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/* $OpenBSD: prebind_delete.c,v 1.4 2006/05/13 16:33:40 deraadt Exp $ */
/*
* Copyright (c) 2006 Dale Rahn <drahn@dalerahn.com>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#include <sys/types.h>
#include <sys/mman.h>
#include <sys/exec_elf.h>
#include <elf_abi.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include <errno.h>
#include "prebind.h"
#define BUFSZ (256 * 1024)
int strip_prebind(char *file);
int prebind_remove_load_section(int fd, char *name);
int prebind_newfile(int fd, char *name, struct stat *st,
struct prebind_footer *footer);
extern int verbose;
int
prebind_delete(char **argv)
{
while (*argv) {
if (strip_prebind(*argv) == -1)
return (1);
argv++;
}
return (0);
}
int
strip_prebind(char *file)
{
struct prebind_footer footer;
extern char *__progname;
int fd, rdonly = 0;
struct stat st;
ssize_t bytes;
fd = open(file, O_RDWR);
if (fd == -1 && errno == ETXTBSY) {
fd = open(file, O_RDONLY);
rdonly = 1;
}
if (fd == -1) {
warn("%s", file);
return (-1);
}
if (fstat(fd, &st) == -1)
return (-1);
lseek(fd, -((off_t)sizeof(struct prebind_footer)), SEEK_END);
bytes = read(fd, &footer, sizeof(struct prebind_footer));
if (bytes != sizeof(struct prebind_footer))
goto done;
if (footer.bind_id[0] != BIND_ID0 || footer.bind_id[1] != BIND_ID1 ||
footer.bind_id[2] != BIND_ID2 || footer.bind_id[3] != BIND_ID3) {
if (verbose)
fprintf(stderr, "%s: no prebind header\n", file);
goto done;
}
if (rdonly) {
fd = prebind_newfile(fd, file, &st, &footer);
} else {
prebind_remove_load_section(fd, file);
ftruncate(fd, footer.orig_size);
}
if (verbose)
fprintf(stderr, "%s: stripped %lld bytes from %s\n",
__progname, st.st_size - footer.orig_size, file);
done:
if (fd != -1)
close(fd);
return (0);
}
int
prebind_remove_load_section(int fd, char *name)
{
Elf_Ehdr *ehdr;
Elf_Phdr *phdr;
int loadsection;
char *buf;
buf = mmap(NULL, 8192, PROT_READ|PROT_WRITE, MAP_FILE | MAP_SHARED,
fd, 0);
if (buf == MAP_FAILED) {
if (verbose)
warn("%s: cannot mmap for for write", name);
return (-1);
}
ehdr = (Elf_Ehdr *)buf;
phdr = (Elf_Phdr *)(buf + ehdr->e_phoff);
loadsection = ehdr->e_phnum - 1;
if (ehdr->e_type != ET_EXEC ||
(phdr[loadsection].p_flags & 0x08000000) == 0)
goto done;
if (phdr[loadsection].p_type != PT_LOAD ||
((phdr[loadsection].p_flags & 0x08000000) == 0)) {
/* doesn't look like ours */
if (verbose)
fprintf(stderr, "mapped, %s id doesn't match %lx\n", name,
(long)(phdr[loadsection].p_vaddr));
goto done;
}
bzero(&phdr[loadsection], sizeof(Elf_Phdr));
ehdr->e_phnum--;
done:
munmap(buf, 8192);
return (0);
}
int
prebind_newfile(int infd, char *name, struct stat *st,
struct prebind_footer *footer)
{
struct timeval tv[2];
char *newname, *buf;
ssize_t len, wlen;
int outfd;
if (asprintf(&newname, "%s.XXXXXXXXXX", name) == -1) {
if (verbose)
warn("asprintf");
return (-1);
}
outfd = open(newname, O_CREAT|O_RDWR|O_TRUNC, 0600);
if (outfd == -1) {
warn("%s", newname);
free(newname);
return (-1);
}
buf = malloc(BUFSZ);
if (buf == NULL) {
if (verbose)
warn("malloc");
goto fail;
}
/* copy old file to new file */
lseek(infd, (off_t)0, SEEK_SET);
while (1) {
len = read(infd, buf, BUFSIZ);
if (len == -1) {
if (verbose)
warn("read");
free(buf);
goto fail;
}
if (len == 0)
break;
wlen = write(outfd, buf, len);
if (wlen != len) {
free(buf);
goto fail;
}
}
free(buf);
/* now back track, and delete the header */
if (prebind_remove_load_section(outfd, newname) == -1)
goto fail;
if (ftruncate(outfd, footer->orig_size) == -1)
goto fail;
/* move new file into place */
TIMESPEC_TO_TIMEVAL(&tv[0], &st->st_atimespec);
TIMESPEC_TO_TIMEVAL(&tv[1], &st->st_mtimespec);
if (futimes(outfd, tv) == -1)
goto fail;
if (fchown(outfd, st->st_uid, st->st_gid) == -1)
goto fail;
if (fchmod(outfd, st->st_mode) == -1)
goto fail;
if (fchflags(outfd, st->st_flags) == -1)
goto fail;
if (rename(newname, name) == -1)
goto fail;
return (outfd);
fail:
free(newname);
unlink(newname);
close(outfd);
return (-1);
}
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