* Copyright (c) 2006 Elad Efrat <elad@NetBSD.org>

/* $NetBSD: paxctl.c,v 1.13 2023/06/23 01:56:21 rin Exp $ */

/*-
* Copyright (c) 2006 Elad Efrat <[email protected]>
* Copyright (c) 2008 Christos Zoulas <[email protected]>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#if HAVE_NBTOOL_CONFIG_H
#include "nbtool_config.h"
#endif

#include <sys/cdefs.h>
#ifndef lint
#ifdef __RCSID
__RCSID("$NetBSD: paxctl.c,v 1.13 2023/06/23 01:56:21 rin Exp $");
#endif
#endif /* not lint */

#include <sys/types.h>
#ifdef HAVE_NBTOOL_CONFIG_H
#include "../../sys/sys/exec_elf.h"
#else
#include <elf.h>
#endif
#include <stdio.h>
#include <err.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>

static void usage(void) __dead;
static uint32_t pax_flag(char);
static int pax_flags_sane(uint32_t);
static int pax_haveflags(uint32_t);
static void pax_printflags(const char *, int, uint32_t);

#ifndef ELF_NOTE_TYPE_PAX_TAG
/* NetBSD-specific note type: PaX. There should be 1 NOTE per executable.
section. desc is a 32 bit bitmask */
#define ELF_NOTE_TYPE_PAX_TAG 3
#define ELF_NOTE_PAX_MPROTECT 0x01 /* Force enable MPROTECT */
#define ELF_NOTE_PAX_NOMPROTECT 0x02 /* Force disable MPROTECT */
#define ELF_NOTE_PAX_GUARD 0x04 /* Force enable Segvguard */
#define ELF_NOTE_PAX_NOGUARD 0x08 /* Force disable Segvguard */
#define ELF_NOTE_PAX_ASLR 0x10 /* Force enable ASLR */
#define ELF_NOTE_PAX_NOASLR 0x20 /* Force disable ASLR */
#define ELF_NOTE_PAX_NAMESZ 4
#define ELF_NOTE_PAX_NAME "PaX\0"
#define ELF_NOTE_PAX_DESCSZ 4
#endif
#ifndef __arraycount
#define __arraycount(a) (sizeof(a) / sizeof(a[0]))
#endif

static const struct paxflag {
char mark;
const char *name;
uint32_t bits;
} flags[] = {
{ 'A', "ASLR, explicit enable",
ELF_NOTE_PAX_ASLR },
{ 'a', "ASLR, explicit disable",
ELF_NOTE_PAX_NOASLR },
{ 'G', "Segvguard, explicit enable",
ELF_NOTE_PAX_GUARD },
{ 'g', "Segvguard, explicit disable",
ELF_NOTE_PAX_NOGUARD },
{ 'M', "mprotect(2) restrictions, explicit enable",
ELF_NOTE_PAX_MPROTECT },
{ 'm', "mprotect(2) restrictions, explicit disable",
ELF_NOTE_PAX_NOMPROTECT },
};

static void
usage(void)
{
(void)fprintf(stderr,
"Usage: %s [ -0 | <-|+><A|a|G|g|M|m> ] <file> ...\n",
#if HAVE_NBTOOL_CONFIG_H
"paxctl"
#else
getprogname()
#endif
);
exit(1);
}

static uint32_t
pax_flag(char s)
{
size_t i;

if (s == '\0')
return (uint32_t)-1;

for (i = 0; i < __arraycount(flags); i++)
if (s == flags[i].mark)
return flags[i].bits;

return (uint32_t)-1;
}

static int
pax_flags_sane(uint32_t f)
{
size_t i;

for (i = 0; i < __arraycount(flags) - 1; i += 2) {
uint32_t g = flags[i].bits | flags[i+1].bits;
if ((f & g) == g)
return 0;
}

return 1;
}

static int
pax_haveflags(uint32_t f)
{
size_t i;

for (i = 0; i < __arraycount(flags); i++)
if (f & flags[i].bits)
return (1);

return (0);
}

static void
pax_printflags(const char *name, int many, uint32_t f)
{
size_t i;

for (i = 0; i < __arraycount(flags); i++)
if (f & flags[i].bits) {
if (many)
(void)printf("%s: ", name);
(void)printf(" %c: %s\n",
flags[i].mark, flags[i].name);
}
}

static int
process_one(const char *name, uint32_t add_flags, uint32_t del_flags,
int clear, int list, int many)
{
union {
Elf32_Ehdr h32;
Elf64_Ehdr h64;
} e;
union {
Elf32_Shdr h32;
Elf64_Shdr h64;
} s;
union {
Elf32_Nhdr h32;
Elf64_Nhdr h64;
} n;
#define SWAP(a) (swap == 0 ? (a) : \
/*LINTED*/(sizeof(a) == 1 ? (a) : \
/*LINTED*/(sizeof(a) == 2 ? bswap16(a) : \
/*LINTED*/(sizeof(a) == 4 ? bswap32(a) : \
/*LINTED*/(sizeof(a) == 8 ? bswap64(a) : (abort(), (a)))))))
#define EH(field) (size == 32 ? SWAP(e.h32.field) : SWAP(e.h64.field))
#define SH(field) (size == 32 ? SWAP(s.h32.field) : SWAP(s.h64.field))
#define NH(field) (size == 32 ? SWAP(n.h32.field) : SWAP(n.h64.field))
#define SHSIZE (size == 32 ? sizeof(s.h32) : sizeof(s.h64))
#define NHSIZE (size == 32 ? sizeof(n.h32) : sizeof(n.h64))
struct {
char name[ELF_NOTE_PAX_NAMESZ];
uint32_t flags;
} pax_tag;
int fd, size, ok = 0, flagged = 0, swap, error = 1;
size_t i;

fd = open(name, list ? O_RDONLY: O_RDWR, 0);
if (fd == -1) {
warn("Can't open `%s'", name);
return error;
}

if (read(fd, &e, sizeof(e)) != sizeof(e)) {
warn("Can't read ELF header from `%s'", name);
goto out;
}

if (memcmp(e.h32.e_ident, ELFMAG, SELFMAG) != 0) {
warnx("Bad ELF magic from `%s' (maybe it's not an ELF?)", name);
goto out;
}

if (e.h32.e_ehsize == sizeof(e.h32)) {
size = 32;
swap = 0;
} else if (e.h64.e_ehsize == sizeof(e.h64)) {
size = 64;
swap = 0;
} else if (bswap16(e.h32.e_ehsize) == sizeof(e.h32)) {
size = 32;
swap = 1;
} else if (bswap16(e.h64.e_ehsize) == sizeof(e.h64)) {
size = 64;
swap = 1;
} else {
warnx("Bad ELF size %d from `%s' (maybe it's not an ELF?)",
(int)e.h32.e_ehsize, name);
goto out;
}

for (i = 0; i < EH(e_shnum); i++) {
if ((size_t)pread(fd, &s, SHSIZE,
(off_t)EH(e_shoff) + i * SHSIZE) != SHSIZE) {
warn("Can't read section header data from `%s'", name);
goto out;
}

if (SH(sh_type) != SHT_NOTE)
continue;

if (pread(fd, &n, NHSIZE, (off_t)SH(sh_offset)) != NHSIZE) {
warn("Can't read note header from `%s'", name);
goto out;
}
if (NH(n_type) != ELF_NOTE_TYPE_PAX_TAG ||
NH(n_descsz) != ELF_NOTE_PAX_DESCSZ ||
NH(n_namesz) != ELF_NOTE_PAX_NAMESZ)
continue;
if (pread(fd, &pax_tag, sizeof(pax_tag), SH(sh_offset) + NHSIZE)
!= sizeof(pax_tag)) {
warn("Can't read pax_tag from `%s'", name);
goto out;
}
if (memcmp(pax_tag.name, ELF_NOTE_PAX_NAME,
sizeof(pax_tag.name)) != 0) {
warn("Unknown pax_tag name `%*.*s' from `%s'",
ELF_NOTE_PAX_NAMESZ, ELF_NOTE_PAX_NAMESZ,
pax_tag.name, name);
goto out;
}
ok = 1;

if (list) {
if (!pax_haveflags(SWAP(pax_tag.flags)))
break;

if (!pax_flags_sane(SWAP(pax_tag.flags)))
warnx("Current flags 0x%x don't make sense",
(uint32_t)SWAP(pax_tag.flags));

if (many)
(void)printf("%s: ", name);
(void)printf("PaX flags:\n");

pax_printflags(name, many, SWAP(pax_tag.flags));
flagged = 1;
break;
}

if (clear) {
pax_tag.flags = 0;
} else {
pax_tag.flags |= SWAP(add_flags);
pax_tag.flags &= SWAP(~del_flags);
}

if (!pax_flags_sane(SWAP(pax_tag.flags))) {
warnx("New flags 0x%x don't make sense",
(uint32_t)SWAP(pax_tag.flags));
goto out;
}

if (pwrite(fd, &pax_tag, sizeof(pax_tag),
(off_t)SH(sh_offset) + NHSIZE) != sizeof(pax_tag))
warn("Can't modify flags on `%s'", name);
break;
}

if (!ok) {
warnx("Could not find an ELF PaX SHT_NOTE section in `%s'",
name);
goto out;
}

error = 0;
if (list && !flagged) {
if (many)
(void)printf("%s: ", name);
(void)printf("No PaX flags.\n");
}
out:
(void)close(fd);
return error;
}

int
main(int argc, char **argv)
{
char *opt;
int i, clear = 0, list = 0, bad = 0, many, minus;
uint32_t add_flags = 0, del_flags = 0;

setprogname(argv[0]);

if (argc < 2)
usage();

for (i = 1; i < argc; i++) {
opt = argv[i];

if (strcmp(opt, "-0") == 0) {
clear = 1;
continue;
}

if (*opt == '-' || *opt == '+') {
uint32_t t;
minus = 0;

while (*opt) {
switch (*opt) {
case '+':
minus = 0;
opt++;
break;
case '-':
minus = 1;
opt++;
break;
case ',':
opt++;
break;
default:
t = pax_flag(*opt++);
if (t == (uint32_t)-1)
usage();
if (minus)
del_flags |= t;
else
add_flags |= t;
break;
}
}
} else
break;
}

if (i == argc)
usage();

switch ((add_flags != 0 || del_flags != 0) + clear) {
case 0:
list = 1;
break;
case 1:
break;
default:
usage();
}

many = i != argc - 1;
for (; i < argc; i++) {
bad |= process_one(argv[i], add_flags, del_flags,
clear, list, many);
}

return bad ? EXIT_FAILURE : 0;
}