[SLOF] [PATCH 0/3] vTPM: Measure the bootloader

Stefan Berger stefanb at linux.vnet.ibm.com
Wed May 13 01:44:49 AEST 2020

This series of patches adds support for measuring the booloader read from
a GPT partition. Since the boot loader is read into a buffer much bigger
(0x700000 bytes) than the original file, we need a way to determine the
original file size of the boot loader so that we measure only those
bytes from the buffer that are also found in the file. The file is
assumed to be an ELF file. We do this by extending libelf with a function
that allows us to determine the ELF file's original file size by walking
the ELF headers and looking for the farthest offset. In the normal case
this will result in the same hash calculated as if one does for example
'sha256sum grub'. However, it could lead to a different measurement if
the user intentionately appended bytes to the file, which are not
referenced by any ELF section. We cannot solve this case.


  - addressed nits

  - Followed Alexey's comments
  - Renamed new function suffix from '_file' to '_buffer' to be more

Stefan Berger (3):
  elf: Implement elf_get_file_size to determine size of an ELF image
  tcgbios: Implement tpm_hash_log_extend_event_buffer
  tcgbios: Measure the bootloader file read from disk

 include/helpers.h              |  2 +
 include/libelf.h               | 14 +++++++
 lib/libelf/elf.c               | 26 +++++++++++++
 lib/libelf/elf32.c             | 69 ++++++++++++++++++++++++++++++++++
 lib/libelf/elf64.c             | 57 ++++++++++++++++++++++++++++
 lib/libtpm/tcgbios.c           | 44 ++++++++++++++++++++++
 lib/libtpm/tcgbios.h           |  5 +++
 lib/libtpm/tpm.code            | 19 ++++++++++
 lib/libtpm/tpm.in              |  1 +
 slof/fs/packages/disk-label.fs | 19 +++++++++-
 10 files changed, 255 insertions(+), 1 deletion(-)


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