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Diffstat (limited to 'module/spl/spl-xdr.c')
| -rw-r--r-- | module/spl/spl-xdr.c | 515 |
1 files changed, 515 insertions, 0 deletions
diff --git a/module/spl/spl-xdr.c b/module/spl/spl-xdr.c new file mode 100644 index 000000000..2cc3e2a03 --- /dev/null +++ b/module/spl/spl-xdr.c @@ -0,0 +1,515 @@ +/* + * Copyright (c) 2008-2010 Sun Microsystems, Inc. + * Written by Ricardo Correia <[email protected]> + * + * This file is part of the SPL, Solaris Porting Layer. + * For details, see <http://zfsonlinux.org/>. + * + * 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 <http://www.gnu.org/licenses/>. + * + * Solaris Porting Layer (SPL) XDR Implementation. + */ + +#include <linux/string.h> +#include <sys/kmem.h> +#include <sys/debug.h> +#include <sys/types.h> +#include <sys/sysmacros.h> +#include <rpc/xdr.h> + +/* + * 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 struct xdr_ops xdrmem_encode_ops; +static struct xdr_ops xdrmem_decode_ops; + +typedef int bool_t; + +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 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 +}; 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