15a940bbd8
Allocate in multiples of 16 to avoid adding a few bytes free region the windows bugs upon. * grub-core/mmap/i386/pc/mmap.c (malloc_hook): Likewise.
428 lines
12 KiB
C
428 lines
12 KiB
C
/* drivemap.c - command to manage the BIOS drive mappings. */
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/*
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* GRUB -- GRand Unified Bootloader
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* Copyright (C) 2008, 2009 Free Software Foundation, Inc.
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*
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* GRUB is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* GRUB is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with GRUB. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <grub/extcmd.h>
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#include <grub/dl.h>
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#include <grub/mm.h>
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#include <grub/misc.h>
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#include <grub/disk.h>
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#include <grub/loader.h>
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#include <grub/env.h>
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#include <grub/machine/biosnum.h>
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#include <grub/i18n.h>
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#include <grub/memory.h>
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#include <grub/machine/memory.h>
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GRUB_MOD_LICENSE ("GPLv3+");
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/* Real mode IVT slot (seg:off far pointer) for interrupt 0x13. */
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static grub_uint32_t *const int13slot = (grub_uint32_t *) (4 * 0x13);
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/* Remember to update enum opt_idxs accordingly. */
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static const struct grub_arg_option options[] = {
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/* TRANSLATORS: In this file "mapping" refers to a change GRUB makes so if
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your language doesn't have an equivalent of "mapping" you can
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use the word like "rerouting".
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*/
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{"list", 'l', 0, N_("Show the current mappings."), 0, 0},
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{"reset", 'r', 0, N_("Reset all mappings to the default values."), 0, 0},
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{"swap", 's', 0, N_("Perform both direct and reverse mappings."), 0, 0},
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{0, 0, 0, 0, 0, 0}
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};
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/* Remember to update options[] accordingly. */
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enum opt_idxs
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{
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OPTIDX_LIST = 0,
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OPTIDX_RESET,
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OPTIDX_SWAP,
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};
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/* Realmode far ptr (2 * 16b) to the previous INT13h handler. */
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extern grub_uint32_t grub_drivemap_oldhandler;
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/* The type "void" is used for imported assembly labels, takes no storage and
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serves just to take the address with &label. */
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/* The assembly function to replace the old INT13h handler. It does not follow
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any C callspecs and returns with IRET. */
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extern const void grub_drivemap_handler;
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/* Start of the drive mappings area (space reserved at runtime). */
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extern const void grub_drivemap_mapstart;
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typedef struct drivemap_node
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{
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struct drivemap_node *next;
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grub_uint8_t newdrive;
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grub_uint8_t redirto;
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} drivemap_node_t;
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typedef struct __attribute__ ((packed)) int13map_node
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{
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grub_uint8_t disknum;
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grub_uint8_t mapto;
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} int13map_node_t;
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#define INT13H_OFFSET(x) \
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(((grub_uint8_t *)(x)) - ((grub_uint8_t *)&grub_drivemap_handler))
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static drivemap_node_t *map_head;
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static void *drivemap_hook;
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static int drivemap_mmap;
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/* Puts the specified mapping into the table, replacing an existing mapping
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for newdrive or adding a new one if required. */
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static grub_err_t
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drivemap_set (grub_uint8_t newdrive, grub_uint8_t redirto)
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{
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drivemap_node_t *mapping = 0;
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drivemap_node_t *search = map_head;
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while (search)
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{
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if (search->newdrive == newdrive)
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{
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mapping = search;
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break;
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}
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search = search->next;
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}
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/* Check for pre-existing mappings to modify before creating a new one. */
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if (mapping)
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mapping->redirto = redirto;
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else
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{
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mapping = grub_malloc (sizeof (drivemap_node_t));
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if (! mapping)
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return grub_errno;
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mapping->newdrive = newdrive;
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mapping->redirto = redirto;
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mapping->next = map_head;
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map_head = mapping;
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}
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return GRUB_ERR_NONE;
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}
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/* Removes the mapping for newdrive from the table. If there is no mapping,
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then this function behaves like a no-op on the map. */
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static void
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drivemap_remove (grub_uint8_t newdrive)
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{
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drivemap_node_t *mapping = 0;
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drivemap_node_t *search = map_head;
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drivemap_node_t *previous = 0;
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while (search)
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{
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if (search->newdrive == newdrive)
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{
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mapping = search;
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break;
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}
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previous = search;
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search = search->next;
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}
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if (mapping)
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{
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if (previous)
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previous->next = mapping->next;
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else
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map_head = mapping->next;
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grub_free (mapping);
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}
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}
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/* Given a GRUB-like device name and a convenient location, stores the
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related BIOS disk number. Accepts devices like \((f|h)dN\), with
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0 <= N < 128. */
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static grub_err_t
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tryparse_diskstring (const char *str, grub_uint8_t *output)
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{
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/* Skip opening paren in order to allow both (hd0) and hd0. */
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if (*str == '(')
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str++;
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if ((str[0] == 'f' || str[0] == 'h') && str[1] == 'd')
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{
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grub_uint8_t bios_num = (str[0] == 'h') ? 0x80 : 0x00;
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unsigned long drivenum = grub_strtoul (str + 2, 0, 0);
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if (grub_errno == GRUB_ERR_NONE && drivenum < 128)
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{
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bios_num |= drivenum;
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if (output)
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*output = bios_num;
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return GRUB_ERR_NONE;
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}
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}
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return grub_error (GRUB_ERR_BAD_ARGUMENT, "device format \"%s\" "
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"invalid: must be (f|h)dN, with 0 <= N < 128", str);
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}
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static grub_err_t
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list_mappings (void)
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{
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/* Show: list mappings. */
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if (! map_head)
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{
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grub_puts_ (N_("No drives have been remapped"));
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return GRUB_ERR_NONE;
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}
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/* TRANSLATORS: This is the header of mapping list.
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On the left is how OS will see the disks and
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on the right current GRUB vision. */
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grub_puts_ (N_("OS disk #num ------> GRUB/BIOS device"));
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drivemap_node_t *curnode = map_head;
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while (curnode)
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{
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grub_printf ("%cD #%-3u (0x%02x) %cd%d\n",
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(curnode->newdrive & 0x80) ? 'H' : 'F',
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curnode->newdrive & 0x7F, curnode->newdrive,
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(curnode->redirto & 0x80) ? 'h' : 'f',
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curnode->redirto & 0x7F
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);
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curnode = curnode->next;
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}
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return GRUB_ERR_NONE;
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}
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static grub_err_t
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grub_cmd_drivemap (struct grub_extcmd_context *ctxt, int argc, char **args)
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{
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if (ctxt->state[OPTIDX_LIST].set)
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{
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return list_mappings ();
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}
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else if (ctxt->state[OPTIDX_RESET].set)
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{
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/* Reset: just delete all mappings, freeing their memory. */
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drivemap_node_t *curnode = map_head;
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drivemap_node_t *prevnode = 0;
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while (curnode)
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{
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prevnode = curnode;
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curnode = curnode->next;
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grub_free (prevnode);
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}
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map_head = 0;
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return GRUB_ERR_NONE;
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}
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else if (!ctxt->state[OPTIDX_SWAP].set && argc == 0)
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{
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/* No arguments */
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return list_mappings ();
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}
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/* Neither flag: put mapping. */
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grub_uint8_t mapfrom = 0;
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grub_uint8_t mapto = 0xFF;
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grub_err_t err;
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if (argc != 2)
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return grub_error (GRUB_ERR_BAD_ARGUMENT, N_("two arguments expected"));
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err = tryparse_diskstring (args[0], &mapfrom);
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if (err != GRUB_ERR_NONE)
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return err;
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err = tryparse_diskstring (args[1], &mapto);
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if (err != GRUB_ERR_NONE)
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return err;
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if (mapto == mapfrom)
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{
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/* Reset to default. */
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grub_dprintf ("drivemap", "Removing mapping for %s (%02x)\n",
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args[0], mapfrom);
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drivemap_remove (mapfrom);
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return GRUB_ERR_NONE;
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}
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/* Set the mapping for the disk (overwrites any existing mapping). */
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grub_dprintf ("drivemap", "%s %s (%02x) = %s (%02x)\n",
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ctxt->state[OPTIDX_SWAP].set ? "Swapping" : "Mapping",
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args[1], mapto, args[0], mapfrom);
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err = drivemap_set (mapto, mapfrom);
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/* If -s, perform the reverse mapping too (only if the first was OK). */
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if (ctxt->state[OPTIDX_SWAP].set && err == GRUB_ERR_NONE)
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err = drivemap_set (mapfrom, mapto);
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return err;
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}
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/* Int13h handler installer - reserves conventional memory for the handler,
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copies it over and sets the IVT entry for int13h.
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This code rests on the assumption that GRUB does not activate any kind
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of memory mapping apart from identity paging, since it accesses
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realmode structures by their absolute addresses, like the IVT at 0;
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and transforms a pmode pointer into a rmode seg:off far ptr. */
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static grub_err_t
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install_int13_handler (int noret __attribute__ ((unused)))
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{
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/* Size of the full int13 handler "bundle", including code and map. */
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grub_uint32_t total_size;
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/* Base address of the space reserved for the handler bundle. */
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grub_uint8_t *handler_base = 0;
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/* Address of the map within the deployed bundle. */
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int13map_node_t *handler_map;
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int i;
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int entries = 0;
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drivemap_node_t *curentry = map_head;
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/* Count entries to prepare a contiguous map block. */
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while (curentry)
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{
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entries++;
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curentry = curentry->next;
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}
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if (entries == 0)
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{
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/* No need to install the int13h handler. */
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grub_dprintf ("drivemap", "No drives marked as remapped, not installing "
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"our int13h handler.\n");
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return GRUB_ERR_NONE;
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}
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grub_dprintf ("drivemap", "Installing our int13h handler\n");
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/* Save the pointer to the old handler. */
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grub_drivemap_oldhandler = *int13slot;
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grub_dprintf ("drivemap", "Original int13 handler: %04x:%04x\n",
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(grub_drivemap_oldhandler >> 16) & 0x0ffff,
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grub_drivemap_oldhandler & 0x0ffff);
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/* Find a rmode-segment-aligned zone in conventional memory big
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enough to hold the handler and its data. */
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total_size = INT13H_OFFSET (&grub_drivemap_mapstart)
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+ (entries + 1) * sizeof (int13map_node_t);
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grub_dprintf ("drivemap", "Payload is %u bytes long\n", total_size);
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handler_base = grub_mmap_malign_and_register (16, ALIGN_UP (total_size, 16),
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&drivemap_mmap,
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GRUB_MEMORY_RESERVED,
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GRUB_MMAP_MALLOC_LOW);
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if (! handler_base)
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return grub_error (GRUB_ERR_OUT_OF_MEMORY, "couldn't reserve "
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"memory for the int13h handler");
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/* Copy int13h handler bundle to reserved area. */
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grub_dprintf ("drivemap", "Reserved memory at %p, copying handler\n",
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handler_base);
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grub_memcpy (handler_base, &grub_drivemap_handler,
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INT13H_OFFSET (&grub_drivemap_mapstart));
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/* Copy the mappings to the reserved area. */
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curentry = map_head;
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handler_map = (int13map_node_t *) (handler_base +
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INT13H_OFFSET (&grub_drivemap_mapstart));
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grub_dprintf ("drivemap", "Target map at %p, copying mappings\n", handler_map);
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for (i = 0; i < entries; ++i, curentry = curentry->next)
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{
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handler_map[i].disknum = curentry->newdrive;
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handler_map[i].mapto = curentry->redirto;
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grub_dprintf ("drivemap", "\t#%d: 0x%02x <- 0x%02x\n", i,
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handler_map[i].disknum, handler_map[i].mapto);
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}
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/* Signal end-of-map. */
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handler_map[i].disknum = 0;
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handler_map[i].mapto = 0;
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grub_dprintf ("drivemap", "\t#%d: 0x00 <- 0x00 (end)\n", i);
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/* Install our function as the int13h handler in the IVT. */
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*int13slot = ((grub_uint32_t) handler_base) << 12; /* Segment address. */
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grub_dprintf ("drivemap", "New int13 handler: %04x:%04x\n",
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(*int13slot >> 16) & 0x0ffff, *int13slot & 0x0ffff);
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return GRUB_ERR_NONE;
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}
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static grub_err_t
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uninstall_int13_handler (void)
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{
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if (! grub_drivemap_oldhandler)
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return GRUB_ERR_NONE;
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*int13slot = grub_drivemap_oldhandler;
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grub_mmap_free_and_unregister (drivemap_mmap);
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grub_drivemap_oldhandler = 0;
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grub_dprintf ("drivemap", "Restored int13 handler: %04x:%04x\n",
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(*int13slot >> 16) & 0x0ffff, *int13slot & 0x0ffff);
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return GRUB_ERR_NONE;
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}
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static int
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grub_get_root_biosnumber_drivemap (void)
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{
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const char *biosnum;
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int ret = -1;
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grub_device_t dev;
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biosnum = grub_env_get ("biosnum");
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if (biosnum)
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return grub_strtoul (biosnum, 0, 0);
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dev = grub_device_open (0);
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if (dev && dev->disk && dev->disk->dev
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&& dev->disk->dev->id == GRUB_DISK_DEVICE_BIOSDISK_ID)
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{
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drivemap_node_t *curnode = map_head;
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ret = (int) dev->disk->id;
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while (curnode)
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{
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if (curnode->redirto == ret)
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{
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ret = curnode->newdrive;
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break;
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}
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curnode = curnode->next;
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}
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}
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if (dev)
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grub_device_close (dev);
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return ret;
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}
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static grub_extcmd_t cmd;
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static int (*grub_get_root_biosnumber_saved) (void);
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GRUB_MOD_INIT (drivemap)
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{
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grub_get_root_biosnumber_saved = grub_get_root_biosnumber;
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grub_get_root_biosnumber = grub_get_root_biosnumber_drivemap;
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cmd = grub_register_extcmd ("drivemap", grub_cmd_drivemap, 0,
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N_("-l | -r | [-s] grubdev osdisk."),
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N_("Manage the BIOS drive mappings."),
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options);
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drivemap_hook =
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grub_loader_register_preboot_hook (&install_int13_handler,
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&uninstall_int13_handler,
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GRUB_LOADER_PREBOOT_HOOK_PRIO_NORMAL);
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}
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GRUB_MOD_FINI (drivemap)
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{
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grub_get_root_biosnumber = grub_get_root_biosnumber_saved;
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grub_loader_unregister_preboot_hook (drivemap_hook);
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drivemap_hook = 0;
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grub_unregister_extcmd (cmd);
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}
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