tree 50455728a1f7f662e1a7c69d4434d014213e108e
parent ca44b077a889ea7ddb6d5de712ac6dd0d6a3d67e
author Kees Cook <keescook@chromium.org> 1354067197 -0800
committer Gerrit <chrome-bot@google.com> 1354167349 -0800

Tlcl: allow OS failures to bubble up to caller

If there were any errors communicating with the TPM at the OS layer
(open, read, write failures), the library would immediately exit, not
allowing the caller to make any decisions about how to handle it. This
introduces a way to initialize the library so that errors will get passed
back up to the caller instead of unceremoniously exiting.

Setting the environment variable "TPM_NO_EXIT=1" enables the feature. To
avoid needing to implement supporting functions in all backends, the
feature is currently limited to just the Tlcl stub implementation.

In the case of mount-encrypted, it can now survive the kernel returning
read/write failures. In the past it had only worked around having open
fail, but that has now been replaced with more sensible logic instead of
the environment variable trickiness.

BUG=chrome-os-partner:15960
TEST=daisy built with an always-failing kernel driver, u-boot builds too
BRANCH=None

Change-Id: Ic7b217017537980f9c239d678067398613045676
Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-on: https://gerrit.chromium.org/gerrit/38791
Reviewed-by: Luigi Semenzato <semenzato@chromium.org>