514 lines
12 KiB
C
514 lines
12 KiB
C
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/*
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* Copyright (c) 2008-2010 Sun Microsystems, Inc.
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* Written by Ricardo Correia <Ricardo.M.Correia@Sun.COM>
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*
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* This file is part of the SPL, Solaris Porting Layer.
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* For details, see <http://zfsonlinux.org/>.
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*
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* The SPL is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the
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* Free Software Foundation; either version 2 of the License, or (at your
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* option) any later version.
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*
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* The SPL is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with the SPL. If not, see <http://www.gnu.org/licenses/>.
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*
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* Solaris Porting Layer (SPL) XDR Implementation.
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*/
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#include <linux/string.h>
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#include <sys/kmem.h>
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#include <sys/debug.h>
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#include <sys/types.h>
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#include <sys/sysmacros.h>
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#include <rpc/xdr.h>
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/*
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* SPL's XDR mem implementation.
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*
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* This is used by libnvpair to serialize/deserialize the name-value pair data
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* structures into byte arrays in a well-defined and portable manner.
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*
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* These data structures are used by the DMU/ZFS to flexibly manipulate various
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* information in memory and later serialize it/deserialize it to disk.
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* Examples of usages include the pool configuration, lists of pool and dataset
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* properties, etc.
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*
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* Reference documentation for the XDR representation and XDR operations can be
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* found in RFC 1832 and xdr(3), respectively.
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*
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* === Implementation shortcomings ===
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*
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* It is assumed that the following C types have the following sizes:
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*
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* char/unsigned char: 1 byte
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* short/unsigned short: 2 bytes
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* int/unsigned int: 4 bytes
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* longlong_t/u_longlong_t: 8 bytes
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*
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* The C standard allows these types to be larger (and in the case of ints,
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* shorter), so if that is the case on some compiler/architecture, the build
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* will fail (on purpose).
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*
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* If someone wants to fix the code to work properly on such environments, then:
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*
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* 1) Preconditions should be added to xdrmem_enc functions to make sure the
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* caller doesn't pass arguments which exceed the expected range.
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* 2) Functions which take signed integers should be changed to properly do
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* sign extension.
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* 3) For ints with less than 32 bits, well.. I suspect you'll have bigger
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* problems than this implementation.
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*
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* It is also assumed that:
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*
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* 1) Chars have 8 bits.
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* 2) We can always do 32-bit-aligned int memory accesses and byte-aligned
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* memcpy, memset and memcmp.
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* 3) Arrays passed to xdr_array() are packed and the compiler/architecture
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* supports element-sized-aligned memory accesses.
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* 4) Negative integers are natively stored in two's complement binary
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* representation.
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*
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* No checks are done for the 4 assumptions above, though.
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*
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* === Caller expectations ===
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*
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* Existing documentation does not describe the semantics of XDR operations very
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* well. Therefore, some assumptions about failure semantics will be made and
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* will be described below:
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*
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* 1) If any encoding operation fails (e.g., due to lack of buffer space), the
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* the stream should be considered valid only up to the encoding operation
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* previous to the one that first failed. However, the stream size as returned
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* by xdr_control() cannot be considered to be strictly correct (it may be
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* bigger).
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*
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* Putting it another way, if there is an encoding failure it's undefined
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* whether anything is added to the stream in that operation and therefore
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* neither xdr_control() nor future encoding operations on the same stream can
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* be relied upon to produce correct results.
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*
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* 2) If a decoding operation fails, it's undefined whether anything will be
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* decoded into passed buffers/pointers during that operation, or what the
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* values on those buffers will look like.
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*
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* Future decoding operations on the same stream will also have similar
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* undefined behavior.
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*
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* 3) When the first decoding operation fails it is OK to trust the results of
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* previous decoding operations on the same stream, as long as the caller
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* expects a failure to be possible (e.g. due to end-of-stream).
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*
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* However, this is highly discouraged because the caller should know the
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* stream size and should be coded to expect any decoding failure to be data
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* corruption due to hardware, accidental or even malicious causes, which should
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* be handled gracefully in all cases.
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*
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* In very rare situations where there are strong reasons to believe the data
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* can be trusted to be valid and non-tampered with, then the caller may assume
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* a decoding failure to be a bug (e.g. due to mismatched data types) and may
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* fail non-gracefully.
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*
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* 4) Non-zero padding bytes will cause the decoding operation to fail.
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*
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* 5) Zero bytes on string types will also cause the decoding operation to fail.
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*
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* 6) It is assumed that either the pointer to the stream buffer given by the
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* caller is 32-bit aligned or the architecture supports non-32-bit-aligned int
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* memory accesses.
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*
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* 7) The stream buffer and encoding/decoding buffers/ptrs should not overlap.
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*
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* 8) If a caller passes pointers to non-kernel memory (e.g., pointers to user
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* space or MMIO space), the computer may explode.
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*/
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static struct xdr_ops xdrmem_encode_ops;
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static struct xdr_ops xdrmem_decode_ops;
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void
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xdrmem_create(XDR *xdrs, const caddr_t addr, const uint_t size,
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const enum xdr_op op)
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{
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switch (op) {
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case XDR_ENCODE:
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xdrs->x_ops = &xdrmem_encode_ops;
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break;
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case XDR_DECODE:
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xdrs->x_ops = &xdrmem_decode_ops;
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break;
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default:
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xdrs->x_ops = NULL; /* Let the caller know we failed */
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return;
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}
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xdrs->x_op = op;
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xdrs->x_addr = addr;
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xdrs->x_addr_end = addr + size;
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if (xdrs->x_addr_end < xdrs->x_addr) {
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xdrs->x_ops = NULL;
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}
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}
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EXPORT_SYMBOL(xdrmem_create);
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static bool_t
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xdrmem_control(XDR *xdrs, int req, void *info)
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{
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struct xdr_bytesrec *rec = (struct xdr_bytesrec *)info;
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if (req != XDR_GET_BYTES_AVAIL)
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return (FALSE);
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rec->xc_is_last_record = TRUE; /* always TRUE in xdrmem streams */
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rec->xc_num_avail = xdrs->x_addr_end - xdrs->x_addr;
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return (TRUE);
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}
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static bool_t
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xdrmem_enc_bytes(XDR *xdrs, caddr_t cp, const uint_t cnt)
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{
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uint_t size = roundup(cnt, 4);
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uint_t pad;
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if (size < cnt)
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return (FALSE); /* Integer overflow */
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if (xdrs->x_addr > xdrs->x_addr_end)
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return (FALSE);
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if (xdrs->x_addr_end - xdrs->x_addr < size)
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return (FALSE);
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memcpy(xdrs->x_addr, cp, cnt);
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xdrs->x_addr += cnt;
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pad = size - cnt;
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if (pad > 0) {
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memset(xdrs->x_addr, 0, pad);
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xdrs->x_addr += pad;
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}
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return (TRUE);
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}
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static bool_t
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xdrmem_dec_bytes(XDR *xdrs, caddr_t cp, const uint_t cnt)
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{
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static uint32_t zero = 0;
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uint_t size = roundup(cnt, 4);
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uint_t pad;
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if (size < cnt)
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return (FALSE); /* Integer overflow */
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if (xdrs->x_addr > xdrs->x_addr_end)
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return (FALSE);
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if (xdrs->x_addr_end - xdrs->x_addr < size)
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return (FALSE);
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memcpy(cp, xdrs->x_addr, cnt);
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xdrs->x_addr += cnt;
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pad = size - cnt;
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if (pad > 0) {
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/* An inverted memchr() would be useful here... */
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if (memcmp(&zero, xdrs->x_addr, pad) != 0)
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return (FALSE);
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xdrs->x_addr += pad;
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}
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return (TRUE);
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}
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static bool_t
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xdrmem_enc_uint32(XDR *xdrs, uint32_t val)
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{
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if (xdrs->x_addr + sizeof (uint32_t) > xdrs->x_addr_end)
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return (FALSE);
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*((uint32_t *)xdrs->x_addr) = cpu_to_be32(val);
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xdrs->x_addr += sizeof (uint32_t);
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return (TRUE);
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}
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static bool_t
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xdrmem_dec_uint32(XDR *xdrs, uint32_t *val)
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{
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if (xdrs->x_addr + sizeof (uint32_t) > xdrs->x_addr_end)
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return (FALSE);
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*val = be32_to_cpu(*((uint32_t *)xdrs->x_addr));
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xdrs->x_addr += sizeof (uint32_t);
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return (TRUE);
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}
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static bool_t
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xdrmem_enc_char(XDR *xdrs, char *cp)
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{
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uint32_t val;
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BUILD_BUG_ON(sizeof (char) != 1);
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val = *((unsigned char *) cp);
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return (xdrmem_enc_uint32(xdrs, val));
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}
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static bool_t
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xdrmem_dec_char(XDR *xdrs, char *cp)
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{
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uint32_t val;
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BUILD_BUG_ON(sizeof (char) != 1);
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if (!xdrmem_dec_uint32(xdrs, &val))
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return (FALSE);
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/*
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* If any of the 3 other bytes are non-zero then val will be greater
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* than 0xff and we fail because according to the RFC, this block does
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* not have a char encoded in it.
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*/
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if (val > 0xff)
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return (FALSE);
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*((unsigned char *) cp) = val;
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return (TRUE);
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}
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static bool_t
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xdrmem_enc_ushort(XDR *xdrs, unsigned short *usp)
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{
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BUILD_BUG_ON(sizeof (unsigned short) != 2);
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return (xdrmem_enc_uint32(xdrs, *usp));
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}
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static bool_t
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xdrmem_dec_ushort(XDR *xdrs, unsigned short *usp)
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{
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uint32_t val;
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BUILD_BUG_ON(sizeof (unsigned short) != 2);
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if (!xdrmem_dec_uint32(xdrs, &val))
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return (FALSE);
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/*
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* Short ints are not in the RFC, but we assume similar logic as in
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* xdrmem_dec_char().
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*/
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if (val > 0xffff)
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return (FALSE);
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*usp = val;
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return (TRUE);
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}
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static bool_t
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xdrmem_enc_uint(XDR *xdrs, unsigned *up)
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{
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BUILD_BUG_ON(sizeof (unsigned) != 4);
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return (xdrmem_enc_uint32(xdrs, *up));
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}
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static bool_t
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xdrmem_dec_uint(XDR *xdrs, unsigned *up)
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{
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BUILD_BUG_ON(sizeof (unsigned) != 4);
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return (xdrmem_dec_uint32(xdrs, (uint32_t *)up));
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}
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static bool_t
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xdrmem_enc_ulonglong(XDR *xdrs, u_longlong_t *ullp)
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{
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BUILD_BUG_ON(sizeof (u_longlong_t) != 8);
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if (!xdrmem_enc_uint32(xdrs, *ullp >> 32))
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return (FALSE);
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return (xdrmem_enc_uint32(xdrs, *ullp & 0xffffffff));
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}
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static bool_t
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xdrmem_dec_ulonglong(XDR *xdrs, u_longlong_t *ullp)
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{
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uint32_t low, high;
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BUILD_BUG_ON(sizeof (u_longlong_t) != 8);
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if (!xdrmem_dec_uint32(xdrs, &high))
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return (FALSE);
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if (!xdrmem_dec_uint32(xdrs, &low))
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return (FALSE);
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*ullp = ((u_longlong_t)high << 32) | low;
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return (TRUE);
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}
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static bool_t
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xdr_enc_array(XDR *xdrs, caddr_t *arrp, uint_t *sizep, const uint_t maxsize,
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const uint_t elsize, const xdrproc_t elproc)
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{
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uint_t i;
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caddr_t addr = *arrp;
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if (*sizep > maxsize || *sizep > UINT_MAX / elsize)
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return (FALSE);
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if (!xdrmem_enc_uint(xdrs, sizep))
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return (FALSE);
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|
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for (i = 0; i < *sizep; i++) {
|
||
|
|
if (!elproc(xdrs, addr))
|
||
|
|
return (FALSE);
|
||
|
|
addr += elsize;
|
||
|
|
}
|
||
|
|
|
||
|
|
return (TRUE);
|
||
|
|
}
|
||
|
|
|
||
|
|
static bool_t
|
||
|
|
xdr_dec_array(XDR *xdrs, caddr_t *arrp, uint_t *sizep, const uint_t maxsize,
|
||
|
|
const uint_t elsize, const xdrproc_t elproc)
|
||
|
|
{
|
||
|
|
uint_t i, size;
|
||
|
|
bool_t alloc = FALSE;
|
||
|
|
caddr_t addr;
|
||
|
|
|
||
|
|
if (!xdrmem_dec_uint(xdrs, sizep))
|
||
|
|
return (FALSE);
|
||
|
|
|
||
|
|
size = *sizep;
|
||
|
|
|
||
|
|
if (size > maxsize || size > UINT_MAX / elsize)
|
||
|
|
return (FALSE);
|
||
|
|
|
||
|
|
/*
|
||
|
|
* The Solaris man page says: "If *arrp is NULL when decoding,
|
||
|
|
* xdr_array() allocates memory and *arrp points to it".
|
||
|
|
*/
|
||
|
|
if (*arrp == NULL) {
|
||
|
|
BUILD_BUG_ON(sizeof (uint_t) > sizeof (size_t));
|
||
|
|
|
||
|
|
*arrp = kmem_alloc(size * elsize, KM_NOSLEEP);
|
||
|
|
if (*arrp == NULL)
|
||
|
|
return (FALSE);
|
||
|
|
|
||
|
|
alloc = TRUE;
|
||
|
|
}
|
||
|
|
|
||
|
|
addr = *arrp;
|
||
|
|
|
||
|
|
for (i = 0; i < size; i++) {
|
||
|
|
if (!elproc(xdrs, addr)) {
|
||
|
|
if (alloc)
|
||
|
|
kmem_free(*arrp, size * elsize);
|
||
|
|
return (FALSE);
|
||
|
|
}
|
||
|
|
addr += elsize;
|
||
|
|
}
|
||
|
|
|
||
|
|
return (TRUE);
|
||
|
|
}
|
||
|
|
|
||
|
|
static bool_t
|
||
|
|
xdr_enc_string(XDR *xdrs, char **sp, const uint_t maxsize)
|
||
|
|
{
|
||
|
|
size_t slen = strlen(*sp);
|
||
|
|
uint_t len;
|
||
|
|
|
||
|
|
if (slen > maxsize)
|
||
|
|
return (FALSE);
|
||
|
|
|
||
|
|
len = slen;
|
||
|
|
|
||
|
|
if (!xdrmem_enc_uint(xdrs, &len))
|
||
|
|
return (FALSE);
|
||
|
|
|
||
|
|
return (xdrmem_enc_bytes(xdrs, *sp, len));
|
||
|
|
}
|
||
|
|
|
||
|
|
static bool_t
|
||
|
|
xdr_dec_string(XDR *xdrs, char **sp, const uint_t maxsize)
|
||
|
|
{
|
||
|
|
uint_t size;
|
||
|
|
bool_t alloc = FALSE;
|
||
|
|
|
||
|
|
if (!xdrmem_dec_uint(xdrs, &size))
|
||
|
|
return (FALSE);
|
||
|
|
|
||
|
|
if (size > maxsize || size > UINT_MAX - 1)
|
||
|
|
return (FALSE);
|
||
|
|
|
||
|
|
/*
|
||
|
|
* Solaris man page: "If *sp is NULL when decoding, xdr_string()
|
||
|
|
* allocates memory and *sp points to it".
|
||
|
|
*/
|
||
|
|
if (*sp == NULL) {
|
||
|
|
BUILD_BUG_ON(sizeof (uint_t) > sizeof (size_t));
|
||
|
|
|
||
|
|
*sp = kmem_alloc(size + 1, KM_NOSLEEP);
|
||
|
|
if (*sp == NULL)
|
||
|
|
return (FALSE);
|
||
|
|
|
||
|
|
alloc = TRUE;
|
||
|
|
}
|
||
|
|
|
||
|
|
if (!xdrmem_dec_bytes(xdrs, *sp, size))
|
||
|
|
goto fail;
|
||
|
|
|
||
|
|
if (memchr(*sp, 0, size) != NULL)
|
||
|
|
goto fail;
|
||
|
|
|
||
|
|
(*sp)[size] = '\0';
|
||
|
|
|
||
|
|
return (TRUE);
|
||
|
|
|
||
|
|
fail:
|
||
|
|
if (alloc)
|
||
|
|
kmem_free(*sp, size + 1);
|
||
|
|
|
||
|
|
return (FALSE);
|
||
|
|
}
|
||
|
|
|
||
|
|
static struct xdr_ops xdrmem_encode_ops = {
|
||
|
|
.xdr_control = xdrmem_control,
|
||
|
|
.xdr_char = xdrmem_enc_char,
|
||
|
|
.xdr_u_short = xdrmem_enc_ushort,
|
||
|
|
.xdr_u_int = xdrmem_enc_uint,
|
||
|
|
.xdr_u_longlong_t = xdrmem_enc_ulonglong,
|
||
|
|
.xdr_opaque = xdrmem_enc_bytes,
|
||
|
|
.xdr_string = xdr_enc_string,
|
||
|
|
.xdr_array = xdr_enc_array
|
||
|
|
};
|
||
|
|
|
||
|
|
static struct xdr_ops xdrmem_decode_ops = {
|
||
|
|
.xdr_control = xdrmem_control,
|
||
|
|
.xdr_char = xdrmem_dec_char,
|
||
|
|
.xdr_u_short = xdrmem_dec_ushort,
|
||
|
|
.xdr_u_int = xdrmem_dec_uint,
|
||
|
|
.xdr_u_longlong_t = xdrmem_dec_ulonglong,
|
||
|
|
.xdr_opaque = xdrmem_dec_bytes,
|
||
|
|
.xdr_string = xdr_dec_string,
|
||
|
|
.xdr_array = xdr_dec_array
|
||
|
|
};
|