1 /* ----------------------------------------------------------------------- * 2 * 3 * Copyright 1998-2008 H. Peter Anvin - All Rights Reserved 4 * Copyright 2009-2014 Intel Corporation; author H. Peter Anvin 5 * 6 * This program is free software; you can redistribute it and/or modify 7 * it under the terms of the GNU General Public License as published by 8 * the Free Software Foundation, Inc., 53 Temple Place Ste 330, 9 * Boston MA 02111-1307, USA; either version 2 of the License, or 10 * (at your option) any later version; incorporated herein by reference. 11 * 12 * ----------------------------------------------------------------------- */ 13 14 /* 15 * syslxmod.c - Code to provide a SYSLINUX code set to an installer. 16 */ 17 18 #define _XOPEN_SOURCE 500 /* Required on glibc 2.x */ 19 #define _BSD_SOURCE 20 /* glibc 2.20 deprecates _BSD_SOURCE in favour of _DEFAULT_SOURCE */ 21 #define _DEFAULT_SOURCE 1 22 #include <stdio.h> 23 #include <inttypes.h> 24 #include <string.h> 25 #include <stddef.h> 26 #include <stdlib.h> 27 28 #include "syslinux.h" 29 #include "syslxint.h" 30 31 32 /* 33 * Generate sector extents 34 */ 35 static void generate_extents(struct syslinux_extent _slimg *ex, int nptrs, 36 const sector_t *sectp, int nsect) 37 { 38 uint32_t addr = 0x8000; /* ldlinux.sys starts loading here */ 39 uint32_t base; 40 sector_t sect, lba; 41 unsigned int len; 42 43 base = addr; 44 len = lba = 0; 45 46 memset_sl(ex, 0, nptrs * sizeof *ex); 47 48 while (nsect) { 49 sect = *sectp++; 50 51 if (len) { 52 uint32_t xbytes = (len + 1) * SECTOR_SIZE; 53 54 if (sect == lba + len && xbytes < 65536 && 55 ((addr ^ (base + xbytes - 1)) & 0xffff0000) == 0) { 56 /* We can add to the current extent */ 57 len++; 58 goto next; 59 } 60 61 set_64_sl(&ex->lba, lba); 62 set_16_sl(&ex->len, len); 63 ex++; 64 } 65 66 base = addr; 67 lba = sect; 68 len = 1; 69 70 next: 71 addr += SECTOR_SIZE; 72 nsect--; 73 } 74 75 if (len) { 76 set_64_sl(&ex->lba, lba); 77 set_16_sl(&ex->len, len); 78 ex++; 79 } 80 } 81 82 /* 83 * Form a pointer based on a 16-bit patcharea/epa field 84 */ 85 static inline void *ptr(void *img, const uint16_t _slimg *offset_p) 86 { 87 return (char *)img + get_16_sl(offset_p); 88 } 89 static inline void _slimg *slptr(void _slimg *img, 90 const uint16_t _slimg *offset_p) 91 { 92 return (char _slimg *)img + get_16_sl(offset_p); 93 } 94 95 /* 96 * This patches the boot sector and the beginning of ldlinux.sys 97 * based on an ldlinux.sys sector map passed in. Typically this is 98 * handled by writing ldlinux.sys, mapping it, and then overwrite it 99 * with the patched version. If this isn't safe to do because of 100 * an OS which does block reallocation, then overwrite it with 101 * direct access since the location is known. 102 * 103 * Returns the number of modified bytes in ldlinux.sys if successful, 104 * otherwise -1. 105 */ 106 int syslinux_patch(const sector_t *sectp, int nsectors, 107 int stupid, int raid_mode, 108 const char *subdir, const char *subvol) 109 { 110 struct patch_area _slimg *patcharea; 111 struct ext_patch_area _slimg *epa; 112 struct syslinux_extent _slimg *ex; 113 const uint32_t _slimg *wp; 114 int nsect = ((boot_image_len + SECTOR_SIZE - 1) >> SECTOR_SHIFT) + 2; 115 uint32_t csum; 116 int i, dw, nptrs; 117 struct fat_boot_sector *sbs = (struct fat_boot_sector *)boot_sector; 118 uint64_t _slimg *advptrs; 119 120 if (nsectors < nsect) 121 return -1; /* The actual file is too small for content */ 122 123 /* Search for LDLINUX_MAGIC to find the patch area */ 124 for (wp = (const uint32_t _slimg *)boot_image; 125 get_32_sl(wp) != LDLINUX_MAGIC; 126 wp++) 127 ; 128 patcharea = (struct patch_area _slimg *)wp; 129 epa = slptr(boot_image, &patcharea->epaoffset); 130 131 /* First sector need pointer in boot sector */ 132 set_32(ptr(sbs, &epa->sect1ptr0), sectp[0]); 133 set_32(ptr(sbs, &epa->sect1ptr1), sectp[0] >> 32); 134 sectp++; 135 136 /* Handle RAID mode */ 137 if (raid_mode) { 138 /* Patch in INT 18h = CD 18 */ 139 set_16(ptr(sbs, &epa->raidpatch), 0x18CD); 140 } 141 142 /* Set up the totals */ 143 dw = boot_image_len >> 2; /* COMPLETE dwords, excluding ADV */ 144 set_16_sl(&patcharea->data_sectors, nsect - 2); /* Not including ADVs */ 145 set_16_sl(&patcharea->adv_sectors, 2); /* ADVs need 2 sectors */ 146 set_32_sl(&patcharea->dwords, dw); 147 148 /* Handle Stupid mode */ 149 if (stupid) { 150 /* Access only one sector at a time */ 151 set_16_sl(&patcharea->maxtransfer, 1); 152 } 153 154 /* Set the sector extents */ 155 ex = slptr(boot_image, &epa->secptroffset); 156 nptrs = get_16_sl(&epa->secptrcnt); 157 158 #if 0 159 if (nsect > nptrs) { 160 /* Not necessarily an error in this case, but a general problem */ 161 fprintf(stderr, "Insufficient extent space, build error!\n"); 162 exit(1); 163 } 164 #endif 165 166 /* -1 for the pointer in the boot sector, -2 for the two ADVs */ 167 generate_extents(ex, nptrs, sectp, nsect-1-2); 168 169 /* ADV pointers */ 170 advptrs = slptr(boot_image, &epa->advptroffset); 171 set_64_sl(&advptrs[0], sectp[nsect-1-2]); 172 set_64_sl(&advptrs[1], sectp[nsect-1-1]); 173 174 /* Poke in the base directory path */ 175 if (subdir) { 176 int sublen = strlen(subdir) + 1; 177 if (get_16_sl(&epa->dirlen) < sublen) { 178 fprintf(stderr, "Subdirectory path too long... aborting install!\n"); 179 exit(1); 180 } 181 memcpy_to_sl(slptr(boot_image, &epa->diroffset), subdir, sublen); 182 } 183 184 /* Poke in the subvolume information */ 185 if (subvol) { 186 int sublen = strlen(subvol) + 1; 187 if (get_16_sl(&epa->subvollen) < sublen) { 188 fprintf(stderr, "Subvol name too long... aborting install!\n"); 189 exit(1); 190 } 191 memcpy_to_sl(slptr(boot_image, &epa->subvoloffset), subvol, sublen); 192 } 193 194 /* Now produce a checksum */ 195 set_32_sl(&patcharea->checksum, 0); 196 197 csum = LDLINUX_MAGIC; 198 for (i = 0, wp = (const uint32_t _slimg *)boot_image; i < dw; i++, wp++) 199 csum -= get_32_sl(wp); /* Negative checksum */ 200 201 set_32_sl(&patcharea->checksum, csum); 202 203 /* 204 * Assume all bytes modified. This can be optimized at the expense 205 * of keeping track of what the highest modified address ever was. 206 */ 207 return dw << 2; 208 } 209
