Messages in this thread | | | Date | Mon, 27 Feb 2023 08:58:37 -0600 | Subject | Re: [PATCH v2] tpm: disable hwrng for fTPM on some AMD designs | From | Mario Limonciello <> |
| |
On 2/27/23 08:55, Guenter Roeck wrote: > On Mon, Feb 20, 2023 at 12:07:28PM -0600, Mario Limonciello wrote: >> AMD has issued an advisory indicating that having fTPM enabled in >> BIOS can cause "stuttering" in the OS. This issue has been fixed >> in newer versions of the fTPM firmware, but it's up to system >> designers to decide whether to distribute it. >> >> This issue has existed for a while, but is more prevalent starting >> with kernel 6.1 because commit b006c439d58db ("hwrng: core - start >> hwrng kthread also for untrusted sources") started to use the fTPM >> for hwrng by default. However, all uses of /dev/hwrng result in >> unacceptable stuttering. >> >> So, simply disable registration of the defective hwrng when detecting >> these faulty fTPM versions. As this is caused by faulty firmware, it >> is plausible that such a problem could also be reproduced by other TPM >> interactions, but this hasn't been shown by any user's testing or reports. >> >> It is hypothesized to be triggered more frequently by the use of the RNG >> because userspace software will fetch random numbers regularly. >> >> Intentionally continue to register other TPM functionality so that users >> that rely upon PCR measurements or any storage of data will still have >> access to it. If it's found later that another TPM functionality is >> exacerbating this problem a module parameter it can be turned off entirely >> and a module parameter can be introduced to allow users who rely upon >> fTPM functionality to turn it on even though this problem is present. >> >> Link: https://www.amd.com/en/support/kb/faq/pa-410 >> Link: https://bugzilla.kernel.org/show_bug.cgi?id=216989 >> Link: https://lore.kernel.org/all/20230209153120.261904-1-Jason@zx2c4.com/ >> Fixes: b006c439d58d ("hwrng: core - start hwrng kthread also for untrusted sources") >> Cc: stable@vger.kernel.org >> Cc: Jarkko Sakkinen <jarkko@kernel.org> >> Cc: Thorsten Leemhuis <regressions@leemhuis.info> >> Cc: James Bottomley <James.Bottomley@hansenpartnership.com> >> Co-developed-by: Jason A. Donenfeld <Jason@zx2c4.com> >> Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com> >> Signed-off-by: Mario Limonciello <mario.limonciello@amd.com> >> --- >> v1->v2: >> * Minor style from Jarkko's feedback >> * Move comment above function >> * Explain further in commit message >> --- >> drivers/char/tpm/tpm-chip.c | 61 ++++++++++++++++++++++++++++++- >> drivers/char/tpm/tpm.h | 73 +++++++++++++++++++++++++++++++++++++ >> 2 files changed, 133 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/char/tpm/tpm-chip.c b/drivers/char/tpm/tpm-chip.c >> index 741d8f3e8fb3..1b066d7a6e21 100644 >> --- a/drivers/char/tpm/tpm-chip.c >> +++ b/drivers/char/tpm/tpm-chip.c >> @@ -512,6 +512,64 @@ static int tpm_add_legacy_sysfs(struct tpm_chip *chip) >> return 0; >> } >> >> +/* >> + * Some AMD fTPM versions may cause stutter >> + * https://www.amd.com/en/support/kb/faq/pa-410 >> + * >> + * Fixes are available in two series of fTPM firmware: >> + * 6.x.y.z series: 6.0.18.6 + >> + * 3.x.y.z series: 3.57.y.5 + >> + */ >> +static bool tpm_amd_is_rng_defective(struct tpm_chip *chip) >> +{ >> + u32 val1, val2; >> + u64 version; >> + int ret; >> + >> + if (!(chip->flags & TPM_CHIP_FLAG_TPM2)) >> + return false; >> + >> + ret = tpm_request_locality(chip); >> + if (ret) >> + return false; >> + >> + ret = tpm2_get_tpm_pt(chip, TPM2_PT_MANUFACTURER, &val1, NULL); >> + if (ret) >> + goto release; >> + if (val1 != 0x414D4400U /* AMD */) { >> + ret = -ENODEV; >> + goto release; >> + } >> + ret = tpm2_get_tpm_pt(chip, TPM2_PT_FIRMWARE_VERSION_1, &val1, NULL); >> + if (ret) >> + goto release; >> + ret = tpm2_get_tpm_pt(chip, TPM2_PT_FIRMWARE_VERSION_2, &val2, NULL); >> + if (ret) >> + goto release; > > This goto is unnecessary. > >> + >> +release: >> + tpm_relinquish_locality(chip); >> + >> + if (ret) >> + return false; >> + >> + version = ((u64)val1 << 32) | val2; >> + if ((version >> 48) == 6) { >> + if (version >= 0x0006000000180006ULL) >> + return false; >> + } else if ((version >> 48) == 3) { >> + if (version >= 0x0003005700000005ULL) >> + return false; >> + } else >> + return false; > > checkpatch: > > CHECK: braces {} should be used on all arms of this statement > #200: FILE: drivers/char/tpm/tpm-chip.c:557: > + if ((version >> 48) == 6) { > [...] > + } else if ((version >> 48) == 3) { > [...] > + } else > [...]
It was requested by Jarko explicitly in v1 to do it this way.
https://lore.kernel.org/lkml/Y+%2F6G+UlTI7GpW6o@kernel.org/
> >> + >> + dev_warn(&chip->dev, >> + "AMD fTPM version 0x%llx causes system stutter; hwrng disabled\n", >> + version); >> + >> + return true; >> +} >> + >> static int tpm_hwrng_read(struct hwrng *rng, void *data, size_t max, bool wait) >> { >> struct tpm_chip *chip = container_of(rng, struct tpm_chip, hwrng); >> @@ -521,7 +579,8 @@ static int tpm_hwrng_read(struct hwrng *rng, void *data, size_t max, bool wait) >> >> static int tpm_add_hwrng(struct tpm_chip *chip) >> { >> - if (!IS_ENABLED(CONFIG_HW_RANDOM_TPM) || tpm_is_firmware_upgrade(chip)) >> + if (!IS_ENABLED(CONFIG_HW_RANDOM_TPM) || tpm_is_firmware_upgrade(chip) || >> + tpm_amd_is_rng_defective(chip)) >> return 0; >> >> snprintf(chip->hwrng_name, sizeof(chip->hwrng_name), >> diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h >> index 24ee4e1cc452..830014a26609 100644 >> --- a/drivers/char/tpm/tpm.h >> +++ b/drivers/char/tpm/tpm.h >> @@ -150,6 +150,79 @@ enum tpm_sub_capabilities { >> TPM_CAP_PROP_TIS_DURATION = 0x120, >> }; >> >> +enum tpm2_pt_props { >> + TPM2_PT_NONE = 0x00000000, >> + TPM2_PT_GROUP = 0x00000100, >> + TPM2_PT_FIXED = TPM2_PT_GROUP * 1, >> + TPM2_PT_FAMILY_INDICATOR = TPM2_PT_FIXED + 0, >> + TPM2_PT_LEVEL = TPM2_PT_FIXED + 1, >> + TPM2_PT_REVISION = TPM2_PT_FIXED + 2, >> + TPM2_PT_DAY_OF_YEAR = TPM2_PT_FIXED + 3, >> + TPM2_PT_YEAR = TPM2_PT_FIXED + 4, >> + TPM2_PT_MANUFACTURER = TPM2_PT_FIXED + 5, >> + TPM2_PT_VENDOR_STRING_1 = TPM2_PT_FIXED + 6, >> + TPM2_PT_VENDOR_STRING_2 = TPM2_PT_FIXED + 7, >> + TPM2_PT_VENDOR_STRING_3 = TPM2_PT_FIXED + 8, >> + TPM2_PT_VENDOR_STRING_4 = TPM2_PT_FIXED + 9, >> + TPM2_PT_VENDOR_TPM_TYPE = TPM2_PT_FIXED + 10, >> + TPM2_PT_FIRMWARE_VERSION_1 = TPM2_PT_FIXED + 11, >> + TPM2_PT_FIRMWARE_VERSION_2 = TPM2_PT_FIXED + 12, >> + TPM2_PT_INPUT_BUFFER = TPM2_PT_FIXED + 13, >> + TPM2_PT_HR_TRANSIENT_MIN = TPM2_PT_FIXED + 14, >> + TPM2_PT_HR_PERSISTENT_MIN = TPM2_PT_FIXED + 15, >> + TPM2_PT_HR_LOADED_MIN = TPM2_PT_FIXED + 16, >> + TPM2_PT_ACTIVE_SESSIONS_MAX = TPM2_PT_FIXED + 17, >> + TPM2_PT_PCR_COUNT = TPM2_PT_FIXED + 18, >> + TPM2_PT_PCR_SELECT_MIN = TPM2_PT_FIXED + 19, >> + TPM2_PT_CONTEXT_GAP_MAX = TPM2_PT_FIXED + 20, >> + TPM2_PT_NV_COUNTERS_MAX = TPM2_PT_FIXED + 22, >> + TPM2_PT_NV_INDEX_MAX = TPM2_PT_FIXED + 23, >> + TPM2_PT_MEMORY = TPM2_PT_FIXED + 24, >> + TPM2_PT_CLOCK_UPDATE = TPM2_PT_FIXED + 25, >> + TPM2_PT_CONTEXT_HASH = TPM2_PT_FIXED + 26, >> + TPM2_PT_CONTEXT_SYM = TPM2_PT_FIXED + 27, >> + TPM2_PT_CONTEXT_SYM_SIZE = TPM2_PT_FIXED + 28, >> + TPM2_PT_ORDERLY_COUNT = TPM2_PT_FIXED + 29, >> + TPM2_PT_MAX_COMMAND_SIZE = TPM2_PT_FIXED + 30, >> + TPM2_PT_MAX_RESPONSE_SIZE = TPM2_PT_FIXED + 31, >> + TPM2_PT_MAX_DIGEST = TPM2_PT_FIXED + 32, >> + TPM2_PT_MAX_OBJECT_CONTEXT = TPM2_PT_FIXED + 33, >> + TPM2_PT_MAX_SESSION_CONTEXT = TPM2_PT_FIXED + 34, >> + TPM2_PT_PS_FAMILY_INDICATOR = TPM2_PT_FIXED + 35, >> + TPM2_PT_PS_LEVEL = TPM2_PT_FIXED + 36, >> + TPM2_PT_PS_REVISION = TPM2_PT_FIXED + 37, >> + TPM2_PT_PS_DAY_OF_YEAR = TPM2_PT_FIXED + 38, >> + TPM2_PT_PS_YEAR = TPM2_PT_FIXED + 39, >> + TPM2_PT_SPLIT_MAX = TPM2_PT_FIXED + 40, >> + TPM2_PT_TOTAL_COMMANDS = TPM2_PT_FIXED + 41, >> + TPM2_PT_LIBRARY_COMMANDS = TPM2_PT_FIXED + 42, >> + TPM2_PT_VENDOR_COMMANDS = TPM2_PT_FIXED + 43, >> + TPM2_PT_NV_BUFFER_MAX = TPM2_PT_FIXED + 44, >> + TPM2_PT_MODES = TPM2_PT_FIXED + 45, >> + TPM2_PT_MAX_CAP_BUFFER = TPM2_PT_FIXED + 46, >> + TPM2_PT_VAR = TPM2_PT_GROUP * 2, >> + TPM2_PT_PERMANENT = TPM2_PT_VAR + 0, >> + TPM2_PT_STARTUP_CLEAR = TPM2_PT_VAR + 1, >> + TPM2_PT_HR_NV_INDEX = TPM2_PT_VAR + 2, >> + TPM2_PT_HR_LOADED = TPM2_PT_VAR + 3, >> + TPM2_PT_HR_LOADED_AVAIL = TPM2_PT_VAR + 4, >> + TPM2_PT_HR_ACTIVE = TPM2_PT_VAR + 5, >> + TPM2_PT_HR_ACTIVE_AVAIL = TPM2_PT_VAR + 6, >> + TPM2_PT_HR_TRANSIENT_AVAIL = TPM2_PT_VAR + 7, >> + TPM2_PT_HR_PERSISTENT = TPM2_PT_VAR + 8, >> + TPM2_PT_HR_PERSISTENT_AVAIL = TPM2_PT_VAR + 9, >> + TPM2_PT_NV_COUNTERS = TPM2_PT_VAR + 10, >> + TPM2_PT_NV_COUNTERS_AVAIL = TPM2_PT_VAR + 11, >> + TPM2_PT_ALGORITHM_SET = TPM2_PT_VAR + 12, >> + TPM2_PT_LOADED_CURVES = TPM2_PT_VAR + 13, >> + TPM2_PT_LOCKOUT_COUNTER = TPM2_PT_VAR + 14, >> + TPM2_PT_MAX_AUTH_FAIL = TPM2_PT_VAR + 15, >> + TPM2_PT_LOCKOUT_INTERVAL = TPM2_PT_VAR + 16, >> + TPM2_PT_LOCKOUT_RECOVERY = TPM2_PT_VAR + 17, >> + TPM2_PT_NV_WRITE_RECOVERY = TPM2_PT_VAR + 18, >> + TPM2_PT_AUDIT_COUNTER_0 = TPM2_PT_VAR + 19, >> + TPM2_PT_AUDIT_COUNTER_1 = TPM2_PT_VAR + 20, >> +}; >> >> /* 128 bytes is an arbitrary cap. This could be as large as TPM_BUFSIZE - 18 >> * bytes, but 128 is still a relatively large number of random bytes and >> -- >> 2.34.1 >>
| |