[RFC PATCH v4 10/12] nfs - objlayout use namespace if not executing in init namespace

[Ian Kent <raven@themaw.net>]

From: Ian Kent <ikent@redhat.com>

If the caller is running within a container then execute the usermode
helper callback within the init namespace of the container.

Signed-off-by: Ian Kent <ikent@redhat.com>
Cc: Benjamin Coddington <bcodding@redhat.com>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Cc: J. Bruce Fields <bfields@fieldses.org>
Cc: David Howells <dhowells@redhat.com>
Cc: Trond Myklebust <trond.myklebust@primarydata.com>
Cc: Oleg Nesterov <onestero@redhat.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Jeff Layton <jeff.layton@primarydata.com>
---
 fs/nfs/objlayout/objlayout.c |    7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/fs/nfs/objlayout/objlayout.c b/fs/nfs/objlayout/objlayout.c
index 919efd4..00c9a34 100644
--- a/fs/nfs/objlayout/objlayout.c
+++ b/fs/nfs/objlayout/objlayout.c
@@ -599,9 +599,14 @@ static int __objlayout_upcall(struct __auto_login *login)
 		"PATH=/sbin:/usr/sbin:/bin:/usr/bin",
 		NULL
 	};
+	unsigned int umh_flags = UMH_WAIT_PROC;
 	char *argv[8];
 	int ret;
 
+	/* If running within a container use the container namespace */
+	if (current->nsproxy->net_ns != &init_net)
+		umh_flags |= UMH_USE_NS;
+
 	if (unlikely(!osd_login_prog[0])) {
 		dprintk("%s: osd_login_prog is disabled\n", __func__);
 		return -EACCES;
@@ -620,7 +625,7 @@ static int __objlayout_upcall(struct __auto_login *login)
 	argv[6] = login->systemid_hex;
 	argv[7] = NULL;
 
-	ret = call_usermodehelper(argv[0], argv, envp, UMH_WAIT_PROC);
+	ret = call_usermodehelper(argv[0], argv, envp, umh_flags);
 	/*
 	 * Disable the upcall mechanism if we're getting an ENOENT or
 	 * EACCES error. The admin can re-enable it on the fly by using