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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 /fs/verity/verify.c
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 'fs/verity/verify.c')
-rw-r--r--fs/verity/verify.c409
1 files changed, 409 insertions, 0 deletions
diff --git a/fs/verity/verify.c b/fs/verity/verify.c
new file mode 100644
index 000000000..f50e3b5b5
--- /dev/null
+++ b/fs/verity/verify.c
@@ -0,0 +1,409 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Data verification functions, i.e. hooks for ->readahead()
+ *
+ * Copyright 2019 Google LLC
+ */
+
+#include "fsverity_private.h"
+
+#include <crypto/hash.h>
+#include <linux/bio.h>
+
+static struct workqueue_struct *fsverity_read_workqueue;
+
+static inline int cmp_hashes(const struct fsverity_info *vi,
+ const u8 *want_hash, const u8 *real_hash,
+ u64 data_pos, int level)
+{
+ const unsigned int hsize = vi->tree_params.digest_size;
+
+ if (memcmp(want_hash, real_hash, hsize) == 0)
+ return 0;
+
+ fsverity_err(vi->inode,
+ "FILE CORRUPTED! pos=%llu, level=%d, want_hash=%s:%*phN, real_hash=%s:%*phN",
+ data_pos, level,
+ vi->tree_params.hash_alg->name, hsize, want_hash,
+ vi->tree_params.hash_alg->name, hsize, real_hash);
+ return -EBADMSG;
+}
+
+static bool data_is_zeroed(struct inode *inode, struct page *page,
+ unsigned int len, unsigned int offset)
+{
+ void *virt = kmap_local_page(page);
+
+ if (memchr_inv(virt + offset, 0, len)) {
+ kunmap_local(virt);
+ fsverity_err(inode,
+ "FILE CORRUPTED! Data past EOF is not zeroed");
+ return false;
+ }
+ kunmap_local(virt);
+ return true;
+}
+
+/*
+ * Returns true if the hash block with index @hblock_idx in the tree, located in
+ * @hpage, has already been verified.
+ */
+static bool is_hash_block_verified(struct fsverity_info *vi, struct page *hpage,
+ unsigned long hblock_idx)
+{
+ bool verified;
+ unsigned int blocks_per_page;
+ unsigned int i;
+
+ /*
+ * When the Merkle tree block size and page size are the same, then the
+ * ->hash_block_verified bitmap isn't allocated, and we use PG_checked
+ * to directly indicate whether the page's block has been verified.
+ *
+ * Using PG_checked also guarantees that we re-verify hash pages that
+ * get evicted and re-instantiated from the backing storage, as new
+ * pages always start out with PG_checked cleared.
+ */
+ if (!vi->hash_block_verified)
+ return PageChecked(hpage);
+
+ /*
+ * When the Merkle tree block size and page size differ, we use a bitmap
+ * to indicate whether each hash block has been verified.
+ *
+ * However, we still need to ensure that hash pages that get evicted and
+ * re-instantiated from the backing storage are re-verified. To do
+ * this, we use PG_checked again, but now it doesn't really mean
+ * "checked". Instead, now it just serves as an indicator for whether
+ * the hash page is newly instantiated or not.
+ *
+ * The first thread that sees PG_checked=0 must clear the corresponding
+ * bitmap bits, then set PG_checked=1. This requires a spinlock. To
+ * avoid having to take this spinlock in the common case of
+ * PG_checked=1, we start with an opportunistic lockless read.
+ */
+ if (PageChecked(hpage)) {
+ /*
+ * A read memory barrier is needed here to give ACQUIRE
+ * semantics to the above PageChecked() test.
+ */
+ smp_rmb();
+ return test_bit(hblock_idx, vi->hash_block_verified);
+ }
+ spin_lock(&vi->hash_page_init_lock);
+ if (PageChecked(hpage)) {
+ verified = test_bit(hblock_idx, vi->hash_block_verified);
+ } else {
+ blocks_per_page = vi->tree_params.blocks_per_page;
+ hblock_idx = round_down(hblock_idx, blocks_per_page);
+ for (i = 0; i < blocks_per_page; i++)
+ clear_bit(hblock_idx + i, vi->hash_block_verified);
+ /*
+ * A write memory barrier is needed here to give RELEASE
+ * semantics to the below SetPageChecked() operation.
+ */
+ smp_wmb();
+ SetPageChecked(hpage);
+ verified = false;
+ }
+ spin_unlock(&vi->hash_page_init_lock);
+ return verified;
+}
+
+/*
+ * Verify a single data block against the file's Merkle tree.
+ *
+ * In principle, we need to verify the entire path to the root node. However,
+ * for efficiency the filesystem may cache the hash blocks. Therefore we need
+ * only ascend the tree until an already-verified hash block is seen, and then
+ * verify the path to that block.
+ *
+ * Return: %true if the data block is valid, else %false.
+ */
+static bool
+verify_data_block(struct inode *inode, struct fsverity_info *vi,
+ struct ahash_request *req, struct page *data_page,
+ u64 data_pos, unsigned int dblock_offset_in_page,
+ unsigned long max_ra_pages)
+{
+ const struct merkle_tree_params *params = &vi->tree_params;
+ const unsigned int hsize = params->digest_size;
+ int level;
+ u8 _want_hash[FS_VERITY_MAX_DIGEST_SIZE];
+ const u8 *want_hash;
+ u8 real_hash[FS_VERITY_MAX_DIGEST_SIZE];
+ /* The hash blocks that are traversed, indexed by level */
+ struct {
+ /* Page containing the hash block */
+ struct page *page;
+ /* Index of the hash block in the tree overall */
+ unsigned long index;
+ /* Byte offset of the hash block within @page */
+ unsigned int offset_in_page;
+ /* Byte offset of the wanted hash within @page */
+ unsigned int hoffset;
+ } hblocks[FS_VERITY_MAX_LEVELS];
+ /*
+ * The index of the previous level's block within that level; also the
+ * index of that block's hash within the current level.
+ */
+ u64 hidx = data_pos >> params->log_blocksize;
+ int err;
+
+ if (unlikely(data_pos >= inode->i_size)) {
+ /*
+ * This can happen in the data page spanning EOF when the Merkle
+ * tree block size is less than the page size. The Merkle tree
+ * doesn't cover data blocks fully past EOF. But the entire
+ * page spanning EOF can be visible to userspace via a mmap, and
+ * any part past EOF should be all zeroes. Therefore, we need
+ * to verify that any data blocks fully past EOF are all zeroes.
+ */
+ return data_is_zeroed(inode, data_page, params->block_size,
+ dblock_offset_in_page);
+ }
+
+ /*
+ * Starting at the leaf level, ascend the tree saving hash blocks along
+ * the way until we find a hash block that has already been verified, or
+ * until we reach the root.
+ */
+ for (level = 0; level < params->num_levels; level++) {
+ unsigned long next_hidx;
+ unsigned long hblock_idx;
+ pgoff_t hpage_idx;
+ unsigned int hblock_offset_in_page;
+ unsigned int hoffset;
+ struct page *hpage;
+
+ /*
+ * The index of the block in the current level; also the index
+ * of that block's hash within the next level.
+ */
+ next_hidx = hidx >> params->log_arity;
+
+ /* Index of the hash block in the tree overall */
+ hblock_idx = params->level_start[level] + next_hidx;
+
+ /* Index of the hash page in the tree overall */
+ hpage_idx = hblock_idx >> params->log_blocks_per_page;
+
+ /* Byte offset of the hash block within the page */
+ hblock_offset_in_page =
+ (hblock_idx << params->log_blocksize) & ~PAGE_MASK;
+
+ /* Byte offset of the hash within the page */
+ hoffset = hblock_offset_in_page +
+ ((hidx << params->log_digestsize) &
+ (params->block_size - 1));
+
+ hpage = inode->i_sb->s_vop->read_merkle_tree_page(inode,
+ hpage_idx, level == 0 ? min(max_ra_pages,
+ params->tree_pages - hpage_idx) : 0);
+ if (IS_ERR(hpage)) {
+ err = PTR_ERR(hpage);
+ fsverity_err(inode,
+ "Error %d reading Merkle tree page %lu",
+ err, hpage_idx);
+ goto out;
+ }
+ if (is_hash_block_verified(vi, hpage, hblock_idx)) {
+ memcpy_from_page(_want_hash, hpage, hoffset, hsize);
+ want_hash = _want_hash;
+ put_page(hpage);
+ goto descend;
+ }
+ hblocks[level].page = hpage;
+ hblocks[level].index = hblock_idx;
+ hblocks[level].offset_in_page = hblock_offset_in_page;
+ hblocks[level].hoffset = hoffset;
+ hidx = next_hidx;
+ }
+
+ want_hash = vi->root_hash;
+descend:
+ /* Descend the tree verifying hash blocks. */
+ for (; level > 0; level--) {
+ struct page *hpage = hblocks[level - 1].page;
+ unsigned long hblock_idx = hblocks[level - 1].index;
+ unsigned int hblock_offset_in_page =
+ hblocks[level - 1].offset_in_page;
+ unsigned int hoffset = hblocks[level - 1].hoffset;
+
+ err = fsverity_hash_block(params, inode, req, hpage,
+ hblock_offset_in_page, real_hash);
+ if (err)
+ goto out;
+ err = cmp_hashes(vi, want_hash, real_hash, data_pos, level - 1);
+ if (err)
+ goto out;
+ /*
+ * Mark the hash block as verified. This must be atomic and
+ * idempotent, as the same hash block might be verified by
+ * multiple threads concurrently.
+ */
+ if (vi->hash_block_verified)
+ set_bit(hblock_idx, vi->hash_block_verified);
+ else
+ SetPageChecked(hpage);
+ memcpy_from_page(_want_hash, hpage, hoffset, hsize);
+ want_hash = _want_hash;
+ put_page(hpage);
+ }
+
+ /* Finally, verify the data block. */
+ err = fsverity_hash_block(params, inode, req, data_page,
+ dblock_offset_in_page, real_hash);
+ if (err)
+ goto out;
+ err = cmp_hashes(vi, want_hash, real_hash, data_pos, -1);
+out:
+ for (; level > 0; level--)
+ put_page(hblocks[level - 1].page);
+
+ return err == 0;
+}
+
+static bool
+verify_data_blocks(struct inode *inode, struct fsverity_info *vi,
+ struct ahash_request *req, struct folio *data_folio,
+ size_t len, size_t offset, unsigned long max_ra_pages)
+{
+ const unsigned int block_size = vi->tree_params.block_size;
+ u64 pos = (u64)data_folio->index << PAGE_SHIFT;
+
+ if (WARN_ON_ONCE(len <= 0 || !IS_ALIGNED(len | offset, block_size)))
+ return false;
+ if (WARN_ON_ONCE(!folio_test_locked(data_folio) ||
+ folio_test_uptodate(data_folio)))
+ return false;
+ do {
+ struct page *data_page =
+ folio_page(data_folio, offset >> PAGE_SHIFT);
+
+ if (!verify_data_block(inode, vi, req, data_page, pos + offset,
+ offset & ~PAGE_MASK, max_ra_pages))
+ return false;
+ offset += block_size;
+ len -= block_size;
+ } while (len);
+ return true;
+}
+
+/**
+ * fsverity_verify_blocks() - verify data in a folio
+ * @folio: the folio containing the data to verify
+ * @len: the length of the data to verify in the folio
+ * @offset: the offset of the data to verify in the folio
+ *
+ * Verify data that has just been read from a verity file. The data must be
+ * located in a pagecache folio that is still locked and not yet uptodate. The
+ * length and offset of the data must be Merkle tree block size aligned.
+ *
+ * Return: %true if the data is valid, else %false.
+ */
+bool fsverity_verify_blocks(struct folio *folio, size_t len, size_t offset)
+{
+ struct inode *inode = folio->mapping->host;
+ struct fsverity_info *vi = inode->i_verity_info;
+ struct ahash_request *req;
+ bool valid;
+
+ /* This allocation never fails, since it's mempool-backed. */
+ req = fsverity_alloc_hash_request(vi->tree_params.hash_alg, GFP_NOFS);
+
+ valid = verify_data_blocks(inode, vi, req, folio, len, offset, 0);
+
+ fsverity_free_hash_request(vi->tree_params.hash_alg, req);
+
+ return valid;
+}
+EXPORT_SYMBOL_GPL(fsverity_verify_blocks);
+
+#ifdef CONFIG_BLOCK
+/**
+ * fsverity_verify_bio() - verify a 'read' bio that has just completed
+ * @bio: the bio to verify
+ *
+ * Verify the bio's data against the file's Merkle tree. All bio data segments
+ * must be aligned to the file's Merkle tree block size. If any data fails
+ * verification, then bio->bi_status is set to an error status.
+ *
+ * This is a helper function for use by the ->readahead() method of filesystems
+ * that issue bios to read data directly into the page cache. Filesystems that
+ * populate the page cache without issuing bios (e.g. non block-based
+ * filesystems) must instead call fsverity_verify_page() directly on each page.
+ * All filesystems must also call fsverity_verify_page() on holes.
+ */
+void fsverity_verify_bio(struct bio *bio)
+{
+ struct inode *inode = bio_first_page_all(bio)->mapping->host;
+ struct fsverity_info *vi = inode->i_verity_info;
+ struct ahash_request *req;
+ struct folio_iter fi;
+ unsigned long max_ra_pages = 0;
+
+ /* This allocation never fails, since it's mempool-backed. */
+ req = fsverity_alloc_hash_request(vi->tree_params.hash_alg, GFP_NOFS);
+
+ if (bio->bi_opf & REQ_RAHEAD) {
+ /*
+ * If this bio is for data readahead, then we also do readahead
+ * of the first (largest) level of the Merkle tree. Namely,
+ * when a Merkle tree page is read, we also try to piggy-back on
+ * some additional pages -- up to 1/4 the number of data pages.
+ *
+ * This improves sequential read performance, as it greatly
+ * reduces the number of I/O requests made to the Merkle tree.
+ */
+ max_ra_pages = bio->bi_iter.bi_size >> (PAGE_SHIFT + 2);
+ }
+
+ bio_for_each_folio_all(fi, bio) {
+ if (!verify_data_blocks(inode, vi, req, fi.folio, fi.length,
+ fi.offset, max_ra_pages)) {
+ bio->bi_status = BLK_STS_IOERR;
+ break;
+ }
+ }
+
+ fsverity_free_hash_request(vi->tree_params.hash_alg, req);
+}
+EXPORT_SYMBOL_GPL(fsverity_verify_bio);
+#endif /* CONFIG_BLOCK */
+
+/**
+ * fsverity_enqueue_verify_work() - enqueue work on the fs-verity workqueue
+ * @work: the work to enqueue
+ *
+ * Enqueue verification work for asynchronous processing.
+ */
+void fsverity_enqueue_verify_work(struct work_struct *work)
+{
+ queue_work(fsverity_read_workqueue, work);
+}
+EXPORT_SYMBOL_GPL(fsverity_enqueue_verify_work);
+
+int __init fsverity_init_workqueue(void)
+{
+ /*
+ * Use an unbound workqueue to allow bios to be verified in parallel
+ * even when they happen to complete on the same CPU. This sacrifices
+ * locality, but it's worthwhile since hashing is CPU-intensive.
+ *
+ * Also use a high-priority workqueue to prioritize verification work,
+ * which blocks reads from completing, over regular application tasks.
+ */
+ fsverity_read_workqueue = alloc_workqueue("fsverity_read_queue",
+ WQ_UNBOUND | WQ_HIGHPRI,
+ num_online_cpus());
+ if (!fsverity_read_workqueue)
+ return -ENOMEM;
+ return 0;
+}
+
+void __init fsverity_exit_workqueue(void)
+{
+ destroy_workqueue(fsverity_read_workqueue);
+ fsverity_read_workqueue = NULL;
+}