Unverified Commit cf71eaa1 authored Aug 06, 2024 by Christian Brauner

proc: block mounting on top of /proc/<pid>/fdinfo/*

Entries under /proc/<pid>/fdinfo/* are ephemeral and may go away before
the process dies. As such allowing them to be used as mount points
creates the ability to leak mounts that linger until the process dies
with no ability to unmount them until then. Don't allow using them as
mountpoints.

Link: https://lore.kernel.org/r/20240806-work-procfs-v1-6-fb04e1d09f0c@kernel.org


Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>

parent 74ce2080

fs/proc/fd.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -397,8 +397,8 @@ static struct dentry proc_fdinfo_instantiate(struct dentry dentry,
		inode->i_fop = &proc_fdinfo_file_operations;
		tid_fd_update_inode(task, inode, 0);

		d_set_d_op(dentry, &tid_fd_dentry_operations);
		return d_splice_alias(inode, dentry);
		return proc_splice_unmountable(inode, dentry,
		&tid_fd_dentry_operations);
		}

		static struct dentry *