NFSD: Add an xdr_stream-based encoder for NFSv2/3 ACLs

[linux-2.6-microblaze.git] / fs / nfs_common / nfsacl.c

diff --git a/fs/nfs_common/nfsacl.c b/fs/nfs_common/nfsacl.c
index 79c563c..5a5bd85 100644 (file)
--- a/fs/nfs_common/nfsacl.c
+++ b/fs/nfs_common/nfsacl.c
@@ -136,6 +136,77 @@ int nfsacl_encode(struct xdr_buf *buf, unsigned int base, struct inode *inode,
 }
 EXPORT_SYMBOL_GPL(nfsacl_encode);
 
+/**
+ * nfs_stream_encode_acl - Encode an NFSv3 ACL
+ *
+ * @xdr: an xdr_stream positioned to receive an encoded ACL
+ * @inode: inode of file whose ACL this is
+ * @acl: posix_acl to encode
+ * @encode_entries: whether to encode ACEs as well
+ * @typeflag: ACL type: NFS_ACL_DEFAULT or zero
+ *
+ * Return values:
+ *   %false: The ACL could not be encoded
+ *   %true: @xdr is advanced to the next available position
+ */
+bool nfs_stream_encode_acl(struct xdr_stream *xdr, struct inode *inode,
+                          struct posix_acl *acl, int encode_entries,
+                          int typeflag)
+{
+       const size_t elem_size = XDR_UNIT * 3;
+       u32 entries = (acl && acl->a_count) ? max_t(int, acl->a_count, 4) : 0;
+       struct nfsacl_encode_desc nfsacl_desc = {
+               .desc = {
+                       .elem_size = elem_size,
+                       .array_len = encode_entries ? entries : 0,
+                       .xcode = xdr_nfsace_encode,
+               },
+               .acl = acl,
+               .typeflag = typeflag,
+               .uid = inode->i_uid,
+               .gid = inode->i_gid,
+       };
+       struct nfsacl_simple_acl aclbuf;
+       unsigned int base;
+       int err;
+
+       if (entries > NFS_ACL_MAX_ENTRIES)
+               return false;
+       if (xdr_stream_encode_u32(xdr, entries) < 0)
+               return false;
+
+       if (encode_entries && acl && acl->a_count == 3) {
+               struct posix_acl *acl2 = &aclbuf.acl;
+
+               /* Avoid the use of posix_acl_alloc().  nfsacl_encode() is
+                * invoked in contexts where a memory allocation failure is
+                * fatal.  Fortunately this fake ACL is small enough to
+                * construct on the stack. */
+               posix_acl_init(acl2, 4);
+
+               /* Insert entries in canonical order: other orders seem
+                to confuse Solaris VxFS. */
+               acl2->a_entries[0] = acl->a_entries[0];  /* ACL_USER_OBJ */
+               acl2->a_entries[1] = acl->a_entries[1];  /* ACL_GROUP_OBJ */
+               acl2->a_entries[2] = acl->a_entries[1];  /* ACL_MASK */
+               acl2->a_entries[2].e_tag = ACL_MASK;
+               acl2->a_entries[3] = acl->a_entries[2];  /* ACL_OTHER */
+               nfsacl_desc.acl = acl2;
+       }
+
+       base = xdr_stream_pos(xdr);
+       if (!xdr_reserve_space(xdr, XDR_UNIT +
+                              elem_size * nfsacl_desc.desc.array_len))
+               return false;
+       err = xdr_encode_array2(xdr->buf, base, &nfsacl_desc.desc);
+       if (err)
+               return false;
+
+       return true;
+}
+EXPORT_SYMBOL_GPL(nfs_stream_encode_acl);
+
+
 struct nfsacl_decode_desc {
        struct xdr_array2_desc desc;
        unsigned int count;