Re: [PATCH v1.5 4/5] keys: add new trusted key-type

From: David Howells
Date: Wed Dec 01 2010 - 13:52:01 EST


Mimi Zohar <zohar@xxxxxxxxxxxxxxxxxx> wrote:

> +static int TSS_sha1(const unsigned char *data, const unsigned int datalen,
> + unsigned char *digest)

You seem to have made a bunch of integer length parameters 'const'. Why? I
was suggesting making them size_t, not const.

I was suggesting making the data pointers const.

> + if (!ret)
> + TSS_rawhmac(digest, key, keylen, SHA1_DIGEST_SIZE,
> + paramdigest, TPM_NONCE_SIZE, h1,
> + TPM_NONCE_SIZE, h2, 1, &c, 0, 0);

TSS_rawhmac() can return an error.

> + ret = trusted_tpm_send(TPM_ANY_NUM, tb->data, sizeof tb->data);
> + memcpy(buf, tb->data + TPM_GETRANDOM_SIZE, len);

trusted_tpm_send() won't fail?

> +static int my_get_random(unsigned char *buf, int len)
> +{
> + struct tpm_buf *tb;
> + int ret;
> +
> + tb = kzalloc(sizeof *tb, GFP_KERNEL);
> + if (!tb)
> + return -ENOMEM;
> + ret = tpm_get_random(tb, buf, len);

Isn't is it pointless to use kzalloc() rather than kmalloc()?

> + my_get_random(hash, SHA1_DIGEST_SIZE);
> + return tpm_pcr_extend(TPM_ANY_NUM, pcrnum, hash) ? -EINVAL : 0;

my_get_random() won't fail?

> + ret = TSS_rawhmac(s->secret, key, SHA1_DIGEST_SIZE, TPM_NONCE_SIZE,
> + enonce, TPM_NONCE_SIZE, ononce, 0, 0);
> + return ret;

These can be merged.

> +static int oiap(struct tpm_buf *tb, uint32_t *handle, unsigned char *nonce)
> +{
> + int ret;
> +
> + INIT_BUF(tb);
> + store16(tb, TPM_TAG_RQU_COMMAND);
> + store32(tb, TPM_OIAP_SIZE);
> + store32(tb, TPM_ORD_OIAP);
> + ret = trusted_tpm_send(TPM_ANY_NUM, tb->data, MAX_BUF_SIZE);
> + if (ret < 0)
> + return ret;
> +
> + *handle = LOAD32(tb->data, TPM_DATA_OFFSET);
> + memcpy(nonce, &tb->data[TPM_DATA_OFFSET + sizeof(uint32_t)],
> + TPM_NONCE_SIZE);
> + return ret;
> +}

If you don't need to return ret specifically, returning 0 would be more
efficient.

> + ret = TSS_checkhmac1(tb->data, ordinal, td->nonceodd, sess.secret,
> + SHA1_DIGEST_SIZE, storedsize, TPM_DATA_OFFSET, 0,
> + 0);
> +
> + /* copy the returned blob to caller */
> + memcpy(blob, tb->data + TPM_DATA_OFFSET, storedsize);
> + *bloblen = storedsize;

Don't do that if TSS_checkhmac1() fails.

> + TSS_authhmac(authdata1, keyauth, TPM_NONCE_SIZE,
> + enonce1, nonceodd, cont, sizeof(uint32_t),
> + &ordinal, bloblen, blob, 0, 0);

TSS_authhmac() is called several times without checking for errors.

> + ret = TSS_checkhmac2(tb->data, ordinal, nonceodd,
> + keyauth, SHA1_DIGEST_SIZE,
> + blobauth, SHA1_DIGEST_SIZE,
> + sizeof(uint32_t), TPM_DATA_OFFSET,
> + *datalen, TPM_DATA_OFFSET + sizeof(uint32_t), 0,
> + 0);
> + if (ret < 0)
> + pr_info("trusted_key: TSS_checkhmac2 failed (%d)\n", ret);
> + memcpy(data, tb->data + TPM_DATA_OFFSET + sizeof(uint32_t), *datalen);
> + return ret;

Don't do the memcpy() if TSS_checkhmac2() fails.

> + ret = tpm_unseal(tb, o->keyhandle, o->keyauth, p->blob, p->blob_len,
> + o->blobauth, p->key, &p->key_len);
> + /* pull migratable flag out of sealed key */
> + p->migratable = p->key[--p->key_len];

Don't do that if tpm_unseal() fails.

> +static const match_table_t key_tokens = {
> + {Opt_new, "new"},
> + {Opt_load, "load"},
> + {Opt_update, "update"},
> + {Opt_keyhandle, "keyhandle=%s"},
> + {Opt_keyauth, "keyauth=%s"},
> + {Opt_blobauth, "blobauth=%s"},
> + {Opt_pcrinfo, "pcrinfo=%s"},
> + {Opt_pcrlock, "pcrlock=%s"},
> + {Opt_migratable, "migratable=%s"},
> + {Opt_err, NULL}

Spaces after { and before }. I'd also suggest using tabs to align the strings
vertically, but that's up to you.

> + p = kzalloc(sizeof *p, GFP_KERNEL);
> +
> + /* migratable by default */
> + p->migratable = 1;

NAK! p might be NULL.

David
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