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grub2/0006-tpm2_key_protector-Support-NV-index-handles.patch

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From cd9cb944d973da6a031d06183cc6da974beb4bae Mon Sep 17 00:00:00 2001
From: Gary Lin <glin@suse.com>
Date: Mon, 7 Apr 2025 16:29:20 +0800
Subject: [PATCH 6/7] tpm2_key_protector: Support NV index handles
Previously, NV index mode only supported persistent handles which are
only for TPM objects.
On the other hand, the "NV index" handle allows the user-defined data,
so it can be an alternative to the key file and support TPM 2.0 Key
File format immediately.
The following tpm2-tools commands store the given key file, sealed.tpm,
in either TPM 2.0 Key File format or the raw format into the NV index
handle 0x1000000.
# tpm2_nvdefine -C o \
-a "ownerread|ownerwrite" \
-s $(stat -c %s sealed.tpm) \
0x1000000
# tpm2_nvwrite -C o -i sealed.tpm 0x1000000
To unseal the key in GRUB, add the "tpm2_key_protector_init" command to
grub.cfg:
tpm2_key_protector_init --mode=nv --nvindex=0x1000000
cryptomount -u <UUID> --protector tpm2
To remove the NV index handle:
# tpm2_nvundefine -C o 0x1000000
Signed-off-by: Gary Lin <glin@suse.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
---
.../commands/tpm2_key_protector/module.c | 70 ++++++++++++++++---
1 file changed, 60 insertions(+), 10 deletions(-)
diff --git a/grub-core/commands/tpm2_key_protector/module.c b/grub-core/commands/tpm2_key_protector/module.c
index 795f61518..857f3753f 100644
--- a/grub-core/commands/tpm2_key_protector/module.c
+++ b/grub-core/commands/tpm2_key_protector/module.c
@@ -1133,10 +1133,9 @@ tpm2_protector_srk_recover (const tpm2_protector_context_t *ctx,
}
static grub_err_t
-tpm2_protector_nv_recover (const tpm2_protector_context_t *ctx,
- grub_uint8_t **key, grub_size_t *key_size)
+tpm2_protector_load_persistent (const tpm2_protector_context_t *ctx, TPM_HANDLE_t sealed_handle,
+ grub_uint8_t **key, grub_size_t *key_size)
{
- TPM_HANDLE_t sealed_handle = ctx->nv;
tpm2key_policy_t policy_seq = NULL;
bool dump_pcr = false;
grub_err_t err;
@@ -1163,6 +1162,51 @@ tpm2_protector_nv_recover (const tpm2_protector_context_t *ctx,
return err;
}
+static grub_err_t
+tpm2_protector_key_from_nvindex (const tpm2_protector_context_t *ctx, TPM_HANDLE_t nvindex,
+ grub_uint8_t **key, grub_size_t *key_size)
+{
+ TPMS_AUTH_COMMAND_t authCmd = {0};
+ TPM2B_NV_PUBLIC_t nv_public;
+ TPM2B_NAME_t nv_name;
+ grub_uint16_t data_size;
+ TPM2B_MAX_NV_BUFFER_t data;
+ TPM_RC_t rc;
+
+ /* Get the data size in the NV index handle */
+ rc = grub_tpm2_nv_readpublic (nvindex, NULL, &nv_public, &nv_name);
+ if (rc != TPM_RC_SUCCESS)
+ return grub_error (GRUB_ERR_BAD_ARGUMENT, "failed to retrieve info from 0x%x (TPM2_NV_ReadPublic: 0x%x)", nvindex, rc);
+
+ data_size = nv_public.nvPublic.dataSize;
+ if (data_size > TPM_MAX_NV_BUFFER_SIZE)
+ return grub_error (GRUB_ERR_BAD_ARGUMENT, "insufficient data buffer");
+
+ /* Read the data from the NV index handle */
+ authCmd.sessionHandle = TPM_RS_PW;
+ rc = grub_tpm2_nv_read (TPM_RH_OWNER, nvindex, &authCmd, data_size, 0, &data);
+ if (rc != TPM_RC_SUCCESS)
+ return grub_error (GRUB_ERR_BAD_ARGUMENT, "failed to read data from 0x%x (TPM2_NV_Read: 0x%x)", nvindex, rc);
+
+ return tpm2_protector_key_from_buffer (ctx, data.buffer, data_size, key, key_size);
+}
+
+static grub_err_t
+tpm2_protector_nv_recover (const tpm2_protector_context_t *ctx,
+ grub_uint8_t **key, grub_size_t *key_size)
+{
+ grub_err_t err;
+
+ if (TPM_HT_IS_PERSISTENT (ctx->nv) == true)
+ err = tpm2_protector_load_persistent (ctx, ctx->nv, key, key_size);
+ else if (TPM_HT_IS_NVINDEX (ctx->nv) == true)
+ err = tpm2_protector_key_from_nvindex (ctx, ctx->nv, key, key_size);
+ else
+ err = GRUB_ERR_BAD_ARGUMENT;
+
+ return err;
+}
+
static grub_err_t
tpm2_protector_recover (const tpm2_protector_context_t *ctx,
grub_uint8_t **key, grub_size_t *key_size)
@@ -1215,14 +1259,15 @@ tpm2_protector_check_args (tpm2_protector_context_t *ctx)
if (ctx->mode == TPM2_PROTECTOR_MODE_NV &&
(ctx->tpm2key != NULL || ctx->keyfile != NULL))
- return grub_error (GRUB_ERR_BAD_ARGUMENT, N_("in NV Index mode, a keyfile cannot be specified"));
+ return grub_error (GRUB_ERR_BAD_ARGUMENT, N_("a key file cannot be specified when using NV index mode"));
- if (ctx->mode == TPM2_PROTECTOR_MODE_NV && ctx->srk != 0)
- return grub_error (GRUB_ERR_BAD_ARGUMENT, N_("in NV Index mode, an SRK cannot be specified"));
+ if (ctx->mode == TPM2_PROTECTOR_MODE_NV && TPM_HT_IS_PERSISTENT (ctx->nv) == true &&
+ (ctx->srk != 0 || ctx->srk_type.type != TPM_ALG_ERROR))
+ return grub_error (GRUB_ERR_BAD_ARGUMENT, N_("an SRK cannot be specified when using NV index mode with a persistent handle"));
if (ctx->mode == TPM2_PROTECTOR_MODE_NV &&
- ctx->srk_type.type != TPM_ALG_ERROR)
- return grub_error (GRUB_ERR_BAD_ARGUMENT, N_("in NV Index mode, an asymmetric key type cannot be specified"));
+ (TPM_HT_IS_PERSISTENT (ctx->nv) == false && TPM_HT_IS_NVINDEX (ctx->nv) == false))
+ return grub_error (GRUB_ERR_BAD_ARGUMENT, N_("an NV index must be either a persistent handle or an NV index handle when using NV index mode"));
/* Defaults assignment */
if (ctx->bank == TPM_ALG_ERROR)
@@ -1234,8 +1279,13 @@ tpm2_protector_check_args (tpm2_protector_context_t *ctx)
ctx->pcr_count = 1;
}
- if (ctx->mode == TPM2_PROTECTOR_MODE_SRK &&
- ctx->srk_type.type == TPM_ALG_ERROR)
+ /*
+ * Set ECC_NIST_P256 as the default SRK when using SRK mode or NV mode with
+ * an NV index handle
+ */
+ if (ctx->srk_type.type == TPM_ALG_ERROR &&
+ (ctx->mode == TPM2_PROTECTOR_MODE_SRK ||
+ (ctx->mode == TPM2_PROTECTOR_MODE_NV && TPM_HT_IS_NVINDEX (ctx->nv) == true)))
{
ctx->srk_type.type = TPM_ALG_ECC;
ctx->srk_type.detail.ecc_curve = TPM_ECC_NIST_P256;
--
2.43.0
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