The "hmac(sha3-224-generic)" algorithm has a descsize of 368 bytes,
which is greater than HASH_MAX_DESCSIZE (360) which is only enough for
sha3-224-generic. The check in shash_prepare_alg() doesn't catch this
because the HMAC template doesn't set descsize on the algorithms, but
rather sets it on each individual HMAC transform.
This causes a stack buffer overflow when SHASH_DESC_ON_STACK() is used
with hmac(sha3-224-generic).
Fix it by increasing HASH_MAX_DESCSIZE to the real maximum. Also add a
sanity check to hmac_init().
This was detected by the improved crypto self-tests in v5.2, by loading
the tcrypt module with CONFIG_CRYPTO_MANAGER_EXTRA_TESTS=y enabled. I
didn't notice this bug when I ran the self-tests by requesting the
algorithms via AF_ALG (i.e., not using tcrypt), probably because the
stack layout differs in the two cases and that made a difference here.
KASAN report:
BUG: KASAN: stack-out-of-bounds in memcpy include/linux/string.h:359 [inline]
BUG: KASAN: stack-out-of-bounds in shash_default_import+0x52/0x80 crypto/shash.c:223
Write of size 360 at addr ffff8880651defc8 by task insmod/3689
CPU: 2 PID: 3689 Comm: insmod Tainted: G E 5.1.0-10741-g35c99ffa20edd #11
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1 04/01/2014
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x86/0xc5 lib/dump_stack.c:113
print_address_description+0x7f/0x260 mm/kasan/report.c:188
__kasan_report+0x144/0x187 mm/kasan/report.c:317
kasan_report+0x12/0x20 mm/kasan/common.c:614
check_memory_region_inline mm/kasan/generic.c:185 [inline]
check_memory_region+0x137/0x190 mm/kasan/generic.c:191
memcpy+0x37/0x50 mm/kasan/common.c:125
memcpy include/linux/string.h:359 [inline]
shash_default_import+0x52/0x80 crypto/shash.c:223
crypto_shash_import include/crypto/hash.h:880 [inline]
hmac_import+0x184/0x240 crypto/hmac.c:102
hmac_init+0x96/0xc0 crypto/hmac.c:107
crypto_shash_init include/crypto/hash.h:902 [inline]
shash_digest_unaligned+0x9f/0xf0 crypto/shash.c:194
crypto_shash_digest+0xe9/0x1b0 crypto/shash.c:211
generate_random_hash_testvec.constprop.11+0x1ec/0x5b0 crypto/testmgr.c:1331
test_hash_vs_generic_impl+0x3f7/0x5c0 crypto/testmgr.c:1420
__alg_test_hash+0x26d/0x340 crypto/testmgr.c:1502
alg_test_hash+0x22e/0x330 crypto/testmgr.c:1552
alg_test.part.7+0x132/0x610 crypto/testmgr.c:4931
alg_test+0x1f/0x40 crypto/testmgr.c:4952
Fixes: b68a7ec1e9a3 ("crypto: hash - Remove VLA usage")
Reported-by: Corentin Labbe <clabbe.montjoie@gmail.com>
Cc: <stable@vger.kernel.org> # v4.20+
Cc: Kees Cook <keescook@chromium.org>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Tested-by: Corentin Labbe <clabbe.montjoie@gmail.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
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>
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 <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>
Many HMAC users directly use directly 0x36/0x5c values. It's better with crypto to use a name instead of directly some crypto constant. This patch simply add HMAC_IPAD_VALUE/HMAC_OPAD_VALUE defines in a new include file "crypto/hmac.h" and use them in crypto/hmac.c Signed-off-by: Corentin Labbe <clabbe.montjoie@gmail.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This adds the module loading prefix "crypto-" to the template lookup as well. For example, attempting to load 'vfat(blowfish)' via AF_ALG now correctly includes the "crypto-" prefix at every level, correctly rejecting "vfat": net-pf-38 algif-hash crypto-vfat(blowfish) crypto-vfat(blowfish)-all crypto-vfat Reported-by: Mathias Krause <minipli@googlemail.com> Signed-off-by: Kees Cook <keescook@chromium.org> Acked-by: Mathias Krause <minipli@googlemail.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Replaced the use of a Variable Length Array In Struct (VLAIS) with a C99 compliant equivalent. This patch allocates the appropriate amount of memory using a char array using the SHASH_DESC_ON_STACK macro. The new code can be compiled with both gcc and clang. Signed-off-by: Jan-Simon Möller <dl9pf@gmx.de> Signed-off-by: Behan Webster <behanw@converseincode.com> Reviewed-by: Mark Charlebois <charlebm@gmail.com> Acked-by: Herbert Xu <herbert@gondor.apana.org.au> Cc: pageexec@freemail.hu
percpu.h is included by sched.h and module.h and thus ends up being included when building most .c files. percpu.h includes slab.h which in turn includes gfp.h making everything defined by the two files universally available and complicating inclusion dependencies. percpu.h -> slab.h dependency is about to be removed. Prepare for this change by updating users of gfp and slab facilities include those headers directly instead of assuming availability. As this conversion needs to touch large number of source files, the following script is used as the basis of conversion. http://userweb.kernel.org/~tj/misc/slabh-sweep.py The script does the followings. * Scan files for gfp and slab usages and update includes such that only the necessary includes are there. ie. if only gfp is used, gfp.h, if slab is used, slab.h. * When the script inserts a new include, it looks at the include blocks and try to put the new include such that its order conforms to its surrounding. It's put in the include block which contains core kernel includes, in the same order that the rest are ordered - alphabetical, Christmas tree, rev-Xmas-tree or at the end if there doesn't seem to be any matching order. * If the script can't find a place to put a new include (mostly because the file doesn't have fitting include block), it prints out an error message indicating which .h file needs to be added to the file. The conversion was done in the following steps. 1. The initial automatic conversion of all .c files updated slightly over 4000 files, deleting around 700 includes and adding ~480 gfp.h and ~3000 slab.h inclusions. The script emitted errors for ~400 files. 2. Each error was manually checked. Some didn't need the inclusion, some needed manual addition while adding it to implementation .h or embedding .c file was more appropriate for others. This step added inclusions to around 150 files. 3. The script was run again and the output was compared to the edits from #2 to make sure no file was left behind. 4. Several build tests were done and a couple of problems were fixed. e.g. lib/decompress_*.c used malloc/free() wrappers around slab APIs requiring slab.h to be added manually. 5. The script was run on all .h files but without automatically editing them as sprinkling gfp.h and slab.h inclusions around .h files could easily lead to inclusion dependency hell. Most gfp.h inclusion directives were ignored as stuff from gfp.h was usually wildly available and often used in preprocessor macros. Each slab.h inclusion directive was examined and added manually as necessary. 6. percpu.h was updated not to include slab.h. 7. Build test were done on the following configurations and failures were fixed. CONFIG_GCOV_KERNEL was turned off for all tests (as my distributed build env didn't work with gcov compiles) and a few more options had to be turned off depending on archs to make things build (like ipr on powerpc/64 which failed due to missing writeq). * x86 and x86_64 UP and SMP allmodconfig and a custom test config. * powerpc and powerpc64 SMP allmodconfig * sparc and sparc64 SMP allmodconfig * ia64 SMP allmodconfig * s390 SMP allmodconfig * alpha SMP allmodconfig * um on x86_64 SMP allmodconfig 8. percpu.h modifications were reverted so that it could be applied as a separate patch and serve as bisection point. Given the fact that I had only a couple of failures from tests on step 6, I'm fairly confident about the coverage of this conversion patch. If there is a breakage, it's likely to be something in one of the arch headers which should be easily discoverable easily on most builds of the specific arch. Signed-off-by: Tejun Heo <tj@kernel.org> Guess-its-ok-by: Christoph Lameter <cl@linux-foundation.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
This patch uses crypto_shash_export/crypto_shash_import to prehash ipad/opad to speed up hmac. This is partly based on a similar patch by Steffen Klassert. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
If shash_alloc_instance() fails, we return the wrong error value. This patch fixes it. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>