1 // Copyright © 2022 Intel Corporation 2 // 3 // SPDX-License-Identifier: Apache-2.0 4 5 #![no_main] 6 7 use libfuzzer_sys::fuzz_target; 8 use seccompiler::SeccompAction; 9 use std::fs::File; 10 use std::io::Write; 11 use std::os::unix::io::{AsRawFd, FromRawFd, RawFd}; 12 use std::sync::Arc; 13 use virtio_devices::{VirtioDevice, VirtioInterrupt, VirtioInterruptType}; 14 use virtio_queue::{Queue, QueueT}; 15 use vm_memory::{bitmap::AtomicBitmap, Bytes, GuestAddress, GuestMemoryAtomic}; 16 use vmm_sys_util::eventfd::{EventFd, EFD_NONBLOCK}; 17 18 type GuestMemoryMmap = vm_memory::GuestMemoryMmap<AtomicBitmap>; 19 20 macro_rules! align { 21 ($n:expr, $align:expr) => {{ 22 (($n + $align - 1) / $align) * $align 23 }}; 24 } 25 26 const CONSOLE_INPUT_SIZE: usize = 128; 27 const QUEUE_DATA_SIZE: usize = 4; 28 const MEM_SIZE: usize = 32 * 1024 * 1024; 29 // Guest memory gap 30 const GUEST_MEM_GAP: u64 = 1 * 1024 * 1024; 31 // Guest physical address for the first virt queue 32 const BASE_VIRT_QUEUE_ADDR: u64 = MEM_SIZE as u64 + GUEST_MEM_GAP; 33 // Number of queues 34 const QUEUE_NUM: usize = 2; 35 // Max entries in the queue. 36 const QUEUE_SIZE: u16 = 256; 37 // Descriptor table alignment 38 const DESC_TABLE_ALIGN_SIZE: u64 = 16; 39 // Used ring alignment 40 const USED_RING_ALIGN_SIZE: u64 = 4; 41 // Descriptor table size 42 const DESC_TABLE_SIZE: u64 = 16_u64 * QUEUE_SIZE as u64; 43 // Available ring size 44 const AVAIL_RING_SIZE: u64 = 6_u64 + 2 * QUEUE_SIZE as u64; 45 // Padding size before used ring 46 const PADDING_SIZE: u64 = align!(AVAIL_RING_SIZE, USED_RING_ALIGN_SIZE) - AVAIL_RING_SIZE; 47 // Used ring size 48 const USED_RING_SIZE: u64 = 6_u64 + 8 * QUEUE_SIZE as u64; 49 // Virtio-queue size in bytes 50 const QUEUE_BYTES_SIZE: usize = align!( 51 DESC_TABLE_SIZE + AVAIL_RING_SIZE + PADDING_SIZE + USED_RING_SIZE, 52 DESC_TABLE_ALIGN_SIZE 53 ) as usize; 54 55 fuzz_target!(|bytes| { 56 if bytes.len() < (QUEUE_DATA_SIZE + QUEUE_BYTES_SIZE) * QUEUE_NUM + CONSOLE_INPUT_SIZE 57 || bytes.len() 58 > (QUEUE_DATA_SIZE + QUEUE_BYTES_SIZE) * QUEUE_NUM + CONSOLE_INPUT_SIZE + MEM_SIZE 59 { 60 return; 61 } 62 63 let (pipe_rx, mut pipe_tx) = create_pipe().unwrap(); 64 let output = unsafe { 65 File::from_raw_fd( 66 memfd_create(&std::ffi::CString::new("fuzz_console_output").unwrap()).unwrap(), 67 ) 68 }; 69 let endpoint = virtio_devices::Endpoint::FilePair(output, pipe_rx); 70 71 let (mut console, _) = virtio_devices::Console::new( 72 "fuzzer_console".to_owned(), 73 endpoint, 74 None, // resize_pipe 75 false, // iommu 76 SeccompAction::Allow, 77 EventFd::new(EFD_NONBLOCK).unwrap(), 78 None, 79 ) 80 .unwrap(); 81 82 let console_input_bytes = &bytes[..CONSOLE_INPUT_SIZE]; 83 let queue_data = &bytes[CONSOLE_INPUT_SIZE..CONSOLE_INPUT_SIZE + QUEUE_DATA_SIZE * QUEUE_NUM]; 84 let queue_bytes = &bytes[CONSOLE_INPUT_SIZE + QUEUE_DATA_SIZE * QUEUE_NUM 85 ..CONSOLE_INPUT_SIZE + (QUEUE_DATA_SIZE + QUEUE_BYTES_SIZE) * QUEUE_NUM]; 86 let mem_bytes = &bytes[CONSOLE_INPUT_SIZE + (QUEUE_DATA_SIZE + QUEUE_BYTES_SIZE) * QUEUE_NUM..]; 87 88 // Setup the virt queues with the input bytes 89 let mut queues = setup_virt_queues( 90 &[ 91 &queue_data[..QUEUE_DATA_SIZE].try_into().unwrap(), 92 &queue_data[QUEUE_DATA_SIZE..QUEUE_DATA_SIZE * 2] 93 .try_into() 94 .unwrap(), 95 ], 96 BASE_VIRT_QUEUE_ADDR, 97 ); 98 99 // Setup the guest memory with the input bytes 100 let mem = GuestMemoryMmap::from_ranges(&[ 101 (GuestAddress(0), MEM_SIZE), 102 (GuestAddress(BASE_VIRT_QUEUE_ADDR), queue_bytes.len()), 103 ]) 104 .unwrap(); 105 if mem 106 .write_slice(queue_bytes, GuestAddress(BASE_VIRT_QUEUE_ADDR)) 107 .is_err() 108 { 109 return; 110 } 111 if mem.write_slice(mem_bytes, GuestAddress(0 as u64)).is_err() { 112 return; 113 } 114 let guest_memory = GuestMemoryAtomic::new(mem); 115 116 let input_queue = queues.remove(0); 117 let input_evt = EventFd::new(0).unwrap(); 118 let input_queue_evt = unsafe { EventFd::from_raw_fd(libc::dup(input_evt.as_raw_fd())) }; 119 let output_queue = queues.remove(0); 120 let output_evt = EventFd::new(0).unwrap(); 121 let output_queue_evt = unsafe { EventFd::from_raw_fd(libc::dup(output_evt.as_raw_fd())) }; 122 123 // Kick the 'queue' events and endpoint event before activate the console device 124 input_queue_evt.write(1).unwrap(); 125 output_queue_evt.write(1).unwrap(); 126 pipe_tx.write_all(console_input_bytes).unwrap(); // To use fuzzed data; 127 128 console 129 .activate( 130 guest_memory, 131 Arc::new(NoopVirtioInterrupt {}), 132 vec![(0, input_queue, input_evt), (1, output_queue, output_evt)], 133 ) 134 .unwrap(); 135 136 // Wait for the events to finish and console device worker thread to return 137 console.wait_for_epoll_threads(); 138 }); 139 140 pub struct NoopVirtioInterrupt {} 141 142 impl VirtioInterrupt for NoopVirtioInterrupt { 143 fn trigger(&self, _int_type: VirtioInterruptType) -> std::result::Result<(), std::io::Error> { 144 Ok(()) 145 } 146 } 147 148 fn setup_virt_queues(bytes: &[&[u8; QUEUE_DATA_SIZE]], base_addr: u64) -> Vec<Queue> { 149 let mut queues = Vec::new(); 150 for (i, b) in bytes.iter().enumerate() { 151 let mut q = Queue::new(QUEUE_SIZE).unwrap(); 152 153 let desc_table_addr = base_addr + (QUEUE_BYTES_SIZE * i) as u64; 154 let avail_ring_addr = desc_table_addr + DESC_TABLE_SIZE; 155 let used_ring_addr = avail_ring_addr + PADDING_SIZE + AVAIL_RING_SIZE; 156 q.try_set_desc_table_address(GuestAddress(desc_table_addr)) 157 .unwrap(); 158 q.try_set_avail_ring_address(GuestAddress(avail_ring_addr)) 159 .unwrap(); 160 q.try_set_used_ring_address(GuestAddress(used_ring_addr)) 161 .unwrap(); 162 163 q.set_next_avail(b[0] as u16); // 'u8' is enough given the 'QUEUE_SIZE' is small 164 q.set_next_used(b[1] as u16); 165 q.set_event_idx(b[2] % 2 != 0); 166 q.set_size(b[3] as u16 % QUEUE_SIZE); 167 168 q.set_ready(true); 169 queues.push(q); 170 } 171 172 queues 173 } 174 175 fn memfd_create(name: &std::ffi::CStr) -> Result<RawFd, std::io::Error> { 176 let res = unsafe { libc::syscall(libc::SYS_memfd_create, name.as_ptr(), 0) }; 177 178 if res < 0 { 179 Err(std::io::Error::last_os_error()) 180 } else { 181 Ok(res as RawFd) 182 } 183 } 184 185 fn create_pipe() -> Result<(File, File), std::io::Error> { 186 let mut pipe = [-1; 2]; 187 if unsafe { libc::pipe2(pipe.as_mut_ptr(), libc::O_CLOEXEC) } == -1 { 188 return Err(std::io::Error::last_os_error()); 189 } 190 let rx = unsafe { File::from_raw_fd(pipe[0]) }; 191 let tx = unsafe { File::from_raw_fd(pipe[1]) }; 192 193 Ok((rx, tx)) 194 } 195