Commit c78719203fc6 ("KEYS: trusted: allow trusted.ko to initialize w/o a
TPM") allows the trusted module to be loaded even a TPM is not found to
avoid module dependency problems.
However, trusted module initialization can still fail if the TPM is
inactive or deactivated. This patch ignores tpm_get_random() errors in
init_digests() and returns -EFAULT in pcrlock() if the TPM didn't return
random data.
Signed-off-by: Roberto Sassu <[email protected]>
---
security/keys/trusted.c | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)
diff --git a/security/keys/trusted.c b/security/keys/trusted.c
index 9a94672e7adc..34f04ffcf2e5 100644
--- a/security/keys/trusted.c
+++ b/security/keys/trusted.c
@@ -389,6 +389,10 @@ static int pcrlock(const int pcrnum)
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
+ /* This happens if the TPM didn't return random data */
+ if (!digests)
+ return -EFAULT;
+
return tpm_pcr_extend(chip, pcrnum, digests) ? -EINVAL : 0;
}
@@ -1233,10 +1237,8 @@ static int __init init_digests(void)
int i;
ret = tpm_get_random(chip, digest, TPM_MAX_DIGEST_SIZE);
- if (ret < 0)
- return ret;
- if (ret < TPM_MAX_DIGEST_SIZE)
- return -EFAULT;
+ if (ret < 0 || ret < TPM_MAX_DIGEST_SIZE)
+ return 0;
digests = kcalloc(chip->nr_allocated_banks, sizeof(*digests),
GFP_KERNEL);
--
2.17.1
On 2019-08-02 17:07:33, Roberto Sassu wrote:
> Commit c78719203fc6 ("KEYS: trusted: allow trusted.ko to initialize w/o a
> TPM") allows the trusted module to be loaded even a TPM is not found to
^ if
> avoid module dependency problems.
>
> However, trusted module initialization can still fail if the TPM is
> inactive or deactivated. This patch ignores tpm_get_random() errors in
> init_digests() and returns -EFAULT in pcrlock() if the TPM didn't return
> random data.
>
> Signed-off-by: Roberto Sassu <[email protected]>
The code changes look correct to me.
Reviewed-by: Tyler Hicks <[email protected]>
For whoever takes this patch through their tree, I think that adding the
following Fixes tag would be useful (as well as cc'ing stable):
Fixes: 240730437deb ("KEYS: trusted: explicitly use tpm_chip structure...")
I think it is also worth leaving a short note, in the commit message,
for backporters that commit 782779b60faa ("tpm: Actually fail on TPM
errors during "get random"") should be included with any backports of
this patch.
Thanks!
Tyler
> ---
> security/keys/trusted.c | 10 ++++++----
> 1 file changed, 6 insertions(+), 4 deletions(-)
>
> diff --git a/security/keys/trusted.c b/security/keys/trusted.c
> index 9a94672e7adc..34f04ffcf2e5 100644
> --- a/security/keys/trusted.c
> +++ b/security/keys/trusted.c
> @@ -389,6 +389,10 @@ static int pcrlock(const int pcrnum)
> if (!capable(CAP_SYS_ADMIN))
> return -EPERM;
>
> + /* This happens if the TPM didn't return random data */
> + if (!digests)
> + return -EFAULT;
> +
> return tpm_pcr_extend(chip, pcrnum, digests) ? -EINVAL : 0;
> }
>
> @@ -1233,10 +1237,8 @@ static int __init init_digests(void)
> int i;
>
> ret = tpm_get_random(chip, digest, TPM_MAX_DIGEST_SIZE);
> - if (ret < 0)
> - return ret;
> - if (ret < TPM_MAX_DIGEST_SIZE)
> - return -EFAULT;
> + if (ret < 0 || ret < TPM_MAX_DIGEST_SIZE)
> + return 0;
>
> digests = kcalloc(chip->nr_allocated_banks, sizeof(*digests),
> GFP_KERNEL);
> --
> 2.17.1
>
On 8/2/2019 5:30 PM, Tyler Hicks wrote:
> On 2019-08-02 17:07:33, Roberto Sassu wrote:
>> Commit c78719203fc6 ("KEYS: trusted: allow trusted.ko to initialize w/o a
>> TPM") allows the trusted module to be loaded even a TPM is not found to
> ^ if
>
>> avoid module dependency problems.
>>
>> However, trusted module initialization can still fail if the TPM is
>> inactive or deactivated. This patch ignores tpm_get_random() errors in
>> init_digests() and returns -EFAULT in pcrlock() if the TPM didn't return
>> random data.
>>
>> Signed-off-by: Roberto Sassu <[email protected]>
>
> The code changes look correct to me.
>
> Reviewed-by: Tyler Hicks <[email protected]>
>
> For whoever takes this patch through their tree, I think that adding the
> following Fixes tag would be useful (as well as cc'ing stable):
>
> Fixes: 240730437deb ("KEYS: trusted: explicitly use tpm_chip structure...")
>
> I think it is also worth leaving a short note, in the commit message,
> for backporters that commit 782779b60faa ("tpm: Actually fail on TPM
> errors during "get random"") should be included with any backports of
> this patch.
Right, thanks. I wait for Jarkko's comments and I add both the Fixes tag
and the short note in the next version of the patch.
Roberto
--
HUAWEI TECHNOLOGIES Duesseldorf GmbH, HRB 56063
Managing Director: Li Peng, Li Jian, Shi Yanli
On 8/2/2019 5:34 PM, Roberto Sassu wrote:
> On 8/2/2019 5:30 PM, Tyler Hicks wrote:
>> On 2019-08-02 17:07:33, Roberto Sassu wrote:
>>> Commit c78719203fc6 ("KEYS: trusted: allow trusted.ko to initialize
>>> w/o a
>>> TPM") allows the trusted module to be loaded even a TPM is not found to
>> ^ if
>>
>>> avoid module dependency problems.
>>>
>>> However, trusted module initialization can still fail if the TPM is
>>> inactive or deactivated. This patch ignores tpm_get_random() errors in
>>> init_digests() and returns -EFAULT in pcrlock() if the TPM didn't return
>>> random data.
>>>
>>> Signed-off-by: Roberto Sassu <[email protected]>
>>
>> The code changes look correct to me.
>>
>> Reviewed-by: Tyler Hicks <[email protected]>
>>
>> For whoever takes this patch through their tree, I think that adding the
>> following Fixes tag would be useful (as well as cc'ing stable):
>>
>> Fixes: 240730437deb ("KEYS: trusted: explicitly use tpm_chip
>> structure...")
>>
>> I think it is also worth leaving a short note, in the commit message,
>> for backporters that commit 782779b60faa ("tpm: Actually fail on TPM
>> errors during "get random"") should be included with any backports of
>> this patch.
>
> Right, thanks. I wait for Jarkko's comments and I add both the Fixes tag
> and the short note in the next version of the patch.
Uhm, I was thinking that maybe it is not necessary to mention commit
782779b60faa. This patch would still return 0 even if that commit is not
backported (TPM_ERR_DISABLED < TPM_MAX_DIGEST_SIZE).
Roberto
--
HUAWEI TECHNOLOGIES Duesseldorf GmbH, HRB 56063
Managing Director: Li Peng, Li Jian, Shi Yanli
On 2019-08-02 18:11:09, Roberto Sassu wrote:
> On 8/2/2019 5:34 PM, Roberto Sassu wrote:
> > On 8/2/2019 5:30 PM, Tyler Hicks wrote:
> > > On 2019-08-02 17:07:33, Roberto Sassu wrote:
> > > > Commit c78719203fc6 ("KEYS: trusted: allow trusted.ko to
> > > > initialize w/o a
> > > > TPM") allows the trusted module to be loaded even a TPM is not found to
> > > ??????????????????????????????????????????????????? ^ if
> > >
> > > > avoid module dependency problems.
> > > >
> > > > However, trusted module initialization can still fail if the TPM is
> > > > inactive or deactivated. This patch ignores tpm_get_random() errors in
> > > > init_digests() and returns -EFAULT in pcrlock() if the TPM didn't return
> > > > random data.
> > > >
> > > > Signed-off-by: Roberto Sassu <[email protected]>
> > >
> > > The code changes look correct to me.
> > >
> > > ?? Reviewed-by: Tyler Hicks <[email protected]>
> > >
> > > For whoever takes this patch through their tree, I think that adding the
> > > following Fixes tag would be useful (as well as cc'ing stable):
> > >
> > > ?? Fixes: 240730437deb ("KEYS: trusted: explicitly use tpm_chip
> > > structure...")
> > >
> > > I think it is also worth leaving a short note, in the commit message,
> > > for backporters that commit 782779b60faa ("tpm: Actually fail on TPM
> > > errors during "get random"") should be included with any backports of
> > > this patch.
> >
> > Right, thanks. I wait for Jarkko's comments and I add both the Fixes tag
> > and the short note in the next version of the patch.
>
> Uhm, I was thinking that maybe it is not necessary to mention commit
> 782779b60faa. This patch would still return 0 even if that commit is not
> backported (TPM_ERR_DISABLED < TPM_MAX_DIGEST_SIZE).
The commit message for 782779b60faa shows 379 being returned when
attempting to get random:
[ 18.092103] tpm tpm0: A TPM error (379) occurred attempting get random
I don't know enough about TPM chips to know how common that is...
Tyler
>
> Roberto
>
> --
> HUAWEI TECHNOLOGIES Duesseldorf GmbH, HRB 56063
> Managing Director: Li Peng, Li Jian, Shi Yanli