From: Javier Martinez Canillas javierm@redhat.com
[ Upstream commit 095531f891e627e408606f2da4008d3d53e6748a ]
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@ziepe.ca Signed-off-by: Javier Martinez Canillas javierm@redhat.com Reviewed-by: William Roberts william.c.roberts@intel.com Reviewed-by: Philip Tricca philip.b.tricca@intel.com Reviewed-by: Jarkko Sakkinen jarkko.sakkinen@linux.intel.com Tested-by: Jarkko Sakkinen jarkko.sakkinen@linux.intel.com Signed-off-by: Jarkko Sakkinen jarkko.sakkinen@linux.intel.com Signed-off-by: Sasha Levin alexander.levin@microsoft.com --- drivers/char/tpm/tpm-interface.c | 28 ++++++++++++++++++++-------- drivers/char/tpm/tpm.h | 5 +++++ 2 files changed, 25 insertions(+), 8 deletions(-)
diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c index 5294442505cb..0f1dc35e7078 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 | + TSS2_RESMGR_TPM_RC_LAYER); + return bufsiz; + }
if (bufsiz > TPM_BUFSIZE) bufsiz = TPM_BUFSIZE; diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h index 2d5466a72e40..0b5b499f726a 100644 --- a/drivers/char/tpm/tpm.h +++ b/drivers/char/tpm/tpm.h @@ -93,12 +93,17 @@ enum tpm2_structures { TPM2_ST_SESSIONS = 0x8002, };
+/* Indicates from what layer of the software stack the error comes from */ +#define TSS2_RC_LAYER_SHIFT 16 +#define TSS2_RESMGR_TPM_RC_LAYER (11 << TSS2_RC_LAYER_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, };