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[mirror_qemu.git] / block / crypto.c
index 24823835c1c228d8b1f0456681c80551587ba9b3..aef5a5721a929eec2b3614fab73e6549497d4b93 100644 (file)
@@ -6,7 +6,7 @@
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
  * License as published by the Free Software Foundation; either
- * version 2 of the License, or (at your option) any later version.
+ * version 2.1 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
 #include "qapi/error.h"
 #include "qemu/module.h"
 #include "qemu/option.h"
+#include "qemu/cutils.h"
 #include "crypto.h"
 
 typedef struct BlockCrypto BlockCrypto;
 
 struct BlockCrypto {
     QCryptoBlock *block;
+    bool updating_keys;
 };
 
 
@@ -70,6 +72,24 @@ static ssize_t block_crypto_read_func(QCryptoBlock *block,
     return ret;
 }
 
+static ssize_t block_crypto_write_func(QCryptoBlock *block,
+                                       size_t offset,
+                                       const uint8_t *buf,
+                                       size_t buflen,
+                                       void *opaque,
+                                       Error **errp)
+{
+    BlockDriverState *bs = opaque;
+    ssize_t ret;
+
+    ret = bdrv_pwrite(bs->file, offset, buf, buflen);
+    if (ret < 0) {
+        error_setg_errno(errp, -ret, "Could not write encryption header");
+        return ret;
+    }
+    return ret;
+}
+
 
 struct BlockCryptoCreateData {
     BlockBackend *blk;
@@ -78,12 +98,12 @@ struct BlockCryptoCreateData {
 };
 
 
-static ssize_t block_crypto_write_func(QCryptoBlock *block,
-                                       size_t offset,
-                                       const uint8_t *buf,
-                                       size_t buflen,
-                                       void *opaque,
-                                       Error **errp)
+static ssize_t block_crypto_create_write_func(QCryptoBlock *block,
+                                              size_t offset,
+                                              const uint8_t *buf,
+                                              size_t buflen,
+                                              void *opaque,
+                                              Error **errp)
 {
     struct BlockCryptoCreateData *data = opaque;
     ssize_t ret;
@@ -96,25 +116,41 @@ static ssize_t block_crypto_write_func(QCryptoBlock *block,
     return ret;
 }
 
-
-static ssize_t block_crypto_init_func(QCryptoBlock *block,
-                                      size_t headerlen,
-                                      void *opaque,
-                                      Error **errp)
+static ssize_t block_crypto_create_init_func(QCryptoBlock *block,
+                                             size_t headerlen,
+                                             void *opaque,
+                                             Error **errp)
 {
     struct BlockCryptoCreateData *data = opaque;
+    Error *local_error = NULL;
+    int ret;
 
     if (data->size > INT64_MAX || headerlen > INT64_MAX - data->size) {
-        error_setg(errp, "The requested file size is too large");
-        return -EFBIG;
+        ret = -EFBIG;
+        goto error;
     }
 
     /* User provided size should reflect amount of space made
      * available to the guest, so we must take account of that
      * which will be used by the crypto header
      */
-    return blk_truncate(data->blk, data->size + headerlen, false,
-                        data->prealloc, errp);
+    ret = blk_truncate(data->blk, data->size + headerlen, false,
+                       data->prealloc, 0, &local_error);
+
+    if (ret >= 0) {
+        return ret;
+    }
+
+error:
+    if (ret == -EFBIG) {
+        /* Replace the error message with a better one */
+        error_free(local_error);
+        error_setg(errp, "The requested file size is too large");
+    } else {
+        error_propagate(errp, local_error);
+    }
+
+    return ret;
 }
 
 
@@ -149,6 +185,19 @@ static QemuOptsList block_crypto_create_opts_luks = {
 };
 
 
+static QemuOptsList block_crypto_amend_opts_luks = {
+    .name = "crypto",
+    .head = QTAILQ_HEAD_INITIALIZER(block_crypto_create_opts_luks.head),
+    .desc = {
+        BLOCK_CRYPTO_OPT_DEF_LUKS_STATE(""),
+        BLOCK_CRYPTO_OPT_DEF_LUKS_KEYSLOT(""),
+        BLOCK_CRYPTO_OPT_DEF_LUKS_OLD_SECRET(""),
+        BLOCK_CRYPTO_OPT_DEF_LUKS_NEW_SECRET(""),
+        BLOCK_CRYPTO_OPT_DEF_LUKS_ITER_TIME(""),
+        { /* end of list */ }
+    },
+};
+
 QCryptoBlockOpenOptions *
 block_crypto_open_opts_init(QDict *opts, Error **errp)
 {
@@ -184,6 +233,23 @@ block_crypto_create_opts_init(QDict *opts, Error **errp)
     return ret;
 }
 
+QCryptoBlockAmendOptions *
+block_crypto_amend_opts_init(QDict *opts, Error **errp)
+{
+    Visitor *v;
+    QCryptoBlockAmendOptions *ret;
+
+    v = qobject_input_visitor_new_flat_confused(opts, errp);
+    if (!v) {
+        return NULL;
+    }
+
+    visit_type_QCryptoBlockAmendOptions(v, NULL, &ret, errp);
+
+    visit_free(v);
+    return ret;
+}
+
 
 static int block_crypto_open_generic(QCryptoBlockFormat format,
                                      QemuOptsList *opts_spec,
@@ -194,14 +260,13 @@ static int block_crypto_open_generic(QCryptoBlockFormat format,
 {
     BlockCrypto *crypto = bs->opaque;
     QemuOpts *opts = NULL;
-    Error *local_err = NULL;
     int ret = -EINVAL;
     QCryptoBlockOpenOptions *open_opts = NULL;
     unsigned int cflags = 0;
     QDict *cryptoopts = NULL;
 
-    bs->file = bdrv_open_child(NULL, options, "file", bs, &child_file,
-                               false, errp);
+    bs->file = bdrv_open_child(NULL, options, "file", bs, &child_of_bds,
+                               BDRV_CHILD_IMAGE, false, errp);
     if (!bs->file) {
         return -EINVAL;
     }
@@ -210,9 +275,7 @@ static int block_crypto_open_generic(QCryptoBlockFormat format,
         bs->file->bs->supported_write_flags;
 
     opts = qemu_opts_create(opts_spec, NULL, 0, &error_abort);
-    qemu_opts_absorb_qdict(opts, options, &local_err);
-    if (local_err) {
-        error_propagate(errp, local_err);
+    if (!qemu_opts_absorb_qdict(opts, options, errp)) {
         goto cleanup;
     }
 
@@ -260,11 +323,10 @@ static int block_crypto_co_create_generic(BlockDriverState *bs,
     QCryptoBlock *crypto = NULL;
     struct BlockCryptoCreateData data;
 
-    blk = blk_new(bdrv_get_aio_context(bs),
-                  BLK_PERM_WRITE | BLK_PERM_RESIZE, BLK_PERM_ALL);
-
-    ret = blk_insert_bs(blk, bs, errp);
-    if (ret < 0) {
+    blk = blk_new_with_bs(bs, BLK_PERM_WRITE | BLK_PERM_RESIZE, BLK_PERM_ALL,
+                          errp);
+    if (!blk) {
+        ret = -EPERM;
         goto cleanup;
     }
 
@@ -279,8 +341,8 @@ static int block_crypto_co_create_generic(BlockDriverState *bs,
     };
 
     crypto = qcrypto_block_create(opts, NULL,
-                                  block_crypto_init_func,
-                                  block_crypto_write_func,
+                                  block_crypto_create_init_func,
+                                  block_crypto_create_write_func,
                                   &data,
                                   errp);
 
@@ -298,7 +360,8 @@ static int block_crypto_co_create_generic(BlockDriverState *bs,
 
 static int coroutine_fn
 block_crypto_co_truncate(BlockDriverState *bs, int64_t offset, bool exact,
-                         PreallocMode prealloc, Error **errp)
+                         PreallocMode prealloc, BdrvRequestFlags flags,
+                         Error **errp)
 {
     BlockCrypto *crypto = bs->opaque;
     uint64_t payload_offset =
@@ -311,7 +374,7 @@ block_crypto_co_truncate(BlockDriverState *bs, int64_t offset, bool exact,
 
     offset += payload_offset;
 
-    return bdrv_co_truncate(bs->file, offset, exact, prealloc, errp);
+    return bdrv_co_truncate(bs->file, offset, exact, prealloc, 0, errp);
 }
 
 static void block_crypto_close(BlockDriverState *bs)
@@ -484,6 +547,67 @@ static int64_t block_crypto_getlength(BlockDriverState *bs)
 }
 
 
+static BlockMeasureInfo *block_crypto_measure(QemuOpts *opts,
+                                              BlockDriverState *in_bs,
+                                              Error **errp)
+{
+    g_autoptr(QCryptoBlockCreateOptions) create_opts = NULL;
+    Error *local_err = NULL;
+    BlockMeasureInfo *info;
+    uint64_t size;
+    size_t luks_payload_size;
+    QDict *cryptoopts;
+
+    /*
+     * Preallocation mode doesn't affect size requirements but we must consume
+     * the option.
+     */
+    g_free(qemu_opt_get_del(opts, BLOCK_OPT_PREALLOC));
+
+    size = qemu_opt_get_size_del(opts, BLOCK_OPT_SIZE, 0);
+
+    if (in_bs) {
+        int64_t ssize = bdrv_getlength(in_bs);
+
+        if (ssize < 0) {
+            error_setg_errno(&local_err, -ssize,
+                             "Unable to get image virtual_size");
+            goto err;
+        }
+
+        size = ssize;
+    }
+
+    cryptoopts = qemu_opts_to_qdict_filtered(opts, NULL,
+            &block_crypto_create_opts_luks, true);
+    qdict_put_str(cryptoopts, "format", "luks");
+    create_opts = block_crypto_create_opts_init(cryptoopts, &local_err);
+    qobject_unref(cryptoopts);
+    if (!create_opts) {
+        goto err;
+    }
+
+    if (!qcrypto_block_calculate_payload_offset(create_opts, NULL,
+                                                &luks_payload_size,
+                                                &local_err)) {
+        goto err;
+    }
+
+    /*
+     * Unallocated blocks are still encrypted so allocation status makes no
+     * difference to the file size.
+     */
+    info = g_new0(BlockMeasureInfo, 1);
+    info->fully_allocated = luks_payload_size + size;
+    info->required = luks_payload_size + size;
+    return info;
+
+err:
+    error_propagate(errp, local_err);
+    return NULL;
+}
+
+
 static int block_crypto_probe_luks(const uint8_t *buf,
                                    int buf_size,
                                    const char *filename) {
@@ -539,7 +663,8 @@ fail:
     return ret;
 }
 
-static int coroutine_fn block_crypto_co_create_opts_luks(const char *filename,
+static int coroutine_fn block_crypto_co_create_opts_luks(BlockDriver *drv,
+                                                         const char *filename,
                                                          QemuOpts *opts,
                                                          Error **errp)
 {
@@ -596,6 +721,23 @@ static int coroutine_fn block_crypto_co_create_opts_luks(const char *filename,
 
     ret = 0;
 fail:
+    /*
+     * If an error occurred, delete 'filename'. Even if the file existed
+     * beforehand, it has been truncated and corrupted in the process.
+     */
+    if (ret && bs) {
+        Error *local_delete_err = NULL;
+        int r_del = bdrv_co_delete_file(bs, &local_delete_err);
+        /*
+         * ENOTSUP will happen if the block driver doesn't support
+         * the 'bdrv_co_delete_file' interface. This is a predictable
+         * scenario and shouldn't be reported back to the user.
+         */
+        if ((r_del < 0) && (r_del != -ENOTSUP)) {
+            error_report_err(local_delete_err);
+        }
+    }
+
     bdrv_unref(bs);
     qapi_free_QCryptoBlockCreateOptions(create_opts);
     qobject_unref(cryptoopts);
@@ -613,7 +755,6 @@ static int block_crypto_get_info_luks(BlockDriverState *bs,
         return ret;
     }
 
-    bdi->unallocated_blocks_are_zero = false;
     bdi->cluster_size = subbdi.cluster_size;
 
     return 0;
@@ -645,6 +786,131 @@ block_crypto_get_specific_info_luks(BlockDriverState *bs, Error **errp)
     return spec_info;
 }
 
+static int
+block_crypto_amend_options_generic_luks(BlockDriverState *bs,
+                                        QCryptoBlockAmendOptions *amend_options,
+                                        bool force,
+                                        Error **errp)
+{
+    BlockCrypto *crypto = bs->opaque;
+    int ret;
+
+    assert(crypto);
+    assert(crypto->block);
+
+    /* apply for exclusive read/write permissions to the underlying file*/
+    crypto->updating_keys = true;
+    ret = bdrv_child_refresh_perms(bs, bs->file, errp);
+    if (ret) {
+        goto cleanup;
+    }
+
+    ret = qcrypto_block_amend_options(crypto->block,
+                                      block_crypto_read_func,
+                                      block_crypto_write_func,
+                                      bs,
+                                      amend_options,
+                                      force,
+                                      errp);
+cleanup:
+    /* release exclusive read/write permissions to the underlying file*/
+    crypto->updating_keys = false;
+    bdrv_child_refresh_perms(bs, bs->file, errp);
+    return ret;
+}
+
+static int
+block_crypto_amend_options_luks(BlockDriverState *bs,
+                                QemuOpts *opts,
+                                BlockDriverAmendStatusCB *status_cb,
+                                void *cb_opaque,
+                                bool force,
+                                Error **errp)
+{
+    BlockCrypto *crypto = bs->opaque;
+    QDict *cryptoopts = NULL;
+    QCryptoBlockAmendOptions *amend_options = NULL;
+    int ret = -EINVAL;
+
+    assert(crypto);
+    assert(crypto->block);
+
+    cryptoopts = qemu_opts_to_qdict(opts, NULL);
+    qdict_put_str(cryptoopts, "format", "luks");
+    amend_options = block_crypto_amend_opts_init(cryptoopts, errp);
+    qobject_unref(cryptoopts);
+    if (!amend_options) {
+        goto cleanup;
+    }
+    ret = block_crypto_amend_options_generic_luks(bs, amend_options,
+                                                  force, errp);
+cleanup:
+    qapi_free_QCryptoBlockAmendOptions(amend_options);
+    return ret;
+}
+
+static int
+coroutine_fn block_crypto_co_amend_luks(BlockDriverState *bs,
+                                        BlockdevAmendOptions *opts,
+                                        bool force,
+                                        Error **errp)
+{
+    QCryptoBlockAmendOptions amend_opts;
+
+    amend_opts = (QCryptoBlockAmendOptions) {
+        .format = Q_CRYPTO_BLOCK_FORMAT_LUKS,
+        .u.luks = *qapi_BlockdevAmendOptionsLUKS_base(&opts->u.luks),
+    };
+    return block_crypto_amend_options_generic_luks(bs, &amend_opts,
+                                                   force, errp);
+}
+
+static void
+block_crypto_child_perms(BlockDriverState *bs, BdrvChild *c,
+                         const BdrvChildRole role,
+                         BlockReopenQueue *reopen_queue,
+                         uint64_t perm, uint64_t shared,
+                         uint64_t *nperm, uint64_t *nshared)
+{
+
+    BlockCrypto *crypto = bs->opaque;
+
+    bdrv_default_perms(bs, c, role, reopen_queue, perm, shared, nperm, nshared);
+
+    /*
+     * For backward compatibility, manually share the write
+     * and resize permission
+     */
+    *nshared |= shared & (BLK_PERM_WRITE | BLK_PERM_RESIZE);
+    /*
+     * Since we are not fully a format driver, don't always request
+     * the read/resize permission but only when explicitly
+     * requested
+     */
+    *nperm &= ~(BLK_PERM_WRITE | BLK_PERM_RESIZE);
+    *nperm |= perm & (BLK_PERM_WRITE | BLK_PERM_RESIZE);
+
+    /*
+     * This driver doesn't modify LUKS metadata except
+     * when updating the encryption slots.
+     * Thus unlike a proper format driver we don't ask for
+     * shared write/read permission. However we need it
+     * when we are updating the keys, to ensure that only we
+     * have access to the device.
+     *
+     * Encryption update will set the crypto->updating_keys
+     * during that period and refresh permissions
+     *
+     */
+    if (crypto->updating_keys) {
+        /* need exclusive write access for header update */
+        *nperm |= BLK_PERM_WRITE;
+        /* unshare read and write permission */
+        *nshared &= ~(BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE);
+    }
+}
+
+
 static const char *const block_crypto_strong_runtime_opts[] = {
     BLOCK_CRYPTO_OPT_LUKS_KEY_SECRET,
 
@@ -657,21 +923,25 @@ static BlockDriver bdrv_crypto_luks = {
     .bdrv_probe         = block_crypto_probe_luks,
     .bdrv_open          = block_crypto_open_luks,
     .bdrv_close         = block_crypto_close,
-    /* This driver doesn't modify LUKS metadata except when creating image.
-     * Allow share-rw=on as a special case. */
-    .bdrv_child_perm    = bdrv_filter_default_perms,
+    .bdrv_child_perm    = block_crypto_child_perms,
     .bdrv_co_create     = block_crypto_co_create_luks,
     .bdrv_co_create_opts = block_crypto_co_create_opts_luks,
     .bdrv_co_truncate   = block_crypto_co_truncate,
     .create_opts        = &block_crypto_create_opts_luks,
+    .amend_opts         = &block_crypto_amend_opts_luks,
 
     .bdrv_reopen_prepare = block_crypto_reopen_prepare,
     .bdrv_refresh_limits = block_crypto_refresh_limits,
     .bdrv_co_preadv     = block_crypto_co_preadv,
     .bdrv_co_pwritev    = block_crypto_co_pwritev,
     .bdrv_getlength     = block_crypto_getlength,
+    .bdrv_measure       = block_crypto_measure,
     .bdrv_get_info      = block_crypto_get_info_luks,
     .bdrv_get_specific_info = block_crypto_get_specific_info_luks,
+    .bdrv_amend_options = block_crypto_amend_options_luks,
+    .bdrv_co_amend      = block_crypto_co_amend_luks,
+
+    .is_format          = true,
 
     .strong_runtime_opts = block_crypto_strong_runtime_opts,
 };