Clean up packet size types and add some paranoia

None of this should fix an exploit, it's just healthy paranoia.

1 files changed, 26 insertions, 12 deletions

diff --git a/daemon/device.c b/daemon/device.c
index 7cda462..759cb91 100644
--- a/daemon/device.c
+++ b/daemon/device.c
@@ -38,7 +38,7 @@ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 
 int next_device_id;
 
-#define DEV_PKTBUF_SIZE 65536
+#define DEV_MRU 65536
 
 #define CONN_INBUF_SIZE         262144
 #define CONN_OUTBUF_SIZE        65536
@@ -90,13 +90,13 @@ struct mux_connection
         uint32_t tx_seq, tx_ack, tx_acked, tx_win;
         uint32_t rx_seq, rx_recvd, rx_ack, rx_win;
         int max_payload;
-        int sendable;
+        uint32_t sendable;
         int flags;
         unsigned char *ib_buf;
-        int ib_size;
-        int ib_capacity;
+        uint32_t ib_size;
+        uint32_t ib_capacity;
         unsigned char *ob_buf;
-        int ob_capacity;
+        uint32_t ob_capacity;
         short events;
         uint64_t last_ack_time;
 };
@@ -109,7 +109,7 @@ struct mux_device
         struct collection connections;
         uint16_t next_sport;
         unsigned char *pktbuf;
-        int pktlen;
+        uint32_t pktlen;
 };
 
 static struct collection device_list;
@@ -404,7 +404,7 @@ void device_client_process(int device_id, struct mux_client *client, short event
         update_connection(conn);
 }
 
-static void connection_device_input(struct mux_connection *conn, unsigned char *payload, int payload_length)
+static void connection_device_input(struct mux_connection *conn, unsigned char *payload, uint32_t payload_length)
 {
         if((conn->ib_size + payload_length) > conn->ib_capacity) {
                 usbmuxd_log(LL_ERROR, "Input buffer overflow on device %d connection %d->%d (space=%d, payload=%d)", conn->dev->id, conn->sport, conn->dport, conn->ib_capacity-conn->ib_size, payload_length);
@@ -459,7 +459,7 @@ static void device_version_input(struct mux_device *dev, struct version_header *
         client_device_add(&info);
 }
 
-static void device_tcp_input(struct mux_device *dev, struct tcphdr *th, unsigned char *payload, int payload_length)
+static void device_tcp_input(struct mux_device *dev, struct tcphdr *th, unsigned char *payload, uint32_t payload_length)
 {
         usbmuxd_log(LL_DEBUG, "[IN] dev=%d sport=%d dport=%d seq=%d ack=%d flags=0x%x window=%d[%d] len=%d",
                 dev->id, ntohs(th->th_sport), ntohs(th->th_dport), ntohl(th->th_seq), ntohl(th->th_ack), th->th_flags, ntohs(th->th_win) << 8, ntohs(th->th_win), payload_length);
@@ -531,7 +531,7 @@ static void device_tcp_input(struct mux_device *dev, struct tcphdr *th, unsigned
         }
 }
 
-void device_data_input(struct usb_device *usbdev, unsigned char *buffer, int length)
+void device_data_input(struct usb_device *usbdev, unsigned char *buffer, uint32_t length)
 {
         struct mux_device *dev = NULL;
         FOREACH(struct mux_device *tdev, &device_list) {
@@ -548,11 +548,17 @@ void device_data_input(struct usb_device *usbdev, unsigned char *buffer, int len
         if(!length)
                 return;
 
+        // sanity check (should never happen with current USB implementation)
+        if((length > USB_MRU) || (length > DEV_MRU)) {
+                usbmuxd_log(LL_ERROR, "Too much data received from USB (%d), file a bug", length);
+                return;
+        }
+
         usbmuxd_log(LL_SPEW, "Mux data input for device %p: %p len %d", dev, buffer, length);
 
         // handle broken up transfers
         if(dev->pktlen) {
-                if((length + dev->pktlen) > DEV_PKTBUF_SIZE) {
+                if((length + dev->pktlen) > DEV_MRU) {
                         usbmuxd_log(LL_ERROR, "Incoming split packet is too large (%d so far), dropping!", length + dev->pktlen);
                         dev->pktlen = 0;
                         return;
@@ -588,13 +594,21 @@ void device_data_input(struct usb_device *usbdev, unsigned char *buffer, int len
 
         struct tcphdr *th;
         unsigned char *payload;
-        int payload_length;
+        uint32_t payload_length;
 
         switch(ntohl(mhdr->protocol)) {
                 case MUX_PROTO_VERSION:
+                        if(length < (sizeof(struct mux_header) + sizeof(struct version_header))) {
+                                usbmuxd_log(LL_ERROR, "Incoming version packet is too small (%d)", length);
+                                return;
+                        }
                         device_version_input(dev, (struct version_header *)(mhdr+1));
                         break;
                 case MUX_PROTO_TCP:
+                        if(length < (sizeof(struct mux_header) + sizeof(struct tcphdr))) {
+                                usbmuxd_log(LL_ERROR, "Incoming TCP packet is too small (%d)", length);
+                                return;
+                        }
                         th = (struct tcphdr *)(mhdr+1);
                         payload = (unsigned char *)(th+1);
                         payload_length = length - sizeof(struct tcphdr) - sizeof(struct mux_header);
@@ -618,7 +632,7 @@ int device_add(struct usb_device *usbdev)
         dev->usbdev = usbdev;
         dev->state = MUXDEV_INIT;
         dev->next_sport = 1;
-        dev->pktbuf = malloc(DEV_PKTBUF_SIZE);
+        dev->pktbuf = malloc(DEV_MRU);
         dev->pktlen = 0;
         struct version_header vh;
         vh.major = htonl(1);