nfsd: add support for upcall version 2

Version 2 upcalls will allow the nfsd to include a hash of the kerberos
principal string in the Cld_Create upcall.  If a principal is present in
the svc_cred, then the hash will be included in the Cld_Create upcall.
We attempt to use the svc_cred.cr_raw_principal (which is returned by
gssproxy) first, and then fall back to using the svc_cred.cr_principal
(which is returned by both gssproxy and rpc.svcgssd).  Upon a subsequent
restart, the hash will be returned in the Cld_Gracestart downcall and
stored in the reclaim_str_hashtbl so it can be used when handling
reclaim opens.
Signed-off-by: Scott Mayhew <smayhew@redhat.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

fs/nfsd/nfs4state.c

@@ -6887,7 +6887,8 @@ nfs4_has_reclaimed_state(struct xdr_netobj name, struct nfsd_net *nn)
  * will be freed in nfs4_remove_reclaim_record in the normal case).
  */
 struct nfs4_client_reclaim *
-nfs4_client_to_reclaim(struct xdr_netobj name, struct nfsd_net *nn)
+nfs4_client_to_reclaim(struct xdr_netobj name, struct xdr_netobj princhash,
+		struct nfsd_net *nn)
 {
 	unsigned int strhashval;
 	struct nfs4_client_reclaim *crp;
@@ -6900,6 +6901,8 @@ nfs4_client_to_reclaim(struct xdr_netobj name, struct nfsd_net *nn)
 		list_add(&crp->cr_strhash, &nn->reclaim_str_hashtbl[strhashval]);
 		crp->cr_name.data = name.data;
 		crp->cr_name.len = name.len;
+		crp->cr_princhash.data = princhash.data;
+		crp->cr_princhash.len = princhash.len;
 		crp->cr_clp = NULL;
 		nn->reclaim_str_hashtbl_size++;
 	}
@@ -6911,6 +6914,7 @@ nfs4_remove_reclaim_record(struct nfs4_client_reclaim *crp, struct nfsd_net *nn)
 {
 	list_del(&crp->cr_strhash);
 	kfree(crp->cr_name.data);
+	kfree(crp->cr_princhash.data);
 	kfree(crp);
 	nn->reclaim_str_hashtbl_size--;
 }

fs/nfsd/state.h

@@ -378,6 +378,7 @@ struct nfs4_client_reclaim {
 	struct list_head	cr_strhash;	/* hash by cr_name */
 	struct nfs4_client	*cr_clp;	/* pointer to associated clp */
 	struct xdr_netobj	cr_name;	/* recovery dir name */
+	struct xdr_netobj	cr_princhash;
 };
 
 /* A reasonable value for REPLAY_ISIZE was estimated as follows:  
@@ -645,7 +646,7 @@ extern void nfsd4_shutdown_callback(struct nfs4_client *);
 extern void nfsd4_shutdown_copy(struct nfs4_client *clp);
 extern void nfsd4_prepare_cb_recall(struct nfs4_delegation *dp);
 extern struct nfs4_client_reclaim *nfs4_client_to_reclaim(struct xdr_netobj name,
-							struct nfsd_net *nn);
+				struct xdr_netobj princhash, struct nfsd_net *nn);
 extern bool nfs4_has_reclaimed_state(struct xdr_netobj name, struct nfsd_net *nn);
 
 struct nfs4_file *find_file(struct knfsd_fh *fh);

include/uapi/linux/nfsd/cld.h

@@ -26,11 +26,15 @@
 #include <linux/types.h>
 
 /* latest upcall version available */
-#define CLD_UPCALL_VERSION 1
+#define CLD_UPCALL_VERSION 2
 
 /* defined by RFC3530 */
 #define NFS4_OPAQUE_LIMIT 1024
 
+#ifndef SHA256_DIGEST_SIZE
+#define SHA256_DIGEST_SIZE      32
+#endif
+
 enum cld_command {
 	Cld_Create,		/* create a record for this cm_id */
 	Cld_Remove,		/* remove record of this cm_id */
@@ -46,6 +50,17 @@ struct cld_name {
 	unsigned char	cn_id[NFS4_OPAQUE_LIMIT];	/* client-provided */
 } __attribute__((packed));
 
+/* sha256 hash of the kerberos principal */
+struct cld_princhash {
+	__u8		cp_len;				/* length of cp_data */
+	unsigned char	cp_data[SHA256_DIGEST_SIZE];	/* hash of principal */
+} __attribute__((packed));
+
+struct cld_clntinfo {
+	struct cld_name		cc_name;
+	struct cld_princhash	cc_princhash;
+} __attribute__((packed));
+
 /* message struct for communication with userspace */
 struct cld_msg {
 	__u8		cm_vers;		/* upcall version */
@@ -59,6 +74,19 @@ struct cld_msg {
 	} __attribute__((packed)) cm_u;
 } __attribute__((packed));
 
+/* version 2 message can include hash of kerberos principal */
+struct cld_msg_v2 {
+	__u8		cm_vers;		/* upcall version */
+	__u8		cm_cmd;			/* upcall command */
+	__s16		cm_status;		/* return code */
+	__u32		cm_xid;			/* transaction id */
+	union {
+		struct cld_name	cm_name;
+		__u8		cm_version;	/* for getting max version */
+		struct cld_clntinfo cm_clntinfo; /* name & princ hash */
+	} __attribute__((packed)) cm_u;
+} __attribute__((packed));
+
 struct cld_msg_hdr {
 	__u8		cm_vers;		/* upcall version */
 	__u8		cm_cmd;			/* upcall command */