VNCONFIG(8) BSD System Manager's Manual VNCONFIG(8)
vnconfig - configure vnode disks for file swapping or pseudo file systems
vnconfig [-c] [-vkr] [-f keyfile] rawdev regular_file vnconfig -u [-v] rawdev vnconfig -l [rawdev] vnconfig -K algorithm -f keyfile
The vnconfig command configures vnode pseudo disk devices. It will asso- ciate (or disassociate) the special file rawdev with the regular file regular_file allowing the latter to be accessed as though it were a disk. Hence a regular file within the filesystem can be used for swapping or can contain a filesystem that is mounted in the name space. Both tradi- tional devices, vnd, and the cache-coherent devices, svnd, are configured through vnconfig. If you read the regular file while using svnd, you need to mount the svnd with the mount option sync to ensure consistency in the buffer cache. For normal operation this is not necessary. The options are as follows: -c Configures the device. If successful, references to rawdev will access the contents of regular_file. This is the default opera- tion. -f keyfile Instead of an encryption key read from stdin, an ASN.1 octet string will be decoded from the PEM format keyfile. This option implies -k. -k Associate an encryption key with the device. All data will be en- crypted using the Blowfish cipher before it is written to the disk. Encryption only works with svnd, not with vnd. -K algorithm Generate a PEM format keyfile containing an encrypted ASN.1 octet string which can be used as keyfile for further invocations of vnconfig -kf. This is incompatible with the -K rounds / -S saltfile method invented in OpenBSD 4.2. If the -k option is also used, the system will convert an old (plain password) encryption key to a keyfile by first asking (twice) for the plaintext password, then (twice) for the PEM passphrase with which to protect the keyfile (consisting of an encoded version of the old plaintext password). This can be used to migrate old encrypted volumes using the OpenBSD blowfish (bf- cbc) format to the new keyfile-based scheme, which supports changing the user (PEM) passphrase without needing to re-encrypt the actual data. If the -k option is not used, vnconfig will create a keyfile con- sisting of 448 random bits (for use with the new-style bf-cbc al- gorithm - other algorithms will follow and use different for- mats), ask (twice) for a PEM passphrase with which the newly created keyfile is to be protected, which can be changed by the user without needing to re-encrypt the actual data, then save the keyfile just created to disc. The algorithm can be chosen from the default openssltool(1) list; see below for an example. -l List the vnd devices and indicate which ones are in use. If a specific rawdev is given, then only that one will be described. -r If the kernel supports it, don't write to the underlying file. This is supported since MirOS #7. -u Unconfigures the device. -v Print messages to stdout describing actions taken. If no action option is given, -c is assumed.
Configure the vnode disk svnd0 (all of its partitions become usable): # vnconfig svnd0 /tmp/diskimage Unconfigure the same device: # vnconfig -u svnd0 Show a list of supported Cipher Types: $ openssl enc - Create an encrypted image and a keyfile: $ dd if=/dev/arandom of=/tmp/foo.ima bs=1048576 count=16 $ vnconfig -K AES-256-CBC -f /tmp/foo.skf Use an encrypted image with a keyfile: # vnconfig -f /tmp/foo.skf svnd0 /tmp/foo.ima
openssl(1), openssltool(1), arc4random(3), blowfish(3), vnd(4), mount(8), swapon(8), umount(8)
Support for external keyfiles was added in MirOS #9.
This command should really be named vndconfig. Currently, only bf-cbc (Blowfish) encryption in an OpenBSD compatible format is available. Support for AES (including VIA C3 hardware accelera- tion) is planned. Configuring a block device, such as /dev/wd0e, as regular_file will result in very bad I/O performance due to the use of synchronous (reli- able) writes, even if the inner filesystem is mounted async or with sof- tupdates. Character special devices cannot be used at all. This is a bug inherited from OpenBSD. MirOS BSD #10-current March 29, 2014 1
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