/*
* Copyright (C) 2016 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include <variant/variant.h>
#include <bl.h>
#include <plat/cmsis.h>
#include <plat/gpio.h>
#include <nanohub/sha2.h>
#include <nanohub/aes.h>
#include <nanohub/rsa.h>
#include <nanohub/nanohub.h>
#include <printf.h>
#include <string.h>
static uint32_t blVerifyOsImage(const uint8_t *addr, struct OsUpdateHdr **start, uint32_t *size);
//for comms protocol
#define BL_SYNC_IN 0x5A
#define BL_ACK 0x79
#define BL_NAK 0x1F
#define BL_SYNC_OUT 0xA5
#define BL_CMD_GET 0x00
#define BL_CMD_READ_MEM 0x11
#define BL_CMD_WRITE_MEM 0x31
#define BL_CMD_ERASE 0x44
#define BL_CMD_GET_SIZES 0xEE /* our own command. reports: {u32 osSz, u32 sharedSz, u32 eeSz} all in big endian */
#define BL_CMD_UPDATE_FINISHED 0xEF /* our own command. attempts to verify the update -> ACK/NAK. MUST be called after upload to mark it as completed */
#define BL_ERROR 0xDEADBEAF /* returned in place of command in case of exchange errors */
#define BL_SHARED_AREA_FAKE_ERASE_BLK 0xFFF0
#define BL_SHARED_AREA_FAKE_ADDR 0x50000000
//linker provides these
extern uint32_t __pubkeys_start[];
extern uint32_t __pubkeys_end[];
extern uint8_t __eedata_start[];
extern uint8_t __eedata_end[];
extern uint8_t __code_start[];
extern uint8_t __code_end[];
extern uint8_t __shared_start[];
extern uint8_t __shared_end[];
enum BlFlashType
{
BL_FLASH_BL,
BL_FLASH_EEDATA,
BL_FLASH_KERNEL,
BL_FLASH_SHARED
};
static const struct blFlashTable // For erase code, we need to know which page a given memory address is in
{
uint8_t *address;
uint32_t length;
uint32_t type;
} mBlFlashTable[] =
#ifndef BL_FLASH_TABLE
{
{ (uint8_t *)(&BL), 0x04000, BL_FLASH_BL },
{ (uint8_t *)(__eedata_start), 0x04000, BL_FLASH_EEDATA },
{ (uint8_t *)(__eedata_start + 0x04000), 0x04000, BL_FLASH_EEDATA },
{ (uint8_t *)(__code_start), 0x04000, BL_FLASH_KERNEL },
{ (uint8_t *)(__code_start + 0x04000), 0x10000, BL_FLASH_KERNEL },
{ (uint8_t *)(__shared_start), 0x20000, BL_FLASH_SHARED },
{ (uint8_t *)(__shared_start + 0x20000), 0x20000, BL_FLASH_SHARED },
{ (uint8_t *)(__shared_start + 0x40000), 0x20000, BL_FLASH_SHARED },
};
#else
BL_FLASH_TABLE;
#endif
static const char mOsUpdateMagic[] = OS_UPDT_MAGIC;
#ifdef DEBUG_UART_PIN
static bool blLogPutcharF(void *userData, char ch)
{
if (ch == '\n')
gpioBitbangedUartOut('\r');
gpioBitbangedUartOut(ch);
return true;
}
void blLog(const char *str, ...)
{
va_list vl;
va_start(vl, str);
cvprintf(blLogPutcharF, NULL, str, vl);
va_end(vl);
}
#else
#define blLog(...)
#endif
static uint32_t blExtApiGetVersion(void)
{
return BL_VERSION_CUR;
}
static bool blProgramFlash(uint8_t *dst, const uint8_t *src, uint32_t length, uint32_t key1, uint32_t key2)
{
const uint32_t sector_cnt = sizeof(mBlFlashTable) / sizeof(struct blFlashTable);
uint32_t offset, i, j = 0;
uint8_t *ptr;
if (((length == 0)) ||
((0xFFFFFFFF - (uint32_t)dst) < (length - 1)) ||
((dst < mBlFlashTable[0].address)) ||
((dst + length) > (mBlFlashTable[sector_cnt-1].address +
mBlFlashTable[sector_cnt-1].length))) {
return false;
}
// compute which flash block we are starting from
for (i = 0; i < sector_cnt; i++) {
if (dst >= mBlFlashTable[i].address &&
dst < (mBlFlashTable[i].address + mBlFlashTable[i].length)) {
break;
}
}
// now loop through all the flash blocks and see if we have to do any
// 0 -> 1 transitions of a bit. If so, return false
// 1 -> 0 transitions of a bit do not require an erase
offset = (uint32_t)(dst - mBlFlashTable[i].address);
ptr = mBlFlashTable[i].address;
while (j < length && i < sector_cnt) {
if (offset == mBlFlashTable[i].length) {
i++;
offset = 0;
ptr = mBlFlashTable[i].address;
}
if ((ptr[offset] & src[j]) != src[j]) {
return false;
} else {
j++;
offset++;
}
}
if (!blPlatProgramFlash(dst, src, length, key1, key2))
return false;
return !memcmp(dst, src, length);
}
static void blExtApiGetSnum(uint32_t *snum, uint32_t length)
{
blGetSnum(snum, length);
}
static bool blProgramTypedArea(uint8_t *dst, const uint8_t *src, uint32_t length, uint32_t type, uint32_t key1, uint32_t key2)
{
const uint32_t sector_cnt = sizeof(mBlFlashTable) / sizeof(struct blFlashTable);
uint32_t i;
for (i = 0; i < sector_cnt; i++) {
if ((dst >= mBlFlashTable[i].address &&
dst < (mBlFlashTable[i].address + mBlFlashTable[i].length)) ||
(dst < mBlFlashTable[i].address &&
(dst + length > mBlFlashTable[i].address))) {
if (mBlFlashTable[i].type != type)
return false;
}
}
return blProgramFlash(dst, src, length, key1, key2);
}
static bool blExtApiProgramSharedArea(uint8_t *dst, const uint8_t *src, uint32_t length, uint32_t key1, uint32_t key2)
{
return blProgramTypedArea(dst, src, length, BL_FLASH_SHARED, key1, key2);
}
static bool blExtApiProgramEe(uint8_t *dst, const uint8_t *src, uint32_t length, uint32_t key1, uint32_t key2)
{
return blProgramTypedArea(dst, src, length, BL_FLASH_EEDATA, key1, key2);
}
static bool blEraseTypedArea(uint32_t type, uint32_t key1, uint32_t key2)
{
const uint32_t sector_cnt = sizeof(mBlFlashTable) / sizeof(struct blFlashTable);
uint32_t i, erase_cnt = 0;
uint8_t erase_mask[sector_cnt];
for (i = 0; i < sector_cnt; i++) {
if (mBlFlashTable[i].type == type) {
erase_mask[i] = 1;
erase_cnt++;
} else {
erase_mask[i] = 0;
}
}
if (erase_cnt)
blEraseSectors(sector_cnt, erase_mask, key1, key2);
return true; //we assume erase worked
}
static bool blExtApiEraseSharedArea(uint32_t key1, uint32_t key2)
{
return blEraseTypedArea(BL_FLASH_SHARED, key1, key2);
}
static uint32_t blVerifyOsUpdate(struct OsUpdateHdr **start, uint32_t *size)
{
uint32_t ret;
int i;
for (i = 0; i < BL_SCAN_OFFSET; i += 4) {
ret = blVerifyOsImage(__shared_start + i, start, size);
if (ret != OS_UPDT_HDR_CHECK_FAILED)
break;
}
return ret;
}
static uint32_t blExtApiVerifyOsUpdate(void)
{
return blVerifyOsUpdate(NULL, NULL);
}
static void blExtApiReboot(void)
{
blReboot();
}
static const uint32_t *blExtApiGetRsaKeyInfo(uint32_t *numKeys)
{
uint32_t numWords = __pubkeys_end - __pubkeys_start;
if (numWords % RSA_WORDS) // something is wrong
return NULL;
*numKeys = numWords / RSA_WORDS;
return __pubkeys_start;
}
static const uint32_t* blExtApiSigPaddingVerify(const uint32_t *rsaResult)
{
uint32_t i;
//all but first and last word of padding MUST have no zero bytes
for (i = SHA2_HASH_WORDS + 1; i < RSA_WORDS - 1; i++) {
if (!(uint8_t)(rsaResult[i] >> 0))
return NULL;
if (!(uint8_t)(rsaResult[i] >> 8))
return NULL;
if (!(uint8_t)(rsaResult[i] >> 16))
return NULL;
if (!(uint8_t)(rsaResult[i] >> 24))
return NULL;
}
//first padding word must have all nonzero bytes except low byte
if ((rsaResult[SHA2_HASH_WORDS] & 0xff) || !(rsaResult[SHA2_HASH_WORDS] & 0xff00) || !(rsaResult[SHA2_HASH_WORDS] & 0xff0000) || !(rsaResult[SHA2_HASH_WORDS] & 0xff000000))
return NULL;
//last padding word must have 0x0002 in top 16 bits and nonzero random bytes in lower bytes
if ((rsaResult[RSA_WORDS - 1] >> 16) != 2)
return NULL;
if (!(rsaResult[RSA_WORDS - 1] & 0xff00) || !(rsaResult[RSA_WORDS - 1] & 0xff))
return NULL;
return rsaResult;
}
static void blApplyVerifiedUpdate(const struct OsUpdateHdr *os) //only called if an update has been found to exist and be valid, signed, etc!
{
//copy shared to code, and if successful, erase shared area
if (blEraseTypedArea(BL_FLASH_KERNEL, BL_FLASH_KEY1, BL_FLASH_KEY2))
if (blProgramTypedArea(__code_start, (const uint8_t*)(os + 1), os->size, BL_FLASH_KERNEL, BL_FLASH_KEY1, BL_FLASH_KEY2))
(void)blExtApiEraseSharedArea(BL_FLASH_KEY1, BL_FLASH_KEY2);
}
static void blWriteMark(struct OsUpdateHdr *hdr, uint32_t mark)
{
uint8_t dstVal = mark;
(void)blExtApiProgramSharedArea(&hdr->marker, &dstVal, sizeof(hdr->marker), BL_FLASH_KEY1, BL_FLASH_KEY2);
}
static void blUpdateMark(uint32_t old, uint32_t new)
{
struct OsUpdateHdr *hdr = (struct OsUpdateHdr *)__shared_start;
if (hdr->marker != old)
return;
blWriteMark(hdr, new);
}
static uint32_t blVerifyOsImage(const uint8_t *addr, struct OsUpdateHdr **start, uint32_t *size)
{
const uint32_t *rsaKey, *osSigHash, *osSigPubkey, *ourHash, *rsaResult, *expectedHash = NULL;
struct OsUpdateHdr *hdr = (struct OsUpdateHdr*)addr;
struct OsUpdateHdr cpy;
uint32_t i, numRsaKeys = 0, rsaStateVar1, rsaStateVar2, rsaStep = 0;
const uint8_t *updateBinaryData;
bool isValid = false;
struct Sha2state sha;
struct RsaState rsa;
uint32_t ret = OS_UPDT_HDR_CHECK_FAILED;
const uint32_t overhead = sizeof(*hdr) + 2 * RSA_WORDS;
// header does not fit or is not aligned
if (addr < __shared_start || addr > (__shared_end - overhead) || ((uintptr_t)addr & 3))
return OS_UPDT_HDR_CHECK_FAILED;
// image does not fit
if (hdr->size > (__shared_end - addr - overhead))
return OS_UPDT_HDR_CHECK_FAILED;
// OS magic does not match
if (memcmp(hdr->magic, mOsUpdateMagic, sizeof(hdr->magic)) != 0)
return OS_UPDT_HDR_CHECK_FAILED;
// we don't allow shortcuts on success path, but we want to fail quickly
if (hdr->marker == OS_UPDT_MARKER_INVALID)
return OS_UPDT_HDR_MARKER_INVALID;
// download did not finish
if (hdr->marker == OS_UPDT_MARKER_INPROGRESS)
return OS_UPDT_HDR_MARKER_INVALID;
//get pointers
updateBinaryData = (const uint8_t*)(hdr + 1);
osSigHash = (const uint32_t*)(updateBinaryData + hdr->size);
osSigPubkey = osSigHash + RSA_WORDS;
//make sure the pub key is known
for (i = 0, rsaKey = blExtApiGetRsaKeyInfo(&numRsaKeys); i < numRsaKeys; i++, rsaKey += RSA_WORDS) {
if (memcmp(rsaKey, osSigPubkey, RSA_BYTES) == 0)
break;
}
if (i == numRsaKeys) {
ret = OS_UPDT_UNKNOWN_PUBKEY;
//signed with an unknown key -> fail
goto fail;
}
//decode sig using pubkey
do {
rsaResult = rsaPubOpIterative(&rsa, osSigHash, osSigPubkey, &rsaStateVar1, &rsaStateVar2, &rsaStep);
} while (rsaStep);
if (!rsaResult) {
//decode fails -> invalid sig
ret = OS_UPDT_INVALID_SIGNATURE;
goto fail;
}
//verify padding
expectedHash = blExtApiSigPaddingVerify(rsaResult);
if (!expectedHash) {
//padding check fails -> invalid sig
ret = OS_UPDT_INVALID_SIGNATURE_HASH;
goto fail;
}
//hash the update
sha2init(&sha);
memcpy(&cpy, hdr, sizeof(cpy));
cpy.marker = OS_UPDT_MARKER_INPROGRESS;
sha2processBytes(&sha, &cpy, sizeof(cpy));
sha2processBytes(&sha, (uint8_t*)(hdr + 1), hdr->size);
ourHash = sha2finish(&sha);
//verify hash match
if (memcmp(expectedHash, ourHash, SHA2_HASH_SIZE) != 0) {
//hash does not match -> data tampered with
ret = OS_UPDT_INVALID_SIGNATURE_HASH; // same error; do not disclose nature of hash problem
goto fail;
}
//it is valid
isValid = true;
ret = OS_UPDT_SUCCESS;
if (start)
*start = hdr;
if (size)
*size = hdr->size;
fail:
//mark it appropriately
blWriteMark(hdr, isValid ? OS_UPDT_MARKER_VERIFIED : OS_UPDT_MARKER_INVALID);
return ret;
}
static inline bool blUpdateVerify()
{
return blVerifyOsImage(__shared_start, NULL, NULL) == OS_UPDT_SUCCESS;
}
static uint8_t blLoaderRxByte()
{
return blSpiTxRxByte(0);
}
static void blLoaderTxByte(uint32_t val)
{
blSpiTxRxByte(val);
}
static void blLoaderTxBytes(const void *data, uint32_t len)
{
const uint8_t *buf = (const uint8_t*)data;
blLoaderTxByte(len - 1);
while (len--)
blLoaderTxByte(*buf++);
}
static bool blLoaderSendSyncOut()
{
return blSpiTxRxByte(BL_SYNC_OUT) == BL_SYNC_IN;
}
static bool blLoaderSendAck(bool ack)
{
blLoaderRxByte();
blLoaderTxByte(ack ? BL_ACK : BL_NAK);
return blLoaderRxByte() == BL_ACK;
}
static uint32_t blLoaderRxCmd()
{
uint8_t cmd = blLoaderRxByte();
uint8_t cmdNot = blSpiTxRxByte(BL_ACK);
return (cmd ^ cmdNot) == 0xFF ? cmd : BL_ERROR;
}
static void blLoader(bool force)
{
bool seenErase = false;
uint32_t nextAddr = 0;
uint32_t expectedSize = 0;
blSetup();
//if int pin is not low, do not bother any further
if (blHostActive() || force) {
blConfigIo();
//if we saw a sync, do the bootloader thing
if (blSyncWait(BL_SYNC_IN)) {
static const uint8_t supportedCmds[] = {BL_CMD_GET, BL_CMD_READ_MEM, BL_CMD_WRITE_MEM, BL_CMD_ERASE, BL_CMD_GET_SIZES, BL_CMD_UPDATE_FINISHED};
uint32_t allSizes[] = {__builtin_bswap32(__code_end - __code_start), __builtin_bswap32(__shared_end - __shared_start), __builtin_bswap32(__eedata_end - __eedata_start)};
bool ack = true; //we ack the sync
ack = blLoaderSendSyncOut();
//loop forever listening to commands
while (1) {
uint32_t sync, cmd, addr = 0, len, checksum = 0, i;
uint8_t data[256];
//send ack or NAK for last thing
if (!blLoaderSendAck(ack))
goto out;
while ((sync = blLoaderRxByte()) != BL_SYNC_IN);
cmd = blLoaderRxCmd();
ack = false;
if (sync == BL_SYNC_IN && cmd != BL_ERROR)
switch (cmd) {
case BL_CMD_GET:
//ACK the command
(void)blLoaderSendAck(true);
blLoaderTxBytes(supportedCmds, sizeof(supportedCmds));
ack = true;
break;
case BL_CMD_READ_MEM:
if (!seenErase) //no reading till we erase the shared area (this way we do not leak encrypted apps' plaintexts)
break;
//ACK the command
(void)blLoaderSendAck(true);
//get address
for (i = 0; i < 4; i++) {
uint32_t byte = blLoaderRxByte();
checksum ^= byte;
addr = (addr << 8) + byte;
}
//reject addresses outside of our fake area or on invalid checksum
if (blLoaderRxByte() != checksum || addr < BL_SHARED_AREA_FAKE_ADDR || addr - BL_SHARED_AREA_FAKE_ADDR > __shared_end - __shared_start)
break;
//ack the address
(void)blLoaderSendAck(true);
//get the length
len = blLoaderRxByte();
//reject invalid checksum
if (blLoaderRxByte() != (uint8_t)~len || addr + len - BL_SHARED_AREA_FAKE_ADDR > __shared_end - __shared_start)
break;
len++;
//reject reads past the end of the shared area
if (addr + len - BL_SHARED_AREA_FAKE_ADDR > __shared_end - __shared_start)
break;
//ack the length
(void)blLoaderSendAck(true);
//read the data & send it
blLoaderTxBytes(__shared_start + addr - BL_SHARED_AREA_FAKE_ADDR, len);
ack = true;
break;
case BL_CMD_WRITE_MEM:
if (!seenErase) //no writing till we erase the shared area (this way we do not purposefully modify encrypted apps' plaintexts in a nefarious fashion)
break;
//ACK the command
(void)blLoaderSendAck(true);
//get address
for (i = 0; i < 4; i++) {
uint32_t byte = blLoaderRxByte();
checksum ^= byte;
addr = (addr << 8) + byte;
}
//reject addresses outside of our fake area or on invalid checksum
if (blLoaderRxByte() != checksum ||
addr < BL_SHARED_AREA_FAKE_ADDR ||
addr - BL_SHARED_AREA_FAKE_ADDR > __shared_end - __shared_start)
break;
addr -= BL_SHARED_AREA_FAKE_ADDR;
if (addr != nextAddr)
break;
//ack the address
(void)blLoaderSendAck(true);
//get the length
checksum = len = blLoaderRxByte();
len++;
//get bytes
for (i = 0; i < len; i++) {
uint32_t byte = blLoaderRxByte();
checksum ^= byte;
data[i] = byte;
}
//reject writes that takes out outside fo shared area or invalid checksums
if (blLoaderRxByte() != checksum || addr + len > __shared_end - __shared_start)
break;
// OBSOLETE: superseded by sequential contiguous write requirement
//if (addr && addr < sizeof(struct OsUpdateHdr))
// break;
//a write starting at zero must be big enough to contain a full OS update header
if (!addr) {
const struct OsUpdateHdr *hdr = (const struct OsUpdateHdr*)data;
//verify it is at least as big as the header
if (len < sizeof(struct OsUpdateHdr))
break;
//check for magic
for (i = 0; i < sizeof(hdr->magic) && hdr->magic[i] == mOsUpdateMagic[i]; i++);
//verify magic check passed & marker is properly set to inprogress
if (i != sizeof(hdr->magic) || hdr->marker != OS_UPDT_MARKER_INPROGRESS)
break;
expectedSize = sizeof(*hdr) + hdr->size + 2 * RSA_BYTES;
}
if (addr + len > expectedSize)
break;
//do it
ack = blExtApiProgramSharedArea(__shared_start + addr, data, len, BL_FLASH_KEY1, BL_FLASH_KEY2);
blResetRxData();
nextAddr += len;
break;
case BL_CMD_ERASE:
//ACK the command
(void)blLoaderSendAck(true);
//get address
for (i = 0; i < 2; i++) {
uint32_t byte = blLoaderRxByte();
checksum ^= byte;
addr = (addr << 8) + byte;
}
//reject addresses that are not our magic address or on invalid checksum
if (blLoaderRxByte() != checksum || addr != BL_SHARED_AREA_FAKE_ERASE_BLK)
break;
//do it
ack = blExtApiEraseSharedArea(BL_FLASH_KEY1, BL_FLASH_KEY2);
if (ack) {
seenErase = true;
nextAddr = 0;
expectedSize = 0;
}
blResetRxData();
break;
case BL_CMD_GET_SIZES:
//ACK the command
(void)blLoaderSendAck(true);
blLoaderTxBytes(allSizes, sizeof(allSizes));
break;
case BL_CMD_UPDATE_FINISHED:
blUpdateMark(OS_UPDT_MARKER_INPROGRESS, OS_UPDT_MARKER_DOWNLOADED);
ack = blUpdateVerify();
break;
}
}
}
}
out:
blCleanup();
}
void blMain(uint32_t appBase)
{
bool forceLoad = false;
blLog("NanohubOS bootloader up @ %p\n", &blMain);
//enter SPI loader if requested
do {
uint32_t res;
struct OsUpdateHdr *os;
blLoader(forceLoad);
res = blVerifyOsUpdate(&os, NULL);
if (res == OS_UPDT_SUCCESS)
blApplyVerifiedUpdate(os);
else if (res != OS_UPDT_HDR_CHECK_FAILED)
blExtApiEraseSharedArea(BL_FLASH_KEY1, BL_FLASH_KEY2);
forceLoad = true;
} while (*(volatile uint32_t*)appBase == 0xFFFFFFFF);
}
const struct BlApiTable __attribute__((section(".blapi"))) __BL_API =
{
.blGetVersion = &blExtApiGetVersion,
.blReboot = &blExtApiReboot,
.blGetSnum = &blExtApiGetSnum,
.blProgramShared = &blExtApiProgramSharedArea,
.blEraseShared = &blExtApiEraseSharedArea,
.blProgramEe = &blExtApiProgramEe,
.blGetPubKeysInfo = &blExtApiGetRsaKeyInfo,
.blRsaPubOpIterative = &rsaPubOpIterative,
.blSha2init = &sha2init,
.blSha2processBytes = &sha2processBytes,
.blSha2finish = &sha2finish,
.blAesInitForEncr = &aesInitForEncr,
.blAesInitForDecr = &aesInitForDecr,
.blAesEncr = &aesEncr,
.blAesDecr = &aesDecr,
.blAesCbcInitForEncr = &aesCbcInitForEncr,
.blAesCbcInitForDecr = &aesCbcInitForDecr,
.blAesCbcEncr = &aesCbcEncr,
.blAesCbcDecr = &aesCbcDecr,
.blSigPaddingVerify = &blExtApiSigPaddingVerify,
.blVerifyOsUpdate = &blExtApiVerifyOsUpdate,
};