From: Patrick Colp <patrick.colp@oracle.com>
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. grub2_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>
---
grub-core/tpm2/module.c | 25 ++++++++++++++++++++-----
1 file changed, 20 insertions(+), 5 deletions(-)
diff --git a/grub-core/tpm2/module.c b/grub-core/tpm2/module.c
index 0ed8f2682..b4d588b0c 100644
--- a/grub-core/tpm2/module.c
+++ b/grub-core/tpm2/module.c
@@ -1022,12 +1022,27 @@ static grub_err_t
grub_tpm2_protector_nv_recover (const struct grub_tpm2_protector_context *ctx,
grub_uint8_t **key, grub_size_t *key_size)
{
- (void)ctx;
- (void)key;
- (void)key_size;
+ TPM_HANDLE 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 = grub_tpm2_protector_simple_policy_seq (ctx, &policy_seq);
+ if (err != GRUB_ERR_NONE)
+ goto exit;
+
+ err = grub_tpm2_protector_unseal (policy_seq, sealed_handle, key, key_size);
+
+ /* Pop error messages on success */
+ if (err == GRUB_ERR_NONE)
+ while (grub_error_pop ());
+
+exit:
+ TPM2_FlushContext (sealed_handle);
- return grub_error (GRUB_ERR_NOT_IMPLEMENTED_YET,
- N_("NV Index mode is not implemented yet"));
+ grub_tpm2key_free_policy_seq (policy_seq);
+
+ return err;
}
static grub_err_t