mirror of
https://github.com/jart/cosmopolitan.git
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replace strings in ELF .rodata sections
This commit is contained in:
Gautham
parent
102edf4ea2
commit
3a67dd0b31
1 changed files with 489 additions and 0 deletions
489
tool/build/renamestr.c
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489
tool/build/renamestr.c
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@ -0,0 +1,489 @@
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/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
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│ vi: set et ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi │
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╞══════════════════════════════════════════════════════════════════════════════╡
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│ Copyright 2024 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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#include "libc/calls/calls.h"
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#include "libc/elf/def.h"
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#include "libc/elf/elf.h"
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#include "libc/elf/scalar.h"
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#include "libc/elf/struct/ehdr.h"
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#include "libc/elf/struct/phdr.h"
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#include "libc/intrin/kprintf.h"
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#include "libc/macros.h"
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#include "libc/mem/mem.h"
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#include "libc/runtime/runtime.h"
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#include "libc/runtime/symbols.internal.h"
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#include "libc/stdio/stdio.h"
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#include "libc/str/str.h"
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#include "libc/sysv/consts/map.h"
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#include "libc/sysv/consts/o.h"
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#include "libc/sysv/consts/prot.h"
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#include "third_party/getopt/getopt.internal.h"
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#define VERSION \
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"renamestr v0.1\n" \
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"https://github.com/jart/cosmopolitan\n"
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#define MANUAL \
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" -f FROM -t TO -o OUTPUT INPUT \n" \
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"\n" \
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"DESCRIPTION\n" \
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"\n" \
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" string replacement in ELF binary .rodata\n" \
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"\n" \
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" this program may be used to replace strings in the\n" \
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" .rodata sections of ELF binaries.\n" \
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"\n" \
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"FLAGS\n" \
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"\n" \
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" -h show usage\n" \
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"\n" \
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" -v show version\n" \
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"\n" \
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" -f FROM source string to replace\n" \
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"\n" \
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" -t TO target string replacement. must be shorter\n" \
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" than FROM string for replacement to work\n" \
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"\n" \
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" -o OUTPUT output file\n" \
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"\n" \
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" INPUT ELF binary containing strings to replace\n" \
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"\n"
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static const char *prog;
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static const char *exepath;
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static Elf64_Shdr *rodata;
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static char *rostart;
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static char *roend;
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static const char *outpath;
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static int outfd;
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static wontreturn void Die(const char *thing, const char *reason) {
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tinyprint(2, thing, ": ", reason, "\n", NULL);
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exit(1);
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}
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static wontreturn void DieSys(const char *thing) {
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perror(thing);
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exit(1);
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}
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static wontreturn void ShowUsage(int rc, int fd) {
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tinyprint(fd, "USAGE\n\n ", prog, MANUAL, NULL);
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exit(rc);
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}
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static wontreturn void DieOom(void) {
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Die("renamestr", "out of memory");
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}
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static void *Malloc(size_t n) {
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void *p;
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if (!(p = malloc(n)))
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DieOom();
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return p;
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}
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static void *Realloc(void *p, size_t n) {
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if (!(p = realloc(p, n)))
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DieOom();
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return p;
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}
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static void Pwrite(const void *data, size_t size, uint64_t offset) {
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ssize_t rc;
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const char *p, *e;
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for (p = data, e = p + size; p < e; p += (size_t)rc, offset += (size_t)rc) {
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if ((rc = pwrite(outfd, p, e - p, offset)) == -1) {
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DieSys(outpath);
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}
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}
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}
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struct Param {
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const char *from_string;
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size_t from_len;
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const char *to_string;
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size_t to_len;
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int count;
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char *roloc;
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};
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struct Params {
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int n;
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struct Param p[4];
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};
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static struct Params params;
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static void GetOpts(int argc, char *argv[]) {
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int opt;
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bool partial = false;
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params.n = 0;
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struct Param *param;
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while ((opt = getopt(argc, argv, "hvf:t:o:")) != -1) {
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if (params.n >= ARRAYLEN(params.p)) {
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param = NULL;
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} else {
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param = &(params.p[params.n]);
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}
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switch (opt) {
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case 'o':
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if (outpath) {
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Die(prog, "outpath already provided");
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}
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outpath = optarg;
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break;
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case 'f':
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if (!param) {
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Die(prog, "too many replacements provided");
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}
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if (param->from_string) {
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Die(prog, "from string already provided");
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}
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param->from_string = optarg;
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param->from_len = strlen(optarg);
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partial = !partial;
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break;
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case 't':
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if (!param) {
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Die(prog, "too many replacements provided");
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}
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if (param->to_string) {
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Die(prog, "to string already provided");
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}
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param->to_string = optarg;
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param->to_len = strlen(optarg);
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partial = !partial;
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break;
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case 'v':
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tinyprint(0, VERSION, NULL);
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exit(0);
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case 'h':
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ShowUsage(0, 1);
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default:
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ShowUsage(1, 2);
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}
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if (param->from_string && param->to_string) {
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if (param->from_len < param->to_len) {
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Die(prog, "to_string longer than from_string, cannot replace");
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}
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params.n++;
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}
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}
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if (params.n == 0) {
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Die(prog, "no replacements provided");
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}
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if (partial) {
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Die(prog, "partial replacement provided");
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}
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for (int i = 0; i < params.n; ++i) { // no-op
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if (!params.p[i].from_string) {
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Die(prog, "need from_string for replacement");
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}
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if (!params.p[i].to_string) {
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Die(prog, "need to_string for replacement");
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}
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}
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if (!outpath) {
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Die(prog, "need outpath to write file");
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}
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if (optind == argc) {
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Die(prog, "missing input argument");
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}
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if (optind != argc - 1) {
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Die(prog, "too many args");
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}
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exepath = argv[optind];
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}
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static void ValidateElfImage(Elf64_Ehdr *e, Elf64_Off esize, //
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const char *epath) {
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// validate elf header
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if (e->e_type != ET_EXEC && e->e_type != ET_DYN)
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Die(epath, "elf binary isn't an executable");
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if (!e->e_phnum)
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Die(epath, "elf executable needs at least one program header");
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if (e->e_phnum > 65534)
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Die(epath, "elf with more than 65534 phdrs not supported");
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if (e->e_phentsize != sizeof(Elf64_Phdr))
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Die(epath, "elf e_phentsize isn't sizeof(Elf64_Phdr)");
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if (e->e_phoff > esize)
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Die(epath, "elf program header offset points past image eof");
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if (e->e_phoff & 7)
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Die(epath, "elf e_phoff must be aligned on an 8-byte boundary");
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if (e->e_phoff + e->e_phoff + e->e_phnum * sizeof(Elf64_Phdr) > esize)
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Die(epath, "elf program header array overlaps image eof");
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// determine microprocessor page size requirement
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//
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// even though operating systems (windows) and c libraries (cosmo)
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// sometimes impose a larger page size requirement than the actual
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// microprocessor itself, the cpu page size is still the only page
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// size that actually matters when it comes to executable loading.
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unsigned long pagesz;
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if (e->e_machine == EM_AARCH64) {
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pagesz = 16384; // apple m1 (xnu, linux)
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} else { //
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pagesz = 4096; // x86-64, raspberry pi
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}
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// remove empty segment loads
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// empty loads should be inconsequential; linux ignores them
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// however they tend to trip up many systems such as openbsd
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int i, j;
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Elf64_Phdr *p = (Elf64_Phdr *)((char *)e + e->e_phoff);
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for (i = 0; i < e->e_phnum;) {
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if (p[i].p_type == PT_LOAD && !p[i].p_memsz) {
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if (i + 1 < e->e_phnum) {
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memmove(p + i, p + i + 1, (e->e_phnum - (i + 1)) * sizeof(*p));
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}
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--e->e_phnum;
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} else {
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++i;
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}
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}
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// oracle says loadable segment entries in the program header table
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// appear in ascending order, sorted on the p_vaddr member.
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int found_load = 0;
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Elf64_Addr last_vaddr = 0;
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for (i = 0; i < e->e_phnum; ++i) {
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if (p[i].p_type != PT_LOAD)
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continue;
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if (found_load && p[i].p_vaddr <= last_vaddr) {
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Die(epath, "ELF PT_LOAD segments must be ordered by p_vaddr");
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}
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last_vaddr = p[i].p_vaddr;
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found_load = 1;
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}
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if (!found_load) {
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Die(epath, "ELF must have at least one PT_LOAD segment");
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}
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// merge adjacent loads that are contiguous with equal protection
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for (i = 0; i + 1 < e->e_phnum;) {
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if (p[i].p_type == PT_LOAD && p[i + 1].p_type == PT_LOAD &&
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((p[i].p_flags & (PF_R | PF_W | PF_X)) ==
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(p[i + 1].p_flags & (PF_R | PF_W | PF_X))) &&
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((p[i].p_offset + p[i].p_filesz + (pagesz - 1)) & -pagesz) -
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(p[i + 1].p_offset & -pagesz) <=
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pagesz &&
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((p[i].p_vaddr + p[i].p_memsz + (pagesz - 1)) & -pagesz) -
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(p[i + 1].p_vaddr & -pagesz) <=
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pagesz) {
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p[i].p_memsz = (p[i + 1].p_vaddr + p[i + 1].p_memsz) - p[i].p_vaddr;
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p[i].p_filesz = (p[i + 1].p_offset + p[i + 1].p_filesz) - p[i].p_offset;
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if (i + 2 < e->e_phnum) {
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memmove(p + i + 1, p + i + 2, (e->e_phnum - (i + 2)) * sizeof(*p));
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}
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--e->e_phnum;
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} else {
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++i;
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}
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}
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// validate program headers
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bool found_entry = false;
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for (i = 0; i < e->e_phnum; ++i) {
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if (p[i].p_type == PT_INTERP) {
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Die(epath, "ELF has PT_INTERP which isn't supported");
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}
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if (p[i].p_type == PT_DYNAMIC) {
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Die(epath, "ELF has PT_DYNAMIC which isn't supported");
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}
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if (p[i].p_type != PT_LOAD) {
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continue;
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}
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if (!p[i].p_memsz) {
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Die(epath, "ELF PT_LOAD p_memsz was zero");
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}
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if (p[i].p_offset > esize) {
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Die(epath, "ELF PT_LOAD p_offset points past EOF");
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}
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if (p[i].p_filesz > p[i].p_memsz) {
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Die(epath, "ELF PT_LOAD p_filesz exceeds p_memsz");
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}
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if (p[i].p_align > 1 && (p[i].p_align & (p[i].p_align - 1))) {
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Die(epath, "ELF PT_LOAD p_align must be two power");
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}
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if (p[i].p_vaddr + p[i].p_memsz < p[i].p_vaddr ||
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p[i].p_vaddr + p[i].p_memsz + (pagesz - 1) < p[i].p_vaddr) {
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Die(epath, "ELF PT_LOAD p_vaddr + p_memsz overflow");
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}
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if (p[i].p_offset + p[i].p_filesz < p[i].p_offset ||
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p[i].p_offset + p[i].p_filesz + (pagesz - 1) < p[i].p_offset) {
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Die(epath, "ELF PT_LOAD p_offset + p_filesz overflow");
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}
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if (p[i].p_align > 1 && ((p[i].p_vaddr & (p[i].p_align - 1)) !=
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(p[i].p_offset & (p[i].p_align - 1)))) {
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Die(epath, "ELF p_vaddr incongruent w/ p_offset modulo p_align");
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}
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if ((p[i].p_vaddr & (pagesz - 1)) != (p[i].p_offset & (pagesz - 1))) {
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Die(epath, "ELF p_vaddr incongruent w/ p_offset modulo AT_PAGESZ");
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}
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if (p[i].p_offset + p[i].p_filesz > esize) {
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Die(epath, "ELF PT_LOAD p_offset and p_filesz overlaps image EOF");
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}
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Elf64_Off a = p[i].p_vaddr & -pagesz;
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Elf64_Off b = (p[i].p_vaddr + p[i].p_memsz + (pagesz - 1)) & -pagesz;
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for (j = i + 1; j < e->e_phnum; ++j) {
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if (p[j].p_type != PT_LOAD)
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continue;
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Elf64_Off c = p[j].p_vaddr & -pagesz;
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Elf64_Off d = (p[j].p_vaddr + p[j].p_memsz + (pagesz - 1)) & -pagesz;
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if (MAX(a, c) < MIN(b, d)) {
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Die(epath,
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"ELF PT_LOAD phdrs %d and %d overlap each others virtual memory");
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}
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}
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if (e->e_machine == EM_AARCH64 &&
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p[i].p_vaddr + p[i].p_memsz > 0x0001000000000000) {
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Die(epath, "this is an ARM ELF program but it loads to virtual"
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" memory addresses outside the legal range [0,2^48)");
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}
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if (e->e_machine == EM_NEXGEN32E &&
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!(-140737488355328 <= (Elf64_Sxword)p[i].p_vaddr &&
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(Elf64_Sxword)(p[i].p_vaddr + p[i].p_memsz) <= 140737488355328)) {
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Die(epath, "this is an x86-64 ELF program, but it loads to virtual"
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" memory addresses outside the legal range [-2^47,2^47)");
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}
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if ((p[i].p_flags & PF_X) && //
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p[i].p_vaddr <= e->e_entry &&
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e->e_entry < p[i].p_vaddr + p[i].p_memsz) {
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found_entry = 1;
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}
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}
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if (!found_entry) {
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Die(epath, "ELF entrypoint not found in PT_LOAD with PF_X");
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}
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}
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struct Input {
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union {
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char *map;
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Elf64_Ehdr *elf;
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unsigned char *umap;
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};
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size_t size;
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const char *path;
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};
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static struct Input input;
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static void OpenInput(const char *path) {
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int fd;
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if ((fd = open(path, O_RDONLY)) == -1)
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DieSys(path);
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if ((input.size = lseek(fd, 0, SEEK_END)) == -1)
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DieSys(path);
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input.path = path;
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input.map = mmap(0, input.size, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0);
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if (input.map == MAP_FAILED)
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DieSys(path);
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if (!IsElf64Binary(input.elf, input.size))
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Die(path, "not an elf64 binary");
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close(fd);
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}
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static void ReplaceString(struct Param *param) {
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Elf64_Xword len = strnlen(param->roloc, roend - param->roloc);
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char *targstr = Malloc(len);
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for (Elf64_Xword i = 0; i < len; ++i)
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targstr[i] = 0;
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strcat(targstr, param->to_string);
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strcat(targstr, param->roloc + param->from_len);
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#ifdef MODE_DBG
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kprintf("'%s' should be '%s'\n", param->roloc, targstr);
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#endif
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strcpy(param->roloc, targstr);
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param->roloc += len;
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}
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int main(int argc, char *argv[]) {
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#ifdef MODE_DBG
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ShowCrashReports();
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||||
#endif
|
||||
|
||||
prog = argv[0];
|
||||
|
||||
if (!prog)
|
||||
prog = "renamestr";
|
||||
|
||||
GetOpts(argc, argv);
|
||||
OpenInput(exepath);
|
||||
ValidateElfImage(input.elf, input.size, input.path);
|
||||
rodata = FindElfSectionByName(
|
||||
input.elf, input.size,
|
||||
GetElfSectionNameStringTable(input.elf, input.size), ".rodata");
|
||||
if (!rodata)
|
||||
Die(exepath, "doesn't have .rodata");
|
||||
|
||||
rostart = GetElfSectionAddress(input.elf, input.size, rodata);
|
||||
if (!rostart)
|
||||
Die(prog, "could not get to start of .rodata");
|
||||
roend = rostart + rodata->sh_size;
|
||||
|
||||
#ifdef MODE_DBG
|
||||
kprintf("elf file to process: %s\n", exepath);
|
||||
kprintf("file size is %ld\n", input.size);
|
||||
#endif
|
||||
for (int i = 0; i < params.n; ++i) {
|
||||
struct Param *param = &(params.p[i]);
|
||||
param->roloc = rostart;
|
||||
param->count = 0;
|
||||
#ifdef MODE_DBG
|
||||
kprintf("need to replace '%s' with '%s'\n", param->from_string,
|
||||
param->to_string);
|
||||
#endif
|
||||
}
|
||||
|
||||
#define NEXT_ROLOC(z) \
|
||||
memmem((z)->roloc, roend - (z)->roloc, (z)->from_string, (z)->from_len)
|
||||
for (int i = 0; i < params.n; ++i) {
|
||||
struct Param *param = &(params.p[i]);
|
||||
for (param->roloc = NEXT_ROLOC(param); param->roloc != NULL;
|
||||
param->roloc = NEXT_ROLOC(param)) {
|
||||
if (param->roloc == rostart ||
|
||||
param->roloc[-1] == '\0') { // confirm start of string
|
||||
ReplaceString(param);
|
||||
param->count++;
|
||||
} else {
|
||||
// in the middle of a string, so move forward
|
||||
param->roloc += param->from_len;
|
||||
}
|
||||
}
|
||||
}
|
||||
#undef NEXT_ROLOC
|
||||
|
||||
if ((outfd = creat(outpath, 0755)) == -1) {
|
||||
Die(prog, "unable to open file for writing");
|
||||
}
|
||||
Pwrite(input.map, input.size, 0);
|
||||
if (close(outfd)) {
|
||||
Die(prog, "unable to close file after writing");
|
||||
}
|
||||
|
||||
for (int i = 0; i < params.n; ++i) {
|
||||
struct Param *param = &(params.p[i]);
|
||||
printf("'%s' -> '%s': %d replacements\n", param->from_string,
|
||||
param->to_string, param->count);
|
||||
}
|
||||
return 0;
|
||||
}
|
||||
Loading…
Add table
Add a link
Reference in a new issue