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, 8 insertions, 6 deletions

diff --git a/include/net/nfc/nci_core.h b/include/net/nfc/nci_core.h
index 00f2c60971d7..4770a81f4aa7 100644
--- a/include/net/nfc/nci_core.h
+++ b/include/net/nfc/nci_core.h
@@ -278,23 +278,25 @@ int nci_request(struct nci_dev *ndev,
 		void (*req)(struct nci_dev *ndev,
 			    unsigned long opt),
 		unsigned long opt, __u32 timeout);
-int nci_prop_cmd(struct nci_dev *ndev, __u8 oid, size_t len, __u8 *payload);
-int nci_core_cmd(struct nci_dev *ndev, __u16 opcode, size_t len, __u8 *payload);
+int nci_prop_cmd(struct nci_dev *ndev, __u8 oid, size_t len,
+		 const __u8 *payload);
+int nci_core_cmd(struct nci_dev *ndev, __u16 opcode, size_t len,
+		 const __u8 *payload);
 int nci_core_reset(struct nci_dev *ndev);
 int nci_core_init(struct nci_dev *ndev);
 
 int nci_recv_frame(struct nci_dev *ndev, struct sk_buff *skb);
 int nci_send_frame(struct nci_dev *ndev, struct sk_buff *skb);
-int nci_set_config(struct nci_dev *ndev, __u8 id, size_t len, __u8 *val);
+int nci_set_config(struct nci_dev *ndev, __u8 id, size_t len, const __u8 *val);
 
 int nci_nfcee_discover(struct nci_dev *ndev, u8 action);
 int nci_nfcee_mode_set(struct nci_dev *ndev, u8 nfcee_id, u8 nfcee_mode);
 int nci_core_conn_create(struct nci_dev *ndev, u8 destination_type,
 			 u8 number_destination_params,
 			 size_t params_len,
-			 struct core_conn_create_dest_spec_params *params);
+			 const struct core_conn_create_dest_spec_params *params);
 int nci_core_conn_close(struct nci_dev *ndev, u8 conn_id);
-int nci_nfcc_loopback(struct nci_dev *ndev, void *data, size_t data_len,
+int nci_nfcc_loopback(struct nci_dev *ndev, const void *data, size_t data_len,
 		      struct sk_buff **resp);
 
 struct nci_hci_dev *nci_hci_allocate(struct nci_dev *ndev);
@@ -378,7 +380,7 @@ void nci_req_complete(struct nci_dev *ndev, int result);
 struct nci_conn_info *nci_get_conn_info_by_conn_id(struct nci_dev *ndev,
 						   int conn_id);
 int nci_get_conn_info_by_dest_type_params(struct nci_dev *ndev, u8 dest_type,
-					  struct dest_spec_params *params);
+					  const struct dest_spec_params *params);
 
 /* ----- NCI status code ----- */
 int nci_to_errno(__u8 code);