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qemu/hw/core/eif.c
Paolo Bonzini b7e55bd9d0 eif: cope with huge section sizes 
Check for overflow as well as allocation failure.  Resolves Coverity CID 1564859.

Reviewed-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>
Reviewed-by: Dorjoy Chowdhury <dorjoychy111@gmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2024-11-09 08:34:00 +01:00

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22 KiB
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/*
* EIF (Enclave Image Format) related helpers
*
* Copyright (c) 2024 Dorjoy Chowdhury <dorjoychy111@gmail.com>
*
* This work is licensed under the terms of the GNU GPL, version 2 or
* (at your option) any later version. See the COPYING file in the
* top-level directory.
*/
#include "qemu/osdep.h"
#include "qemu/bswap.h"
#include "qapi/error.h"
#include "crypto/hash.h"
#include "crypto/x509-utils.h"
#include <zlib.h> /* for crc32 */
#include <cbor.h>
#include "hw/core/eif.h"
#define MAX_SECTIONS 32
/* members are ordered according to field order in .eif file */
typedef struct EifHeader {
uint8_t magic[4]; /* must be .eif in ascii i.e., [46, 101, 105, 102] */
uint16_t version;
uint16_t flags;
uint64_t default_memory;
uint64_t default_cpus;
uint16_t reserved;
uint16_t section_cnt;
uint64_t section_offsets[MAX_SECTIONS];
uint64_t section_sizes[MAX_SECTIONS];
uint32_t unused;
uint32_t eif_crc32;
} QEMU_PACKED EifHeader;
/* members are ordered according to field order in .eif file */
typedef struct EifSectionHeader {
/*
* 0 = invalid, 1 = kernel, 2 = cmdline, 3 = ramdisk, 4 = signature,
* 5 = metadata
*/
uint16_t section_type;
uint16_t flags;
uint64_t section_size;
} QEMU_PACKED EifSectionHeader;
enum EifSectionTypes {
EIF_SECTION_INVALID = 0,
EIF_SECTION_KERNEL = 1,
EIF_SECTION_CMDLINE = 2,
EIF_SECTION_RAMDISK = 3,
EIF_SECTION_SIGNATURE = 4,
EIF_SECTION_METADATA = 5,
EIF_SECTION_MAX = 6,
};
static const char *section_type_to_string(uint16_t type)
{
const char *str;
switch (type) {
case EIF_SECTION_INVALID:
str = "invalid";
break;
case EIF_SECTION_KERNEL:
str = "kernel";
break;
case EIF_SECTION_CMDLINE:
str = "cmdline";
break;
case EIF_SECTION_RAMDISK:
str = "ramdisk";
break;
case EIF_SECTION_SIGNATURE:
str = "signature";
break;
case EIF_SECTION_METADATA:
str = "metadata";
break;
default:
str = "unknown";
break;
}
return str;
}
static bool read_eif_header(FILE *f, EifHeader *header, uint32_t *crc,
Error **errp)
{
size_t got;
size_t header_size = sizeof(*header);
got = fread(header, 1, header_size, f);
if (got != header_size) {
error_setg(errp, "Failed to read EIF header");
return false;
}
if (memcmp(header->magic, ".eif", 4) != 0) {
error_setg(errp, "Invalid EIF image. Magic mismatch.");
return false;
}
/* Exclude header->eif_crc32 field from CRC calculation */
*crc = crc32(*crc, (uint8_t *)header, header_size - 4);
header->version = be16_to_cpu(header->version);
header->flags = be16_to_cpu(header->flags);
header->default_memory = be64_to_cpu(header->default_memory);
header->default_cpus = be64_to_cpu(header->default_cpus);
header->reserved = be16_to_cpu(header->reserved);
header->section_cnt = be16_to_cpu(header->section_cnt);
for (int i = 0; i < MAX_SECTIONS; ++i) {
header->section_offsets[i] = be64_to_cpu(header->section_offsets[i]);
}
for (int i = 0; i < MAX_SECTIONS; ++i) {
header->section_sizes[i] = be64_to_cpu(header->section_sizes[i]);
if (header->section_sizes[i] > SSIZE_MAX) {
error_setg(errp, "Invalid EIF image. Section size out of bounds");
return false;
}
}
header->unused = be32_to_cpu(header->unused);
header->eif_crc32 = be32_to_cpu(header->eif_crc32);
return true;
}
static bool read_eif_section_header(FILE *f, EifSectionHeader *section_header,
uint32_t *crc, Error **errp)
{
size_t got;
size_t section_header_size = sizeof(*section_header);
got = fread(section_header, 1, section_header_size, f);
if (got != section_header_size) {
error_setg(errp, "Failed to read EIF section header");
return false;
}
*crc = crc32(*crc, (uint8_t *)section_header, section_header_size);
section_header->section_type = be16_to_cpu(section_header->section_type);
section_header->flags = be16_to_cpu(section_header->flags);
section_header->section_size = be64_to_cpu(section_header->section_size);
return true;
}
/*
* Upon success, the caller is responsible for unlinking and freeing *tmp_path.
*/
static bool get_tmp_file(const char *template, char **tmp_path, Error **errp)
{
int tmp_fd;
*tmp_path = NULL;
tmp_fd = g_file_open_tmp(template, tmp_path, NULL);
if (tmp_fd < 0 || *tmp_path == NULL) {
error_setg(errp, "Failed to create temporary file for template %s",
template);
return false;
}
close(tmp_fd);
return true;
}
static void safe_fclose(FILE *f)
{
if (f) {
fclose(f);
}
}
static void safe_unlink(char *f)
{
if (f) {
unlink(f);
}
}
/*
* Upon success, the caller is reponsible for unlinking and freeing *kernel_path
*/
static bool read_eif_kernel(FILE *f, uint64_t size, char **kernel_path,
uint8_t *kernel, uint32_t *crc, Error **errp)
{
size_t got;
FILE *tmp_file = NULL;
*kernel_path = NULL;
if (!get_tmp_file("eif-kernel-XXXXXX", kernel_path, errp)) {
goto cleanup;
}
tmp_file = fopen(*kernel_path, "wb");
if (tmp_file == NULL) {
error_setg_errno(errp, errno, "Failed to open temporary file %s",
*kernel_path);
goto cleanup;
}
got = fread(kernel, 1, size, f);
if ((uint64_t) got != size) {
error_setg(errp, "Failed to read EIF kernel section data");
goto cleanup;
}
got = fwrite(kernel, 1, size, tmp_file);
if ((uint64_t) got != size) {
error_setg(errp, "Failed to write EIF kernel section data to temporary"
" file");
goto cleanup;
}
*crc = crc32(*crc, kernel, size);
fclose(tmp_file);
return true;
cleanup:
safe_fclose(tmp_file);
safe_unlink(*kernel_path);
g_free(*kernel_path);
*kernel_path = NULL;
return false;
}
static bool read_eif_cmdline(FILE *f, uint64_t size, char *cmdline,
uint32_t *crc, Error **errp)
{
size_t got = fread(cmdline, 1, size, f);
if ((uint64_t) got != size) {
error_setg(errp, "Failed to read EIF cmdline section data");
return false;
}
*crc = crc32(*crc, (uint8_t *)cmdline, size);
return true;
}
static bool read_eif_ramdisk(FILE *eif, FILE *initrd, uint64_t size,
uint8_t *ramdisk, uint32_t *crc, Error **errp)
{
size_t got;
got = fread(ramdisk, 1, size, eif);
if ((uint64_t) got != size) {
error_setg(errp, "Failed to read EIF ramdisk section data");
return false;
}
got = fwrite(ramdisk, 1, size, initrd);
if ((uint64_t) got != size) {
error_setg(errp, "Failed to write EIF ramdisk data to temporary file");
return false;
}
*crc = crc32(*crc, ramdisk, size);
return true;
}
static bool get_signature_fingerprint_sha384(FILE *eif, uint64_t size,
uint8_t *sha384,
uint32_t *crc,
Error **errp)
{
size_t got;
g_autofree uint8_t *sig = NULL;
g_autofree uint8_t *cert = NULL;
cbor_item_t *item = NULL;
cbor_item_t *pcr0 = NULL;
size_t len;
size_t hash_len = QCRYPTO_HASH_DIGEST_LEN_SHA384;
struct cbor_pair *pair;
struct cbor_load_result result;
bool ret = false;
sig = g_try_malloc(size);
if (!sig) {
error_setg(errp, "Out of memory reading signature section");
goto cleanup;
}
got = fread(sig, 1, size, eif);
if ((uint64_t) got != size) {
error_setg(errp, "Failed to read EIF signature section data");
goto cleanup;
}
*crc = crc32(*crc, sig, size);
item = cbor_load(sig, size, &result);
if (!item || result.error.code != CBOR_ERR_NONE) {
error_setg(errp, "Failed to load signature section data as CBOR");
goto cleanup;
}
if (!cbor_isa_array(item) || cbor_array_size(item) < 1) {
error_setg(errp, "Invalid signature CBOR");
goto cleanup;
}
pcr0 = cbor_array_get(item, 0);
if (!pcr0) {
error_setg(errp, "Failed to get PCR0 signature");
goto cleanup;
}
if (!cbor_isa_map(pcr0) || cbor_map_size(pcr0) != 2) {
error_setg(errp, "Invalid signature CBOR");
goto cleanup;
}
pair = cbor_map_handle(pcr0);
if (!cbor_isa_string(pair->key) || cbor_string_length(pair->key) != 19 ||
memcmp(cbor_string_handle(pair->key), "signing_certificate", 19) != 0) {
error_setg(errp, "Invalid signautre CBOR");
goto cleanup;
}
if (!cbor_isa_array(pair->value)) {
error_setg(errp, "Invalid signature CBOR");
goto cleanup;
}
len = cbor_array_size(pair->value);
if (len == 0) {
error_setg(errp, "Invalid signature CBOR");
goto cleanup;
}
cert = g_try_malloc(len);
if (!cert) {
error_setg(errp, "Out of memory reading signature section");
goto cleanup;
}
for (int i = 0; i < len; ++i) {
cbor_item_t *tmp = cbor_array_get(pair->value, i);
if (!tmp) {
error_setg(errp, "Invalid signature CBOR");
goto cleanup;
}
if (!cbor_isa_uint(tmp) || cbor_int_get_width(tmp) != CBOR_INT_8) {
cbor_decref(&tmp);
error_setg(errp, "Invalid signature CBOR");
goto cleanup;
}
cert[i] = cbor_get_uint8(tmp);
cbor_decref(&tmp);
}
if (qcrypto_get_x509_cert_fingerprint(cert, len, QCRYPTO_HASH_ALGO_SHA384,
sha384, &hash_len, errp)) {
goto cleanup;
}
ret = true;
cleanup:
if (pcr0) {
cbor_decref(&pcr0);
}
if (item) {
cbor_decref(&item);
}
return ret;
}
/* Expects file to have offset 0 before this function is called */
static long get_file_size(FILE *f, Error **errp)
{
long size;
if (fseek(f, 0, SEEK_END) != 0) {
error_setg_errno(errp, errno, "Failed to seek to the end of file");
return -1;
}
size = ftell(f);
if (size == -1) {
error_setg_errno(errp, errno, "Failed to get offset");
return -1;
}
if (fseek(f, 0, SEEK_SET) != 0) {
error_setg_errno(errp, errno, "Failed to seek back to the start");
return -1;
}
return size;
}
static bool get_SHA384_digest(GList *list, uint8_t *digest, Error **errp)
{
size_t digest_len = QCRYPTO_HASH_DIGEST_LEN_SHA384;
size_t list_len = g_list_length(list);
struct iovec *iovec_list = g_new0(struct iovec, list_len);
bool ret = true;
GList *l;
int i;
for (i = 0, l = list; l != NULL; l = l->next, i++) {
iovec_list[i] = *(struct iovec *) l->data;
}
if (qcrypto_hash_bytesv(QCRYPTO_HASH_ALGO_SHA384, iovec_list, list_len,
&digest, &digest_len, errp) < 0) {
ret = false;
}
g_free(iovec_list);
return ret;
}
static void free_iovec(struct iovec *iov)
{
if (iov) {
g_free(iov->iov_base);
g_free(iov);
}
}
/*
* Upon success, the caller is reponsible for unlinking and freeing
* *kernel_path, *initrd_path and freeing *cmdline.
*/
bool read_eif_file(const char *eif_path, const char *machine_initrd,
char **kernel_path, char **initrd_path, char **cmdline,
uint8_t *image_sha384, uint8_t *bootstrap_sha384,
uint8_t *app_sha384, uint8_t *fingerprint_sha384,
bool *signature_found, Error **errp)
{
FILE *f = NULL;
FILE *machine_initrd_f = NULL;
FILE *initrd_path_f = NULL;
long machine_initrd_size;
uint32_t crc = 0;
EifHeader eif_header;
bool seen_sections[EIF_SECTION_MAX] = {false};
/* kernel + ramdisks + cmdline sha384 hash */
GList *iov_PCR0 = NULL;
/* kernel + boot ramdisk + cmdline sha384 hash */
GList *iov_PCR1 = NULL;
/* application ramdisk(s) hash */
GList *iov_PCR2 = NULL;
uint8_t *ptr = NULL;
struct iovec *iov_ptr = NULL;
*signature_found = false;
*kernel_path = *initrd_path = *cmdline = NULL;
f = fopen(eif_path, "rb");
if (f == NULL) {
error_setg_errno(errp, errno, "Failed to open %s", eif_path);
goto cleanup;
}
if (!read_eif_header(f, &eif_header, &crc, errp)) {
goto cleanup;
}
if (eif_header.version < 4) {
error_setg(errp, "Expected EIF version 4 or greater");
goto cleanup;
}
if (eif_header.flags != 0) {
error_setg(errp, "Expected EIF flags to be 0");
goto cleanup;
}
if (eif_header.section_cnt > MAX_SECTIONS) {
error_setg(errp, "EIF header section count must not be greater than "
"%d but found %d", MAX_SECTIONS, eif_header.section_cnt);
goto cleanup;
}
for (int i = 0; i < eif_header.section_cnt; ++i) {
EifSectionHeader hdr;
uint16_t section_type;
if (eif_header.section_offsets[i] > OFF_MAX) {
error_setg(errp, "Invalid EIF image. Section offset out of bounds");
goto cleanup;
}
if (fseek(f, eif_header.section_offsets[i], SEEK_SET) != 0) {
error_setg_errno(errp, errno, "Failed to offset to %" PRIu64 " in EIF file",
eif_header.section_offsets[i]);
goto cleanup;
}
if (!read_eif_section_header(f, &hdr, &crc, errp)) {
goto cleanup;
}
if (hdr.flags != 0) {
error_setg(errp, "Expected EIF section header flags to be 0");
goto cleanup;
}
if (eif_header.section_sizes[i] != hdr.section_size) {
error_setg(errp, "EIF section size mismatch between header and "
"section header: header %" PRIu64 ", section header %" PRIu64,
eif_header.section_sizes[i],
hdr.section_size);
goto cleanup;
}
section_type = hdr.section_type;
switch (section_type) {
case EIF_SECTION_KERNEL:
if (seen_sections[EIF_SECTION_KERNEL]) {
error_setg(errp, "Invalid EIF image. More than 1 kernel "
"section");
goto cleanup;
}
ptr = g_try_malloc(hdr.section_size);
if (!ptr) {
error_setg(errp, "Out of memory reading kernel section");
goto cleanup;
}
iov_ptr = g_malloc(sizeof(struct iovec));
iov_ptr->iov_base = ptr;
iov_ptr->iov_len = hdr.section_size;
iov_PCR0 = g_list_append(iov_PCR0, iov_ptr);
iov_PCR1 = g_list_append(iov_PCR1, iov_ptr);
if (!read_eif_kernel(f, hdr.section_size, kernel_path, ptr, &crc,
errp)) {
goto cleanup;
}
break;
case EIF_SECTION_CMDLINE:
{
uint64_t size;
uint8_t *cmdline_copy;
if (seen_sections[EIF_SECTION_CMDLINE]) {
error_setg(errp, "Invalid EIF image. More than 1 cmdline "
"section");
goto cleanup;
}
size = hdr.section_size;
*cmdline = g_try_malloc(size + 1);
if (!*cmdline) {
error_setg(errp, "Out of memory reading command line section");
goto cleanup;
}
if (!read_eif_cmdline(f, size, *cmdline, &crc, errp)) {
goto cleanup;
}
(*cmdline)[size] = '\0';
/*
* We make a copy of '*cmdline' for putting it in iovecs so that
* we can easily free all the iovec entries later as we cannot
* free '*cmdline' which is used by the caller.
*/
cmdline_copy = g_memdup2(*cmdline, size);
iov_ptr = g_malloc(sizeof(struct iovec));
iov_ptr->iov_base = cmdline_copy;
iov_ptr->iov_len = size;
iov_PCR0 = g_list_append(iov_PCR0, iov_ptr);
iov_PCR1 = g_list_append(iov_PCR1, iov_ptr);
break;
}
case EIF_SECTION_RAMDISK:
{
if (!seen_sections[EIF_SECTION_RAMDISK]) {
/*
* If this is the first time we are seeing a ramdisk section,
* we need to create the initrd temporary file.
*/
if (!get_tmp_file("eif-initrd-XXXXXX", initrd_path, errp)) {
goto cleanup;
}
initrd_path_f = fopen(*initrd_path, "wb");
if (initrd_path_f == NULL) {
error_setg_errno(errp, errno, "Failed to open file %s",
*initrd_path);
goto cleanup;
}
}
ptr = g_try_malloc(hdr.section_size);
if (!ptr) {
error_setg(errp, "Out of memory reading initrd section");
goto cleanup;
}
iov_ptr = g_malloc(sizeof(struct iovec));
iov_ptr->iov_base = ptr;
iov_ptr->iov_len = hdr.section_size;
iov_PCR0 = g_list_append(iov_PCR0, iov_ptr);
/*
* If it's the first ramdisk, we need to hash it into bootstrap
* i.e., iov_PCR1, otherwise we need to hash it into app i.e.,
* iov_PCR2.
*/
if (!seen_sections[EIF_SECTION_RAMDISK]) {
iov_PCR1 = g_list_append(iov_PCR1, iov_ptr);
} else {
iov_PCR2 = g_list_append(iov_PCR2, iov_ptr);
}
if (!read_eif_ramdisk(f, initrd_path_f, hdr.section_size, ptr,
&crc, errp)) {
goto cleanup;
}
break;
}
case EIF_SECTION_SIGNATURE:
*signature_found = true;
if (!get_signature_fingerprint_sha384(f, hdr.section_size,
fingerprint_sha384, &crc,
errp)) {
goto cleanup;
}
break;
default:
/* other sections including invalid or unknown sections */
{
uint8_t *buf;
size_t got;
uint64_t size = hdr.section_size;
buf = g_try_malloc(size);
if (!buf) {
error_setg(errp, "Out of memory reading unknown section");
goto cleanup;
}
got = fread(buf, 1, size, f);
if ((uint64_t) got != size) {
g_free(buf);
error_setg(errp, "Failed to read EIF %s section data",
section_type_to_string(section_type));
goto cleanup;
}
crc = crc32(crc, buf, size);
g_free(buf);
break;
}
}
if (section_type < EIF_SECTION_MAX) {
seen_sections[section_type] = true;
}
}
if (!seen_sections[EIF_SECTION_KERNEL]) {
error_setg(errp, "Invalid EIF image. No kernel section.");
goto cleanup;
}
if (!seen_sections[EIF_SECTION_CMDLINE]) {
error_setg(errp, "Invalid EIF image. No cmdline section.");
goto cleanup;
}
if (!seen_sections[EIF_SECTION_RAMDISK]) {
error_setg(errp, "Invalid EIF image. No ramdisk section.");
goto cleanup;
}
if (eif_header.eif_crc32 != crc) {
error_setg(errp, "CRC mismatch. Expected %u but header has %u.",
crc, eif_header.eif_crc32);
goto cleanup;
}
/*
* Let's append the initrd file from "-initrd" option if any. Although
* we pass the crc pointer to read_eif_ramdisk, it is not useful anymore.
* We have already done the crc mismatch check above this code.
*/
if (machine_initrd) {
machine_initrd_f = fopen(machine_initrd, "rb");
if (machine_initrd_f == NULL) {
error_setg_errno(errp, errno, "Failed to open initrd file %s",
machine_initrd);
goto cleanup;
}
machine_initrd_size = get_file_size(machine_initrd_f, errp);
if (machine_initrd_size == -1) {
goto cleanup;
}
ptr = g_try_malloc(machine_initrd_size);
if (!ptr) {
error_setg(errp, "Out of memory reading initrd file");
goto cleanup;
}
iov_ptr = g_malloc(sizeof(struct iovec));
iov_ptr->iov_base = ptr;
iov_ptr->iov_len = machine_initrd_size;
iov_PCR0 = g_list_append(iov_PCR0, iov_ptr);
iov_PCR2 = g_list_append(iov_PCR2, iov_ptr);
if (!read_eif_ramdisk(machine_initrd_f, initrd_path_f,
machine_initrd_size, ptr, &crc, errp)) {
goto cleanup;
}
}
if (!get_SHA384_digest(iov_PCR0, image_sha384, errp)) {
goto cleanup;
}
if (!get_SHA384_digest(iov_PCR1, bootstrap_sha384, errp)) {
goto cleanup;
}
if (!get_SHA384_digest(iov_PCR2, app_sha384, errp)) {
goto cleanup;
}
/*
* We only need to free iov_PCR0 entries because iov_PCR1 and
* iov_PCR2 iovec entries are subsets of iov_PCR0 iovec entries.
*/
g_list_free_full(iov_PCR0, (GDestroyNotify) free_iovec);
g_list_free(iov_PCR1);
g_list_free(iov_PCR2);
fclose(f);
fclose(initrd_path_f);
safe_fclose(machine_initrd_f);
return true;
cleanup:
g_list_free_full(iov_PCR0, (GDestroyNotify) free_iovec);
g_list_free(iov_PCR1);
g_list_free(iov_PCR2);
safe_fclose(f);
safe_fclose(initrd_path_f);
safe_fclose(machine_initrd_f);
safe_unlink(*kernel_path);
g_free(*kernel_path);
*kernel_path = NULL;
safe_unlink(*initrd_path);
g_free(*initrd_path);
*initrd_path = NULL;
g_free(*cmdline);
*cmdline = NULL;
return false;
}
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