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authorStefan Kerkmann <karlk90@pm.me>2022-08-06 10:46:59 +0200
committerGitHub <noreply@github.com>2022-08-06 18:46:59 +1000
commited9bdcbc3608819e17ff7a11221e651bf51ec1cc (patch)
tree36e87885a316d67edc7fe64a04ca0db90c890e4c
parentcac704241404908794514b7a534e58c96aff4d6b (diff)
downloadqmk_firmware-ed9bdcbc3608819e17ff7a11221e651bf51ec1cc.tar.gz
qmk_firmware-ed9bdcbc3608819e17ff7a11221e651bf51ec1cc.zip
[Core] guard RPC invocation by checking RPC info against crc checksum (#17840)
-rw-r--r--quantum/split_common/transactions.c18
-rw-r--r--quantum/split_common/transport.h9
2 files changed, 18 insertions, 9 deletions
diff --git a/quantum/split_common/transactions.c b/quantum/split_common/transactions.c
index 9e3df534e3..719068908f 100644
--- a/quantum/split_common/transactions.c
+++ b/quantum/split_common/transactions.c
@@ -694,7 +694,7 @@ split_transaction_desc_t split_transaction_table[NUM_TOTAL_TRANSACTIONS] = {
#if defined(SPLIT_TRANSACTION_IDS_KB) || defined(SPLIT_TRANSACTION_IDS_USER)
[PUT_RPC_INFO] = trans_initiator2target_initializer_cb(rpc_info, slave_rpc_info_callback),
[PUT_RPC_REQ_DATA] = trans_initiator2target_initializer(rpc_m2s_buffer),
- [EXECUTE_RPC] = trans_initiator2target_initializer_cb(rpc_info.transaction_id, slave_rpc_exec_callback),
+ [EXECUTE_RPC] = trans_initiator2target_initializer_cb(rpc_info.payload.transaction_id, slave_rpc_exec_callback),
[GET_RPC_RESP_DATA] = trans_target2initiator_initializer(rpc_s2m_buffer),
#endif // defined(SPLIT_TRANSACTION_IDS_KB) || defined(SPLIT_TRANSACTION_IDS_USER)
};
@@ -760,7 +760,8 @@ bool transaction_rpc_exec(int8_t transaction_id, uint8_t initiator2target_buffer
if (target2initiator_buffer_size > RPC_S2M_BUFFER_SIZE) return false;
// Prepare the metadata block
- rpc_sync_info_t info = {.transaction_id = transaction_id, .m2s_length = initiator2target_buffer_size, .s2m_length = target2initiator_buffer_size};
+ rpc_sync_info_t info = {.payload = {.transaction_id = transaction_id, .m2s_length = initiator2target_buffer_size, .s2m_length = target2initiator_buffer_size}};
+ info.checksum = crc8(&info.payload, sizeof(info.payload));
// Make sure the local side knows that we're not sending the full block of data
split_transaction_table[PUT_RPC_REQ_DATA].initiator2target_buffer_size = initiator2target_buffer_size;
@@ -791,18 +792,23 @@ void slave_rpc_info_callback(uint8_t initiator2target_buffer_size, const void *i
// Ignore the args -- the `split_shmem` already has the info, we just need to act upon it.
// We must keep the `split_transaction_table` non-const, so that it is able to be modified at runtime.
- split_transaction_table[PUT_RPC_REQ_DATA].initiator2target_buffer_size = split_shmem->rpc_info.m2s_length;
- split_transaction_table[GET_RPC_RESP_DATA].target2initiator_buffer_size = split_shmem->rpc_info.s2m_length;
+ split_transaction_table[PUT_RPC_REQ_DATA].initiator2target_buffer_size = split_shmem->rpc_info.payload.m2s_length;
+ split_transaction_table[GET_RPC_RESP_DATA].target2initiator_buffer_size = split_shmem->rpc_info.payload.s2m_length;
}
void slave_rpc_exec_callback(uint8_t initiator2target_buffer_size, const void *initiator2target_buffer, uint8_t target2initiator_buffer_size, void *target2initiator_buffer) {
// We can assume that the buffer lengths are correctly set, now, given that sequentially the rpc_info callback was already executed.
// Go through the rpc_info and execute _that_ transaction's callback, with the scratch buffers as inputs.
- int8_t transaction_id = split_shmem->rpc_info.transaction_id;
+ // As a safety precaution we check that the received payload matches its checksum first.
+ if (crc8(&split_shmem->rpc_info.payload, sizeof(split_shmem->rpc_info.payload)) != split_shmem->rpc_info.checksum) {
+ return;
+ }
+
+ int8_t transaction_id = split_shmem->rpc_info.payload.transaction_id;
if (transaction_id < NUM_TOTAL_TRANSACTIONS) {
split_transaction_desc_t *trans = &split_transaction_table[transaction_id];
if (trans->slave_callback) {
- trans->slave_callback(split_shmem->rpc_info.m2s_length, split_shmem->rpc_m2s_buffer, split_shmem->rpc_info.s2m_length, split_shmem->rpc_s2m_buffer);
+ trans->slave_callback(split_shmem->rpc_info.payload.m2s_length, split_shmem->rpc_m2s_buffer, split_shmem->rpc_info.payload.s2m_length, split_shmem->rpc_s2m_buffer);
}
}
}
diff --git a/quantum/split_common/transport.h b/quantum/split_common/transport.h
index e62679990a..06778ad14a 100644
--- a/quantum/split_common/transport.h
+++ b/quantum/split_common/transport.h
@@ -116,9 +116,12 @@ typedef struct _split_slave_pointing_sync_t {
#if defined(SPLIT_TRANSACTION_IDS_KB) || defined(SPLIT_TRANSACTION_IDS_USER)
typedef struct _rpc_sync_info_t {
- int8_t transaction_id;
- uint8_t m2s_length;
- uint8_t s2m_length;
+ uint8_t checksum;
+ struct {
+ int8_t transaction_id;
+ uint8_t m2s_length;
+ uint8_t s2m_length;
+ } payload;
} rpc_sync_info_t;
#endif // defined(SPLIT_TRANSACTION_IDS_KB) || defined(SPLIT_TRANSACTION_IDS_USER)