| Message ID | 20200922022809.7105-4-James.Bottomley@HansenPartnership.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | TPM 2.0 trusted key rework | expand |
On Mon, Sep 21, 2020 at 07:28:07PM -0700, James Bottomley wrote: > In TPM 1.2 an authorization was a 20 byte number. The spec actually > recommended you to hash variable length passwords and use the sha1 > hash as the authorization. Because the spec doesn't require this > hashing, the current authorization for trusted keys is a 40 digit hex > number. For TPM 2.0 the spec allows the passing in of variable length > passwords and passphrases directly, so we should allow that in trusted > keys for ease of use. Update the 'blobauth' parameter to take this > into account, so we can now use plain text passwords for the keys. > > so before > > keyctl add trusted kmk "new 32 blobauth=f572d396fae9206628714fb2ce00f72e94f2258fkeyhandle=81000001" @u > > after we will accept both the old hex sha1 form as well as a new > directly supplied password: > > keyctl add trusted kmk "new 32 blobauth=hello keyhandle=81000001" @u I'm still getting -EINVAL from both with a Geminilake NUC. /Jarkko
On Fri, 2020-09-25 at 10:28 +0300, Jarkko Sakkinen wrote: > On Mon, Sep 21, 2020 at 07:28:07PM -0700, James Bottomley wrote: [...] > > keyctl add trusted kmk "new 32 > > blobauth=f572d396fae9206628714fb2ce00f72e94f2258fkeyhandle=81000001 > > " @u > > > > after we will accept both the old hex sha1 form as well as a new > > directly supplied password: > > > > keyctl add trusted kmk "new 32 blobauth=hello keyhandle=81000001" > > @u > > I'm still getting -EINVAL from both with a Geminilake NUC. Since I don't have one of those you're going to have to give me more to go on. I've tested this works in a VM with the ibmtss and on a Rainbow Pass with a variety of physical TPMs. Keyctl returns -EINVAL for an annoying number of conditions it shouldn't ... the most frequent of which is that the key already exists in the keyring. So what's different about the Geminilake NUC? Either it's a kernel problem with the TPM, in which case there should be something in dmesg or it's a userspace problem with keyctl, in which case perhaps strace might get us further forward. James
On Fri, Sep 25, 2020 at 10:39:23AM -0700, James Bottomley wrote: > On Fri, 2020-09-25 at 10:28 +0300, Jarkko Sakkinen wrote: > > On Mon, Sep 21, 2020 at 07:28:07PM -0700, James Bottomley wrote: > [...] > > > keyctl add trusted kmk "new 32 > > > blobauth=f572d396fae9206628714fb2ce00f72e94f2258fkeyhandle=81000001 > > > " @u > > > > > > after we will accept both the old hex sha1 form as well as a new > > > directly supplied password: > > > > > > keyctl add trusted kmk "new 32 blobauth=hello keyhandle=81000001" > > > @u > > > > I'm still getting -EINVAL from both with a Geminilake NUC. > > Since I don't have one of those you're going to have to give me more to > go on. I've tested this works in a VM with the ibmtss and on a Rainbow > Pass with a variety of physical TPMs. Keyctl returns -EINVAL for an > annoying number of conditions it shouldn't ... the most frequent of > which is that the key already exists in the keyring. > > So what's different about the Geminilake NUC? Either it's a kernel > problem with the TPM, in which case there should be something in dmesg > or it's a userspace problem with keyctl, in which case perhaps strace > might get us further forward. > > James I'll debug it further sometime next week, just acknowledged the issue. I'll use bpftrace for the purpose. In your environment, would be interesting to see what happens if you use tpm2-root-key to generate the key instead of IBMTSS. It is now available here: https://git.kernel.org/pub/scm/linux/kernel/git/jarkko/tpm2-scripts.git/ /Jarkko
On Mon, Sep 21, 2020 at 07:28:07PM -0700, James Bottomley wrote: > In TPM 1.2 an authorization was a 20 byte number. The spec actually > recommended you to hash variable length passwords and use the sha1 > hash as the authorization. Because the spec doesn't require this > hashing, the current authorization for trusted keys is a 40 digit hex > number. For TPM 2.0 the spec allows the passing in of variable length > passwords and passphrases directly, so we should allow that in trusted > keys for ease of use. Update the 'blobauth' parameter to take this > into account, so we can now use plain text passwords for the keys. > > so before > > keyctl add trusted kmk "new 32 blobauth=f572d396fae9206628714fb2ce00f72e94f2258fkeyhandle=81000001" @u > > after we will accept both the old hex sha1 form as well as a new > directly supplied password: > > keyctl add trusted kmk "new 32 blobauth=hello keyhandle=81000001" @u > > Since a sha1 hex code must be exactly 40 bytes long and a direct > password must be 20 or less, we use the length as the discriminator > for which form is input. > > Note this is both and enhancement and a potential bug fix. The TPM > 2.0 spec requires us to strip leading zeros, meaning empyty > authorization is a zero length HMAC whereas we're currently passing in > 20 bytes of zeros. A lot of TPMs simply accept this as OK, but the > Microsoft TPM emulator rejects it with TPM_RC_BAD_AUTH, so this patch > makes the Microsoft TPM emulator work with trusted keys. > > Fixes: 0fe5480303a1 ("keys, trusted: seal/unseal with TPM 2.0 chips") > Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com> > Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> > > --- > > v6: change comment, eliminate else clauses and add fixes tag > v7: fixes before signoff > v12: fix mismerge from v6 to make processing continue after blobauth > > Merge with auth fix > --- > include/keys/trusted-type.h | 1 + > security/keys/trusted-keys/trusted_tpm1.c | 32 ++++++++++++++++++----- > security/keys/trusted-keys/trusted_tpm2.c | 10 ++++--- > 3 files changed, 33 insertions(+), 10 deletions(-) > > diff --git a/include/keys/trusted-type.h b/include/keys/trusted-type.h > index a94c03a61d8f..b2ed3481c6a0 100644 > --- a/include/keys/trusted-type.h > +++ b/include/keys/trusted-type.h > @@ -30,6 +30,7 @@ struct trusted_key_options { > uint16_t keytype; > uint32_t keyhandle; > unsigned char keyauth[TPM_DIGEST_SIZE]; > + uint32_t blobauth_len; > unsigned char blobauth[TPM_DIGEST_SIZE]; > uint32_t pcrinfo_len; > unsigned char pcrinfo[MAX_PCRINFO_SIZE]; > diff --git a/security/keys/trusted-keys/trusted_tpm1.c b/security/keys/trusted-keys/trusted_tpm1.c > index b9fe02e5f84f..eaa2e7ca136e 100644 > --- a/security/keys/trusted-keys/trusted_tpm1.c > +++ b/security/keys/trusted-keys/trusted_tpm1.c > @@ -781,13 +781,33 @@ static int getoptions(char *c, struct trusted_key_payload *pay, > return -EINVAL; > break; > case Opt_blobauth: > - if (strlen(args[0].from) != 2 * SHA1_DIGEST_SIZE) > - return -EINVAL; > - res = hex2bin(opt->blobauth, args[0].from, > - SHA1_DIGEST_SIZE); > - if (res < 0) > - return -EINVAL; > + /* > + * TPM 1.2 authorizations are sha1 hashes passed in as > + * hex strings. TPM 2.0 authorizations are simple > + * passwords (although it can take a hash as well) > + */ > + opt->blobauth_len = strlen(args[0].from); > + > + if (opt->blobauth_len == 2 * TPM_DIGEST_SIZE) { > + res = hex2bin(opt->blobauth, args[0].from, > + TPM_DIGEST_SIZE); > + if (res < 0) > + return -EINVAL; > + > + opt->blobauth_len = TPM_DIGEST_SIZE; > + break; > + } > + > + if (tpm2 && opt->blobauth_len <= sizeof(opt->blobauth)) { > + memcpy(opt->blobauth, args[0].from, > + opt->blobauth_len); > + break; > + } > + > + return -EINVAL; > + > break; > + > case Opt_migratable: > if (*args[0].from == '0') > pay->migratable = 0; > diff --git a/security/keys/trusted-keys/trusted_tpm2.c b/security/keys/trusted-keys/trusted_tpm2.c > index 08ec7f48f01d..b4a5058107c2 100644 > --- a/security/keys/trusted-keys/trusted_tpm2.c > +++ b/security/keys/trusted-keys/trusted_tpm2.c > @@ -91,10 +91,12 @@ int tpm2_seal_trusted(struct tpm_chip *chip, > TPM_DIGEST_SIZE); > > /* sensitive */ > - tpm_buf_append_u16(&buf, 4 + TPM_DIGEST_SIZE + payload->key_len + 1); > + tpm_buf_append_u16(&buf, 4 + options->blobauth_len + payload->key_len + 1); > + > + tpm_buf_append_u16(&buf, options->blobauth_len); > + if (options->blobauth_len) > + tpm_buf_append(&buf, options->blobauth, options->blobauth_len); > > - tpm_buf_append_u16(&buf, TPM_DIGEST_SIZE); > - tpm_buf_append(&buf, options->blobauth, TPM_DIGEST_SIZE); > tpm_buf_append_u16(&buf, payload->key_len + 1); > tpm_buf_append(&buf, payload->key, payload->key_len); > tpm_buf_append_u8(&buf, payload->migratable); > @@ -258,7 +260,7 @@ static int tpm2_unseal_cmd(struct tpm_chip *chip, > NULL /* nonce */, 0, > TPM2_SA_CONTINUE_SESSION, > options->blobauth /* hmac */, > - TPM_DIGEST_SIZE); > + options->blobauth_len); > > rc = tpm_send(chip, buf.data, tpm_buf_length(&buf)); > if (rc > 0) > -- > 2.26.2 > Tested-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> Transcript: ➜ tpm2-scripts (master) ✗ sudo ./tpm2-root-key 0x80000000 ➜ tpm2-scripts (master) ✗ sudo keyctl add trusted kmk "new 32 blobauth=hello keyhandle=80000000" @u 751240563 /Jarkko
diff --git a/include/keys/trusted-type.h b/include/keys/trusted-type.h index a94c03a61d8f..b2ed3481c6a0 100644 --- a/include/keys/trusted-type.h +++ b/include/keys/trusted-type.h @@ -30,6 +30,7 @@ struct trusted_key_options { uint16_t keytype; uint32_t keyhandle; unsigned char keyauth[TPM_DIGEST_SIZE]; + uint32_t blobauth_len; unsigned char blobauth[TPM_DIGEST_SIZE]; uint32_t pcrinfo_len; unsigned char pcrinfo[MAX_PCRINFO_SIZE]; diff --git a/security/keys/trusted-keys/trusted_tpm1.c b/security/keys/trusted-keys/trusted_tpm1.c index b9fe02e5f84f..eaa2e7ca136e 100644 --- a/security/keys/trusted-keys/trusted_tpm1.c +++ b/security/keys/trusted-keys/trusted_tpm1.c @@ -781,13 +781,33 @@ static int getoptions(char *c, struct trusted_key_payload *pay, return -EINVAL; break; case Opt_blobauth: - if (strlen(args[0].from) != 2 * SHA1_DIGEST_SIZE) - return -EINVAL; - res = hex2bin(opt->blobauth, args[0].from, - SHA1_DIGEST_SIZE); - if (res < 0) - return -EINVAL; + /* + * TPM 1.2 authorizations are sha1 hashes passed in as + * hex strings. TPM 2.0 authorizations are simple + * passwords (although it can take a hash as well) + */ + opt->blobauth_len = strlen(args[0].from); + + if (opt->blobauth_len == 2 * TPM_DIGEST_SIZE) { + res = hex2bin(opt->blobauth, args[0].from, + TPM_DIGEST_SIZE); + if (res < 0) + return -EINVAL; + + opt->blobauth_len = TPM_DIGEST_SIZE; + break; + } + + if (tpm2 && opt->blobauth_len <= sizeof(opt->blobauth)) { + memcpy(opt->blobauth, args[0].from, + opt->blobauth_len); + break; + } + + return -EINVAL; + break; + case Opt_migratable: if (*args[0].from == '0') pay->migratable = 0; diff --git a/security/keys/trusted-keys/trusted_tpm2.c b/security/keys/trusted-keys/trusted_tpm2.c index 08ec7f48f01d..b4a5058107c2 100644 --- a/security/keys/trusted-keys/trusted_tpm2.c +++ b/security/keys/trusted-keys/trusted_tpm2.c @@ -91,10 +91,12 @@ int tpm2_seal_trusted(struct tpm_chip *chip, TPM_DIGEST_SIZE); /* sensitive */ - tpm_buf_append_u16(&buf, 4 + TPM_DIGEST_SIZE + payload->key_len + 1); + tpm_buf_append_u16(&buf, 4 + options->blobauth_len + payload->key_len + 1); + + tpm_buf_append_u16(&buf, options->blobauth_len); + if (options->blobauth_len) + tpm_buf_append(&buf, options->blobauth, options->blobauth_len); - tpm_buf_append_u16(&buf, TPM_DIGEST_SIZE); - tpm_buf_append(&buf, options->blobauth, TPM_DIGEST_SIZE); tpm_buf_append_u16(&buf, payload->key_len + 1); tpm_buf_append(&buf, payload->key, payload->key_len); tpm_buf_append_u8(&buf, payload->migratable); @@ -258,7 +260,7 @@ static int tpm2_unseal_cmd(struct tpm_chip *chip, NULL /* nonce */, 0, TPM2_SA_CONTINUE_SESSION, options->blobauth /* hmac */, - TPM_DIGEST_SIZE); + options->blobauth_len); rc = tpm_send(chip, buf.data, tpm_buf_length(&buf)); if (rc > 0)
In TPM 1.2 an authorization was a 20 byte number. The spec actually recommended you to hash variable length passwords and use the sha1 hash as the authorization. Because the spec doesn't require this hashing, the current authorization for trusted keys is a 40 digit hex number. For TPM 2.0 the spec allows the passing in of variable length passwords and passphrases directly, so we should allow that in trusted keys for ease of use. Update the 'blobauth' parameter to take this into account, so we can now use plain text passwords for the keys. so before keyctl add trusted kmk "new 32 blobauth=f572d396fae9206628714fb2ce00f72e94f2258fkeyhandle=81000001" @u after we will accept both the old hex sha1 form as well as a new directly supplied password: keyctl add trusted kmk "new 32 blobauth=hello keyhandle=81000001" @u Since a sha1 hex code must be exactly 40 bytes long and a direct password must be 20 or less, we use the length as the discriminator for which form is input. Note this is both and enhancement and a potential bug fix. The TPM 2.0 spec requires us to strip leading zeros, meaning empyty authorization is a zero length HMAC whereas we're currently passing in 20 bytes of zeros. A lot of TPMs simply accept this as OK, but the Microsoft TPM emulator rejects it with TPM_RC_BAD_AUTH, so this patch makes the Microsoft TPM emulator work with trusted keys. Fixes: 0fe5480303a1 ("keys, trusted: seal/unseal with TPM 2.0 chips") Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com> Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> --- v6: change comment, eliminate else clauses and add fixes tag v7: fixes before signoff v12: fix mismerge from v6 to make processing continue after blobauth Merge with auth fix --- include/keys/trusted-type.h | 1 + security/keys/trusted-keys/trusted_tpm1.c | 32 ++++++++++++++++++----- security/keys/trusted-keys/trusted_tpm2.c | 10 ++++--- 3 files changed, 33 insertions(+), 10 deletions(-)