tablet/grub
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

tpm2_key_protector: Implement NV index

Browse Source 
Currently with the TPM2 protector, only SRK mode is supported and
NV index support is just a stub. Implement the NV index option.

Note: This only extends support on the unseal path. grub-protect
has not been updated. tpm2-tools can be used to insert a key into
the NV index.

An example of inserting a key using tpm2-tools:

  # Get random key.
  tpm2_getrandom 32 > key.dat

  # Create primary object.
  tpm2_createprimary -C o -g sha256 -G ecc -c primary.ctx

  # Create policy object. `pcrs.dat` contains the PCR values to seal against.
  tpm2_startauthsession -S session.dat
  tpm2_policypcr -S session.dat -l sha256:7,11 -f pcrs.dat -L policy.dat
  tpm2_flushcontext session.dat

  # Seal key into TPM.
  cat key.dat | tpm2_create -C primary.ctx -u key.pub -r key.priv -L policy.dat -i-
  tpm2_load -C primary.ctx -u key.pub -r key.priv -n sealing.name -c sealing.ctx
  tpm2_evictcontrol -C o -c sealing.ctx 0x81000000

Then to unseal the key in GRUB, add this to grub.cfg:

  tpm2_key_protector_init --mode=nv --nvindex=0x81000000 --pcrs=7,11
  cryptomount -u <UUID> --protector tpm2

Signed-off-by: Patrick Colp <patrick.colp@oracle.com>
Signed-off-by: Gary Lin <glin@suse.com>
Reviewed-by: Stefan Berger <stefanb@linux.ibm.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
Tested-by: Stefan Berger <stefanb@linux.ibm.com>
This commit is contained in:
Patrick Colp 2024-11-15 15:34:55 +08:00 committed by Daniel Kiper
parent 550ada7d67
commit fba3a474e0
1 changed files with 19 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

23
grub-core/commands/tpm2_key_protector/module.c
View File

@ -973,11 +973,26 @@ tpm2_protector_srk_recover (const tpm2_protector_context_t *ctx,
}
static grub_err_t
tpm2_protector_nv_recover (const tpm2_protector_context_t *ctx __attribute__ ((unused)),
grub_uint8_t **key __attribute__ ((unused)),
grub_size_t *key_size __attribute__ ((unused)))
tpm2_protector_nv_recover (const tpm2_protector_context_t *ctx,
grub_uint8_t **key, grub_size_t *key_size)
{
return grub_error (GRUB_ERR_NOT_IMPLEMENTED_YET, "NV Index mode is not implemented yet");
TPM_HANDLE_t sealed_handle = ctx->nv;
tpm2key_policy_t policy_seq = NULL;
grub_err_t err;
/* Create a basic policy sequence based on the given PCR selection */
err = tpm2_protector_simple_policy_seq (ctx, &policy_seq);
if (err != GRUB_ERR_NONE)
goto exit;
err = tpm2_protector_unseal (policy_seq, sealed_handle, key, key_size);
exit:
grub_tpm2_flushcontext (sealed_handle);
grub_tpm2key_free_policy_seq (policy_seq);
return err;
}
static grub_err_t