mirror of
https://github.com/tillitis/tillitis-key1.git
synced 2024-10-01 01:45:38 -04:00
fw: Introduce an explicit state machine - changes protocol!
We introduce an explicit state machine (see README). With the new states we: - combine setting size and USS to a single command. - start the device app immediatiely when having receceived the last data chunk and returning the digest. - Loop forever and wait for the stick to be removed if we end up in unknown state. Signed-off-by: Michael Cardell Widerkrantz <mc@tillitis.se>
This commit is contained in:
Michael Cardell Widerkrantz
parent
2fa1ffb8e7
commit
c80dc53027
@ -18,6 +18,54 @@ If your available `objcopy` and `size` commands is anything other than
|
||||
the default `llvm-objcopy` and `llvm-size` define `OBJCOPY` and `SIZE`
|
||||
to whatever they're called on your system.
|
||||
|
||||
## Firmware state machine
|
||||
|
||||
States:
|
||||
|
||||
- `initial` - At start.
|
||||
- `init_loading` - Reset app digest, size, `USS` and load address.
|
||||
- `loading` - Expect more app data or a reset by `LoadApp()`.
|
||||
- `run` - Computes CDI and starts the device app.
|
||||
|
||||
Commands in state `initial`:
|
||||
|
||||
| *command* | *next state* |
|
||||
|--------------------|----------------|
|
||||
| NameVersion() | unchanged |
|
||||
| GetUDI() | unchanged |
|
||||
| LoadApp(size, uss) | `init_loading` |
|
||||
| | |
|
||||
|
||||
Commands in `init_loading`:
|
||||
|
||||
| *command* | *next state* |
|
||||
|--------------------|----------------|
|
||||
| NameVersion() | unchanged |
|
||||
| GetUDI() | unchanged |
|
||||
| LoadApp(size, uss) | `init_loading` |
|
||||
| LoadAppData(data) | `loading` |
|
||||
| | |
|
||||
|
||||
Commands in `loading`:
|
||||
|
||||
| *command* | *next state* |
|
||||
|--------------------|----------------------------------|
|
||||
| NameVersion() | unchanged |
|
||||
| GetUDI() | unchanged |
|
||||
| LoadApp(size, uss) | `init_loading` |
|
||||
| LoadAppData(data) | `loading` or `run` on last chunk |
|
||||
| | |
|
||||
|
||||
Behaviour:
|
||||
|
||||
- NameVersion: identifies stick.
|
||||
- GetUDI: returns the Unique Device ID with vendor id, product id,
|
||||
revision, serial number.
|
||||
- LoadApp(size, uss): Start loading an app with this size and user
|
||||
supplied secret.
|
||||
- LoadAppData(data): Load chunk of data of app. When last data chunk
|
||||
is received we compute and return the digest.
|
||||
|
||||
## Using QEMU
|
||||
|
||||
Checkout the `tk1` branch of [our version of the
|
||||
|
||||
@ -60,9 +60,10 @@ static void print_digest(uint8_t *md)
|
||||
}
|
||||
|
||||
// CDI = blake2s(uds, blake2s(app), uss)
|
||||
static void compute_cdi(uint8_t digest[32], uint8_t uss[32])
|
||||
static void compute_cdi(uint8_t digest[32], uint8_t use_uss, uint8_t uss[32])
|
||||
{
|
||||
uint32_t local_cdi[8];
|
||||
int len;
|
||||
|
||||
// To protect UDS we use a special firmware-only RAM for both
|
||||
// the in parameter to blake2s and the blake2s context.
|
||||
@ -70,11 +71,16 @@ static void compute_cdi(uint8_t digest[32], uint8_t uss[32])
|
||||
// Only word aligned access to UDS
|
||||
wordcpy((void *)fw_ram, (void *)uds, 8);
|
||||
memcpy((void *)fw_ram + 32, digest, 32);
|
||||
memcpy((void *)fw_ram + 64, uss, 32);
|
||||
if (use_uss != 0) {
|
||||
memcpy((void *)fw_ram + 64, uss, 32);
|
||||
len = 96;
|
||||
} else {
|
||||
len = 64;
|
||||
}
|
||||
|
||||
blake2s_ctx *secure_ctx = (blake2s_ctx *)(fw_ram + 96);
|
||||
blake2s_ctx *secure_ctx = (blake2s_ctx *)(fw_ram + len);
|
||||
|
||||
blake2s((void *)local_cdi, 32, NULL, 0, (const void *)fw_ram, 96,
|
||||
blake2s((void *)local_cdi, 32, NULL, 0, (const void *)fw_ram, len,
|
||||
secure_ctx);
|
||||
|
||||
// Write over the firmware-only RAM
|
||||
@ -84,6 +90,13 @@ static void compute_cdi(uint8_t digest[32], uint8_t uss[32])
|
||||
wordcpy((void *)cdi, (void *)local_cdi, 8);
|
||||
}
|
||||
|
||||
enum state {
|
||||
FW_STATE_INITIAL,
|
||||
FW_STATE_INIT_LOADING,
|
||||
FW_STATE_LOADING,
|
||||
FW_STATE_RUN
|
||||
};
|
||||
|
||||
int main()
|
||||
{
|
||||
uint32_t local_name0 = *name0;
|
||||
@ -94,179 +107,34 @@ int main()
|
||||
uint8_t rsp[CMDLEN_MAXBYTES];
|
||||
uint8_t *loadaddr = (uint8_t *)TK1_APP_ADDR;
|
||||
int left = 0; // Bytes left to receive
|
||||
uint8_t use_uss = FALSE;
|
||||
uint8_t uss[32] = {0};
|
||||
uint8_t digest[32] = {0};
|
||||
enum state state = FW_STATE_INITIAL;
|
||||
|
||||
print_hw_version(local_name0, local_name1, local_ver);
|
||||
|
||||
for (;;) {
|
||||
// blocking; fw flashing white while waiting for cmd
|
||||
uint8_t in = readbyte_ledflash(LED_WHITE, 800000);
|
||||
|
||||
if (parseframe(in, &hdr) == -1) {
|
||||
puts("Couldn't parse header\n");
|
||||
continue;
|
||||
}
|
||||
|
||||
memset(cmd, 0, CMDLEN_MAXBYTES);
|
||||
// Read firmware command: Blocks!
|
||||
read(cmd, hdr.len);
|
||||
|
||||
// Is it for us?
|
||||
if (hdr.endpoint != DST_FW) {
|
||||
puts("Message not meant for us\n");
|
||||
continue;
|
||||
}
|
||||
|
||||
// Reset response buffer
|
||||
memset(rsp, 0, CMDLEN_MAXBYTES);
|
||||
|
||||
// Min length is 1 byte so this should always be here
|
||||
switch (cmd[0]) {
|
||||
case FW_CMD_NAME_VERSION:
|
||||
puts("cmd: name-version\n");
|
||||
|
||||
if (hdr.len != 1) {
|
||||
// Bad length - give them an empty response
|
||||
fwreply(hdr, FW_RSP_NAME_VERSION, rsp);
|
||||
break;
|
||||
}
|
||||
|
||||
memcpy(rsp, (uint8_t *)&local_name0, 4);
|
||||
memcpy(rsp + 4, (uint8_t *)&local_name1, 4);
|
||||
memcpy(rsp + 8, (uint8_t *)&local_ver, 4);
|
||||
|
||||
fwreply(hdr, FW_RSP_NAME_VERSION, rsp);
|
||||
switch (state) {
|
||||
case FW_STATE_INITIAL:
|
||||
break;
|
||||
|
||||
case FW_CMD_GET_UDI:
|
||||
puts("FW_CMD_GET_UDI\n");
|
||||
if (hdr.len != 1) {
|
||||
// Bad cmd length
|
||||
rsp[0] = STATUS_BAD;
|
||||
fwreply(hdr, FW_RSP_GET_UDI, rsp);
|
||||
break;
|
||||
}
|
||||
rsp[0] = STATUS_OK;
|
||||
uint32_t udi_words[2];
|
||||
wordcpy(udi_words, (void *)udi, 2);
|
||||
memcpy(rsp + 1, udi_words, 2 * 4);
|
||||
fwreply(hdr, FW_RSP_GET_UDI, rsp);
|
||||
break;
|
||||
|
||||
case FW_CMD_LOAD_USS:
|
||||
puts("cmd: load-uss\n");
|
||||
|
||||
if (hdr.len != 128) {
|
||||
// Bad cmd length
|
||||
rsp[0] = STATUS_BAD;
|
||||
fwreply(hdr, FW_RSP_LOAD_USS, rsp);
|
||||
break;
|
||||
}
|
||||
|
||||
memcpy(uss, cmd + 1, 32);
|
||||
|
||||
rsp[0] = STATUS_OK;
|
||||
fwreply(hdr, FW_RSP_LOAD_USS, rsp);
|
||||
break;
|
||||
|
||||
case FW_CMD_LOAD_APP_SIZE:
|
||||
puts("cmd: load-app-size\n");
|
||||
|
||||
if (hdr.len != 32) {
|
||||
// Bad length
|
||||
rsp[0] = STATUS_BAD;
|
||||
fwreply(hdr, FW_RSP_LOAD_APP_SIZE, rsp);
|
||||
break;
|
||||
}
|
||||
|
||||
// cmd[1..4] contains the size.
|
||||
uint32_t local_app_size = cmd[1] + (cmd[2] << 8) +
|
||||
(cmd[3] << 16) +
|
||||
(cmd[4] << 24);
|
||||
|
||||
puts("app size: ");
|
||||
putinthex(local_app_size);
|
||||
lf();
|
||||
|
||||
if (local_app_size > TK1_APP_MAX_SIZE) {
|
||||
rsp[0] = STATUS_BAD;
|
||||
fwreply(hdr, FW_RSP_LOAD_APP_SIZE, rsp);
|
||||
break;
|
||||
}
|
||||
|
||||
*app_size = local_app_size;
|
||||
case FW_STATE_INIT_LOADING:
|
||||
*app_addr = 0;
|
||||
// Clear digest as GET_APP_DIGEST returns it even if it
|
||||
// has not been calculated
|
||||
memset(digest, 0, 32);
|
||||
left = *app_size;
|
||||
|
||||
// Reset where to start loading the program
|
||||
loadaddr = (uint8_t *)TK1_APP_ADDR;
|
||||
left = *app_size;
|
||||
|
||||
rsp[0] = STATUS_OK;
|
||||
fwreply(hdr, FW_RSP_LOAD_APP_SIZE, rsp);
|
||||
break;
|
||||
|
||||
case FW_CMD_LOAD_APP_DATA:
|
||||
puts("cmd: load-app-data\n");
|
||||
|
||||
if (hdr.len != 128 || *app_size == 0 ||
|
||||
*app_addr != 0) {
|
||||
// Bad length, or app_size not yet set, or
|
||||
// app_addr already set (fully loaded!)
|
||||
rsp[0] = STATUS_BAD;
|
||||
fwreply(hdr, FW_RSP_LOAD_APP_DATA, rsp);
|
||||
break;
|
||||
}
|
||||
|
||||
int nbytes;
|
||||
if (left > 127) {
|
||||
nbytes = 127;
|
||||
} else {
|
||||
nbytes = left;
|
||||
}
|
||||
memcpy(loadaddr, cmd + 1, nbytes);
|
||||
loadaddr += nbytes;
|
||||
left -= nbytes;
|
||||
|
||||
if (left == 0) {
|
||||
puts("Fully loaded ");
|
||||
putinthex(*app_size);
|
||||
lf();
|
||||
|
||||
*app_addr = TK1_APP_ADDR;
|
||||
// Get the Blake2S digest of the app - store it
|
||||
// for later queries
|
||||
blake2s_ctx ctx;
|
||||
|
||||
blake2s(digest, 32, NULL, 0,
|
||||
(const void *)*app_addr, *app_size,
|
||||
&ctx);
|
||||
print_digest(digest);
|
||||
|
||||
// CDI = hash(uds, hash(app), uss)
|
||||
compute_cdi(digest, uss);
|
||||
}
|
||||
|
||||
rsp[0] = STATUS_OK;
|
||||
fwreply(hdr, FW_RSP_LOAD_APP_DATA, rsp);
|
||||
case FW_STATE_LOADING:
|
||||
break;
|
||||
|
||||
case FW_CMD_RUN_APP:
|
||||
puts("cmd: run-app\n");
|
||||
case FW_STATE_RUN:
|
||||
*app_addr = TK1_APP_ADDR;
|
||||
|
||||
if (hdr.len != 1 || *app_size == 0 || *app_addr == 0) {
|
||||
// Bad cmd length, or app_size or app_addr are
|
||||
// not yet set
|
||||
rsp[0] = STATUS_BAD;
|
||||
fwreply(hdr, FW_RSP_RUN_APP, rsp);
|
||||
break;
|
||||
}
|
||||
|
||||
rsp[0] = STATUS_OK;
|
||||
fwreply(hdr, FW_RSP_RUN_APP, rsp);
|
||||
// CDI = hash(uds, hash(app), uss)
|
||||
compute_cdi(digest, use_uss, uss);
|
||||
|
||||
// Flip over to application mode
|
||||
*switch_app = 1;
|
||||
@ -293,11 +161,160 @@ int main()
|
||||
// clang-format on
|
||||
break; // This is never reached!
|
||||
|
||||
case FW_CMD_GET_APP_DIGEST:
|
||||
puts("cmd: get-app-digest\n");
|
||||
default:
|
||||
// Unknown state!?
|
||||
puts("Unknown firmware state 0x");
|
||||
puthex(state);
|
||||
lf();
|
||||
|
||||
memcpy(rsp, &digest, 32);
|
||||
fwreply(hdr, FW_RSP_GET_APP_DIGEST, rsp);
|
||||
asm volatile("forever:;"
|
||||
"j forever;");
|
||||
break; // Not reached
|
||||
}
|
||||
|
||||
// blocking; fw flashing white while waiting for cmd
|
||||
uint8_t in = readbyte_ledflash(LED_WHITE, 800000);
|
||||
|
||||
if (parseframe(in, &hdr) == -1) {
|
||||
puts("Couldn't parse header\n");
|
||||
continue;
|
||||
}
|
||||
|
||||
memset(cmd, 0, CMDLEN_MAXBYTES);
|
||||
// Now we know the size of the cmd frame, read it all
|
||||
read(cmd, hdr.len);
|
||||
|
||||
// Is it for us?
|
||||
if (hdr.endpoint != DST_FW) {
|
||||
puts("Message not meant for us\n");
|
||||
continue;
|
||||
}
|
||||
|
||||
// Reset response buffer
|
||||
memset(rsp, 0, CMDLEN_MAXBYTES);
|
||||
|
||||
// Min length is 1 byte so this should always be here
|
||||
switch (cmd[0]) {
|
||||
case FW_CMD_NAME_VERSION:
|
||||
puts("cmd: name-version\n");
|
||||
if (hdr.len != 1) {
|
||||
// Bad length - give them an empty response
|
||||
fwreply(hdr, FW_RSP_NAME_VERSION, rsp);
|
||||
break;
|
||||
}
|
||||
|
||||
memcpy(rsp, (uint8_t *)&local_name0, 4);
|
||||
memcpy(rsp + 4, (uint8_t *)&local_name1, 4);
|
||||
memcpy(rsp + 8, (uint8_t *)&local_ver, 4);
|
||||
fwreply(hdr, FW_RSP_NAME_VERSION, rsp);
|
||||
// state unchanged
|
||||
break;
|
||||
|
||||
case FW_CMD_GET_UDI:
|
||||
puts("cmd: get-udi\n");
|
||||
if (hdr.len != 1) {
|
||||
// Bad cmd length
|
||||
rsp[0] = STATUS_BAD;
|
||||
fwreply(hdr, FW_RSP_GET_UDI, rsp);
|
||||
break;
|
||||
}
|
||||
|
||||
rsp[0] = STATUS_OK;
|
||||
uint32_t udi_words[2];
|
||||
wordcpy(udi_words, (void *)udi, 2);
|
||||
memcpy(rsp + 1, udi_words, 2 * 4);
|
||||
fwreply(hdr, FW_RSP_GET_UDI, rsp);
|
||||
// state unchanged
|
||||
break;
|
||||
|
||||
case FW_CMD_LOAD_APP:
|
||||
puts("cmd: load-app(size, uss)\n");
|
||||
if (hdr.len != 128) {
|
||||
// Bad length
|
||||
rsp[0] = STATUS_BAD;
|
||||
fwreply(hdr, FW_RSP_LOAD_APP, rsp);
|
||||
break;
|
||||
}
|
||||
|
||||
// cmd[1..4] contains the size.
|
||||
uint32_t local_app_size = cmd[1] + (cmd[2] << 8) +
|
||||
(cmd[3] << 16) +
|
||||
(cmd[4] << 24);
|
||||
|
||||
puts("app size: ");
|
||||
putinthex(local_app_size);
|
||||
lf();
|
||||
|
||||
if (local_app_size > TK1_APP_MAX_SIZE) {
|
||||
rsp[0] = STATUS_BAD;
|
||||
fwreply(hdr, FW_RSP_LOAD_APP, rsp);
|
||||
break;
|
||||
}
|
||||
|
||||
*app_size = local_app_size;
|
||||
|
||||
// Do we have a USS at all?
|
||||
if (cmd[5] != 0) {
|
||||
// Yes
|
||||
use_uss = TRUE;
|
||||
memcpy(uss, cmd + 6, 32);
|
||||
} else {
|
||||
use_uss = FALSE;
|
||||
}
|
||||
|
||||
rsp[0] = STATUS_OK;
|
||||
fwreply(hdr, FW_RSP_LOAD_APP, rsp);
|
||||
|
||||
state = FW_STATE_INIT_LOADING;
|
||||
break;
|
||||
|
||||
case FW_CMD_LOAD_APP_DATA:
|
||||
puts("cmd: load-app-data\n");
|
||||
if (hdr.len != 128 || (state != FW_STATE_INIT_LOADING &&
|
||||
state != FW_STATE_LOADING)) {
|
||||
// Bad cmd length or state
|
||||
rsp[0] = STATUS_BAD;
|
||||
fwreply(hdr, FW_RSP_LOAD_APP_DATA, rsp);
|
||||
break;
|
||||
}
|
||||
|
||||
int nbytes;
|
||||
if (left > 127) {
|
||||
nbytes = 127;
|
||||
} else {
|
||||
nbytes = left;
|
||||
}
|
||||
memcpy(loadaddr, cmd + 1, nbytes);
|
||||
loadaddr += nbytes;
|
||||
left -= nbytes;
|
||||
|
||||
if (left == 0) {
|
||||
puts("Fully loaded ");
|
||||
putinthex(*app_size);
|
||||
lf();
|
||||
|
||||
// Compute Blake2S digest of the app, storing
|
||||
// it for FW_STATE_RUN
|
||||
blake2s_ctx ctx;
|
||||
|
||||
blake2s(digest, 32, NULL, 0,
|
||||
(const void *)TK1_APP_ADDR, *app_size,
|
||||
&ctx);
|
||||
print_digest(digest);
|
||||
|
||||
// And return the digest in final response
|
||||
rsp[0] = STATUS_OK;
|
||||
memcpy(&rsp[1], &digest, 32);
|
||||
fwreply(hdr, FW_RSP_LOAD_APP_DATA_READY, rsp);
|
||||
|
||||
state = FW_STATE_RUN;
|
||||
break;
|
||||
}
|
||||
|
||||
rsp[0] = STATUS_OK;
|
||||
fwreply(hdr, FW_RSP_LOAD_APP_DATA, rsp);
|
||||
|
||||
state = FW_STATE_LOADING;
|
||||
break;
|
||||
|
||||
default:
|
||||
|
||||
@ -71,12 +71,7 @@ void fwreply(struct frame_header hdr, enum fwcmd rspcode, uint8_t *buf)
|
||||
nbytes = 32;
|
||||
break;
|
||||
|
||||
case FW_RSP_LOAD_USS:
|
||||
len = LEN_4;
|
||||
nbytes = 4;
|
||||
break;
|
||||
|
||||
case FW_RSP_LOAD_APP_SIZE:
|
||||
case FW_RSP_LOAD_APP:
|
||||
len = LEN_4;
|
||||
nbytes = 4;
|
||||
break;
|
||||
@ -86,12 +81,7 @@ void fwreply(struct frame_header hdr, enum fwcmd rspcode, uint8_t *buf)
|
||||
nbytes = 4;
|
||||
break;
|
||||
|
||||
case FW_RSP_RUN_APP:
|
||||
len = LEN_4;
|
||||
nbytes = 4;
|
||||
break;
|
||||
|
||||
case FW_RSP_GET_APP_DIGEST:
|
||||
case FW_RSP_LOAD_APP_DATA_READY:
|
||||
len = LEN_128;
|
||||
nbytes = 128;
|
||||
break;
|
||||
|
||||
@ -26,21 +26,15 @@ enum cmdlen {
|
||||
|
||||
// clang-format off
|
||||
enum fwcmd {
|
||||
FW_CMD_NAME_VERSION = 0x01,
|
||||
FW_RSP_NAME_VERSION = 0x02,
|
||||
FW_CMD_LOAD_APP_SIZE = 0x03,
|
||||
FW_RSP_LOAD_APP_SIZE = 0x04,
|
||||
FW_CMD_LOAD_APP_DATA = 0x05,
|
||||
FW_RSP_LOAD_APP_DATA = 0x06,
|
||||
FW_CMD_RUN_APP = 0x07,
|
||||
FW_RSP_RUN_APP = 0x08,
|
||||
FW_CMD_GET_APP_DIGEST = 0x09,
|
||||
FW_CMD_LOAD_USS = 0x0a,
|
||||
FW_RSP_LOAD_USS = 0x0b,
|
||||
FW_CMD_GET_UDI = 0x0c,
|
||||
FW_RSP_GET_UDI = 0x0d,
|
||||
/* ... */
|
||||
FW_RSP_GET_APP_DIGEST = 0x10, // encoded as 0x10 for backwards compatibility
|
||||
FW_CMD_NAME_VERSION = 0x01,
|
||||
FW_RSP_NAME_VERSION = 0x02,
|
||||
FW_CMD_LOAD_APP = 0x03,
|
||||
FW_RSP_LOAD_APP = 0x04,
|
||||
FW_CMD_LOAD_APP_DATA = 0x05,
|
||||
FW_RSP_LOAD_APP_DATA = 0x06,
|
||||
FW_RSP_LOAD_APP_DATA_READY = 0x07,
|
||||
FW_CMD_GET_UDI = 0x08,
|
||||
FW_RSP_GET_UDI = 0x09,
|
||||
};
|
||||
// clang-format on
|
||||
|
||||
|
||||
@ -16,4 +16,7 @@ typedef unsigned long size_t;
|
||||
|
||||
#define NULL ((char *)0)
|
||||
|
||||
#define FALSE 0
|
||||
#define TRUE !FALSE
|
||||
|
||||
#endif
|
||||
|
||||
Loading…
Reference in New Issue
Block a user