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 <[e-mail]>
Signed-off-by: J. Bruce Fields <[e-mail]>

fs/nfsd/nfs4recover.c

···
 };
 
 static const struct nfsd4_client_tracking_ops nfsd4_cld_tracking_ops;
+static const struct nfsd4_client_tracking_ops nfsd4_cld_tracking_ops_v2;
 
 /* Globals */
 static char user_recovery_dirname[PATH_MAX] = "/var/lib/nfs/v4recovery";
···
 		const char *dname, int len, struct nfsd_net *nn)
 {
 	struct xdr_netobj name;
+	struct xdr_netobj princhash = { .len = 0, .data = NULL };
 	struct nfs4_client_reclaim *crp;
 
 	name.data = kmemdup(dname, len, GFP_KERNEL);
···
 		return;
 	}
 	name.len = len;
-	crp = nfs4_client_to_reclaim(name, nn);
+	crp = nfs4_client_to_reclaim(name, princhash, nn);
 	if (!crp) {
 		kfree(name.data);
 		return;
···
 load_recdir(struct dentry *parent, struct dentry *child, struct nfsd_net *nn)
 {
 	struct xdr_netobj name;
+	struct xdr_netobj princhash = { .len = 0, .data = NULL };
 
 	if (child->d_name.len != HEXDIR_LEN - 1) {
 		printk("%s: illegal name %pd in recovery directory\n",
···
 		goto out;
 	}
 	name.len = HEXDIR_LEN;
-	if (!nfs4_client_to_reclaim(name, nn))
+	if (!nfs4_client_to_reclaim(name, princhash, nn))
 		kfree(name.data);
 out:
 	return 0;
···
 	struct list_head	 cn_list;
 	unsigned int		 cn_xid;
 	bool			 cn_has_legacy;
+	struct crypto_shash	*cn_tfm;
 };
 
 struct cld_upcall {
···
 	union {
 		struct cld_msg_hdr	 cu_hdr;
 		struct cld_msg		 cu_msg;
+		struct cld_msg_v2	 cu_msg_v2;
 	} cu_u;
 };
 
···
 }
 
 static ssize_t
-__cld_pipe_inprogress_downcall(const struct cld_msg __user *cmsg,
+__cld_pipe_inprogress_downcall(const struct cld_msg_v2 __user *cmsg,
 		struct nfsd_net *nn)
 {
-	uint8_t cmd;
-	struct xdr_netobj name;
+	uint8_t cmd, princhashlen;
+	struct xdr_netobj name, princhash = { .len = 0, .data = NULL };
 	uint16_t namelen;
 	struct cld_net *cn = nn->cld_net;
 
···
 		return -EFAULT;
 	}
 	if (cmd == Cld_GraceStart) {
-		if (get_user(namelen, &cmsg->cm_u.cm_name.cn_len))
-			return -EFAULT;
-		name.data = memdup_user(&cmsg->cm_u.cm_name.cn_id, namelen);
-		if (IS_ERR_OR_NULL(name.data))
-			return -EFAULT;
-		name.len = namelen;
+		if (nn->client_tracking_ops->version >= 2) {
+			const struct cld_clntinfo __user *ci;
+
+			ci = &cmsg->cm_u.cm_clntinfo;
+			if (get_user(namelen, &ci->cc_name.cn_len))
+				return -EFAULT;
+			name.data = memdup_user(&ci->cc_name.cn_id, namelen);
+			if (IS_ERR_OR_NULL(name.data))
+				return -EFAULT;
+			name.len = namelen;
+			get_user(princhashlen, &ci->cc_princhash.cp_len);
+			if (princhashlen > 0) {
+				princhash.data = memdup_user(
+						&ci->cc_princhash.cp_data,
+						princhashlen);
+				if (IS_ERR_OR_NULL(princhash.data))
+					return -EFAULT;
+				princhash.len = princhashlen;
+			} else
+				princhash.len = 0;
+		} else {
+			const struct cld_name __user *cnm;
+
+			cnm = &cmsg->cm_u.cm_name;
+			if (get_user(namelen, &cnm->cn_len))
+				return -EFAULT;
+			name.data = memdup_user(&cnm->cn_id, namelen);
+			if (IS_ERR_OR_NULL(name.data))
+				return -EFAULT;
+			name.len = namelen;
+		}
 		if (name.len > 5 && memcmp(name.data, "hash:", 5) == 0) {
 			name.len = name.len - 5;
 			memmove(name.data, name.data + 5, name.len);
 			cn->cn_has_legacy = true;
 		}
-		if (!nfs4_client_to_reclaim(name, nn)) {
+		if (!nfs4_client_to_reclaim(name, princhash, nn)) {
 			kfree(name.data);
+			kfree(princhash.data);
 			return -EFAULT;
 		}
 		return nn->client_tracking_ops->msglen;
···
 {
 	struct cld_upcall *tmp, *cup;
 	struct cld_msg_hdr __user *hdr = (struct cld_msg_hdr __user *)src;
-	struct cld_msg __user *cmsg = (struct cld_msg __user *)src;
+	struct cld_msg_v2 __user *cmsg = (struct cld_msg_v2 __user *)src;
 	uint32_t xid;
 	struct nfsd_net *nn = net_generic(file_inode(filp)->i_sb->s_fs_info,
 						nfsd_net_id);
···
 	if (status == -EINPROGRESS)
 		return __cld_pipe_inprogress_downcall(cmsg, nn);
 
-	if (copy_from_user(&cup->cu_u.cu_msg, src, mlen) != 0)
+	if (copy_from_user(&cup->cu_u.cu_msg_v2, src, mlen) != 0)
 		return -EFAULT;
 
 	complete(&cup->cu_done);
···
 
 	nfsd4_cld_unregister_net(net, cn->cn_pipe);
 	rpc_destroy_pipe_data(cn->cn_pipe);
+	if (cn->cn_tfm)
+		crypto_free_shash(cn->cn_tfm);
 	kfree(nn->cld_net);
 	nn->cld_net = NULL;
 }
···
 	if (ret)
 		printk(KERN_ERR "NFSD: Unable to create client "
 				"record on stable storage: %d\n", ret);
+}
+
+/* Ask daemon to create a new record */
+static void
+nfsd4_cld_create_v2(struct nfs4_client *clp)
+{
+	int ret;
+	struct cld_upcall *cup;
+	struct nfsd_net *nn = net_generic(clp->net, nfsd_net_id);
+	struct cld_net *cn = nn->cld_net;
+	struct cld_msg_v2 *cmsg;
+	struct crypto_shash *tfm = cn->cn_tfm;
+	struct xdr_netobj cksum;
+	char *principal = NULL;
+	SHASH_DESC_ON_STACK(desc, tfm);
+
+	/* Don't upcall if it's already stored */
+	if (test_bit(NFSD4_CLIENT_STABLE, &clp->cl_flags))
+		return;
+
+	cup = alloc_cld_upcall(nn);
+	if (!cup) {
+		ret = -ENOMEM;
+		goto out_err;
+	}
+
+	cmsg = &cup->cu_u.cu_msg_v2;
+	cmsg->cm_cmd = Cld_Create;
+	cmsg->cm_u.cm_clntinfo.cc_name.cn_len = clp->cl_name.len;
+	memcpy(cmsg->cm_u.cm_clntinfo.cc_name.cn_id, clp->cl_name.data,
+			clp->cl_name.len);
+	if (clp->cl_cred.cr_raw_principal)
+		principal = clp->cl_cred.cr_raw_principal;
+	else if (clp->cl_cred.cr_principal)
+		principal = clp->cl_cred.cr_principal;
+	if (principal) {
+		desc->tfm = tfm;
+		cksum.len = crypto_shash_digestsize(tfm);
+		cksum.data = kmalloc(cksum.len, GFP_KERNEL);
+		if (cksum.data == NULL) {
+			ret = -ENOMEM;
+			goto out;
+		}
+		ret = crypto_shash_digest(desc, principal, strlen(principal),
+					  cksum.data);
+		shash_desc_zero(desc);
+		if (ret) {
+			kfree(cksum.data);
+			goto out;
+		}
+		cmsg->cm_u.cm_clntinfo.cc_princhash.cp_len = cksum.len;
+		memcpy(cmsg->cm_u.cm_clntinfo.cc_princhash.cp_data,
+		       cksum.data, cksum.len);
+		kfree(cksum.data);
+	} else
+		cmsg->cm_u.cm_clntinfo.cc_princhash.cp_len = 0;
+
+	ret = cld_pipe_upcall(cn->cn_pipe, cmsg);
+	if (!ret) {
+		ret = cmsg->cm_status;
+		set_bit(NFSD4_CLIENT_STABLE, &clp->cl_flags);
+	}
+
+out:
+	free_cld_upcall(cup);
+out_err:
+	if (ret)
+		pr_err("NFSD: Unable to create client record on stable storage: %d\n",
+				ret);
 }
 
 /* Ask daemon to create a new record */
···
 	}
 	return -ENOENT;
 found:
+	crp->cr_clp = clp;
+	return 0;
+}
+
+static int
+nfsd4_cld_check_v2(struct nfs4_client *clp)
+{
+	struct nfs4_client_reclaim *crp;
+	struct nfsd_net *nn = net_generic(clp->net, nfsd_net_id);
+	struct cld_net *cn = nn->cld_net;
+	int status;
+	char dname[HEXDIR_LEN];
+	struct xdr_netobj name;
+	struct crypto_shash *tfm = cn->cn_tfm;
+	struct xdr_netobj cksum;
+	char *principal = NULL;
+	SHASH_DESC_ON_STACK(desc, tfm);
+
+	/* did we already find that this client is stable? */
+	if (test_bit(NFSD4_CLIENT_STABLE, &clp->cl_flags))
+		return 0;
+
+	/* look for it in the reclaim hashtable otherwise */
+	crp = nfsd4_find_reclaim_client(clp->cl_name, nn);
+	if (crp)
+		goto found;
+
+	if (cn->cn_has_legacy) {
+		status = nfs4_make_rec_clidname(dname, &clp->cl_name);
+		if (status)
+			return -ENOENT;
+
+		name.data = kmemdup(dname, HEXDIR_LEN, GFP_KERNEL);
+		if (!name.data) {
+			dprintk("%s: failed to allocate memory for name.data\n",
+					__func__);
+			return -ENOENT;
+		}
+		name.len = HEXDIR_LEN;
+		crp = nfsd4_find_reclaim_client(name, nn);
+		kfree(name.data);
+		if (crp)
+			goto found;
+
+	}
+	return -ENOENT;
+found:
+	if (crp->cr_princhash.len) {
+		if (clp->cl_cred.cr_raw_principal)
+			principal = clp->cl_cred.cr_raw_principal;
+		else if (clp->cl_cred.cr_principal)
+			principal = clp->cl_cred.cr_principal;
+		if (principal == NULL)
+			return -ENOENT;
+		desc->tfm = tfm;
+		cksum.len = crypto_shash_digestsize(tfm);
+		cksum.data = kmalloc(cksum.len, GFP_KERNEL);
+		if (cksum.data == NULL)
+			return -ENOENT;
+		status = crypto_shash_digest(desc, principal, strlen(principal),
+					     cksum.data);
+		shash_desc_zero(desc);
+		if (status) {
+			kfree(cksum.data);
+			return -ENOENT;
+		}
+		if (memcmp(crp->cr_princhash.data, cksum.data,
+				crp->cr_princhash.len)) {
+			kfree(cksum.data);
+			return -ENOENT;
+		}
+		kfree(cksum.data);
+	}
 	crp->cr_clp = clp;
 	return 0;
 }
···
 		case 1:
 			nn->client_tracking_ops = &nfsd4_cld_tracking_ops;
 			break;
+		case 2:
+			nn->client_tracking_ops = &nfsd4_cld_tracking_ops_v2;
+			break;
 		default:
 			break;
 		}
···
 	status = __nfsd4_init_cld_pipe(net);
 	if (status)
 		goto err_shutdown;
+	nn->cld_net->cn_tfm = crypto_alloc_shash("sha256", 0, 0);
+	if (IS_ERR(nn->cld_net->cn_tfm)) {
+		status = PTR_ERR(nn->cld_net->cn_tfm);
+		goto err_remove;
+	}
 
 	/*
 	 * rpc pipe upcalls take 30 seconds to time out, so we don't want to
···
 	.grace_done	= nfsd4_cld_grace_done,
 	.version	= 1,
 	.msglen		= sizeof(struct cld_msg),
+};
+
+/* v2 create/check ops include the principal, if available */
+static const struct nfsd4_client_tracking_ops nfsd4_cld_tracking_ops_v2 = {
+	.init		= nfsd4_cld_tracking_init,
+	.exit		= nfsd4_cld_tracking_exit,
+	.create		= nfsd4_cld_create_v2,
+	.remove		= nfsd4_cld_remove,
+	.check		= nfsd4_cld_check_v2,
+	.grace_done	= nfsd4_cld_grace_done,
+	.version	= 2,
+	.msglen		= sizeof(struct cld_msg_v2),
 };
 
 /* upcall via usermodehelper */

fs/nfsd/nfs4state.c

···
  * 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;
···
 		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++;
 	}
···
 {
 	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

···
 	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:  
···
 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

···
 #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 */
···
 	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 */
···
 		__s64		cm_gracetime;	/* grace period start time */
 		struct cld_name	cm_name;
 		__u8		cm_version;	/* for getting max version */
+	} __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));