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fw: Only allow a specific app to start from first flash

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Store size and app digest in ROM and compare to what we are booting.
This commit is contained in:
Michael Cardell Widerkrantz 2025-03-24 15:53:37 +01:00
parent 5cba9b3f7e
commit b6e05828e9
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GPG Key ID: D3DB3DDF57E704E5
1 changed files with 23 additions and 4 deletions
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27
hw/application_fpga/fw/tk1/main.c
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@ -43,6 +43,19 @@ static volatile struct reset *resetinfo = (volatile struct reset *)TK1_
struct partition_table part_table;
// Locked down what app can start from first flash slot to be exactly
// this size, producing this digest.
//
// To update this, compute the BLAKE2s digest of the app.bin and
// insert the size in bytes.
#define APP_SIZE_SLOT0 21684
// BLAKE2s digest of testloadapp.bin
const uint8_t allowed_app_digest[32] = {
0x3a, 0x34, 0x6f, 0x1f, 0xb7, 0x7f, 0xa6, 0x71, 0x9b, 0x69, 0x8,
0x36, 0xa0, 0x5, 0xe, 0x26, 0x48, 0x8d, 0xab, 0x6a, 0x51, 0xa6,
0xe1, 0x18, 0x53, 0xa3, 0x64, 0xc6, 0x5b, 0x42, 0x49, 0xb7,
};
// Context for the loading of a TKey program
struct context {
uint32_t left; // Bytes left to receive
@ -557,14 +570,12 @@ int main(void)
assert(1 != 2);
}
#if defined(SIMULATION)
run(&ctx);
#endif
// TODO Lie and tell filesystem we have a 128 kiB device app
// on flash.
part_table.pre_app_data[0].size = 0x20000;
// Hardocde size of slot 0
part_table.pre_app_data[0].size = APP_SIZE_SLOT0;
// part_table.pre_app_data[1].size = 0x20000;
// TODO Just start something from flash without looking in
@ -616,6 +627,14 @@ int main(void)
break;
}
if (ctx.flash_slot == 0) {
print_digest(allowed_app_digest);
if (!memeq(ctx.digest, allowed_app_digest, 32)) {
puts(IO_CDC, "app not allowed!\r\n");
assert(1 == 2);
}
}
// CDI = hash(uds, hash(app), uss)
compute_cdi(ctx.digest, ctx.use_uss, ctx.uss);