linux.git/crypto/ecdh.c, branch v5.11

crypto: ecdh - avoid buffer overflow in ecdh_set_secret()

2021-01-02T21:35:35+00:00

Pavel reports that commit 17858b140bf4 ("crypto: ecdh - avoid unaligned
accesses in ecdh_set_secret()") fixes one problem but introduces another:
the unconditional memcpy() introduced by that commit may overflow the
target buffer if the source data is invalid, which could be the result of
intentional tampering.

So check params.key_size explicitly against the size of the target buffer
before validating the key further.

Fixes: 17858b140bf4 ("crypto: ecdh - avoid unaligned accesses in ecdh_set_secret()")
Reported-by: Pavel Machek 
Cc: 
Signed-off-by: Ard Biesheuvel 
Signed-off-by: Herbert Xu

crypto: ecdh - avoid unaligned accesses in ecdh_set_secret()

2020-12-04T07:13:13+00:00

ecdh_set_secret() casts a void* pointer to a const u64* in order to
feed it into ecc_is_key_valid(). This is not generally permitted by
the C standard, and leads to actual misalignment faults on ARMv6
cores. In some cases, these are fixed up in software, but this still
leads to performance hits that are entirely avoidable.

So let's copy the key into the ctx buffer first, which we will do
anyway in the common case, and which guarantees correct alignment.

Cc: 
Signed-off-by: Ard Biesheuvel 
Signed-off-by: Herbert Xu

mm, treewide: rename kzfree() to kfree_sensitive()

2020-08-07T18:33:22+00:00

As said by Linus:

  A symmetric naming is only helpful if it implies symmetries in use.
  Otherwise it's actively misleading.

  In "kzalloc()", the z is meaningful and an important part of what the
  caller wants.

  In "kzfree()", the z is actively detrimental, because maybe in the
  future we really _might_ want to use that "memfill(0xdeadbeef)" or
  something. The "zero" part of the interface isn't even _relevant_.

The main reason that kzfree() exists is to clear sensitive information
that should not be leaked to other future users of the same memory
objects.

Rename kzfree() to kfree_sensitive() to follow the example of the recently
added kvfree_sensitive() and make the intention of the API more explicit.
In addition, memzero_explicit() is used to clear the memory to make sure
that it won't get optimized away by the compiler.

The renaming is done by using the command sequence:

  git grep -w --name-only kzfree |\
  xargs sed -i 's/kzfree/kfree_sensitive/'

followed by some editing of the kfree_sensitive() kerneldoc and adding
a kzfree backward compatibility macro in slab.h.

[akpm@linux-foundation.org: fs/crypto/inline_crypt.c needs linux/slab.h]
[akpm@linux-foundation.org: fix fs/crypto/inline_crypt.c some more]

Suggested-by: Joe Perches 
Signed-off-by: Waiman Long 
Signed-off-by: Andrew Morton 
Acked-by: David Howells 
Acked-by: Michal Hocko 
Acked-by: Johannes Weiner 
Cc: Jarkko Sakkinen 
Cc: James Morris 
Cc: "Serge E. Hallyn" 
Cc: Joe Perches 
Cc: Matthew Wilcox 
Cc: David Rientjes 
Cc: Dan Carpenter 
Cc: "Jason A . Donenfeld" 
Link: http://lkml.kernel.org/r/20200616154311.12314-3-longman@redhat.com
Signed-off-by: Linus Torvalds

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152

2019-05-30T18:26:32+00:00

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 either version 2 of the license or at
  your option any later version

extracted by the scancode license scanner the SPDX license identifier

  GPL-2.0-or-later

has been chosen to replace the boilerplate/reference in 3029 file(s).

Signed-off-by: Thomas Gleixner 
Reviewed-by: Allison Randal 
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190527070032.746973796@linutronix.de
Signed-off-by: Greg Kroah-Hartman

crypto: run initcalls for generic implementations earlier

2019-04-18T14:15:03+00:00

Use subsys_initcall for registration of all templates and generic
algorithm implementations, rather than module_init.  Then change
cryptomgr to use arch_initcall, to place it before the subsys_initcalls.

This is needed so that when both a generic and optimized implementation
of an algorithm are built into the kernel (not loadable modules), the
generic implementation is registered before the optimized one.
Otherwise, the self-tests for the optimized implementation are unable to
allocate the generic implementation for the new comparison fuzz tests.

Note that on arm, a side effect of this change is that self-tests for
generic implementations may run before the unaligned access handler has
been installed.  So, unaligned accesses will crash the kernel.  This is
arguably a good thing as it makes it easier to detect that type of bug.

Signed-off-by: Eric Biggers 
Signed-off-by: Herbert Xu

crypto: ecc - Actually remove stack VLA usage

2018-04-20T16:58:29+00:00

On the quest to remove all VLAs from the kernel[1], this avoids VLAs
by just using the maximum allocation size (4 bytes) for stack arrays.
All the VLAs in ecc were either 3 or 4 bytes (or a multiple), so just
make it 4 bytes all the time. Initialization routines are adjusted to
check that ndigits does not end up larger than the arrays.

This includes a removal of the earlier attempt at this fix from
commit a963834b4742 ("crypto/ecc: Remove stack VLA usage")

[1] https://lkml.org/lkml/2018/3/7/621

Signed-off-by: Kees Cook 
Signed-off-by: Herbert Xu

crypto: ecdh - fix to allow multi segment scatterlists

2018-03-09T14:45:49+00:00

Apparently the ecdh use case was in bluetooth which always has single
element scatterlists, so the ecdh module was hard coded to expect
them.  Now we're using this in TPM, we need multi-element
scatterlists, so remove this limitation.

Signed-off-by: James Bottomley 
Signed-off-by: Herbert Xu

crypto: ecdh - remove empty exit()

2017-11-06T06:45:04+00:00

Pointer members of an object with static storage duration, if not
explicitly initialized, will be initialized to a NULL pointer. The crypto
API checks if this pointer is not NULL before using it, we are safe to
remove the function.

Signed-off-by: Tudor Ambarus 
Signed-off-by: Herbert Xu

crypto: ecdh - fix concurrency on shared secret and pubkey

2017-08-03T05:47:22+00:00

ecdh_ctx contained static allocated data for the shared secret
and public key.

The shared secret and the public key were doomed to concurrency
issues because they could be shared by multiple crypto requests.

The concurrency is fixed by replacing per-tfm shared secret and
public key with per-request dynamically allocated shared secret
and public key.

Signed-off-by: Tudor Ambarus 
Signed-off-by: Herbert Xu

crypto: ecdh - add privkey generation support

2017-06-10T04:04:35+00:00

Add support for generating ecc private keys.

Generation of ecc private keys is helpful in a user-space to kernel
ecdh offload because the keys are not revealed to user-space. Private
key generation is also helpful to implement forward secrecy.

If the user provides a NULL ecc private key, the kernel will generate it
and further use it for ecdh.

Move ecdh's object files below drbg's. drbg must be present in the kernel
at the time of calling.

Signed-off-by: Tudor Ambarus 
Reviewed-by: Stephan Müller 
Signed-off-by: Herbert Xu