RE: [RFC TLS Offload Support 00/15] cover letter
> >> TLS Tx crypto offload is a new feature of network devices. It enables > >> the kernel TLS socket to skip encryption and authentication > >> operations on the transmit side of the data path, delegating those to > >> the NIC. In turn, the NIC encrypts packets that belong to an > >> offloaded TLS socket on the fly. The NIC does not modify any packet > >> headers. It expects to receive fully framed TCP packets with TLS > >> records as payload. The NIC replaces plaintext with ciphertext and > >> fills the authentication tag. The NIC does not hold any state beyond > >> the context needed to encrypt the next expected packet, i.e. expected > >> TCP sequence number and crypto state. > > > > It seems like, since you do the TLS framing in TCP and the card is > > expecting to fill in certain aspects, there is a requirement that the > > packet contents aren't mangled between the TLS framing code and when > > the SKB hits the card. > > > > Is this right? > > > > For example, what happens if netfilter splits a TLS Tx offloaded frame > > into two TCP segments? We maintain the crypto context by tracking TCP sequence numbers, splitting TCP segments is not a problem. Even if reordering is introduced anywhere between TCP and the driver, we can identify it according to the TCP sequence number and handle it gracefully – see mlx_tls_tx_handler. > > Furthermore, it doesn't seem to work with bonding or any other virtual > interface, which could move the skb's to be processed on another NIC, as the > context is put onto the NIC. Even a redirect can not be processed anymore > (seems like those patches try to stick the connection to an interface anyway). > > Wouldn't it be possible to keep the state in software and push down a > security context per skb, which get applied during sending? If not possible > via > hw, slowpath can encrypt packet in sw. We do have all the state required to encrypt a TLS packet in software. But, pushing down the state for each skb is too expansive, because the state depends on all data in the TLS record, essentially it requires to resend the record up to that skb. This is accomplished for OOO packets in the “handle_ooo” function in mlx_tls. Maybe we could use that functionality to handle bonding, but at first it would be easier to prevent it. The slowpath you’ve mentioned is tricky, because you need to decide in advance that a TLS record will use the slowpath, because after the plaintext TLS record is pushed into TCP it is difficult to fallback to software crypto. > > Also sticking connections to outgoing interfaces might work for TX, but you > can't force the interface where packets come in. Right. This RFC handles only TX offload. > > Bye, > Hannes Thanks, Boris
Re: [RFC TLS Offload Support 00/15] cover letter
Hello, On 29.03.2017 19:41, David Miller wrote: > From: Aviad Yehezkel > Date: Tue, 28 Mar 2017 16:26:17 +0300 > >> TLS Tx crypto offload is a new feature of network devices. It >> enables the kernel TLS socket to skip encryption and authentication >> operations on the transmit side of the data path, delegating those >> to the NIC. In turn, the NIC encrypts packets that belong to an >> offloaded TLS socket on the fly. The NIC does not modify any packet >> headers. It expects to receive fully framed TCP packets with TLS >> records as payload. The NIC replaces plaintext with ciphertext and >> fills the authentication tag. The NIC does not hold any state beyond >> the context needed to encrypt the next expected packet, >> i.e. expected TCP sequence number and crypto state. > > It seems like, since you do the TLS framing in TCP and the card is > expecting to fill in certain aspects, there is a requirement that the > packet contents aren't mangled between the TLS framing code and when > the SKB hits the card. > > Is this right? > > For example, what happens if netfilter splits a TLS Tx offloaded frame > into two TCP segments? Furthermore, it doesn't seem to work with bonding or any other virtual interface, which could move the skb's to be processed on another NIC, as the context is put onto the NIC. Even a redirect can not be processed anymore (seems like those patches try to stick the connection to an interface anyway). Wouldn't it be possible to keep the state in software and push down a security context per skb, which get applied during sending? If not possible via hw, slowpath can encrypt packet in sw. Also sticking connections to outgoing interfaces might work for TX, but you can't force the interface where packets come in. Bye, Hannes
Re: [RFC TLS Offload Support 00/15] cover letter
From: Aviad Yehezkel Date: Tue, 28 Mar 2017 16:26:17 +0300 > TLS Tx crypto offload is a new feature of network devices. It > enables the kernel TLS socket to skip encryption and authentication > operations on the transmit side of the data path, delegating those > to the NIC. In turn, the NIC encrypts packets that belong to an > offloaded TLS socket on the fly. The NIC does not modify any packet > headers. It expects to receive fully framed TCP packets with TLS > records as payload. The NIC replaces plaintext with ciphertext and > fills the authentication tag. The NIC does not hold any state beyond > the context needed to encrypt the next expected packet, > i.e. expected TCP sequence number and crypto state. It seems like, since you do the TLS framing in TCP and the card is expecting to fill in certain aspects, there is a requirement that the packet contents aren't mangled between the TLS framing code and when the SKB hits the card. Is this right? For example, what happens if netfilter splits a TLS Tx offloaded frame into two TCP segments?
[RFC TLS Offload Support 00/15] cover letter
Overview A kernel TLS Tx only socket option for TCP sockets. Similarly to the kernel TLS socket(https://lwn.net/Articles/665602), only symmetric crypto is done in the kernel, as well as TLS record framing. The handshake remains in userspace, and the negotiated cipher keys/iv are provided to the TCP socket. Today, userspace TLS must perform 2 passes over the data. First, it has to encrypt the data. Second, the data is copied to the TCP socket in the kernel. Kernel TLS avoids one pass over the data by encrypting the data from userspace pages into kernelspace buffers. Non application-data TLS records must be encrypted using the latest crypto state available in the kernel. It is possible to get the crypto context from the kernel and encrypt such recrods in user-space. But we choose to encrypt such TLS records in the kernel by setting the MSG_OOB flag and providing the record type with the data. TLS Tx crypto offload is a new feature of network devices. It enables the kernel TLS socket to skip encryption and authentication operations on the transmit side of the data path, delegating those to the NIC. In turn, the NIC encrypts packets that belong to an offloaded TLS socket on the fly. The NIC does not modify any packet headers. It expects to receive fully framed TCP packets with TLS records as payload. The NIC replaces plaintext with ciphertext and fills the authentication tag. The NIC does not hold any state beyond the context needed to encrypt the next expected packet, i.e. expected TCP sequence number and crypto state. There are 2 flows for TLS Tx offload, a fast path and a slow path. Fast path: packet matches the expected TCP sequence number in the context. Slow path: packet does not match the expected TCP sequence number in the context. For example: TCP retransmissions. For a packet in the slow path, we need to resynchronize the crypto context of the NIC by providing the TLS record data for that packet before it could be encrypted and transmitted by the NIC. Motivation == 1) Performance: The CPU overhead of encryption in the data path is high, at least 4x for netperf over TLS between 2 machines connected back-to-back. Our single stream performance tests show that using crypto offload for TLS sockets achieves the same throughput as plain TCP traffic while increasing CPU utilization by only x1.4. 2) Flexibility: The protocol stack is implemented entirely on the host CPU. Compared to solutions based on TCP offload, this approach offloads only encryption. Keeping memory management, congestion control, etc. in the host CPU. Notes = 1) New paths: o net/tls - TLS layer in kernel o drivers/net/ethernet/mellanox/accelerator/* - NIC driver support, currently implemented as seperated modules. In the future this code will go into the mlx5 driver. We attached to this patch only the module that integrated with TLS layer. The complete NIC sample driver is available at https://github.com/Mellanox/tls-offload/tree/tx_rfc_v5 2) We implemented support for this API in OpenSSL 1.1.0, the code is available at https://github.com/Mellanox/tls-openssl/tree/master 3) TLS crypto offload was presented during netdevconf1.2, more details could be found in the presentation and paper: https://netdevconf.org/1.2/session.html?boris-pismenny 4) These RFC patches are based on kernel 4.9-rc7. Aviad Yehezkel (5): tcp: export do_tcp_sendpages function tcp: export tcp_rate_check_app_limited function tcp: Add TLS socket options for TCP sockets tls: tls offload support mlx/tls: Enable MLX5_CORE_QP_SIM mode for tls Dave Watson (2): crypto: Add gcm template for rfc5288 crypto: rfc5288 aesni optimized intel routines Ilya Lesokhin (8): tcp: Add clean acked data hook net: Add TLS offload netdevice and socket support mlx/mlx5_core: Allow sending multiple packets mlx/tls: Hardware interface mlx/tls: Sysfs configuration interface Configure the driver/hardware interface via sysfs. mlx/tls: Add mlx_accel offload driver for TLS mlx/tls: TLS offload driver Add the main module entrypoints and tie the module into the build system net/tls: Add software offload MAINTAINERS| 14 + arch/x86/crypto/aesni-intel_asm.S | 6 + arch/x86/crypto/aesni-intel_avx-x86_64.S | 4 + arch/x86/crypto/aesni-intel_glue.c | 105 ++- crypto/gcm.c | 122 crypto/tcrypt.c| 14 +- crypto/testmgr.c | 16 + crypto/testmgr.h | 47 ++ drivers/net/ethernet/mellanox/Kconfig | 1 + drivers/net/ethernet/mellanox/Makefile | 1 + .../net/ethernet/mellanox/accelerator/tls/Kconfig | 11 + .../net/ethernet/mellanox/accelerator/tls/Makefile | 4 + .../net/ethernet/mellanox/accelerator/tls/tls.c| 658 +++