fs: port ->setattr() to pass mnt_idmap

Convert to struct mnt_idmap.

Last cycle we merged the necessary infrastructure in
256c8aed2b42 ("fs: introduce dedicated idmap type for mounts").
This is just the conversion to struct mnt_idmap.

Currently we still pass around the plain namespace that was attached to a
mount. This is in general pretty convenient but it makes it easy to
conflate namespaces that are relevant on the filesystem with namespaces
that are relevent on the mount level. Especially for non-vfs developers
without detailed knowledge in this area this can be a potential source for
bugs.

Once the conversion to struct mnt_idmap is done all helpers down to the
really low-level helpers will take a struct mnt_idmap argument instead of
two namespace arguments. This way it becomes impossible to conflate the two
eliminating the possibility of any bugs. All of the vfs and all filesystems
only operate on struct mnt_idmap.

Acked-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>

4 files changed, 10 insertions, 10 deletions

diff --git a/fs/proc/base.c b/fs/proc/base.c
index 9e479d7d202b..92166c33395d 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -685,7 +685,7 @@ static bool proc_fd_access_allowed(struct inode *inode)
 	return allowed;
 }
 
-int proc_setattr(struct user_namespace *mnt_userns, struct dentry *dentry,
+int proc_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
 		 struct iattr *attr)
 {
 	int error;
@@ -694,11 +694,11 @@ int proc_setattr(struct user_namespace *mnt_userns, struct dentry *dentry,
 	if (attr->ia_valid & ATTR_MODE)
 		return -EPERM;
 
-	error = setattr_prepare(&init_user_ns, dentry, attr);
+	error = setattr_prepare(&nop_mnt_idmap, dentry, attr);
 	if (error)
 		return error;
 
-	setattr_copy(&init_user_ns, inode, attr);
+	setattr_copy(&nop_mnt_idmap, inode, attr);
 	mark_inode_dirty(inode);
 	return 0;
 }
diff --git a/fs/proc/generic.c b/fs/proc/generic.c
index 587b91d9d998..4464ad6a2283 100644
--- a/fs/proc/generic.c
+++ b/fs/proc/generic.c
@@ -115,18 +115,18 @@ static bool pde_subdir_insert(struct proc_dir_entry *dir,
 	return true;
 }
 
-static int proc_notify_change(struct user_namespace *mnt_userns,
+static int proc_notify_change(struct mnt_idmap *idmap,
 			      struct dentry *dentry, struct iattr *iattr)
 {
 	struct inode *inode = d_inode(dentry);
 	struct proc_dir_entry *de = PDE(inode);
 	int error;
 
-	error = setattr_prepare(&init_user_ns, dentry, iattr);
+	error = setattr_prepare(&nop_mnt_idmap, dentry, iattr);
 	if (error)
 		return error;
 
-	setattr_copy(&init_user_ns, inode, iattr);
+	setattr_copy(&nop_mnt_idmap, inode, iattr);
 	mark_inode_dirty(inode);
 
 	proc_set_user(de, inode->i_uid, inode->i_gid);
diff --git a/fs/proc/internal.h b/fs/proc/internal.h
index b701d0207edf..6eb921670fc6 100644
--- a/fs/proc/internal.h
+++ b/fs/proc/internal.h
@@ -164,7 +164,7 @@ extern int proc_pid_statm(struct seq_file *, struct pid_namespace *,
 extern const struct dentry_operations pid_dentry_operations;
 extern int pid_getattr(struct user_namespace *, const struct path *,
 		       struct kstat *, u32, unsigned int);
-extern int proc_setattr(struct user_namespace *, struct dentry *,
+extern int proc_setattr(struct mnt_idmap *, struct dentry *,
 			struct iattr *);
 extern void proc_pid_evict_inode(struct proc_inode *);
 extern struct inode *proc_pid_make_inode(struct super_block *, struct task_struct *, umode_t);
diff --git a/fs/proc/proc_sysctl.c b/fs/proc/proc_sysctl.c
index 48f2d60bd78a..daba911972ec 100644
--- a/fs/proc/proc_sysctl.c
+++ b/fs/proc/proc_sysctl.c
@@ -827,7 +827,7 @@ static int proc_sys_permission(struct user_namespace *mnt_userns,
 	return error;
 }
 
-static int proc_sys_setattr(struct user_namespace *mnt_userns,
+static int proc_sys_setattr(struct mnt_idmap *idmap,
 			    struct dentry *dentry, struct iattr *attr)
 {
 	struct inode *inode = d_inode(dentry);
@@ -836,11 +836,11 @@ static int proc_sys_setattr(struct user_namespace *mnt_userns,
 	if (attr->ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID))
 		return -EPERM;
 
-	error = setattr_prepare(&init_user_ns, dentry, attr);
+	error = setattr_prepare(&nop_mnt_idmap, dentry, attr);
 	if (error)
 		return error;
 
-	setattr_copy(&init_user_ns, inode, attr);
+	setattr_copy(&nop_mnt_idmap, inode, attr);
 	mark_inode_dirty(inode);
 	return 0;
 }