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https://codeberg.org/libreboot/lbmk.git
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f2544d094b
part of the same code library as nvmutil. as part of this, i renamed util/nvmutil to util/libreboot-utils/ because it is now a multi-utility codebase. this is more efficient, since i also wish to use mkhtemp (function) in nvmutil. Signed-off-by: Leah Rowe <leah@libreboot.org>
109 lines
1.9 KiB
C
109 lines
1.9 KiB
C
/* SPDX-License-Identifier: MIT
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* Copyright (c) 2022-2026 Leah Rowe <leah@libreboot.org>
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*
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* Functions related to GbE NVM checksums.
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*/
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <errno.h>
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#include <limits.h>
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#include <stddef.h>
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#include <stdlib.h>
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#include "../include/common.h"
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void
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read_checksums(void)
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{
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struct xstate *x = xstatus();
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struct commands *cmd = &x->cmd[x->i];
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struct xfile *f = &x->f;
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size_t _p;
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size_t _skip_part;
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unsigned char _num_invalid;
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unsigned char _max_invalid;
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f->part_valid[0] = 0;
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f->part_valid[1] = 0;
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if (!cmd->chksum_read)
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return;
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_num_invalid = 0;
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_max_invalid = 2;
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if (cmd->arg_part)
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_max_invalid = 1;
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/* Skip verification on this part,
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* but only when arg_part is set.
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*/
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_skip_part = f->part ^ 1;
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for (_p = 0; _p < 2; _p++) {
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/* Only verify a part if it was *read*
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*/
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if (cmd->arg_part && (_p == _skip_part))
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continue;
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f->part_valid[_p] = good_checksum(_p);
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if (!f->part_valid[_p])
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++_num_invalid;
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}
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if (_num_invalid >= _max_invalid) {
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if (_max_invalid == 1)
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err(ECANCELED, "%s: part %lu has a bad checksum",
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f->fname, (size_t)f->part);
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err(ECANCELED, "%s: No valid checksum found in file",
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f->fname);
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}
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}
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int
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good_checksum(size_t partnum)
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{
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unsigned short expected_checksum;
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unsigned short actual_checksum;
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expected_checksum =
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calculated_checksum(partnum);
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actual_checksum =
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nvm_word(NVM_CHECKSUM_WORD, partnum);
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if (expected_checksum == actual_checksum) {
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return 1;
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} else {
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return 0;
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}
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}
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void
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set_checksum(size_t p)
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{
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check_bin(p, "part number");
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set_nvm_word(NVM_CHECKSUM_WORD, p, calculated_checksum(p));
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}
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unsigned short
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calculated_checksum(size_t p)
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{
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size_t c;
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unsigned int val16;
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val16 = 0;
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for (c = 0; c < NVM_CHECKSUM_WORD; c++)
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val16 += (unsigned int)nvm_word(c, p);
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return (unsigned short)((NVM_CHECKSUM - val16) & 0xffff);
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}
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