84 lines
3.7 KiB
Plaintext
84 lines
3.7 KiB
Plaintext
crypto-API support for z990 Message Security Assist (MSA) instructions
|
|
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
|
|
|
|
AUTHOR: Thomas Spatzier (tspat@de.ibm.com)
|
|
|
|
|
|
1. Introduction crypto-API
|
|
~~~~~~~~~~~~~~~~~~~~~~~~~~
|
|
See Documentation/crypto/api-intro.txt for an introduction/description of the
|
|
kernel crypto API.
|
|
According to api-intro.txt support for z990 crypto instructions has been added
|
|
in the algorithm api layer of the crypto API. Several files containing z990
|
|
optimized implementations of crypto algorithms are placed in the
|
|
arch/s390/crypto directory.
|
|
|
|
|
|
2. Probing for availability of MSA
|
|
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
|
|
It should be possible to use Kernels with the z990 crypto implementations both
|
|
on machines with MSA available an on those without MSA (pre z990 or z990
|
|
without MSA). Therefore a simple probing mechanisms has been implemented:
|
|
In the init function of each crypto module the availability of MSA and of the
|
|
respective crypto algorithm in particular will be tested. If the algorithm is
|
|
available the module will load and register its algorithm with the crypto API.
|
|
|
|
If the respective crypto algorithm is not available, the init function will
|
|
return -ENOSYS. In that case a fallback to the standard software implementation
|
|
of the crypto algorithm must be taken ( -> the standard crypto modules are
|
|
also build when compiling the kernel).
|
|
|
|
|
|
3. Ensuring z990 crypto module preference
|
|
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
|
|
If z990 crypto instructions are available the optimized modules should be
|
|
preferred instead of standard modules.
|
|
|
|
3.1. compiled-in modules
|
|
~~~~~~~~~~~~~~~~~~~~~~~~
|
|
For compiled-in modules it has to be ensured that the z990 modules are linked
|
|
before the standard crypto modules. Then, on system startup the init functions
|
|
of z990 crypto modules will be called first and query for availability of z990
|
|
crypto instructions. If instruction is available, the z990 module will register
|
|
its crypto algorithm implementation -> the load of the standard module will fail
|
|
since the algorithm is already registered.
|
|
If z990 crypto instruction is not available the load of the z990 module will
|
|
fail -> the standard module will load and register its algorithm.
|
|
|
|
3.2. dynamic modules
|
|
~~~~~~~~~~~~~~~~~~~~
|
|
A system administrator has to take care of giving preference to z990 crypto
|
|
modules. If MSA is available appropriate lines have to be added to
|
|
/etc/modprobe.conf.
|
|
|
|
Example: z990 crypto instruction for SHA1 algorithm is available
|
|
|
|
add the following line to /etc/modprobe.conf (assuming the
|
|
z990 crypto modules for SHA1 is called sha1_z990):
|
|
|
|
alias sha1 sha1_z990
|
|
|
|
-> when the sha1 algorithm is requested through the crypto API
|
|
(which has a module autoloader) the z990 module will be loaded.
|
|
|
|
TBD: a userspace module probin mechanism
|
|
something like 'probe sha1 sha1_z990 sha1' in modprobe.conf
|
|
-> try module sha1_z990, if it fails to load load standard module sha1
|
|
the 'probe' statement is currently not supported in modprobe.conf
|
|
|
|
|
|
4. Currently implemented z990 crypto algorithms
|
|
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
|
|
The following crypto algorithms with z990 MSA support are currently implemented.
|
|
The name of each algorithm under which it is registered in crypto API and the
|
|
name of the respective module is given in square brackets.
|
|
|
|
- SHA1 Digest Algorithm [sha1 -> sha1_z990]
|
|
- DES Encrypt/Decrypt Algorithm (64bit key) [des -> des_z990]
|
|
- Tripple DES Encrypt/Decrypt Algorithm (128bit key) [des3_ede128 -> des_z990]
|
|
- Tripple DES Encrypt/Decrypt Algorithm (192bit key) [des3_ede -> des_z990]
|
|
|
|
In order to load, for example, the sha1_z990 module when the sha1 algorithm is
|
|
requested (see 3.2.) add 'alias sha1 sha1_z990' to /etc/modprobe.conf.
|
|
|