diff mbox series

[RFC,1/8] certs: Introduce ability to link to a system key

Message ID 20240311161111.3268190-2-eric.snowberg@oracle.com
State New
Headers show
Series Clavis LSM | expand

Commit Message

Eric Snowberg March 11, 2024, 4:11 p.m. UTC 
Introduce a new function to allow a keyring to link to a key contained
within one of the system keyrings (builtin, secondary, or platform).
Depending on how the kernel is built, if the machine keyring is
available, it will be checked as well, since it is linked to the secondary
keyring. If the asymmetric key id matches a key within one of these
system keyrings, the matching key is linked into the passed in
keyring.

Signed-off-by: Eric Snowberg <eric.snowberg@oracle.com>
---
 certs/system_keyring.c        | 29 +++++++++++++++++++++++++++++
 include/keys/system_keyring.h |  7 ++++++-
 2 files changed, 35 insertions(+), 1 deletion(-)

Comments

Jarkko Sakkinen March 11, 2024, 7:18 p.m. UTC | #1 
On Mon Mar 11, 2024 at 6:11 PM EET, Eric Snowberg wrote:
> +	return -1;

Missed this one: why a magic number?

BR, Jarkko
Eric Snowberg March 11, 2024, 9:31 p.m. UTC | #2 
> On Mar 11, 2024, at 1:18 PM, Jarkko Sakkinen <jarkko@kernel.org> wrote:
> 
> On Mon Mar 11, 2024 at 6:11 PM EET, Eric Snowberg wrote:
>> + return -1;
> 
> Missed this one: why a magic number?

Good point, I'll change this to return -ENOKEY.  Thanks.
Bharat Bhushan March 12, 2024, 6 a.m. UTC | #3 
> -----Original Message-----
> From: Eric Snowberg <eric.snowberg@oracle.com>
> Sent: Monday, March 11, 2024 9:41 PM
> To: linux-security-module@vger.kernel.org
> Cc: dhowells@redhat.com; dwmw2@infradead.org;
> herbert@gondor.apana.org.au; davem@davemloft.net; ardb@kernel.org;
> jarkko@kernel.org; paul@paul-moore.com; jmorris@namei.org;
> serge@hallyn.com; zohar@linux.ibm.com; roberto.sassu@huawei.com;
> dmitry.kasatkin@gmail.com; mic@digikod.net; casey@schaufler-ca.com;
> stefanb@linux.ibm.com; eric.snowberg@oracle.com; linux-
> kernel@vger.kernel.org; keyrings@vger.kernel.org; linux-
> crypto@vger.kernel.org; linux-efi@vger.kernel.org; linux-
> integrity@vger.kernel.org
> Subject: [EXTERNAL] [PATCH RFC 1/8] certs: Introduce ability to link to a
> system key
> 
> Prioritize security for external emails: Confirm sender and content safety
> before clicking links or opening attachments
> 
> ----------------------------------------------------------------------
> Introduce a new function to allow a keyring to link to a key contained
> within one of the system keyrings (builtin, secondary, or platform).
> Depending on how the kernel is built, if the machine keyring is
> available, it will be checked as well, since it is linked to the secondary
> keyring. If the asymmetric key id matches a key within one of these
> system keyrings, the matching key is linked into the passed in
> keyring.
> 
> Signed-off-by: Eric Snowberg <eric.snowberg@oracle.com>
> ---
>  certs/system_keyring.c        | 29 +++++++++++++++++++++++++++++
>  include/keys/system_keyring.h |  7 ++++++-
>  2 files changed, 35 insertions(+), 1 deletion(-)
> 
> diff --git a/certs/system_keyring.c b/certs/system_keyring.c
> index 9de610bf1f4b..b647be49f6e0 100644
> --- a/certs/system_keyring.c
> +++ b/certs/system_keyring.c
> @@ -426,3 +426,32 @@ void __init set_platform_trusted_keys(struct key
> *keyring)
>  	platform_trusted_keys = keyring;
>  }
>  #endif
> +
> +/**
> + * system_key_link - Link to a system key
> + * @keyring: The keyring to link into
> + * @id: The asymmetric key id to look for in the system keyring
> + */
> +int system_key_link(struct key *keyring, struct asymmetric_key_id *id)
> +{
> +	struct key *tkey;
> +
> +#ifdef CONFIG_SECONDARY_TRUSTED_KEYRING
> +	tkey = find_asymmetric_key(secondary_trusted_keys, id, NULL, NULL,
> false);
> +#else
> +	tkey = find_asymmetric_key(builtin_trusted_keys, id, NULL, NULL,
> false);
> +#endif
> +	if (!IS_ERR(tkey))
> +		goto found;
> +
> +	tkey = find_asymmetric_key(platform_trusted_keys, id, NULL, NULL,
> false);
> +
> +	if (!IS_ERR(tkey))
> +		goto found;
> +
> +	return -1;

Please use -ENOKEY.

Thanks
-Bharat

> +
> +found:
> +	key_link(keyring, tkey);
> +	return 0;
> +}
> diff --git a/include/keys/system_keyring.h b/include/keys/system_keyring.h
> index 8365adf842ef..b47ac8e2001a 100644
> --- a/include/keys/system_keyring.h
> +++ b/include/keys/system_keyring.h
> @@ -9,6 +9,7 @@
>  #define _KEYS_SYSTEM_KEYRING_H
> 
>  #include <linux/key.h>
> +struct asymmetric_key_id;
> 
>  enum blacklist_hash_type {
>  	/* TBSCertificate hash */
> @@ -28,7 +29,7 @@ int restrict_link_by_digsig_builtin(struct key
> *dest_keyring,
>  				    const union key_payload *payload,
>  				    struct key *restriction_key);
>  extern __init int load_module_cert(struct key *keyring);
> -
> +extern int system_key_link(struct key *keyring, struct asymmetric_key_id
> *id);
>  #else
>  #define restrict_link_by_builtin_trusted restrict_link_reject
>  #define restrict_link_by_digsig_builtin restrict_link_reject
> @@ -38,6 +39,10 @@ static inline __init int load_module_cert(struct key
> *keyring)
>  	return 0;
>  }
> 
> +static inline int system_key_link(struct key *keyring, struct asymmetric_key_id
> *id)
> +{
> +	return 0;
> +}
>  #endif
> 
>  #ifdef CONFIG_SECONDARY_TRUSTED_KEYRING
> --
> 2.39.3
>
Jarkko Sakkinen March 12, 2024, 3:18 p.m. UTC | #4 
On Mon Mar 11, 2024 at 11:31 PM EET, Eric Snowberg wrote:
>
>
> > On Mar 11, 2024, at 1:18 PM, Jarkko Sakkinen <jarkko@kernel.org> wrote:
> > 
> > On Mon Mar 11, 2024 at 6:11 PM EET, Eric Snowberg wrote:
> >> + return -1;
> > 
> > Missed this one: why a magic number?
>
> Good point, I'll change this to return -ENOKEY.  Thanks.

Either that or a boolean function, which ever fits to the overall
flow better... The upside of error code is less branching in the call
sites. The upside of boolean is that caller exactly knows all the
values that ever should come out as a result.

Your choice ofc.

BR, Jarkko
Mimi Zohar April 4, 2024, 10:40 p.m. UTC | #5 
Hi Eric,

> diff --git a/certs/system_keyring.c b/certs/system_keyring.c
> index 9de610bf1f4b..b647be49f6e0 100644
> --- a/certs/system_keyring.c
> +++ b/certs/system_keyring.c
> @@ -426,3 +426,32 @@ void __init set_platform_trusted_keys(struct key
> *keyring)
>  	platform_trusted_keys = keyring;
>  }
>  #endif
> +
> +/**
> + * system_key_link - Link to a system key
> + * @keyring: The keyring to link into
> + * @id: The asymmetric key id to look for in the system keyring
> + */
> +int system_key_link(struct key *keyring, struct asymmetric_key_id *id)
> +{
> +	struct key *tkey;
> +
> +#ifdef CONFIG_SECONDARY_TRUSTED_KEYRING
> +	tkey = find_asymmetric_key(secondary_trusted_keys, id, NULL, NULL,
> false);
> +#else
> +	tkey = find_asymmetric_key(builtin_trusted_keys, id, NULL, NULL, false);
> +#endif
> +	if (!IS_ERR(tkey))
> +		goto found;
> +
> +	tkey = find_asymmetric_key(platform_trusted_keys, id, NULL, NULL,
> false);
> +
> +	if (!IS_ERR(tkey))
> +		goto found;
> +
> +	return -1;

Normally "goto" is for the error.  Invert the logic. 

Mimi

> +
> +found:
> +	key_link(keyring, tkey);
> +	return 0;
> +}
>
Eric Snowberg April 5, 2024, 12:56 p.m. UTC | #6 
> On Apr 4, 2024, at 4:40 PM, Mimi Zohar <zohar@linux.ibm.com> wrote:
> 
> Hi Eric,
> 
>> diff --git a/certs/system_keyring.c b/certs/system_keyring.c
>> index 9de610bf1f4b..b647be49f6e0 100644
>> --- a/certs/system_keyring.c
>> +++ b/certs/system_keyring.c
>> @@ -426,3 +426,32 @@ void __init set_platform_trusted_keys(struct key
>> *keyring)
>> platform_trusted_keys = keyring;
>> }
>> #endif
>> +
>> +/**
>> + * system_key_link - Link to a system key
>> + * @keyring: The keyring to link into
>> + * @id: The asymmetric key id to look for in the system keyring
>> + */
>> +int system_key_link(struct key *keyring, struct asymmetric_key_id *id)
>> +{
>> + struct key *tkey;
>> +
>> +#ifdef CONFIG_SECONDARY_TRUSTED_KEYRING
>> + tkey = find_asymmetric_key(secondary_trusted_keys, id, NULL, NULL,
>> false);
>> +#else
>> + tkey = find_asymmetric_key(builtin_trusted_keys, id, NULL, NULL, false);
>> +#endif
>> + if (!IS_ERR(tkey))
>> + goto found;
>> +
>> + tkey = find_asymmetric_key(platform_trusted_keys, id, NULL, NULL,
>> false);
>> +
>> + if (!IS_ERR(tkey))
>> + goto found;
>> +
>> + return -1;
> 
> Normally "goto" is for the error.  Invert the logic. 

Ok, I'll change that in the next version.  Thanks.
diff mbox series

Patch

diff --git a/certs/system_keyring.c b/certs/system_keyring.c
index 9de610bf1f4b..b647be49f6e0 100644
--- a/certs/system_keyring.c
+++ b/certs/system_keyring.c
@@ -426,3 +426,32 @@  void __init set_platform_trusted_keys(struct key *keyring)
 	platform_trusted_keys = keyring;
 }
 #endif
+
+/**
+ * system_key_link - Link to a system key
+ * @keyring: The keyring to link into
+ * @id: The asymmetric key id to look for in the system keyring
+ */
+int system_key_link(struct key *keyring, struct asymmetric_key_id *id)
+{
+	struct key *tkey;
+
+#ifdef CONFIG_SECONDARY_TRUSTED_KEYRING
+	tkey = find_asymmetric_key(secondary_trusted_keys, id, NULL, NULL, false);
+#else
+	tkey = find_asymmetric_key(builtin_trusted_keys, id, NULL, NULL, false);
+#endif
+	if (!IS_ERR(tkey))
+		goto found;
+
+	tkey = find_asymmetric_key(platform_trusted_keys, id, NULL, NULL, false);
+
+	if (!IS_ERR(tkey))
+		goto found;
+
+	return -1;
+
+found:
+	key_link(keyring, tkey);
+	return 0;
+}
diff --git a/include/keys/system_keyring.h b/include/keys/system_keyring.h
index 8365adf842ef..b47ac8e2001a 100644
--- a/include/keys/system_keyring.h
+++ b/include/keys/system_keyring.h
@@ -9,6 +9,7 @@ 
 #define _KEYS_SYSTEM_KEYRING_H
 
 #include <linux/key.h>
+struct asymmetric_key_id;
 
 enum blacklist_hash_type {
 	/* TBSCertificate hash */
@@ -28,7 +29,7 @@  int restrict_link_by_digsig_builtin(struct key *dest_keyring,
 				    const union key_payload *payload,
 				    struct key *restriction_key);
 extern __init int load_module_cert(struct key *keyring);
-
+extern int system_key_link(struct key *keyring, struct asymmetric_key_id *id);
 #else
 #define restrict_link_by_builtin_trusted restrict_link_reject
 #define restrict_link_by_digsig_builtin restrict_link_reject
@@ -38,6 +39,10 @@  static inline __init int load_module_cert(struct key *keyring)
 	return 0;
 }
 
+static inline int system_key_link(struct key *keyring, struct asymmetric_key_id *id)
+{
+	return 0;
+}
 #endif
 
 #ifdef CONFIG_SECONDARY_TRUSTED_KEYRING