FAILED: patch "[PATCH] filelocks: use mount idmapping for setlease permission check" failed to apply to 5.15-stable tree

The patch below does not apply to the 5.15-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y
git checkout FETCH_HEAD
git cherry-pick -x 42d0c4bdf753063b6eec55415003184d3ca24f6e
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '[email protected]' --subject-prefix 'PATCH 5.15.y' HEAD^..

Possible dependencies:

42d0c4bdf753 ("filelocks: use mount idmapping for setlease permission check")
c65454a94726 ("fs: remove locks_inode")
5970e15dbcfe ("filelock: move file locking definitions to separate header file") 8e1858710d9a ("ceph: avoid use-after-free in ceph_fl_release_lock()")
461ab10ef7e6 ("ceph: switch to vfs_inode_has_locks() to fix file lock bug")
6a518afcc206 ("Merge tag 'fs.acl.rework.v6.2' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/idmapping")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 42d0c4bdf753063b6eec55415003184d3ca24f6e Mon Sep 17 00:00:00 2001
From: Seth Forshee <[email protected]>
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.

index d82c4cacdfb9..df8b26a42524 100644
@@ -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;

From: Seth Forshee <[email protected]>

[ Upstream commit 42d0c4bdf753063b6eec55415003184d3ca24f6e ]

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.

---
 fs/locks.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

index 82a4487e95b3..881fd16905c6 100644
@@ -1901,9 +1901,10 @@ int generic_setlease(struct file *filp, long arg, struct file_lock **flp,
 			void **priv)
 {
 	struct inode *inode = locks_inode(filp);
+	kuid_t uid = i_uid_into_mnt(file_mnt_user_ns(filp), inode);
 	int error;
 
-	if ((!uid_eq(current_fsuid(), inode->i_uid)) && !capable(CAP_LEASE))
+	if ((!uid_eq(current_fsuid(), uid)) && !capable(CAP_LEASE))
 		return -EACCES;
 	if (!S_ISREG(inode->i_mode))
 		return -EINVAL;

2.39.1