apparmor: switch SECURITY_APPARMOR_HASH from sha1 to sha256

sha1 is insecure and has colisions, thus it is not useful for even
lightweight policy hash checks. Switch to sha256, which on modern
hardware is fast enough.

Separately as per NIST Policy on Hash Functions, sha1 usage must be
withdrawn by 2030. This config option currently is one of many that
holds up sha1 usage.

Signed-off-by: Dimitri John Ledkov <dimitri.ledkov@canonical.com>
Signed-off-by: John Johansen <john.johansen@canonical.com>

apparmor: Return directly after a failed kzalloc() in two functions

1. Return directly after a call of the function “kzalloc” failed
at the beginning in these function implementations.

2. Omit extra initialisations (for a few local variables)
which became unnecessary with this refactoring.

This issue was detected by using the Coccinelle software.

Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
Signed-off-by: John Johansen <john.johansen@canonical.com>

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 441

Based on 1 normalized pattern(s):

this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license as published by
the free software foundation version 2 of the license

extracted by the scancode license scanner the SPDX license identifier

GPL-2.0-only

has been chosen to replace the boilerplate/reference in 315 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Allison Randal <allison@lohutok.net>
Reviewed-by: Armijn Hemel <armijn@tjaldur.nl>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190531190115.503150771@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

crypto: shash - remove shash_desc::flags

The flags field in 'struct shash_desc' never actually does anything.
The only ostensibly supported flag is CRYPTO_TFM_REQ_MAY_SLEEP.
However, no shash algorithm ever sleeps, making this flag a no-op.

With this being the case, inevitably some users who can't sleep wrongly
pass MAY_SLEEP. These would all need to be fixed if any shash algorithm
actually started sleeping. For example, the shash_ahash_*() functions,
which wrap a shash algorithm with the ahash API, pass through MAY_SLEEP
from the ahash API to the shash API. However, the shash functions are
called under kmap_atomic(), so actually they're assumed to never sleep.

Even if it turns out that some users do need preemption points while
hashing large buffers, we could easily provide a helper function
crypto_shash_update_large() which divides the data into smaller chunks
and calls crypto_shash_update() and cond_resched() for each chunk. It's
not necessary to have a flag in 'struct shash_desc', nor is it necessary
to make individual shash algorithms aware of this at all.

Therefore, remove shash_desc::flags, and document that the
crypto_shash_*() functions can be called from any context.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

crypto: drop mask=CRYPTO_ALG_ASYNC from 'shash' tfm allocations

'shash' algorithms are always synchronous, so passing CRYPTO_ALG_ASYNC
in the mask to crypto_alloc_shash() has no effect. Many users therefore
already don't pass it, but some still do. This inconsistency can cause
confusion, especially since the way the 'mask' argument works is
somewhat counterintuitive.

Thus, just remove the unneeded CRYPTO_ALG_ASYNC flags.

This patch shouldn't change any actual behavior.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

apparmor: use SHASH_DESC_ON_STACK

When building the kernel with clang, the compiler fails to build
security/apparmor/crypto.c with the following error:

security/apparmor/crypto.c:36:8: error: fields must have a constant
size: 'variable length array in structure' extension will never be
supported
char ctx[crypto_shash_descsize(apparmor_tfm)];
^

Since commit a0a77af14117 ("crypto: LLVMLinux: Add macro to remove use
of VLAIS in crypto code"), include/crypto/hash.h defines
SHASH_DESC_ON_STACK to work around this issue. Use it in aa_calc_hash()
and aa_calc_profile_hash().

Signed-off-by: Nicolas Iooss <nicolas.iooss_linux@m4x.org>
Signed-off-by: John Johansen <john.johansen@canonical.com>
Signed-off-by: James Morris <james.l.morris@oracle.com>

apparmor: allow introspecting the loaded policy pre internal transform

Store loaded policy and allow introspecting it through apparmorfs. This
has several uses from debugging, policy validation, and policy checkpoint
and restore for containers.

Signed-off-by: John Johansen <john.johansen@canonical.com>

apparmor: fix SECURITY_APPARMOR_HASH_DEFAULT parameter handling

The newly added Kconfig option could never work and just causes a build error
when disabled:

security/apparmor/lsm.c:675:25: error: 'CONFIG_SECURITY_APPARMOR_HASH_DEFAULT' undeclared here (not in a function)
bool aa_g_hash_policy = CONFIG_SECURITY_APPARMOR_HASH_DEFAULT;

The problem is that the macro undefined in this case, and we need to use the IS_ENABLED()
helper to turn it into a boolean constant.

Another minor problem with the original patch is that the option is even offered
in sysfs when SECURITY_APPARMOR_HASH is not enabled, so this also hides the option
in that case.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Fixes: 6059f71f1e94 ("apparmor: add parameter to control whether policy hashing is used")
Signed-off-by: John Johansen <john.johansen@canonical.com>
Signed-off-by: James Morris <james.l.morris@oracle.com>

apparmor: Use shash crypto API interface for profile hashes

Use the shash interface, rather than the hash interface, when hashing
AppArmor profiles. The shash interface does not use scatterlists and it
is a better fit for what AppArmor needs.

This fixes a kernel paging BUG when aa_calc_profile_hash() is passed a
buffer from vmalloc(). The hash interface requires callers to handle
vmalloc() buffers differently than what AppArmor was doing. Due to
vmalloc() memory not being physically contiguous, each individual page
behind the buffer must be assigned to a scatterlist with sg_set_page()
and then the scatterlist passed to crypto_hash_update().

The shash interface does not have that limitation and allows vmalloc()
and kmalloc() buffers to be handled in the same manner.

BugLink: https://launchpad.net/bugs/1216294/
BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=62261

Signed-off-by: Tyler Hicks <tyhicks@canonical.com>
Acked-by: Seth Arnold <seth.arnold@canonical.com>
Signed-off-by: John Johansen <john.johansen@canonical.com>
Signed-off-by: James Morris <james.l.morris@oracle.com>

apparmor: add the ability to report a sha1 hash of loaded policy

Provide userspace the ability to introspect a sha1 hash value for each
profile currently loaded.

Signed-off-by: John Johansen <john.johansen@canonical.com>
Acked-by: Seth Arnold <seth.arnold@canonical.com>