Quoting Miklos Szeredi (mik...@szeredi.hu):
> From: Miklos Szeredi <mszer...@suse.cz>
> 
> The PID and the TGID of the process tringgering the mount are sent to the
> daemon.  Currently the global pid values are sent (ones valid in the initial 
> pid
> namespace) but this is wrong if the autofs daemon itself is not running in the
> initial pid namespace.
> 
> So send the pid values that are valid in the namespace of the autofs daemon.
> 
> The namespace to use is taken from the oz_pgrp pid pointer, which was set at
> mount time to the mounting process' pid namespace.
> 
> If the pid translation fails (the triggering process is in an unrelated pid
> namespace) then the automount fails with ENOENT.
> 
> Cc: Serge E. Hallyn <se...@us.ibm.com>

Makes sense.

Acked-by: Serge Hallyn <serge.hal...@canonical.com>

Thanks, Miklos.

> Cc: Eric Biederman <ebied...@xmission.com>
> Signed-off-by: Miklos Szeredi <mszer...@suse.cz>
> ---
>  fs/autofs4/waitq.c |   16 ++++++++++++++--
>  1 file changed, 14 insertions(+), 2 deletions(-)
> 
> --- a/fs/autofs4/waitq.c
> +++ b/fs/autofs4/waitq.c
> @@ -353,11 +353,23 @@ int autofs4_wait(struct autofs_sb_info *
>       struct qstr qstr;
>       char *name;
>       int status, ret, type;
> +     pid_t pid;
> +     pid_t tgid;
>  
>       /* In catatonic mode, we don't wait for nobody */
>       if (sbi->catatonic)
>               return -ENOENT;
>  
> +     /*
> +      * Try translating pids to the namespace of the daemon.
> +      *
> +      * Zero means failure: we are in an unrelated pid namespace.
> +      */
> +     pid = task_pid_nr_ns(current, ns_of_pid(sbi->oz_pgrp));
> +     tgid = task_tgid_nr_ns(current, ns_of_pid(sbi->oz_pgrp));
> +     if (pid == 0 || tgid == 0)
> +             return -ENOENT;
> +
>       if (!dentry->d_inode) {
>               /*
>                * A wait for a negative dentry is invalid for certain
> @@ -423,8 +435,8 @@ int autofs4_wait(struct autofs_sb_info *
>               wq->ino = autofs4_get_ino(sbi);
>               wq->uid = current_uid();
>               wq->gid = current_gid();
> -             wq->pid = current->pid;
> -             wq->tgid = current->tgid;
> +             wq->pid = pid;
> +             wq->tgid = tgid;
>               wq->status = -EINTR; /* Status return if interrupted */
>               wq->wait_ctr = 2;
>               mutex_unlock(&sbi->wq_mutex);
> --
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