2021-02-11 20:00:41

by Nayna Jain

Subject: [PATCH 2/5] keys: generate self-signed module signing key using CSR

Loading a key on the IMA trusted keyring requires the key be signed
by an existing key on the builtin or secondary trusted keyring.
Creating a Certificate Signing Request (CSR) allows the certificate
to be self-signed or signed by a CA.

This patch generates a self-signed module signing key using CSR.

Signed-off-by: Nayna Jain <[email protected]>
---
Makefile | 3 ++-
certs/Makefile | 15 +++++++++++----
2 files changed, 13 insertions(+), 5 deletions(-)

diff --git a/Makefile b/Makefile
index af18aab6bbee..9c87fdd600d8 100644
--- a/Makefile
+++ b/Makefile
@@ -1473,7 +1473,8 @@ MRPROPER_FILES += include/config include/generated \
.config .config.old .version \
Module.symvers \
certs/signing_key.pem certs/signing_key.x509 \
- certs/x509.genkey \
+ certs/x509.genkey certs/signing_key.key \
+ certs/signing_key.crt certs/signing_key.csr \
vmlinux-gdb.py \
*.spec

diff --git a/certs/Makefile b/certs/Makefile
index f4c25b67aad9..b2be7eb413d3 100644
--- a/certs/Makefile
+++ b/certs/Makefile
@@ -60,11 +60,18 @@ $(obj)/signing_key.pem: $(obj)/x509.genkey
@$(kecho) "### needs to be run as root, and uses a hardware random"
@$(kecho) "### number generator if one is available."
@$(kecho) "###"
- $(Q)openssl req -new -nodes -utf8 -$(CONFIG_MODULE_SIG_HASH) -days 36500 \
- -batch -x509 -config $(obj)/x509.genkey \
- -outform PEM -out $(obj)/signing_key.pem \
- -keyout $(obj)/signing_key.pem \
+ $(Q)openssl req -new -nodes -utf8 \
+ -batch -config $(obj)/x509.genkey \
+ -outform PEM -out $(obj)/signing_key.csr \
+ -keyout $(obj)/signing_key.key -extensions myexts \
$($(quiet)redirect_openssl)
+ $(Q)openssl x509 -req -days 36500 -in $(obj)/signing_key.csr \
+ -outform PEM -out $(obj)/signing_key.crt \
+ -signkey $(obj)/signing_key.key \
+ -$(CONFIG_MODULE_SIG_HASH) -extensions myexts \
+ -extfile $(obj)/x509.genkey \
+ $($(quiet)redirect_openssl)
+ @cat $(obj)/signing_key.key $(obj)/signing_key.crt >> $(obj)/signing_key.pem
@$(kecho) "###"
@$(kecho) "### Key pair generated."
@$(kecho) "###"
--
2.18.1

2021-02-11 22:06:46

by Stefan Berger

Subject: Re: [PATCH 2/5] keys: generate self-signed module signing key using CSR

On 2/11/21 2:54 PM, Nayna Jain wrote:
> Loading a key on the IMA trusted keyring requires the key be signed
> by an existing key on the builtin or secondary trusted keyring.
> Creating a Certificate Signing Request (CSR) allows the certificate
> to be self-signed or signed by a CA.
>
> This patch generates a self-signed module signing key using CSR.
>
> Signed-off-by: Nayna Jain <[email protected]>
> ---
> Makefile | 3 ++-
> certs/Makefile | 15 +++++++++++----
> 2 files changed, 13 insertions(+), 5 deletions(-)
>
> diff --git a/Makefile b/Makefile
> index af18aab6bbee..9c87fdd600d8 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -1473,7 +1473,8 @@ MRPROPER_FILES += include/config include/generated \
> .config .config.old .version \
> Module.symvers \
> certs/signing_key.pem certs/signing_key.x509 \
> - certs/x509.genkey \
> + certs/x509.genkey certs/signing_key.key \
> + certs/signing_key.crt certs/signing_key.csr \
> vmlinux-gdb.py \
> *.spec
>
> diff --git a/certs/Makefile b/certs/Makefile
> index f4c25b67aad9..b2be7eb413d3 100644
> --- a/certs/Makefile
> +++ b/certs/Makefile
> @@ -60,11 +60,18 @@ $(obj)/signing_key.pem: $(obj)/x509.genkey
> @$(kecho) "### needs to be run as root, and uses a hardware random"
> @$(kecho) "### number generator if one is available."
> @$(kecho) "###"
> - $(Q)openssl req -new -nodes -utf8 -$(CONFIG_MODULE_SIG_HASH) -days 36500 \
> - -batch -x509 -config $(obj)/x509.genkey \
> - -outform PEM -out $(obj)/signing_key.pem \
> - -keyout $(obj)/signing_key.pem \
> + $(Q)openssl req -new -nodes -utf8 \
> + -batch -config $(obj)/x509.genkey \
> + -outform PEM -out $(obj)/signing_key.csr \
> + -keyout $(obj)/signing_key.key -extensions myexts \
> $($(quiet)redirect_openssl)
> + $(Q)openssl x509 -req -days 36500 -in $(obj)/signing_key.csr \
> + -outform PEM -out $(obj)/signing_key.crt \
> + -signkey $(obj)/signing_key.key \
> + -$(CONFIG_MODULE_SIG_HASH) -extensions myexts \
> + -extfile $(obj)/x509.genkey \
> + $($(quiet)redirect_openssl)
> + @cat $(obj)/signing_key.key $(obj)/signing_key.crt >> $(obj)/signing_key.pem


Could you not just rename signing_key.key to signing_key.pem (as it was
before) and that would be it? Why do you need the .crt in that pem bundle?

   Stefan

2021-02-12 23:52:11

by Jarkko Sakkinen

Subject: Re: [PATCH 2/5] keys: generate self-signed module signing key using CSR

On Thu, Feb 11, 2021 at 02:54:32PM -0500, Nayna Jain wrote:
> Loading a key on the IMA trusted keyring requires the key be signed
> by an existing key on the builtin or secondary trusted keyring.
> Creating a Certificate Signing Request (CSR) allows the certificate
> to be self-signed or signed by a CA.
>
> This patch generates a self-signed module signing key using CSR.

"Generate ..."

/Jarkko

>
> Signed-off-by: Nayna Jain <[email protected]>
> ---
> Makefile | 3 ++-
> certs/Makefile | 15 +++++++++++----
> 2 files changed, 13 insertions(+), 5 deletions(-)
>
> diff --git a/Makefile b/Makefile
> index af18aab6bbee..9c87fdd600d8 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -1473,7 +1473,8 @@ MRPROPER_FILES += include/config include/generated \
> .config .config.old .version \
> Module.symvers \
> certs/signing_key.pem certs/signing_key.x509 \
> - certs/x509.genkey \
> + certs/x509.genkey certs/signing_key.key \
> + certs/signing_key.crt certs/signing_key.csr \
> vmlinux-gdb.py \
> *.spec
>
> diff --git a/certs/Makefile b/certs/Makefile
> index f4c25b67aad9..b2be7eb413d3 100644
> --- a/certs/Makefile
> +++ b/certs/Makefile
> @@ -60,11 +60,18 @@ $(obj)/signing_key.pem: $(obj)/x509.genkey
> @$(kecho) "### needs to be run as root, and uses a hardware random"
> @$(kecho) "### number generator if one is available."
> @$(kecho) "###"
> - $(Q)openssl req -new -nodes -utf8 -$(CONFIG_MODULE_SIG_HASH) -days 36500 \
> - -batch -x509 -config $(obj)/x509.genkey \
> - -outform PEM -out $(obj)/signing_key.pem \
> - -keyout $(obj)/signing_key.pem \
> + $(Q)openssl req -new -nodes -utf8 \
> + -batch -config $(obj)/x509.genkey \
> + -outform PEM -out $(obj)/signing_key.csr \
> + -keyout $(obj)/signing_key.key -extensions myexts \
> $($(quiet)redirect_openssl)
> + $(Q)openssl x509 -req -days 36500 -in $(obj)/signing_key.csr \
> + -outform PEM -out $(obj)/signing_key.crt \
> + -signkey $(obj)/signing_key.key \
> + -$(CONFIG_MODULE_SIG_HASH) -extensions myexts \
> + -extfile $(obj)/x509.genkey \
> + $($(quiet)redirect_openssl)
> + @cat $(obj)/signing_key.key $(obj)/signing_key.crt >> $(obj)/signing_key.pem
> @$(kecho) "###"
> @$(kecho) "### Key pair generated."
> @$(kecho) "###"
> --
> 2.18.1
>
>

2021-02-18 22:07:27

by Nayna Jain

Subject: Re: [PATCH 2/5] keys: generate self-signed module signing key using CSR

On 2/11/21 5:01 PM, Stefan Berger wrote:
> On 2/11/21 2:54 PM, Nayna Jain wrote:
>> Loading a key on the IMA trusted keyring requires the key be signed
>> by an existing key on the builtin or secondary trusted keyring.
>> Creating a Certificate Signing Request (CSR) allows the certificate
>> to be self-signed or signed by a CA.
>>
>> This patch generates a self-signed module signing key using CSR.
>>
>> Signed-off-by: Nayna Jain <[email protected]>
>> ---
>>   Makefile       |  3 ++-
>>   certs/Makefile | 15 +++++++++++----
>>   2 files changed, 13 insertions(+), 5 deletions(-)
>>
>> diff --git a/Makefile b/Makefile
>> index af18aab6bbee..9c87fdd600d8 100644
>> --- a/Makefile
>> +++ b/Makefile
>> @@ -1473,7 +1473,8 @@ MRPROPER_FILES += include/config
>> include/generated          \
>>             .config .config.old .version \
>>             Module.symvers \
>>             certs/signing_key.pem certs/signing_key.x509 \
>> -          certs/x509.genkey \
>> +          certs/x509.genkey certs/signing_key.key \
>> +          certs/signing_key.crt certs/signing_key.csr \
>>             vmlinux-gdb.py \
>>             *.spec
>>   diff --git a/certs/Makefile b/certs/Makefile
>> index f4c25b67aad9..b2be7eb413d3 100644
>> --- a/certs/Makefile
>> +++ b/certs/Makefile
>> @@ -60,11 +60,18 @@ $(obj)/signing_key.pem: $(obj)/x509.genkey
>>       @$(kecho) "### needs to be run as root, and uses a hardware
>> random"
>>       @$(kecho) "### number generator if one is available."
>>       @$(kecho) "###"
>> -    $(Q)openssl req -new -nodes -utf8 -$(CONFIG_MODULE_SIG_HASH)
>> -days 36500 \
>> -        -batch -x509 -config $(obj)/x509.genkey \
>> -        -outform PEM -out $(obj)/signing_key.pem \
>> -        -keyout $(obj)/signing_key.pem \
>> +    $(Q)openssl req -new -nodes -utf8 \
>> +        -batch -config $(obj)/x509.genkey \
>> +        -outform PEM -out $(obj)/signing_key.csr \
>> +        -keyout $(obj)/signing_key.key -extensions myexts \
>>           $($(quiet)redirect_openssl)
>> +    $(Q)openssl x509 -req -days 36500 -in $(obj)/signing_key.csr \
>> +        -outform PEM -out $(obj)/signing_key.crt \
>> +        -signkey $(obj)/signing_key.key \
>> +        -$(CONFIG_MODULE_SIG_HASH) -extensions myexts \
>> +        -extfile $(obj)/x509.genkey \
>> +        $($(quiet)redirect_openssl)
>> +    @cat $(obj)/signing_key.key $(obj)/signing_key.crt >>
>> $(obj)/signing_key.pem
>
>
> Could you not just rename signing_key.key to signing_key.pem (as it
> was before) and that would be it? Why do you need the .crt in that pem
> bundle?

I had also thought so, but the PEM file contains both the private key
and the certificate. I found the reasoning in the commit "fb1179499134
modsign: Use single PEM file for autogenerated key". I addressed your
other feedback in v2, posted just now.

Thanks & Regards,

      - Nayna