fs: port ->permission() 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, 8 insertions, 8 deletions

diff --git a/fs/proc/base.c b/fs/proc/base.c
index aa7ebee00746..5e0e0ccd47aa 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -727,7 +727,7 @@ static bool has_pid_permissions(struct proc_fs_info *fs_info,
 }
 
 
-static int proc_pid_permission(struct user_namespace *mnt_userns,
+static int proc_pid_permission(struct mnt_idmap *idmap,
 			       struct inode *inode, int mask)
 {
 	struct proc_fs_info *fs_info = proc_sb_info(inode->i_sb);
@@ -753,7 +753,7 @@ static int proc_pid_permission(struct user_namespace *mnt_userns,
 
 		return -EPERM;
 	}
-	return generic_permission(&init_user_ns, inode, mask);
+	return generic_permission(&nop_mnt_idmap, inode, mask);
 }
 
 
@@ -3557,7 +3557,7 @@ int proc_pid_readdir(struct file *file, struct dir_context *ctx)
  * This function makes sure that the node is always accessible for members of
  * same thread group.
  */
-static int proc_tid_comm_permission(struct user_namespace *mnt_userns,
+static int proc_tid_comm_permission(struct mnt_idmap *idmap,
 				    struct inode *inode, int mask)
 {
 	bool is_same_tgroup;
@@ -3577,7 +3577,7 @@ static int proc_tid_comm_permission(struct user_namespace *mnt_userns,
 		return 0;
 	}
 
-	return generic_permission(&init_user_ns, inode, mask);
+	return generic_permission(&nop_mnt_idmap, inode, mask);
 }
 
 static const struct inode_operations proc_tid_comm_inode_operations = {
diff --git a/fs/proc/fd.c b/fs/proc/fd.c
index d9bda34c770d..f516c1a68094 100644
--- a/fs/proc/fd.c
+++ b/fs/proc/fd.c
@@ -325,13 +325,13 @@ static struct dentry *proc_lookupfd(struct inode *dir, struct dentry *dentry,
  * /proc/pid/fd needs a special permission handler so that a process can still
  * access /proc/self/fd after it has executed a setuid().
  */
-int proc_fd_permission(struct user_namespace *mnt_userns,
+int proc_fd_permission(struct mnt_idmap *idmap,
 		       struct inode *inode, int mask)
 {
 	struct task_struct *p;
 	int rv;
 
-	rv = generic_permission(&init_user_ns, inode, mask);
+	rv = generic_permission(&nop_mnt_idmap, inode, mask);
 	if (rv == 0)
 		return rv;
 
diff --git a/fs/proc/fd.h b/fs/proc/fd.h
index c5a921a06a0b..7e7265f7e06f 100644
--- a/fs/proc/fd.h
+++ b/fs/proc/fd.h
@@ -10,7 +10,7 @@ extern const struct inode_operations proc_fd_inode_operations;
 extern const struct file_operations proc_fdinfo_operations;
 extern const struct inode_operations proc_fdinfo_inode_operations;
 
-extern int proc_fd_permission(struct user_namespace *mnt_userns,
+extern int proc_fd_permission(struct mnt_idmap *idmap,
 			      struct inode *inode, int mask);
 
 static inline unsigned int proc_fd(struct inode *inode)
diff --git a/fs/proc/proc_sysctl.c b/fs/proc/proc_sysctl.c
index 7d111c46ca75..e89bd8f1368b 100644
--- a/fs/proc/proc_sysctl.c
+++ b/fs/proc/proc_sysctl.c
@@ -798,7 +798,7 @@ out:
 	return 0;
 }
 
-static int proc_sys_permission(struct user_namespace *mnt_userns,
+static int proc_sys_permission(struct mnt_idmap *idmap,
 			       struct inode *inode, int mask)
 {
 	/*