NFSD: Add helper to decode OPEN's open_claim4 argument

[ Upstream commit 1708e50b0145f393acbec9e319bdf0e33f765d25 ]

Refactor for clarity.

Note that op_fname is the only instance of an NFSv4 filename stored
in a struct xdr_netobj. Convert it to a u32/char * pair so that the
new nfsd4_decode_filename() helper can be used.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

fs/nfsd/nfs4proc.c

@@ -257,8 +257,8 @@ do_open_lookup(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate, stru
 		 * in NFSv4 as in v3 except EXCLUSIVE4_1.
 		 */
 		current->fs->umask = open->op_umask;
-		status = do_nfsd_create(rqstp, current_fh, open->op_fname.data,
+		status = do_nfsd_create(rqstp, current_fh, open->op_fname,
-					open->op_fname.len, &open->op_iattr,
+					open->op_fnamelen, &open->op_iattr,
 					*resfh, open->op_createmode,
 					(u32 *)open->op_verf.data,
 					&open->op_truncate, &open->op_created);
@@ -283,7 +283,7 @@ do_open_lookup(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate, stru
 		 * a chance to an acquire a delegation if appropriate.
 		 */
 		status = nfsd_lookup(rqstp, current_fh,
-				     open->op_fname.data, open->op_fname.len, *resfh);
+				     open->op_fname, open->op_fnamelen, *resfh);
 	if (status)
 		goto out;
 	status = nfsd_check_obj_isreg(*resfh);
@@ -360,7 +360,7 @@ nfsd4_open(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
 	bool reclaim = false;
 
 	dprintk("NFSD: nfsd4_open filename %.*s op_openowner %p\n",
-		(int)open->op_fname.len, open->op_fname.data,
+		(int)open->op_fnamelen, open->op_fname,
 		open->op_openowner);
 
 	/* This check required by spec. */

fs/nfsd/nfs4xdr.c

@@ -1072,6 +1072,55 @@ static __be32 nfsd4_decode_share_deny(struct nfsd4_compoundargs *argp, u32 *x)
 	return nfs_ok;
 }
 
+static __be32
+nfsd4_decode_open_claim4(struct nfsd4_compoundargs *argp,
+			 struct nfsd4_open *open)
+{
+	__be32 status;
+
+	if (xdr_stream_decode_u32(argp->xdr, &open->op_claim_type) < 0)
+		return nfserr_bad_xdr;
+	switch (open->op_claim_type) {
+	case NFS4_OPEN_CLAIM_NULL:
+	case NFS4_OPEN_CLAIM_DELEGATE_PREV:
+		status = nfsd4_decode_component4(argp, &open->op_fname,
+						 &open->op_fnamelen);
+		if (status)
+			return status;
+		break;
+	case NFS4_OPEN_CLAIM_PREVIOUS:
+		if (xdr_stream_decode_u32(argp->xdr, &open->op_delegate_type) < 0)
+			return nfserr_bad_xdr;
+		break;
+	case NFS4_OPEN_CLAIM_DELEGATE_CUR:
+		status = nfsd4_decode_stateid4(argp, &open->op_delegate_stateid);
+		if (status)
+			return status;
+		status = nfsd4_decode_component4(argp, &open->op_fname,
+						 &open->op_fnamelen);
+		if (status)
+			return status;
+		break;
+	case NFS4_OPEN_CLAIM_FH:
+	case NFS4_OPEN_CLAIM_DELEG_PREV_FH:
+		if (argp->minorversion < 1)
+			return nfserr_bad_xdr;
+		/* void */
+		break;
+	case NFS4_OPEN_CLAIM_DELEG_CUR_FH:
+		if (argp->minorversion < 1)
+			return nfserr_bad_xdr;
+		status = nfsd4_decode_stateid4(argp, &open->op_delegate_stateid);
+		if (status)
+			return status;
+		break;
+	default:
+		return nfserr_bad_xdr;
+	}
+
+	return nfs_ok;
+}
+
 static __be32
 nfsd4_decode_open(struct nfsd4_compoundargs *argp, struct nfsd4_open *open)
 {
@@ -1102,51 +1151,7 @@ nfsd4_decode_open(struct nfsd4_compoundargs *argp, struct nfsd4_open *open)
 	status = nfsd4_decode_openflag4(argp, open);
 	if (status)
 		return status;
-
+	status = nfsd4_decode_open_claim4(argp, open);
-	/* open_claim */
-	READ_BUF(4);
-	open->op_claim_type = be32_to_cpup(p++);
-	switch (open->op_claim_type) {
-	case NFS4_OPEN_CLAIM_NULL:
-	case NFS4_OPEN_CLAIM_DELEGATE_PREV:
-		READ_BUF(4);
-		open->op_fname.len = be32_to_cpup(p++);
-		READ_BUF(open->op_fname.len);
-		SAVEMEM(open->op_fname.data, open->op_fname.len);
-		if ((status = check_filename(open->op_fname.data, open->op_fname.len)))
-			return status;
-		break;
-	case NFS4_OPEN_CLAIM_PREVIOUS:
-		READ_BUF(4);
-		open->op_delegate_type = be32_to_cpup(p++);
-		break;
-	case NFS4_OPEN_CLAIM_DELEGATE_CUR:
-		status = nfsd4_decode_stateid(argp, &open->op_delegate_stateid);
-		if (status)
-			return status;
-		READ_BUF(4);
-		open->op_fname.len = be32_to_cpup(p++);
-		READ_BUF(open->op_fname.len);
-		SAVEMEM(open->op_fname.data, open->op_fname.len);
-		if ((status = check_filename(open->op_fname.data, open->op_fname.len)))
-			return status;
-		break;
-	case NFS4_OPEN_CLAIM_FH:
-	case NFS4_OPEN_CLAIM_DELEG_PREV_FH:
-		if (argp->minorversion < 1)
-			goto xdr_error;
-		/* void */
-		break;
-	case NFS4_OPEN_CLAIM_DELEG_CUR_FH:
-		if (argp->minorversion < 1)
-			goto xdr_error;
-		status = nfsd4_decode_stateid(argp, &open->op_delegate_stateid);
-		if (status)
-			return status;
-		break;
-	default:
-		goto xdr_error;
-	}
 
 	DECODE_TAIL;
 }

fs/nfsd/xdr4.h

@@ -252,7 +252,8 @@ struct nfsd4_listxattrs {
 
 struct nfsd4_open {
 	u32		op_claim_type;      /* request */
-	struct xdr_netobj op_fname;	    /* request - everything but CLAIM_PREV */
+	u32		op_fnamelen;
+	char *		op_fname;	    /* request - everything but CLAIM_PREV */
 	u32		op_delegate_type;   /* request - CLAIM_PREV only */
 	stateid_t       op_delegate_stateid; /* request - response */
 	u32		op_why_no_deleg;    /* response - DELEG_NONE_EXT only */