Hello Jarkko, On 12/07/2017 02:32 AM, Jarkko Sakkinen wrote: > On Mon, Nov 27, 2017 at 12:30:12AM +0100, Javier Martinez Canillas wrote: >> According to the TPM Library Specification, a TPM device must do a command >> header validation before processing and return a TPM_RC_COMMAND_CODE code >> if the command is not implemented. >> >> So user-space will expect to handle that response as an error. But if the >> in-kernel resource manager is used (/dev/tpmrm?), an -EINVAL errno code is >> returned instead if the command isn't implemented. This confuses userspace >> since it doesn't expect that error value. >> >> This also isn't consistent with the behavior when not using TPM spaces and >> accessing the TPM directly (/dev/tpm?). In this case, the command is sent >> to the TPM even when not implemented and the TPM responds with an error. >> >> Instead of returning an -EINVAL errno code when the tpm_validate_command() >> function fails, synthesize a TPM command response so user-space can get a >> TPM_RC_COMMAND_CODE as expected when a chip doesn't implement the command. >> >> The TPM only sets 12 of the 32 bits in the TPM_RC response, so the TSS and >> TAB specifications define that higher layers in the stack should use some >> of the unused 20 bits to specify from which level of the stack the error >> is coming from. >> >> Since the TPM_RC_COMMAND_CODE response code is sent by the kernel resource >> manager, set the error level to the TAB/RM layer so user-space is aware of >> this. >> >> Suggested-by: Jason Gunthorpe <jgg@xxxxxxxx> >> Signed-off-by: Javier Martinez Canillas <javierm@xxxxxxxxxx> >> >> --- >> >> Changes since RFCv2: >> - Set the error level to the TAB/RM layer so user-space is aware that the error >> is not coming from the TPM (suggested by Philip Tricca and Jarkko Sakkinen). >> >> Changes since RFCv1: >> - Don't pass not validated commands to the TPM, instead return a synthesized >> response with the correct TPM return code (suggested by Jason Gunthorpe). >> >> And example of user-space getting confused by the TPM chardev returning -EINVAL >> when sending a not supported TPM command can be seen in this tpm2-tools issue: >> >> https://github.com/intel/tpm2-tools/issues/621 >> >> Best regards, >> Javier >> >> drivers/char/tpm/tpm-interface.c | 28 ++++++++++++++++++++-------- >> drivers/char/tpm/tpm.h | 8 ++++++++ >> 2 files changed, 28 insertions(+), 8 deletions(-) >> >> diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c >> index ebe0a1d36d8c..9391811c5f83 100644 >> --- a/drivers/char/tpm/tpm-interface.c >> +++ b/drivers/char/tpm/tpm-interface.c >> @@ -328,7 +328,7 @@ unsigned long tpm_calc_ordinal_duration(struct tpm_chip *chip, >> } >> EXPORT_SYMBOL_GPL(tpm_calc_ordinal_duration); >> >> -static bool tpm_validate_command(struct tpm_chip *chip, >> +static int tpm_validate_command(struct tpm_chip *chip, >> struct tpm_space *space, >> const u8 *cmd, >> size_t len) >> @@ -340,10 +340,10 @@ static bool tpm_validate_command(struct tpm_chip *chip, >> unsigned int nr_handles; >> >> if (len < TPM_HEADER_SIZE) >> - return false; >> + return -EINVAL; >> >> if (!space) >> - return true; >> + return 0; >> >> if (chip->flags & TPM_CHIP_FLAG_TPM2 && chip->nr_commands) { >> cc = be32_to_cpu(header->ordinal); >> @@ -352,7 +352,7 @@ static bool tpm_validate_command(struct tpm_chip *chip, >> if (i < 0) { >> dev_dbg(&chip->dev, "0x%04X is an invalid command\n", >> cc); >> - return false; >> + return -EOPNOTSUPP; >> } >> >> attrs = chip->cc_attrs_tbl[i]; >> @@ -362,11 +362,11 @@ static bool tpm_validate_command(struct tpm_chip *chip, >> goto err_len; >> } >> >> - return true; >> + return 0; >> err_len: >> dev_dbg(&chip->dev, >> "%s: insufficient command length %zu", __func__, len); >> - return false; >> + return -EINVAL; >> } >> >> /** >> @@ -391,8 +391,20 @@ ssize_t tpm_transmit(struct tpm_chip *chip, struct tpm_space *space, >> unsigned long stop; >> bool need_locality; >> >> - if (!tpm_validate_command(chip, space, buf, bufsiz)) >> - return -EINVAL; >> + rc = tpm_validate_command(chip, space, buf, bufsiz); >> + if (rc == -EINVAL) >> + return rc; >> + /* >> + * If the command is not implemented by the TPM, synthesize a >> + * response with a TPM2_RC_COMMAND_CODE return for user-space. >> + */ >> + if (rc == -EOPNOTSUPP) { >> + header->length = cpu_to_be32(sizeof(*header)); >> + header->tag = cpu_to_be16(TPM2_ST_NO_SESSIONS); >> + header->return_code = cpu_to_be32(TPM2_RC_COMMAND_CODE | >> + TPM2_RESMGRTPM_ERROR_LEVEL); >> + return bufsiz; >> + } >> >> if (bufsiz > TPM_BUFSIZE) >> bufsiz = TPM_BUFSIZE; >> diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h >> index c1866cc02e30..b3f9108d3d1f 100644 >> --- a/drivers/char/tpm/tpm.h >> +++ b/drivers/char/tpm/tpm.h >> @@ -94,12 +94,20 @@ enum tpm2_structures { >> TPM2_ST_SESSIONS = 0x8002, >> }; >> >> +/* Indicates from what level of the software stack the error comes from */ >> +#define TPM2_RC_LEVEL_SHIFT 16 >> + >> +#define TPM2_RESMGRTPM_ERROR_LEVEL (11 << TPM2_RC_LEVEL_SHIFT) >> +#define TPM2_RESMGR_ERROR_LEVEL (12 << TPM2_RC_LEVEL_SHIFT) >> +#define TPM2_DRIVER_ERROR_LEVEL (13 << TPM2_RC_LEVEL_SHIFT) >> + >> enum tpm2_return_codes { >> TPM2_RC_SUCCESS = 0x0000, >> TPM2_RC_HASH = 0x0083, /* RC_FMT1 */ >> TPM2_RC_HANDLE = 0x008B, >> TPM2_RC_INITIALIZE = 0x0100, /* RC_VER1 */ >> TPM2_RC_DISABLED = 0x0120, >> + TPM2_RC_COMMAND_CODE = 0x0143, >> TPM2_RC_TESTING = 0x090A, /* RC_WARN */ >> TPM2_RC_REFERENCE_H0 = 0x0910, >> }; >> -- >> 2.14.3 >> > > Please use next time --subject-prefix="PATCH v3". > I did. But you are answering to my v1 patch. The v3 can be found here with the following subject "[PATCH v3] tpm: return a TPM_RC_COMMAND_CODE response if command is not implemented" https://patchwork.kernel.org/patch/10084305/ Probably you got confused because I posted 2 RFCs before posting a proper PATCH and then PATCHv3 and v3. > Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@xxxxxxxxxxxxxxx> > Thanks! As mentioned this is v1, but I guess it also applies to v3 since the only differences are the removal of the unused defines and the naming change we discussed. > /Jarkko > Best regards, -- Javier Martinez Canillas Software Engineer - Desktop Hardware Enablement Red Hat
