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Olga Kornievskaia df513a7711 SUNRPC: fix krb5p mount to provide large enough buffer in rq_rcvsize
Ever since commit 2c94b8eca1 ("SUNRPC: Use au_rslack when computing
reply buffer size"). It changed how "req->rq_rcvsize" is calculated. It
used to use au_cslack value which was nice and large and changed it to
au_rslack value which turns out to be too small.

Since 5.1, v3 mount with sec=krb5p fails against an Ontap server
because client's receive buffer it too small.

For gss krb5p, we need to account for the mic token in the verifier,
and the wrap token in the wrap token.

RFC 4121 defines:
mic token
Octet no   Name        Description
         --------------------------------------------------------------
         0..1     TOK_ID     Identification field.  Tokens emitted by
                             GSS_GetMIC() contain the hex value 04 04
                             expressed in big-endian order in this
                             field.
         2        Flags      Attributes field, as described in section
                             4.2.2.
         3..7     Filler     Contains five octets of hex value FF.
         8..15    SND_SEQ    Sequence number field in clear text,
                             expressed in big-endian order.
         16..last SGN_CKSUM  Checksum of the "to-be-signed" data and
                             octet 0..15, as described in section 4.2.4.

that's 16bytes (GSS_KRB5_TOK_HDR_LEN) + chksum

wrap token
Octet no   Name        Description
         --------------------------------------------------------------
          0..1     TOK_ID    Identification field.  Tokens emitted by
                             GSS_Wrap() contain the hex value 05 04
                             expressed in big-endian order in this
                             field.
          2        Flags     Attributes field, as described in section
                             4.2.2.
          3        Filler    Contains the hex value FF.
          4..5     EC        Contains the "extra count" field, in big-
                             endian order as described in section 4.2.3.
          6..7     RRC       Contains the "right rotation count" in big-
                             endian order, as described in section
                             4.2.5.
          8..15    SND_SEQ   Sequence number field in clear text,
                             expressed in big-endian order.
          16..last Data      Encrypted data for Wrap tokens with
                             confidentiality, or plaintext data followed
                             by the checksum for Wrap tokens without
                             confidentiality, as described in section
                             4.2.4.

Also 16bytes of header (GSS_KRB5_TOK_HDR_LEN), encrypted data, and cksum
(other things like padding)

RFC 3961 defines known cksum sizes:
Checksum type              sumtype        checksum         section or
                                value            size         reference
   ---------------------------------------------------------------------
   CRC32                            1               4           6.1.3
   rsa-md4                          2              16           6.1.2
   rsa-md4-des                      3              24           6.2.5
   des-mac                          4              16           6.2.7
   des-mac-k                        5               8           6.2.8
   rsa-md4-des-k                    6              16           6.2.6
   rsa-md5                          7              16           6.1.1
   rsa-md5-des                      8              24           6.2.4
   rsa-md5-des3                     9              24             ??
   sha1 (unkeyed)                  10              20             ??
   hmac-sha1-des3-kd               12              20            6.3
   hmac-sha1-des3                  13              20             ??
   sha1 (unkeyed)                  14              20             ??
   hmac-sha1-96-aes128             15              20         [KRB5-AES]
   hmac-sha1-96-aes256             16              20         [KRB5-AES]
   [reserved]                  0x8003               ?         [GSS-KRB5]

Linux kernel now mainly supports type 15,16 so max cksum size is 20bytes.
(GSS_KRB5_MAX_CKSUM_LEN)

Re-use already existing define of GSS_KRB5_MAX_SLACK_NEEDED that's used
for encoding the gss_wrap tokens (same tokens are used in reply).

Fixes: 2c94b8eca1 ("SUNRPC: Use au_rslack when computing reply buffer size")
Signed-off-by: Olga Kornievskaia <kolga@netapp.com>
Reviewed-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
2020-03-26 10:51:01 -04:00
arch Two fixes for x86: 2020-03-15 12:52:56 -07:00
block block: Fix partition support for host aware zoned block devices 2020-03-12 07:54:39 -06:00
certs certs: Add wrapper function to check blacklisted binary hash 2019-11-12 12:25:50 +11:00
crypto Merge branch 'next-integrity' of git://git.kernel.org/pub/scm/linux/kernel/git/zohar/linux-integrity 2020-02-20 15:15:16 -08:00
Documentation A single commit to handle an erratum in Cavium ThunderX to prevent access 2020-03-15 13:15:16 -07:00
drivers A single commit to handle an erratum in Cavium ThunderX to prevent access 2020-03-15 13:15:16 -07:00
fs NFS: Don't specify NFS version in "UDP not supported" error 2020-03-25 08:46:34 -04:00
include SUNRPC: Remove xdr_buf_read_mic() 2020-03-16 10:18:45 -04:00
init Tracing updates: 2020-02-26 10:34:42 -08:00
ipc Revert "ipc,sem: remove uneeded sem_undo_list lock usage in exit_sem()" 2020-02-21 11:22:15 -08:00
kernel Fix for yet another subtle futex issue. The futex code used ihold() to 2020-03-15 12:55:52 -07:00
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mm Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2020-03-12 16:19:19 -07:00
net SUNRPC: fix krb5p mount to provide large enough buffer in rq_rcvsize 2020-03-26 10:51:01 -04:00
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sound ASoC: Fixes for v5.6 2020-03-07 07:24:36 +01:00
tools A pile of perf fixes: 2020-03-15 12:50:15 -07:00
usr Kbuild updates for v5.6 (2nd) 2020-02-09 16:05:50 -08:00
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.mailmap A handful of small documentation fixes that wandered in. 2020-02-07 13:03:10 -08:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
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Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.