[PATCH v9 00/11] Streamline TPM2 HMAC sessions

Jarkko Sakkinen
2026-01-25T19:25:38Z

This patch set contains accumulated patches, which gradually improve
TPM2 HMAC session management and TPM driver memory management.

RNG test
========

I run this test both TPM1 and TPM2 chips using QEMU and swtpm:

#!/bin/sh

ctrl_c() {
set +e
echo 0 > tracing_on
echo nop > current_tracer
echo BYE
exit
}

trap ctrl_c EXIT INT
mount -t tracefs none /sys/kernel/tracing

set -e
cd /sys/kernel/tracing
echo function > current_tracer
echo p:tpm_get_random tpm_get_random > kprobe_events
echo tpm_get_random > set_ftrace_filter
echo 1 > tracing_on
cat /dev/hwrng > /dev/null &
echo > trace
cat trace_pipe &
sleep 10

Change Log
==========

v9:
- Simplified hwrng patches.
- Minor tweaks.
v8:
- Patch was a bit out-of-sync after piling new stuff. Now it is somewhat
sane: RNG patches first, then tpm2-sessions and finally managed
tpm_buf allocations.
- I added inline comment on explaining why unconditional sha256_update()
call is safe to do when managing only single authorization handle.
v7:
- Updated cover letter to match better the current state of the patch
set.
v6:
- OK, so I decided to send one more update with managed allocations
moved to the tail so that it does not block reviewing more trivial
patches.
- Trimmed some of the patches and improved commit messages.
v5:
- I decided to add the managed allocation patch to this and take it from
the master branch for the time being, as it needs more eyes despite
having already one reviewed-by tag (especially tested-by tags).

Jarkko Sakkinen (11):
KEYS: trusted: Use get_random-fallback for TPM
KEYS: trusted: Use get_random_bytes_wait() instead of tpm_get_random()
tpm: Change tpm_get_random() opportunistic
tpm2-sessions: Define TPM2_NAME_MAX_SIZE
KEYS: trusted: Open code tpm2_buf_append()
KEYS: trusted: Remove dead branch from tpm2_unseal_cmd
KEYS: trusted: Re-orchestrate tpm2_read_public() calls
tpm2-sessions: Remove the support for more than one authorization
tpm-buf: Remove tpm_buf_append_handle
tpm-buf: Merge TPM_BUF_BOUNDARY_ERROR and TPM_BUF_OVERFLOW
tpm-buf: Implement managed allocations

drivers/char/tpm/tpm-buf.c | 156 ++++-----
drivers/char/tpm/tpm-interface.c | 20 +-
drivers/char/tpm/tpm-sysfs.c | 23 +-
drivers/char/tpm/tpm.h | 1 -
drivers/char/tpm/tpm1-cmd.c | 201 +++++------
drivers/char/tpm/tpm2-cmd.c | 386 ++++++++++------------
drivers/char/tpm/tpm2-sessions.c | 281 ++++++----------
drivers/char/tpm/tpm2-space.c | 44 +--
drivers/char/tpm/tpm_vtpm_proxy.c | 30 +-
include/linux/tpm.h | 77 +++--
security/keys/trusted-keys/trusted_tpm1.c | 70 ++--
security/keys/trusted-keys/trusted_tpm2.c | 327 +++++++++---------
12 files changed, 735 insertions(+), 881 deletions(-)

--
2.52.0