mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-11-01 08:58:07 +00:00
f1a880a93b
If the hash tree itself is sufficiently corrupt in addition to data blocks,
it's possible for error correction to end up in a deep recursive loop,
which eventually causes a kernel panic. This change limits the
recursion to a reasonable level during a single I/O operation.
Fixes: a739ff3f54 ("dm verity: add support for forward error correction")
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Cc: stable@vger.kernel.org # v4.5+
156 lines
4.4 KiB
C
156 lines
4.4 KiB
C
/*
|
|
* Copyright (C) 2015 Google, Inc.
|
|
*
|
|
* Author: Sami Tolvanen <samitolvanen@google.com>
|
|
*
|
|
* This program is free software; you can redistribute it and/or modify it
|
|
* under the terms of the GNU General Public License as published by the Free
|
|
* Software Foundation; either version 2 of the License, or (at your option)
|
|
* any later version.
|
|
*/
|
|
|
|
#ifndef DM_VERITY_FEC_H
|
|
#define DM_VERITY_FEC_H
|
|
|
|
#include "dm-verity.h"
|
|
#include <linux/rslib.h>
|
|
|
|
/* Reed-Solomon(M, N) parameters */
|
|
#define DM_VERITY_FEC_RSM 255
|
|
#define DM_VERITY_FEC_MAX_RSN 253
|
|
#define DM_VERITY_FEC_MIN_RSN 231 /* ~10% space overhead */
|
|
|
|
/* buffers for deinterleaving and decoding */
|
|
#define DM_VERITY_FEC_BUF_PREALLOC 1 /* buffers to preallocate */
|
|
#define DM_VERITY_FEC_BUF_RS_BITS 4 /* 1 << RS blocks per buffer */
|
|
/* we need buffers for at most 1 << block size RS blocks */
|
|
#define DM_VERITY_FEC_BUF_MAX \
|
|
(1 << (PAGE_SHIFT - DM_VERITY_FEC_BUF_RS_BITS))
|
|
|
|
/* maximum recursion level for verity_fec_decode */
|
|
#define DM_VERITY_FEC_MAX_RECURSION 4
|
|
|
|
#define DM_VERITY_OPT_FEC_DEV "use_fec_from_device"
|
|
#define DM_VERITY_OPT_FEC_BLOCKS "fec_blocks"
|
|
#define DM_VERITY_OPT_FEC_START "fec_start"
|
|
#define DM_VERITY_OPT_FEC_ROOTS "fec_roots"
|
|
|
|
/* configuration */
|
|
struct dm_verity_fec {
|
|
struct dm_dev *dev; /* parity data device */
|
|
struct dm_bufio_client *data_bufio; /* for data dev access */
|
|
struct dm_bufio_client *bufio; /* for parity data access */
|
|
sector_t start; /* parity data start in blocks */
|
|
sector_t blocks; /* number of blocks covered */
|
|
sector_t rounds; /* number of interleaving rounds */
|
|
sector_t hash_blocks; /* blocks covered after v->hash_start */
|
|
unsigned char roots; /* number of parity bytes, M-N of RS(M, N) */
|
|
unsigned char rsn; /* N of RS(M, N) */
|
|
mempool_t *rs_pool; /* mempool for fio->rs */
|
|
mempool_t *prealloc_pool; /* mempool for preallocated buffers */
|
|
mempool_t *extra_pool; /* mempool for extra buffers */
|
|
mempool_t *output_pool; /* mempool for output */
|
|
struct kmem_cache *cache; /* cache for buffers */
|
|
};
|
|
|
|
/* per-bio data */
|
|
struct dm_verity_fec_io {
|
|
struct rs_control *rs; /* Reed-Solomon state */
|
|
int erasures[DM_VERITY_FEC_MAX_RSN]; /* erasures for decode_rs8 */
|
|
u8 *bufs[DM_VERITY_FEC_BUF_MAX]; /* bufs for deinterleaving */
|
|
unsigned nbufs; /* number of buffers allocated */
|
|
u8 *output; /* buffer for corrected output */
|
|
size_t output_pos;
|
|
unsigned level; /* recursion level */
|
|
};
|
|
|
|
#ifdef CONFIG_DM_VERITY_FEC
|
|
|
|
/* each feature parameter requires a value */
|
|
#define DM_VERITY_OPTS_FEC 8
|
|
|
|
extern bool verity_fec_is_enabled(struct dm_verity *v);
|
|
|
|
extern int verity_fec_decode(struct dm_verity *v, struct dm_verity_io *io,
|
|
enum verity_block_type type, sector_t block,
|
|
u8 *dest, struct bvec_iter *iter);
|
|
|
|
extern unsigned verity_fec_status_table(struct dm_verity *v, unsigned sz,
|
|
char *result, unsigned maxlen);
|
|
|
|
extern void verity_fec_finish_io(struct dm_verity_io *io);
|
|
extern void verity_fec_init_io(struct dm_verity_io *io);
|
|
|
|
extern bool verity_is_fec_opt_arg(const char *arg_name);
|
|
extern int verity_fec_parse_opt_args(struct dm_arg_set *as,
|
|
struct dm_verity *v, unsigned *argc,
|
|
const char *arg_name);
|
|
|
|
extern void verity_fec_dtr(struct dm_verity *v);
|
|
|
|
extern int verity_fec_ctr_alloc(struct dm_verity *v);
|
|
extern int verity_fec_ctr(struct dm_verity *v);
|
|
|
|
#else /* !CONFIG_DM_VERITY_FEC */
|
|
|
|
#define DM_VERITY_OPTS_FEC 0
|
|
|
|
static inline bool verity_fec_is_enabled(struct dm_verity *v)
|
|
{
|
|
return false;
|
|
}
|
|
|
|
static inline int verity_fec_decode(struct dm_verity *v,
|
|
struct dm_verity_io *io,
|
|
enum verity_block_type type,
|
|
sector_t block, u8 *dest,
|
|
struct bvec_iter *iter)
|
|
{
|
|
return -EOPNOTSUPP;
|
|
}
|
|
|
|
static inline unsigned verity_fec_status_table(struct dm_verity *v,
|
|
unsigned sz, char *result,
|
|
unsigned maxlen)
|
|
{
|
|
return sz;
|
|
}
|
|
|
|
static inline void verity_fec_finish_io(struct dm_verity_io *io)
|
|
{
|
|
}
|
|
|
|
static inline void verity_fec_init_io(struct dm_verity_io *io)
|
|
{
|
|
}
|
|
|
|
static inline bool verity_is_fec_opt_arg(const char *arg_name)
|
|
{
|
|
return false;
|
|
}
|
|
|
|
static inline int verity_fec_parse_opt_args(struct dm_arg_set *as,
|
|
struct dm_verity *v,
|
|
unsigned *argc,
|
|
const char *arg_name)
|
|
{
|
|
return -EINVAL;
|
|
}
|
|
|
|
static inline void verity_fec_dtr(struct dm_verity *v)
|
|
{
|
|
}
|
|
|
|
static inline int verity_fec_ctr_alloc(struct dm_verity *v)
|
|
{
|
|
return 0;
|
|
}
|
|
|
|
static inline int verity_fec_ctr(struct dm_verity *v)
|
|
{
|
|
return 0;
|
|
}
|
|
|
|
#endif /* CONFIG_DM_VERITY_FEC */
|
|
|
|
#endif /* DM_VERITY_FEC_H */
|