[PATCH v9 0/2] crypto: AF_ALG: add AEAD and RNG support

[Stephan Mueller]

Hi,

This patch set adds AEAD and RNG support to the AF_ALG interface
exported by the kernel crypto API. By extending AF_ALG with AEAD and RNG
support, all cipher types the kernel crypto API allows access to are
now accessible from userspace.

Both, AEAD and RNG implementations are stand-alone and do not depend
other AF_ALG interfaces (like hash or skcipher).

The AEAD implementation uses the same approach as provided with
skcipher by offering the following interfaces:

	* sendmsg and recvmsg interfaces allowing multiple
	  invocations supporting a threaded user space. To support
	  multi-threaded user space, kernel-side buffering
	  is implemented similarly to skcipher.

	* splice / vmsplice interfaces allowing a zero-copy
	  invocation

The RNG interface only implements the recvmsg interface as
zero-copy is not applicable.

The new AEAD and RNG interfaces are fully tested with the test application
provided at [1]. That test application exercises all newly added user space
interfaces. The testing covers:

	* use of the sendmsg/recvmsg interface

	* use of the splice / vmsplice interface

	* invocation of all AF_ALG types (aead, rng, skcipher, hash)

	* using all types of operation (encryption, decryption, keyed MD,
	  MD, random numbers, AEAD decryption with positive and negative
	  authentication verification)

	* stress testing by running all tests for 30 minutes in an
	  endless loop

	* test execution on 64 bit and 32 bit

[1] http://www.chronox.de/libkcapi.html

Changes v2:
* rebase to current cryptodev-2.6 tree
* use memzero_explicit to zeroize AEAD associated data
* use sizeof for determining length of AEAD associated data
* update algif_rng.c covering all suggestions from Daniel Borkmann
  <dborkman@xxxxxxxxxx>
* addition of patch 9: add digestsize interface for hashes
* addition of patch to update documentation covering the userspace interface
* change numbers of getsockopt options: separate them from sendmsg interface
  definitions

Changes v3:
* remove getsockopt interface
* AEAD: associated data is set prepended to the plain/ciphertext
* AEAD: allowing arbitrary associated data lengths
* remove setkey patch as protection was already in the existing code

Changes v4:
* stand-alone implementation of AEAD
* testing of all interfaces offered by AEAD
* stress testing of AEAD and RNG

Changes v5:
* AEAD: add outer while(size) loop in aead_sendmsg to ensure all data is
  copied into the kernel (reporter Herbert Xu)
* AEAD: aead_sendmsg bug fix: change size -= len; to size -= plen;
* AF_ALG / AEAD: add aead_setauthsize and associated extension to
  struct af_alg_type as well as alg_setsockopt (reporter Herbert Xu)
* RNG: rng_recvmsg: use 128 byte stack variable for output of RNG instead
  of ctx->result (reporter Herbert Xu)
* RNG / AF_ALG: allow user space to seed RNG via setsockopt
* RNG: rng_recvmsg bug fix: use genlen as result variable for
  crypto_rng_get_bytes as previously no negative errors were obtained
* AF_ALG: alg_setop: zeroize buffer before free

Changes v6:
* AEAD/RNG: port to 3.19-rc1 with the iov_iter handling
* RNG: use the setkey interface to obtain the seed and drop the patch adding
  a separate reseeding interface
* extract the zeroization patch for alg_setkey into a stand-alone patch
  submission
* fix bug in aead_sufficient_data (reporter Herbert Xu)
* testing of all interfaces with test application provided with libkcapi version
  0.6.2

Changes v7:
* AEAD: aead_recvmsg: change error code from ENOMEM to EINVAL
* AEAD: drop aead_readable/aead_sufficient_data and only use ctx->more to decide
  whether the read side shall become active. This change requires that the
  patch for crypto_aead_decrypt ensuring that the ciphertext contains the
  authentication tag was added -- see https://lkml.org/lkml/2014/12/30/200.
  Otherwise, user space can trigger a kernel crash.
* RNG: patch dropped as it was applied
* AEAD: port Kconfig/Makefile patch forward to current code base

Changes v8:
* Removed check for aead_assoclen in aead_sendmsg
* Fix endless loop bug in aead_sendmsg (check for sgl->cur > ALG_MAX_PAGES in
  while condition removed -- this condition is checked within the loop already)
* Resurrect aead_sufficient_data and call it in aead_sendmsg, aead_sendpage to
  notify caller about wrong invocation
* Re-add aead_sufficient_data to aead_recvmsg to verify user input data before
  using them to ensure the kernel protects against malicious parameters
* Allow arbitrary size of AD (i.e. up to the maximum buffer size of
  ALG_MAX_PAGES)
* When aead_recvmsg receives an error from decryption, release all pages if the
  error is EBADMSG -- this error implies that a proper decryption was performed
  but the integrity of the message is lost. This error is considered to be a
  valid decryption result.
* Add test cases for sendmsg and splice interface to test large AD sizes (in
  case of sendmsg, use 65504 bytes AD and 32 bytes plaintext; in case of splice
  use 15 pages AD and 32 bytes in the 16th page for plaintext). See [1] for
  updated test case.

Changes v9:
* if socket is not writable during sendmsg/sendpage due to insufficient memory
  and a recvmsg operation is forced, inform userspace about truncated operation
  via MSG_TRUNC
* use -EMSGSIZE in case insufficient data was provided in sendmsg/sendpage
* release all buffers in case insufficient data was provided in sendmsg/sendpage
* bug fix in sendmsg: when a new page is allocated, reset sg->offset to 0 --
  the error is visible with the new tests in [1] when using the -d flag
  with the test application

Stephan Mueller (2):
  crypto: AF_ALG: add AEAD support
  crypto: AF_ALG: enable AEAD interface compilation

 crypto/Kconfig      |   9 +
 crypto/Makefile     |   1 +
 crypto/algif_aead.c | 679 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 689 insertions(+)
 create mode 100644 crypto/algif_aead.c

-- 
2.1.0


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