Use const with some read-only buffers in opencrypto APIs.

[jhb]

Summary

Use const with some read-only buffers in opencrypto APIs.

• Mark the source buffer for a copyback operation as const in the kernel API.
• Use const with input-only buffers in crypto ioctl structures used with /dev/crypto.

Test Plan

• passes make tinderbox
• have tested IPSec + /dev/crypto access (via a testing tool that compares the results of crypto operations on /dev/crypto against OpenSSL's software implementation) against cryptosoft, aesni(4), and a driver for the Chelsio T6 crypto engine

[jmg]

looks fine, have you verified that the tests in tests/sys/opencrypto pass? they are not present in your test plan.

Also, is your testing tool in the tree?

[jhb]

The testing tool is in the branch https://github.com/freebsd/freebsd/compare/master...bsdjhb:cryptocheck. (These changes are also in that branch, and my intention is to pull smaller bits out one at a time for review.) I will run the other tests, though they are currently still hardcoded for aesni0.

[jhb]

The python tests pass.

[delphij]

No objection from secteam@ (if we were blocking).