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filelocks: use mount idmapping for setlease permission check 

commit 42d0c4bdf7 upstream.

A user should be allowed to take out a lease via an idmapped mount if
the fsuid matches the mapped uid of the inode. generic_setlease() is
checking the unmapped inode uid, causing these operations to be denied.

Fix this by comparing against the mapped inode uid instead of the
unmapped uid.

Fixes: 9caccd4154 ("fs: introduce MOUNT_ATTR_IDMAP")
Cc: stable@vger.kernel.org
Signed-off-by: Seth Forshee (DigitalOcean) <sforshee@kernel.org>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Seth Forshee 2023-03-09 14:39:09 -06:00 committed by Greg Kroah-Hartman
parent a8691ec981
commit c20fb060ce
1 changed files with 2 additions and 1 deletions
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3
fs/locks.c
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@ -1862,9 +1862,10 @@ int generic_setlease(struct file *filp, long arg, struct file_lock **flp,
void **priv)
{
struct inode *inode = locks_inode(filp);
vfsuid_t vfsuid = i_uid_into_vfsuid(file_mnt_user_ns(filp), inode);
int error;
if ((!uid_eq(current_fsuid(), inode->i_uid)) && !capable(CAP_LEASE))
if ((!vfsuid_eq_kuid(vfsuid, current_fsuid())) && !capable(CAP_LEASE))
return -EACCES;
if (!S_ISREG(inode->i_mode))
return -EINVAL;