NFSD: Add an xdr_stream-based decoder for NFSv2/3 ACLs
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
diff --git a/fs/nfs_common/nfsacl.c b/fs/nfs_common/nfsacl.c
index d056ad2..79c563c 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);