From: Ondrej Mosnacek Subject: Re: [PATCH v2] crypto: vmx - Fix sleep-in-atomic bugs Date: Fri, 24 Aug 2018 22:01:20 +0200 Message-ID: References: <20180822062631.5664-1-omosnace@redhat.com> <20180823000446.GA26297@gallifrey> <11128af3ef7474136485261b5d53b679@linux.vnet.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Cc: Marcelo Henrique Cerri , Herbert Xu , linux-crypto@vger.kernel.org, Stephan Mueller , Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman , "Leonidas S . Barbosa" , linuxppc-dev@lists.ozlabs.org, stable@vger.kernel.org To: Paulo Flabiano Smorigo Return-path: In-Reply-To: Sender: stable-owner@vger.kernel.org List-Id: linux-crypto.vger.kernel.org On Fri, Aug 24, 2018 at 9:39 PM Paulo Flabiano Smorigo 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@vger.kernel.org > >>> Signed-off-by: Ondrej Mosnacek > >>> --- > >>> 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 Associate Software Engineer, Security Technologies Red Hat, Inc.