net: nfc: Propagate ISO14443 type A target ATS to userspace via netlink

Add a 20-byte field ats to struct nfc_target and expose it as
NFC_ATTR_TARGET_ATS via the netlink interface. The payload contains
'historical bytes' that help to distinguish cards from one another.
The information is commonly used to assemble an emulated ATR similar
to that reported by smart cards with contacts.

Add a 20-byte field target_ats to struct nci_dev to hold the payload
obtained in nci_rf_intf_activated_ntf_packet() and copy it to over to
nfc_target.ats in nci_activate_target(). The approach is similar
to the handling of 'general bytes' within ATR_RES.

Replace the hard-coded size of rats_res within struct
activation_params_nfca_poll_iso_dep by the equal constant NFC_ATS_MAXSIZE
now defined in nfc.h

Within NCI, the information corresponds to the 'RATS Response' activation
parameter that omits the initial length byte TL. This loses no
information and is consistent with our handling of SENSB_RES that
also drops the first (constant) byte.

Tested with nxp_nci_i2c on a few type A targets including an
ICAO 9303 compliant passport.

I refrain from the corresponding change to digital_in_recv_ats()
to have the few drivers based on digital.h fill nfc_target.ats,
as I have no way to test it. That class of drivers appear not to set
NFC_ATTR_TARGET_SENSB_RES either. Consider a separate patch to propagate
(all) the parameters.

Signed-off-by: Juraj Šarinay <juraj@sarinay.com>
Link: https://patch.msgid.link/20241103124525.8392-1-juraj@sarinay.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

diff --git a/include/net/nfc/nci.h b/include/net/nfc/nci.h
index dc36519d16aada94fa1dafe7113861428b220ebd..09efcaed7c3f65b9b8cc13e96fadddabd21668ae 100644 (file)
--- a/include/net/nfc/nci.h
+++ b/include/net/nfc/nci.h
@@ -475,7 +475,7 @@ struct nci_rf_discover_ntf {
 #define NCI_OP_RF_INTF_ACTIVATED_NTF   nci_opcode_pack(NCI_GID_RF_MGMT, 0x05)
 struct activation_params_nfca_poll_iso_dep {
        __u8    rats_res_len;
-       __u8    rats_res[20];
+       __u8    rats_res[NFC_ATS_MAXSIZE];
 };
 
 struct activation_params_nfcb_poll_iso_dep {

diff --git a/include/net/nfc/nci_core.h b/include/net/nfc/nci_core.h
index ea8595651c3846d288a5404b13caf82e10222239..e180bdf2f82b0184bee44a2684dcb5e1cdcdc93f 100644 (file)
--- a/include/net/nfc/nci_core.h
+++ b/include/net/nfc/nci_core.h
@@ -265,6 +265,10 @@ struct nci_dev {
        /* stored during intf_activated_ntf */
        __u8 remote_gb[NFC_MAX_GT_LEN];
        __u8 remote_gb_len;
+
+       /* stored during intf_activated_ntf */
+       __u8 target_ats[NFC_ATS_MAXSIZE];
+       __u8 target_ats_len;
 };
 
 /* ----- NCI Devices ----- */

diff --git a/include/net/nfc/nfc.h b/include/net/nfc/nfc.h
index 3a3781838c67262b74de33988beb4c1f8d09c569..127e6c7d910dcb264878ac06ef0a6ada8135fc18 100644 (file)
--- a/include/net/nfc/nfc.h
+++ b/include/net/nfc/nfc.h
@@ -86,6 +86,8 @@ struct nfc_ops {
  *     is a type A one. The %sens_res most significant byte must be byte 2
  *     as described by the NFC Forum digital specification (i.e. the platform
  *     configuration one) while %sens_res least significant byte is byte 1.
+ * @ats_len: length of Answer To Select in bytes
+ * @ats: Answer To Select returned by an ISO 14443 Type A target upon activation
  */
 struct nfc_target {
        u32 idx;
@@ -105,6 +107,8 @@ struct nfc_target {
        u8 is_iso15693;
        u8 iso15693_dsfid;
        u8 iso15693_uid[NFC_ISO15693_UID_MAXSIZE];
+       u8 ats_len;
+       u8 ats[NFC_ATS_MAXSIZE];
 };
 
 /**

diff --git a/include/uapi/linux/nfc.h b/include/uapi/linux/nfc.h
index 4fa4e979e948a57a41f3897d8d05bcc26e475da7..2f5b4be252619d909fb3fa6843bd58ba288a57bf 100644 (file)
--- a/include/uapi/linux/nfc.h
+++ b/include/uapi/linux/nfc.h
@@ -164,6 +164,7 @@ enum nfc_commands {
  * @NFC_ATTR_VENDOR_SUBCMD: Vendor specific sub command
  * @NFC_ATTR_VENDOR_DATA: Vendor specific data, to be optionally passed
  *     to a vendor specific command implementation
+ * @NFC_ATTR_TARGET_ATS: ISO 14443 type A target Answer To Select
  */
 enum nfc_attrs {
        NFC_ATTR_UNSPEC,
@@ -198,6 +199,7 @@ enum nfc_attrs {
        NFC_ATTR_VENDOR_ID,
        NFC_ATTR_VENDOR_SUBCMD,
        NFC_ATTR_VENDOR_DATA,
+       NFC_ATTR_TARGET_ATS,
 /* private: internal use only */
        __NFC_ATTR_AFTER_LAST
 };
@@ -225,6 +227,7 @@ enum nfc_sdp_attr {
 #define NFC_GB_MAXSIZE                 48
 #define NFC_FIRMWARE_NAME_MAXSIZE      32
 #define NFC_ISO15693_UID_MAXSIZE       8
+#define NFC_ATS_MAXSIZE                        20
 
 /* NFC protocols */
 #define NFC_PROTO_JEWEL                1

diff --git a/net/nfc/nci/core.c b/net/nfc/nci/core.c
index f456a5911e7d1bc3e7bd08107c0ecace98f3df8e..1ec5955fe4692e3800ec1d892481421e7e135583 100644 (file)
--- a/net/nfc/nci/core.c
+++ b/net/nfc/nci/core.c
@@ -757,6 +757,14 @@ int nci_core_conn_close(struct nci_dev *ndev, u8 conn_id)
 }
 EXPORT_SYMBOL(nci_core_conn_close);
 
+static void nci_set_target_ats(struct nfc_target *target, struct nci_dev *ndev)
+{
+       if (ndev->target_ats_len > 0) {
+               target->ats_len = ndev->target_ats_len;
+               memcpy(target->ats, ndev->target_ats, target->ats_len);
+       }
+}
+
 static int nci_set_local_general_bytes(struct nfc_dev *nfc_dev)
 {
        struct nci_dev *ndev = nfc_get_drvdata(nfc_dev);
@@ -939,8 +947,11 @@ static int nci_activate_target(struct nfc_dev *nfc_dev,
                                 msecs_to_jiffies(NCI_RF_DISC_SELECT_TIMEOUT));
        }
 
-       if (!rc)
+       if (!rc) {
                ndev->target_active_prot = protocol;
+               if (protocol == NFC_PROTO_ISO14443)
+                       nci_set_target_ats(target, ndev);
+       }
 
        return rc;
 }

diff --git a/net/nfc/nci/ntf.c b/net/nfc/nci/ntf.c
index 994a0a1efb58900ad556023a4f367647a151875d..a818eff27e6bc2555a189d9dbbd82bd6ca39680d 100644 (file)
--- a/net/nfc/nci/ntf.c
+++ b/net/nfc/nci/ntf.c
@@ -402,7 +402,7 @@ static int nci_extract_activation_params_iso_dep(struct nci_dev *ndev,
        switch (ntf->activation_rf_tech_and_mode) {
        case NCI_NFC_A_PASSIVE_POLL_MODE:
                nfca_poll = &ntf->activation_params.nfca_poll_iso_dep;
-               nfca_poll->rats_res_len = min_t(__u8, *data++, 20);
+               nfca_poll->rats_res_len = min_t(__u8, *data++, NFC_ATS_MAXSIZE);
                pr_debug("rats_res_len %d\n", nfca_poll->rats_res_len);
                if (nfca_poll->rats_res_len > 0) {
                        memcpy(nfca_poll->rats_res,
@@ -531,6 +531,28 @@ static int nci_store_general_bytes_nfc_dep(struct nci_dev *ndev,
        return NCI_STATUS_OK;
 }
 
+static int nci_store_ats_nfc_iso_dep(struct nci_dev *ndev,
+                                    const struct nci_rf_intf_activated_ntf *ntf)
+{
+       ndev->target_ats_len = 0;
+
+       if (ntf->activation_params_len <= 0)
+               return NCI_STATUS_OK;
+
+       if (ntf->activation_params.nfca_poll_iso_dep.rats_res_len > NFC_ATS_MAXSIZE) {
+               pr_debug("ATS too long\n");
+               return NCI_STATUS_RF_PROTOCOL_ERROR;
+       }
+
+       if (ntf->activation_params.nfca_poll_iso_dep.rats_res_len > 0) {
+               ndev->target_ats_len = ntf->activation_params.nfca_poll_iso_dep.rats_res_len;
+               memcpy(ndev->target_ats, ntf->activation_params.nfca_poll_iso_dep.rats_res,
+                      ndev->target_ats_len);
+       }
+
+       return NCI_STATUS_OK;
+}
+
 static void nci_rf_intf_activated_ntf_packet(struct nci_dev *ndev,
                                             const struct sk_buff *skb)
 {
@@ -660,6 +682,14 @@ exit:
                        if (err != NCI_STATUS_OK)
                                pr_err("unable to store general bytes\n");
                }
+
+               /* store ATS to be reported later in nci_activate_target */
+               if (ntf.rf_interface == NCI_RF_INTERFACE_ISO_DEP &&
+                   ntf.activation_rf_tech_and_mode == NCI_NFC_A_PASSIVE_POLL_MODE) {
+                       err = nci_store_ats_nfc_iso_dep(ndev, &ntf);
+                       if (err != NCI_STATUS_OK)
+                               pr_err("unable to store ATS\n");
+               }
        }
 
        if (!(ntf.activation_rf_tech_and_mode & NCI_RF_TECH_MODE_LISTEN_MASK)) {

diff --git a/net/nfc/netlink.c b/net/nfc/netlink.c
index dd2ce73a24fbe766f8d947296a27ccc6d3a02c09..6a40b8d0350d944b05a36c2581ac7382b1c6cb7d 100644 (file)
--- a/net/nfc/netlink.c
+++ b/net/nfc/netlink.c
@@ -96,6 +96,11 @@ static int nfc_genl_send_target(struct sk_buff *msg, struct nfc_target *target,
                        goto nla_put_failure;
        }
 
+       if (target->ats_len > 0 &&
+           nla_put(msg, NFC_ATTR_TARGET_ATS, target->ats_len,
+                   target->ats))
+               goto nla_put_failure;
+
        genlmsg_end(msg, hdr);
        return 0;