In the quest to remove all stack VLA usage from the kernel[1], this drops
AHASH_REQUEST_ON_STACK by preallocating the ahash request area combined
with the skcipher area (which are not used at the same time).
[1] https://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qPXydAacU1RqZWA@mail.gmail.com
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
The IV buffer used during CCM operations is used twice, during both the
hashing step and the ciphering step.
When using a hardware accelerator that updates the contents of the IV
buffer at the end of ciphering operations, the value will be modified.
In the decryption case, the subsequent setup of the hashing algorithm
will interpret the updated IV instead of the original value, which can
lead to out-of-bounds writes.
Reuse the idata buffer, only used in the hashing step, to preserve the
IV's value during the ciphering step in the decryption case.
Signed-off-by: Romain Izard <romain.izard.pro@gmail.com>
Reviewed-by: Tudor Ambarus <tudor.ambarus@microchip.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Commit f15f05b0a5 ("crypto: ccm - switch to separate cbcmac driver")
refactored the CCM driver to allow separate implementations of the
underlying MAC to be provided by a platform. However, in doing so, it
moved some data from the linear region to the stack, which violates the
SG constraints when the stack is virtually mapped.
So move idata/odata back to the request ctx struct, of which we can
reasonably expect that it has been allocated using kmalloc() et al.
Reported-by: Johannes Berg <johannes@sipsolutions.net>
Fixes: f15f05b0a5 ("crypto: ccm - switch to separate cbcmac driver")
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Tested-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
The CCM driver forces 32-bit alignment even if the underlying ciphers
don't care about alignment. This is because crypto_xor() used to require
this, but since this is no longer the case, drop the hardcoded minimum
of 32 bits.
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
The CCM driver was recently updated to defer the MAC part of the algorithm
to a dedicated crypto transform, and a template for instantiating such
transforms was added at the same time.
However, this new cbcmac template fails to take the alignmask of the
encapsulated cipher into account, which may result in buffer addresses
being passed down that are not sufficiently aligned.
So update the code to ensure that the digest buffer in the desc ctx
appears at a sufficiently aligned offset, and tweak the code so that all
calls to crypto_cipher_encrypt_one() operate on this buffer exclusively.
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Update the generic CCM driver to defer CBC-MAC processing to a
dedicated CBC-MAC ahash transform rather than open coding this
transform (and much of the associated scatterwalk plumbing) in
the CCM driver itself.
This cleans up the code considerably, but more importantly, it allows
the use of alternative CBC-MAC implementations that don't suffer from
performance degradation due to significant setup time (e.g., the NEON
based AES code needs to enable/disable the NEON, and load the S-box
into 16 SIMD registers, which cannot be amortized over the entire input
when using the cipher interface)
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Since commit 3a01d0ee2b ("crypto: skcipher - Remove top-level
givcipher interface"), crypto_spawn_skcipher2() and
crypto_spawn_skcipher() are equivalent. So switch callers of
crypto_spawn_skcipher2() to crypto_spawn_skcipher() and remove it.
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Since commit 3a01d0ee2b ("crypto: skcipher - Remove top-level
givcipher interface"), crypto_grab_skcipher2() and
crypto_grab_skcipher() are equivalent. So switch callers of
crypto_grab_skcipher2() to crypto_grab_skcipher() and remove it.
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This patch uses the crypto_aead_set_reqsize helper to avoid directly
touching the internals of aead.
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>
This prefixes all crypto module loading with "crypto-" so we never run
the risk of exposing module auto-loading to userspace via a crypto API,
as demonstrated by Mathias Krause:
https://lkml.org/lkml/2013/3/4/70
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
When comparing MAC hashes, AEAD authentication tags, or other hash
values in the context of authentication or integrity checking, it
is important not to leak timing information to a potential attacker,
i.e. when communication happens over a network.
Bytewise memory comparisons (such as memcmp) are usually optimized so
that they return a nonzero value as soon as a mismatch is found. E.g,
on x86_64/i5 for 512 bytes this can be ~50 cyc for a full mismatch
and up to ~850 cyc for a full match (cold). This early-return behavior
can leak timing information as a side channel, allowing an attacker to
iteratively guess the correct result.
This patch adds a new method crypto_memneq ("memory not equal to each
other") to the crypto API that compares memory areas of the same length
in roughly "constant time" (cache misses could change the timing, but
since they don't reveal information about the content of the strings
being compared, they are effectively benign). Iow, best and worst case
behaviour take the same amount of time to complete (in contrast to
memcmp).
Note that crypto_memneq (unlike memcmp) can only be used to test for
equality or inequality, NOT for lexicographical order. This, however,
is not an issue for its use-cases within the crypto API.
We tried to locate all of the places in the crypto API where memcmp was
being used for authentication or integrity checking, and convert them
over to crypto_memneq.
crypto_memneq is declared noinline, placed in its own source file,
and compiled with optimizations that might increase code size disabled
("Os") because a smart compiler (or LTO) might notice that the return
value is always compared against zero/nonzero, and might then
reintroduce the same early-return optimization that we are trying to
avoid.
Using #pragma or __attribute__ optimization annotations of the code
for disabling optimization was avoided as it seems to be considered
broken or unmaintained for long time in GCC [1]. Therefore, we work
around that by specifying the compile flag for memneq.o directly in
the Makefile. We found that this seems to be most appropriate.
As we use ("Os"), this patch also provides a loop-free "fast-path" for
frequently used 16 byte digests. Similarly to kernel library string
functions, leave an option for future even further optimized architecture
specific assembler implementations.
This was a joint work of James Yonan and Daniel Borkmann. Also thanks
for feedback from Florian Weimer on this and earlier proposals [2].
[1] http://gcc.gnu.org/ml/gcc/2012-07/msg00211.html
[2] https://lkml.org/lkml/2013/2/10/131
Signed-off-by: James Yonan <james@openvpn.net>
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Cc: Florian Weimer <fw@deneb.enyo.de>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Replace PTR_ERR followed by ERR_PTR by ERR_CAST, to be more concise.
The semantic patch that makes this change is as follows:
(http://coccinelle.lip6.fr/)
// <smpl>
@@
expression err,x;
@@
- err = PTR_ERR(x);
if (IS_ERR(x))
- return ERR_PTR(err);
+ return ERR_CAST(x);
// </smpl>
Signed-off-by: Julia Lawall <Julia.Lawall@lip6.fr>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Its a valid use case to have null associated data in a ccm vector, but
this case isn't being handled properly right now.
The following ccm decryption/verification test vector, using the
rfc4309 implementation regularly triggers a panic, as will any
other vector with null assoc data:
* key: ab2f8a74b71cd2b1ff802e487d82f8b9
* iv: c6fb7d800d13abd8a6b2d8
* Associated Data: [NULL]
* Tag Length: 8
* input: d5e8939fc7892e2b
The resulting panic looks like so:
Unable to handle kernel paging request at ffff810064ddaec0 RIP:
[<ffffffff8864c4d7>] :ccm:get_data_to_compute+0x1a6/0x1d6
PGD 8063 PUD 0
Oops: 0002 [1] SMP
last sysfs file: /module/libata/version
CPU 0
Modules linked in: crypto_tester_kmod(U) seqiv krng ansi_cprng chainiv rng ctr aes_generic aes_x86_64 ccm cryptomgr testmgr_cipher testmgr aead crypto_blkcipher crypto_a
lgapi des ipv6 xfrm_nalgo crypto_api autofs4 hidp l2cap bluetooth nfs lockd fscache nfs_acl sunrpc ip_conntrack_netbios_ns ipt_REJECT xt_state ip_conntrack nfnetlink xt_
tcpudp iptable_filter ip_tables x_tables dm_mirror dm_log dm_multipath scsi_dh dm_mod video hwmon backlight sbs i2c_ec button battery asus_acpi acpi_memhotplug ac lp sg
snd_intel8x0 snd_ac97_codec ac97_bus snd_seq_dummy snd_seq_oss joydev snd_seq_midi_event snd_seq snd_seq_device snd_pcm_oss snd_mixer_oss ide_cd snd_pcm floppy parport_p
c shpchp e752x_edac snd_timer e1000 i2c_i801 edac_mc snd soundcore snd_page_alloc i2c_core cdrom parport serio_raw pcspkr ata_piix libata sd_mod scsi_mod ext3 jbd uhci_h
cd ohci_hcd ehci_hcd
Pid: 12844, comm: crypto-tester Tainted: G 2.6.18-128.el5.fips1 #1
RIP: 0010:[<ffffffff8864c4d7>] [<ffffffff8864c4d7>] :ccm:get_data_to_compute+0x1a6/0x1d6
RSP: 0018:ffff8100134434e8 EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffff8100104898b0 RCX: ffffffffab6aea10
RDX: 0000000000000010 RSI: ffff8100104898c0 RDI: ffff810064ddaec0
RBP: 0000000000000000 R08: ffff8100104898b0 R09: 0000000000000000
R10: ffff8100103bac84 R11: ffff8100104898b0 R12: ffff810010489858
R13: ffff8100104898b0 R14: ffff8100103bac00 R15: 0000000000000000
FS: 00002ab881adfd30(0000) GS:ffffffff803ac000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b
CR2: ffff810064ddaec0 CR3: 0000000012a88000 CR4: 00000000000006e0
Process crypto-tester (pid: 12844, threadinfo ffff810013442000, task ffff81003d165860)
Stack: ffff8100103bac00 ffff8100104898e8 ffff8100134436f8 ffffffff00000000
0000000000000000 ffff8100104898b0 0000000000000000 ffff810010489858
0000000000000000 ffff8100103bac00 ffff8100134436f8 ffffffff8864c634
Call Trace:
[<ffffffff8864c634>] :ccm:crypto_ccm_auth+0x12d/0x140
[<ffffffff8864cf73>] :ccm:crypto_ccm_decrypt+0x161/0x23a
[<ffffffff88633643>] :crypto_tester_kmod:cavs_test_rfc4309_ccm+0x4a5/0x559
[...]
The above is from a RHEL5-based kernel, but upstream is susceptible too.
The fix is trivial: in crypto/ccm.c:crypto_ccm_auth(), pctx->ilen contains
whatever was in memory when pctx was allocated if assoclen is 0. The tested
fix is to simply add an else clause setting pctx->ilen to 0 for the
assoclen == 0 case, so that get_data_to_compute() doesn't try doing
things its not supposed to.
Signed-off-by: Jarod Wilson <jarod@redhat.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This patch adds Counter with CBC-MAC (CCM) support.
RFC 3610 and NIST Special Publication 800-38C were referenced.
Signed-off-by: Joy Latten <latten@austin.ibm.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
