[PATCH v1 0/7] kNFSD Encrypted Filehandles

[Benjamin Coddington <bcodding@hammerspace.com>]

In order to harden kNFSD against various filehandle manipulation techniques
the following patches implement a method of reversibly encrypting filehandle
contents.

Using the kernel's skcipher AES-CBC, filehandles are encrypted by firstly
hashing the fileid using the fsid as a salt, then using the hashed fileid as
the first block to finally hash the fsid.

The first attempts at this used stack-allocated buffers, but I ran into many
memory alignment problems on my arm64 machine that sent me back to using
GFP_KERNEL allocations (here's to you /include/linux/scatterlist.h:210).  In
order to avoid constant allocation/freeing, the buffers are allocated once
for every knfsd thread.  If anyone has suggestions for reducing the number
of buffers required and their memcpy() operations, I am all ears.

Currently the code overloads filehandle's auth_type byte.  This seems
appropriate for this purpose, but this implementation does not actually
reject unencrypted filehandles on an export that is giving out encrypted
ones.  I expect we'll want to tighten this up in a future version.

Comments and critique welcome.

Benjamin Coddington (7):
  nfsd: Convert export flags to use BIT() macro
  nfsd: Add a symmetric-key cipher for encrypted filehandles
  nfsd/sunrpc: add per-thread crypto context pointer
  NFSD: Add a per-knfsd reusable encfh_buf
  NFSD/export: Add encrypt_fh export option
  NFSD: Add filehandle crypto functions and helpers
  NFSD: Enable filehandle encryption

 Documentation/netlink/specs/nfsd.yaml |  12 ++
 fs/nfsd/export.c                      |   7 +-
 fs/nfsd/localio.c                     |   2 +-
 fs/nfsd/lockd.c                       |   2 +-
 fs/nfsd/netlink.c                     |  15 +++
 fs/nfsd/netlink.h                     |   1 +
 fs/nfsd/netns.h                       |   1 +
 fs/nfsd/nfs3proc.c                    |  10 +-
 fs/nfsd/nfs3xdr.c                     |  14 +-
 fs/nfsd/nfs4proc.c                    |  10 +-
 fs/nfsd/nfs4xdr.c                     |  14 +-
 fs/nfsd/nfsctl.c                      |  40 +++++-
 fs/nfsd/nfsfh.c                       | 179 +++++++++++++++++++++++++-
 fs/nfsd/nfsfh.h                       |  26 +++-
 fs/nfsd/nfsproc.c                     |   8 +-
 fs/nfsd/trace.h                       |  19 +++
 include/linux/sunrpc/svc.h            |  12 +-
 include/uapi/linux/nfsd/export.h      |  36 +++---
 include/uapi/linux/nfsd_netlink.h     |   2 +
 net/sunrpc/svc.c                      |   1 +
 20 files changed, 356 insertions(+), 55 deletions(-)

-- 
2.50.1