71 lines
6.7 KiB
C
71 lines
6.7 KiB
C
/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
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│vi: set net ft=c ts=8 sts=2 sw=2 fenc=utf-8 :vi│
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╞══════════════════════════════════════════════════════════════════════════════╡
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│ Copyright 2020 Justine Alexandra Roberts Tunney │
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│ │
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│ This program 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; version 2 of the License. │
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│ │
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│ This program is distributed in the hope that it will be useful, but │
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│ WITHOUT ANY WARRANTY; without even the implied warranty of │
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│ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU │
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│ 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 this program; if not, write to the Free Software │
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│ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA │
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│ 02110-1301 USA │
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╠──────────────────────────────────────────────────────────────────────────────╣
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│░░░░░░░▀▀▀░▀░▀░▀▀▀░▀▀▀░▀▀▀░░▀░░▀░▀░▀▀▀░▀▀░▀▀▀░░░░░░░░░░▄██▀█▌░██▄▄░░▐█▀▄░▐█▀░░│
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│░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░▐█▀▀▌░░░▄▀▌░▌░█░▌░░▌░▌░░│
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╠──────────────────────────────────────────────────────▌▀▄─▐──▀▄─▐▄─▐▄▐▄─▐▄─▐▄─│
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│ αcτµαlly pδrταblε εxεcµταblε § post-initialization read-only │
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╚─────────────────────────────────────────────────────────────────────────────*/
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#include "libc/bits/safemacros.internal.h"
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#include "libc/bits/weaken.h"
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#include "libc/calls/calls.h"
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#include "libc/runtime/internal.h"
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#include "libc/runtime/runtime.h"
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#include "libc/sysv/consts/prot.h"
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#define getaddr(section) ((intptr_t)weakaddr(section))
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static textstartup void _piro_protect(intptr_t start, intptr_t end, int prot) {
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ssize_t len = end - start;
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if (len > 0 && start && start % PAGESIZE == 0 && len % PAGESIZE == 0) {
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if (mprotect((void *)(unsigned long)start, len, prot) == -1) abort();
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}
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}
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/**
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* Protects memory initialized at startup.
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* e.g. function hooks, unpacked data structures, etc.
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*
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* This is only performed for executables of nontrivial size. It won't
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* break the build if the αpε linker script wasn't used. Test code is
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* protected too, so we don't end up like Knight Capital.
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*
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* @param prot can have PROT_{NONE,READ,WRITE,EXEC}
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* @see ape/ape.lds
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* @see libc/_start.S
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*/
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textstartup void _piro(int prot) {
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if (getaddr("main") < getaddr("__test_start")) {
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_piro_protect(getaddr("__test_start"), getaddr("__test_end"), PROT_NONE);
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}
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_piro_protect(getaddr("__ro"), getaddr("_etext"), PROT_READ);
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_piro_protect(getaddr("__piro_start"), getaddr("__piro_end"), prot);
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}
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