Hi Tudor,
On 02/28/2018 10:52 AM, Tudor Ambarus wrote:
Provide three new operations in the key_type struct that can be used to
provide access to kpp operations. These will be implemented for the
asymmetric key type in a later patch and may refer to a key retained in
RAM by the kernel or a key retained in crypto hardware.
int (*asym_kpp_query)(const struct kernel_kpp_params *params,
struct kernel_kpp_query *res);
int (*asym_kpp_gen_pubkey)(struct kernel_kpp_params *params,
void *out);
int (*asym_kpp_compute_ss)(struct kernel_kpp_params *params,
const void *in, void *out);
Signed-off-by: Tudor Ambarus <tudor.ambarus@xxxxxxxxxxxxx>
---
Documentation/security/keys/core.rst | 54 ++++++++++++++++++++++++++++++++++++
include/linux/key-type.h | 7 +++++
include/linux/keyctl.h | 11 ++++++++
include/uapi/linux/keyctl.h | 3 ++
4 files changed, 75 insertions(+)
diff --git a/Documentation/security/keys/core.rst b/Documentation/security/keys/core.rst
index d224fd0..9b69a1f 100644
--- a/Documentation/security/keys/core.rst
+++ b/Documentation/security/keys/core.rst
@@ -1688,6 +1688,60 @@ The structure has a number of fields, some of which are mandatory:
If successful, 0 will be returned. If the key doesn't support this,
EOPNOTSUPP will be returned.
+ * ``int (*asym_kpp_gen_pubkey)(struct kernel_kpp_params *params, void *out);``
+ * ``int (*asym_kpp_compute_ss)(struct kernel_kpp_params *params, const void *in, void *out);``
+
+ These methods are optional. If provided the first allows to generate the
+ public key pair corresponding to the private key. The second method allows
+ to generate a shared secret by combining the private key and the other
+ party's public key.
+
+ In all cases, the following information is provided in the params block::
+
+ struct kernel_kpp_query {
+ struct key *key;
+ __u32 in_len; /* Input data size */
+ __u32 out_len; /* Output buffer size */
+ }
+
Probably not a huge deal as most common key sizes are already supported,
but... is there a way to query supported key sizes? I think for
DH_COMPUTE we didn't have this problem as everything was done in
software. However, if the intent is to use TPM / other hardware engines
we might need a way to query supported key sizes.
+ This includes the key to be used and the sizes in bytes of the input and
+ output buffers.
+
+ For a given operation, the in and out buffers are used as follows::
+
+ Operation ID in,in_len out,out_len
+ ======================= =================== ========================
+ KEYCTL_KPP_GEN_PUBKEY - Corresponding public key
+ KEYCTL_KPP_COMPUTE_SS Pair's public key Shared Secret
+
+ If successful, the public key generation and the shared secret computation
+ will return the amount of data written into the output buffer.
+
+ * ``int (*asym_kpp_query)(const struct kernel_kpp_params *params, struct kernel_kpp_query *res);``
+
+ This method is optional. If provided it allows information about the
+ asymmetric KPP (Key Protocol Primitives) key held in the key to be
+ determined.
+
+ The ``params`` block will contain the key to be queried. ``in_len`` and
+ ``out_len`` are unused.
+
+ If successful, the following information is filled in::
+
+ struct kernel_kpp_query {
+ __u32 supported_ops; /* Which ops are supported */
+ __u32 max_size; /* Maximum size of the output buffer */
+ };
+
+ The supported_ops field will contain a bitmask indicating what operations
+ are supported by the key, including public key generation and shared
+ secret computation. The following constants are defined for this::
+
+ KEYCTL_SUPPORTS_{GEN_PUBKEY, COMPUTE_SS};
+
+ If successful, 0 is returned. If the key is not an asymmetric kpp key,
+ EOPNOTSUPP is returned.
+
Request-Key Callback Service
============================
diff --git a/include/linux/key-type.h b/include/linux/key-type.h
index bc9af55..d354b6b 100644
--- a/include/linux/key-type.h
+++ b/include/linux/key-type.h
@@ -19,6 +19,8 @@
struct kernel_pkey_query;
struct kernel_pkey_params;
+struct kernel_kpp_query;
+struct kernel_kpp_params;
/*
* key under-construction record
@@ -165,6 +167,11 @@ struct key_type {
const void *in, void *out);
int (*asym_verify_signature)(struct kernel_pkey_params *params,
const void *in, const void *in2);
+ int (*asym_kpp_query)(const struct kernel_kpp_params *params,
+ struct kernel_kpp_query *res);
+ int (*asym_kpp_gen_pubkey)(struct kernel_kpp_params *params, void *out);
+ int (*asym_kpp_compute_ss)(struct kernel_kpp_params *params,
+ const void *in, void *out);
/* internal fields */
struct list_head link; /* link in types list */
diff --git a/include/linux/keyctl.h b/include/linux/keyctl.h
index e89b4a4..8f464ea 100644
--- a/include/linux/keyctl.h
+++ b/include/linux/keyctl.h
@@ -43,4 +43,15 @@ struct kernel_pkey_params {
enum kernel_pkey_operation op : 8;
};
+struct kernel_kpp_query {
+ __u32 supported_ops; /* Which ops are supported */
+ __u32 max_size; /* Maximum size of the output buffer */
+};
+
+struct kernel_kpp_params {
+ struct key *key;
+ __u32 in_len; /* Input data size */
+ __u32 out_len; /* Output buffer size */
+};
+
#endif /* __LINUX_KEYCTL_H */
diff --git a/include/uapi/linux/keyctl.h b/include/uapi/linux/keyctl.h
index d75d208..98b79f8 100644
--- a/include/uapi/linux/keyctl.h
+++ b/include/uapi/linux/keyctl.h
@@ -107,4 +107,7 @@ struct keyctl_pkey_params {
__u32 __spare[7];
};
+#define KEYCTL_SUPPORTS_GEN_PUBKEY 0x0f
This looks fishy, the other KEYCTL_SUPPORTS_ block ends at 0x08. This
would imply that KPP supports encryption, decryption, sign, verify. Do
you mean 0x10 here?
+#define KEYCTL_SUPPORTS_COMPUTE_SS 0x10
+
And 0x20 here?
#endif /* _LINUX_KEYCTL_H */
Otherwise this looks good to me. Feel free to add:
Reviewed-by: Denis Kenzior <denkenz@xxxxxxxxx>
Regards,
-Denis
