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proc: Restrict mounting the proc filesystem

Don't allow mounting the proc filesystem unless the caller has
CAP_SYS_ADMIN rights over the pid namespace.  The principle here is if
you create or have capabilities over it you can mount it, otherwise
you get to live with what other people have mounted.

Andy pointed out that this is needed to prevent users in a user
namespace from remounting proc and specifying different hidepid and gid
options on already existing proc mounts.

Cc: stable@vger.kernel.org
Reported-by: Andy Lutomirski <luto@amacapital.net>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
master
Eric W. Biederman 9 years ago
parent
commit
aee1c13dd0
  1. 3
      fs/proc/root.c

3
fs/proc/root.c

@ -110,7 +110,8 @@ static struct dentry *proc_mount(struct file_system_type *fs_type,
ns = task_active_pid_ns(current);
options = data;
if (!current_user_ns()->may_mount_proc)
if (!current_user_ns()->may_mount_proc ||
!ns_capable(ns->user_ns, CAP_SYS_ADMIN))
return ERR_PTR(-EPERM);
}

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