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rockbox/firmware/target/arm/pp/mi4-loader.c

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/***************************************************************************
* __________ __ ___.
* Open \______ \ ____ ____ | | _\_ |__ _______ ___
* Source | _// _ \_/ ___\| |/ /| __ \ / _ \ \/ /
* Jukebox | | ( <_> ) \___| < | \_\ ( <_> > < <
* Firmware |____|_ /\____/ \___ >__|_ \|___ /\____/__/\_ \
* \/ \/ \/ \/ \/
*
* Copyright (C) 2006 by Barry Wardell
* Copyright (C) 2020 by William Wilgus [MULTIBOOT]
*
* Based on Rockbox iriver bootloader by Linus Nielsen Feltzing
* and the ipodlinux bootloader by Daniel Palffy and Bernard Leach
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
* KIND, either express or implied.
*
****************************************************************************/
#include <stdbool.h>
#include <stdio.h>
#include "config.h"
#include "mi4-loader.h"
#include "loader_strerror.h"
#include "crc32.h"
#include "file.h"
#if defined(HAVE_BOOTDATA)
#include "system.h"
#include "bootdata.h"
/* Write bootdata into location in FIRMWARE marked by magic header
* Assumes buffer is already loaded with the firmware image
* We just need to find the location and write data into the
* payload region along with the crc for later verification and use.
* Returns payload len on success,
* On error returns EKEY_NOT_FOUND
*/
int write_bootdata(unsigned char* buf, int len, unsigned int boot_volume)
{
struct boot_data_t bl_boot_data;
struct boot_data_t *fw_boot_data = NULL;
int search_len = MIN(len, BOOT_DATA_SEARCH_SIZE) - sizeof(struct boot_data_t);
int payload_len = EKEY_NOT_FOUND;
/* search for boot data header prior to search_len */
for(int i = 0;i < search_len;i++)
{
fw_boot_data = (struct boot_data_t*) &buf[i];
if (fw_boot_data->magic[0] != BOOT_DATA_MAGIC0 ||
fw_boot_data->magic[1] != BOOT_DATA_MAGIC1)
continue;
memset(&bl_boot_data.payload, 0, BOOT_DATA_PAYLOAD_SIZE);
bl_boot_data.boot_volume = boot_volume;
memset(fw_boot_data->payload, 0, fw_boot_data->length);
/* determine maximum bytes we can write to firmware
BOOT_DATA_PAYLOAD_SIZE is the size the bootloader expects */
payload_len = MIN(BOOT_DATA_PAYLOAD_SIZE, fw_boot_data->length);
fw_boot_data->length = payload_len;
/* copy data to FIRMWARE bootdata struct */
memcpy(fw_boot_data->payload, &bl_boot_data.payload, payload_len);
/* crc will be used within the firmware to check validity of bootdata */
fw_boot_data->crc = crc_32(fw_boot_data->payload, payload_len, 0xffffffff);
break;
}
return payload_len;
}
#endif /* HAVE_BOOTDATA */
#ifdef HAVE_MULTIBOOT /* defined by config.h */
/* Check in root of this <volume> for rockbox_main.<playername>
* if this file empty or there is a single slash '/'
* buf = '<volume#>/<rootdir>/<firmware(name)>\0'
* If instead '/<*DIRECTORY*>' is supplied
* addpath will be set to this DIRECTORY buf =
* '/<volume#>/addpath/<rootdir>/<firmware(name)>\0'
* On error returns Negative number or 0
* On success returns bytes from snprintf
* and generated path will be placed in buf
* note: if supplied buffer is too small return will be
* the number of bytes that would have been written
*/
int get_redirect_dir(char* buf, int buffer_size, int volume,
const char* rootdir, const char* firmware)
{
int fd;
int f_offset;
char add_path[MAX_PATH];
/* Check in root of volume for rockbox_main.<playername> redirect */
snprintf(add_path, sizeof(add_path), "/<%d>/"BOOT_REDIR, volume);
fd = open(add_path, O_RDONLY);
if (fd < 0)
return EFILE_NOT_FOUND;
/*clear add_path for re-use*/
memset(add_path, 0, sizeof(add_path));
f_offset = read(fd, add_path,sizeof(add_path));
close(fd);
for(int i = f_offset - 1;i > 0; i--)
{
/* strip control chars < SPACE or all if path doesn't start with '/' */
if (add_path[i] < 0x20 || add_path[0] != '/')
add_path[i] = '\0';
}
/* if '/add_path' is specified in rockbox_main.<playername>
path is /<vol#>/add_path/rootdir/firmwarename
if add_path is empty or '/' is missing from beginning
path is /<vol#>/rootdir/firmwarename
*/
return snprintf(buf, buffer_size, "/<%d>%s/%s/%s", volume, add_path,
rootdir, firmware);
}
#endif /* HAVE_MULTIBOOT */
static inline unsigned int le2int(unsigned char* buf)
{
int32_t res = (buf[3] << 24) | (buf[2] << 16) | (buf[1] << 8) | buf[0];
return res;
}
static inline void int2le(unsigned int val, unsigned char* addr)
{
addr[0] = val & 0xFF;
addr[1] = (val >> 8) & 0xff;
addr[2] = (val >> 16) & 0xff;
addr[3] = (val >> 24) & 0xff;
}
static struct tea_key tea_keytable[] = {
{ "default" , { 0x20d36cc0, 0x10e8c07d, 0xc0e7dcaa, 0x107eb080 } },
{ "sansa", { 0xe494e96e, 0x3ee32966, 0x6f48512b, 0xa93fbb42 } },
{ "sansa_gh", { 0xd7b10538, 0xc662945b, 0x1b3fce68, 0xf389c0e6 } },
{ "sansa_103", { 0x1d29ddc0, 0x2579c2cd, 0xce339e1a, 0x75465dfe } },
{ "rhapsody", { 0x7aa9c8dc, 0xbed0a82a, 0x16204cc7, 0x5904ef38 } },
{ "p610", { 0x950e83dc, 0xec4907f9, 0x023734b9, 0x10cfb7c7 } },
{ "p640", { 0x220c5f23, 0xd04df68e, 0x431b5e25, 0x4dcc1fa1 } },
{ "virgin", { 0xe83c29a1, 0x04862973, 0xa9b3f0d4, 0x38be2a9c } },
{ "20gc_eng", { 0x0240772c, 0x6f3329b5, 0x3ec9a6c5, 0xb0c9e493 } },
{ "20gc_fre", { 0xbede8817, 0xb23bfe4f, 0x80aa682d, 0xd13f598c } },
{ "elio_p722", { 0x6af3b9f8, 0x777483f5, 0xae8181cc, 0xfa6d8a84 } },
{ "c200", { 0xbf2d06fa, 0xf0e23d59, 0x29738132, 0xe2d04ca7 } },
{ "c200_103", { 0x2a7968de, 0x15127979, 0x142e60a7, 0xe49c1893 } },
{ "c200_106", { 0xa913d139, 0xf842f398, 0x3e03f1a6, 0x060ee012 } },
{ "view", { 0x70e19bda, 0x0c69ea7d, 0x2b8b1ad1, 0xe9767ced } },
{ "sa9200", { 0x33ea0236, 0x9247bdc5, 0xdfaedf9f, 0xd67c9d30 } },
{ "hdd1630/hdd63x0", { 0x04543ced, 0xcebfdbad, 0xf7477872, 0x0d12342e } },
{ "vibe500", { 0xe3a66156, 0x77c6b67a, 0xe821dca5, 0xca8ca37c } },
};
/*
tea_decrypt() from http://en.wikipedia.org/wiki/Tiny_Encryption_Algorithm
"Following is an adaptation of the reference encryption and decryption
routines in C, released into the public domain by David Wheeler and
Roger Needham:"
*/
/* NOTE: The mi4 version of TEA uses a different initial value to sum compared
to the reference implementation and the main loop is 8 iterations, not
32.
*/
static void tea_decrypt(uint32_t* v0, uint32_t* v1, uint32_t* k) {
uint32_t sum=0xF1BBCDC8, i; /* set up */
uint32_t delta=0x9E3779B9; /* a key schedule constant */
uint32_t k0=k[0], k1=k[1], k2=k[2], k3=k[3]; /* cache key */
for(i=0; i<8; i++) { /* basic cycle start */
*v1 -= ((*v0<<4) + k2) ^ (*v0 + sum) ^ ((*v0>>5) + k3);
*v0 -= ((*v1<<4) + k0) ^ (*v1 + sum) ^ ((*v1>>5) + k1);
sum -= delta; /* end cycle */
}
}
/* mi4 files are encrypted in 64-bit blocks (two little-endian 32-bit
integers) and the key is incremented after each block
*/
static void tea_decrypt_buf(unsigned char* src,
unsigned char* dest,
size_t n, uint32_t * key)
{
uint32_t v0, v1;
unsigned int i;
for (i = 0; i < (n / 8); i++) {
v0 = le2int(src);
v1 = le2int(src+4);
tea_decrypt(&v0, &v1, key);
int2le(v0, dest);
int2le(v1, dest+4);
src += 8;
dest += 8;
/* Now increment the key */
key[0]++;
if (key[0]==0) {
key[1]++;
if (key[1]==0) {
key[2]++;
if (key[2]==0) {
key[3]++;
}
}
}
}
}
static int tea_find_key(struct mi4header_t *mi4header, unsigned char* buf)
{
unsigned int i;
uint32_t key[4];
uint32_t keyinc;
unsigned char magic_dec[8];
int key_found = -1;
unsigned int magic_location = mi4header->length-4;
int unaligned = 0;
if ( (magic_location % 8) != 0 )
{
unaligned = 1;
magic_location -= 4;
}
for (i=0; i < NUM_KEYS && (key_found<0) ; i++) {
key[0] = tea_keytable[i].key[0];
key[1] = tea_keytable[i].key[1];
key[2] = tea_keytable[i].key[2];
key[3] = tea_keytable[i].key[3];
/* Now increment the key */
keyinc = (magic_location-mi4header->plaintext)/8;
if ((key[0]+keyinc) < key[0]) key[1]++;
key[0] += keyinc;
if (key[1]==0) key[2]++;
if (key[2]==0) key[3]++;
/* Decrypt putative magic */
tea_decrypt_buf(&buf[magic_location], magic_dec, 8, key);
if (le2int(&magic_dec[4*unaligned]) == 0xaa55aa55)
{
key_found = i;
}
}
return key_found;
}
/* Load mi4 format firmware image from a FULLY QUALIFIED PATH */
static int load_mi4_filename(unsigned char* buf,
const char* filename,
unsigned int buffer_size)
{
int fd;
struct mi4header_t mi4header;
int rc;
unsigned long sum;
fd = open(filename, O_RDONLY);
if(fd < 0)
return EFILE_NOT_FOUND;
read(fd, &mi4header, MI4_HEADER_SIZE);
/* MI4 file size */
if ((mi4header.mi4size-MI4_HEADER_SIZE) > buffer_size)
{
close(fd);
return EFILE_TOO_BIG;
}
/* Load firmware file */
lseek(fd, MI4_HEADER_SIZE, SEEK_SET);
rc = read(fd, buf, mi4header.mi4size-MI4_HEADER_SIZE);
close(fd);
if(rc < (int)mi4header.mi4size-MI4_HEADER_SIZE)
return EREAD_IMAGE_FAILED;
/* Check CRC32 to see if we have a valid file */
sum = crc_32r (buf, mi4header.mi4size - MI4_HEADER_SIZE, 0);
if(sum != mi4header.crc32)
return EBAD_CHKSUM;
if( (mi4header.plaintext + MI4_HEADER_SIZE) != mi4header.mi4size)
{
/* Load encrypted firmware */
int key_index = tea_find_key(&mi4header, buf);
if (key_index < 0)
return EINVALID_FORMAT;
/* Plaintext part is already loaded */
buf += mi4header.plaintext;
/* Decrypt in-place */
tea_decrypt_buf(buf, buf,
mi4header.mi4size-(mi4header.plaintext+MI4_HEADER_SIZE),
tea_keytable[key_index].key);
/* Check decryption was successfull */
if(le2int(&buf[mi4header.length-mi4header.plaintext-4]) != 0xaa55aa55)
return EREAD_IMAGE_FAILED;
}
return mi4header.mi4size - MI4_HEADER_SIZE;
}
/* Load mi4 format firmware image */
int load_mi4(unsigned char* buf, const char* firmware, unsigned int buffer_size)
{
int ret = EFILE_NOT_FOUND;
char filename[MAX_PATH+2];
/* only filename passed */
if (firmware[0] != '/')
{
#ifdef HAVE_MULTIBOOT /* defined by config.h */
/* checks <volumes> highest index to lowest for redirect file
* 0 is the default boot volume, it is not checked here
* if found <volume>/rockbox_main.<playername> and firmware
* has a bootdata region this firmware will be loaded */
for (unsigned int i = NUM_VOLUMES - 1; i > 0 && ret < 0; i--)
{
if (get_redirect_dir(filename, sizeof(filename), i,
BOOTDIR, firmware) > 0)
{
ret = load_mi4_filename(buf, filename, buffer_size);
/* if firmware has no boot_data don't load from external drive */
if (write_bootdata(buf, ret, i) <= 0)
ret = EKEY_NOT_FOUND;
}
/* if ret is valid breaks from loop to continue loading */
}
#endif
if (ret < 0) /* Check default volume, no valid firmware file loaded yet */
{
/* First check in BOOTDIR */
snprintf(filename, sizeof(filename), BOOTDIR "/%s",firmware);
ret = load_mi4_filename(buf, filename, buffer_size);
if (ret < 0)
{
/* Check in root dir */
snprintf(filename, sizeof(filename),"/%s",firmware);
ret = load_mi4_filename(buf, filename, buffer_size);
}
#ifdef HAVE_BOOTDATA
/* 0 is the default boot volume */
write_bootdata(buf, ret, 0);
#endif
}
}
else /* full path passed ROLO etc.*/
ret = load_mi4_filename(buf, firmware, buffer_size);
return ret;
}
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