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cf715f4b7e
dm-verity needs to access data blocks by virtual address in three different cases (zeroization, recheck, and forward error correction), and one more case (shash support) is coming. Since it's guaranteed that dm-verity data blocks never cross pages, and kmap_local_page and kunmap_local are no-ops on modern platforms anyway, just unconditionally "map" every data block's page and work with the virtual buffer directly. This simplifies the code and eliminates unnecessary overhead. Reviewed-by: Sami Tolvanen <samitolvanen@google.com> Acked-by: Ard Biesheuvel <ardb@kernel.org> Signed-off-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
152 lines
4.2 KiB
C
152 lines
4.2 KiB
C
/* SPDX-License-Identifier: GPL-2.0-or-later */
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/*
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* Copyright (C) 2015 Google, Inc.
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*
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* Author: Sami Tolvanen <samitolvanen@google.com>
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*/
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#ifndef DM_VERITY_FEC_H
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#define DM_VERITY_FEC_H
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#include "dm-verity.h"
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#include <linux/rslib.h>
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/* Reed-Solomon(M, N) parameters */
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#define DM_VERITY_FEC_RSM 255
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#define DM_VERITY_FEC_MAX_RSN 253
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#define DM_VERITY_FEC_MIN_RSN 231 /* ~10% space overhead */
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/* buffers for deinterleaving and decoding */
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#define DM_VERITY_FEC_BUF_PREALLOC 1 /* buffers to preallocate */
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#define DM_VERITY_FEC_BUF_RS_BITS 4 /* 1 << RS blocks per buffer */
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/* we need buffers for at most 1 << block size RS blocks */
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#define DM_VERITY_FEC_BUF_MAX \
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(1 << (PAGE_SHIFT - DM_VERITY_FEC_BUF_RS_BITS))
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/* maximum recursion level for verity_fec_decode */
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#define DM_VERITY_FEC_MAX_RECURSION 4
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#define DM_VERITY_OPT_FEC_DEV "use_fec_from_device"
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#define DM_VERITY_OPT_FEC_BLOCKS "fec_blocks"
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#define DM_VERITY_OPT_FEC_START "fec_start"
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#define DM_VERITY_OPT_FEC_ROOTS "fec_roots"
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/* configuration */
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struct dm_verity_fec {
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struct dm_dev *dev; /* parity data device */
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struct dm_bufio_client *data_bufio; /* for data dev access */
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struct dm_bufio_client *bufio; /* for parity data access */
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size_t io_size; /* IO size for roots */
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sector_t start; /* parity data start in blocks */
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sector_t blocks; /* number of blocks covered */
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sector_t rounds; /* number of interleaving rounds */
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sector_t hash_blocks; /* blocks covered after v->hash_start */
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unsigned char roots; /* number of parity bytes, M-N of RS(M, N) */
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unsigned char rsn; /* N of RS(M, N) */
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mempool_t rs_pool; /* mempool for fio->rs */
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mempool_t prealloc_pool; /* mempool for preallocated buffers */
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mempool_t extra_pool; /* mempool for extra buffers */
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mempool_t output_pool; /* mempool for output */
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struct kmem_cache *cache; /* cache for buffers */
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};
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/* per-bio data */
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struct dm_verity_fec_io {
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struct rs_control *rs; /* Reed-Solomon state */
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int erasures[DM_VERITY_FEC_MAX_RSN]; /* erasures for decode_rs8 */
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u8 *bufs[DM_VERITY_FEC_BUF_MAX]; /* bufs for deinterleaving */
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unsigned int nbufs; /* number of buffers allocated */
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u8 *output; /* buffer for corrected output */
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unsigned int level; /* recursion level */
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};
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#ifdef CONFIG_DM_VERITY_FEC
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/* each feature parameter requires a value */
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#define DM_VERITY_OPTS_FEC 8
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extern bool verity_fec_is_enabled(struct dm_verity *v);
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extern int verity_fec_decode(struct dm_verity *v, struct dm_verity_io *io,
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enum verity_block_type type, sector_t block,
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u8 *dest);
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extern unsigned int verity_fec_status_table(struct dm_verity *v, unsigned int sz,
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char *result, unsigned int maxlen);
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extern void verity_fec_finish_io(struct dm_verity_io *io);
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extern void verity_fec_init_io(struct dm_verity_io *io);
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extern bool verity_is_fec_opt_arg(const char *arg_name);
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extern int verity_fec_parse_opt_args(struct dm_arg_set *as,
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struct dm_verity *v, unsigned int *argc,
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const char *arg_name);
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extern void verity_fec_dtr(struct dm_verity *v);
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extern int verity_fec_ctr_alloc(struct dm_verity *v);
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extern int verity_fec_ctr(struct dm_verity *v);
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#else /* !CONFIG_DM_VERITY_FEC */
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#define DM_VERITY_OPTS_FEC 0
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static inline bool verity_fec_is_enabled(struct dm_verity *v)
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{
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return false;
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}
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static inline int verity_fec_decode(struct dm_verity *v,
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struct dm_verity_io *io,
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enum verity_block_type type,
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sector_t block, u8 *dest)
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{
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return -EOPNOTSUPP;
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}
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static inline unsigned int verity_fec_status_table(struct dm_verity *v,
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unsigned int sz, char *result,
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unsigned int maxlen)
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{
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return sz;
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}
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static inline void verity_fec_finish_io(struct dm_verity_io *io)
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{
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}
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static inline void verity_fec_init_io(struct dm_verity_io *io)
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{
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}
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static inline bool verity_is_fec_opt_arg(const char *arg_name)
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{
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return false;
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}
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static inline int verity_fec_parse_opt_args(struct dm_arg_set *as,
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struct dm_verity *v,
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unsigned int *argc,
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const char *arg_name)
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{
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return -EINVAL;
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}
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static inline void verity_fec_dtr(struct dm_verity *v)
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{
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}
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static inline int verity_fec_ctr_alloc(struct dm_verity *v)
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{
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return 0;
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}
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static inline int verity_fec_ctr(struct dm_verity *v)
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{
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return 0;
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}
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#endif /* CONFIG_DM_VERITY_FEC */
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#endif /* DM_VERITY_FEC_H */
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