RFC Crypto kernel TLS socket

An approach for a kernel TLS socket.

Only the symmetric encryption / decryption is done in-kernel, as well as minimal framing handling. The handshake is kept in userspace, and the negotiated cipher / keys / IVs are then set on the algif_tls socket, which is then hooked in to a tcp socket using sk_write_space/sk_data_ready hooks.

If a non application-data TLS record is seen, it is left on the TCP socket and an error is returned on the ALG socket, and the record is left for userspace to manage. Userspace can't ignore the message, but could just close the socket.

TLS could potentially also be done directly on the TCP socket, but seemed a bit harder to work with the OOB data for non application_data messages, and the sockopts / CMSGS already exist for ALG sockets. The flip side is having to manage two fds in userspace.

Some reasons we're looking at this:

1) Access to sendfile/splice for CDN-type applications. We were inspired by Netflix exploring this in FreeBSD

https://people.freebsd.org/~rrs/asiabsd_2015_tls.pdf

For perf, this patch is almost on par with userspace OpenSSL. Currently there are some copies and allocs to support scatter/gather in aesni-intel_glue.c, but with some extra work to remove those (not included here), a sendfile() is faster than the equivalent userspace read/SSL_write using a 128k buffer by 2~7%.

2) Access to the unencrypted bytes in kernelspace. For example, Tom Herbert's kcm would need this

https://lwn.net/Articles/657999/

3) NIC offload. To support running aesni routines on the NIC instead of the processor, we would probably need enough of the framing interface put in kernel.

Dave Watson (2):
Crypto support aesni rfc5288
Crypto kernel tls socket

 arch/x86/crypto/aesni-intel_asm.S        |    6 +
 arch/x86/crypto/aesni-intel_avx-x86_64.S |    4 +
 arch/x86/crypto/aesni-intel_glue.c       |  105 ++-
 crypto/Kconfig                           |   12 +
 crypto/Makefile                          |    1 +
 crypto/algif_tls.c                       | 1233 ++++++++++++++++++++++++++++++
 6 files changed, 1334 insertions(+), 27 deletions(-)
 create mode 100644 crypto/algif_tls.c

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2.4.6