Commit 069d5ac9 authored Sep 30, 2016 by Eric W. Biederman

autofs: Fix automounts by using current_real_cred()->uid



Seth Forshee reports that in 4.8-rcN some automounts are failing
because the requesting the automount changed.

The relevant call path is:
follow_automount()
    ->d_automount
    autofs4_d_automount
       autofs4_mount_wait
           autofs4_wait

In autofs4_wait wq_uid and wq_gid are set to current_uid() and
current_gid respectively.  With follow_automount now overriding creds
uid that we export to userspace changes and that breaks existing
setups.

To remove the regression set wq_uid and wq_gid from
current_real_cred()->uid and current_real_cred()->gid respectively.
This restores the current behavior as current->real_cred is identical
to current->cred except when override creds are used.

Cc: stable@vger.kernel.org
Fixes: aeaa4a79 ("fs: Call d_automount with the filesystems creds")
Reported-by: Seth Forshee <seth.forshee@canonical.com>
Tested-by: Seth Forshee <seth.forshee@canonical.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>

parent d2921684

fs/autofs4/waitq.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -431,8 +431,8 @@ int autofs4_wait(struct autofs_sb_info *sbi,
		memcpy(&wq->name, &qstr, sizeof(struct qstr));
		wq->dev = autofs4_get_dev(sbi);
		wq->ino = autofs4_get_ino(sbi);
		wq->uid = current_uid();
		wq->gid = current_gid();
		wq->uid = current_real_cred()->uid;
		wq->gid = current_real_cred()->gid;
		wq->pid = pid;
		wq->tgid = tgid;
		wq->status = -EINTR; /* Status return if interrupted */

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