[Qemu-devel] [PATCH v4 1/2] tpm: extend TPM emulator with state migration support

[Stefan Berger <stefanb@linux.vnet.ibm.com>]

Extend the TPM emulator backend device with state migration support.

The external TPM emulator 'swtpm' provides a protocol over
its control channel to retrieve its state blobs. We implement
functions for getting and setting the different state blobs.
In case the setting of the state blobs fails, we return a
negative errno code to fail the start of the VM.

Since we have an external TPM emulator, we need to make sure
that we do not migrate the state for as long as it is busy
processing a request. We need to wait for notification that
the request has completed processing.

Signed-off-by: Stefan Berger <stefanb@linux.vnet.ibm.com>
---
 hw/tpm/tpm_emulator.c | 312 ++++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 302 insertions(+), 10 deletions(-)

diff --git a/hw/tpm/tpm_emulator.c b/hw/tpm/tpm_emulator.c
index b787aee..da877e5 100644
--- a/hw/tpm/tpm_emulator.c
+++ b/hw/tpm/tpm_emulator.c
@@ -55,6 +55,19 @@
 #define TPM_EMULATOR_IMPLEMENTS_ALL_CAPS(S, cap) (((S)->caps & (cap)) == (cap))
 
 /* data structures */
+
+/* blobs from the TPM; part of VM state when migrating */
+typedef struct TPMBlobBuffers {
+    uint32_t permanent_flags;
+    TPMSizedBuffer permanent;
+
+    uint32_t volatil_flags;
+    TPMSizedBuffer volatil;
+
+    uint32_t savestate_flags;
+    TPMSizedBuffer savestate;
+} TPMBlobBuffers;
+
 typedef struct TPMEmulator {
     TPMBackend parent;
 
@@ -70,6 +83,8 @@ typedef struct TPMEmulator {
 
     unsigned int established_flag:1;
     unsigned int established_flag_cached:1;
+
+    TPMBlobBuffers state_blobs;
 } TPMEmulator;
 
 
@@ -301,7 +316,8 @@ static int tpm_emulator_set_buffer_size(TPMBackend *tb,
     return 0;
 }
 
-static int tpm_emulator_startup_tpm(TPMBackend *tb, size_t buffersize)
+static int _tpm_emulator_startup_tpm(TPMBackend *tb, size_t buffersize,
+                                     bool is_resume)
 {
     TPMEmulator *tpm_emu = TPM_EMULATOR(tb);
     ptm_init init = {
@@ -309,12 +325,17 @@ static int tpm_emulator_startup_tpm(TPMBackend *tb, size_t buffersize)
     };
     ptm_res res;
 
+    DPRINTF("%s   is_resume: %d", __func__, is_resume);
+
     if (buffersize != 0 &&
         tpm_emulator_set_buffer_size(tb, buffersize, NULL) < 0) {
         goto err_exit;
     }
 
-    DPRINTF("%s", __func__);
+    if (is_resume) {
+        init.u.req.init_flags = cpu_to_be32(PTM_INIT_FLAG_DELETE_VOLATILE);
+    }
+
     if (tpm_emulator_ctrlcmd(tpm_emu, CMD_INIT, &init, sizeof(init),
                              sizeof(init)) < 0) {
         error_report("tpm-emulator: could not send INIT: %s",
@@ -333,6 +354,11 @@ err_exit:
     return -1;
 }
 
+static int tpm_emulator_startup_tpm(TPMBackend *tb, size_t buffersize)
+{
+    return _tpm_emulator_startup_tpm(tb, buffersize, false);
+}
+
 static bool tpm_emulator_get_tpm_established_flag(TPMBackend *tb)
 {
     TPMEmulator *tpm_emu = TPM_EMULATOR(tb);
@@ -431,16 +457,21 @@ static size_t tpm_emulator_get_buffer_size(TPMBackend *tb)
 static int tpm_emulator_block_migration(TPMEmulator *tpm_emu)
 {
     Error *err = NULL;
+    ptm_cap caps = PTM_CAP_GET_STATEBLOB | PTM_CAP_SET_STATEBLOB |
+                   PTM_CAP_STOP;
 
-    error_setg(&tpm_emu->migration_blocker,
-               "Migration disabled: TPM emulator not yet migratable");
-    migrate_add_blocker(tpm_emu->migration_blocker, &err);
-    if (err) {
-        error_report_err(err);
-        error_free(tpm_emu->migration_blocker);
-        tpm_emu->migration_blocker = NULL;
+    if (!TPM_EMULATOR_IMPLEMENTS_ALL_CAPS(tpm_emu, caps)) {
+        error_setg(&tpm_emu->migration_blocker,
+                   "Migration disabled: TPM emulator does not support "
+                   "migration");
+        migrate_add_blocker(tpm_emu->migration_blocker, &err);
+        if (err) {
+            error_report_err(err);
+            error_free(tpm_emu->migration_blocker);
+            tpm_emu->migration_blocker = NULL;
 
-        return -1;
+            return -1;
+        }
     }
 
     return 0;
@@ -569,6 +600,263 @@ static const QemuOptDesc tpm_emulator_cmdline_opts[] = {
     { /* end of list */ },
 };
 
+/*
+ * Transfer a TPM state blob from the TPM into a provided buffer.
+ *
+ * @tpm_emu: TPMEmulator
+ * @type: the type of blob to transfer
+ * @tsb: the TPMSizeBuffer to fill with the blob
+ * @flags: the flags to return to the caller
+ */
+static int tpm_emulator_get_state_blob(TPMEmulator *tpm_emu,
+                                       uint8_t type,
+                                       TPMSizedBuffer *tsb,
+                                       uint32_t *flags)
+{
+    ptm_getstate pgs;
+    ptm_res res;
+    ssize_t n;
+    uint32_t totlength, length;
+
+    tpm_sized_buffer_reset(tsb);
+
+    pgs.u.req.state_flags = cpu_to_be32(PTM_STATE_FLAG_DECRYPTED);
+    pgs.u.req.type = cpu_to_be32(type);
+    pgs.u.req.offset = 0;
+
+    if (tpm_emulator_ctrlcmd(tpm_emu, CMD_GET_STATEBLOB,
+                             &pgs, sizeof(pgs.u.req),
+                             offsetof(ptm_getstate, u.resp.data)) < 0) {
+        error_report("tpm-emulator: could not get state blob type %d : %s",
+                     type, strerror(errno));
+        return -1;
+    }
+
+    res = be32_to_cpu(pgs.u.resp.tpm_result);
+    if (res != 0 && (res & 0x800) == 0) {
+        error_report("tpm-emulator: Getting the stateblob (type %d) failed "
+                     "with a TPM error 0x%x", type, res);
+        return -1;
+    }
+
+    totlength = be32_to_cpu(pgs.u.resp.totlength);
+    length = be32_to_cpu(pgs.u.resp.length);
+    if (totlength != length) {
+        error_report("tpm-emulator: Expecting to read %u bytes "
+                     "but would get %u", totlength, length);
+        return -1;
+    }
+
+    *flags = be32_to_cpu(pgs.u.resp.state_flags);
+
+    tsb->buffer = g_malloc(totlength);
+
+    n = qemu_chr_fe_read_all(&tpm_emu->ctrl_chr, tsb->buffer, totlength);
+    if (n != totlength) {
+        error_report("tpm-emulator: Could not read stateblob (type %d) : %s",
+                     type, strerror(errno));
+        return -1;
+    }
+    tsb->size = totlength;
+
+    DPRINTF("got state blob type %d, %d bytes, flags 0x%08x\n",
+            type, tsb->size, *flags);
+
+    return 0;
+}
+
+static int tpm_emulator_get_state_blobs(TPMEmulator *tpm_emu)
+{
+    TPMBlobBuffers *state_blobs = &tpm_emu->state_blobs;
+
+    if (tpm_emulator_get_state_blob(tpm_emu, PTM_BLOB_TYPE_PERMANENT,
+                                    &state_blobs->permanent,
+                                    &state_blobs->permanent_flags) < 0 ||
+        tpm_emulator_get_state_blob(tpm_emu, PTM_BLOB_TYPE_VOLATILE,
+                                    &state_blobs->volatil,
+                                    &state_blobs->volatil_flags) < 0 ||
+        tpm_emulator_get_state_blob(tpm_emu, PTM_BLOB_TYPE_SAVESTATE,
+                                    &state_blobs->savestate,
+                                    &state_blobs->savestate_flags) < 0) {
+        goto err_exit;
+    }
+
+    return 0;
+
+ err_exit:
+    tpm_sized_buffer_reset(&state_blobs->volatil);
+    tpm_sized_buffer_reset(&state_blobs->permanent);
+    tpm_sized_buffer_reset(&state_blobs->savestate);
+
+    return -1;
+}
+
+/*
+ * Transfer a TPM state blob to the TPM emulator.
+ *
+ * @tpm_emu: TPMEmulator
+ * @type: the type of TPM state blob to transfer
+ * @tsb: TPMSizeBuffer containing the TPM state blob
+ * @flags: Flags describing the (encryption) state of the TPM state blob
+ */
+static int tpm_emulator_set_state_blob(TPMEmulator *tpm_emu,
+                                       uint32_t type,
+                                       TPMSizedBuffer *tsb,
+                                       uint32_t flags)
+{
+    uint32_t offset = 0;
+    ssize_t n;
+    ptm_setstate pss;
+    ptm_res tpm_result;
+
+    if (tsb->size == 0) {
+        return 0;
+    }
+
+    pss = (ptm_setstate) {
+        .u.req.state_flags = cpu_to_be32(flags),
+        .u.req.type = cpu_to_be32(type),
+        .u.req.length = cpu_to_be32(tsb->size),
+    };
+
+    /* write the header only */
+    if (tpm_emulator_ctrlcmd(tpm_emu, CMD_SET_STATEBLOB, &pss,
+                             offsetof(ptm_setstate, u.req.data), 0) < 0) {
+        error_report("tpm-emulator: could not set state blob type %d : %s",
+                     type, strerror(errno));
+        return -1;
+    }
+
+    /* now the body */
+    n = qemu_chr_fe_write_all(&tpm_emu->ctrl_chr,
+                              &tsb->buffer[offset], tsb->size);
+    if (n != tsb->size) {
+        error_report("tpm-emulator: Writing the stateblob (type %d) "
+                     "failed: %s", type, strerror(errno));
+        return -1;
+    }
+
+    /* now get the result */
+    n = qemu_chr_fe_read_all(&tpm_emu->ctrl_chr,
+                             (uint8_t *)&pss, sizeof(pss.u.resp));
+    if (n != sizeof(pss.u.resp)) {
+        error_report("tpm-emulator: Reading response from writing stateblob "
+                     "(type %d) failed: %s", type, strerror(errno));
+        return -1;
+    }
+
+    tpm_result = be32_to_cpu(pss.u.resp.tpm_result);
+    if (tpm_result != 0) {
+        error_report("tpm-emulator: Setting the stateblob (type %d) failed "
+                     "with a TPM error 0x%x", type, tpm_result);
+        return -1;
+    }
+
+    DPRINTF("set the state blob type %d, %d bytes, flags 0x%08x\n",
+            type, tsb->size, flags);
+
+    return 0;
+}
+
+/*
+ * Set all the TPM state blobs.
+ *
+ * Returns a negative errno code in case of error.
+ */
+static int tpm_emulator_set_state_blobs(TPMBackend *tb)
+{
+    TPMEmulator *tpm_emu = TPM_EMULATOR(tb);
+    TPMBlobBuffers *state_blobs = &tpm_emu->state_blobs;
+
+    DPRINTF("%s: %d", __func__, __LINE__);
+
+    if (tpm_emulator_stop_tpm(tb) < 0) {
+        return -EIO;
+    }
+
+    if (tpm_emulator_set_state_blob(tpm_emu, PTM_BLOB_TYPE_PERMANENT,
+                                    &state_blobs->permanent,
+                                    state_blobs->permanent_flags) < 0 ||
+        tpm_emulator_set_state_blob(tpm_emu, PTM_BLOB_TYPE_VOLATILE,
+                                    &state_blobs->volatil,
+                                    state_blobs->volatil_flags) < 0 ||
+        tpm_emulator_set_state_blob(tpm_emu, PTM_BLOB_TYPE_SAVESTATE,
+                                    &state_blobs->savestate,
+                                    state_blobs->savestate_flags) < 0) {
+        return -EBADMSG;
+    }
+
+    DPRINTF("DONE SETTING STATEBLOBS");
+
+    return 0;
+}
+
+static int tpm_emulator_pre_save(void *opaque)
+{
+    TPMBackend *tb = opaque;
+    TPMEmulator *tpm_emu = TPM_EMULATOR(tb);
+
+    DPRINTF("%s", __func__);
+
+    tpm_backend_finish_sync(tb);
+
+    /* get the state blobs from the TPM */
+    return tpm_emulator_get_state_blobs(tpm_emu);
+}
+
+/*
+ * Load the TPM state blobs into the TPM.
+ *
+ * Returns negative errno codes in case of error.
+ */
+static int tpm_emulator_post_load(void *opaque,
+                                  int version_id __attribute__((unused)))
+{
+    TPMBackend *tb = opaque;
+    int ret;
+
+    ret = tpm_emulator_set_state_blobs(tb);
+    if (ret < 0) {
+        return ret;
+    }
+
+    if (_tpm_emulator_startup_tpm(tb, 0, true) < 0) {
+        return -EIO;
+    }
+
+    return 0;
+}
+
+static const VMStateDescription vmstate_tpm_emulator = {
+    .name = "tpm-emulator",
+    .version_id = 1,
+    .minimum_version_id = 0,
+    .minimum_version_id_old = 0,
+    .pre_save = tpm_emulator_pre_save,
+    .post_load = tpm_emulator_post_load,
+    .fields = (VMStateField[]) {
+        VMSTATE_UINT32(state_blobs.permanent_flags, TPMEmulator),
+        VMSTATE_UINT32(state_blobs.permanent.size, TPMEmulator),
+        VMSTATE_VBUFFER_ALLOC_UINT32(state_blobs.permanent.buffer,
+                                     TPMEmulator, 1, 0,
+                                     state_blobs.permanent.size),
+
+        VMSTATE_UINT32(state_blobs.volatil_flags, TPMEmulator),
+        VMSTATE_UINT32(state_blobs.volatil.size, TPMEmulator),
+        VMSTATE_VBUFFER_ALLOC_UINT32(state_blobs.volatil.buffer,
+                                     TPMEmulator, 1, 0,
+                                     state_blobs.volatil.size),
+
+        VMSTATE_UINT32(state_blobs.savestate_flags, TPMEmulator),
+        VMSTATE_UINT32(state_blobs.savestate.size, TPMEmulator),
+        VMSTATE_VBUFFER_ALLOC_UINT32(state_blobs.savestate.buffer,
+                                     TPMEmulator, 1, 0,
+                                     state_blobs.savestate.size),
+
+        VMSTATE_END_OF_LIST()
+    }
+};
+
 static void tpm_emulator_inst_init(Object *obj)
 {
     TPMEmulator *tpm_emu = TPM_EMULATOR(obj);
@@ -577,6 +865,8 @@ static void tpm_emulator_inst_init(Object *obj)
     tpm_emu->options = g_new0(TPMEmulatorOptions, 1);
     tpm_emu->cur_locty_number = ~0;
     qemu_mutex_init(&tpm_emu->mutex);
+
+    vmstate_register(NULL, -1, &vmstate_tpm_emulator, obj);
 }
 
 /*
@@ -613,6 +903,8 @@ static void tpm_emulator_inst_finalize(Object *obj)
     }
 
     qemu_mutex_destroy(&tpm_emu->mutex);
+
+    vmstate_unregister(NULL, &vmstate_tpm_emulator, obj);
 }
 
 static void tpm_emulator_class_init(ObjectClass *klass, void *data)
-- 
2.5.5