[PATCH v2] crypto: vmx - Fix sleep-in-atomic bugs
Paulo Flabiano Smorigo
pfsmorigo at linux.vnet.ibm.com
Fri Aug 24 06:34:27 AEST 2018
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.
--
Paulo Flabiano Smorigo
IBM Linux Technology Center
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