3 files changed, 53 insertions, 3 deletions
diff --git a/fs/nfs_common/Makefile b/fs/nfs_common/Makefile
index fa82f5aaa6d9..119c75ab9fd0 100644
--- a/fs/nfs_common/Makefile
+++ b/fs/nfs_common/Makefile
@@ -7,4 +7,4 @@ obj-$(CONFIG_NFS_ACL_SUPPORT) += nfs_acl.o
 nfs_acl-objs := nfsacl.o
 
 obj-$(CONFIG_GRACE_PERIOD) += grace.o
-obj-$(CONFIG_GRACE_PERIOD) += nfs_ssc.o
+obj-$(CONFIG_NFS_V4_2_SSC_HELPER) += nfs_ssc.o
diff --git a/fs/nfs_common/nfs_ssc.c b/fs/nfs_common/nfs_ssc.c
index f43bbb373913..7c1509e968c8 100644
--- a/fs/nfs_common/nfs_ssc.c
+++ b/fs/nfs_common/nfs_ssc.c
@@ -1,7 +1,5 @@
 // SPDX-License-Identifier: GPL-2.0-only
 /*
- * fs/nfs_common/nfs_ssc_comm.c
- *
  * Helper for knfsd's SSC to access ops in NFS client modules
  *
  * Author: Dai Ngo <[email protected]>
diff --git a/fs/nfs_common/nfsacl.c b/fs/nfs_common/nfsacl.c
index d056ad2fdefd..79c563c1a5e8 100644
--- a/fs/nfs_common/nfsacl.c
+++ b/fs/nfs_common/nfsacl.c
@@ -295,3 +295,55 @@ int nfsacl_decode(struct xdr_buf *buf, unsigned int base, unsigned int *aclcnt,
 		   nfsacl_desc.desc.array_len;
 }
 EXPORT_SYMBOL_GPL(nfsacl_decode);
+
+/**
+ * nfs_stream_decode_acl - Decode an NFSv3 ACL
+ *
+ * @xdr: an xdr_stream positioned at an encoded ACL
+ * @aclcnt: OUT: count of ACEs in decoded posix_acl
+ * @pacl: OUT: a dynamically-allocated buffer containing the decoded posix_acl
+ *
+ * Return values:
+ *   %false: The encoded ACL is not valid
+ *   %true: @pacl contains a decoded ACL, and @xdr is advanced
+ *
+ * On a successful return, caller must release *pacl using posix_acl_release().
+ */
+bool nfs_stream_decode_acl(struct xdr_stream *xdr, unsigned int *aclcnt,
+			   struct posix_acl **pacl)
+{
+	const size_t elem_size = XDR_UNIT * 3;
+	struct nfsacl_decode_desc nfsacl_desc = {
+		.desc = {
+			.elem_size = elem_size,
+			.xcode = pacl ? xdr_nfsace_decode : NULL,
+		},
+	};
+	unsigned int base;
+	u32 entries;
+
+	if (xdr_stream_decode_u32(xdr, &entries) < 0)
+		return false;
+	if (entries > NFS_ACL_MAX_ENTRIES)
+		return false;
+
+	base = xdr_stream_pos(xdr);
+	if (!xdr_inline_decode(xdr, XDR_UNIT + elem_size * entries))
+		return false;
+	nfsacl_desc.desc.array_maxlen = entries;
+	if (xdr_decode_array2(xdr->buf, base, &nfsacl_desc.desc))
+		return false;
+
+	if (pacl) {
+		if (entries != nfsacl_desc.desc.array_len ||
+		    posix_acl_from_nfsacl(nfsacl_desc.acl) != 0) {
+			posix_acl_release(nfsacl_desc.acl);
+			return false;
+		}
+		*pacl = nfsacl_desc.acl;
+	}
+	if (aclcnt)
+		*aclcnt = entries;
+	return true;
+}
+EXPORT_SYMBOL_GPL(nfs_stream_decode_acl);