summaryrefslogtreecommitdiffstats
path: root/src/boot/efi/vmm.c
blob: 0f268a1512b1bbccf3b0729c31d79dc10237921f (plain)
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
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
/* SPDX-License-Identifier: LGPL-2.1-or-later */

#if defined(__i386__) || defined(__x86_64__)
#  include <cpuid.h>
#endif

#include "confidential-virt-fundamental.h"
#include "device-path-util.h"
#include "drivers.h"
#include "efi-string.h"
#include "efivars.h"
#include "proto/device-path.h"
#include "string-util-fundamental.h"
#include "util.h"
#include "vmm.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;

        err = BS->HandleProtocol(device, MAKE_GUID_PTR(EFI_DEVICE_PATH_PROTOCOL), (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, MAKE_GUID_PTR(QEMU_KERNEL_LOADER_FS_MEDIA), sizeof(EFI_GUID)) == 0)
                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;
}

/*
 * 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, MAKE_GUID_PTR(EFI_SIMPLE_FILE_SYSTEM_PROTOCOL), NULL, &n_handles, &handles);
        if (err != EFI_SUCCESS)
                return err;

        for (size_t order = 0;; order++) {
                _cleanup_free_ EFI_DEVICE_PATH *dp = NULL;

                _cleanup_free_ char16_t *order_str = xasprintf("VMMBootOrder%04zx", order);
                dp_err = efivar_get_raw(MAKE_GUID_PTR(VMM_BOOT_ORDER), order_str, (void**) &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], MAKE_GUID_PTR(EFI_DEVICE_PATH_PROTOCOL), (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();
}

static bool cpuid_in_hypervisor(void) {
#if defined(__i386__) || defined(__x86_64__)
        unsigned eax, ebx, ecx, edx;

        /* This is a dumbed down version of src/basic/virt.c's detect_vm() that safely works in the UEFI
         * environment. */

        if (__get_cpuid(1, &eax, &ebx, &ecx, &edx) == 0)
                return false;

        if (FLAGS_SET(ecx, 0x80000000U))
                return true;
#endif

        return false;
}

#define SMBIOS_TABLE_GUID \
        GUID_DEF(0xeb9d2d31, 0x2d88, 0x11d3, 0x9a, 0x16, 0x00, 0x90, 0x27, 0x3f, 0xc1, 0x4d)
#define SMBIOS3_TABLE_GUID \
        GUID_DEF(0xf2fd1544, 0x9794, 0x4a2c, 0x99, 0x2e, 0xe5, 0xbb, 0xcf, 0x20, 0xe3, 0x94)

typedef struct {
        uint8_t anchor_string[4];
        uint8_t entry_point_structure_checksum;
        uint8_t entry_point_length;
        uint8_t major_version;
        uint8_t minor_version;
        uint16_t max_structure_size;
        uint8_t entry_point_revision;
        uint8_t formatted_area[5];
        uint8_t intermediate_anchor_string[5];
        uint8_t intermediate_checksum;
        uint16_t table_length;
        uint32_t table_address;
        uint16_t number_of_smbios_structures;
        uint8_t smbios_bcd_revision;
} _packed_ SmbiosEntryPoint;

typedef struct {
        uint8_t anchor_string[5];
        uint8_t entry_point_structure_checksum;
        uint8_t entry_point_length;
        uint8_t major_version;
        uint8_t minor_version;
        uint8_t docrev;
        uint8_t entry_point_revision;
        uint8_t reserved;
        uint32_t table_maximum_size;
        uint64_t table_address;
} _packed_ Smbios3EntryPoint;

typedef struct {
        uint8_t type;
        uint8_t length;
        uint8_t handle[2];
} _packed_ SmbiosHeader;

typedef struct {
        SmbiosHeader header;
        uint8_t vendor;
        uint8_t bios_version;
        uint16_t bios_segment;
        uint8_t bios_release_date;
        uint8_t bios_size;
        uint64_t bios_characteristics;
        uint8_t bios_characteristics_ext[2];
} _packed_ SmbiosTableType0;

typedef struct {
        SmbiosHeader header;
        uint8_t count;
        char contents[];
} _packed_ SmbiosTableType11;

static const void *find_smbios_configuration_table(uint64_t *ret_size) {
        assert(ret_size);

        const Smbios3EntryPoint *entry3 = find_configuration_table(MAKE_GUID_PTR(SMBIOS3_TABLE));
        if (entry3 && memcmp(entry3->anchor_string, "_SM3_", 5) == 0 &&
            entry3->entry_point_length <= sizeof(*entry3)) {
                *ret_size = entry3->table_maximum_size;
                return PHYSICAL_ADDRESS_TO_POINTER(entry3->table_address);
        }

        const SmbiosEntryPoint *entry = find_configuration_table(MAKE_GUID_PTR(SMBIOS_TABLE));
        if (entry && memcmp(entry->anchor_string, "_SM_", 4) == 0 &&
            entry->entry_point_length <= sizeof(*entry)) {
                *ret_size = entry->table_length;
                return PHYSICAL_ADDRESS_TO_POINTER(entry->table_address);
        }

        return NULL;
}

static const SmbiosHeader *get_smbios_table(uint8_t type, uint64_t *ret_size_left) {
        uint64_t size = 0;
        const uint8_t *p = find_smbios_configuration_table(&size);
        if (!p)
                return NULL;

        for (;;) {
                if (size < sizeof(SmbiosHeader))
                        return NULL;

                const SmbiosHeader *header = (const SmbiosHeader *) p;

                /* End of table. */
                if (header->type == 127)
                        return NULL;

                if (size < header->length)
                        return NULL;

                if (header->type == type) {
                        if (ret_size_left)
                                *ret_size_left = size;
                        return header; /* Yay! */
                }

                /* Skip over formatted area. */
                size -= header->length;
                p += header->length;

                /* Skip over string table. */
                for (;;) {
                        const uint8_t *e = memchr(p, 0, size);
                        if (!e)
                                return NULL;

                        if (e == p) {/* Double NUL byte means we've reached the end of the string table. */
                                p++;
                                size--;
                                break;
                        }

                        size -= e + 1 - p;
                        p = e + 1;
                }
        }

        return NULL;
}

static bool smbios_in_hypervisor(void) {
        /* Look up BIOS Information (Type 0). */
        const SmbiosTableType0 *type0 = (const SmbiosTableType0 *) get_smbios_table(0, NULL);
        if (!type0 || type0->header.length < sizeof(SmbiosTableType0))
                return false;

        /* Bit 4 of 2nd BIOS characteristics extension bytes indicates virtualization. */
        return FLAGS_SET(type0->bios_characteristics_ext[1], 1 << 4);
}

bool in_hypervisor(void) {
        static int cache = -1;
        if (cache >= 0)
                return cache;

        cache = cpuid_in_hypervisor() || smbios_in_hypervisor();
        return cache;
}

const char* smbios_find_oem_string(const char *name) {
        uint64_t left;

        assert(name);

        const SmbiosTableType11 *type11 = (const SmbiosTableType11 *) get_smbios_table(11, &left);
        if (!type11 || type11->header.length < sizeof(SmbiosTableType11))
                return NULL;

        assert(left >= type11->header.length);

        const char *s = type11->contents;
        left -= type11->header.length;

        for (const char *p = s; p < s + left; ) {
                const char *e = memchr(p, 0, s + left - p);
                if (!e || e == p) /* Double NUL byte means we've reached the end of the OEM strings. */
                        break;

                const char *eq = startswith8(p, name);
                if (eq && *eq == '=')
                        return eq + 1;

                p = e + 1;
        }

        return NULL;
}

#if defined(__i386__) || defined(__x86_64__)
static uint32_t cpuid_leaf(uint32_t eax, char ret_sig[static 13], bool swapped) {
        /* zero-init as some queries explicitly require subleaf == 0 */
        uint32_t sig[3] = {};

        if (swapped)
                __cpuid_count(eax, 0, eax, sig[0], sig[2], sig[1]);
        else
                __cpuid_count(eax, 0, eax, sig[0], sig[1], sig[2]);

        memcpy(ret_sig, sig, sizeof(sig));
        ret_sig[12] = 0; /* \0-terminate the string to make string comparison possible */

        return eax;
}

static uint64_t msr(uint32_t index) {
        uint64_t val;
#ifdef __x86_64__
        uint32_t low, high;
        asm volatile ("rdmsr" : "=a"(low), "=d"(high) : "c"(index) : "memory");
        val = ((uint64_t)high << 32) | low;
#else
        asm volatile ("rdmsr" : "=A"(val) : "c"(index) : "memory");
#endif
        return val;
}

static bool detect_hyperv_sev(void) {
        uint32_t eax, ebx, ecx, edx, feat;
        char sig[13] = {};

        feat = cpuid_leaf(CPUID_HYPERV_VENDOR_AND_MAX_FUNCTIONS, sig, false);

        if (feat < CPUID_HYPERV_MIN || feat > CPUID_HYPERV_MAX)
                return false;

        if (memcmp(sig, CPUID_SIG_HYPERV, sizeof(sig)) != 0)
                return false;

        __cpuid(CPUID_HYPERV_FEATURES, eax, ebx, ecx, edx);

        if (ebx & CPUID_HYPERV_ISOLATION && !(ebx & CPUID_HYPERV_CPU_MANAGEMENT)) {
                __cpuid(CPUID_HYPERV_ISOLATION_CONFIG, eax, ebx, ecx, edx);

                if ((ebx & CPUID_HYPERV_ISOLATION_TYPE_MASK) == CPUID_HYPERV_ISOLATION_TYPE_SNP)
                        return true;
        }

        return false;
}

static bool detect_sev(void) {
        uint32_t eax, ebx, ecx, edx;
        uint64_t msrval;

        __cpuid(CPUID_GET_HIGHEST_FUNCTION, eax, ebx, ecx, edx);

        if (eax < CPUID_AMD_GET_ENCRYPTED_MEMORY_CAPABILITIES)
                return false;

        __cpuid(CPUID_AMD_GET_ENCRYPTED_MEMORY_CAPABILITIES, eax, ebx, ecx, edx);

        /* bit 1 == CPU supports SEV feature
         *
         * Note, Azure blocks this CPUID leaf from its SEV-SNP
         * guests, so we must fallback to trying some HyperV
         * specific CPUID checks.
         */
        if (!(eax & EAX_SEV))
                return detect_hyperv_sev();

        msrval = msr(MSR_AMD64_SEV);

        if (msrval & (MSR_SEV_SNP | MSR_SEV_ES | MSR_SEV))
                return true;

        return false;
}

static bool detect_tdx(void) {
        uint32_t eax, ebx, ecx, edx;
        char sig[13] = {};

        __cpuid(CPUID_GET_HIGHEST_FUNCTION, eax, ebx, ecx, edx);

        if (eax < CPUID_INTEL_TDX_ENUMERATION)
                return false;

        cpuid_leaf(CPUID_INTEL_TDX_ENUMERATION, sig, true);

        if (memcmp(sig, CPUID_SIG_INTEL_TDX, sizeof(sig)) == 0)
                return true;

        return false;
}
#endif /* ! __i386__ && ! __x86_64__ */

bool is_confidential_vm(void) {
#if defined(__i386__) || defined(__x86_64__)
        char sig[13] = {};

        if (!cpuid_in_hypervisor())
                return false;

        cpuid_leaf(0, sig, true);

        if (memcmp(sig, CPUID_SIG_AMD, sizeof(sig)) == 0)
                return detect_sev();
        if (memcmp(sig, CPUID_SIG_INTEL, sizeof(sig)) == 0)
                return detect_tdx();
#endif /* ! __i386__ && ! __x86_64__ */

        return false;
}