On Wed, 2024-11-13 at 02:24 +0200, Jarkko Sakkinen wrote: > The initial HMAC session feature added TPM bus encryption and/or integrity > protection to various in-kernel TPM operations. This can cause performance > bottlenecks with IMA, as it heavily utilizes PCR extend operations. > > In order to mitigate this performance issue, introduce a kernel > command-line parameter to the TPM driver for disabling the integrity > protection for PCR extend operations (i.e. TPM2_PCR_Extend). > > Cc: James Bottomley <[email protected]> > Link: > https://lore.kernel.org/linux-integrity/[email protected]/ > Fixes: 6519fea6fd37 ("tpm: add hmac checks to tpm2_pcr_extend()") > Co-developed-by: Roberto Sassu <[email protected]> > Signed-off-by: Roberto Sassu <[email protected]> > Co-developed-by: Mimi Zohar <[email protected]> > Signed-off-by: Mimi Zohar <[email protected]> > Signed-off-by: Jarkko Sakkinen <[email protected]>
The module_param variable documentation needs to be updated to reflect the actual module_param variable 'disable_pcr_integrity'. Otherwise, Tested-by: Mimi Zohar <[email protected]> > --- > v3: > - Please test this too ;-) I did quick testing only. > - Fixed the reported glitches and mistakes. > v2: > - Followed Mimi's suggestions. > --- > .../admin-guide/kernel-parameters.txt | 9 ++++ > drivers/char/tpm/tpm-buf.c | 20 ++++++++ > drivers/char/tpm/tpm2-cmd.c | 30 ++++++++--- > drivers/char/tpm/tpm2-sessions.c | 51 ++++++++++--------- > include/linux/tpm.h | 3 ++ > 5 files changed, 82 insertions(+), 31 deletions(-) > > diff --git a/Documentation/admin-guide/kernel-parameters.txt > b/Documentation/admin-guide/kernel-parameters.txt > index 1666576acc0e..7107ad322b2e 100644 > --- a/Documentation/admin-guide/kernel-parameters.txt > +++ b/Documentation/admin-guide/kernel-parameters.txt > @@ -6727,6 +6727,15 @@ > torture.verbose_sleep_duration= [KNL] > Duration of each verbose-printk() sleep in jiffies. > > + tpm.disable_pcr_integrity_protection= [HW,TPM] -> tpm.disable_pcr_integrity= > + Do not protect PCR registers from unintended physical > + access, or interposers in the bus by the means of > + having an integrity protected session wrapped around > + TPM2_PCR_Extend command. Consider this in a situation > + where TPM is heavily utilized by IMA, thus protection > + causing a major performance hit, and the space where > + machines are deployed is by other means guarded. > + > tpm_suspend_pcr=[HW,TPM] > Format: integer pcr id > Specify that at suspend time, the tpm driver > diff --git a/drivers/char/tpm/tpm-buf.c b/drivers/char/tpm/tpm-buf.c > index cad0048bcc3c..e49a19fea3bd 100644 > --- a/drivers/char/tpm/tpm-buf.c > +++ b/drivers/char/tpm/tpm-buf.c > @@ -146,6 +146,26 @@ void tpm_buf_append_u32(struct tpm_buf *buf, const u32 > value) > } > EXPORT_SYMBOL_GPL(tpm_buf_append_u32); > > +/** > + * tpm_buf_append_handle() - Add a handle > + * @chip: &tpm_chip instance > + * @buf: &tpm_buf instance > + * @handle: a TPM object handle > + * > + * Add a handle to the buffer, and increase the count tracking the number of > + * handles in the command buffer. Works only for command buffers. > + */ > +void tpm_buf_append_handle(struct tpm_chip *chip, struct tpm_buf *buf, u32 > handle) > +{ > + if (buf->flags & TPM_BUF_TPM2B) { > + dev_err(&chip->dev, "Invalid buffer type (TPM2B)\n"); > + return; > + } > + > + tpm_buf_append_u32(buf, handle); > + buf->handles++; > +} > + > /** > * tpm_buf_read() - Read from a TPM buffer > * @buf: &tpm_buf instance > diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c > index 1e856259219e..dfdcbd009720 100644 > --- a/drivers/char/tpm/tpm2-cmd.c > +++ b/drivers/char/tpm/tpm2-cmd.c > @@ -14,6 +14,10 @@ > #include "tpm.h" > #include <crypto/hash_info.h> > > +static bool disable_pcr_integrity; > +module_param(disable_pcr_integrity, bool, 0444); > +MODULE_PARM_DESC(disable_pcr_integrity, "Disable integrity protection of > TPM2_PCR_Extend"); 'disable_pcr_integrity' doesn't match the documentation. > + > static struct tpm2_hash tpm2_hash_map[] = { > {HASH_ALGO_SHA1, TPM_ALG_SHA1}, > {HASH_ALGO_SHA256, TPM_ALG_SHA256}, > @@ -232,18 +236,26 @@ int tpm2_pcr_extend(struct tpm_chip *chip, u32 pcr_idx, thanks, Mimi
