70 lines
6.6 KiB
C
70 lines
6.6 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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│ Permission to use, copy, modify, and/or distribute this software for │
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│ any purpose with or without fee is hereby granted, provided that the │
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│ above copyright notice and this permission notice appear in all copies. │
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│ │
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│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
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│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
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│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
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│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
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│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
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│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
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│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
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│ PERFORMANCE OF THIS SOFTWARE. │
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╠──────────────────────────────────────────────────────────────────────────────╣
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│░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░│
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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.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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