132 lines
3.6 KiB
C
132 lines
3.6 KiB
C
// crossfire: distributed brute force infrastructure
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//
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// Copyright (C) 2020 haskal
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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 Affero General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU Affero General Public License for more details.
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//
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// You should have received a copy of the GNU Affero General Public License
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// along with this program. If not, see <https://www.gnu.org/licenses/>.
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#pragma once
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#include <sys/types.h>
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#include <elf.h>
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#include <fcntl.h>
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#include <string.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include <stdint.h>
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#include <stdbool.h>
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#include <sys/mman.h>
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#include <errno.h>
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#define _SELF_NAME "/proc/self/exe"
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#if ELF_BITS == 32
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#define Elf_Ehdr Elf32_Ehdr
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#define Elf_Shdr Elf32_Shdr
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#elif ELF_BITS == 64
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#define Elf_Ehdr Elf64_Ehdr
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#define Elf_Shdr Elf64_Shdr
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#endif
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#define CHK_GENERIC(what, ret) if (what) { return ret; }
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#define CHK_NULL_NULL(what) CHK_GENERIC(what == NULL, NULL)
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#define CHK_NEG_NEG(what) CHK_GENERIC(what < 0, -1)
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static inline char* readlink_exactly(const char* name) {
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ssize_t len;
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ssize_t blen = 256;
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char* s = malloc(blen);
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CHK_NULL_NULL(s);
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while (true) {
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len = readlink(name, s, blen - 1);
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if (len == (blen - 1)) {
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free(s);
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blen *= 2;
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s = malloc(blen);
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CHK_NULL_NULL(s);
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} else if (len < 0) {
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return NULL;
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} else {
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return s;
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}
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}
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}
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static inline int readexactly(int fd, uint8_t* buf, size_t size) {
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for (size_t i = 0; i < size;) {
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ssize_t res = read(fd, &buf[i], size - i);
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if (res < 0) {
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if (errno == EINTR) { continue; }
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return -1;
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}
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i += res;
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}
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return size;
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}
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typedef struct {
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char* self_name;
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size_t self_size;
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void* self_mm;
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Elf_Ehdr* ehdr;
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char* strs;
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} boot_ctx;
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typedef struct {
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off_t offset;
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size_t size;
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} boot_lookup;
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static int init_boot_ctx(boot_ctx* ctx) {
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// i fucking hate C
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char* self_name = readlink_exactly(_SELF_NAME);
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CHK_GENERIC(self_name == NULL, -1);
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ctx->self_name = self_name;
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int fd = open(self_name, O_RDONLY);
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CHK_NEG_NEG(fd);
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ssize_t len = lseek(fd, 0, SEEK_END);
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CHK_NEG_NEG(len);
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ctx->self_size = len;
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void* map = mmap(NULL, len, PROT_READ, MAP_SHARED, fd, 0);
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CHK_GENERIC(map == MAP_FAILED, -1);
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CHK_NEG_NEG(close(fd));
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ctx->self_mm = map;
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ctx->ehdr = map;
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off_t shdr_off = ctx->ehdr->e_shoff + (ctx->ehdr->e_shstrndx * ctx->ehdr->e_shentsize);
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Elf_Shdr* shdr = (void*) (((uint8_t*) map) + shdr_off);
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ctx->strs = ((uint8_t*) map) + shdr->sh_offset;
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return 0;
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}
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static boot_lookup boot_ctx_lookup(boot_ctx* ctx, const char* sectname) {
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boot_lookup bl = { (off_t) -1, (size_t) -1 };
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for (size_t i = 0; i < ctx->ehdr->e_shnum; i++) {
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Elf_Shdr* shdr = (void*) (((uint8_t*) ctx->self_mm)
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+ ctx->ehdr->e_shoff + (i * ctx->ehdr->e_shentsize));
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if (!strcmp(ctx->strs + shdr->sh_name, sectname)) {
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bl.offset = shdr->sh_offset;
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bl.size = shdr->sh_size;
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return bl;
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}
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}
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return bl;
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}
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static void unload_boot_ctx(boot_ctx* ctx) {
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free(ctx->self_name);
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if (munmap(ctx->self_mm, ctx->self_size) < 0) {
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printf("NO SHONKS\n");
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exit(-1);
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}
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}
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