KEYS: trusted: allow use of TEE as backend without TCG_TPM support

With recent rework, trusted keys are no longer limited to TPM as trust
source. The Kconfig symbol is unchanged however leading to a few issues:

- TCG_TPM is required, even if only TEE is to be used
- Enabling TCG_TPM, but excluding it from available trusted sources
is not possible
- TEE=m && TRUSTED_KEYS=y will lead to TEE support being silently
dropped, which is not the best user experience

Remedy these issues by introducing two new boolean Kconfig symbols:
TRUSTED_KEYS_TPM and TRUSTED_KEYS_TEE with the appropriate
dependencies.

Any new code depending on the TPM trusted key backend in particular
or symbols exported by it will now need to explicitly state that it

depends on TRUSTED_KEYS && TRUSTED_KEYS_TPM

The latter to ensure the dependency is built and the former to ensure
it's reachable for module builds. There are no such users yet.

Reviewed-by: Sumit Garg <sumit.garg@linaro.org>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Reviewed-by: Pankaj Gupta <pankaj.gupta@nxp.com>
Tested-by: Pankaj Gupta <pankaj.gupta@nxp.com>
Tested-by: Andreas Rammhold <andreas@rammhold.de>
Tested-by: Tim Harvey <tharvey@gateworks.com>
Tested-by: Michael Walle <michael@walle.cc> # on ls1028a (non-E and E)
Tested-by: John Ernberg <john.ernberg@actia.se> # iMX8QXP
Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>

KEYS: encrypted: Instantiate key with user-provided decrypted data

For availability and performance reasons master keys often need to be
released outside of a Key Management Service (KMS) to clients. It
would be beneficial to provide a mechanism where the
wrapping/unwrapping of data encryption keys (DEKs) is not dependent
on a remote call at runtime yet security is not (or only minimally)
compromised. Master keys could be securely stored in the Kernel and
be used to wrap/unwrap keys from Userspace.

The encrypted.c class supports instantiation of encrypted keys with
either an already-encrypted key material, or by generating new key
material based on random numbers. This patch defines a new datablob
format: [<format>] <master-key name> <decrypted data length>
<decrypted data> that allows to inject and encrypt user-provided
decrypted data. The decrypted data must be hex-ascii encoded.

Signed-off-by: Yael Tzur <yaelt@google.com>
Reviewed-by: Mimi Zohar <zohar@linux.ibm.com>
Reviewed-by: Sumit Garg <sumit.garg@linaro.org>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>

security: DH - use KDF implementation from crypto API

The kernel crypto API provides the SP800-108 counter KDF implementation.
Thus, the separate implementation provided as part of the keys subsystem
can be replaced with calls to the KDF offered by the kernel crypto API.

The keys subsystem uses the counter KDF with a hash primitive. Thus,
it only uses the call to crypto_kdf108_ctr_generate.

Signed-off-by: Stephan Mueller <smueller@chronox.de>
Acked-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

security: keys: trusted: use ASN.1 TPM2 key format for the blobs

Modify the TPM2 key format blob output to export and import in the
ASN.1 form for TPM2 sealed object keys. For compatibility with prior
trusted keys, the importer will also accept two TPM2B quantities
representing the public and private parts of the key. However, the
export via keyctl pipe will only output the ASN.1 format.

The benefit of the ASN.1 format is that it's a standard and thus the
exported key can be used by userspace tools (openssl_tpm2_engine,
openconnect and tpm2-tss-engine). The format includes policy
specifications, thus it gets us out of having to construct policy
handles in userspace and the format includes the parent meaning you
don't have to keep passing it in each time.

This patch only implements basic handling for the ASN.1 format, so
keys with passwords but no policy.

Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
Tested-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>

watch_queue: Drop references to /dev/watch_queue

The merged API doesn't use a watch_queue device, but instead relies on
pipes, so let the documentation reflect that.

Fixes: f7e47677e39a ("watch_queue: Add a key/keyring notification facility")
Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Jarkko Sakkinen <jarkko@kernel.org>
Reviewed-by: Ben Boeckel <mathstuf@gmail.com>

security/keys: rewrite big_key crypto to use library interface

A while back, I noticed that the crypto and crypto API usage in big_keys
were entirely broken in multiple ways, so I rewrote it. Now, I'm
rewriting it again, but this time using the simpler ChaCha20Poly1305
library function. This makes the file considerably more simple; the
diffstat alone should justify this commit. It also should be faster,
since it no longer requires a mutex around the "aead api object" (nor
allocations), allowing us to encrypt multiple items in parallel. We also
benefit from being able to pass any type of pointer, so we can get rid
of the ridiculously complex custom page allocator that big_key really
doesn't need.

[DH: Change the select CRYPTO_LIB_CHACHA20POLY1305 to a depends on as
select doesn't propagate and the build can end up with an =y dependending
on some =m pieces.

The depends on CRYPTO also had to be removed otherwise the configurator
complains about a recursive dependency.]

Cc: Andy Lutomirski <luto@kernel.org>
Cc: Greg KH <gregkh@linuxfoundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: kernel-hardening@lists.openwall.com
Reviewed-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: David Howells <dhowells@redhat.com>

watch_queue: Add a key/keyring notification facility

Add a key/keyring change notification facility whereby notifications about
changes in key and keyring content and attributes can be received.

Firstly, an event queue needs to be created:

pipe2(fds, O_NOTIFICATION_PIPE);
ioctl(fds[1], IOC_WATCH_QUEUE_SET_SIZE, 256);

then a notification can be set up to report notifications via that queue:

struct watch_notification_filter filter = {
.nr_filters = 1,
.filters = {
[0] = {
.type = WATCH_TYPE_KEY_NOTIFY,
.subtype_filter[0] = UINT_MAX,
},
},
};
ioctl(fds[1], IOC_WATCH_QUEUE_SET_FILTER, &filter);
keyctl_watch_key(KEY_SPEC_SESSION_KEYRING, fds[1], 0x01);

After that, records will be placed into the queue when events occur in
which keys are changed in some way. Records are of the following format:

struct key_notification {
struct watch_notification watch;
__u32 key_id;
__u32 aux;
} *n;

Where:

n->watch.type will be WATCH_TYPE_KEY_NOTIFY.

n->watch.subtype will indicate the type of event, such as
NOTIFY_KEY_REVOKED.

n->watch.info & WATCH_INFO_LENGTH will indicate the length of the
record.

n->watch.info & WATCH_INFO_ID will be the second argument to
keyctl_watch_key(), shifted.

n->key will be the ID of the affected key.

n->aux will hold subtype-dependent information, such as the key
being linked into the keyring specified by n->key in the case of
NOTIFY_KEY_LINKED.

Note that it is permissible for event records to be of variable length -
or, at least, the length may be dependent on the subtype. Note also that
the queue can be shared between multiple notifications of various types.

Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: James Morris <jamorris@linux.microsoft.com>

KEYS: remove CONFIG_KEYS_COMPAT

KEYS_COMPAT now always takes the value of COMPAT && KEYS. But the
security/keys/ directory is only compiled if KEYS is enabled, so in
practice KEYS_COMPAT is the same as COMPAT. Therefore, remove the
unnecessary KEYS_COMPAT and just use COMPAT directly.

(Also remove an outdated comment from compat.c.)

Reviewed-by: James Morris <jamorris@linux.microsoft.com>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Tested-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>

keys: Cache result of request_key*() temporarily in task_struct

If a filesystem uses keys to hold authentication tokens, then it needs a
token for each VFS operation that might perform an authentication check -
either by passing it to the server, or using to perform a check based on
authentication data cached locally.

For open files this isn't a problem, since the key should be cached in the
file struct since it represents the subject performing operations on that
file descriptor.

During pathwalk, however, there isn't anywhere to cache the key, except
perhaps in the nameidata struct - but that isn't exposed to the
filesystems. Further, a pathwalk can incur a lot of operations, calling
one or more of the following, for instance:

->lookup()
->permission()
->d_revalidate()
->d_automount()
->get_acl()
->getxattr()

on each dentry/inode it encounters - and each one may need to call
request_key(). And then, at the end of pathwalk, it will call the actual
operation:

->mkdir()
->mknod()
->getattr()
->open()
...

which may need to go and get the token again.

However, it is very likely that all of the operations on a single
dentry/inode - and quite possibly a sequence of them - will all want to use
the same authentication token, which suggests that caching it would be a
good idea.

To this end:

(1) Make it so that a positive result of request_key() and co. that didn't
require upcalling to userspace is cached temporarily in task_struct.

(2) The cache is 1 deep, so a new result displaces the old one.

(3) The key is released by exit and by notify-resume.

(4) The cache is cleared in a newly forked process.

Signed-off-by: David Howells <dhowells@redhat.com>

treewide: Add SPDX license identifier - Makefile/Kconfig

Add SPDX license identifiers to all Make/Kconfig files which:

- Have no license information of any form

These files fall under the project license, GPL v2 only. The resulting SPDX
license identifier is:

GPL-2.0-only

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

security/keys: BIG_KEY requires CONFIG_CRYPTO

The recent rework introduced a possible randconfig build failure
when CONFIG_CRYPTO configured to only allow modules:

security/keys/big_key.o: In function `big_key_crypt':
big_key.c:(.text+0x29f): undefined reference to `crypto_aead_setkey'
security/keys/big_key.o: In function `big_key_init':
big_key.c:(.init.text+0x1a): undefined reference to `crypto_alloc_aead'
big_key.c:(.init.text+0x45): undefined reference to `crypto_aead_setauthsize'
big_key.c:(.init.text+0x77): undefined reference to `crypto_destroy_tfm'
crypto/gcm.o: In function `gcm_hash_crypt_remain_continue':
gcm.c:(.text+0x167): undefined reference to `crypto_ahash_finup'
crypto/gcm.o: In function `crypto_gcm_exit_tfm':
gcm.c:(.text+0x847): undefined reference to `crypto_destroy_tfm'

When we 'select CRYPTO' like the other users, we always get a
configuration that builds.

Fixes: 428490e38b2e ("security/keys: rewrite all of big_key crypto")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: David Howells <dhowells@redhat.com>

security/keys: rewrite all of big_key crypto

This started out as just replacing the use of crypto/rng with
get_random_bytes_wait, so that we wouldn't use bad randomness at boot
time. But, upon looking further, it appears that there were even deeper
underlying cryptographic problems, and that this seems to have been
committed with very little crypto review. So, I rewrote the whole thing,
trying to keep to the conventions introduced by the previous author, to
fix these cryptographic flaws.

It makes no sense to seed crypto/rng at boot time and then keep
using it like this, when in fact there's already get_random_bytes_wait,
which can ensure there's enough entropy and be a much more standard way
of generating keys. Since this sensitive material is being stored
untrusted, using ECB and no authentication is simply not okay at all. I
find it surprising and a bit horrifying that this code even made it past
basic crypto review, which perhaps points to some larger issues. This
patch moves from using AES-ECB to using AES-GCM. Since keys are uniquely
generated each time, we can set the nonce to zero. There was also a race
condition in which the same key would be reused at the same time in
different threads. A mutex fixes this issue now.

So, to summarize, this commit fixes the following vulnerabilities:

* Low entropy key generation, allowing an attacker to potentially
guess or predict keys.
* Unauthenticated encryption, allowing an attacker to modify the
cipher text in particular ways in order to manipulate the plaintext,
which is is even more frightening considering the next point.
* Use of ECB mode, allowing an attacker to trivially swap blocks or
compare identical plaintext blocks.
* Key re-use.
* Faulty memory zeroing.

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Reviewed-by: Eric Biggers <ebiggers3@gmail.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Kirill Marinushkin <k.marinushkin@gmail.com>
Cc: security@kernel.org
Cc: stable@vger.kernel.org

KEYS: Convert KEYCTL_DH_COMPUTE to use the crypto KPP API

The initial Diffie-Hellman computation made direct use of the MPI
library because the crypto module did not support DH at the time. Now
that KPP is implemented, KEYCTL_DH_COMPUTE should use it to get rid of
duplicate code and leverage possible hardware acceleration.

This fixes an issue whereby the input to the KDF computation would
include additional uninitialized memory when the result of the
Diffie-Hellman computation was shorter than the input prime number.

Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: James Morris <james.l.morris@oracle.com>

security/keys: add CONFIG_KEYS_COMPAT to Kconfig

CONFIG_KEYS_COMPAT is defined in arch-specific Kconfigs and is missing for
several 64-bit architectures : mips, parisc, tile.

At the moment and for those architectures, calling in 32-bit userspace the
keyctl syscall would return an ENOSYS error.

This patch moves the CONFIG_KEYS_COMPAT option to security/keys/Kconfig, to
make sure the compatibility wrapper is registered by default for any 64-bit
architecture as long as it is configured with CONFIG_COMPAT.

[DH: Modified to remove arm64 compat enablement also as requested by Eric
Biggers]

Signed-off-by: Bilal Amarni <bilal.amarni@gmail.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
cc: Eric Biggers <ebiggers3@gmail.com>
Signed-off-by: James Morris <james.l.morris@oracle.com>

keys: select CONFIG_CRYPTO when selecting DH / KDF

Select CONFIG_CRYPTO in addition to CONFIG_HASH to ensure that
also CONFIG_HASH2 is selected. Both are needed for the shash
cipher support required for the KDF operation.

Signed-off-by: Stephan Mueller <smueller@chronox.de>
Signed-off-by: David Howells <dhowells@redhat.com>

KEYS: add SP800-56A KDF support for DH

SP800-56A defines the use of DH with key derivation function based on a
counter. The input to the KDF is defined as (DH shared secret || other
information). The value for the "other information" is to be provided by
the caller.

The KDF is implemented using the hash support from the kernel crypto API.
The implementation uses the symmetric hash support as the input to the
hash operation is usually very small. The caller is allowed to specify
the hash name that he wants to use to derive the key material allowing
the use of all supported hashes provided with the kernel crypto API.

As the KDF implements the proper truncation of the DH shared secret to
the requested size, this patch fills the caller buffer up to its size.

The patch is tested with a new test added to the keyutils user space
code which uses a CAVS test vector testing the compliance with
SP800-56A.

Signed-off-by: Stephan Mueller <smueller@chronox.de>
Signed-off-by: David Howells <dhowells@redhat.com>

security/keys: make BIG_KEYS dependent on stdrng.

Since BIG_KEYS can't be compiled as module it requires one of the "stdrng"
providers to be compiled into kernel. Otherwise big_key_crypto_init() fails
on crypto_alloc_rng step and next dereference of big_key_skcipher (e.g. in
big_key_preparse()) results in a NULL pointer dereference.

Fixes: 13100a72f40f5748a04017e0ab3df4cf27c809ef ('Security: Keys: Big keys stored encrypted')
Signed-off-by: Artem Savkov <asavkov@redhat.com>
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Stephan Mueller <smueller@chronox.de>
cc: Kirill Marinushkin <k.marinushkin@gmail.com>
cc: stable@vger.kernel.org
Signed-off-by: James Morris <james.l.morris@oracle.com>

KEYS: Add KEYCTL_DH_COMPUTE command

This adds userspace access to Diffie-Hellman computations through a
new keyctl() syscall command to calculate shared secrets or public
keys using input parameters stored in the keyring.

Input key ids are provided in a struct due to the current 5-arg limit
for the keyctl syscall. Only user keys are supported in order to avoid
exposing the content of logon or encrypted keys.

The output is written to the provided buffer, based on the assumption
that the values are only needed in userspace.

Future support for other types of key derivation would involve a new
command, like KEYCTL_ECDH_COMPUTE.

Once Diffie-Hellman support is included in the crypto API, this code
can be converted to use the crypto API to take advantage of possible
hardware acceleration and reduce redundant code.

Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: David Howells <dhowells@redhat.com>

Security: Keys: Big keys stored encrypted

Solved TODO task: big keys saved to shmem file are now stored encrypted.
The encryption key is randomly generated and saved to payload[big_key_data].

Signed-off-by: Kirill Marinushkin <k.marinushkin@gmail.com>
Signed-off-by: David Howells <dhowells@redhat.com>

keys, trusted: select hash algorithm for TPM2 chips

Added 'hash=' option for selecting the hash algorithm for add_key()
syscall and documentation for it.

Added entry for sm3-256 to the following tables in order to support
TPM_ALG_SM3_256:

* hash_algo_name
* hash_digest_size

Includes support for the following hash algorithms:

* sha1
* sha256
* sha384
* sha512
* sm3-256

Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Tested-by: Colin Ian King <colin.king@canonical.com>
Reviewed-by: James Morris <james.l.morris@oracle.com>
Reviewed-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Acked-by: Peter Huewe <peterhuewe@gmx.de>

KEYS: Make /proc/keys unconditional if CONFIG_KEYS=y

Now that /proc/keys is used by libkeyutils to look up a key by type and
description, we should make it unconditional and remove
CONFIG_DEBUG_PROC_KEYS.

Reported-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: David Howells <dhowells@redhat.com>
Tested-by: Jiri Kosina <jkosina@suse.cz>

KEYS: Make BIG_KEYS boolean

Having the big_keys functionality as a module is very marginally useful.
The userspace code that would use this functionality will get odd error
messages from the keys layer if the module isn't loaded. The code itself
is fairly small, so just have this as a boolean option and not a tristate.

Signed-off-by: Josh Boyer <jwboyer@fedoraproject.org>
Signed-off-by: David Howells <dhowells@redhat.com>

KEYS: Add per-user_namespace registers for persistent per-UID kerberos caches

Add support for per-user_namespace registers of persistent per-UID kerberos
caches held within the kernel.

This allows the kerberos cache to be retained beyond the life of all a user's
processes so that the user's cron jobs can work.

The kerberos cache is envisioned as a keyring/key tree looking something like:

struct user_namespace
\___ .krb_cache keyring - The register
\___ _krb.0 keyring - Root's Kerberos cache
\___ _krb.5000 keyring - User 5000's Kerberos cache
\___ _krb.5001 keyring - User 5001's Kerberos cache
\___ tkt785 big_key - A ccache blob
\___ tkt12345 big_key - Another ccache blob

Or possibly:

struct user_namespace
\___ .krb_cache keyring - The register
\___ _krb.0 keyring - Root's Kerberos cache
\___ _krb.5000 keyring - User 5000's Kerberos cache
\___ _krb.5001 keyring - User 5001's Kerberos cache
\___ tkt785 keyring - A ccache
\___ krbtgt/REDHAT.COM@REDHAT.COM big_key
\___ http/REDHAT.COM@REDHAT.COM user
\___ afs/REDHAT.COM@REDHAT.COM user
\___ nfs/REDHAT.COM@REDHAT.COM user
\___ krbtgt/KERNEL.ORG@KERNEL.ORG big_key
\___ http/KERNEL.ORG@KERNEL.ORG big_key

What goes into a particular Kerberos cache is entirely up to userspace. Kernel
support is limited to giving you the Kerberos cache keyring that you want.

The user asks for their Kerberos cache by:

krb_cache = keyctl_get_krbcache(uid, dest_keyring);

The uid is -1 or the user's own UID for the user's own cache or the uid of some
other user's cache (requires CAP_SETUID). This permits rpc.gssd or whatever to
mess with the cache.

The cache returned is a keyring named "_krb.<uid>" that the possessor can read,
search, clear, invalidate, unlink from and add links to. Active LSMs get a
chance to rule on whether the caller is permitted to make a link.

Each uid's cache keyring is created when it first accessed and is given a
timeout that is extended each time this function is called so that the keyring
goes away after a while. The timeout is configurable by sysctl but defaults to
three days.

Each user_namespace struct gets a lazily-created keyring that serves as the
register. The cache keyrings are added to it. This means that standard key
search and garbage collection facilities are available.

The user_namespace struct's register goes away when it does and anything left
in it is then automatically gc'd.

Signed-off-by: David Howells <dhowells@redhat.com>
Tested-by: Simo Sorce <simo@redhat.com>
cc: Serge E. Hallyn <serge.hallyn@ubuntu.com>
cc: Eric W. Biederman <ebiederm@xmission.com>

KEYS: Implement a big key type that can save to tmpfs

Implement a big key type that can save its contents to tmpfs and thus
swapspace when memory is tight. This is useful for Kerberos ticket caches.

Signed-off-by: David Howells <dhowells@redhat.com>
Tested-by: Simo Sorce <simo@redhat.com>

KEYS: Expand the capacity of a keyring

Expand the capacity of a keyring to be able to hold a lot more keys by using
the previously added associative array implementation. Currently the maximum
capacity is:

(PAGE_SIZE - sizeof(header)) / sizeof(struct key *)

which, on a 64-bit system, is a little more 500. However, since this is being
used for the NFS uid mapper, we need more than that. The new implementation
gives us effectively unlimited capacity.

With some alterations, the keyutils testsuite runs successfully to completion
after this patch is applied. The alterations are because (a) keyrings that
are simply added to no longer appear ordered and (b) some of the errors have
changed a bit.

Signed-off-by: David Howells <dhowells@redhat.com>

KEYS: Move the key config into security/keys/Kconfig

Move the key config into security/keys/Kconfig as there are going to be a lot
of key-related options.

Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Mimi Zohar <zohar@us.ibm.com>