Received-SPF: pass (google.com: domain of linux-nfs-owner@vger.kernel.org designates 2620:137:e000::1:18 as permitted sender) client-ip=2620:137:e000::1:18;
From:   Benjamin Coddington <bcodding@redhat.com>
To:     Trond Myklebust <trondmy@hammerspace.com>,
        Anna Schumaker <anna.schumaker@netapp.com>
Cc:     linux-nfs@vger.kernel.org
Subject: [PATCH] NFSv4: use unique client identifiers in network namespaces
Date:   Tue,  8 Feb 2022 15:03:54 -0500
Message-Id: <6e05bf321ff50785360e6c339d111db368e7dfda.1644349990.git.bcodding@redhat.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

In order to differentiate client state, assign a random uuid to the
uniquifing portion of the client identifier when a network namespace is
created.  Containers may still override this value if they wish to maintain
stable client identifiers by writing to /sys/fs/nfs/net/client/identifier,
either by udev rules or other means.

Signed-off-by: Benjamin Coddington <bcodding@redhat.com>
---
 fs/nfs/sysfs.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/fs/nfs/sysfs.c b/fs/nfs/sysfs.c
index 8cb70755e3c9..9b811323fd7f 100644
--- a/fs/nfs/sysfs.c
+++ b/fs/nfs/sysfs.c
@@ -167,6 +167,18 @@ static struct nfs_netns_client *nfs_netns_client_alloc(struct kobject *parent,
 	return NULL;
 }
 
+static void assign_unique_clientid(struct nfs_netns_client *clp)
+{
+	unsigned char client_uuid[16];
+	char *uuid_str = kmalloc(UUID_STRING_LEN + 1, GFP_KERNEL);
+
+	if (uuid_str) {
+		generate_random_uuid(client_uuid);
+		sprintf(uuid_str, "%pU", client_uuid);
+		rcu_assign_pointer(clp->identifier, uuid_str);
+	}
+}
+
 void nfs_netns_sysfs_setup(struct nfs_net *netns, struct net *net)
 {
 	struct nfs_netns_client *clp;
@@ -174,6 +186,8 @@ void nfs_netns_sysfs_setup(struct nfs_net *netns, struct net *net)
 	clp = nfs_netns_client_alloc(nfs_client_kobj, net);
 	if (clp) {
 		netns->nfs_client = clp;
+		if (net != &init_net)
+			assign_unique_clientid(clp);
 		kobject_uevent(&clp->kobject, KOBJ_ADD);
 	}
 }
-- 
2.31.1