scatterwalk_done() is only meant to be called after a nonzero number of
bytes have been processed, since scatterwalk_pagedone() will flush the
dcache of the *previous* page. But in the error case of
skcipher_walk_done(), e.g. if the input wasn't an integer number of
blocks, scatterwalk_done() was actually called after advancing 0 bytes.
This caused a crash ("BUG: unable to handle kernel paging request")
during '!PageSlab(page)' on architectures like arm and arm64 that define
ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE, provided that the input was
page-aligned as in that case walk->offset == 0.
Fix it by reorganizing skcipher_walk_done() to skip the
scatterwalk_advance() and scatterwalk_done() if an error has occurred.
This bug was found by syzkaller fuzzing.
Reproducer, assuming ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE:
#include <linux/if_alg.h>
#include <sys/socket.h>
#include <unistd.h>
int main()
{
struct sockaddr_alg addr = {
.salg_type = "skcipher",
.salg_name = "cbc(aes-generic)",
};
char buffer[4096] __attribute__((aligned(4096))) = { 0 };
int fd;
fd = socket(AF_ALG, SOCK_SEQPACKET, 0);
bind(fd, (void *)&addr, sizeof(addr));
setsockopt(fd, SOL_ALG, ALG_SET_KEY, buffer, 16);
fd = accept(fd, NULL, NULL);
write(fd, buffer, 15);
read(fd, buffer, 15);
}
Reported-by: Liu Chao <liuchao741@huawei.com>
Fixes: b286d8b1a6 ("crypto: skcipher - Add skcipher walk interface")
Cc: <stable@vger.kernel.org> # v4.10+
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Setting 'walk->nbytes = walk->total' in skcipher_walk_first() doesn't
make sense because actually walk->nbytes needs to be set to the length
of the first step in the walk, which may be less than walk->total. This
is done by skcipher_walk_next() which is called immediately afterwards.
Also walk->nbytes was already set to 0 in skcipher_walk_skcipher(),
which is a better default value in case it's forgotten to be set later.
Therefore, remove the unnecessary assignment to walk->nbytes.
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
The ALIGN() macro needs to be passed the alignment, not the alignmask
(which is the alignment minus 1).
Fixes: b286d8b1a6 ("crypto: skcipher - Add skcipher walk interface")
Cc: <stable@vger.kernel.org> # v4.10+
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
The function skcipher_walk_next declared as static and marked as
EXPORT_SYMBOL_GPL. It's a bit confusing for internal function to be
exported. The area of visibility for such function is its .c file
and all other modules. Other *.c files of the same module can't use it,
despite all other modules can. Relying on the fact that this is the
internal function and it's not a crucial part of the API, the patch
just removes the EXPORT_SYMBOL_GPL marking of skcipher_walk_next.
Found by Linux Driver Verification project (linuxtesting.org).
Signed-off-by: Denis Efremov <efremov@linux.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Similar to what was done for the hash API, update the skcipher API to
track whether each transform has been keyed, and reject
encryption/decryption if a key is needed but one hasn't been set.
This isn't as important as the equivalent fix for the hash API because
symmetric ciphers almost always require a key (the "null cipher" is the
only exception), so are unlikely to be used without one. Still,
tracking the key will prevent accidental unkeyed use. algif_skcipher
also had to track the key anyway, so the new flag replaces that and
simplifies the algif_skcipher implementation.
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
All the ChaCha20 algorithms as well as the ARM bit-sliced AES-XTS
algorithms call skcipher_walk_virt(), then access the IV (walk.iv)
before checking whether any bytes need to be processed (walk.nbytes).
But if the input is empty, then skcipher_walk_virt() doesn't set the IV,
and the algorithms crash trying to use the uninitialized IV pointer.
Fix it by setting the IV earlier in skcipher_walk_virt(). Also fix it
for the AEAD walk functions.
This isn't a perfect solution because we can't actually align the IV to
->cra_alignmask unless there are bytes to process, for one because the
temporary buffer for the aligned IV is freed by skcipher_walk_done(),
which is only called when there are bytes to process. Thus, algorithms
that require aligned IVs will still need to avoid accessing the IV when
walk.nbytes == 0. Still, many algorithms/architectures are fine with
IVs having any alignment, and even for those that aren't, a misaligned
pointer bug is much less severe than an uninitialized pointer bug.
This change also matches the behavior of the older blkcipher_walk API.
Fixes: 0cabf2af6f ("crypto: skcipher - Fix crash on zero-length input")
Reported-by: syzbot <syzkaller@googlegroups.com>
Cc: <stable@vger.kernel.org> # v4.14+
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
The skcipher_walk_aead_common function calls scatterwalk_copychunks on
the input and output walks to skip the associated data. If the AD end
at an SG list entry boundary, then after these calls the walks will
still be pointing to the end of the skipped region.
These offsets are later checked for alignment in skcipher_walk_next,
so the skcipher_walk may detect the alignment incorrectly.
This patch fixes it by calling scatterwalk_done after the copychunks
calls to ensure that the offsets refer to the right SG list entry.
Fixes: b286d8b1a6 ("crypto: skcipher - Add skcipher walk interface")
Cc: <stable@vger.kernel.org>
Signed-off-by: Ondrej Mosnacek <omosnacek@gmail.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
The skcipher walk interface doesn't handle zero-length input
properly as the old blkcipher walk interface did. This is due
to the fact that the length check is done too late.
This patch moves the length check forward so that it does the
right thing.
Fixes: b286d8b1a6 ("crypto: skcipher - Add skcipher walk...")
Cc: <stable@vger.kernel.org>
Reported-by: Stephan Müller <smueller@chronox.de>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
The API setkey checks for key sizes and alignment went AWOL during the
skcipher conversion. This patch restores them.
Cc: <stable@vger.kernel.org>
Fixes: 4e6c3df4d7 ("crypto: skcipher - Add low-level skcipher...")
Reported-by: Baozeng <sploving1@gmail.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Continuing from this commit: 52f5684c8e
("kernel: use macros from compiler.h instead of __attribute__((...))")
I submitted 4 total patches. They are part of task I've taken up to
increase compiler portability in the kernel. I've cleaned up the
subsystems under /kernel /mm /block and /security, this patch targets
/crypto.
There is <linux/compiler.h> which provides macros for various gcc specific
constructs. Eg: __weak for __attribute__((weak)). I've cleaned all
instances of gcc specific attributes with the right macros for the crypto
subsystem.
I had to make one additional change into compiler-gcc.h for the case when
one wants to use this: __attribute__((aligned) and not specify an alignment
factor. From the gcc docs, this will result in the largest alignment for
that data type on the target machine so I've named the macro
__aligned_largest. Please advise if another name is more appropriate.
Signed-off-by: Gideon Israel Dsouza <gidisrael@gmail.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
In some cases, SIMD algorithms can only perform optimally when
allowed to operate on multiple input blocks in parallel. This is
especially true for bit slicing algorithms, which typically take
the same amount of time processing a single block or 8 blocks in
parallel. However, other SIMD algorithms may benefit as well from
bigger strides.
So add a walksize attribute to the skcipher algorithm definition, and
wire it up to the skcipher walk API. To avoid confusion between the
skcipher and AEAD attributes, rename the skcipher_walk chunksize
attribute to 'stride', and set it from the walksize (in the skcipher
case) or from the chunksize (in the AEAD case).
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
The new skcipher walk API may crash in the following way. (Interestingly,
the tcrypt boot time tests seem unaffected, while an explicit test using
the module triggers it)
Unable to handle kernel NULL pointer dereference at virtual address 00000000
...
[<ffff000008431d84>] __memcpy+0x84/0x180
[<ffff0000083ec0d0>] skcipher_walk_done+0x328/0x340
[<ffff0000080c5c04>] ctr_encrypt+0x84/0x100
[<ffff000008406d60>] simd_skcipher_encrypt+0x88/0x98
[<ffff0000083fa05c>] crypto_rfc3686_crypt+0x8c/0x98
[<ffff0000009b0900>] test_skcipher_speed+0x518/0x820 [tcrypt]
[<ffff0000009b31c0>] do_test+0x1408/0x3b70 [tcrypt]
[<ffff0000009bd050>] tcrypt_mod_init+0x50/0x1000 [tcrypt]
[<ffff0000080838f4>] do_one_initcall+0x44/0x138
[<ffff0000081aee60>] do_init_module+0x68/0x1e0
[<ffff0000081524d0>] load_module+0x1fd0/0x2458
[<ffff000008152c38>] SyS_finit_module+0xe0/0xf0
[<ffff0000080836f0>] el0_svc_naked+0x24/0x28
This is due to the fact that skcipher_done_slow() may be entered with
walk->buffer unset. Since skcipher_walk_done() already deals with the
case where walk->buffer == walk->page, it appears to be the intention
that walk->buffer point to walk->page after skcipher_next_slow(), so
ensure that is the case.
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
The AEAD decrypt interface includes the authentication tag in
req->cryptlen. Therefore we need to exlucde that when doing
a walk over it.
This patch adds separate walker functions for AEAD encryption
and decryption.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
The new skcipher_walk_aead() may crash in the following way due to
the walk flag SKCIPHER_WALK_PHYS not being cleared at the start of the
walk:
Unable to handle kernel NULL pointer dereference at virtual address 00000001
[..]
Internal error: Oops: 96000044 [#1] PREEMPT SMP
[..]
PC is at skcipher_walk_next+0x208/0x450
LR is at skcipher_walk_next+0x1e4/0x450
pc : [<ffff2b93b7104e20>] lr : [<ffff2b93b7104dfc>] pstate: 40000045
sp : ffffb925fa517940
[...]
[<ffff2b93b7104e20>] skcipher_walk_next+0x208/0x450
[<ffff2b93b710535c>] skcipher_walk_first+0x54/0x148
[<ffff2b93b7105664>] skcipher_walk_aead+0xd4/0x108
[<ffff2b93b6e77928>] ccm_encrypt+0x68/0x158
So clear the flag at the appropriate time.
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This patch adds the skcipher walk interface which replaces both
blkcipher walk and ablkcipher walk. Just like blkcipher walk it
can also be used for AEAD algorithms.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This patch removes the old crypto_grab_skcipher helper and replaces
it with crypto_grab_skcipher2.
As this is the final entry point into givcipher this patch also
removes all traces of the top-level givcipher interface, including
all implicit IV generators such as chainiv.
The bottom-level givcipher interface remains until the drivers
using it are converted.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This patch allows skcipher algorithms and instances to be created
and registered with the crypto API. They are accessible through
the top-level skcipher interface, along with ablkcipher/blkcipher
algorithms and instances.
This patch also introduces a new parameter called chunk size
which is meant for ciphers such as CTR and CTS which ostensibly
can handle arbitrary lengths, but still behave like block ciphers
in that you can only process a partial block at the very end.
For these ciphers the block size will continue to be set to 1
as it is now while the chunk size will be set to the underlying
block size.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
While converting ecryptfs over to skcipher I found that it needs
to pick a default key size if one isn't given. Rather than having
it poke into the guts of the algorithm to get max_keysize, let's
provide a helper that is meant to give a sane default (just in
case we ever get an algorithm that has no maximum key size).
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This patch adds a way for skcipher users to determine whether a key
is required by a transform.
Cc: stable@vger.kernel.org
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Fixes the following sparse warnings:
crypto/skcipher.c:94:5:
warning: symbol 'crypto_init_skcipher_ops_blkcipher'
was not declared. Should it be static?
crypto/skcipher.c:185:5:
warning: symbol 'crypto_init_skcipher_ops_ablkcipher'
was not declared. Should it be static?
Signed-off-by: Geliang Tang <geliangtang@163.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This patch introduces the crypto skcipher interface which aims
to replace both blkcipher and ablkcipher.
It's very similar to the existing ablkcipher interface. The
main difference is the removal of the givcrypt interface. In
order to make the transition easier for blkcipher users, there
is a helper SKCIPHER_REQUEST_ON_STACK which can be used to place
a request on the stack for synchronous transforms.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Eric Biggers
Denis Efremov
Linus Torvalds
Ondrej Mosnáček
Herbert Xu
Gideon Israel Dsouza
Ard Biesheuvel
Geliang Tang