[PATCH v2] crypto: vmx - Fix sleep-in-atomic bugs
Paulo Flabiano Smorigo
pfsmorigo at linux.vnet.ibm.com
Sat Aug 25 05:47:14 AEST 2018
On 2018-08-23 17:34, Paulo Flabiano Smorigo wrote:
> On 2018-08-22 21:04, Marcelo Henrique Cerri wrote:
>> That looks good to me. Maybe Paulo can help testing it.
>>
>> --
>> Regards,
>> Marcelo
>>
>> On Wed, Aug 22, 2018 at 08:26:31AM +0200, Ondrej Mosnacek wrote:
>>> This patch fixes sleep-in-atomic bugs in AES-CBC and AES-XTS VMX
>>> implementations. The problem is that the blkcipher_* functions should
>>> not be called in atomic context.
>>>
>>> The bugs can be reproduced via the AF_ALG interface by trying to
>>> encrypt/decrypt sufficiently large buffers (at least 64 KiB) using
>>> the
>>> VMX implementations of 'cbc(aes)' or 'xts(aes)'. Such operations then
>>> trigger BUG in crypto_yield():
>>>
>>> [ 891.863680] BUG: sleeping function called from invalid context at
>>> include/crypto/algapi.h:424
>>> [ 891.864622] in_atomic(): 1, irqs_disabled(): 0, pid: 12347, name:
>>> kcapi-enc
>>> [ 891.864739] 1 lock held by kcapi-enc/12347:
>>> [ 891.864811] #0: 00000000f5d42c46 (sk_lock-AF_ALG){+.+.}, at:
>>> skcipher_recvmsg+0x50/0x530
>>> [ 891.865076] CPU: 5 PID: 12347 Comm: kcapi-enc Not tainted
>>> 4.19.0-0.rc0.git3.1.fc30.ppc64le #1
>>> [ 891.865251] Call Trace:
>>> [ 891.865340] [c0000003387578c0] [c000000000d67ea4]
>>> dump_stack+0xe8/0x164 (unreliable)
>>> [ 891.865511] [c000000338757910] [c000000000172a58]
>>> ___might_sleep+0x2f8/0x310
>>> [ 891.865679] [c000000338757990] [c0000000006bff74]
>>> blkcipher_walk_done+0x374/0x4a0
>>> [ 891.865825] [c0000003387579e0] [d000000007e73e70]
>>> p8_aes_cbc_encrypt+0x1c8/0x260 [vmx_crypto]
>>> [ 891.865993] [c000000338757ad0] [c0000000006c0ee0]
>>> skcipher_encrypt_blkcipher+0x60/0x80
>>> [ 891.866128] [c000000338757b10] [c0000000006ec504]
>>> skcipher_recvmsg+0x424/0x530
>>> [ 891.866283] [c000000338757bd0] [c000000000b00654]
>>> sock_recvmsg+0x74/0xa0
>>> [ 891.866403] [c000000338757c10] [c000000000b00f64]
>>> ___sys_recvmsg+0xf4/0x2f0
>>> [ 891.866515] [c000000338757d90] [c000000000b02bb8]
>>> __sys_recvmsg+0x68/0xe0
>>> [ 891.866631] [c000000338757e30] [c00000000000bbe4]
>>> system_call+0x5c/0x70
>>>
>>> Fixes: 8c755ace357c ("crypto: vmx - Adding CBC routines for VMX
>>> module")
>>> Fixes: c07f5d3da643 ("crypto: vmx - Adding support for XTS")
>>> Cc: stable at vger.kernel.org
>>> Signed-off-by: Ondrej Mosnacek <omosnace at redhat.com>
>>> ---
>>> Still untested, please test and review if possible.
>>>
>>> Changes in v2:
>>> - fix leaving preemtption, etc. disabled when leaving the function
>>> (I switched to the more obvious and less efficient variant for the
>>> sake of clarity.)
>>>
>>> drivers/crypto/vmx/aes_cbc.c | 30 ++++++++++++++----------------
>>> drivers/crypto/vmx/aes_xts.c | 21 ++++++++++++++-------
>>> 2 files changed, 28 insertions(+), 23 deletions(-)
>>>
>>> diff --git a/drivers/crypto/vmx/aes_cbc.c
>>> b/drivers/crypto/vmx/aes_cbc.c
>>> index 5285ece4f33a..b71895871be3 100644
>>> --- a/drivers/crypto/vmx/aes_cbc.c
>>> +++ b/drivers/crypto/vmx/aes_cbc.c
>>> @@ -107,24 +107,23 @@ static int p8_aes_cbc_encrypt(struct
>>> blkcipher_desc *desc,
>>> ret = crypto_skcipher_encrypt(req);
>>> skcipher_request_zero(req);
>>> } else {
>>> - preempt_disable();
>>> - pagefault_disable();
>>> - enable_kernel_vsx();
>>> -
>>> blkcipher_walk_init(&walk, dst, src, nbytes);
>>> ret = blkcipher_walk_virt(desc, &walk);
>>> while ((nbytes = walk.nbytes)) {
>>> + preempt_disable();
>>> + pagefault_disable();
>>> + enable_kernel_vsx();
>>> aes_p8_cbc_encrypt(walk.src.virt.addr,
>>> walk.dst.virt.addr,
>>> nbytes & AES_BLOCK_MASK,
>>> &ctx->enc_key, walk.iv, 1);
>>> + disable_kernel_vsx();
>>> + pagefault_enable();
>>> + preempt_enable();
>>> +
>>> nbytes &= AES_BLOCK_SIZE - 1;
>>> ret = blkcipher_walk_done(desc, &walk, nbytes);
>>> }
>>> -
>>> - disable_kernel_vsx();
>>> - pagefault_enable();
>>> - preempt_enable();
>>> }
>>>
>>> return ret;
>>> @@ -147,24 +146,23 @@ static int p8_aes_cbc_decrypt(struct
>>> blkcipher_desc *desc,
>>> ret = crypto_skcipher_decrypt(req);
>>> skcipher_request_zero(req);
>>> } else {
>>> - preempt_disable();
>>> - pagefault_disable();
>>> - enable_kernel_vsx();
>>> -
>>> blkcipher_walk_init(&walk, dst, src, nbytes);
>>> ret = blkcipher_walk_virt(desc, &walk);
>>> while ((nbytes = walk.nbytes)) {
>>> + preempt_disable();
>>> + pagefault_disable();
>>> + enable_kernel_vsx();
>>> aes_p8_cbc_encrypt(walk.src.virt.addr,
>>> walk.dst.virt.addr,
>>> nbytes & AES_BLOCK_MASK,
>>> &ctx->dec_key, walk.iv, 0);
>>> + disable_kernel_vsx();
>>> + pagefault_enable();
>>> + preempt_enable();
>>> +
>>> nbytes &= AES_BLOCK_SIZE - 1;
>>> ret = blkcipher_walk_done(desc, &walk, nbytes);
>>> }
>>> -
>>> - disable_kernel_vsx();
>>> - pagefault_enable();
>>> - preempt_enable();
>>> }
>>>
>>> return ret;
>>> diff --git a/drivers/crypto/vmx/aes_xts.c
>>> b/drivers/crypto/vmx/aes_xts.c
>>> index 8bd9aff0f55f..e9954a7d4694 100644
>>> --- a/drivers/crypto/vmx/aes_xts.c
>>> +++ b/drivers/crypto/vmx/aes_xts.c
>>> @@ -116,32 +116,39 @@ static int p8_aes_xts_crypt(struct
>>> blkcipher_desc *desc,
>>> ret = enc? crypto_skcipher_encrypt(req) :
>>> crypto_skcipher_decrypt(req);
>>> skcipher_request_zero(req);
>>> } else {
>>> + blkcipher_walk_init(&walk, dst, src, nbytes);
>>> +
>>> + ret = blkcipher_walk_virt(desc, &walk);
>>> +
>>> preempt_disable();
>>> pagefault_disable();
>>> enable_kernel_vsx();
>>>
>>> - blkcipher_walk_init(&walk, dst, src, nbytes);
>>> -
>>> - ret = blkcipher_walk_virt(desc, &walk);
>>> iv = walk.iv;
>>> memset(tweak, 0, AES_BLOCK_SIZE);
>>> aes_p8_encrypt(iv, tweak, &ctx->tweak_key);
>>>
>>> + disable_kernel_vsx();
>>> + pagefault_enable();
>>> + preempt_enable();
>>> +
>>> while ((nbytes = walk.nbytes)) {
>>> + preempt_disable();
>>> + pagefault_disable();
>>> + enable_kernel_vsx();
>>> if (enc)
>>> aes_p8_xts_encrypt(walk.src.virt.addr, walk.dst.virt.addr,
>>> nbytes & AES_BLOCK_MASK, &ctx->enc_key, NULL, tweak);
>>> else
>>> aes_p8_xts_decrypt(walk.src.virt.addr, walk.dst.virt.addr,
>>> nbytes & AES_BLOCK_MASK, &ctx->dec_key, NULL, tweak);
>>> + disable_kernel_vsx();
>>> + pagefault_enable();
>>> + preempt_enable();
>>>
>>> nbytes &= AES_BLOCK_SIZE - 1;
>>> ret = blkcipher_walk_done(desc, &walk, nbytes);
>>> }
>>> -
>>> - disable_kernel_vsx();
>>> - pagefault_enable();
>>> - preempt_enable();
>>> }
>>> return ret;
>>> }
>>> --
>>> 2.17.1
>>>
>
> Sure thing. I'll test it later today. Thanks Ondrej for the fix.
Looks good to me. I made some tests here and no problem was found.
--
Paulo Flabiano Smorigo
IBM Linux Technology Center
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