1 /*
2  * virtio-serial 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 "tests/qtest/libqtest.h"
16 #include "tests/qtest/libqos/virtio-scsi.h"
17 #include "tests/qtest/libqos/virtio.h"
18 #include "tests/qtest/libqos/virtio-pci.h"
19 #include "standard-headers/linux/virtio_ids.h"
20 #include "standard-headers/linux/virtio_pci.h"
21 #include "standard-headers/linux/virtio_scsi.h"
22 #include "fuzz.h"
23 #include "qos_fuzz.h"
24 
25 #define PCI_SLOT                0x02
26 #define PCI_FN                  0x00
27 #define QVIRTIO_SCSI_TIMEOUT_US (1 * 1000 * 1000)
28 
29 #define MAX_NUM_QUEUES 64
30 
31 /* Based on tests/virtio-scsi-test.c */
32 typedef struct {
33     int num_queues;
34     QVirtQueue *vq[MAX_NUM_QUEUES + 2];
35 } QVirtioSCSIQueues;
36 
37 static QVirtioSCSIQueues *qvirtio_scsi_init(QVirtioDevice *dev, uint64_t mask)
38 {
39     QVirtioSCSIQueues *vs;
40     uint64_t feat;
41     int i;
42 
43     vs = g_new0(QVirtioSCSIQueues, 1);
44 
45     feat = qvirtio_get_features(dev);
46     if (mask) {
47         feat &= ~QVIRTIO_F_BAD_FEATURE | mask;
48     } else {
49         feat &= ~(QVIRTIO_F_BAD_FEATURE | (1ull << VIRTIO_RING_F_EVENT_IDX));
50     }
51     qvirtio_set_features(dev, feat);
52 
53     vs->num_queues = qvirtio_config_readl(dev, 0);
54 
55     for (i = 0; i < vs->num_queues + 2; i++) {
56         vs->vq[i] = qvirtqueue_setup(dev, fuzz_qos_alloc, i);
57     }
58 
59     qvirtio_set_driver_ok(dev);
60 
61     return vs;
62 }
63 
64 static void virtio_scsi_fuzz(QTestState *s, QVirtioSCSIQueues* queues,
65         const unsigned char *Data, size_t Size)
66 {
67     /*
68      * Data is a sequence of random bytes. We split them up into "actions",
69      * followed by data:
70      * [vqa][dddddddd][vqa][dddd][vqa][dddddddddddd] ...
71      * The length of the data is specified by the preceding vqa.length
72      */
73     typedef struct vq_action {
74         uint8_t queue;
75         uint8_t length;
76         uint8_t write;
77         uint8_t next;
78         uint8_t kick;
79     } vq_action;
80 
81     /* Keep track of the free head for each queue we interact with */
82     bool vq_touched[MAX_NUM_QUEUES + 2] = {0};
83     uint32_t free_head[MAX_NUM_QUEUES + 2];
84 
85     QGuestAllocator *t_alloc = fuzz_qos_alloc;
86 
87     QVirtioSCSI *scsi = fuzz_qos_obj;
88     QVirtioDevice *dev = scsi->vdev;
89     QVirtQueue *q;
90     vq_action vqa;
91     while (Size >= sizeof(vqa)) {
92         /* Copy the action, so we can normalize length, queue and flags */
93         memcpy(&vqa, Data, sizeof(vqa));
94 
95         Data += sizeof(vqa);
96         Size -= sizeof(vqa);
97 
98         vqa.queue = vqa.queue % queues->num_queues;
99         /* Cap length at the number of remaining bytes in data */
100         vqa.length = vqa.length >= Size ? Size : vqa.length;
101         vqa.write = vqa.write & 1;
102         vqa.next = vqa.next & 1;
103         vqa.kick = vqa.kick & 1;
104 
105 
106         q = queues->vq[vqa.queue];
107 
108         /* Copy the data into ram, and place it on the virtqueue */
109         uint64_t req_addr = guest_alloc(t_alloc, vqa.length);
110         qtest_memwrite(s, req_addr, Data, vqa.length);
111         if (vq_touched[vqa.queue] == 0) {
112             vq_touched[vqa.queue] = 1;
113             free_head[vqa.queue] = qvirtqueue_add(s, q, req_addr, vqa.length,
114                     vqa.write, vqa.next);
115         } else {
116             qvirtqueue_add(s, q, req_addr, vqa.length, vqa.write , vqa.next);
117         }
118 
119         if (vqa.kick) {
120             qvirtqueue_kick(s, dev, q, free_head[vqa.queue]);
121             free_head[vqa.queue] = 0;
122         }
123         Data += vqa.length;
124         Size -= vqa.length;
125     }
126     /* In the end, kick each queue we interacted with */
127     for (int i = 0; i < MAX_NUM_QUEUES + 2; i++) {
128         if (vq_touched[i]) {
129             qvirtqueue_kick(s, dev, queues->vq[i], free_head[i]);
130         }
131     }
132 }
133 
134 static void virtio_scsi_with_flag_fuzz(QTestState *s,
135         const unsigned char *Data, size_t Size)
136 {
137     QVirtioSCSI *scsi = fuzz_qos_obj;
138     static QVirtioSCSIQueues *queues;
139 
140     if (Size >= sizeof(uint64_t)) {
141         queues = qvirtio_scsi_init(scsi->vdev, *(uint64_t *)Data);
142         virtio_scsi_fuzz(s, queues,
143                 Data + sizeof(uint64_t), Size - sizeof(uint64_t));
144         flush_events(s);
145     }
146     fuzz_reset(s);
147 }
148 
149 static void virtio_scsi_pre_fuzz(QTestState *s)
150 {
151     qos_init_path(s);
152 }
153 
154 static void *virtio_scsi_test_setup(GString *cmd_line, void *arg)
155 {
156     g_string_append(cmd_line,
157                     " -drive file=blkdebug::null-co://,"
158                     "file.image.read-zeroes=on,"
159                     "if=none,id=dr1,format=raw,file.align=4k "
160                     "-device scsi-hd,drive=dr1,lun=0,scsi-id=1");
161     return arg;
162 }
163 
164 
165 static void register_virtio_scsi_fuzz_targets(void)
166 {
167     fuzz_add_qos_target(&(FuzzTarget){
168                 .name = "virtio-scsi-flags-fuzz",
169                 .description = "Fuzz the virtio-scsi virtual queues. "
170                 "Also fuzzes the virtio flags",
171                 .pre_fuzz = &virtio_scsi_pre_fuzz,
172                 .fuzz = virtio_scsi_with_flag_fuzz,},
173                 "virtio-scsi",
174                 &(QOSGraphTestOptions){.before = virtio_scsi_test_setup}
175                 );
176 }
177 
178 fuzz_target_init(register_virtio_scsi_fuzz_targets);
179