Commit 754f8cb7 authored by Vivek Goyal's avatar Vivek Goyal Committed by Miklos Szeredi

ovl: do not require mounter to have MAY_WRITE on lower

Now we have two levels of checks in ovl_permission(). overlay inode
is checked with the creds of task while underlying inode is checked
with the creds of mounter.

Looks like mounter does not have to have WRITE access to files on lower/.
So remove the MAY_WRITE from access mask for checks on underlying
lower inode.

This means task should still have the MAY_WRITE permission on lower
inode and mounter is not required to have MAY_WRITE.

It also solves the problem of read only NFS mounts being used as lower.
If __inode_permission(lower_inode, MAY_WRITE) is called on read only
NFS, it fails. By resetting MAY_WRITE, check succeeds and case of
read only NFS shold work with overlay without having to specify any
special mount options (default permission).
Signed-off-by: default avatarVivek Goyal <vgoyal@redhat.com>
Signed-off-by: default avatarMiklos Szeredi <mszeredi@redhat.com>
parent 1175b6b8
...@@ -184,6 +184,8 @@ int ovl_permission(struct inode *inode, int mask) ...@@ -184,6 +184,8 @@ int ovl_permission(struct inode *inode, int mask)
return err; return err;
old_cred = ovl_override_creds(inode->i_sb); old_cred = ovl_override_creds(inode->i_sb);
if (!is_upper)
mask &= ~(MAY_WRITE | MAY_APPEND);
err = __inode_permission(realinode, mask); err = __inode_permission(realinode, mask);
revert_creds(old_cred); revert_creds(old_cred);
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment