KEYS: trusted: tpm2: Use struct tpm_buf for sized buffers

Take advantage of the new sized buffer (TPM2B) mode of struct tpm_buf in
tpm2_seal_trusted(). This allows to add robustness to the command
construction without requiring to calculate buffer sizes manually.

Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
Reviewed-by: Stefan Berger <stefanb@linux.ibm.com>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Tested-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>

diff --git a/security/keys/trusted-keys/trusted_tpm2.c b/security/keys/trusted-keys/trusted_tpm2.c
index bc700f85f80be73e587522aab8df7b81f6f830c1..97b1dfca2dba54ed5c174373faf4b1415df6d495 100644 (file)
--- a/security/keys/trusted-keys/trusted_tpm2.c
+++ b/security/keys/trusted-keys/trusted_tpm2.c
@@ -228,8 +228,9 @@ int tpm2_seal_trusted(struct tpm_chip *chip,
                      struct trusted_key_payload *payload,
                      struct trusted_key_options *options)
 {
+       off_t offset = TPM_HEADER_SIZE;
+       struct tpm_buf buf, sized;
        int blob_len = 0;
-       struct tpm_buf buf;
        u32 hash;
        u32 flags;
        int i;
@@ -258,6 +259,14 @@ int tpm2_seal_trusted(struct tpm_chip *chip,
                return rc;
        }
 
+       rc = tpm_buf_init_sized(&sized);
+       if (rc) {
+               tpm_buf_destroy(&buf);
+               tpm_put_ops(chip);
+               return rc;
+       }
+
+       tpm_buf_reset(&buf, TPM2_ST_SESSIONS, TPM2_CC_CREATE);
        tpm_buf_append_u32(&buf, options->keyhandle);
        tpm2_buf_append_auth(&buf, TPM2_RS_PW,
                             NULL /* nonce */, 0,
@@ -266,36 +275,36 @@ int tpm2_seal_trusted(struct tpm_chip *chip,
                             TPM_DIGEST_SIZE);
 
        /* sensitive */
-       tpm_buf_append_u16(&buf, 4 + options->blobauth_len + payload->key_len);
+       tpm_buf_append_u16(&sized, options->blobauth_len);
 
-       tpm_buf_append_u16(&buf, options->blobauth_len);
        if (options->blobauth_len)
-               tpm_buf_append(&buf, options->blobauth, options->blobauth_len);
+               tpm_buf_append(&sized, options->blobauth, options->blobauth_len);
 
-       tpm_buf_append_u16(&buf, payload->key_len);
-       tpm_buf_append(&buf, payload->key, payload->key_len);
+       tpm_buf_append_u16(&sized, payload->key_len);
+       tpm_buf_append(&sized, payload->key, payload->key_len);
+       tpm_buf_append(&buf, sized.data, sized.length);
 
        /* public */
-       tpm_buf_append_u16(&buf, 14 + options->policydigest_len);
-       tpm_buf_append_u16(&buf, TPM_ALG_KEYEDHASH);
-       tpm_buf_append_u16(&buf, hash);
+       tpm_buf_reset_sized(&sized);
+       tpm_buf_append_u16(&sized, TPM_ALG_KEYEDHASH);
+       tpm_buf_append_u16(&sized, hash);
 
        /* key properties */
        flags = 0;
        flags |= options->policydigest_len ? 0 : TPM2_OA_USER_WITH_AUTH;
-       flags |= payload->migratable ? 0 : (TPM2_OA_FIXED_TPM |
-                                           TPM2_OA_FIXED_PARENT);
-       tpm_buf_append_u32(&buf, flags);
+       flags |= payload->migratable ? 0 : (TPM2_OA_FIXED_TPM | TPM2_OA_FIXED_PARENT);
+       tpm_buf_append_u32(&sized, flags);
 
        /* policy */
-       tpm_buf_append_u16(&buf, options->policydigest_len);
+       tpm_buf_append_u16(&sized, options->policydigest_len);
        if (options->policydigest_len)
-               tpm_buf_append(&buf, options->policydigest,
-                              options->policydigest_len);
+               tpm_buf_append(&sized, options->policydigest, options->policydigest_len);
 
        /* public parameters */
-       tpm_buf_append_u16(&buf, TPM_ALG_NULL);
-       tpm_buf_append_u16(&buf, 0);
+       tpm_buf_append_u16(&sized, TPM_ALG_NULL);
+       tpm_buf_append_u16(&sized, 0);
+
+       tpm_buf_append(&buf, sized.data, sized.length);
 
        /* outside info */
        tpm_buf_append_u16(&buf, 0);
@@ -312,21 +321,20 @@ int tpm2_seal_trusted(struct tpm_chip *chip,
        if (rc)
                goto out;
 
-       blob_len = be32_to_cpup((__be32 *) &buf.data[TPM_HEADER_SIZE]);
-       if (blob_len > MAX_BLOB_SIZE) {
+       blob_len = tpm_buf_read_u32(&buf, &offset);
+       if (blob_len > MAX_BLOB_SIZE || buf.flags & TPM_BUF_BOUNDARY_ERROR) {
                rc = -E2BIG;
                goto out;
        }
-       if (tpm_buf_length(&buf) < TPM_HEADER_SIZE + 4 + blob_len) {
+       if (buf.length - offset < blob_len) {
                rc = -EFAULT;
                goto out;
        }
 
-       blob_len = tpm2_key_encode(payload, options,
-                                  &buf.data[TPM_HEADER_SIZE + 4],
-                                  blob_len);
+       blob_len = tpm2_key_encode(payload, options, &buf.data[offset], blob_len);
 
 out:
+       tpm_buf_destroy(&sized);
        tpm_buf_destroy(&buf);
 
        if (rc > 0) {