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: Jarkko Sakkinen <jarkko@xxxxxxxxxx> --- v3 [2023-11-21]: A boundary error check as response for the feeedback from Mario Limenciello: https://lore.kernel.org/linux-integrity/3f9086f6-935f-48a7-889b-c71398422fa1@xxxxxxx/ v2: Use tpm_buf_read_* --- security/keys/trusted-keys/trusted_tpm2.c | 54 +++++++++++++---------- 1 file changed, 31 insertions(+), 23 deletions(-) diff --git a/security/keys/trusted-keys/trusted_tpm2.c b/security/keys/trusted-keys/trusted_tpm2.c index bc700f85f80b..97b1dfca2dba 100644 --- 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) { -- 2.42.1
