Imlemented basic command handler and added memdump functionality

ShofEL2-for-T124/payloads/payload.c

@@ -17,20 +17,43 @@ int mystrlen(char *data) {
     return i-1;
 }
 
-#define usb_log(msg, error) usb_write(msg, mystrlen(msg), error);
+void usb_log(char * msg, uint32_t * error){
+    usb_write(msg, mystrlen(msg), error);
+}
+
+// #define usb_log(msg, error) usb_write(msg, mystrlen(msg), error);
 
 __attribute__((section(".init")))
 void payload_main() {
     uint32_t error_code;
-    uint32_t data = 0xdeadbeef;
-    u32 num_xfer;
-    u32 to_send;
+    uint32_t mem_off;
+    uint32_t mem_sz;
+    uint32_t blk_sz;
+    char data[12];
     u8 *buffer = (u8*)0x40020000;
-    uint32_t test = 1;
 
+    usb_log("cmd_handler", &error_code);
     while(1){
-        usb_write(&test, sizeof(test), &num_xfer );
-        test += 1;
+        usb_read(&data, 4, &error_code);
+        if(data[0] == 'M' && data[1] == 'E' && data[2] == 'M' && data[3] == 'D') {
+            usb_write(&data, 4, &error_code);
+            usb_read(&data, 8,&error_code); // Receive uint64_t size and and uint32_t offset
+            mem_off = *(uint32_t *)data;
+            mem_sz = *(uint32_t *)(data+4);
+            for(unsigned int i=0;i<mem_sz;i+=0x200) {
+                if((mem_sz - i) < 0x200) {
+                    blk_sz = mem_sz - i;
+                } else {
+                    blk_sz = 0x200;
+                }
+                usb_write((void *)(mem_off+i), blk_sz, &error_code);
+                usb_read(&data, 4, &error_code);
+                if(!(data[0] == 'A' && data[1] == 'C' && data[2] == 'K')) {
+                    break;
+                }
+            }
+        }
+        usb_log("done", &error_code);
     }
 }
 

exploit.py

@@ -10,6 +10,7 @@ import time
 import fcntl
 import platform
 import os
+from patches import *
 
 IS_OSX = platform.system() == "Darwin"
 USBDEVFS_URB_TYPE_CONTROL = 2
@@ -205,9 +206,60 @@ class TegraRCM():
         if(status == 0):
             error("wrong status returned!")
 
+    def send_verify_cmd(self, cmd):
+        self.dev.write(cmd)
+        r = self.dev.read(0x200)
+        if(r != cmd):
+            error(f"Error on sending command! {r}")
+            return False
+        return True
 
+    def handle_done(self):
+        r = self.dev.read(0x200)
+        if(r != b"done"):
+            error("Error on writing vbar!")
+
+    def memdump_region(self, offset, size):
+        if(not self.send_verify_cmd(b"MEMD")):
+            return
+        mem_param = struct.pack('<LL', offset, size)
+        self.dev.write(mem_param)
+        received = b''
+        blk_sz = 0x200
+        while len(received) < size:
+            if (remaining := size - len(received)) < 0x200:
+                blk_sz = remaining
+            d = self.dev.read(blk_sz)
+            if len(d) == blk_sz:
+                self.dev.write(b"ACK\x00")
+            received += d
+        self.handle_done()
+        return received
+
+    def search_bootrom(self):
+        dumped = BytesIO()
+        for i in range(0, 0x1000000, 0x10000):
+            d = self.memdump_region(i, 0x10000)
+            dumped.write(d)
+            if(cpsr_to_r0_ins in d or r1_to_cpsr in d):
+                info(f"Found cpsr instruction at {hex(i)}")
+            print(".", end="")
+        info(f"dumped {hex(len(dumped))} data")
+
+    def dump_bootrom(self):
+        d = self.memdump_region(0x100000, 0x1000)
+        if(True):
             pass
         
+    def cmd_handler(self):
+        while True:
+            cmd = self.dev.read(0x200)
+            if(cmd == b"cmd_handler"):
+                self.search_bootrom()
+                #dump memory
+                self.dump_bootrom()
+            
+
 if __name__ == "__main__":
     parser = argparse.ArgumentParser()
     parser.add_argument("payload", help="Payload to send to the tablet")
@@ -216,3 +268,4 @@ if __name__ == "__main__":
     rcm = TegraRCM()
     rcm.dev.read_chip_id()
     rcm.send_payload(args.payload)
+    rcm.cmd_handler()

patches.py

@@ -0,0 +1,13 @@
+from keystone import *
+from capstone import *
+from utils import *
+import io
+
+cs = Cs(CS_ARCH_ARM, CS_MODE_THUMB)
+ks = Ks(KS_ARCH_ARM, KS_MODE_THUMB)
+
+def ks_to_bytes(ks_code):
+    return b"".join([int.to_bytes(x, 1, "little") for x in ks_code[0]])
+
+cpsr_to_r0_ins = ks_to_bytes(ks.asm("mrs     r0, cpsr"))
+r1_to_cpsr = ks_to_bytes(ks.asm("msr     cpsr_c, r1"))