diff mbox series

[1/2] KEYS: trusted: Fix incorrect handling of tpm_get_random()

Message ID 20200928132405.68624-1-jarkko.sakkinen@linux.intel.com (mailing list archive)
State New
Headers show
Series [1/2] KEYS: trusted: Fix incorrect handling of tpm_get_random() | expand

Commit Message

Jarkko Sakkinen Sept. 28, 2020, 1:24 p.m. UTC
When tpm_get_random() was introduced, it defined the following API for the
return value:

1. A positive value tells how many bytes of random data was generated.
2. A negative value on error.

However, in the call sites the API was used incorrectly, i.e. as it would
only return negative values and otherwise zero. Returning he positive read
counts to the user space does not make any possible sense.

Fix this by returning -EIO when tpm_get_random() returns a positive value.

Fixes: 41ab999c80f1 ("tpm: Move tpm_get_random api into the TPM device driver")
Cc: Kent Yoder <key@linux.vnet.ibm.com>
Cc: David Howells <dhowells@redhat.com>
Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>
Cc: stable@vger.kernel.org
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
---
 security/keys/trusted-keys/trusted_tpm1.c | 19 +++++++++++++++++--
 1 file changed, 17 insertions(+), 2 deletions(-)

Comments

Jarkko Sakkinen Sept. 28, 2020, 3:24 p.m. UTC | #1
On Mon, Sep 28, 2020 at 04:24:04PM +0300, Jarkko Sakkinen wrote:
> When tpm_get_random() was introduced, it defined the following API for the
> return value:
> 
> 1. A positive value tells how many bytes of random data was generated.
> 2. A negative value on error.
> 
> However, in the call sites the API was used incorrectly, i.e. as it would
> only return negative values and otherwise zero. Returning he positive read
> counts to the user space does not make any possible sense.
> 
> Fix this by returning -EIO when tpm_get_random() returns a positive value.
> 
> Fixes: 41ab999c80f1 ("tpm: Move tpm_get_random api into the TPM device driver")
> Cc: Kent Yoder <key@linux.vnet.ibm.com>
> Cc: David Howells <dhowells@redhat.com>
> Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>
> Cc: stable@vger.kernel.org
> Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
> ---
>  security/keys/trusted-keys/trusted_tpm1.c | 19 +++++++++++++++++--
>  1 file changed, 17 insertions(+), 2 deletions(-)
> 
> diff --git a/security/keys/trusted-keys/trusted_tpm1.c b/security/keys/trusted-keys/trusted_tpm1.c
> index b9fe02e5f84f..0f2e893c6b5f 100644
> --- a/security/keys/trusted-keys/trusted_tpm1.c
> +++ b/security/keys/trusted-keys/trusted_tpm1.c
> @@ -403,9 +403,12 @@ static int osap(struct tpm_buf *tb, struct osapsess *s,
>  	int ret;
>  
>  	ret = tpm_get_random(chip, ononce, TPM_NONCE_SIZE);
> -	if (ret != TPM_NONCE_SIZE)
> +	if (ret < 0)
>  		return ret;
>  
> +	if (ret != TPM_NONCE_SIZE)
> +		return -EIO;
> +
>  	tpm_buf_reset(tb, TPM_TAG_RQU_COMMAND, TPM_ORD_OSAP);
>  	tpm_buf_append_u16(tb, type);
>  	tpm_buf_append_u32(tb, handle);
> @@ -496,8 +499,12 @@ static int tpm_seal(struct tpm_buf *tb, uint16_t keytype,
>  		goto out;
>  
>  	ret = tpm_get_random(chip, td->nonceodd, TPM_NONCE_SIZE);
> +	if (ret < 0)
> +		return ret;
> +
>  	if (ret != TPM_NONCE_SIZE)
> -		goto out;
> +		return -EIO;
> +
>  	ordinal = htonl(TPM_ORD_SEAL);
>  	datsize = htonl(datalen);
>  	pcrsize = htonl(pcrinfosize);
> @@ -601,6 +608,9 @@ static int tpm_unseal(struct tpm_buf *tb,
>  
>  	ordinal = htonl(TPM_ORD_UNSEAL);
>  	ret = tpm_get_random(chip, nonceodd, TPM_NONCE_SIZE);
> +	if (ret < 0)
> +		return -EIO;
> +
>  	if (ret != TPM_NONCE_SIZE) {
>  		pr_info("trusted_key: tpm_get_random failed (%d)\n", ret);
>  		return ret;
> @@ -1013,6 +1023,11 @@ static int trusted_instantiate(struct key *key,
>  	case Opt_new:
>  		key_len = payload->key_len;
>  		ret = tpm_get_random(chip, payload->key, key_len);
> +		if (ret < 0) {
> +			ret = -EIO;
> +			goto out;
> +		}
> +
>  		if (ret != key_len) {
>  			pr_info("trusted_key: key_create failed (%d)\n", ret);
>  			goto out;

Ugh. I'll send an update (was not the final version, had unstaged
changes).

/Jarkko
diff mbox series

Patch

diff --git a/security/keys/trusted-keys/trusted_tpm1.c b/security/keys/trusted-keys/trusted_tpm1.c
index b9fe02e5f84f..0f2e893c6b5f 100644
--- a/security/keys/trusted-keys/trusted_tpm1.c
+++ b/security/keys/trusted-keys/trusted_tpm1.c
@@ -403,9 +403,12 @@  static int osap(struct tpm_buf *tb, struct osapsess *s,
 	int ret;
 
 	ret = tpm_get_random(chip, ononce, TPM_NONCE_SIZE);
-	if (ret != TPM_NONCE_SIZE)
+	if (ret < 0)
 		return ret;
 
+	if (ret != TPM_NONCE_SIZE)
+		return -EIO;
+
 	tpm_buf_reset(tb, TPM_TAG_RQU_COMMAND, TPM_ORD_OSAP);
 	tpm_buf_append_u16(tb, type);
 	tpm_buf_append_u32(tb, handle);
@@ -496,8 +499,12 @@  static int tpm_seal(struct tpm_buf *tb, uint16_t keytype,
 		goto out;
 
 	ret = tpm_get_random(chip, td->nonceodd, TPM_NONCE_SIZE);
+	if (ret < 0)
+		return ret;
+
 	if (ret != TPM_NONCE_SIZE)
-		goto out;
+		return -EIO;
+
 	ordinal = htonl(TPM_ORD_SEAL);
 	datsize = htonl(datalen);
 	pcrsize = htonl(pcrinfosize);
@@ -601,6 +608,9 @@  static int tpm_unseal(struct tpm_buf *tb,
 
 	ordinal = htonl(TPM_ORD_UNSEAL);
 	ret = tpm_get_random(chip, nonceodd, TPM_NONCE_SIZE);
+	if (ret < 0)
+		return -EIO;
+
 	if (ret != TPM_NONCE_SIZE) {
 		pr_info("trusted_key: tpm_get_random failed (%d)\n", ret);
 		return ret;
@@ -1013,6 +1023,11 @@  static int trusted_instantiate(struct key *key,
 	case Opt_new:
 		key_len = payload->key_len;
 		ret = tpm_get_random(chip, payload->key, key_len);
+		if (ret < 0) {
+			ret = -EIO;
+			goto out;
+		}
+
 		if (ret != key_len) {
 			pr_info("trusted_key: key_create failed (%d)\n", ret);
 			goto out;