On Tue, Sep 27, 2022 at 09:49:12AM -0700, Evan Green wrote: > From: Matthew Garrett <matthewgarrett@xxxxxxxxxx> > > Add an internal command for resetting a PCR. This will be used by the > encrypted hibernation code to set PCR23 to a known value. The > hibernation code will seal the hibernation key with a policy specifying > PCR23 be set to this known value as a mechanism to ensure that the > hibernation key is genuine. But to do this repeatedly, resetting the PCR > is necessary as well. > > Link: https://lore.kernel.org/lkml/20210220013255.1083202-2-matthewgarrett@xxxxxxxxxx/ > Signed-off-by: Matthew Garrett <mjg59@xxxxxxxxxx> > Signed-off-by: Evan Green <evgreen@xxxxxxxxxxxx> > --- > > Changes in v3: > - Unify tpm1/2_pcr_reset prototypes (Jarkko) > - Wait no, remove the TPM1 stuff altogether (Jarkko) > - Remove extra From tag and blank in commit msg (Jarkko). > > drivers/char/tpm/tpm-interface.c | 25 ++++++++++++++++++++++ > drivers/char/tpm/tpm.h | 1 + > drivers/char/tpm/tpm2-cmd.c | 36 ++++++++++++++++++++++++++++++++ > include/linux/tpm.h | 7 +++++++ > 4 files changed, 69 insertions(+) > > diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c > index 1621ce8187052c..2ac9079860b1e0 100644 > --- a/drivers/char/tpm/tpm-interface.c > +++ b/drivers/char/tpm/tpm-interface.c > @@ -342,6 +342,31 @@ int tpm_pcr_extend(struct tpm_chip *chip, u32 pcr_idx, > } > EXPORT_SYMBOL_GPL(tpm_pcr_extend); > > +/** > + * tpm_pcr_reset - reset the specified PCR > + * @chip: a &struct tpm_chip instance, %NULL for the default chip > + * @pcr_idx: the PCR to be reset > + * > + * Return: same as with tpm_transmit_cmd(), or ENOTTY for TPM1 devices. > + */ > +int tpm_pcr_reset(struct tpm_chip *chip, u32 pcr_idx) > +{ > + int rc; > + > + chip = tpm_find_get_ops(chip); > + if (!chip) > + return -ENODEV; > + > + if (chip->flags & TPM_CHIP_FLAG_TPM2) > + rc = tpm2_pcr_reset(chip, pcr_idx); > + else > + rc = -ENOTTY; > + > + tpm_put_ops(chip); > + return rc; > +} > +EXPORT_SYMBOL_GPL(tpm_pcr_reset); Please rename this as tpm2_pcr_reset() and open code the contents of the current tpm2_pcd_reset() into it, as this layering is now obsolete. > + > /** > * tpm_send - send a TPM command > * @chip: a &struct tpm_chip instance, %NULL for the default chip > diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h > index 24ee4e1cc452a0..34e20b3192f833 100644 > --- a/drivers/char/tpm/tpm.h > +++ b/drivers/char/tpm/tpm.h > @@ -217,6 +217,7 @@ int tpm2_pcr_read(struct tpm_chip *chip, u32 pcr_idx, > struct tpm_digest *digest, u16 *digest_size_ptr); > int tpm2_pcr_extend(struct tpm_chip *chip, u32 pcr_idx, > struct tpm_digest *digests); > +int tpm2_pcr_reset(struct tpm_chip *chip, u32 pcr_idx); > int tpm2_get_random(struct tpm_chip *chip, u8 *dest, size_t max); > ssize_t tpm2_get_tpm_pt(struct tpm_chip *chip, u32 property_id, > u32 *value, const char *desc); > diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c > index 65d03867e114c5..69126a6770386e 100644 > --- a/drivers/char/tpm/tpm2-cmd.c > +++ b/drivers/char/tpm/tpm2-cmd.c > @@ -269,6 +269,42 @@ int tpm2_pcr_extend(struct tpm_chip *chip, u32 pcr_idx, > return rc; > } > > +/** > + * tpm2_pcr_reset() - reset a PCR > + * Remove empty line and "Reset a PCR" with a capital. There might be random conventions in this but I'm now referring to just what this says: https://www.kernel.org/doc/html/v5.19/doc-guide/kernel-doc.html I.e. better to align with documentation for this and future patches. > + * @chip: TPM chip to use. > + * @pcr_idx: index of the PCR. > + * > + * Return: Same as with tpm_transmit_cmd. > + */ > +int tpm2_pcr_reset(struct tpm_chip *chip, u32 pcr_idx) > +{ > + struct tpm_buf buf; > + struct tpm2_null_auth_area auth_area; > + int rc; > + > + rc = tpm_buf_init(&buf, TPM2_ST_SESSIONS, TPM2_CC_PCR_RESET); > + if (rc) > + return rc; > + > + tpm_buf_append_u32(&buf, pcr_idx); > + > + auth_area.handle = cpu_to_be32(TPM2_RS_PW); > + auth_area.nonce_size = 0; > + auth_area.attributes = 0; > + auth_area.auth_size = 0; > + > + tpm_buf_append_u32(&buf, sizeof(struct tpm2_null_auth_area)); > + tpm_buf_append(&buf, (const unsigned char *)&auth_area, > + sizeof(auth_area)); > + > + rc = tpm_transmit_cmd(chip, &buf, 0, "attempting to reset a PCR"); > + > + tpm_buf_destroy(&buf); > + > + return rc; > +} > + > struct tpm2_get_random_out { > __be16 size; > u8 buffer[TPM_MAX_RNG_DATA]; > diff --git a/include/linux/tpm.h b/include/linux/tpm.h > index dfeb25a0362dee..8320cbac6f4009 100644 > --- a/include/linux/tpm.h > +++ b/include/linux/tpm.h > @@ -219,6 +219,7 @@ enum tpm2_command_codes { > TPM2_CC_HIERARCHY_CONTROL = 0x0121, > TPM2_CC_HIERARCHY_CHANGE_AUTH = 0x0129, > TPM2_CC_CREATE_PRIMARY = 0x0131, > + TPM2_CC_PCR_RESET = 0x013D, > TPM2_CC_SEQUENCE_COMPLETE = 0x013E, > TPM2_CC_SELF_TEST = 0x0143, > TPM2_CC_STARTUP = 0x0144, > @@ -423,6 +424,7 @@ extern ssize_t tpm_transmit_cmd(struct tpm_chip *chip, struct tpm_buf *buf, > size_t min_rsp_body_length, const char *desc); > extern int tpm_pcr_read(struct tpm_chip *chip, u32 pcr_idx, > struct tpm_digest *digest); > +extern int tpm_pcr_reset(struct tpm_chip *chip, u32 pcr_idx); > extern int tpm_pcr_extend(struct tpm_chip *chip, u32 pcr_idx, > struct tpm_digest *digests); > extern int tpm_send(struct tpm_chip *chip, void *cmd, size_t buflen); > @@ -440,6 +442,11 @@ static inline int tpm_pcr_read(struct tpm_chip *chip, int pcr_idx, > return -ENODEV; > } > > +static inline int tpm_pcr_reset(struct tpm_chip *chip, int pcr_idx) > +{ > + return -ENODEV; > +} > + > static inline int tpm_pcr_extend(struct tpm_chip *chip, u32 pcr_idx, > struct tpm_digest *digests) > { > -- > 2.31.0 > BR, Jarkko
