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pcr-oracle
support-ecc-srk.patch
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File support-ecc-srk.patch of Package pcr-oracle
From 60ce42dbf61ce89012d9bc71c92c5cc92759b02c Mon Sep 17 00:00:00 2001 From: Gary Lin <glin@suse.com> Date: Wed, 3 Apr 2024 14:41:49 +0800 Subject: [PATCH 1/3] Update the comment for SRK template USERWITHAUTH and NODA are set according to "TCG TPM v2.0 Provisioning Guidance". This commit updates the comment to add the reference. Signed-off-by: Gary Lin <glin@suse.com> --- src/pcr-policy.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/src/pcr-policy.c b/src/pcr-policy.c index 8f2c42c..f03b6e0 100644 --- a/src/pcr-policy.c +++ b/src/pcr-policy.c @@ -67,8 +67,9 @@ static TPM2B_PUBLIC SRK_template = { .publicArea = { .type = TPM2_ALG_RSA, .nameAlg = TPM2_ALG_SHA256, - /* For reasons not clear to me, grub2 derives the SRK using the NODA attribute, - * which means it is not subject to dictionary attack protections. */ + /* Per "Storage Primary Key (SRK) Templates" in section 7.5.1 of + * TCG TPM v2.0 Provisioning Guidance 1.0 Revision 1.0, the + * template for shared SRKs sets USERWITHAUTH and NODA. */ .objectAttributes = TPMA_OBJECT_RESTRICTED|TPMA_OBJECT_DECRYPT \ |TPMA_OBJECT_FIXEDTPM|TPMA_OBJECT_FIXEDPARENT \ |TPMA_OBJECT_SENSITIVEDATAORIGIN|TPMA_OBJECT_USERWITHAUTH \ -- 2.35.3 From 0085c5a6a47f433dc69739c54b9db11796aff62e Mon Sep 17 00:00:00 2001 From: Gary Lin <glin@suse.com> Date: Wed, 10 Apr 2024 16:20:44 +0800 Subject: [PATCH 2/3] Support SRK template with ECC_NIST_P256 When sealing data with SRK, the data is actually encrypted with the symmetric key, and the selection of the asymmetric algorithm is only a parameter for KDF to derive the symmetric key. Compared with RSA, ECC NIST-P256 provides the faster key generation, so it's a better choice for the SRK template in general. This commit adds a new option, '--ecc-srk', to switch the default SRK template from the RSA one to the ECC one, so that the user can specify the SRK template when sealing/unsealing data. Signed-off-by: Gary Lin <glin@suse.com> --- src/oracle.c | 7 +++++++ src/pcr-policy.c | 44 +++++++++++++++++++++++++++++++++++++++++--- src/pcr.h | 1 + 3 files changed, 49 insertions(+), 3 deletions(-) diff --git a/src/oracle.c b/src/oracle.c index 1cafafc..f391430 100644 --- a/src/oracle.c +++ b/src/oracle.c @@ -92,6 +92,7 @@ enum { OPT_RSA_PUBLIC_KEY, OPT_RSA_GENERATE_KEY, OPT_RSA_BITS, + OPT_ECC_SRK, OPT_INPUT, OPT_OUTPUT, OPT_AUTHORIZED_POLICY, @@ -125,6 +126,7 @@ static struct option options[] = { { "public-key", required_argument, 0, OPT_RSA_PUBLIC_KEY }, { "rsa-generate-key", no_argument, 0, OPT_RSA_GENERATE_KEY }, { "rsa-bits", required_argument, 0, OPT_RSA_BITS }, + { "ecc-srk", no_argument, 0, OPT_ECC_SRK }, { "input", required_argument, 0, OPT_INPUT }, { "output", required_argument, 0, OPT_OUTPUT }, { "authorized-policy", required_argument, 0, OPT_AUTHORIZED_POLICY }, @@ -1042,6 +1044,8 @@ main(int argc, char **argv) unsigned int rsa_bits = 2048; int c, exit_code = 0; + set_srk_alg("RSA"); + while ((c = getopt_long(argc, argv, "dhA:CF:LSZ", options, NULL)) != EOF) { switch (c) { case 'A': @@ -1109,6 +1113,9 @@ main(int argc, char **argv) case OPT_RSA_BITS: opt_rsa_bits = optarg; break; + case OPT_ECC_SRK: + set_srk_alg("ECC"); + break; case OPT_INPUT: opt_input = optarg; break; diff --git a/src/pcr-policy.c b/src/pcr-policy.c index f03b6e0..f65becf 100644 --- a/src/pcr-policy.c +++ b/src/pcr-policy.c @@ -62,7 +62,7 @@ struct target_platform { const stored_key_t *public_key_file); }; -static TPM2B_PUBLIC SRK_template = { +static TPM2B_PUBLIC RSA_SRK_template = { .size = sizeof(TPMT_PUBLIC), .publicArea = { .type = TPM2_ALG_RSA, @@ -88,6 +88,35 @@ static TPM2B_PUBLIC SRK_template = { } }; +static TPM2B_PUBLIC ECC_SRK_template = { + .size = sizeof(TPMT_PUBLIC), + .publicArea = { + .type = TPM2_ALG_ECC, + .nameAlg = TPM2_ALG_SHA256, + /* Per "Storage Primary Key (SRK) Templates" in section 7.5.1 of + * TCG TPM v2.0 Provisioning Guidance 1.0 Revision 1.0, the + * template for shared SRKs sets USERWITHAUTH and NODA. */ + .objectAttributes = TPMA_OBJECT_RESTRICTED|TPMA_OBJECT_DECRYPT \ + |TPMA_OBJECT_FIXEDTPM|TPMA_OBJECT_FIXEDPARENT \ + |TPMA_OBJECT_SENSITIVEDATAORIGIN|TPMA_OBJECT_USERWITHAUTH \ + |TPMA_OBJECT_NODA, + .parameters = { + .eccDetail = { + .symmetric = { + .algorithm = TPM2_ALG_AES, + .keyBits = { .sym = 128 }, + .mode = { .sym = TPM2_ALG_CFB }, + }, + .scheme = { TPM2_ALG_NULL }, + .curveID = TPM2_ECC_NIST_P256, + .kdf.scheme = TPM2_ALG_NULL + } + } + } +}; + +static const TPM2B_PUBLIC *SRK_template; + static const TPM2B_PUBLIC seal_public_template = { .size = sizeof(TPMT_PUBLIC), .publicArea = { @@ -107,10 +136,19 @@ static const TPM2B_PUBLIC seal_public_template = { } }; +void +set_srk_alg (const char *alg) +{ + if (strcmp(alg, "RSA") == 0) + SRK_template = &RSA_SRK_template; + else + SRK_template = &ECC_SRK_template; +} + void set_srk_rsa_bits (const unsigned int rsa_bits) { - SRK_template.publicArea.parameters.rsaDetail.keyBits = rsa_bits; + RSA_SRK_template.publicArea.parameters.rsaDetail.keyBits = rsa_bits; } static inline const tpm_evdigest_t * @@ -609,7 +647,7 @@ esys_create_primary(ESYS_CONTEXT *esys_context, ESYS_TR *handle_ret) t0 = timing_begin(); rc = Esys_CreatePrimary(esys_context, ESYS_TR_RH_OWNER, ESYS_TR_PASSWORD, - ESYS_TR_NONE, ESYS_TR_NONE, &in_sensitive, &SRK_template, + ESYS_TR_NONE, ESYS_TR_NONE, &in_sensitive, SRK_template, NULL, &creation_pcr, handle_ret, NULL, NULL, NULL, NULL); diff --git a/src/pcr.h b/src/pcr.h index 4d8f816..f1dc9af 100644 --- a/src/pcr.h +++ b/src/pcr.h @@ -39,6 +39,7 @@ typedef struct tpm_pcr_selection { const tpm_algo_info_t * algo_info; } tpm_pcr_selection_t; +extern void set_srk_alg (const char *alg); extern void set_srk_rsa_bits (const unsigned int rsa_bits); extern void pcr_bank_initialize(tpm_pcr_bank_t *bank, unsigned int pcr_mask, const tpm_algo_info_t *algo); extern bool pcr_bank_wants_pcr(tpm_pcr_bank_t *bank, unsigned int index); -- 2.35.3 From 207bd496868d65455e63aa9586bfc6e02900a4a1 Mon Sep 17 00:00:00 2001 From: Gary Lin <glin@suse.com> Date: Wed, 24 Apr 2024 14:53:25 +0800 Subject: [PATCH 3/3] Update to conform the latest TPM 2.0 Key File For TPM 2.0 Key File, the default asymmetric algorithm of SRK is ECC NIST-P256, not RSA 2048. A new field 'rsaParent' is introduced to note the key is sealed with RSA SRK. This commit implements two new fields: description and rsaParent in tpm2key.c/tpm2key-asn.h and sets rsaParent when RSA SRK is used to seal the key. When unsealing a tpm2key, the SRK template is set to the RSA template if rsaParent is TRUE. Otherwise, the SRK template is switched to the ECC SRK template. A new testing script, test-tpm2key-ecc.sh, is also added to test the tpm2key file sealed with ECC SRK. Signed-off-by: Gary Lin <glin@suse.com> --- src/pcr-policy.c | 8 +++ src/tpm2key-asn.h | 4 ++ src/tpm2key.c | 2 + test-tpm2key-ecc.sh | 127 ++++++++++++++++++++++++++++++++++++++++++++ 4 files changed, 141 insertions(+) create mode 100755 test-tpm2key-ecc.sh diff --git a/src/pcr-policy.c b/src/pcr-policy.c index f65becf..90f60ff 100644 --- a/src/pcr-policy.c +++ b/src/pcr-policy.c @@ -1505,6 +1505,11 @@ tpm2key_unseal_secret(const char *input_path, const char *output_path, if (!tpm2key_read_file(input_path, &tpm2key)) return false; + if (tpm2key->rsaParent == 1) + SRK_template = &RSA_SRK_template; + else + SRK_template = &ECC_SRK_template; + buffer_init_read(&buf, tpm2key->pubkey->data, tpm2key->pubkey->length); rc = Tss2_MU_TPM2B_PUBLIC_Unmarshal(buf.data, buf.size, &buf.rpos, &pub); if (rc != TSS2_RC_SUCCESS) @@ -1634,6 +1639,9 @@ tpm2key_write_sealed_secret(const char *pathname, if (!tpm2key_basekey(&tpm2key, TPM2_RH_OWNER, sealed_public, sealed_private)) goto cleanup; + if (SRK_template->publicArea.type == TPM2_ALG_RSA) + tpm2key->rsaParent = 1; + if (pcr_sel && !tpm2key_add_policy_policypcr(tpm2key, pcr_sel)) goto cleanup; diff --git a/src/tpm2key-asn.h b/src/tpm2key-asn.h index 3f1c0d7..d0cdfaa 100644 --- a/src/tpm2key-asn.h +++ b/src/tpm2key-asn.h @@ -77,6 +77,8 @@ DEFINE_STACK_OF(TSSAUTHPOLICY); * policy [1] EXPLICIT SEQUENCE OF TPMPolicy OPTIONAL * secret [2] EXPLICIT OCTET STRING OPTIONAL * authPolicy [3] EXPLICIT SEQUENCE OF TPMAuthPolicy OPTIONAL + * description [4] EXPLICIT UTF8String OPTIONAL + * rsaParent [5] EXPLICIT BOOLEAN OPTIONAL * parent INTEGER * pubkey OCTET STRING * privkey OCTET STRING @@ -89,6 +91,8 @@ typedef struct { STACK_OF(TSSOPTPOLICY) *policy; ASN1_OCTET_STRING *secret; STACK_OF(TSSAUTHPOLICY) *authPolicy; + ASN1_UTF8STRING description; + ASN1_BOOLEAN rsaParent; ASN1_INTEGER *parent; ASN1_OCTET_STRING *pubkey; ASN1_OCTET_STRING *privkey; diff --git a/src/tpm2key.c b/src/tpm2key.c index cabd791..af4c984 100644 --- a/src/tpm2key.c +++ b/src/tpm2key.c @@ -278,6 +278,8 @@ ASN1_SEQUENCE(TSSPRIVKEY) = { ASN1_EXP_SEQUENCE_OF_OPT(TSSPRIVKEY, policy, TSSOPTPOLICY, 1), ASN1_EXP_OPT(TSSPRIVKEY, secret, ASN1_OCTET_STRING, 2), ASN1_EXP_SEQUENCE_OF_OPT(TSSPRIVKEY, authPolicy, TSSAUTHPOLICY, 3), + ASN1_EXP_OPT(TSSPRIVKEY, description, ASN1_UTF8STRING, 4), + ASN1_EXP_OPT(TSSPRIVKEY, rsaParent, ASN1_BOOLEAN, 5), ASN1_SIMPLE(TSSPRIVKEY, parent, ASN1_INTEGER), ASN1_SIMPLE(TSSPRIVKEY, pubkey, ASN1_OCTET_STRING), ASN1_SIMPLE(TSSPRIVKEY, privkey, ASN1_OCTET_STRING) diff --git a/test-tpm2key-ecc.sh b/test-tpm2key-ecc.sh new file mode 100755 index 0000000..d87acff --- /dev/null +++ b/test-tpm2key-ecc.sh @@ -0,0 +1,127 @@ +#!/bin/bash +# +# This script needs to be run with root privilege +# + +# TESTDIR=policy.test +PCR_MASK=0,2,4,12 + +pcr_oracle=pcr-oracle +if [ -x pcr-oracle ]; then + pcr_oracle=$PWD/pcr-oracle +fi + +function call_oracle { + + echo "****************" + echo "pcr-oracle $*" + $pcr_oracle --target-platform tpm2.0 -d "$@" +} + +if [ -z "$TESTDIR" ]; then + tmpdir=$(mktemp -d /tmp/pcrtestXXXXXX) + trap "cd / && rm -rf $tmpdir" 0 1 2 10 11 15 + + TESTDIR=$tmpdir +fi + +trap "echo 'FAIL: command exited with error'; exit 1" ERR + +echo "This is super secret" >$TESTDIR/secret + +set -e +cd $TESTDIR + +echo "Seal the secret with PCR policy" +call_oracle \ + --from current \ + --input secret \ + --output sealed \ + --ecc-srk \ + seal-secret $PCR_MASK + +echo "Unseal the sealed with PCR policy" +call_oracle \ + --input sealed \ + --output recovered \ + unseal-secret + +if ! cmp secret recovered; then + echo "BAD: Unable to recover original secret" + echo "Secret:" + od -tx1c secret + echo "Recovered:" + od -tx1c recovered + exit 1 +else + echo "NICE: we were able to recover the original secret" +fi + +rm -f sealed recovered + +call_oracle \ + --rsa-generate-key \ + --private-key policy-key.pem \ + --auth authorized.policy \ + create-authorized-policy $PCR_MASK + +call_oracle \ + --private-key policy-key.pem \ + --public-key policy-pubkey \ + store-public-key + +call_oracle \ + --auth authorized.policy \ + --input secret \ + --output sealed \ + --ecc-srk \ + seal-secret + +for attempt in first second; do + echo "Sign the set of PCRs we want to authorize" + call_oracle \ + --policy-name "authorized-policy-test" \ + --private-key policy-key.pem \ + --from current \ + --input sealed \ + --output sealed-signed \ + sign $PCR_MASK + + echo "$attempt attempt to unseal the secret" + call_oracle \ + --input sealed-signed \ + --output recovered \ + unseal-secret + + if ! cmp secret recovered; then + echo "BAD: Unable to recover original secret" + echo "Secret:" + od -tx1c secret + echo "Recovered:" + od -tx1c recovered + exit 1 + else + echo "NICE: we were able to recover the original secret" + fi + + if [ "$attempt" = "second" ]; then + break + fi + + echo "Extend PCR 12. Unsealing should fail afterwards" + tpm2_pcrextend 12:sha256=21d2013e3081f1e455fdd5ba6230a8620c3cfc9a9c31981d857fe3891f79449e + rm -f recovered + call_oracle \ + --input sealed-signed \ + --output recovered \ + unseal-secret || true + + if [ -s recovered ] && ! cmp secret recovered; then + echo "BAD: We were still able to recover the original secret. Something stinks" + exit 1 + else + echo "GOOD: After changing a PCR, the secret can no longer be unsealed" + fi + + echo "Now recreate the signed PCR policy" +done -- 2.35.3
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