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author | 2023-02-21 18:24:12 -0800 | |
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committer | 2023-02-21 18:24:12 -0800 | |
commit | 5b7c4cabbb65f5c469464da6c5f614cbd7f730f2 (patch) | |
tree | cc5c2d0a898769fd59549594fedb3ee6f84e59a0 /Documentation/networking/tls.rst | |
download | linux-5b7c4cabbb65f5c469464da6c5f614cbd7f730f2.tar.gz linux-5b7c4cabbb65f5c469464da6c5f614cbd7f730f2.zip |
Merge tag 'net-next-6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-nextgrafted
Pull networking updates from Jakub Kicinski:
"Core:
- Add dedicated kmem_cache for typical/small skb->head, avoid having
to access struct page at kfree time, and improve memory use.
- Introduce sysctl to set default RPS configuration for new netdevs.
- Define Netlink protocol specification format which can be used to
describe messages used by each family and auto-generate parsers.
Add tools for generating kernel data structures and uAPI headers.
- Expose all net/core sysctls inside netns.
- Remove 4s sleep in netpoll if carrier is instantly detected on
boot.
- Add configurable limit of MDB entries per port, and port-vlan.
- Continue populating drop reasons throughout the stack.
- Retire a handful of legacy Qdiscs and classifiers.
Protocols:
- Support IPv4 big TCP (TSO frames larger than 64kB).
- Add IP_LOCAL_PORT_RANGE socket option, to control local port range
on socket by socket basis.
- Track and report in procfs number of MPTCP sockets used.
- Support mixing IPv4 and IPv6 flows in the in-kernel MPTCP path
manager.
- IPv6: don't check net.ipv6.route.max_size and rely on garbage
collection to free memory (similarly to IPv4).
- Support Penultimate Segment Pop (PSP) flavor in SRv6 (RFC8986).
- ICMP: add per-rate limit counters.
- Add support for user scanning requests in ieee802154.
- Remove static WEP support.
- Support minimal Wi-Fi 7 Extremely High Throughput (EHT) rate
reporting.
- WiFi 7 EHT channel puncturing support (client & AP).
BPF:
- Add a rbtree data structure following the "next-gen data structure"
precedent set by recently added linked list, that is, by using
kfunc + kptr instead of adding a new BPF map type.
- Expose XDP hints via kfuncs with initial support for RX hash and
timestamp metadata.
- Add BPF_F_NO_TUNNEL_KEY extension to bpf_skb_set_tunnel_key to
better support decap on GRE tunnel devices not operating in collect
metadata.
- Improve x86 JIT's codegen for PROBE_MEM runtime error checks.
- Remove the need for trace_printk_lock for bpf_trace_printk and
bpf_trace_vprintk helpers.
- Extend libbpf's bpf_tracing.h support for tracing arguments of
kprobes/uprobes and syscall as a special case.
- Significantly reduce the search time for module symbols by
livepatch and BPF.
- Enable cpumasks to be used as kptrs, which is useful for tracing
programs tracking which tasks end up running on which CPUs in
different time intervals.
- Add support for BPF trampoline on s390x and riscv64.
- Add capability to export the XDP features supported by the NIC.
- Add __bpf_kfunc tag for marking kernel functions as kfuncs.
- Add cgroup.memory=nobpf kernel parameter option to disable BPF
memory accounting for container environments.
Netfilter:
- Remove the CLUSTERIP target. It has been marked as obsolete for
years, and we still have WARN splats wrt races of the out-of-band
/proc interface installed by this target.
- Add 'destroy' commands to nf_tables. They are identical to the
existing 'delete' commands, but do not return an error if the
referenced object (set, chain, rule...) did not exist.
Driver API:
- Improve cpumask_local_spread() locality to help NICs set the right
IRQ affinity on AMD platforms.
- Separate C22 and C45 MDIO bus transactions more clearly.
- Introduce new DCB table to control DSCP rewrite on egress.
- Support configuration of Physical Layer Collision Avoidance (PLCA)
Reconciliation Sublayer (RS) (802.3cg-2019). Modern version of
shared medium Ethernet.
- Support for MAC Merge layer (IEEE 802.3-2018 clause 99). Allowing
preemption of low priority frames by high priority frames.
- Add support for controlling MACSec offload using netlink SET.
- Rework devlink instance refcounts to allow registration and
de-registration under the instance lock. Split the code into
multiple files, drop some of the unnecessarily granular locks and
factor out common parts of netlink operation handling.
- Add TX frame aggregation parameters (for USB drivers).
- Add a new attr TCA_EXT_WARN_MSG to report TC (offload) warning
messages with notifications for debug.
- Allow offloading of UDP NEW connections via act_ct.
- Add support for per action HW stats in TC.
- Support hardware miss to TC action (continue processing in SW from
a specific point in the action chain).
- Warn if old Wireless Extension user space interface is used with
modern cfg80211/mac80211 drivers. Do not support Wireless
Extensions for Wi-Fi 7 devices at all. Everyone should switch to
using nl80211 interface instead.
- Improve the CAN bit timing configuration. Use extack to return
error messages directly to user space, update the SJW handling,
including the definition of a new default value that will benefit
CAN-FD controllers, by increasing their oscillator tolerance.
New hardware / drivers:
- Ethernet:
- nVidia BlueField-3 support (control traffic driver)
- Ethernet support for imx93 SoCs
- Motorcomm yt8531 gigabit Ethernet PHY
- onsemi NCN26000 10BASE-T1S PHY (with support for PLCA)
- Microchip LAN8841 PHY (incl. cable diagnostics and PTP)
- Amlogic gxl MDIO mux
- WiFi:
- RealTek RTL8188EU (rtl8xxxu)
- Qualcomm Wi-Fi 7 devices (ath12k)
- CAN:
- Renesas R-Car V4H
Drivers:
- Bluetooth:
- Set Per Platform Antenna Gain (PPAG) for Intel controllers.
- Ethernet NICs:
- Intel (1G, igc):
- support TSN / Qbv / packet scheduling features of i226 model
- Intel (100G, ice):
- use GNSS subsystem instead of TTY
- multi-buffer XDP support
- extend support for GPIO pins to E823 devices
- nVidia/Mellanox:
- update the shared buffer configuration on PFC commands
- implement PTP adjphase function for HW offset control
- TC support for Geneve and GRE with VF tunnel offload
- more efficient crypto key management method
- multi-port eswitch support
- Netronome/Corigine:
- add DCB IEEE support
- support IPsec offloading for NFP3800
- Freescale/NXP (enetc):
- support XDP_REDIRECT for XDP non-linear buffers
- improve reconfig, avoid link flap and waiting for idle
- support MAC Merge layer
- Other NICs:
- sfc/ef100: add basic devlink support for ef100
- ionic: rx_push mode operation (writing descriptors via MMIO)
- bnxt: use the auxiliary bus abstraction for RDMA
- r8169: disable ASPM and reset bus in case of tx timeout
- cpsw: support QSGMII mode for J721e CPSW9G
- cpts: support pulse-per-second output
- ngbe: add an mdio bus driver
- usbnet: optimize usbnet_bh() by avoiding unnecessary queuing
- r8152: handle devices with FW with NCM support
- amd-xgbe: support 10Mbps, 2.5GbE speeds and rx-adaptation
- virtio-net: support multi buffer XDP
- virtio/vsock: replace virtio_vsock_pkt with sk_buff
- tsnep: XDP support
- Ethernet high-speed switches:
- nVidia/Mellanox (mlxsw):
- add support for latency TLV (in FW control messages)
- Microchip (sparx5):
- separate explicit and implicit traffic forwarding rules, make
the implicit rules always active
- add support for egress DSCP rewrite
- IS0 VCAP support (Ingress Classification)
- IS2 VCAP filters (protos, L3 addrs, L4 ports, flags, ToS
etc.)
- ES2 VCAP support (Egress Access Control)
- support for Per-Stream Filtering and Policing (802.1Q,
8.6.5.1)
- Ethernet embedded switches:
- Marvell (mv88e6xxx):
- add MAB (port auth) offload support
- enable PTP receive for mv88e6390
- NXP (ocelot):
- support MAC Merge layer
- support for the the vsc7512 internal copper phys
- Microchip:
- lan9303: convert to PHYLINK
- lan966x: support TC flower filter statistics
- lan937x: PTP support for KSZ9563/KSZ8563 and LAN937x
- lan937x: support Credit Based Shaper configuration
- ksz9477: support Energy Efficient Ethernet
- other:
- qca8k: convert to regmap read/write API, use bulk operations
- rswitch: Improve TX timestamp accuracy
- Intel WiFi (iwlwifi):
- EHT (Wi-Fi 7) rate reporting
- STEP equalizer support: transfer some STEP (connection to radio
on platforms with integrated wifi) related parameters from the
BIOS to the firmware.
- Qualcomm 802.11ax WiFi (ath11k):
- IPQ5018 support
- Fine Timing Measurement (FTM) responder role support
- channel 177 support
- MediaTek WiFi (mt76):
- per-PHY LED support
- mt7996: EHT (Wi-Fi 7) support
- Wireless Ethernet Dispatch (WED) reset support
- switch to using page pool allocator
- RealTek WiFi (rtw89):
- support new version of Bluetooth co-existance
- Mobile:
- rmnet: support TX aggregation"
* tag 'net-next-6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next: (1872 commits)
page_pool: add a comment explaining the fragment counter usage
net: ethtool: fix __ethtool_dev_mm_supported() implementation
ethtool: pse-pd: Fix double word in comments
xsk: add linux/vmalloc.h to xsk.c
sefltests: netdevsim: wait for devlink instance after netns removal
selftest: fib_tests: Always cleanup before exit
net/mlx5e: Align IPsec ASO result memory to be as required by hardware
net/mlx5e: TC, Set CT miss to the specific ct action instance
net/mlx5e: Rename CHAIN_TO_REG to MAPPED_OBJ_TO_REG
net/mlx5: Refactor tc miss handling to a single function
net/mlx5: Kconfig: Make tc offload depend on tc skb extension
net/sched: flower: Support hardware miss to tc action
net/sched: flower: Move filter handle initialization earlier
net/sched: cls_api: Support hardware miss to tc action
net/sched: Rename user cookie and act cookie
sfc: fix builds without CONFIG_RTC_LIB
sfc: clean up some inconsistent indentings
net/mlx4_en: Introduce flexible array to silence overflow warning
net: lan966x: Fix possible deadlock inside PTP
net/ulp: Remove redundant ->clone() test in inet_clone_ulp().
...
Diffstat (limited to 'Documentation/networking/tls.rst')
-rw-r--r-- | Documentation/networking/tls.rst | 288 |
1 files changed, 288 insertions, 0 deletions
diff --git a/Documentation/networking/tls.rst b/Documentation/networking/tls.rst new file mode 100644 index 000000000..658ed3a71 --- /dev/null +++ b/Documentation/networking/tls.rst @@ -0,0 +1,288 @@ +.. _kernel_tls: + +========== +Kernel TLS +========== + +Overview +======== + +Transport Layer Security (TLS) is a Upper Layer Protocol (ULP) that runs over +TCP. TLS provides end-to-end data integrity and confidentiality. + +User interface +============== + +Creating a TLS connection +------------------------- + +First create a new TCP socket and set the TLS ULP. + +.. code-block:: c + + sock = socket(AF_INET, SOCK_STREAM, 0); + setsockopt(sock, SOL_TCP, TCP_ULP, "tls", sizeof("tls")); + +Setting the TLS ULP allows us to set/get TLS socket options. Currently +only the symmetric encryption is handled in the kernel. After the TLS +handshake is complete, we have all the parameters required to move the +data-path to the kernel. There is a separate socket option for moving +the transmit and the receive into the kernel. + +.. code-block:: c + + /* From linux/tls.h */ + struct tls_crypto_info { + unsigned short version; + unsigned short cipher_type; + }; + + struct tls12_crypto_info_aes_gcm_128 { + struct tls_crypto_info info; + unsigned char iv[TLS_CIPHER_AES_GCM_128_IV_SIZE]; + unsigned char key[TLS_CIPHER_AES_GCM_128_KEY_SIZE]; + unsigned char salt[TLS_CIPHER_AES_GCM_128_SALT_SIZE]; + unsigned char rec_seq[TLS_CIPHER_AES_GCM_128_REC_SEQ_SIZE]; + }; + + + struct tls12_crypto_info_aes_gcm_128 crypto_info; + + crypto_info.info.version = TLS_1_2_VERSION; + crypto_info.info.cipher_type = TLS_CIPHER_AES_GCM_128; + memcpy(crypto_info.iv, iv_write, TLS_CIPHER_AES_GCM_128_IV_SIZE); + memcpy(crypto_info.rec_seq, seq_number_write, + TLS_CIPHER_AES_GCM_128_REC_SEQ_SIZE); + memcpy(crypto_info.key, cipher_key_write, TLS_CIPHER_AES_GCM_128_KEY_SIZE); + memcpy(crypto_info.salt, implicit_iv_write, TLS_CIPHER_AES_GCM_128_SALT_SIZE); + + setsockopt(sock, SOL_TLS, TLS_TX, &crypto_info, sizeof(crypto_info)); + +Transmit and receive are set separately, but the setup is the same, using either +TLS_TX or TLS_RX. + +Sending TLS application data +---------------------------- + +After setting the TLS_TX socket option all application data sent over this +socket is encrypted using TLS and the parameters provided in the socket option. +For example, we can send an encrypted hello world record as follows: + +.. code-block:: c + + const char *msg = "hello world\n"; + send(sock, msg, strlen(msg)); + +send() data is directly encrypted from the userspace buffer provided +to the encrypted kernel send buffer if possible. + +The sendfile system call will send the file's data over TLS records of maximum +length (2^14). + +.. code-block:: c + + file = open(filename, O_RDONLY); + fstat(file, &stat); + sendfile(sock, file, &offset, stat.st_size); + +TLS records are created and sent after each send() call, unless +MSG_MORE is passed. MSG_MORE will delay creation of a record until +MSG_MORE is not passed, or the maximum record size is reached. + +The kernel will need to allocate a buffer for the encrypted data. +This buffer is allocated at the time send() is called, such that +either the entire send() call will return -ENOMEM (or block waiting +for memory), or the encryption will always succeed. If send() returns +-ENOMEM and some data was left on the socket buffer from a previous +call using MSG_MORE, the MSG_MORE data is left on the socket buffer. + +Receiving TLS application data +------------------------------ + +After setting the TLS_RX socket option, all recv family socket calls +are decrypted using TLS parameters provided. A full TLS record must +be received before decryption can happen. + +.. code-block:: c + + char buffer[16384]; + recv(sock, buffer, 16384); + +Received data is decrypted directly in to the user buffer if it is +large enough, and no additional allocations occur. If the userspace +buffer is too small, data is decrypted in the kernel and copied to +userspace. + +``EINVAL`` is returned if the TLS version in the received message does not +match the version passed in setsockopt. + +``EMSGSIZE`` is returned if the received message is too big. + +``EBADMSG`` is returned if decryption failed for any other reason. + +Send TLS control messages +------------------------- + +Other than application data, TLS has control messages such as alert +messages (record type 21) and handshake messages (record type 22), etc. +These messages can be sent over the socket by providing the TLS record type +via a CMSG. For example the following function sends @data of @length bytes +using a record of type @record_type. + +.. code-block:: c + + /* send TLS control message using record_type */ + static int klts_send_ctrl_message(int sock, unsigned char record_type, + void *data, size_t length) + { + struct msghdr msg = {0}; + int cmsg_len = sizeof(record_type); + struct cmsghdr *cmsg; + char buf[CMSG_SPACE(cmsg_len)]; + struct iovec msg_iov; /* Vector of data to send/receive into. */ + + msg.msg_control = buf; + msg.msg_controllen = sizeof(buf); + cmsg = CMSG_FIRSTHDR(&msg); + cmsg->cmsg_level = SOL_TLS; + cmsg->cmsg_type = TLS_SET_RECORD_TYPE; + cmsg->cmsg_len = CMSG_LEN(cmsg_len); + *CMSG_DATA(cmsg) = record_type; + msg.msg_controllen = cmsg->cmsg_len; + + msg_iov.iov_base = data; + msg_iov.iov_len = length; + msg.msg_iov = &msg_iov; + msg.msg_iovlen = 1; + + return sendmsg(sock, &msg, 0); + } + +Control message data should be provided unencrypted, and will be +encrypted by the kernel. + +Receiving TLS control messages +------------------------------ + +TLS control messages are passed in the userspace buffer, with message +type passed via cmsg. If no cmsg buffer is provided, an error is +returned if a control message is received. Data messages may be +received without a cmsg buffer set. + +.. code-block:: c + + char buffer[16384]; + char cmsg[CMSG_SPACE(sizeof(unsigned char))]; + struct msghdr msg = {0}; + msg.msg_control = cmsg; + msg.msg_controllen = sizeof(cmsg); + + struct iovec msg_iov; + msg_iov.iov_base = buffer; + msg_iov.iov_len = 16384; + + msg.msg_iov = &msg_iov; + msg.msg_iovlen = 1; + + int ret = recvmsg(sock, &msg, 0 /* flags */); + + struct cmsghdr *cmsg = CMSG_FIRSTHDR(&msg); + if (cmsg->cmsg_level == SOL_TLS && + cmsg->cmsg_type == TLS_GET_RECORD_TYPE) { + int record_type = *((unsigned char *)CMSG_DATA(cmsg)); + // Do something with record_type, and control message data in + // buffer. + // + // Note that record_type may be == to application data (23). + } else { + // Buffer contains application data. + } + +recv will never return data from mixed types of TLS records. + +Integrating in to userspace TLS library +--------------------------------------- + +At a high level, the kernel TLS ULP is a replacement for the record +layer of a userspace TLS library. + +A patchset to OpenSSL to use ktls as the record layer is +`here <https://github.com/Mellanox/openssl/commits/tls_rx2>`_. + +`An example <https://github.com/ktls/af_ktls-tool/commits/RX>`_ +of calling send directly after a handshake using gnutls. +Since it doesn't implement a full record layer, control +messages are not supported. + +Optional optimizations +---------------------- + +There are certain condition-specific optimizations the TLS ULP can make, +if requested. Those optimizations are either not universally beneficial +or may impact correctness, hence they require an opt-in. +All options are set per-socket using setsockopt(), and their +state can be checked using getsockopt() and via socket diag (``ss``). + +TLS_TX_ZEROCOPY_RO +~~~~~~~~~~~~~~~~~~ + +For device offload only. Allow sendfile() data to be transmitted directly +to the NIC without making an in-kernel copy. This allows true zero-copy +behavior when device offload is enabled. + +The application must make sure that the data is not modified between being +submitted and transmission completing. In other words this is mostly +applicable if the data sent on a socket via sendfile() is read-only. + +Modifying the data may result in different versions of the data being used +for the original TCP transmission and TCP retransmissions. To the receiver +this will look like TLS records had been tampered with and will result +in record authentication failures. + +TLS_RX_EXPECT_NO_PAD +~~~~~~~~~~~~~~~~~~~~ + +TLS 1.3 only. Expect the sender to not pad records. This allows the data +to be decrypted directly into user space buffers with TLS 1.3. + +This optimization is safe to enable only if the remote end is trusted, +otherwise it is an attack vector to doubling the TLS processing cost. + +If the record decrypted turns out to had been padded or is not a data +record it will be decrypted again into a kernel buffer without zero copy. +Such events are counted in the ``TlsDecryptRetry`` statistic. + +Statistics +========== + +TLS implementation exposes the following per-namespace statistics +(``/proc/net/tls_stat``): + +- ``TlsCurrTxSw``, ``TlsCurrRxSw`` - + number of TX and RX sessions currently installed where host handles + cryptography + +- ``TlsCurrTxDevice``, ``TlsCurrRxDevice`` - + number of TX and RX sessions currently installed where NIC handles + cryptography + +- ``TlsTxSw``, ``TlsRxSw`` - + number of TX and RX sessions opened with host cryptography + +- ``TlsTxDevice``, ``TlsRxDevice`` - + number of TX and RX sessions opened with NIC cryptography + +- ``TlsDecryptError`` - + record decryption failed (e.g. due to incorrect authentication tag) + +- ``TlsDeviceRxResync`` - + number of RX resyncs sent to NICs handling cryptography + +- ``TlsDecryptRetry`` - + number of RX records which had to be re-decrypted due to + ``TLS_RX_EXPECT_NO_PAD`` mis-prediction. Note that this counter will + also increment for non-data records. + +- ``TlsRxNoPadViolation`` - + number of data RX records which had to be re-decrypted due to + ``TLS_RX_EXPECT_NO_PAD`` mis-prediction. |