[PATCH v3 4/5] crypto: ccp: Fix sample application signature passing

Mario Limonciello
2023-08-29T17:34:46Z

When parameters are sent the PSP returns back it's own signature
for the application to verify the authenticity of the result.

Display this signature to the caller instead of the one the caller
sent.

Fixes: f40d42f116cf ("crypto: ccp - Add a sample python script for Dynamic Boost Control")
Fixes: febe3ed3222f ("crypto: ccp - Add a sample library for ioctl use")
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
---
tools/crypto/ccp/dbc.c | 1 +
tools/crypto/ccp/dbc.py | 5 +++--
2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/tools/crypto/ccp/dbc.c b/tools/crypto/ccp/dbc.c
index 7774e981849f..a807df0f0597 100644
--- a/tools/crypto/ccp/dbc.c
+++ b/tools/crypto/ccp/dbc.c
@@ -68,5 +68,6 @@ int process_param(int fd, int msg_index, __u8 *signature, int *data)
return errno;

*data = tmp.param;
+ memcpy(signature, tmp.signature, sizeof(tmp.signature));
return 0;
}
diff --git a/tools/crypto/ccp/dbc.py b/tools/crypto/ccp/dbc.py
index 3956efe7537a..2b91415b1940 100644
--- a/tools/crypto/ccp/dbc.py
+++ b/tools/crypto/ccp/dbc.py
@@ -57,7 +57,8 @@ def process_param(device, message, signature, data=None):
if type(message) != tuple:
raise ValueError("Expected message tuple")
arg = ctypes.c_int(data if data else 0)
- ret = lib.process_param(device.fileno(), message[0], signature, ctypes.pointer(arg))
+ sig = ctypes.create_string_buffer(signature, len(signature))
+ ret = lib.process_param(device.fileno(), message[0], ctypes.pointer(sig), ctypes.pointer(arg))
if ret:
handle_error(ret)
- return arg, signature
+ return arg.value, sig.value
--
2.34.1