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

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Date:	Wed, 01 Dec 2010 16:18:00 -0500
From:	David Safford <safford@...son.ibm.com>
To:	David Howells <dhowells@...hat.com>
Cc:	Mimi Zohar <zohar@...ux.vnet.ibm.com>,
	linux-kernel@...r.kernel.org,
	linux-security-module@...r.kernel.org, keyrings@...ux-nfs.org,
	linux-crypto@...r.kernel.org,
	Jason Gunthorpe <jgunthorpe@...idianresearch.com>,
	James Morris <jmorris@...ei.org>,
	Rajiv Andrade <srajiv@...ux.vnet.ibm.com>,
	Mimi Zohar <zohar@...ibm.com>
Subject: Re: [PATCH v1.5 4/5] keys: add new trusted key-type

On Wed, 2010-12-01 at 17:48 +0000, David Howells wrote:
> Mimi Zohar <zohar@...ux.vnet.ibm.com> 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.

I think all the data pointers that are const have been fixed.
Will clean up the ints with size_t and not const as appropriate.

> > +	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.

will fix.

> > +	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?

will fix.

> > +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()?

correct - zero not needed here.

> > +	my_get_random(hash, SHA1_DIGEST_SIZE);
> > +	return tpm_pcr_extend(TPM_ANY_NUM, pcrnum, hash) ? -EINVAL : 0;
> 
> my_get_random() won't fail?

will fix.

> > +	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.

will merge.

> > +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.

right - this can be return 0;

> > +	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.

will fix.

> > +	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.

will fix.

> > +	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.

will fix.

> > +	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.

will fix.

> > +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.

Lindent takes the spaces out, CodingStyle doesn't say, and most similar
examples in the kernel leave them out.

> > +	p = kzalloc(sizeof *p, GFP_KERNEL);
> > +
> > +	/* migratable by default */
> > +	p->migratable = 1;
> 
> NAK!  p might be NULL.

yikes! will fix.

dave

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