1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
|
/* SPDX-License-Identifier: LGPL-2.1-or-later */
#include <efi.h>
#include <efilib.h>
#include <stdbool.h>
#include "drivers.h"
#include "efi-string.h"
#include "string-util-fundamental.h"
#include "util.h"
#define QEMU_KERNEL_LOADER_FS_MEDIA_GUID \
{ 0x1428f772, 0xb64a, 0x441e, {0xb8, 0xc3, 0x9e, 0xbd, 0xd7, 0xf8, 0x93, 0xc7 }}
#define VMM_BOOT_ORDER_GUID \
{ 0x668f4529, 0x63d0, 0x4bb5, {0xb6, 0x5d, 0x6f, 0xbb, 0x9d, 0x36, 0xa4, 0x4a }}
/* detect direct boot */
bool is_direct_boot(EFI_HANDLE device) {
EFI_STATUS err;
VENDOR_DEVICE_PATH *dp; /* NB: Alignment of this structure might be quirky! */
err = BS->HandleProtocol(device, &DevicePathProtocol, (void **) &dp);
if (err != EFI_SUCCESS)
return false;
/* 'qemu -kernel systemd-bootx64.efi' */
if (dp->Header.Type == MEDIA_DEVICE_PATH &&
dp->Header.SubType == MEDIA_VENDOR_DP &&
memcmp(&dp->Guid, &(EFI_GUID)QEMU_KERNEL_LOADER_FS_MEDIA_GUID, sizeof(EFI_GUID)) == 0) /* Don't change to efi_guid_equal() because EFI device path objects are not necessarily aligned! */
return true;
/* loaded from firmware volume (sd-boot added to ovmf) */
if (dp->Header.Type == MEDIA_DEVICE_PATH &&
dp->Header.SubType == MEDIA_PIWG_FW_VOL_DP)
return true;
return false;
}
static bool device_path_startswith(const EFI_DEVICE_PATH *dp, const EFI_DEVICE_PATH *start) {
if (!start)
return true;
if (!dp)
return false;
for (;;) {
if (IsDevicePathEnd(start))
return true;
if (IsDevicePathEnd(dp))
return false;
size_t l1 = DevicePathNodeLength(start);
size_t l2 = DevicePathNodeLength(dp);
if (l1 != l2)
return false;
if (memcmp(dp, start, l1) != 0)
return false;
start = NextDevicePathNode(start);
dp = NextDevicePathNode(dp);
}
}
/*
* Try find ESP when not loaded from ESP
*
* Inspect all filesystems known to the firmware, try find the ESP. In case VMMBootOrderNNNN variables are
* present they are used to inspect the filesystems in the specified order. When nothing was found or the
* variables are not present the function will do one final search pass over all filesystems.
*
* Recent OVMF builds store the qemu boot order (as specified using the bootindex property on the qemu
* command line) in VMMBootOrderNNNN. The variables contain a device path.
*
* Example qemu command line:
* qemu -virtio-scsi-pci,addr=14.0 -device scsi-cd,scsi-id=4,bootindex=1
*
* Resulting variable:
* VMMBootOrder0000 = PciRoot(0x0)/Pci(0x14,0x0)/Scsi(0x4,0x0)
*/
EFI_STATUS vmm_open(EFI_HANDLE *ret_vmm_dev, EFI_FILE **ret_vmm_dir) {
_cleanup_free_ EFI_HANDLE *handles = NULL;
size_t n_handles;
EFI_STATUS err, dp_err;
assert(ret_vmm_dev);
assert(ret_vmm_dir);
/* Make sure all file systems have been initialized. Only do this in VMs as this is slow
* on some real firmwares. */
(void) reconnect_all_drivers();
/* find all file system handles */
err = BS->LocateHandleBuffer(ByProtocol, &FileSystemProtocol, NULL, &n_handles, &handles);
if (err != EFI_SUCCESS)
return err;
for (size_t order = 0;; order++) {
_cleanup_free_ EFI_DEVICE_PATH *dp = NULL;
char16_t order_str[STRLEN("VMMBootOrder") + 4 + 1];
SPrint(order_str, sizeof(order_str), u"VMMBootOrder%04x", order);
dp_err = efivar_get_raw(&(EFI_GUID)VMM_BOOT_ORDER_GUID, order_str, (char**)&dp, NULL);
for (size_t i = 0; i < n_handles; i++) {
_cleanup_(file_closep) EFI_FILE *root_dir = NULL, *efi_dir = NULL;
EFI_DEVICE_PATH *fs;
err = BS->HandleProtocol(handles[i], &DevicePathProtocol, (void **) &fs);
if (err != EFI_SUCCESS)
return err;
/* check against VMMBootOrderNNNN (if set) */
if (dp_err == EFI_SUCCESS && !device_path_startswith(fs, dp))
continue;
err = open_volume(handles[i], &root_dir);
if (err != EFI_SUCCESS)
continue;
/* simple ESP check */
err = root_dir->Open(root_dir, &efi_dir, (char16_t*) u"\\EFI",
EFI_FILE_MODE_READ,
EFI_FILE_READ_ONLY | EFI_FILE_DIRECTORY);
if (err != EFI_SUCCESS)
continue;
*ret_vmm_dev = handles[i];
*ret_vmm_dir = TAKE_PTR(root_dir);
return EFI_SUCCESS;
}
if (dp_err != EFI_SUCCESS)
return EFI_NOT_FOUND;
}
assert_not_reached();
}
|
