From 42d0c4bdf753063b6eec55415003184d3ca24f6e Mon Sep 17 00:00:00 2001
From: Seth Forshee <sforshee@kernel.org>
Date: Thu, 9 Mar 2023 14:39:09 -0600
Subject: [PATCH] filelocks: use mount idmapping for setlease permission check
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: 9caccd41541a ("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>
---
fs/locks.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/fs/locks.c b/fs/locks.c
index d82c4cacdfb9f..df8b26a425248 100644
--- a/fs/locks.c
+++ b/fs/locks.c
@@ -1863,9 +1863,10 @@ int generic_setlease(struct file *filp, long arg, struct file_lock **flp,
void **priv)
{
struct inode *inode = file_inode(filp);
+ vfsuid_t vfsuid = i_uid_into_vfsuid(file_mnt_idmap(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;
--
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