[Qemu-devel] [PATCH 1/2] nvram: Add TPM NVRAM implementation

[Corey Bryant]

Provides TPM NVRAM implementation that enables storing of TPM
NVRAM data in a persistent image file.  The block driver is
used to read/write the drive image.  This will enable, for
example, an ecrypted QCOW2 image to be used to store sensitive
keys.

This patch provides APIs that a TPM backend can use to read and
write data.

Signed-off-by: Corey Bryant <address@hidden>
---
 hw/tpm/Makefile.objs |    1 +
 hw/tpm/tpm_nvram.c   |  399 ++++++++++++++++++++++++++++++++++++++++++++++++++
 hw/tpm/tpm_nvram.h   |   25 +++
 3 files changed, 425 insertions(+), 0 deletions(-)
 create mode 100644 hw/tpm/tpm_nvram.c
 create mode 100644 hw/tpm/tpm_nvram.h

diff --git a/hw/tpm/Makefile.objs b/hw/tpm/Makefile.objs
index 99f5983..49faef4 100644
--- a/hw/tpm/Makefile.objs
+++ b/hw/tpm/Makefile.objs
@@ -1,2 +1,3 @@
 common-obj-$(CONFIG_TPM_TIS) += tpm_tis.o
+common-obj-$(CONFIG_TPM_TIS) += tpm_nvram.o
 common-obj-$(CONFIG_TPM_PASSTHROUGH) += tpm_passthrough.o
diff --git a/hw/tpm/tpm_nvram.c b/hw/tpm/tpm_nvram.c
new file mode 100644
index 0000000..95ff396
--- /dev/null
+++ b/hw/tpm/tpm_nvram.c
@@ -0,0 +1,399 @@
+/*
+ * TPM NVRAM - enables storage of persistent NVRAM data on an image file
+ *
+ * Copyright (C) 2013 IBM Corporation
+ *
+ * Authors:
+ *  Stefan Berger    <address@hidden>
+ *  Corey Bryant     <address@hidden>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ */
+
+#include "tpm_nvram.h"
+#include "block/block_int.h"
+#include "qemu/thread.h"
+#include "sysemu/sysemu.h"
+
+/* #define TPM_NVRAM_DEBUG */
+
+#ifdef TPM_NVRAM_DEBUG
+#define DPRINTF(fmt, ...) \
+    do { fprintf(stderr, fmt, ## __VA_ARGS__); } while (0)
+#else
+#define DPRINTF(fmt, ...) \
+    do { } while (0)
+#endif
+
+/* Round a value up to the next SIZE */
+#define ROUNDUP(VAL, SIZE) \
+    (((VAL)+(SIZE)-1) & ~((SIZE)-1))
+
+/* Get the number of sectors required to contain SIZE bytes */
+#define NUM_SECTORS(SIZE) \
+    (ROUNDUP(SIZE, BDRV_SECTOR_SIZE) / BDRV_SECTOR_SIZE)
+
+/* Read/write request data */
+typedef struct TPMNvramRWRequest {
+    BlockDriverState *bdrv;
+    bool is_write;
+    uint64_t sector_num;
+    int num_sectors;
+    uint8_t **blob_r;
+    uint8_t *blob_w;
+    uint32_t size;
+    QEMUIOVector *qiov;
+    bool done;
+    int rc;
+
+    QemuMutex completion_mutex;
+    QemuCond completion;
+
+    QSIMPLEQ_ENTRY(TPMNvramRWRequest) list;
+} TPMNvramRWRequest;
+
+/* Mutex protected queue of read/write requests */
+static QemuMutex tpm_nvram_rwrequests_mutex;
+static QSIMPLEQ_HEAD(, TPMNvramRWRequest) tpm_nvram_rwrequests =
+    QSIMPLEQ_HEAD_INITIALIZER(tpm_nvram_rwrequests);
+
+static QEMUBH *tpm_nvram_bh;
+
+/*
+ * Increase the drive size if it's too small to store the blob
+ */
+static int tpm_nvram_adjust_size(BlockDriverState *bdrv, uint64_t sector_num,
+                                 int num_sectors)
+{
+    int rc = 0;
+    int64_t drive_size, required_size;
+
+    drive_size = bdrv_getlength(bdrv);
+    if (drive_size < 0) {
+        DPRINTF("%s: Unable to determine TPM NVRAM drive size\n", __func__);
+        rc = drive_size;
+        goto err_exit;
+    }
+
+    required_size = (sector_num + num_sectors) * BDRV_SECTOR_SIZE;
+
+    if (drive_size < required_size) {
+        rc = bdrv_truncate(bdrv, required_size);
+        if (rc < 0) {
+            DPRINTF("%s: TPM NVRAM drive too small\n", __func__);
+        }
+    }
+
+err_exit:
+    return rc;
+}
+
+/*
+ * Coroutine that reads a blob from the drive asynchronously
+ */
+static void coroutine_fn tpm_nvram_co_read(void *opaque)
+{
+    TPMNvramRWRequest *rwr = opaque;
+
+    rwr->rc = bdrv_co_readv(rwr->bdrv,
+                            rwr->sector_num,
+                            rwr->num_sectors,
+                            rwr->qiov);
+    rwr->done = true;
+}
+
+/*
+ * Coroutine that writes a blob to the drive asynchronously
+ */
+static void coroutine_fn tpm_nvram_co_write(void *opaque)
+{
+    TPMNvramRWRequest *rwr = opaque;
+
+    rwr->rc = bdrv_co_writev(rwr->bdrv,
+                             rwr->sector_num,
+                             rwr->num_sectors,
+                             rwr->qiov);
+    rwr->done = true;
+}
+
+/*
+ * Prepare for and enter a coroutine to read a blob from the drive
+ */
+static void tpm_nvram_do_co_read(TPMNvramRWRequest *rwr)
+{
+    Coroutine *co;
+    size_t buf_len = rwr->num_sectors * BDRV_SECTOR_SIZE;
+    uint8_t *buf = g_malloc(buf_len);
+
+    memset(buf, 0x0, buf_len);
+
+    struct iovec iov = {
+        .iov_base = (void *)buf,
+        .iov_len = rwr->size,
+    };
+
+    qemu_iovec_init_external(rwr->qiov, &iov, 1);
+
+    co = qemu_coroutine_create(tpm_nvram_co_read);
+    qemu_coroutine_enter(co, rwr);
+
+    while (!rwr->done) {
+        qemu_aio_wait();
+    }
+
+    if (rwr->rc == 0) {
+        rwr->rc = rwr->num_sectors;
+        *rwr->blob_r = g_malloc(rwr->size);
+        memcpy(*rwr->blob_r, buf, rwr->size);
+    } else {
+        *rwr->blob_r = NULL;
+    }
+
+    g_free(buf);
+}
+
+/*
+ * Prepare for and enter a coroutine to write a blob to the drive
+ */
+static void tpm_nvram_do_co_write(TPMNvramRWRequest *rwr)
+{
+    Coroutine *co;
+    size_t buf_len = rwr->num_sectors * BDRV_SECTOR_SIZE;
+    uint8_t *buf = g_malloc(buf_len);
+
+    memset(buf, 0x0, buf_len);
+    memcpy(buf, rwr->blob_w, rwr->size);
+
+    struct iovec iov = {
+        .iov_base = (void *)buf,
+        .iov_len = rwr->size,
+    };
+
+    qemu_iovec_init_external(rwr->qiov, &iov, 1);
+
+    rwr->rc = tpm_nvram_adjust_size(rwr->bdrv, rwr->sector_num,
+                                    rwr->num_sectors);
+    if (rwr->rc < 0) {
+        goto err_exit;
+    }
+
+    co = qemu_coroutine_create(tpm_nvram_co_write);
+    qemu_coroutine_enter(co, rwr);
+
+    while (!rwr->done) {
+        qemu_aio_wait();
+    }
+
+    if (rwr->rc == 0) {
+        rwr->rc = rwr->num_sectors;
+    }
+
+err_exit:
+    g_free(buf);
+}
+
+/*
+ * Initialization for read requests
+ */
+static TPMNvramRWRequest *tpm_nvram_rwrequest_init_read(BlockDriverState *bdrv,
+                                                        int64_t sector_num,
+                                                        uint8_t **blob,
+                                                        uint32_t size)
+{
+    TPMNvramRWRequest *rwr;
+
+    rwr = g_new0(TPMNvramRWRequest, 1);
+    rwr->bdrv = bdrv;
+    rwr->is_write = false;
+    rwr->sector_num = sector_num;
+    rwr->num_sectors = NUM_SECTORS(size);
+    rwr->blob_r = blob;
+    rwr->size = size;
+    rwr->qiov = g_new0(QEMUIOVector, 1);
+    rwr->done = false;
+
+    return rwr;
+}
+
+/*
+ * Initialization for write requests
+ */
+static TPMNvramRWRequest *tpm_nvram_rwrequest_init_write(BlockDriverState 
*bdrv,
+                                                         int64_t sector_num,
+                                                         uint8_t *blob,
+                                                         uint32_t size)
+{
+    TPMNvramRWRequest *rwr;
+
+    rwr = g_new0(TPMNvramRWRequest, 1);
+    rwr->bdrv = bdrv;
+    rwr->is_write = true;
+    rwr->sector_num = sector_num;
+    rwr->num_sectors = NUM_SECTORS(size);
+    rwr->blob_w = blob;
+    rwr->size = size;
+    rwr->qiov = g_new0(QEMUIOVector, 1);
+    rwr->done = false;
+
+    return rwr;
+}
+
+/*
+ * Free read/write request memory
+ */
+static void tpm_nvram_rwrequest_free(TPMNvramRWRequest *rwr)
+{
+    g_free(rwr->qiov);
+    g_free(rwr);
+}
+
+/*
+ * Execute a read or write of TPM NVRAM blob data
+ */
+static void tpm_nvram_rwrequest_exec(TPMNvramRWRequest *rwr)
+{
+    if (rwr->is_write) {
+        tpm_nvram_do_co_write(rwr);
+    } else {
+        tpm_nvram_do_co_read(rwr);
+    }
+
+    qemu_mutex_lock(&rwr->completion_mutex);
+    qemu_cond_signal(&rwr->completion);
+    qemu_mutex_unlock(&rwr->completion_mutex);
+}
+
+/*
+ * Bottom-half callback that is invoked by QEMU's main thread to
+ * process TPM NVRAM read/write requests.
+ */
+static void tpm_nvram_rwrequest_callback(void *opaque)
+{
+    TPMNvramRWRequest *rwr, *next;
+
+    qemu_mutex_lock(&tpm_nvram_rwrequests_mutex);
+
+    QSIMPLEQ_FOREACH_SAFE(rwr, &tpm_nvram_rwrequests, list, next) {
+        QSIMPLEQ_REMOVE(&tpm_nvram_rwrequests, rwr, TPMNvramRWRequest, list);
+
+        qemu_mutex_unlock(&tpm_nvram_rwrequests_mutex);
+        tpm_nvram_rwrequest_exec(rwr);
+        qemu_mutex_lock(&tpm_nvram_rwrequests_mutex);
+    }
+
+    qemu_mutex_unlock(&tpm_nvram_rwrequests_mutex);
+}
+
+/*
+ * Schedule a bottom-half to read or write a blob to the TPM NVRAM drive
+ */
+static void tpm_nvram_rwrequest_schedule(TPMNvramRWRequest *rwr)
+{
+    qemu_mutex_lock(&tpm_nvram_rwrequests_mutex);
+    QSIMPLEQ_INSERT_TAIL(&tpm_nvram_rwrequests, rwr, list);
+    qemu_mutex_unlock(&tpm_nvram_rwrequests_mutex);
+
+    qemu_bh_schedule(tpm_nvram_bh);
+
+    /* Wait for completion of the read/write request */
+    qemu_mutex_lock(&rwr->completion_mutex);
+    qemu_cond_wait(&rwr->completion, &rwr->completion_mutex);
+    qemu_mutex_unlock(&rwr->completion_mutex);
+}
+
+/*
+ * Initialize a TPM NVRAM drive
+ */
+int tpm_nvram_init(BlockDriverState *bdrv)
+{
+    qemu_mutex_init(&tpm_nvram_rwrequests_mutex);
+    tpm_nvram_bh = qemu_bh_new(tpm_nvram_rwrequest_callback, NULL);
+
+    if (bdrv_is_read_only(bdrv)) {
+        DPRINTF("%s: TPM NVRAM drive '%s' is read-only\n", __func__,
+                bdrv->filename);
+        return -EPERM;
+    }
+
+    bdrv_lock_medium(bdrv, true);
+
+    DPRINTF("%s: TPM NVRAM drive '%s' initialized successfully\n", __func__,
+            bdrv->filename);
+
+    return 0;
+}
+
+/*
+ * Read a TPM NVRAM blob from the drive.  On success, returns the
+ * number of sectors used by this blob.
+ */
+int tpm_nvram_read(BlockDriverState *bdrv, int64_t sector_num,
+                   uint8_t **blob, uint32_t size)
+{
+    int rc;
+    TPMNvramRWRequest *rwr;
+
+    *blob = NULL;
+
+    if (!bdrv) {
+        return -EPERM;
+    }
+
+    if (sector_num < 0) {
+        return -EINVAL;
+    }
+
+    rwr = tpm_nvram_rwrequest_init_read(bdrv, sector_num, blob, size);
+    tpm_nvram_rwrequest_schedule(rwr);
+    rc = rwr->rc;
+
+#ifdef TPM_NVRAM_DEBUG
+    if (rc < 0) {
+        DPRINTF("%s: TPM NVRAM read failed\n", __func__);
+    } else {
+        DPRINTF("%s: TPM NVRAM read successful: sector_num=%"PRIu64", "
+                "size=%"PRIu32", num_sectors=%d\n", __func__,
+                rwr->sector_num, rwr->size, rwr->num_sectors);
+    }
+#endif
+
+    tpm_nvram_rwrequest_free(rwr);
+    return rc;
+}
+
+/*
+ * Write a TPM NVRAM blob to the drive.  On success, returns the
+ * number of sectors used by this blob.
+ */
+int tpm_nvram_write(BlockDriverState *bdrv, int64_t sector_num,
+                    uint8_t *blob, uint32_t size)
+{
+    int rc;
+    TPMNvramRWRequest *rwr;
+
+    if (!bdrv) {
+        return -EPERM;
+    }
+
+    if (sector_num < 0 || !blob) {
+        return -EINVAL;
+    }
+
+    rwr = tpm_nvram_rwrequest_init_write(bdrv, sector_num, blob, size);
+    tpm_nvram_rwrequest_schedule(rwr);
+    rc = rwr->rc;
+
+#ifdef TPM_NVRAM_DEBUG
+    if (rc < 0) {
+        DPRINTF("%s: TPM NVRAM write failed\n", __func__);
+    } else {
+        DPRINTF("%s: TPM NVRAM write successful: sector_num=%"PRIu64", "
+                "size=%"PRIu32", num_sectors=%d\n", __func__,
+                rwr->sector_num, rwr->size, rwr->num_sectors);
+    }
+#endif
+
+    tpm_nvram_rwrequest_free(rwr);
+    return rc;
+}
diff --git a/hw/tpm/tpm_nvram.h b/hw/tpm/tpm_nvram.h
new file mode 100644
index 0000000..fceb4d0
--- /dev/null
+++ b/hw/tpm/tpm_nvram.h
@@ -0,0 +1,25 @@
+/*
+ * TPM NVRAM - enables storage of persistent NVRAM data on an image file
+ *
+ * Copyright (C) 2013 IBM Corporation
+ *
+ * Authors:
+ *  Stefan Berger    <address@hidden>
+ *  Corey Bryant     <address@hidden>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ */
+
+#ifndef TPM_TPM_NVRAM_H
+#define TPM_TPM_NVRAM_H
+
+#include "block/block.h"
+
+int tpm_nvram_init(BlockDriverState *bdrv);
+int tpm_nvram_read(BlockDriverState *bdrv, int64_t sector_num,
+                   uint8_t **blob, uint32_t size);
+int tpm_nvram_write(BlockDriverState *bdrv, int64_t sector_num,
+                    uint8_t *blob, uint32_t size);
+
+#endif
-- 
1.7.1