autofs4: translate pids to the right namespace for the daemon

The PID and the TGID of the process triggering 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.

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: Ian Kent <raven@themaw.net>
Cc: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/fs/autofs4/waitq.c b/fs/autofs4/waitq.c
index 3db70dae40d3a842de562c9fb4e26c29f9284239..309ca6bcbb09f9c461e36fc931fbee1ddfb9c022 100644 (file)
--- a/fs/autofs4/waitq.c
+++ b/fs/autofs4/waitq.c
@@ -353,11 +353,23 @@ int autofs4_wait(struct autofs_sb_info *sbi, struct dentry *dentry,
        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 *sbi, struct dentry *dentry,
                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);