From 1c6608bd92acfa3a4c269ccdcb92905a4e512813 Mon Sep 17 00:00:00 2001 From: Simon Glass Date: Sun, 18 Jul 2021 14:18:06 -0600 Subject: [PATCH] sandbox: tpm: Support extending a PCR multiple times It is fairly easy to handle this case and it makes the emulator more useful, since PCRs are commonly extended several times. Add support for this, using U-Boot's sha256 support. For now sandbox only supports a single PCR, but that is enough for the tests that currently exist. Signed-off-by: Simon Glass --- drivers/tpm/tpm2_tis_sandbox.c | 24 ++++++++++-------------- test/py/tests/test_tpm2.py | 18 +++++++++++++++++- 2 files changed, 27 insertions(+), 15 deletions(-) diff --git a/drivers/tpm/tpm2_tis_sandbox.c b/drivers/tpm/tpm2_tis_sandbox.c index 3c4bbcd..ac6eb14 100644 --- a/drivers/tpm/tpm2_tis_sandbox.c +++ b/drivers/tpm/tpm2_tis_sandbox.c @@ -11,6 +11,7 @@ #include #include #include +#include #include "sandbox_common.h" /* Hierarchies */ @@ -39,13 +40,6 @@ enum tpm2_cap_tpm_property { #define SANDBOX_TPM_PCR_NB 1 -static const u8 sandbox_extended_once_pcr[] = { - 0xf5, 0xa5, 0xfd, 0x42, 0xd1, 0x6a, 0x20, 0x30, - 0x27, 0x98, 0xef, 0x6e, 0xd3, 0x09, 0x97, 0x9b, - 0x43, 0x00, 0x3d, 0x23, 0x20, 0xd9, 0xf0, 0xe8, - 0xea, 0x98, 0x31, 0xa9, 0x27, 0x59, 0xfb, 0x4b, -}; - /* * Information about our TPM emulation. This is preserved in the sandbox * state file if enabled. @@ -407,15 +401,17 @@ static int sandbox_tpm2_extend(struct udevice *dev, int pcr_index, const u8 *extension) { struct sandbox_tpm2 *tpm = dev_get_priv(dev); - int i; + sha256_context ctx; + + /* Zero the PCR if this is the first use */ + if (!tpm->pcr_extensions[pcr_index]) + memset(tpm->pcr[pcr_index], '\0', TPM2_DIGEST_LEN); - /* Only simulate the first extensions from all '0' with only '0' */ - for (i = 0; i < TPM2_DIGEST_LEN; i++) - if (tpm->pcr[pcr_index][i] || extension[i]) - return TPM2_RC_FAILURE; + sha256_starts(&ctx); + sha256_update(&ctx, tpm->pcr[pcr_index], TPM2_DIGEST_LEN); + sha256_update(&ctx, extension, TPM2_DIGEST_LEN); + sha256_finish(&ctx, tpm->pcr[pcr_index]); - memcpy(tpm->pcr[pcr_index], sandbox_extended_once_pcr, - TPM2_DIGEST_LEN); tpm->pcr_extensions[pcr_index]++; return 0; diff --git a/test/py/tests/test_tpm2.py b/test/py/tests/test_tpm2.py index 70f906d..ac04f71 100644 --- a/test/py/tests/test_tpm2.py +++ b/test/py/tests/test_tpm2.py @@ -216,7 +216,9 @@ def test_tpm2_pcr_extend(u_boot_console): output = u_boot_console.run_command('echo $?') assert output.endswith('0') - read_pcr = u_boot_console.run_command('tpm2 pcr_read 0 0x%x' % ram) + # Read the value back into a different place so we can still use 'ram' as + # our zero bytes + read_pcr = u_boot_console.run_command('tpm2 pcr_read 0 0x%x' % (ram + 0x20)) output = u_boot_console.run_command('echo $?') assert output.endswith('0') assert 'f5 a5 fd 42 d1 6a 20 30 27 98 ef 6e d3 09 97 9b' in read_pcr @@ -226,6 +228,20 @@ def test_tpm2_pcr_extend(u_boot_console): new_updates = int(re.findall(r'\d+', str)[0]) assert (updates + 1) == new_updates + u_boot_console.run_command('tpm2 pcr_extend 0 0x%x' % ram) + output = u_boot_console.run_command('echo $?') + assert output.endswith('0') + + read_pcr = u_boot_console.run_command('tpm2 pcr_read 0 0x%x' % (ram + 0x20)) + output = u_boot_console.run_command('echo $?') + assert output.endswith('0') + assert '7a 05 01 f5 95 7b df 9c b3 a8 ff 49 66 f0 22 65' in read_pcr + assert 'f9 68 65 8b 7a 9c 62 64 2c ba 11 65 e8 66 42 f5' in read_pcr + + str = re.findall(r'\d+ known updates', read_pcr)[0] + new_updates = int(re.findall(r'\d+', str)[0]) + assert (updates + 2) == new_updates + @pytest.mark.buildconfigspec('cmd_tpm_v2') def test_tpm2_cleanup(u_boot_console): """Ensure the TPM is cleared from password or test related configuration.""" -- 2.7.4