diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c
> index 060482e349ef..013d27dc6f58 100644
> --- a/fs/overlayfs/inode.c
> +++ b/fs/overlayfs/inode.c
> @@ -9,7 +9,6 @@
>  
>  #include <linux/fs.h>
>  #include <linux/slab.h>
> -#include <linux/cred.h>
>  #include <linux/xattr.h>
>  #include "overlayfs.h"
>  
> @@ -92,7 +91,6 @@ int ovl_permission(struct inode *inode, int mask)
>  	struct ovl_entry *oe;
>  	struct dentry *alias = NULL;
>  	struct inode *realinode;
> -	const struct cred *old_cred;
>  	struct dentry *realdentry;
>  	bool is_upper;
>  	int err;
> @@ -145,18 +143,7 @@ int ovl_permission(struct inode *inode, int mask)
>  			goto out_dput;
>  	}
>  
> -	/*
> -	 * Check overlay inode with the creds of task and underlying inode
> -	 * with creds of mounter
> -	 */
> -	err = generic_permission(inode, mask);
> -	if (err)
> -		goto out_dput;
> -
> -	old_cred = ovl_override_creds(inode->i_sb);
>  	err = __inode_permission(realinode, mask);
> -	revert_creds(old_cred);
> -
>  out_dput:
>  	dput(alias);
>  	return err;
> 


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