NFC: digital: Enforce NFC-DEP PNI sequencing

NFC-DEP DEP_REQ and DEP_RES exchanges using 'I'
and 'ACK/NACK' PDUs have a sequence number called
the Packet Number Information (PNI).  The PNI
is incremented (modulo 4) after every DEP_REQ/
DEP_RES pair and should be verified by the digital
layer code.  That verification isn't always done,
though, so add code to make sure that it is done.

Reviewed-by: Thierry Escande <thierry.escande@linux.intel.com>
Tested-by: Thierry Escande <thierry.escande@linux.intel.com>
Signed-off-by: Mark A. Greer <mgreer@animalcreek.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

1 files changed, 33 insertions, 3 deletions

diff --git a/net/nfc/digital_dep.c b/net/nfc/digital_dep.c
index d5e669b0dedf..95a69898d5f5 100644
--- a/net/nfc/digital_dep.c
+++ b/net/nfc/digital_dep.c
@@ -447,8 +447,18 @@ static void digital_in_recv_dep_res(struct nfc_digital_dev *ddev, void *arg,
 
         case DIGITAL_NFC_DEP_PFB_ACK_NACK_PDU:
                 pr_err("Received a ACK/NACK PDU\n");
-                rc = -EIO;
-                goto error;
+
+                if (DIGITAL_NFC_DEP_PFB_PNI(pfb) != ddev->curr_nfc_dep_pni) {
+                        PROTOCOL_ERR("14.12.3.3");
+                        rc = -EIO;
+                        goto exit;
+                }
+
+                ddev->curr_nfc_dep_pni =
+                        DIGITAL_NFC_DEP_PFB_PNI(ddev->curr_nfc_dep_pni + 1);
+
+                rc = -EINVAL;
+                goto exit;
 
         case DIGITAL_NFC_DEP_PFB_SUPERVISOR_PDU:
                 if (!DIGITAL_NFC_DEP_PFB_IS_TIMEOUT(pfb)) {
@@ -592,9 +602,22 @@ static void digital_tg_recv_dep_req(struct nfc_digital_dev *ddev, void *arg,
         switch (DIGITAL_NFC_DEP_PFB_TYPE(pfb)) {
         case DIGITAL_NFC_DEP_PFB_I_PDU:
                 pr_debug("DIGITAL_NFC_DEP_PFB_I_PDU\n");
-                ddev->curr_nfc_dep_pni = DIGITAL_NFC_DEP_PFB_PNI(pfb);
+
+                if (DIGITAL_NFC_DEP_PFB_PNI(pfb) != ddev->curr_nfc_dep_pni) {
+                        PROTOCOL_ERR("14.12.3.4");
+                        rc = -EIO;
+                        goto exit;
+                }
+
+                rc = 0;
                 break;
         case DIGITAL_NFC_DEP_PFB_ACK_NACK_PDU:
+                if (DIGITAL_NFC_DEP_PFB_PNI(pfb) != ddev->curr_nfc_dep_pni) {
+                        PROTOCOL_ERR("14.12.3.4");
+                        rc = -EIO;
+                        goto exit;
+                }
+
                 pr_err("Received a ACK/NACK PDU\n");
                 rc = -EINVAL;
                 goto exit;
@@ -629,6 +652,9 @@ int digital_tg_send_dep_res(struct nfc_digital_dev *ddev, struct sk_buff *skb)
                        sizeof(ddev->did));
         }
 
+        ddev->curr_nfc_dep_pni =
+                DIGITAL_NFC_DEP_PFB_PNI(ddev->curr_nfc_dep_pni + 1);
+
         digital_skb_push_dep_sod(ddev, skb);
 
         ddev->skb_add_crc(skb);
@@ -677,6 +703,8 @@ static int digital_tg_send_psl_res(struct nfc_digital_dev *ddev, u8 did,
 
         ddev->skb_add_crc(skb);
 
+        ddev->curr_nfc_dep_pni = 0;
+
         rc = digital_tg_send_cmd(ddev, skb, 0, digital_tg_send_psl_res_complete,
                                  (void *)(unsigned long)rf_tech);
         if (rc)
@@ -800,6 +828,8 @@ static int digital_tg_send_atr_res(struct nfc_digital_dev *ddev,
 
         ddev->skb_add_crc(skb);
 
+        ddev->curr_nfc_dep_pni = 0;
+
         rc = digital_tg_send_cmd(ddev, skb, 999,
                                  digital_tg_send_atr_res_complete, NULL);
         if (rc)