Streamline TPM2 HMAC sessions

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