diff options
Diffstat (limited to 'target/i386/sev.c')
| -rw-r--r-- | target/i386/sev.c | 137 |
1 files changed, 137 insertions, 0 deletions
diff --git a/target/i386/sev.c b/target/i386/sev.c index fa7210473a..bcd9260fa4 100644 --- a/target/i386/sev.c +++ b/target/i386/sev.c @@ -23,6 +23,7 @@ #include "qemu/base64.h" #include "qemu/module.h" #include "qemu/uuid.h" +#include "crypto/hash.h" #include "sysemu/kvm.h" #include "sev_i386.h" #include "sysemu/sysemu.h" @@ -83,6 +84,32 @@ typedef struct __attribute__((__packed__)) SevInfoBlock { uint32_t reset_addr; } SevInfoBlock; +#define SEV_HASH_TABLE_RV_GUID "7255371f-3a3b-4b04-927b-1da6efa8d454" +typedef struct QEMU_PACKED SevHashTableDescriptor { + /* SEV hash table area guest address */ + uint32_t base; + /* SEV hash table area size (in bytes) */ + uint32_t size; +} SevHashTableDescriptor; + +/* hard code sha256 digest size */ +#define HASH_SIZE 32 + +typedef struct QEMU_PACKED SevHashTableEntry { + QemuUUID guid; + uint16_t len; + uint8_t hash[HASH_SIZE]; +} SevHashTableEntry; + +typedef struct QEMU_PACKED SevHashTable { + QemuUUID guid; + uint16_t len; + SevHashTableEntry cmdline; + SevHashTableEntry initrd; + SevHashTableEntry kernel; + uint8_t padding[]; +} SevHashTable; + static SevGuestState *sev_guest; static Error *sev_mig_blocker; @@ -1071,6 +1098,116 @@ int sev_es_save_reset_vector(void *flash_ptr, uint64_t flash_size) return 0; } +static const QemuUUID sev_hash_table_header_guid = { + .data = UUID_LE(0x9438d606, 0x4f22, 0x4cc9, 0xb4, 0x79, 0xa7, 0x93, + 0xd4, 0x11, 0xfd, 0x21) +}; + +static const QemuUUID sev_kernel_entry_guid = { + .data = UUID_LE(0x4de79437, 0xabd2, 0x427f, 0xb8, 0x35, 0xd5, 0xb1, + 0x72, 0xd2, 0x04, 0x5b) +}; +static const QemuUUID sev_initrd_entry_guid = { + .data = UUID_LE(0x44baf731, 0x3a2f, 0x4bd7, 0x9a, 0xf1, 0x41, 0xe2, + 0x91, 0x69, 0x78, 0x1d) +}; +static const QemuUUID sev_cmdline_entry_guid = { + .data = UUID_LE(0x97d02dd8, 0xbd20, 0x4c94, 0xaa, 0x78, 0xe7, 0x71, + 0x4d, 0x36, 0xab, 0x2a) +}; + +/* + * Add the hashes of the linux kernel/initrd/cmdline to an encrypted guest page + * which is included in SEV's initial memory measurement. + */ +bool sev_add_kernel_loader_hashes(SevKernelLoaderContext *ctx, Error **errp) +{ + uint8_t *data; + SevHashTableDescriptor *area; + SevHashTable *ht; + uint8_t cmdline_hash[HASH_SIZE]; + uint8_t initrd_hash[HASH_SIZE]; + uint8_t kernel_hash[HASH_SIZE]; + uint8_t *hashp; + size_t hash_len = HASH_SIZE; + int aligned_len; + + if (!pc_system_ovmf_table_find(SEV_HASH_TABLE_RV_GUID, &data, NULL)) { + error_setg(errp, "SEV: kernel specified but OVMF has no hash table guid"); + return false; + } + area = (SevHashTableDescriptor *)data; + + /* + * Calculate hash of kernel command-line with the terminating null byte. If + * the user doesn't supply a command-line via -append, the 1-byte "\0" will + * be used. + */ + hashp = cmdline_hash; + if (qcrypto_hash_bytes(QCRYPTO_HASH_ALG_SHA256, ctx->cmdline_data, + ctx->cmdline_size, &hashp, &hash_len, errp) < 0) { + return false; + } + assert(hash_len == HASH_SIZE); + + /* + * Calculate hash of initrd. If the user doesn't supply an initrd via + * -initrd, an empty buffer will be used (ctx->initrd_size == 0). + */ + hashp = initrd_hash; + if (qcrypto_hash_bytes(QCRYPTO_HASH_ALG_SHA256, ctx->initrd_data, + ctx->initrd_size, &hashp, &hash_len, errp) < 0) { + return false; + } + assert(hash_len == HASH_SIZE); + + /* Calculate hash of the kernel */ + hashp = kernel_hash; + struct iovec iov[2] = { + { .iov_base = ctx->setup_data, .iov_len = ctx->setup_size }, + { .iov_base = ctx->kernel_data, .iov_len = ctx->kernel_size } + }; + if (qcrypto_hash_bytesv(QCRYPTO_HASH_ALG_SHA256, iov, ARRAY_SIZE(iov), + &hashp, &hash_len, errp) < 0) { + return false; + } + assert(hash_len == HASH_SIZE); + + /* + * Populate the hashes table in the guest's memory at the OVMF-designated + * area for the SEV hashes table + */ + ht = qemu_map_ram_ptr(NULL, area->base); + + ht->guid = sev_hash_table_header_guid; + ht->len = sizeof(*ht); + + ht->cmdline.guid = sev_cmdline_entry_guid; + ht->cmdline.len = sizeof(ht->cmdline); + memcpy(ht->cmdline.hash, cmdline_hash, sizeof(ht->cmdline.hash)); + + ht->initrd.guid = sev_initrd_entry_guid; + ht->initrd.len = sizeof(ht->initrd); + memcpy(ht->initrd.hash, initrd_hash, sizeof(ht->initrd.hash)); + + ht->kernel.guid = sev_kernel_entry_guid; + ht->kernel.len = sizeof(ht->kernel); + memcpy(ht->kernel.hash, kernel_hash, sizeof(ht->kernel.hash)); + + /* When calling sev_encrypt_flash, the length has to be 16 byte aligned */ + aligned_len = ROUND_UP(ht->len, 16); + if (aligned_len != ht->len) { + /* zero the excess data so the measurement can be reliably calculated */ + memset(ht->padding, 0, aligned_len - ht->len); + } + + if (sev_encrypt_flash((uint8_t *)ht, aligned_len, errp) < 0) { + return false; + } + + return true; +} + static void sev_register_types(void) { |