[PATCH v5 29/42] ioctl: handle idmapped mounts

Christian Brauner
2021-01-12T22:17:27Z

Enable generic ioctls to handle idmapped mounts by passing down the
mount's user namespace. If the initial user namespace is passed nothing
changes so non-idmapped mounts will see identical behavior as before.

Cc: Christoph Hellwig <hch@lst.de>
Cc: David Howells <dhowells@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
---
/* v2 */
patch introduced

/* v3 */
unchanged

/* v4 */
- Serge Hallyn <serge@hallyn.com>:
- Use "mnt_userns" to refer to a vfsmount's userns everywhere to make
terminology consistent.

/* v5 */
base-commit: 7c53f6b671f4aba70ff15e1b05148b10d58c2837

- Christoph Hellwig <hch@lst.de>:
- Use new file_userns_helper().
---
fs/remap_range.c | 7 +++++--
fs/verity/enable.c | 2 +-
2 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/fs/remap_range.c b/fs/remap_range.c
index 29a4a4dbfe12..dc68394ec9a1 100644
--- a/fs/remap_range.c
+++ b/fs/remap_range.c
@@ -432,13 +432,16 @@ EXPORT_SYMBOL(vfs_clone_file_range);
/* Check whether we are allowed to dedupe the destination file */
static bool allow_file_dedupe(struct file *file)
{
+ struct user_namespace *mnt_userns = file_user_ns(file);
+ struct inode *inode = file_inode(file);
+
if (capable(CAP_SYS_ADMIN))
return true;
if (file->f_mode & FMODE_WRITE)
return true;
- if (uid_eq(current_fsuid(), file_inode(file)->i_uid))
+ if (uid_eq(current_fsuid(), i_uid_into_mnt(mnt_userns, inode)))
return true;
- if (!inode_permission(&init_user_ns, file_inode(file), MAY_WRITE))
+ if (!inode_permission(mnt_userns, inode, MAY_WRITE))
return true;
return false;
}
diff --git a/fs/verity/enable.c b/fs/verity/enable.c
index 6809cf8a99b7..9a221e368fa6 100644
--- a/fs/verity/enable.c
+++ b/fs/verity/enable.c
@@ -369,7 +369,7 @@ int fsverity_ioctl_enable(struct file *filp, const void __user *uarg)
* has verity enabled, and to stabilize the data being hashed.
*/

- err = inode_permission(&init_user_ns, inode, MAY_WRITE);
+ err = inode_permission(file_user_ns(filp), inode, MAY_WRITE);
if (err)
return err;

--
2.30.0