NAK. Not sure on the logic that decided this was applicable for 5.4, but it's obviously not even been compile tested:
noodles@sevai:~/checkouts/linux$ git checkout v5.4.291 Updating files: 100% (13517/13517), done. Previous HEAD position was 219d54332a09 Linux 5.4 HEAD is now at 52bcf31d8e3d Linux 5.4.291 noodles@sevai:~/checkouts/linux$ git grep tpm2_end_auth_session noodles@sevai:~/checkouts/linux$
The auth session bits were introduced in 699e3efd6c645 (tpm: Add HMAC session start and end functions), which landed in 6.10.
On Thu, Apr 03, 2025 at 03:20:50PM -0400, Sasha Levin wrote:
From: Jonathan McDowell noodles@meta.com
[ Upstream commit 1dbf74e00a5f882b04b398399b6def65cd51ef21 ]
Lazy flushing of TPM auth sessions can interact badly with IMA + kexec, resulting in loaded session handles being leaked across the kexec and not cleaned up. Fix by ensuring any active auth session is ended before the TPM is told about the shutdown, matching what is done when suspending.
Before:
root@debian-qemu-efi:~# tpm2_getcap handles-loaded-session root@debian-qemu-efi:~# tpm2_getcap handles-saved-session root@debian-qemu-efi:~# kexec --load --kexec-file-syscall … root@debian-qemu-efi:~# systemctl kexec … root@debian-qemu-efi:~# tpm2_getcap handles-loaded-session
- 0x2000000
root@debian-qemu-efi:~# tpm2_getcap handles-saved-session root@debian-qemu-efi:~# (repeat kexec steps) root@debian-qemu-efi:~# tpm2_getcap handles-loaded-session
- 0x2000000
- 0x2000001
root@debian-qemu-efi:~# tpm2_getcap handles-saved-session root@debian-qemu-efi:~#
After:
root@debian-qemu-efi:~# tpm2_getcap handles-loaded-session root@debian-qemu-efi:~# tpm2_getcap handles-saved-session root@debian-qemu-efi:~# kexec --load --kexec-file-syscall … root@debian-qemu-efi:~# systemctl kexec … root@debian-qemu-efi:~# tpm2_getcap handles-loaded-session root@debian-qemu-efi:~# tpm2_getcap handles-saved-session root@debian-qemu-efi:~#
Signed-off-by: Jonathan McDowell noodles@meta.com Signed-off-by: Jarkko Sakkinen jarkko@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org
drivers/char/tpm/tpm-chip.c | 1 + 1 file changed, 1 insertion(+)
diff --git a/drivers/char/tpm/tpm-chip.c b/drivers/char/tpm/tpm-chip.c index 17fbd7f7a2954..b33e938d80e8a 100644 --- a/drivers/char/tpm/tpm-chip.c +++ b/drivers/char/tpm/tpm-chip.c @@ -290,6 +290,7 @@ static int tpm_class_shutdown(struct device *dev) down_write(&chip->ops_sem); if (chip->flags & TPM_CHIP_FLAG_TPM2) { if (!tpm_chip_start(chip)) {
tpm2_end_auth_session(chip); tpm2_shutdown(chip, TPM2_SU_CLEAR); tpm_chip_stop(chip);-- 2.39.5
J.