linux-kernel - Re: [PATCH v9 3/8] KEYS: trusted: Replace a redundant instance of tpm2_hash

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Message-ID: <aSlvCROaUqwZ244Z@earth.li>
Date: Fri, 28 Nov 2025 09:44:41 +0000
From: Jonathan McDowell <noodles@...th.li>
To: Jarkko Sakkinen <jarkko@...nel.org>
Cc: linux-integrity@...r.kernel.org, ross.philipson@...cle.com,
	Stefano Garzarella <sgarzare@...hat.com>,
	Peter Huewe <peterhuewe@....de>, Jason Gunthorpe <jgg@...pe.ca>,
	James Bottomley <James.Bottomley@...senpartnership.com>,
	Mimi Zohar <zohar@...ux.ibm.com>,
	David Howells <dhowells@...hat.com>,
	Paul Moore <paul@...l-moore.com>, James Morris <jmorris@...ei.org>,
	"Serge E. Hallyn" <serge@...lyn.com>, linux-kernel@...r.kernel.org,
	keyrings@...r.kernel.org, linux-security-module@...r.kernel.org
Subject: Re: [PATCH v9 3/8] KEYS: trusted: Replace a redundant instance of
 tpm2_hash_map

On Fri, Nov 28, 2025 at 04:53:55AM +0200, Jarkko Sakkinen wrote:
>'trusted_tpm2' duplicates 'tpm2_hash_map' originally part of the TPN
>driver, which is suboptimal.
>
>Implement and export `tpm2_find_hash_alg()` in the driver, and substitute
>the redundant code in 'trusted_tpm2' with a call to the new function.
>
>Signed-off-by: Jarkko Sakkinen <jarkko@...nel.org>

Reviewed-by: Jonathan McDowell <noodles@...a.com>

>---
>v9:
>- Improved the commit message a bit.
>v8:
>- Remove spurious tpm2_alg_to_crypto_id.
>- Check return value of tpm2_find_hash_alg correctly in trusted_tpm2.c
>  i.e, fail on "hash_alg < 0". Trusted keys were tested but I had my
>  test harness misconfigured. I bisected the failure to this patch.
>- The diff was not exactly minimal. Further optimize it.
>v7:
>- A new patch.
>---
> drivers/char/tpm/tpm2-cmd.c               | 14 +++++++++++++-
> include/linux/tpm.h                       |  1 +
> security/keys/trusted-keys/trusted_tpm2.c | 23 ++++-------------------
> 3 files changed, 18 insertions(+), 20 deletions(-)
>
>diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c
>index e298194883e8..a121c518ff6f 100644
>--- a/drivers/char/tpm/tpm2-cmd.c
>+++ b/drivers/char/tpm/tpm2-cmd.c
>@@ -18,7 +18,7 @@ static bool disable_pcr_integrity;
> module_param(disable_pcr_integrity, bool, 0444);
> MODULE_PARM_DESC(disable_pcr_integrity, "Disable integrity protection of TPM2_PCR_Extend");
>
>-static struct tpm2_hash tpm2_hash_map[] = {
>+struct tpm2_hash tpm2_hash_map[] = {
> 	{HASH_ALGO_SHA1, TPM_ALG_SHA1},
> 	{HASH_ALGO_SHA256, TPM_ALG_SHA256},
> 	{HASH_ALGO_SHA384, TPM_ALG_SHA384},
>@@ -26,6 +26,18 @@ static struct tpm2_hash tpm2_hash_map[] = {
> 	{HASH_ALGO_SM3_256, TPM_ALG_SM3_256},
> };
>
>+int tpm2_find_hash_alg(unsigned int crypto_id)
>+{
>+	int i;
>+
>+	for (i = 0; i < ARRAY_SIZE(tpm2_hash_map); i++)
>+		if (crypto_id == tpm2_hash_map[i].crypto_id)
>+			return tpm2_hash_map[i].tpm_id;
>+
>+	return -EINVAL;
>+}
>+EXPORT_SYMBOL_GPL(tpm2_find_hash_alg);
>+
> int tpm2_get_timeouts(struct tpm_chip *chip)
> {
> 	chip->timeout_a = msecs_to_jiffies(TPM2_TIMEOUT_A);
>diff --git a/include/linux/tpm.h b/include/linux/tpm.h
>index 973458a38250..cbd3a70c0378 100644
>--- a/include/linux/tpm.h
>+++ b/include/linux/tpm.h
>@@ -477,6 +477,7 @@ extern int tpm_pcr_extend(struct tpm_chip *chip, u32 pcr_idx,
> extern int tpm_get_random(struct tpm_chip *chip, u8 *data, size_t max);
> extern struct tpm_chip *tpm_default_chip(void);
> void tpm2_flush_context(struct tpm_chip *chip, u32 handle);
>+int tpm2_find_hash_alg(unsigned int crypto_id);
>
> static inline void tpm_buf_append_empty_auth(struct tpm_buf *buf, u32 handle)
> {
>diff --git a/security/keys/trusted-keys/trusted_tpm2.c b/security/keys/trusted-keys/trusted_tpm2.c
>index c414a7006d78..4467e880ebd5 100644
>--- a/security/keys/trusted-keys/trusted_tpm2.c
>+++ b/security/keys/trusted-keys/trusted_tpm2.c
>@@ -18,14 +18,6 @@
>
> #include "tpm2key.asn1.h"
>
>-static struct tpm2_hash tpm2_hash_map[] = {
>-	{HASH_ALGO_SHA1, TPM_ALG_SHA1},
>-	{HASH_ALGO_SHA256, TPM_ALG_SHA256},
>-	{HASH_ALGO_SHA384, TPM_ALG_SHA384},
>-	{HASH_ALGO_SHA512, TPM_ALG_SHA512},
>-	{HASH_ALGO_SM3_256, TPM_ALG_SM3_256},
>-};
>-
> static u32 tpm2key_oid[] = { 2, 23, 133, 10, 1, 5 };
>
> static int tpm2_key_encode(struct trusted_key_payload *payload,
>@@ -244,20 +236,13 @@ int tpm2_seal_trusted(struct tpm_chip *chip,
> 	off_t offset = TPM_HEADER_SIZE;
> 	struct tpm_buf buf, sized;
> 	int blob_len = 0;
>-	u32 hash;
>+	int hash;
> 	u32 flags;
>-	int i;
> 	int rc;
>
>-	for (i = 0; i < ARRAY_SIZE(tpm2_hash_map); i++) {
>-		if (options->hash == tpm2_hash_map[i].crypto_id) {
>-			hash = tpm2_hash_map[i].tpm_id;
>-			break;
>-		}
>-	}
>-
>-	if (i == ARRAY_SIZE(tpm2_hash_map))
>-		return -EINVAL;
>+	hash = tpm2_find_hash_alg(options->hash);
>+	if (hash < 0)
>+		return hash;
>
> 	if (!options->keyhandle)
> 		return -EINVAL;
>-- 
>2.52.0
>

J.

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