[PATCH v2] crypto: vmx - Fix sleep-in-atomic bugs
Ondrej Mosnacek
omosnace at redhat.com
Sat Aug 25 06:01:20 AEST 2018
On Fri, Aug 24, 2018 at 9:39 PM Paulo Flabiano Smorigo
<pfsmorigo at linux.vnet.ibm.com> wrote:
> 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.
Great, thanks!
--
Ondrej Mosnacek <omosnace at redhat dot com>
Associate Software Engineer, Security Technologies
Red Hat, Inc.
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