@@ -70,6 +70,9 @@ Usage::
hash= hash algorithm name as a string. For TPM 1.x the only
allowed value is sha1. For TPM 2.x the allowed values
are sha1, sha256, sha384, sha512 and sm3-256.
+ 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.
@@ -162,6 +165,19 @@ 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`"
@@ -338,3 +338,49 @@ 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;
+}
@@ -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);
@@ -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;
@@ -706,7 +708,7 @@ enum {
Opt_new, Opt_load, Opt_update,
Opt_keyhandle, Opt_keyauth, Opt_blobauth,
Opt_pcrinfo, Opt_pcrlock, Opt_migratable,
- Opt_hash,
+ Opt_hash, Opt_policy,
};
static const match_table_t key_tokens = {
@@ -720,6 +722,7 @@ static const match_table_t key_tokens = {
{Opt_pcrlock, "pcrlock=%s"},
{Opt_migratable, "migratable=%s"},
{Opt_hash, "hash=%s"},
+ {Opt_policy, "policy=%s"},
{Opt_err, NULL}
};
@@ -809,6 +812,15 @@ static int getoptions(char *c, struct trusted_key_payload *pay,
return -EINVAL;
}
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;
}
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> --- Documentation/security/keys/trusted-encrypted.rst | 16 ++++++++ security/keys/trusted-keys/tpm2-policy.c | 46 +++++++++++++++++++++++ security/keys/trusted-keys/tpm2-policy.h | 1 + security/keys/trusted-keys/trusted_tpm1.c | 14 ++++++- 4 files changed, 76 insertions(+), 1 deletion(-)