aboutsummaryrefslogtreecommitdiff
path: root/Documentation/admin-guide/device-mapper/dm-integrity.rst
diff options
context:
space:
mode:
authorLibravatar Linus Torvalds <torvalds@linux-foundation.org>2023-02-21 18:24:12 -0800
committerLibravatar Linus Torvalds <torvalds@linux-foundation.org>2023-02-21 18:24:12 -0800
commit5b7c4cabbb65f5c469464da6c5f614cbd7f730f2 (patch)
treecc5c2d0a898769fd59549594fedb3ee6f84e59a0 /Documentation/admin-guide/device-mapper/dm-integrity.rst
downloadlinux-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/admin-guide/device-mapper/dm-integrity.rst')
-rw-r--r--Documentation/admin-guide/device-mapper/dm-integrity.rst292
1 files changed, 292 insertions, 0 deletions
diff --git a/Documentation/admin-guide/device-mapper/dm-integrity.rst b/Documentation/admin-guide/device-mapper/dm-integrity.rst
new file mode 100644
index 000000000..8db172efa
--- /dev/null
+++ b/Documentation/admin-guide/device-mapper/dm-integrity.rst
@@ -0,0 +1,292 @@
+============
+dm-integrity
+============
+
+The dm-integrity target emulates a block device that has additional
+per-sector tags that can be used for storing integrity information.
+
+A general problem with storing integrity tags with every sector is that
+writing the sector and the integrity tag must be atomic - i.e. in case of
+crash, either both sector and integrity tag or none of them is written.
+
+To guarantee write atomicity, the dm-integrity target uses journal, it
+writes sector data and integrity tags into a journal, commits the journal
+and then copies the data and integrity tags to their respective location.
+
+The dm-integrity target can be used with the dm-crypt target - in this
+situation the dm-crypt target creates the integrity data and passes them
+to the dm-integrity target via bio_integrity_payload attached to the bio.
+In this mode, the dm-crypt and dm-integrity targets provide authenticated
+disk encryption - if the attacker modifies the encrypted device, an I/O
+error is returned instead of random data.
+
+The dm-integrity target can also be used as a standalone target, in this
+mode it calculates and verifies the integrity tag internally. In this
+mode, the dm-integrity target can be used to detect silent data
+corruption on the disk or in the I/O path.
+
+There's an alternate mode of operation where dm-integrity uses bitmap
+instead of a journal. If a bit in the bitmap is 1, the corresponding
+region's data and integrity tags are not synchronized - if the machine
+crashes, the unsynchronized regions will be recalculated. The bitmap mode
+is faster than the journal mode, because we don't have to write the data
+twice, but it is also less reliable, because if data corruption happens
+when the machine crashes, it may not be detected.
+
+When loading the target for the first time, the kernel driver will format
+the device. But it will only format the device if the superblock contains
+zeroes. If the superblock is neither valid nor zeroed, the dm-integrity
+target can't be loaded.
+
+To use the target for the first time:
+
+1. overwrite the superblock with zeroes
+2. load the dm-integrity target with one-sector size, the kernel driver
+ will format the device
+3. unload the dm-integrity target
+4. read the "provided_data_sectors" value from the superblock
+5. load the dm-integrity target with the target size
+ "provided_data_sectors"
+6. if you want to use dm-integrity with dm-crypt, load the dm-crypt target
+ with the size "provided_data_sectors"
+
+
+Target arguments:
+
+1. the underlying block device
+
+2. the number of reserved sector at the beginning of the device - the
+ dm-integrity won't read of write these sectors
+
+3. the size of the integrity tag (if "-" is used, the size is taken from
+ the internal-hash algorithm)
+
+4. mode:
+
+ D - direct writes (without journal)
+ in this mode, journaling is
+ not used and data sectors and integrity tags are written
+ separately. In case of crash, it is possible that the data
+ and integrity tag doesn't match.
+ J - journaled writes
+ data and integrity tags are written to the
+ journal and atomicity is guaranteed. In case of crash,
+ either both data and tag or none of them are written. The
+ journaled mode degrades write throughput twice because the
+ data have to be written twice.
+ B - bitmap mode - data and metadata are written without any
+ synchronization, the driver maintains a bitmap of dirty
+ regions where data and metadata don't match. This mode can
+ only be used with internal hash.
+ R - recovery mode - in this mode, journal is not replayed,
+ checksums are not checked and writes to the device are not
+ allowed. This mode is useful for data recovery if the
+ device cannot be activated in any of the other standard
+ modes.
+
+5. the number of additional arguments
+
+Additional arguments:
+
+journal_sectors:number
+ The size of journal, this argument is used only if formatting the
+ device. If the device is already formatted, the value from the
+ superblock is used.
+
+interleave_sectors:number
+ The number of interleaved sectors. This values is rounded down to
+ a power of two. If the device is already formatted, the value from
+ the superblock is used.
+
+meta_device:device
+ Don't interleave the data and metadata on the device. Use a
+ separate device for metadata.
+
+buffer_sectors:number
+ The number of sectors in one buffer. The value is rounded down to
+ a power of two.
+
+ The tag area is accessed using buffers, the buffer size is
+ configurable. The large buffer size means that the I/O size will
+ be larger, but there could be less I/Os issued.
+
+journal_watermark:number
+ The journal watermark in percents. When the size of the journal
+ exceeds this watermark, the thread that flushes the journal will
+ be started.
+
+commit_time:number
+ Commit time in milliseconds. When this time passes, the journal is
+ written. The journal is also written immediately if the FLUSH
+ request is received.
+
+internal_hash:algorithm(:key) (the key is optional)
+ Use internal hash or crc.
+ When this argument is used, the dm-integrity target won't accept
+ integrity tags from the upper target, but it will automatically
+ generate and verify the integrity tags.
+
+ You can use a crc algorithm (such as crc32), then integrity target
+ will protect the data against accidental corruption.
+ You can also use a hmac algorithm (for example
+ "hmac(sha256):0123456789abcdef"), in this mode it will provide
+ cryptographic authentication of the data without encryption.
+
+ When this argument is not used, the integrity tags are accepted
+ from an upper layer target, such as dm-crypt. The upper layer
+ target should check the validity of the integrity tags.
+
+recalculate
+ Recalculate the integrity tags automatically. It is only valid
+ when using internal hash.
+
+journal_crypt:algorithm(:key) (the key is optional)
+ Encrypt the journal using given algorithm to make sure that the
+ attacker can't read the journal. You can use a block cipher here
+ (such as "cbc(aes)") or a stream cipher (for example "chacha20"
+ or "ctr(aes)").
+
+ The journal contains history of last writes to the block device,
+ an attacker reading the journal could see the last sector numbers
+ that were written. From the sector numbers, the attacker can infer
+ the size of files that were written. To protect against this
+ situation, you can encrypt the journal.
+
+journal_mac:algorithm(:key) (the key is optional)
+ Protect sector numbers in the journal from accidental or malicious
+ modification. To protect against accidental modification, use a
+ crc algorithm, to protect against malicious modification, use a
+ hmac algorithm with a key.
+
+ This option is not needed when using internal-hash because in this
+ mode, the integrity of journal entries is checked when replaying
+ the journal. Thus, modified sector number would be detected at
+ this stage.
+
+block_size:number
+ The size of a data block in bytes. The larger the block size the
+ less overhead there is for per-block integrity metadata.
+ Supported values are 512, 1024, 2048 and 4096 bytes. If not
+ specified the default block size is 512 bytes.
+
+sectors_per_bit:number
+ In the bitmap mode, this parameter specifies the number of
+ 512-byte sectors that corresponds to one bitmap bit.
+
+bitmap_flush_interval:number
+ The bitmap flush interval in milliseconds. The metadata buffers
+ are synchronized when this interval expires.
+
+allow_discards
+ Allow block discard requests (a.k.a. TRIM) for the integrity device.
+ Discards are only allowed to devices using internal hash.
+
+fix_padding
+ Use a smaller padding of the tag area that is more
+ space-efficient. If this option is not present, large padding is
+ used - that is for compatibility with older kernels.
+
+fix_hmac
+ Improve security of internal_hash and journal_mac:
+
+ - the section number is mixed to the mac, so that an attacker can't
+ copy sectors from one journal section to another journal section
+ - the superblock is protected by journal_mac
+ - a 16-byte salt stored in the superblock is mixed to the mac, so
+ that the attacker can't detect that two disks have the same hmac
+ key and also to disallow the attacker to move sectors from one
+ disk to another
+
+legacy_recalculate
+ Allow recalculating of volumes with HMAC keys. This is disabled by
+ default for security reasons - an attacker could modify the volume,
+ set recalc_sector to zero, and the kernel would not detect the
+ modification.
+
+The journal mode (D/J), buffer_sectors, journal_watermark, commit_time and
+allow_discards can be changed when reloading the target (load an inactive
+table and swap the tables with suspend and resume). The other arguments
+should not be changed when reloading the target because the layout of disk
+data depend on them and the reloaded target would be non-functional.
+
+
+Status line:
+
+1. the number of integrity mismatches
+2. provided data sectors - that is the number of sectors that the user
+ could use
+3. the current recalculating position (or '-' if we didn't recalculate)
+
+
+The layout of the formatted block device:
+
+* reserved sectors
+ (they are not used by this target, they can be used for
+ storing LUKS metadata or for other purpose), the size of the reserved
+ area is specified in the target arguments
+
+* superblock (4kiB)
+ * magic string - identifies that the device was formatted
+ * version
+ * log2(interleave sectors)
+ * integrity tag size
+ * the number of journal sections
+ * provided data sectors - the number of sectors that this target
+ provides (i.e. the size of the device minus the size of all
+ metadata and padding). The user of this target should not send
+ bios that access data beyond the "provided data sectors" limit.
+ * flags
+ SB_FLAG_HAVE_JOURNAL_MAC
+ - a flag is set if journal_mac is used
+ SB_FLAG_RECALCULATING
+ - recalculating is in progress
+ SB_FLAG_DIRTY_BITMAP
+ - journal area contains the bitmap of dirty
+ blocks
+ * log2(sectors per block)
+ * a position where recalculating finished
+* journal
+ The journal is divided into sections, each section contains:
+
+ * metadata area (4kiB), it contains journal entries
+
+ - every journal entry contains:
+
+ * logical sector (specifies where the data and tag should
+ be written)
+ * last 8 bytes of data
+ * integrity tag (the size is specified in the superblock)
+
+ - every metadata sector ends with
+
+ * mac (8-bytes), all the macs in 8 metadata sectors form a
+ 64-byte value. It is used to store hmac of sector
+ numbers in the journal section, to protect against a
+ possibility that the attacker tampers with sector
+ numbers in the journal.
+ * commit id
+
+ * data area (the size is variable; it depends on how many journal
+ entries fit into the metadata area)
+
+ - every sector in the data area contains:
+
+ * data (504 bytes of data, the last 8 bytes are stored in
+ the journal entry)
+ * commit id
+
+ To test if the whole journal section was written correctly, every
+ 512-byte sector of the journal ends with 8-byte commit id. If the
+ commit id matches on all sectors in a journal section, then it is
+ assumed that the section was written correctly. If the commit id
+ doesn't match, the section was written partially and it should not
+ be replayed.
+
+* one or more runs of interleaved tags and data.
+ Each run contains:
+
+ * tag area - it contains integrity tags. There is one tag for each
+ sector in the data area
+ * data area - it contains data sectors. The number of data sectors
+ in one run must be a power of two. log2 of this value is stored
+ in the superblock.