Re: [PATCH] tpm: fix a race condition tpm2_unseal_trusted()
From: Jason Gunthorpe <hidden>
Date: 2016-08-25 18:33:35
Also in:
lkml
On Tue, Aug 23, 2016 at 08:57:22PM -0400, Jarkko Sakkinen wrote:
+ if (flags & TPM_TRANSMIT_LOCK) + mutex_lock(&chip->tpm_mutex);
I think I would invert this. UNLOCKED is the exceptional case, so I'd make the 0 flags lock. If we see UNLOCKED in the caller then we know to audit for locking, 0 is much less obvious.
quoted hunk ↗ jump to hunk
@@ -576,7 +576,7 @@ static int tpm2_load(struct tpm_chip *chip, goto out; } - rc = tpm_transmit_cmd(chip, buf.data, PAGE_SIZE, "loading blob"); + rc = __tpm_transmit_cmd(chip, buf.data, PAGE_SIZE, "loading blob", 0);
All these points should accept a flags too and the caller should pass in the TPM_TRASNMIT_UNLOCKED if it needs it..
+ mutex_lock(&chip->tpm_mutex); rc = tpm2_load(chip, payload, options, &blob_handle); if (rc)
So when we read here we see the pattern:
+ mutex_lock(&chip->tpm_mutex); rc = tpm2_load(chip, payload, options, &blob_handle, TPM_TRASNMIT_UNLOCKED);
Which is much easier to audit.. Jason