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