nfc: nci: constify several pointers to u8, sk_buff and other structs

Several functions receive pointers to u8, sk_buff or other structs but
do not modify the contents so make them const.  This allows doing the
same for local variables and in total makes the code a little bit safer.

This makes const also data passed as "unsigned long opt" argument to
nci_request() function.  Usual flow for such functions is:
1. Receive "u8 *" and store it (the pointer) in a structure
   allocated on stack (e.g. struct nci_set_config_param),
2. Call nci_request() or __nci_request() passing a callback function an
   the pointer to the structure via an "unsigned long opt",
3. nci_request() calls the callback which dereferences "unsigned long
   opt" in a read-only way.

This converts all above paths to use proper pointer to const data, so
entire flow is safer.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

1 files changed, 45 insertions, 38 deletions

diff --git a/net/nfc/nci/ntf.c b/net/nfc/nci/ntf.c
index 98af04c86b2c..d6251363b72b 100644
--- a/net/nfc/nci/ntf.c
+++ b/net/nfc/nci/ntf.c
@@ -28,10 +28,10 @@
 /* Handle NCI Notification packets */
 
 static void nci_core_reset_ntf_packet(struct nci_dev *ndev,
-				      struct sk_buff *skb)
+				      const struct sk_buff *skb)
 {
 	/* Handle NCI 2.x core reset notification */
-	struct nci_core_reset_ntf *ntf = (void *)skb->data;
+	const struct nci_core_reset_ntf *ntf = (void *)skb->data;
 
 	ndev->nci_ver = ntf->nci_ver;
 	pr_debug("nci_ver 0x%x, config_status 0x%x\n",
@@ -80,7 +80,7 @@ static void nci_core_conn_credits_ntf_packet(struct nci_dev *ndev,
 }
 
 static void nci_core_generic_error_ntf_packet(struct nci_dev *ndev,
-					      struct sk_buff *skb)
+					      const struct sk_buff *skb)
 {
 	__u8 status = skb->data[0];
 
@@ -107,9 +107,10 @@ static void nci_core_conn_intf_error_ntf_packet(struct nci_dev *ndev,
 		nci_data_exchange_complete(ndev, NULL, ntf->conn_id, -EIO);
 }
 
-static __u8 *nci_extract_rf_params_nfca_passive_poll(struct nci_dev *ndev,
-			struct rf_tech_specific_params_nfca_poll *nfca_poll,
-						     __u8 *data)
+static const __u8 *
+nci_extract_rf_params_nfca_passive_poll(struct nci_dev *ndev,
+					struct rf_tech_specific_params_nfca_poll *nfca_poll,
+					const __u8 *data)
 {
 	nfca_poll->sens_res = __le16_to_cpu(*((__le16 *)data));
 	data += 2;
@@ -134,9 +135,10 @@ static __u8 *nci_extract_rf_params_nfca_passive_poll(struct nci_dev *ndev,
 	return data;
 }
 
-static __u8 *nci_extract_rf_params_nfcb_passive_poll(struct nci_dev *ndev,
-			struct rf_tech_specific_params_nfcb_poll *nfcb_poll,
-						     __u8 *data)
+static const __u8 *
+nci_extract_rf_params_nfcb_passive_poll(struct nci_dev *ndev,
+					struct rf_tech_specific_params_nfcb_poll *nfcb_poll,
+					const __u8 *data)
 {
 	nfcb_poll->sensb_res_len = min_t(__u8, *data++, NFC_SENSB_RES_MAXSIZE);
 
@@ -148,9 +150,10 @@ static __u8 *nci_extract_rf_params_nfcb_passive_poll(struct nci_dev *ndev,
 	return data;
 }
 
-static __u8 *nci_extract_rf_params_nfcf_passive_poll(struct nci_dev *ndev,
-			struct rf_tech_specific_params_nfcf_poll *nfcf_poll,
-						     __u8 *data)
+static const __u8 *
+nci_extract_rf_params_nfcf_passive_poll(struct nci_dev *ndev,
+					struct rf_tech_specific_params_nfcf_poll *nfcf_poll,
+					const __u8 *data)
 {
 	nfcf_poll->bit_rate = *data++;
 	nfcf_poll->sensf_res_len = min_t(__u8, *data++, NFC_SENSF_RES_MAXSIZE);
@@ -164,9 +167,10 @@ static __u8 *nci_extract_rf_params_nfcf_passive_poll(struct nci_dev *ndev,
 	return data;
 }
 
-static __u8 *nci_extract_rf_params_nfcv_passive_poll(struct nci_dev *ndev,
-			struct rf_tech_specific_params_nfcv_poll *nfcv_poll,
-						     __u8 *data)
+static const __u8 *
+nci_extract_rf_params_nfcv_passive_poll(struct nci_dev *ndev,
+					struct rf_tech_specific_params_nfcv_poll *nfcv_poll,
+					const __u8 *data)
 {
 	++data;
 	nfcv_poll->dsfid = *data++;
@@ -175,9 +179,10 @@ static __u8 *nci_extract_rf_params_nfcv_passive_poll(struct nci_dev *ndev,
 	return data;
 }
 
-static __u8 *nci_extract_rf_params_nfcf_passive_listen(struct nci_dev *ndev,
-			struct rf_tech_specific_params_nfcf_listen *nfcf_listen,
-						     __u8 *data)
+static const __u8 *
+nci_extract_rf_params_nfcf_passive_listen(struct nci_dev *ndev,
+					  struct rf_tech_specific_params_nfcf_listen *nfcf_listen,
+					  const __u8 *data)
 {
 	nfcf_listen->local_nfcid2_len = min_t(__u8, *data++,
 					      NFC_NFCID2_MAXSIZE);
@@ -198,12 +203,12 @@ static int nci_add_new_protocol(struct nci_dev *ndev,
 				struct nfc_target *target,
 				__u8 rf_protocol,
 				__u8 rf_tech_and_mode,
-				void *params)
+				const void *params)
 {
-	struct rf_tech_specific_params_nfca_poll *nfca_poll;
-	struct rf_tech_specific_params_nfcb_poll *nfcb_poll;
-	struct rf_tech_specific_params_nfcf_poll *nfcf_poll;
-	struct rf_tech_specific_params_nfcv_poll *nfcv_poll;
+	const struct rf_tech_specific_params_nfca_poll *nfca_poll;
+	const struct rf_tech_specific_params_nfcb_poll *nfcb_poll;
+	const struct rf_tech_specific_params_nfcf_poll *nfcf_poll;
+	const struct rf_tech_specific_params_nfcv_poll *nfcv_poll;
 	__u32 protocol;
 
 	if (rf_protocol == NCI_RF_PROTOCOL_T1T)
@@ -274,7 +279,7 @@ static int nci_add_new_protocol(struct nci_dev *ndev,
 }
 
 static void nci_add_new_target(struct nci_dev *ndev,
-			       struct nci_rf_discover_ntf *ntf)
+			       const struct nci_rf_discover_ntf *ntf)
 {
 	struct nfc_target *target;
 	int i, rc;
@@ -319,10 +324,10 @@ void nci_clear_target_list(struct nci_dev *ndev)
 }
 
 static void nci_rf_discover_ntf_packet(struct nci_dev *ndev,
-				       struct sk_buff *skb)
+				       const struct sk_buff *skb)
 {
 	struct nci_rf_discover_ntf ntf;
-	__u8 *data = skb->data;
+	const __u8 *data = skb->data;
 	bool add_target = true;
 
 	ntf.rf_discovery_id = *data++;
@@ -382,7 +387,8 @@ static void nci_rf_discover_ntf_packet(struct nci_dev *ndev,
 }
 
 static int nci_extract_activation_params_iso_dep(struct nci_dev *ndev,
-			struct nci_rf_intf_activated_ntf *ntf, __u8 *data)
+						 struct nci_rf_intf_activated_ntf *ntf,
+						 const __u8 *data)
 {
 	struct activation_params_nfca_poll_iso_dep *nfca_poll;
 	struct activation_params_nfcb_poll_iso_dep *nfcb_poll;
@@ -418,7 +424,8 @@ static int nci_extract_activation_params_iso_dep(struct nci_dev *ndev,
 }
 
 static int nci_extract_activation_params_nfc_dep(struct nci_dev *ndev,
-			struct nci_rf_intf_activated_ntf *ntf, __u8 *data)
+						 struct nci_rf_intf_activated_ntf *ntf,
+						 const __u8 *data)
 {
 	struct activation_params_poll_nfc_dep *poll;
 	struct activation_params_listen_nfc_dep *listen;
@@ -454,7 +461,7 @@ static int nci_extract_activation_params_nfc_dep(struct nci_dev *ndev,
 }
 
 static void nci_target_auto_activated(struct nci_dev *ndev,
-				      struct nci_rf_intf_activated_ntf *ntf)
+				      const struct nci_rf_intf_activated_ntf *ntf)
 {
 	struct nfc_target *target;
 	int rc;
@@ -477,7 +484,7 @@ static void nci_target_auto_activated(struct nci_dev *ndev,
 }
 
 static int nci_store_general_bytes_nfc_dep(struct nci_dev *ndev,
-		struct nci_rf_intf_activated_ntf *ntf)
+					   const struct nci_rf_intf_activated_ntf *ntf)
 {
 	ndev->remote_gb_len = 0;
 
@@ -519,11 +526,11 @@ static int nci_store_general_bytes_nfc_dep(struct nci_dev *ndev,
 }
 
 static void nci_rf_intf_activated_ntf_packet(struct nci_dev *ndev,
-					     struct sk_buff *skb)
+					     const struct sk_buff *skb)
 {
 	struct nci_conn_info    *conn_info;
 	struct nci_rf_intf_activated_ntf ntf;
-	__u8 *data = skb->data;
+	const __u8 *data = skb->data;
 	int err = NCI_STATUS_OK;
 
 	ntf.rf_discovery_id = *data++;
@@ -681,10 +688,10 @@ listen:
 }
 
 static void nci_rf_deactivate_ntf_packet(struct nci_dev *ndev,
-					 struct sk_buff *skb)
+					 const struct sk_buff *skb)
 {
-	struct nci_conn_info    *conn_info;
-	struct nci_rf_deactivate_ntf *ntf = (void *) skb->data;
+	const struct nci_conn_info *conn_info;
+	const struct nci_rf_deactivate_ntf *ntf = (void *)skb->data;
 
 	pr_debug("entry, type 0x%x, reason 0x%x\n", ntf->type, ntf->reason);
 
@@ -725,10 +732,10 @@ static void nci_rf_deactivate_ntf_packet(struct nci_dev *ndev,
 }
 
 static void nci_nfcee_discover_ntf_packet(struct nci_dev *ndev,
-					  struct sk_buff *skb)
+					  const struct sk_buff *skb)
 {
 	u8 status = NCI_STATUS_OK;
-	struct nci_nfcee_discover_ntf   *nfcee_ntf =
+	const struct nci_nfcee_discover_ntf *nfcee_ntf =
 				(struct nci_nfcee_discover_ntf *)skb->data;
 
 	pr_debug("\n");
@@ -745,7 +752,7 @@ static void nci_nfcee_discover_ntf_packet(struct nci_dev *ndev,
 }
 
 static void nci_nfcee_action_ntf_packet(struct nci_dev *ndev,
-					struct sk_buff *skb)
+					const struct sk_buff *skb)
 {
 	pr_debug("\n");
 }