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Scott reports SUNRPC self-test failures regarding the output IV on arm64
when using the SIMD accelerated implementation of AES in CBC mode with
ciphertext stealing ("cts(cbc(aes))" in crypto API speak).
These failures are the result of the fact that, while RFC 3962 does
specify what the output IV should be and includes test vectors for it,
the general concept of an output IV is poorly defined, and generally,
not specified by the various algorithms implemented by the crypto API.
Only algorithms that support transparent chaining (e.g., CBC mode on a
block boundary) have requirements on the output IV, but ciphertext
stealing (CTS) is fundamentally about how to encapsulate CBC in a way
where the length of the entire message may not be an integral multiple
of the cipher block size, and the concept of an output IV does not exist
here because it has no defined purpose past the end of the message.
The generic CTS template takes advantage of this chaining capability of
the CBC implementations, and as a result, happens to return an output
IV, simply because it passes its IV buffer directly to the encapsulated
CBC implementation, which operates on full blocks only, and always
returns an IV. This output IV happens to match how RFC 3962 defines it,
even though the CTS template itself does not contain any output IV logic
whatsoever, and, for this reason, lacks any test vectors that exercise
this accidental output IV generation.
The arm64 SIMD implementation of cts(cbc(aes)) does not use the generic
CTS template at all, but instead, implements the CBC mode and ciphertext
stealing directly, and therefore does not encapsule a CBC implementation
that returns an output IV in the same way. The arm64 SIMD implementation
complies with the specification and passes all internal tests, but when
invoked by the SUNRPC code, fails to produce the expected output IV and
causes its selftests to fail.
Given that the output IV is defined as the penultimate block (where the
final block may smaller than the block size), we can quite easily derive
it in the caller by copying the appropriate slice of ciphertext after
encryption.
Cc: Trond Myklebust <trond.myklebust@hammerspace.com>
Cc: Anna Schumaker <anna@kernel.org>
Cc: Chuck Lever <chuck.lever@oracle.com>
Cc: Jeff Layton <jlayton@kernel.org>
Reported-by: Scott Mayhew <smayhew@redhat.com>
Tested-by: Scott Mayhew <smayhew@redhat.com>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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The get_expiry() function currently returns a timestamp, and uses the
special return value of 0 to indicate an error.
Unfortunately this causes a problem when 0 is the correct return value.
On a system with no RTC it is possible that the boot time will be seen
to be "3". When exportfs probes to see if a particular filesystem
supports NFS export it tries to cache information with an expiry time of
"3". The intention is for this to be "long in the past". Even with no
RTC it will not be far in the future (at most a second or two) so this
is harmless.
But if the boot time happens to have been calculated to be "3", then
get_expiry will fail incorrectly as it converts the number to "seconds
since bootime" - 0.
To avoid this problem we change get_expiry() to report the error quite
separately from the expiry time. The error is now the return value.
The expiry time is reported through a by-reference parameter.
Reported-by: Jerry Zhang <jerry@skydio.com>
Tested-by: Jerry Zhang <jerry@skydio.com>
Signed-off-by: NeilBrown <neilb@suse.de>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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Scott reports that when the new GSS krb5 Kunit tests are built as
a separate module and loaded, the RFC 6803 and RFC 8009 checksum
tests all fail, even though they pass when run under kunit.py.
It appears that passing a buffer backed by static const memory to
gss_krb5_checksum() is a problem. A printk in checksum_case() shows
the correct plaintext, but by the time the buffer has been converted
to a scatterlist and arrives at checksummer(), it contains all
zeroes.
Replacing this buffer with one that is dynamically allocated fixes
the issue.
Reported-by: Scott Mayhew <smayhew@redhat.com>
Fixes: 02142b2ca8fc ("SUNRPC: Add checksum KUnit tests for the RFC 6803 encryption types")
Tested-by: Scott Mayhew <smayhew@redhat.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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The usage_data[] array in rfc6803_encrypt_case() is uninitialised, so clear
it as it may cause the tests to fail otherwise.
Fixes: b958cff6b27b ("SUNRPC: Add encryption KUnit tests for the RFC 6803 encryption types")
Link: https://lore.kernel.org/r/380323.1681314997@warthog.procyon.org.uk/
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Chuck Lever <chuck.lever@oracle.com>
cc: Scott Mayhew <smayhew@redhat.com>
cc: Herbert Xu <herbert@gondor.apana.org.au>
cc: linux-nfs@vger.kernel.org
cc: linux-crypto@vger.kernel.org
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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Anna says:
> KASAN reports [...] a slab-out-of-bounds in gss_krb5_checksum(),
> and it can cause my client to panic when running cthon basic
> tests with krb5p.
> Running faddr2line gives me:
>
> gss_krb5_checksum+0x4b6/0x630:
> ahash_request_free at
> /home/anna/Programs/linux-nfs.git/./include/crypto/hash.h:619
> (inlined by) gss_krb5_checksum at
> /home/anna/Programs/linux-nfs.git/net/sunrpc/auth_gss/gss_krb5_crypto.c:358
My diagnosis is that the memcpy() at the end of gss_krb5_checksum()
reads past the end of the buffer containing the checksum data
because the callers have ignored gss_krb5_checksum()'s API contract:
* Caller provides the truncation length of the output token (h) in
* cksumout.len.
Instead they provide the fixed length of the hmac buffer. This
length happens to be larger than the value returned by
crypto_ahash_digestsize().
Change these errant callers to work like krb5_etm_{en,de}crypt().
As a defensive measure, bound the length of the byte copy at the
end of gss_krb5_checksum().
Kunit sez:
Testing complete. Ran 68 tests: passed: 68
Elapsed time: 81.680s total, 5.875s configuring, 75.610s building, 0.103s running
Reported-by: Anna Schumaker <schumaker.anna@gmail.com>
Fixes: 8270dbfcebea ("SUNRPC: Obscure Kerberos integrity keys")
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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Unable to handle kernel paging request at virtual address 73657420 when execute
[73657420] *pgd=00000000
Internal error: Oops: 80000005 [#1] ARM
CPU: 0 PID: 1 Comm: swapper Tainted: G N 6.2.0-rc7-00133-g373f26a81164-dirty #9
Hardware name: Generic DT based system
PC is at 0x73657420
LR is at kunit_run_tests+0x3e0/0x5f4
On x86 with GCC 12, the missing array terminators did not seem to
matter. Other platforms appear to be more picky.
Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>
Tested-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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Allow the new GSS Kerberos encryption type test suites to run
outside of the kunit infrastructure. Replace the assertion that
fires when lookup_enctype() so that the case is skipped instead of
failing outright.
Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>
Tested-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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I'm guessing that the warning fired because there's some code path
that is called on module unload where the gss_krb5_enctypes file
was never set up.
name 'gss_krb5_enctypes'
WARNING: CPU: 0 PID: 6187 at fs/proc/generic.c:712 remove_proc_entry+0x38d/0x460 fs/proc/generic.c:712
destroy_krb5_enctypes_proc_entry net/sunrpc/auth_gss/svcauth_gss.c:1543 [inline]
gss_svc_shutdown_net+0x7d/0x2b0 net/sunrpc/auth_gss/svcauth_gss.c:2120
ops_exit_list+0xb0/0x170 net/core/net_namespace.c:169
setup_net+0x9bd/0xe60 net/core/net_namespace.c:356
copy_net_ns+0x320/0x6b0 net/core/net_namespace.c:483
create_new_namespaces+0x3f6/0xb20 kernel/nsproxy.c:110
copy_namespaces+0x410/0x500 kernel/nsproxy.c:179
copy_process+0x311d/0x76b0 kernel/fork.c:2272
kernel_clone+0xeb/0x9a0 kernel/fork.c:2684
__do_sys_clone+0xba/0x100 kernel/fork.c:2825
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
Reported-by: syzbot+04a8437497bcfb4afa95@syzkaller.appspotmail.com
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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With the KUnit infrastructure recently added, we are free to define
other unit tests particular to our implementation. As an example,
I've added a self-test that encrypts then decrypts a string, and
checks the result.
Tested-by: Scott Mayhew <smayhew@redhat.com>
Reviewed-by: Simo Sorce <simo@redhat.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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RFC 8009 provides sample encryption results. Add KUnit tests to
ensure our implementation derives the expected results for the
provided sample input.
I hate how large this test is, but using non-standard key usage
values means rfc8009_encrypt_case() can't simply reuse ->import_ctx
to allocate and key its ciphers; and the test provides its own
confounders, which means krb5_etm_encrypt() can't be used directly.
Tested-by: Scott Mayhew <smayhew@redhat.com>
Reviewed-by: Simo Sorce <simo@redhat.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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RFC 8009 provides sample checksum results. Add KUnit tests to ensure
our implementation derives the expected results for the provided
sample input.
Tested-by: Scott Mayhew <smayhew@redhat.com>
Reviewed-by: Simo Sorce <simo@redhat.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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RFC 8009 provides sample key derivation results, so Kunit tests are
added to ensure our implementation derives the expected keys for the
provided sample input.
Tested-by: Scott Mayhew <smayhew@redhat.com>
Reviewed-by: Simo Sorce <simo@redhat.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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Add tests for the new-to-RPCSEC Camellia cipher.
Tested-by: Scott Mayhew <smayhew@redhat.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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Test the new-to-RPCSEC CMAC digest algorithm.
Tested-by: Scott Mayhew <smayhew@redhat.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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The Camellia enctypes use a new KDF, so add some tests to ensure it
is working properly.
Tested-by: Scott Mayhew <smayhew@redhat.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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Add Kunit tests for ENCTYPE_AES128_CTS_HMAC_SHA1_96. The test
vectors come from RFC 3962 Appendix B.
Tested-by: Scott Mayhew <smayhew@redhat.com>
Reviewed-by: Simo Sorce <simo@redhat.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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RFC 3961 Appendix A provides tests for the KDF specified in that
document as well as other parts of Kerberos. The other three usage
scenarios in Section 10 are not implemented by the Linux kernel's
RPCSEC GSS Kerberos 5 mechanism, so tests are not added for those.
Tested-by: Scott Mayhew <smayhew@redhat.com>
Reviewed-by: Simo Sorce <simo@redhat.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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I plan to add KUnit tests that will need enctype profile
information. Export the enctype profile lookup function.
Tested-by: Scott Mayhew <smayhew@redhat.com>
Reviewed-by: Simo Sorce <simo@redhat.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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The Kerberos RFCs provide test vectors to verify the operation of
an implementation. Introduce a KUnit test framework to exercise the
Linux kernel's implementation of Kerberos.
Start with test cases for the RFC 3961-defined n-fold function. The
sample vectors for that are found in RFC 3961 Section 10.
Run the GSS Kerberos 5 mechanism's unit tests with this command:
$ ./tools/testing/kunit/kunit.py run \
--kunitconfig ./net/sunrpc/.kunitconfig
Tested-by: Scott Mayhew <smayhew@redhat.com>
Reviewed-by: Simo Sorce <simo@redhat.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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The goal is to leave only protocol-defined items in gss_krb5.h so
that it can be easily replaced by a generic header. Implementation
specific items are moved to the new internal header.
Tested-by: Scott Mayhew <smayhew@redhat.com>
Reviewed-by: Simo Sorce <simo@redhat.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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Add the RFC 6803 encryption types to the string of integers that is
reported to gssd during upcalls. This enables gssd to utilize keys
with these encryption types when support for them is built into the
kernel.
Tested-by: Scott Mayhew <smayhew@redhat.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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The Camellia enctypes use the KDF_FEEDBACK_CMAC Key Derivation
Function defined in RFC 6803 Section 3.
Tested-by: Scott Mayhew <smayhew@redhat.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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RFC 6803 defines two encryption types that use Camellia ciphers (RFC
3713) and CMAC digests. Implement support for those in SunRPC's GSS
Kerberos 5 mechanism.
There has not been an explicit request to support these enctypes.
However, this new set of enctypes provides a good alternative to the
AES-SHA1 enctypes that are to be deprecated at some point.
As this implementation is still a "beta", the default is to not
build it automatically.
Tested-by: Scott Mayhew <smayhew@redhat.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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Add the RFC 8009 encryption types to the string of integers that is
reported to gssd during upcalls. This enables gssd to utilize keys
with these encryption types when support for them is built into the
kernel.
Link: https://bugzilla.linux-nfs.org/show_bug.cgi?id=400
Tested-by: Scott Mayhew <smayhew@redhat.com>
Reviewed-by: Simo Sorce <simo@redhat.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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RFC 8009 enctypes use different crypt formulae than previous
Kerberos 5 encryption types. Section 1 of RFC 8009 explains the
reason for this change:
> The new types conform to the framework specified in [RFC3961],
> but do not use the simplified profile, as the simplified profile
> is not compliant with modern cryptographic best practices such as
> calculating Message Authentication Codes (MACs) over ciphertext
> rather than plaintext.
Add new .encrypt and .decrypt functions to handle this variation.
The new approach described above is referred to as Encrypt-then-MAC
(or EtM). Hence the names of the new functions added here are
prefixed with "krb5_etm_".
A critical second difference with previous crypt formulae is that
the cipher state is included in the computed HMAC. Note however that
for RPCSEC, the initial cipher state is easy to compute on both
initiator and acceptor because it is always all zeroes.
Tested-by: Scott Mayhew <smayhew@redhat.com>
Reviewed-by: Simo Sorce <simo@redhat.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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The RFC 8009 encryption types use a different key derivation
function than the RFC 3962 encryption types. The new key derivation
function is defined in Section 3 of RFC 8009.
Tested-by: Scott Mayhew <smayhew@redhat.com>
Reviewed-by: Simo Sorce <simo@redhat.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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Fill in entries in the supported_gss_krb5_enctypes array for the
encryption types defined in RFC 8009. These new enctypes use the
SHA-256 and SHA-384 message digest algorithms (as defined in
FIPS-180) instead of the deprecated SHA-1 algorithm, and are thus
more secure.
Note that NIST has scheduled SHA-1 for deprecation:
https://www.nist.gov/news-events/news/2022/12/nist-retires-sha-1-cryptographic-algorithm
Thus these new encryption types are placed under a separate CONFIG
option to enable distributors to separately introduce support for
the AES-SHA2 enctypes and deprecate support for the current set of
AES-SHA1 encryption types as their user space allows.
As this implementation is still a "beta", the default is to not
build it automatically.
Tested-by: Scott Mayhew <smayhew@redhat.com>
Reviewed-by: Simo Sorce <simo@redhat.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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Cryptosystem profile enctypes all use cipher block chaining
with ciphertext steal (CBC-with-CTS). However enctypes that are
currently supported in the Linux kernel SunRPC implementation
use only the encrypt-&-MAC approach. The RFC 8009 enctypes use
encrypt-then-MAC, which performs encryption and checksumming in
a different order.
Refactor to make it possible to share the CBC with CTS encryption
and decryption mechanisms between e&M and etM enctypes.
Tested-by: Scott Mayhew <smayhew@redhat.com>
Reviewed-by: Simo Sorce <simo@redhat.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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The aes256-cts-hmac-sha384-192 enctype specifies the length of its
checksum and integrity subkeys as 192 bits, but the length of its
encryption subkey (Ke) as 256 bits. Add new fields to struct
gss_krb5_enctype that specify the key lengths individually, and
where needed, use the correct new field instead of ->keylength.
Tested-by: Scott Mayhew <smayhew@redhat.com>
Reviewed-by: Simo Sorce <simo@redhat.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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Although the Kerberos specs have always listed separate subkey
lengths, the Linux kernel's SunRPC GSS Kerberos enctype profiles
assume the base key and the derived keys have identical lengths.
The aes256-cts-hmac-sha384-192 enctype specifies the length of its
checksum and integrity subkeys as 192 bits, but the length of its
encryption subkey (Ke) as 256 bits.
To support that enctype, parametrize context_v2_alloc_cipher() so
that each of its call sites can pass in its desired key length. For
now it will be the same length as before (gk5e->keylength), but a
subsequent patch will change this.
Tested-by: Scott Mayhew <smayhew@redhat.com>
Reviewed-by: Simo Sorce <simo@redhat.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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De-duplicate some common code.
Tested-by: Scott Mayhew <smayhew@redhat.com>
Reviewed-by: Simo Sorce <simo@redhat.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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Each Kerberos enctype can have a different KDF. Refactor the key
derivation path to support different KDFs for the enctypes
introduced in subsequent patches.
In particular, expose the key derivation function in struct
gss_krb5_enctype instead of the enctype's preferred random-to-key
function. The latter is usually the identity function and is only
ever called during key derivation, so have each KDF call it
directly.
A couple of extra clean-ups:
- Deduplicate the set_cdata() helper
- Have ->derive_key return negative errnos, in accordance with usual
kernel coding conventions
This patch is a little bigger than I'd like, but these are all
mechanical changes and they are all to the same areas of code. No
behavior change is intended.
Tested-by: Scott Mayhew <smayhew@redhat.com>
Reviewed-by: Simo Sorce <simo@redhat.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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Clean up: there is now only one encrypt and only one decrypt method,
thus there is no longer a need for the v2-suffixed method names.
Tested-by: Scott Mayhew <smayhew@redhat.com>
Reviewed-by: Simo Sorce <simo@redhat.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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Clean up: ->encrypt is set to only one value. Replace the two
remaining call sites with direct calls to krb5_encrypt().
There have never been any call sites for the ->decrypt() method.
Tested-by: Scott Mayhew <smayhew@redhat.com>
Reviewed-by: Simo Sorce <simo@redhat.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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Because the DES block cipher has been deprecated by Internet
standard, highly secure configurations might require that DES
support be blacklisted or not installed. NFS Kerberos should still
be able to work correctly with only the AES-based enctypes in that
situation.
Also note that MIT Kerberos has begun a deprecation process for DES
encryption types. Their README for 1.19.3 states:
> Beginning with the krb5-1.19 release, a warning will be issued
> if initial credentials are acquired using the des3-cbc-sha1
> encryption type. In future releases, this encryption type will
> be disabled by default and eventually removed.
>
> Beginning with the krb5-1.18 release, single-DES encryption
> types have been removed.
Aside from the CONFIG option name change, there are two important
policy changes:
1. The 'insecure enctype' group is now disabled by default.
Distributors have to take action to enable support for deprecated
enctypes. Implementation of these enctypes will be removed in a
future kernel release.
2. des3-cbc-sha1 is now considered part of the 'insecure enctype'
group, having been deprecated by RFC 8429, and is thus disabled
by default
After this patch is applied, SunRPC support can be built with
Kerberos 5 support but without CRYPTO_DES enabled in the kernel.
And, when these enctypes are disabled, the Linux kernel's SunRPC
RPCSEC GSS implementation fully complies with BCP 179 / RFC 6649
and BCP 218 / RFC 8429.
Tested-by: Scott Mayhew <smayhew@redhat.com>
Reviewed-by: Simo Sorce <simo@redhat.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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Now that all consumers of the KRB5_SUPPORTED_ENCTYPES macro are
within the SunRPC layer, the macro can be replaced with something
private and more flexible.
Tested-by: Scott Mayhew <smayhew@redhat.com>
Reviewed-by: Simo Sorce <simo@redhat.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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I would like to replace the KRB5_SUPPORTED_ENCTYPES macro so that
there is finer granularity about what enctype support is built in
to the kernel and then advertised by it.
The /proc/fs/nfsd/supported_krb5_enctypes file is a legacy API
that advertises supported enctypes to rpc.svcgssd (I think?). It
simply prints the value of the KRB5_SUPPORTED_ENCTYPES macro, so it
will need to be replaced with something that can instead display
exactly which enctypes are configured and built into the SunRPC
layer.
Completely decommissioning such APIs is hard. Instead, add a file
that is managed by SunRPC's GSS Kerberos mechanism, which is
authoritative about enctype support status. A subsequent patch will
replace /proc/fs/nfsd/supported_krb5_enctypes with a symlink to this
new file.
Tested-by: Scott Mayhew <smayhew@redhat.com>
Reviewed-by: Simo Sorce <simo@redhat.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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Replace another switch on encryption type so that it does not have
to be modified when adding or removing support for an enctype.
Tested-by: Scott Mayhew <smayhew@redhat.com>
Reviewed-by: Simo Sorce <simo@redhat.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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Replace a number of switches on encryption type so that all of them don't
have to be modified when adding or removing support for an enctype.
Tested-by: Scott Mayhew <smayhew@redhat.com>
Reviewed-by: Simo Sorce <simo@redhat.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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There's no need to keep the integrity keys around if we instead
allocate and key a pair of ahashes and keep those. This not only
enables the subkeys to be destroyed immediately after deriving
them, but it makes the Kerberos integrity code path more efficient.
Tested-by: Scott Mayhew <smayhew@redhat.com>
Reviewed-by: Simo Sorce <simo@redhat.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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There's no need to keep the signing keys around if we instead allocate
and key an ahash and keep that. This not only enables the subkeys to
be destroyed immediately after deriving them, but it makes the
Kerberos signing code path more efficient.
Tested-by: Scott Mayhew <smayhew@redhat.com>
Reviewed-by: Simo Sorce <simo@redhat.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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The encryption subkeys are not used after the cipher transforms have
been allocated and keyed. There is no need to retain them in struct
krb5_ctx.
Tested-by: Scott Mayhew <smayhew@redhat.com>
Reviewed-by: Simo Sorce <simo@redhat.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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Hoist the name of the aux_cipher into struct gss_krb5_enctype to
prepare for obscuring the encryption keys just after they are
derived.
Tested-by: Scott Mayhew <smayhew@redhat.com>
Reviewed-by: Simo Sorce <simo@redhat.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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ctx->Ksess is never used after import has completed. Obscure it
immediately so it cannot be re-used or copied.
Tested-by: Scott Mayhew <smayhew@redhat.com>
Reviewed-by: Simo Sorce <simo@redhat.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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Other common Kerberos implementations use a fully random confounder
for encryption. The reason for this is explained in the new comment
added by this patch. The current get_random_bytes() implementation
does not exhaust system entropy.
Since confounder generation is part of Kerberos itself rather than
the GSS-API Kerberos mechanism, the function is renamed and moved.
Note that light top-down analysis shows that the SHA-1 transform
is by far the most CPU-intensive part of encryption. Thus we do not
expect this change to result in a significant performance impact.
However, eventually it might be necessary to generate an independent
stream of confounders for each Kerberos context to help improve I/O
parallelism.
Reviewed-by: Simo Sorce <simo@redhat.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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Now that arcfour-hmac is gone, the confounder length is again the
same as the cipher blocksize for every implemented enctype. The
gss_krb5_enctype::conflen field is no longer necessary.
Tested-by: Scott Mayhew <smayhew@redhat.com>
Reviewed-by: Simo Sorce <simo@redhat.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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It is not clear from documenting comments, specifications, or code
usage what value the gss_krb5_enctype.blocksize field is supposed
to store. The "encryption blocksize" depends only on the cipher
being used, so that value can be derived where it's needed instead
of stored as a constant.
RFC 3961 Section 5.2 says:
> cipher block size, c
> This is the block size of the block cipher underlying the
> encryption and decryption functions indicated above, used for key
> derivation and for the size of the message confounder and initial
> vector. (If a block cipher is not in use, some comparable
> parameter should be determined.) It must be at least 5 octets.
>
> This is not actually an independent parameter; rather, it is a
> property of the functions E and D. It is listed here to clarify
> the distinction between it and the message block size, m.
In the Linux kernel's implemenation of the SunRPC RPCSEC GSS
Kerberos 5 mechanism, the cipher block size, which is dependent on
the encryption and decryption transforms, is used only in
krb5_derive_key(), so it is straightforward to replace it.
Tested-by: Scott Mayhew <smayhew@redhat.com>
Reviewed-by: Simo Sorce <simo@redhat.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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Now that svcauth_gss_prepare_to_wrap() no longer computes the
location of RPC header fields in the response buffer,
svcauth_gss_accept() can save the location of the databody
rather than the location of the verifier.
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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To navigate around the space that svcauth_gss_accept() reserves
for the RPC payload body length and sequence number fields,
svcauth_gss_release() does a little dance with the reply's
accept_stat, moving the accept_stat value in the response buffer
down by two words.
Instead, let's have the ->accept() methods each set the proper
final location of the accept_stat to avoid having to move
things.
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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Now that each ->accept method has been converted, the
svcxdr_init_encode() calls can be hoisted back up into the generic
RPC server code.
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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