Besides adapting the components to the use of base/log.h, the patch
cleans up a few base headers, i.e., it removes unused includes from
root/component.h, specifically base/heap.h and
ram_session/ram_session.h. Hence, components that relied on the implicit
inclusion of those headers have to manually include those headers now.
While adjusting the log messages, I repeatedly stumbled over the problem
that printing char * arguments is ambiguous. It is unclear whether to
print the argument as pointer or null-terminated string. To overcome
this problem, the patch introduces a new type 'Cstring' that allows the
caller to express that the argument should be handled as null-terminated
string. As a nice side effect, with this type in place, the optional len
argument of the 'String' class could be removed. Instead of supplying a
pair of (char const *, size_t), the constructor accepts a 'Cstring'.
This, in turn, clears the way let the 'String' constructor use the new
output mechanism to assemble a string from multiple arguments (and
thereby getting rid of snprintf within Genode in the near future).
To enforce the explicit resolution of the char * ambiguity, the 'char *'
overload of the 'print' function is marked as deleted.
Issue #1987
The 'rump_cgd' server provides block level encryption for a block
session by employing the 'cgd(4)' device provided by the rumpkernel.
'rump_cgd' uses a Block_session to get access to an existing block
device and provides another Block_session to its clients. Each block
written or read by the client is transperently encrypted or decrypted
by the server.
For now 'rump_cgd' may only _configure_ a 'cgd' device but is unable
to generate a configuration. The used cipher is hardcoded to
_aes-cbc_ with a keysize of 256 bit. Furthermore the server is able to
serve one client only.
To ease the usage, its interface is modelled after the interface of
'cgdconfig(8)'. As implications thereof the key must have the same
format as used by 'cgdconfig'. That means the key is a base 64 encoded
string in which the first 4 bytes denote the actual length of the key
in bits (these 4 bytes are stored in big endian order).
Preparing a raw (e.g. without partition table) encrypted Ext2 disk
image is done by executing 'tool/rump':
! dd if=/dev/urandom of=/path/to/disk_image
! rump -c /path/to/disk_image # key is printed to stdout
! rump -c -k <key> -F ext2fs /path/to/disk_image
To use this disk image the following config snippet can be used:
! <start name="rump_cgd">
! <resource name="RAM" quantum="8M" />
! <provides><service name="Block"/></provides>
! <config action="configure">
! <params>
! <method>key</method>}
! <key>AAABAJhpB2Y2UvVjkFdlP4m44449Pi3A/uW211mkanSulJo8</key>
! </params>
! </config>
! <route>
! <service name="Block"> <child name="ahci"/> </service>
! <any-service> <parent/> <any-child/> </any-service>
! </route>
! </start>
the Block service provided by rump_cgd may be used by a file system
server in return:
! <start name="rump_fs">
! <resource name="RAM" quantum="16M"/>
! <provides><service name="File_system"/></provides>
! <config fs="ext2fs">
! <policy label="" root="/" writeable="yes"/>
! </config>
! <route>
! <service name="Block"> <child name="rump_cgd"/> </service>
! <any-service> <parent/> <any-child/> </any-service>
! </route>
! </start>
Since 'tool/rump' just utilizes the rumpkernel running on the host
system to do its duty there is a script called 'tool/cgdconf' that
extracts the key from a 'cgdconfig(8)' generated configuration file
and also is able to generade such a file from a given key. Thereby
the interoperabilty between 'rump_cgd' and the general rumpkernel
based tools is secured.
