1 /*
2  * virtio-net Fuzzing Target
3  *
4  * Copyright Red Hat Inc., 2019
5  *
6  * Authors:
7  *  Alexander Bulekov   <alxndr@bu.edu>
8  *
9  * This work is licensed under the terms of the GNU GPL, version 2 or later.
10  * See the COPYING file in the top-level directory.
11  */
12 
13 #include "qemu/osdep.h"
14 
15 #include "standard-headers/linux/virtio_config.h"
16 #include "tests/qtest/libqtest.h"
17 #include "tests/qtest/libqos/virtio-net.h"
18 #include "fuzz.h"
19 #include "fork_fuzz.h"
20 #include "qos_fuzz.h"
21 
22 
23 #define QVIRTIO_NET_TIMEOUT_US (30 * 1000 * 1000)
24 #define QVIRTIO_RX_VQ 0
25 #define QVIRTIO_TX_VQ 1
26 #define QVIRTIO_CTRL_VQ 2
27 
28 static int sockfds[2];
29 static bool sockfds_initialized;
30 
31 static void virtio_net_fuzz_multi(QTestState *s,
32         const unsigned char *Data, size_t Size, bool check_used)
33 {
34     typedef struct vq_action {
35         uint8_t queue;
36         uint8_t length;
37         uint8_t write;
38         uint8_t next;
39         uint8_t rx;
40     } vq_action;
41 
42     uint32_t free_head = 0;
43 
44     QGuestAllocator *t_alloc = fuzz_qos_alloc;
45 
46     QVirtioNet *net_if = fuzz_qos_obj;
47     QVirtioDevice *dev = net_if->vdev;
48     QVirtQueue *q;
49     vq_action vqa;
50     while (Size >= sizeof(vqa)) {
51         memcpy(&vqa, Data, sizeof(vqa));
52         Data += sizeof(vqa);
53         Size -= sizeof(vqa);
54 
55         q = net_if->queues[vqa.queue % 3];
56 
57         vqa.length = vqa.length >= Size ? Size :  vqa.length;
58 
59         /*
60          * Only attempt to write incoming packets, when using the socket
61          * backend. Otherwise, always place the input on a virtqueue.
62          */
63         if (vqa.rx && sockfds_initialized) {
64             write(sockfds[0], Data, vqa.length);
65         } else {
66             vqa.rx = 0;
67             uint64_t req_addr = guest_alloc(t_alloc, vqa.length);
68             /*
69              * If checking used ring, ensure that the fuzzer doesn't trigger
70              * trivial asserion failure on zero-zied buffer
71              */
72             qtest_memwrite(s, req_addr, Data, vqa.length);
73 
74 
75             free_head = qvirtqueue_add(s, q, req_addr, vqa.length,
76                     vqa.write, vqa.next);
77             qvirtqueue_add(s, q, req_addr, vqa.length, vqa.write , vqa.next);
78             qvirtqueue_kick(s, dev, q, free_head);
79         }
80 
81         /* Run the main loop */
82         qtest_clock_step(s, 100);
83         flush_events(s);
84 
85         /* Wait on used descriptors */
86         if (check_used && !vqa.rx) {
87             gint64 start_time = g_get_monotonic_time();
88             /*
89              * normally, we could just use qvirtio_wait_used_elem, but since we
90              * must manually run the main-loop for all the bhs to run, we use
91              * this hack with flush_events(), to run the main_loop
92              */
93             while (!vqa.rx && q != net_if->queues[QVIRTIO_RX_VQ]) {
94                 uint32_t got_desc_idx;
95                 /* Input led to a virtio_error */
96                 if (dev->bus->get_status(dev) & VIRTIO_CONFIG_S_NEEDS_RESET) {
97                     break;
98                 }
99                 if (dev->bus->get_queue_isr_status(dev, q) &&
100                         qvirtqueue_get_buf(s, q, &got_desc_idx, NULL)) {
101                     g_assert_cmpint(got_desc_idx, ==, free_head);
102                     break;
103                 }
104                 g_assert(g_get_monotonic_time() - start_time
105                         <= QVIRTIO_NET_TIMEOUT_US);
106 
107                 /* Run the main loop */
108                 qtest_clock_step(s, 100);
109                 flush_events(s);
110             }
111         }
112         Data += vqa.length;
113         Size -= vqa.length;
114     }
115 }
116 
117 static void virtio_net_fork_fuzz(QTestState *s,
118         const unsigned char *Data, size_t Size)
119 {
120     if (fork() == 0) {
121         virtio_net_fuzz_multi(s, Data, Size, false);
122         flush_events(s);
123         _Exit(0);
124     } else {
125         flush_events(s);
126         wait(NULL);
127     }
128 }
129 
130 static void virtio_net_fork_fuzz_check_used(QTestState *s,
131         const unsigned char *Data, size_t Size)
132 {
133     if (fork() == 0) {
134         virtio_net_fuzz_multi(s, Data, Size, true);
135         flush_events(s);
136         _Exit(0);
137     } else {
138         flush_events(s);
139         wait(NULL);
140     }
141 }
142 
143 static void virtio_net_pre_fuzz(QTestState *s)
144 {
145     qos_init_path(s);
146     counter_shm_init();
147 }
148 
149 static void *virtio_net_test_setup_socket(GString *cmd_line, void *arg)
150 {
151     int ret = socketpair(PF_UNIX, SOCK_STREAM, 0, sockfds);
152     g_assert_cmpint(ret, !=, -1);
153     fcntl(sockfds[0], F_SETFL, O_NONBLOCK);
154     sockfds_initialized = true;
155     g_string_append_printf(cmd_line, " -netdev socket,fd=%d,id=hs0 ",
156                            sockfds[1]);
157     return arg;
158 }
159 
160 static void *virtio_net_test_setup_user(GString *cmd_line, void *arg)
161 {
162     g_string_append_printf(cmd_line, " -netdev user,id=hs0 ");
163     return arg;
164 }
165 
166 static void register_virtio_net_fuzz_targets(void)
167 {
168     fuzz_add_qos_target(&(FuzzTarget){
169             .name = "virtio-net-socket",
170             .description = "Fuzz the virtio-net virtual queues. Fuzz incoming "
171             "traffic using the socket backend",
172             .pre_fuzz = &virtio_net_pre_fuzz,
173             .fuzz = virtio_net_fork_fuzz,},
174             "virtio-net",
175             &(QOSGraphTestOptions){.before = virtio_net_test_setup_socket}
176             );
177 
178     fuzz_add_qos_target(&(FuzzTarget){
179             .name = "virtio-net-socket-check-used",
180             .description = "Fuzz the virtio-net virtual queues. Wait for the "
181             "descriptors to be used. Timeout may indicate improperly handled "
182             "input",
183             .pre_fuzz = &virtio_net_pre_fuzz,
184             .fuzz = virtio_net_fork_fuzz_check_used,},
185             "virtio-net",
186             &(QOSGraphTestOptions){.before = virtio_net_test_setup_socket}
187             );
188     fuzz_add_qos_target(&(FuzzTarget){
189             .name = "virtio-net-slirp",
190             .description = "Fuzz the virtio-net virtual queues with the slirp "
191             " backend. Warning: May result in network traffic emitted from the "
192             " process. Run in an isolated network environment.",
193             .pre_fuzz = &virtio_net_pre_fuzz,
194             .fuzz = virtio_net_fork_fuzz,},
195             "virtio-net",
196             &(QOSGraphTestOptions){.before = virtio_net_test_setup_user}
197             );
198 }
199 
200 fuzz_target_init(register_virtio_net_fuzz_targets);
201