From: James Bottomley <James.Bottomley@HansenPartnership.com>
To: linux-integrity@vger.kernel.org
Cc: Mimi Zohar <zohar@linux.ibm.com>,
Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>,
David Woodhouse <dwmw2@infradead.org>,
keyrings@vger.kernel.org, David Howells <dhowells@redhat.com>
Subject: [PATCH v10 7/8] security: keys: trusted: add ability to specify arbitrary policy
Date: Tue, 16 Jun 2020 09:02:28 -0700 [thread overview]
Message-ID: <20200616160229.8018-8-James.Bottomley@HansenPartnership.com> (raw)
In-Reply-To: <20200616160229.8018-1-James.Bottomley@HansenPartnership.com>
This patch adds a policy= argument to key creation. The policy is the
standard tss policymaker format and each separate policy line must
have a newline after it.
Thus to construct a policy requiring authorized value and pcr 16
locking using a sha256 hash, the policy (policy.txt) file would be two
lines:
0000017F00000001000B03000001303095B49BE85E381E5B20E557E46363EF55B0F43B132C2D8E3DE9AC436656F2
0000016b
This can be inserted into the key with
keyctl add trusted kmk "new 32 policy=`cat policy.txt` keyhandle=0x81000001 hash=sha256" @u
Note that although a few policies work like this, most require special
handling which must be added to the kernel policy construction
routine.
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
---
.../security/keys/trusted-encrypted.rst | 16 ++++++
security/keys/trusted-keys/tpm2-policy.c | 53 +++++++++++++++++++
security/keys/trusted-keys/tpm2-policy.h | 1 +
security/keys/trusted-keys/trusted_tpm1.c | 15 ++++++
4 files changed, 85 insertions(+)
diff --git a/Documentation/security/keys/trusted-encrypted.rst b/Documentation/security/keys/trusted-encrypted.rst
index 053344c4df5b..b68d3eb73f00 100644
--- a/Documentation/security/keys/trusted-encrypted.rst
+++ b/Documentation/security/keys/trusted-encrypted.rst
@@ -76,6 +76,9 @@ Usage::
policyhandle= handle to an authorization policy session that defines the
same policy and with the same hash algorithm as was used to
seal the key.
+ policy= specify an arbitrary set of policies. These must
+ be in policymaker format with each separate
+ policy line newline terminated.
"keyctl print" returns an ascii hex copy of the sealed key, which is in standard
TPM_STORED_DATA format. The key length for new keys are always in bytes.
@@ -168,6 +171,19 @@ zeros (the value of PCR 16)::
$ dd if=/dev/zero bs=1 count=20 2>/dev/null|sha1sum
6768033e216468247bd031a0a2d9876d79818f8f
+You can also specify arbitrary policy in policymaker format, so a two
+value policy (the pcr example above and authvalue) would look like
+this in policymaker format::
+
+ 0000017F000000010004030000016768033e216468247bd031a0a2d9876d79818f8f
+ 0000016b
+
+This can be placed in a file (say policy.txt) and then added to the key as::
+
+ $ keyctl add trusted kmk "new 32 keyhandle=0x81000001 hash=sha1 policy=`cat policy.txt`" @u
+
+The newlines in the file policy.txt will be automatically processed.
+
Reseal a trusted key under new pcr values::
$ keyctl update 268728824 "update pcrinfo=`cat pcr.blob`"
diff --git a/security/keys/trusted-keys/tpm2-policy.c b/security/keys/trusted-keys/tpm2-policy.c
index 080a76e879fd..87a13e607eca 100644
--- a/security/keys/trusted-keys/tpm2-policy.c
+++ b/security/keys/trusted-keys/tpm2-policy.c
@@ -370,3 +370,56 @@ int tpm2_get_policy_session(struct tpm_chip *chip, struct tpm2_policies *pols,
return 0;
}
+
+int tpm2_parse_policies(struct tpm2_policies **ppols, char *str)
+{
+ struct tpm2_policies *pols;
+ char *p;
+ u8 *ptr;
+ int i = 0, left = PAGE_SIZE, res;
+
+ pols = kmalloc(left, GFP_KERNEL);
+ if (!pols)
+ return -ENOMEM;
+
+ ptr = (u8 *)(pols + 1);
+ left -= ptr - (u8 *)pols;
+
+ while ((p = strsep(&str, "\n"))) {
+ if (*p == '\0' || *p == '\n')
+ continue;
+
+ pols->len[i] = strlen(p)/2;
+ if (pols->len[i] > left) {
+ res = -E2BIG;
+ goto err;
+ }
+
+ res = hex2bin(ptr, p, pols->len[i]);
+ if (res)
+ goto err;
+
+ /* get command code and skip past */
+ pols->code[i] = get_unaligned_be32(ptr);
+ pols->policies[i] = ptr + 4;
+ ptr += pols->len[i];
+ left -= pols->len[i];
+ pols->len[i] -= 4;
+
+ /*
+ * FIXME: this does leave the code embedded in dead
+ * regions of the memory, but it's easier than
+ * hexdumping to a temporary or copying over
+ */
+ i++;
+ }
+
+ pols->count = i;
+ *ppols = pols;
+
+ return 0;
+
+ err:
+ kfree(pols);
+ return res;
+}
diff --git a/security/keys/trusted-keys/tpm2-policy.h b/security/keys/trusted-keys/tpm2-policy.h
index 46bf1f0a9325..0da013116c1c 100644
--- a/security/keys/trusted-keys/tpm2-policy.h
+++ b/security/keys/trusted-keys/tpm2-policy.h
@@ -28,3 +28,4 @@ int tpm2_generate_policy_digest(struct tpm2_policies *pols, u32 hash,
int tpm2_encode_policy(struct tpm2_policies *pols, u8 **data, u32 *len);
int tpm2_get_policy_session(struct tpm_chip *chip, struct tpm2_policies *pols,
u32 *handle);
+int tpm2_parse_policies(struct tpm2_policies **ppols, char *str);
diff --git a/security/keys/trusted-keys/trusted_tpm1.c b/security/keys/trusted-keys/trusted_tpm1.c
index 9f735bbe9eef..d8b073ebe167 100644
--- a/security/keys/trusted-keys/trusted_tpm1.c
+++ b/security/keys/trusted-keys/trusted_tpm1.c
@@ -29,6 +29,8 @@
#include <keys/trusted_tpm.h>
+#include "tpm2-policy.h"
+
static const char hmac_alg[] = "hmac(sha1)";
static const char hash_alg[] = "sha1";
static struct tpm_chip *chip;
@@ -709,6 +711,7 @@ enum {
Opt_hash,
Opt_policydigest,
Opt_policyhandle,
+ Opt_policy,
};
static const match_table_t key_tokens = {
@@ -724,6 +727,7 @@ static const match_table_t key_tokens = {
{Opt_hash, "hash=%s"},
{Opt_policydigest, "policydigest=%s"},
{Opt_policyhandle, "policyhandle=%s"},
+ {Opt_policy, "policy=%s"},
{Opt_err, NULL}
};
@@ -855,6 +859,17 @@ static int getoptions(char *c, struct trusted_key_payload *pay,
return -EINVAL;
opt->policyhandle = handle;
break;
+
+ case Opt_policy:
+ if (pay->policies)
+ return -EINVAL;
+ if (!tpm2)
+ return -EINVAL;
+ res = tpm2_parse_policies(&pay->policies, args[0].from);
+ if (res)
+ return res;
+ break;
+
default:
return -EINVAL;
}
--
2.26.2
next prev parent reply other threads:[~2020-06-16 16:08 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-16 16:02 [PATCH v10 0/8] TPM 2.0 trusted keys with attached policy James Bottomley
2020-06-16 16:02 ` [PATCH v10 1/8] lib: add ASN.1 encoder James Bottomley
2020-06-16 16:02 ` [PATCH v10 2/8] oid_registry: Add TCG defined OIDS for TPM keys James Bottomley
2020-06-17 21:42 ` Jerry Snitselaar
2020-06-18 0:25 ` James Bottomley
2020-06-18 7:14 ` Jarkko Sakkinen
2020-06-18 19:22 ` James Bottomley
2020-06-22 22:04 ` Jarkko Sakkinen
2020-06-16 16:02 ` [PATCH v10 3/8] security: keys: trusted: fix TPM2 authorizations James Bottomley
2020-06-16 16:02 ` [PATCH v10 4/8] security: keys: trusted: use ASN.1 TPM2 key format for the blobs James Bottomley
2020-06-16 16:02 ` [PATCH v10 5/8] security: keys: trusted: Make sealed key properly interoperable James Bottomley
2020-06-17 23:46 ` Jarkko Sakkinen
2020-06-16 16:02 ` [PATCH v10 6/8] security: keys: trusted: add PCR policy to TPM2 keys James Bottomley
2020-06-17 23:44 ` Jarkko Sakkinen
2020-06-16 16:02 ` James Bottomley [this message]
2020-06-17 23:42 ` [PATCH v10 7/8] security: keys: trusted: add ability to specify arbitrary policy Jarkko Sakkinen
2020-06-18 0:27 ` James Bottomley
2020-06-18 7:12 ` Jarkko Sakkinen
2020-06-18 19:45 ` James Bottomley
2020-06-23 0:46 ` Jarkko Sakkinen
2020-06-16 16:02 ` [PATCH v10 8/8] security: keys: trusted: implement counter/timer policy James Bottomley
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