Re: [Qemu-block] [PATCH 03/10] qcrypto-luks: implement the encryption key management

[Daniel P . Berrangé]

On Fri, Aug 30, 2019 at 11:56:01PM +0300, Maxim Levitsky wrote:
> Signed-off-by: Maxim Levitsky <address@hidden>
> ---
>  crypto/block-luks.c | 366 +++++++++++++++++++++++++++++++++++++++++++-
>  1 file changed, 364 insertions(+), 2 deletions(-)
> 
> diff --git a/crypto/block-luks.c b/crypto/block-luks.c
> index ba20d55246..21325fbc79 100644
> --- a/crypto/block-luks.c
> +++ b/crypto/block-luks.c
> @@ -70,6 +70,9 @@ typedef struct QCryptoBlockLUKSKeySlot 
> QCryptoBlockLUKSKeySlot;
>  
>  #define QCRYPTO_BLOCK_LUKS_SECTOR_SIZE 512LL
>  
> +#define QCRYPTO_BLOCK_LUKS_DEFAULT_ITER_TIME 2000

Perhaps use  ITER_TIME_MS to make it clear it is millisecs

> +#define QCRYPTO_BLOCK_LUKS_ERASE_ITERATIONS 40
> +
>  static const char qcrypto_block_luks_magic[QCRYPTO_BLOCK_LUKS_MAGIC_LEN] = {
>      'L', 'U', 'K', 'S', 0xBA, 0xBE
>  };
> @@ -219,6 +222,9 @@ struct QCryptoBlockLUKS {
>  
>      /* Hash algorithm used in pbkdf2 function */
>      QCryptoHashAlgorithm hash_alg;
> +
> +    /* Name of the secret that was used to open the image */
> +    char *secret;

> +
> +/*
> + * Returns true if a slot i is marked as active
> + * (contains encrypted copy of the master key)
> + */
> +
> +static bool

No blank line is wanted between the comment & function.
Likewise for the rest of this patch series

> +qcrypto_block_luks_slot_active(const QCryptoBlockLUKS *luks,
> +                               unsigned int slot_idx)
> +{
> +    uint32_t val = luks->header.key_slots[slot_idx].active;
> +    return val ==  QCRYPTO_BLOCK_LUKS_KEY_SLOT_ENABLED;
> +}



> +static int
> +qcrypto_block_luks_erase_key(QCryptoBlock *block,
> +                             unsigned int slot_idx,
> +                             QCryptoBlockWriteFunc writefunc,
> +                             void *opaque,
> +                             Error **errp)
> +{
> +    QCryptoBlockLUKS *luks = block->opaque;
> +    QCryptoBlockLUKSKeySlot *slot = &luks->header.key_slots[slot_idx];
> +    g_autofree uint8_t *garbagesplitkey = NULL;
> +    size_t splitkeylen = luks->header.master_key_len * slot->stripes;
> +    size_t i;
> +
> +    assert(slot_idx < QCRYPTO_BLOCK_LUKS_NUM_KEY_SLOTS);
> +    assert(splitkeylen > 0);
> +
> +    garbagesplitkey = g_malloc0(splitkeylen);

I'd prefer   g_new0(uint8_t, splitkeylen)

> +
> +    /* Reset the key slot header */
> +    memset(slot->salt, 0, QCRYPTO_BLOCK_LUKS_SALT_LEN);
> +    slot->iterations = 0;
> +    slot->active = QCRYPTO_BLOCK_LUKS_KEY_SLOT_DISABLED;
> +


> @@ -1522,6 +1700,187 @@ qcrypto_block_luks_create(QCryptoBlock *block,
>  }
>  
>  
> +#define CHECK_NON_AMEND_OPTION(luks, luks_opts, name) \
> +    if (luks_opts.has_##name && luks_opts.name != luks->name) { \
> +            error_setg(errp, "Option \"" #name "\" can't be amended"); \
> +            goto cleanup; \
> +    }
> +
> +static int
> +qcrypto_block_luks_amend_options(QCryptoBlock *block,
> +                                 QCryptoBlockReadFunc readfunc,
> +                                 QCryptoBlockWriteFunc writefunc,
> +                                 void *opaque,
> +                                 QCryptoBlockCreateOptions *options,
> +                                 bool force,
> +                                 Error **errp)
> +{
> +    QCryptoBlockLUKS *luks = block->opaque;
> +    QCryptoBlockCreateOptionsLUKS luks_opts;
> +    g_autofree char *old_password = NULL;
> +    g_autofree char *password = NULL;
> +    const char *unlock_secret = luks->secret;
> +    g_autofree uint8_t *masterkey = NULL;
> +    int slot = -1;
> +    int ret = -1;
> +    bool active = true;
> +    int64_t iter_time = QCRYPTO_BLOCK_LUKS_DEFAULT_ITER_TIME;
> +
> +    memcpy(&luks_opts, &options->u.luks, sizeof(luks_opts));
> +
> +    CHECK_NON_AMEND_OPTION(luks, luks_opts, cipher_alg);
> +    CHECK_NON_AMEND_OPTION(luks, luks_opts, cipher_mode);
> +    CHECK_NON_AMEND_OPTION(luks, luks_opts, ivgen_alg);
> +    CHECK_NON_AMEND_OPTION(luks, luks_opts, ivgen_hash_alg);
> +    CHECK_NON_AMEND_OPTION(luks, luks_opts, hash_alg);
> +
> +    /* Read given slot and check it */
> +    if (luks_opts.has_slot) {
> +        slot = luks_opts.slot;
> +        if (slot < 0 || slot >= QCRYPTO_BLOCK_LUKS_NUM_KEY_SLOTS) {
> +            error_setg(errp,
> +                       "Given key slot %i is not supported by LUKS", slot);
> +             goto cleanup;

Off by 1 one indent

> +        }
> +    }
> +
> +    if (luks_opts.has_iter_time) {
> +        iter_time = luks_opts.iter_time;
> +    }
> +
> +    if (luks_opts.has_active && luks_opts.active == false) {
> +        active = false;
> +    }
> +
> +    if (active) {
> +
> +        /* Check that we are not overwriting an active slot */
> +        if (!force && slot != -1 &&
> +            qcrypto_block_luks_slot_active(luks, slot)) {
> +
> +            error_setg(errp, "Can't update an active key slot %i",
> +                       slot);
> +            goto cleanup;
> +        }
> +
> +        /* check that we have the passwords*/
> +        if (!luks_opts.has_key_secret) {
> +            error_setg(errp, "Can't add a key slot without a  password");
> +            goto cleanup;
> +        }
> +
> +        if (luks_opts.has_unlock_secret) {
> +            unlock_secret = luks_opts.unlock_secret;
> +        }
> +
> +        /* Read the old password */
> +        old_password = qcrypto_secret_lookup_as_utf8(unlock_secret, errp);
> +        if (!old_password) {
> +            goto cleanup;
> +        }
> +
> +        masterkey = g_new0(uint8_t, luks->header.master_key_len);
> +
> +        /* Retrieve the master key*/
> +        if (qcrypto_block_luks_find_key(block, old_password, masterkey,
> +                                        readfunc, opaque,
> +                                        errp) < 0) {
> +            error_append_hint(errp,
> +                              "unlock secret, doesn't unlock the image");

No need for the ',' in this msg I think.

> +            goto cleanup;
> +        }
> +
> +        /* Read the new password*/
> +        password = qcrypto_secret_lookup_as_utf8(luks_opts.key_secret, errp);
> +        if (!password) {
> +            goto cleanup;
> +        }
> +
> +        /* Find the new slot to write to */
> +        if (slot == -1) {
> +            slot = qcrypto_block_luks_find_free_keyslot(luks);
> +
> +            if (slot == -1) {
> +                error_setg(errp,
> +                           "Can't add a keyslot - all key slots are in use");
> +                goto cleanup;
> +
> +            }

Extra blank line

> +        }
> +
> +        /* Store the master key to the new slot */
> +        if (qcrypto_block_luks_store_key(block, slot, password, masterkey,
> +                                         iter_time, writefunc, opaque,
> +                                         errp)) {
> +


Extra blank line

> +            error_append_hint(errp, "Failed to store the keyslot %i", slot);
> +            goto cleanup;
> +        }
> +
> +    } else {
> +
> +        /* Check that we are not erasing last key slot */
> +        if (qcrypto_block_luks_count_active_slots(luks) <= 1) {
> +

Extra blank line(s)

> +            if (!force) {
> +                error_setg(errp, "Only one slot active - can't erase");
> +                goto cleanup;
> +            }
> +        }
> +
> +        if (slot != -1) {
> +            /* Check that we are not erasing an inactive slot */
> +            if (!qcrypto_block_luks_slot_active(luks, luks_opts.slot)) {
> +                if (!force) {
> +                    error_setg(errp, "Can't erase an inactive key slot %i",
> +                               slot);
> +                    goto cleanup;
> +                }
> +            }
> +
> +            /* Erase the given slot */
> +            if (qcrypto_block_luks_erase_key(block, slot,
> +                                             writefunc, opaque, errp)) {
> +                goto cleanup;
> +            }
> +
> +        } else {
> +            if (!luks_opts.has_key_secret) {
> +                error_setg(errp,
> +                           "To erase a keyslot you have to specify either 
> the"
> +                           "slot index or a password "
> +                           "(to erase all slots that match it)");
> +                goto cleanup;
> +            }
> +
> +            password = qcrypto_secret_lookup_as_utf8(luks_opts.key_secret,
> +                                                     errp);
> +            if (!password) {
> +                goto cleanup;
> +            }
> +
> +            ret = qcrypto_block_luks_erase_matching_keys(block, password,
> +                                                       readfunc, writefunc,
> +                                                       opaque, force, errp);
> +            if (ret == 0) {
> +                error_setg(errp,
> +                           "Didn't erase a keyslot, because no keyslots 
> match"
> +                           " the given password");
> +                ret = -EINVAL;
> +                goto cleanup;
> +            }
> +
> +            if (ret < 0) {
> +                goto cleanup;
> +            }
> +        }
> +    }
> +    ret = 0;
> +cleanup:
> +    return ret;
> +}
> +
> +
>  static int qcrypto_block_luks_get_info(QCryptoBlock *block,
>                                         QCryptoBlockInfo *info,
>                                         Error **errp)
> @@ -1569,7 +1928,9 @@ static int qcrypto_block_luks_get_info(QCryptoBlock 
> *block,
>  
>  static void qcrypto_block_luks_cleanup(QCryptoBlock *block)
>  {
> -    g_free(block->opaque);
> +    QCryptoBlockLUKS *luks = block->opaque;
> +    g_free(luks->secret);
> +    g_free(luks);
>  }
>  
>  
> @@ -1606,6 +1967,7 @@ qcrypto_block_luks_encrypt(QCryptoBlock *block,
>  const QCryptoBlockDriver qcrypto_block_driver_luks = {
>      .open = qcrypto_block_luks_open,
>      .create = qcrypto_block_luks_create,
> +    .amend = qcrypto_block_luks_amend_options,
>      .get_info = qcrypto_block_luks_get_info,
>      .cleanup = qcrypto_block_luks_cleanup,
>      .decrypt = qcrypto_block_luks_decrypt,
> -- 
> 2.17.2
> 

Regards,
Daniel
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