Currently, almost none of the keyed hash algorithms check whether a key
has been set before proceeding. Some algorithms are okay with this and
will effectively just use a key of all 0's or some other bogus default.
However, others will severely break, as demonstrated using
"hmac(sha3-512-generic)", the unkeyed use of which causes a kernel crash
via a (potentially exploitable) stack buffer overflow.
A while ago, this problem was solved for AF_ALG by pairing each hash
transform with a 'has_key' bool. However, there are still other places
in the kernel where userspace can specify an arbitrary hash algorithm by
name, and the kernel uses it as unkeyed hash without checking whether it
is really unkeyed. Examples of this include:
- KEYCTL_DH_COMPUTE, via the KDF extension
- dm-verity
- dm-crypt, via the ESSIV support
- dm-integrity, via the "internal hash" mode with no key given
- drbd (Distributed Replicated Block Device)
This bug is especially bad for KEYCTL_DH_COMPUTE as that requires no
privileges to call.
Fix the bug for all users by adding a flag CRYPTO_TFM_NEED_KEY to the
->crt_flags of each hash transform that indicates whether the transform
still needs to be keyed or not. Then, make the hash init, import, and
digest functions return -ENOKEY if the key is still needed.
The new flag also replaces the 'has_key' bool which algif_hash was
previously using, thereby simplifying the algif_hash implementation.
Reported-by: syzbot <syzkaller@googlegroups.com>
Cc: stable@vger.kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Because the HMAC template didn't check that its underlying hash
algorithm is unkeyed, trying to use "hmac(hmac(sha3-512-generic))"
through AF_ALG or through KEYCTL_DH_COMPUTE resulted in the inner HMAC
being used without having been keyed, resulting in sha3_update() being
called without sha3_init(), causing a stack buffer overflow.
This is a very old bug, but it seems to have only started causing real
problems when SHA-3 support was added (requires CONFIG_CRYPTO_SHA3)
because the innermost hash's state is ->import()ed from a zeroed buffer,
and it just so happens that other hash algorithms are fine with that,
but SHA-3 is not. However, there could be arch or hardware-dependent
hash algorithms also affected; I couldn't test everything.
Fix the bug by introducing a function crypto_shash_alg_has_setkey()
which tests whether a shash algorithm is keyed. Then update the HMAC
template to require that its underlying hash algorithm is unkeyed.
Here is a reproducer:
#include <linux/if_alg.h>
#include <sys/socket.h>
int main()
{
int algfd;
struct sockaddr_alg addr = {
.salg_type = "hash",
.salg_name = "hmac(hmac(sha3-512-generic))",
};
char key[4096] = { 0 };
algfd = socket(AF_ALG, SOCK_SEQPACKET, 0);
bind(algfd, (const struct sockaddr *)&addr, sizeof(addr));
setsockopt(algfd, SOL_ALG, ALG_SET_KEY, key, sizeof(key));
}
Here was the KASAN report from syzbot:
BUG: KASAN: stack-out-of-bounds in memcpy include/linux/string.h:341 [inline]
BUG: KASAN: stack-out-of-bounds in sha3_update+0xdf/0x2e0 crypto/sha3_generic.c:161
Write of size 4096 at addr ffff8801cca07c40 by task syzkaller076574/3044
CPU: 1 PID: 3044 Comm: syzkaller076574 Not tainted 4.14.0-mm1+ #25
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:17 [inline]
dump_stack+0x194/0x257 lib/dump_stack.c:53
print_address_description+0x73/0x250 mm/kasan/report.c:252
kasan_report_error mm/kasan/report.c:351 [inline]
kasan_report+0x25b/0x340 mm/kasan/report.c:409
check_memory_region_inline mm/kasan/kasan.c:260 [inline]
check_memory_region+0x137/0x190 mm/kasan/kasan.c:267
memcpy+0x37/0x50 mm/kasan/kasan.c:303
memcpy include/linux/string.h:341 [inline]
sha3_update+0xdf/0x2e0 crypto/sha3_generic.c:161
crypto_shash_update+0xcb/0x220 crypto/shash.c:109
shash_finup_unaligned+0x2a/0x60 crypto/shash.c:151
crypto_shash_finup+0xc4/0x120 crypto/shash.c:165
hmac_finup+0x182/0x330 crypto/hmac.c:152
crypto_shash_finup+0xc4/0x120 crypto/shash.c:165
shash_digest_unaligned+0x9e/0xd0 crypto/shash.c:172
crypto_shash_digest+0xc4/0x120 crypto/shash.c:186
hmac_setkey+0x36a/0x690 crypto/hmac.c:66
crypto_shash_setkey+0xad/0x190 crypto/shash.c:64
shash_async_setkey+0x47/0x60 crypto/shash.c:207
crypto_ahash_setkey+0xaf/0x180 crypto/ahash.c:200
hash_setkey+0x40/0x90 crypto/algif_hash.c:446
alg_setkey crypto/af_alg.c:221 [inline]
alg_setsockopt+0x2a1/0x350 crypto/af_alg.c:254
SYSC_setsockopt net/socket.c:1851 [inline]
SyS_setsockopt+0x189/0x360 net/socket.c:1830
entry_SYSCALL_64_fastpath+0x1f/0x96
Reported-by: syzbot <syzkaller@googlegroups.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
The shash ahash digest adaptor function may crash if given a
zero-length input together with a null SG list. This is because
it tries to read the SG list before looking at the length.
This patch fixes it by checking the length first.
Cc: <stable@vger.kernel.org>
Reported-by: Stephan Müller<smueller@chronox.de>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Tested-by: Stephan Müller <smueller@chronox.de>
The SCTP program may sleep under a spinlock, and the function call path is:
sctp_generate_t3_rtx_event (acquire the spinlock)
sctp_do_sm
sctp_side_effects
sctp_cmd_interpreter
sctp_make_init_ack
sctp_pack_cookie
crypto_shash_setkey
shash_setkey_unaligned
kmalloc(GFP_KERNEL)
For the same reason, the orinoco driver may sleep in interrupt handler,
and the function call path is:
orinoco_rx_isr_tasklet
orinoco_rx
orinoco_mic
crypto_shash_setkey
shash_setkey_unaligned
kmalloc(GFP_KERNEL)
To fix it, GFP_KERNEL is replaced with GFP_ATOMIC.
This bug is found by my static analysis tool and my code review.
Signed-off-by: Jia-Ju Bai <baijiaju1990@163.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>
Pull crypto update from Herbert Xu:
"Here is the crypto update for 4.6:
API:
- Convert remaining crypto_hash users to shash or ahash, also convert
blkcipher/ablkcipher users to skcipher.
- Remove crypto_hash interface.
- Remove crypto_pcomp interface.
- Add crypto engine for async cipher drivers.
- Add akcipher documentation.
- Add skcipher documentation.
Algorithms:
- Rename crypto/crc32 to avoid name clash with lib/crc32.
- Fix bug in keywrap where we zero the wrong pointer.
Drivers:
- Support T5/M5, T7/M7 SPARC CPUs in n2 hwrng driver.
- Add PIC32 hwrng driver.
- Support BCM6368 in bcm63xx hwrng driver.
- Pack structs for 32-bit compat users in qat.
- Use crypto engine in omap-aes.
- Add support for sama5d2x SoCs in atmel-sha.
- Make atmel-sha available again.
- Make sahara hashing available again.
- Make ccp hashing available again.
- Make sha1-mb available again.
- Add support for multiple devices in ccp.
- Improve DMA performance in caam.
- Add hashing support to rockchip"
* 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6: (116 commits)
crypto: qat - remove redundant arbiter configuration
crypto: ux500 - fix checks of error code returned by devm_ioremap_resource()
crypto: atmel - fix checks of error code returned by devm_ioremap_resource()
crypto: qat - Change the definition of icp_qat_uof_regtype
hwrng: exynos - use __maybe_unused to hide pm functions
crypto: ccp - Add abstraction for device-specific calls
crypto: ccp - CCP versioning support
crypto: ccp - Support for multiple CCPs
crypto: ccp - Remove check for x86 family and model
crypto: ccp - memset request context to zero during import
lib/mpi: use "static inline" instead of "extern inline"
lib/mpi: avoid assembler warning
hwrng: bcm63xx - fix non device tree compatibility
crypto: testmgr - allow rfc3686 aes-ctr variants in fips mode.
crypto: qat - The AE id should be less than the maximal AE number
lib/mpi: Endianness fix
crypto: rockchip - add hash support for crypto engine in rk3288
crypto: xts - fix compile errors
crypto: doc - add skcipher API documentation
crypto: doc - update AEAD AD handling
...
This patch removes all traces of the crypto_hash interface, now
that everyone has switched over to shash or ahash.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
The has_key logic is wrong for shash algorithms as they always
have a setkey function. So we should instead be testing against
shash_no_setkey.
Fixes: a5596d6332 ("crypto: hash - Add crypto_ahash_has_setkey")
Cc: stable@vger.kernel.org
Reported-by: Stephan Mueller <smueller@chronox.de>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Tested-by: Stephan Mueller <smueller@chronox.de>
This patch adds a way for ahash users to determine whether a key
is required by a crypto_ahash transform.
Cc: stable@vger.kernel.org
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
__attribute__((aligned)) applies the default alignment for the largest scalar
type for the target ABI. gcc allows it to be applied inline to a defined type.
Clang only allows it to be applied to a type definition (PR11071).
Making it into 2 lines makes it more readable and works with both compilers.
Author: Mark Charlebois <charlebm@gmail.com>
Signed-off-by: Mark Charlebois <charlebm@gmail.com>
Signed-off-by: Behan Webster <behanw@converseincode.com>
Three errors resulting in kernel memory disclosure:
1/ The structures used for the netlink based crypto algorithm report API
are located on the stack. As snprintf() does not fill the remainder of
the buffer with null bytes, those stack bytes will be disclosed to users
of the API. Switch to strncpy() to fix this.
2/ crypto_report_one() does not initialize all field of struct
crypto_user_alg. Fix this to fix the heap info leak.
3/ For the module name we should copy only as many bytes as
module_name() returns -- not as much as the destination buffer could
hold. But the current code does not and therefore copies random data
from behind the end of the module name, as the module name is always
shorter than CRYPTO_MAX_ALG_NAME.
Also switch to use strncpy() to copy the algorithm's name and
driver_name. They are strings, after all.
Signed-off-by: Mathias Krause <minipli@googlemail.com>
Cc: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Add crypto_[un]register_shashes() to allow simplifying init/exit code of shash
crypto modules that register multiple algorithms.
Signed-off-by: Jussi Kivilinna <jussi.kivilinna@mbnet.fi>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
These macros contain a hidden goto, and are thus extremely error
prone and make code hard to audit.
Signed-off-by: David S. Miller <davem@davemloft.net>
The report functions use NLA_PUT so we need to ensure that NET
is enabled.
Reported-by: Luis Henriques <henrix@camandro.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
The function shash_async_import did not initialise the descriptor
correctly prior to calling the underlying shash import function.
This patch adds the required initialisation.
Reported-by: Miloslav Trmac <mitr@redhat.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
The macro CRYPTO_MINALIGN is not meant to be used directly. This
patch replaces it with crypto_tfm_ctx_alignment.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
crypto_init_shash_ops_async() tests for setkey and not for import
before exporting the algorithms import function to ahash.
This patch fixes this.
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This patch provides a default export/import function for all
shash algorithms. It simply copies the descriptor context as
is done by sha1_generic.
This in essence means that all existing shash algorithms now
support export/import. This is something that will be depended
upon in implementations such as hmac. Therefore all new shash
and ahash implementations must support export/import.
For those that cannot obtain a partial result, padlock-sha's
fallback model should be used so that a partial result is always
available.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
When shash_ahash_finup encounters a null request, we end up not
calling the underlying final function. This patch fixes that.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This patch exports the finup operation where available and adds
a default finup operation for ahash. The operations final, finup
and digest also will now deal with unaligned result pointers by
copying it. Finally export/import operations are will now be
exported too.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
When we encounter an unaligned pointer we are supposed to copy
it to a temporary aligned location. However the temporary buffer
isn't aligned properly. This patch fixes that.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Some unaligned buffers on the stack weren't zapped properly which
may cause secret data to be leaked. This patch fixes them by doing
a zero memset.
It is also possible for us to place random kernel stack contents
in the digest buffer if a digest operation fails. This is fixed
by only copying if the operation succeeded.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Now that all ahash implementations have been converted to the new
ahash type, we can remove old_ahash_alg and its associated support.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This patch converts crypto_ahash to the new style. The old ahash
algorithm type is retained until the existing ahash implementations
are also converted. All ahash users will automatically get the
new crypto_ahash type.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
As the extsize and init_tfm functions belong to the frontend the
frontend argument is superfluous.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This patch exports the async functions so that they can be reused
by cryptd when it switches over to using shash.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This patch changes descsize to a run-time attribute so that
implementations can change it in their init functions.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This patch moves the run-time null setkey check to shash_prepare_alg
just like we did for finup/digest.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This patch moves the run-time null finup/digest checks to the
shash_prepare_alg function which is run at registration time.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This patch replaces the full descriptor export with an export of
the partial hash state. This allows the use of a consistent export
format across all implementations of a given algorithm.
This is useful because a number of cases require the use of the
partial hash state, e.g., PadLock can use the SHA1 hash state
to get around the fact that it can only hash contiguous data
chunks.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This patch adds shash_register_instance so that shash instances
can be registered without bypassing the shash checks applied to
normal algorithms.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This patch adds the helper shash_attr_alg2 which locates a shash
algorithm based on the information in the given attribute.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This patch adds the functions needed to create and use shash
spawns, i.e., to use shash algorithms in a template.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This patch adds shash_instance and the associated alloc/free
functions. This is meant to be an instance that with a shash
algorithm under it. Note that the instance itself doesn't have
to be shash.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
When the total length is shorter than the calculated number of unaligned bytes, the call to shash->update breaks. For example, calling crc32c on unaligned buffer with length of 1 can result in a system crash.
Signed-off-by: Yehuda Sadeh <yehuda@hq.newdream.net>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This is based on a report and patch by Geert Uytterhoeven.
The functions crypto_alloc_tfm and create_create_tfm return a
pointer that needs to be adjusted by the caller when successful
and otherwise an error value. This means that the caller has
to check for the error and only perform the adjustment if the
pointer returned is valid.
Since all callers want to make the adjustment and we know how
to adjust it ourselves, it's much easier to just return adjusted
pointer directly.
The only caveat is that we have to return a void * instead of
struct crypto_tfm *. However, this isn't that bad because both
of these functions are for internal use only (by types code like
shash.c, not even algorithms code).
This patch also moves crypto_alloc_tfm into crypto/internal.h
(crypto_create_tfm is already there) to reflect this.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
We're currently checking the frontend type in init_tfm. This is
completely pointless because the fact that we're called at all
means that the frontend is ours so the type must match as well.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Module reference counting for shash is incorrect: when
a new shash transformation is created the refcount is not
increased as it should.
Signed-off-by: Adrian-Ken Rueegsegger <rueegsegger@swiss-it.ch>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Since most cryptographic hash algorithms have no keys, this patch
makes the setkey function optional for ahash and shash.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This patch allows shash algorithms to be used through the old hash
interface. This is a transitional measure so we can convert the
underlying algorithms to shash before converting the users across.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
It is often useful to save the partial state of a hash function
so that it can be used as a base for two or more computations.
The most prominent example is HMAC where all hashes start from
a base determined by the key. Having an import/export interface
means that we only have to compute that base once rather than
for each message.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This patch allows shash algorithms to be used through the ahash
interface. This is required before we can convert digest algorithms
over to shash.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
The shash interface replaces the current synchronous hash interface.
It improves over hash in two ways. Firstly shash is reentrant,
meaning that the same tfm may be used by two threads simultaneously
as all hashing state is stored in a local descriptor.
The other enhancement is that shash no longer takes scatter list
entries. This is because shash is specifically designed for
synchronous algorithms and as such scatter lists are unnecessary.
All existing hash users will be converted to shash once the
algorithms have been completely converted.
There is also a new finup function that combines update with final.
This will be extended to ahash once the algorithm conversion is
done.
This is also the first time that an algorithm type has their own
registration function. Existing algorithm types will be converted
to this way in due course.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Eric Biggers