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grub/grub-core/lib/xzembed/xz_dec_stream.c

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/* xz_dec_stream.c - .xz Stream decoder */
/*
* GRUB -- GRand Unified Bootloader
* Copyright (C) 2010 Free Software Foundation, Inc.
*
* GRUB 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 3 of the License, or
* (at your option) any later version.
*
* GRUB is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with GRUB. If not, see <http://www.gnu.org/licenses/>.
*/
/*
* This file is based on code from XZ embedded project
* http://tukaani.org/xz/embedded.html
*/
#include "xz_config.h"
#include "xz_private.h"
#include "xz_stream.h"
#include <grub/crypto.h>
/* Hash used to validate the Index field */
struct xz_dec_hash {
vli_type unpadded;
vli_type uncompressed;
#ifndef GRUB_EMBED_DECOMPRESSOR
uint64_t *hash_context;
#endif
};
/* Enough for up to 512 bits. */
#define MAX_HASH_SIZE 64
struct xz_dec {
/* Position in dec_main() */
enum {
SEQ_STREAM_HEADER,
SEQ_BLOCK_START,
SEQ_BLOCK_HEADER,
SEQ_BLOCK_UNCOMPRESS,
SEQ_BLOCK_PADDING,
SEQ_BLOCK_CHECK,
SEQ_INDEX,
SEQ_INDEX_PADDING,
SEQ_INDEX_CRC32,
SEQ_STREAM_FOOTER
} sequence;
/* Position in variable-length integers and Check fields */
uint32_t pos;
/* Variable-length integer decoded by dec_vli() */
vli_type vli;
/* Saved in_pos and out_pos */
size_t in_start;
size_t out_start;
/* CRC32 value in Block or Index */
#ifndef GRUB_EMBED_DECOMPRESSOR
uint8_t hash_value[MAX_HASH_SIZE]; /* need for crc32_validate*/
#endif
int have_hash_value;
#ifndef GRUB_EMBED_DECOMPRESSOR
uint64_t *hash_context;
uint64_t *crc32_context;
#endif
/* Hash function calculated from uncompressed data */
#ifndef GRUB_EMBED_DECOMPRESSOR
const gcry_md_spec_t *hash;
const gcry_md_spec_t *crc32;
grub_uint8_t hash_id;
#endif
grub_size_t hash_size;
/* True if we are operating in single-call mode. */
bool single_call;
/*
* True if the next call to xz_dec_run() is allowed to return
* XZ_BUF_ERROR.
*/
bool allow_buf_error;
/* Information stored in Block Header */
struct {
/*
* Value stored in the Compressed Size field, or
* VLI_UNKNOWN if Compressed Size is not present.
*/
vli_type compressed;
/*
* Value stored in the Uncompressed Size field, or
* VLI_UNKNOWN if Uncompressed Size is not present.
*/
vli_type uncompressed;
/* Size of the Block Header field */
uint32_t size;
} block_header;
/* Information collected when decoding Blocks */
struct {
/* Observed compressed size of the current Block */
vli_type compressed;
/* Observed uncompressed size of the current Block */
vli_type uncompressed;
/* Number of Blocks decoded so far */
vli_type count;
/*
* Hash calculated from the Block sizes. This is used to
* validate the Index field.
*/
struct xz_dec_hash hash;
} block;
/* Variables needed when verifying the Index field */
struct {
/* Position in dec_index() */
enum {
SEQ_INDEX_COUNT,
SEQ_INDEX_UNPADDED,
SEQ_INDEX_UNCOMPRESSED
} sequence;
/* Size of the Index in bytes */
vli_type size;
/* Number of Records (matches block.count in valid files) */
vli_type count;
/*
* Hash calculated from the Records (matches block.hash in
* valid files).
*/
struct xz_dec_hash hash;
} index;
/*
* Temporary buffer needed to hold Stream Header, Block Header,
* and Stream Footer. The Block Header is the biggest (1 KiB)
* so we reserve space according to that. buf[] has to be aligned
* to a multiple of four bytes; the size_t variables before it
* should guarantee this.
*/
struct {
size_t pos;
size_t size;
uint8_t buf[1024];
} temp;
struct xz_dec_lzma2 *lzma2;
#ifdef XZ_DEC_BCJ
struct xz_dec_bcj *bcj;
bool bcj_active;
#endif
};
/*
* Fill s->temp by copying data starting from b->in[b->in_pos]. Caller
* must have set s->temp.pos to indicate how much data we are supposed
* to copy into s->temp.buf. Return true once s->temp.pos has reached
* s->temp.size.
*/
static bool fill_temp(struct xz_dec *s, struct xz_buf *b)
{
size_t copy_size = min_t(size_t,
b->in_size - b->in_pos, s->temp.size - s->temp.pos);
memcpy(s->temp.buf + s->temp.pos, b->in + b->in_pos, copy_size);
b->in_pos += copy_size;
s->temp.pos += copy_size;
if (s->temp.pos == s->temp.size) {
s->temp.pos = 0;
return true;
}
return false;
}
/* Decode a variable-length integer (little-endian base-128 encoding) */
static enum xz_ret dec_vli(struct xz_dec *s,
const uint8_t *in, size_t *in_pos, size_t in_size)
{
uint8_t b;
if (s->pos == 0)
s->vli = 0;
while (*in_pos < in_size) {
b = in[*in_pos];
++*in_pos;
s->vli |= (vli_type)(b & 0x7F) << s->pos;
if ((b & 0x80) == 0) {
/* Don't allow non-minimal encodings. */
if (b == 0 && s->pos != 0)
return XZ_DATA_ERROR;
s->pos = 0;
return XZ_STREAM_END;
}
s->pos += 7;
if (s->pos == 7 * VLI_BYTES_MAX)
return XZ_DATA_ERROR;
}
return XZ_OK;
}
/*
* Decode the Compressed Data field from a Block. Update and validate
* the observed compressed and uncompressed sizes of the Block so that
* they don't exceed the values possibly stored in the Block Header
* (validation assumes that no integer overflow occurs, since vli_type
* is normally uint64_t). Update the CRC32 if presence of the CRC32
* field was indicated in Stream Header.
*
* Once the decoding is finished, validate that the observed sizes match
* the sizes possibly stored in the Block Header. Update the hash and
* Block count, which are later used to validate the Index field.
*/
static enum xz_ret dec_block(struct xz_dec *s, struct xz_buf *b)
{
enum xz_ret ret;
s->in_start = b->in_pos;
s->out_start = b->out_pos;
#ifdef XZ_DEC_BCJ
if (s->bcj_active)
ret = xz_dec_bcj_run(s->bcj, s->lzma2, b);
else
#endif
ret = xz_dec_lzma2_run(s->lzma2, b);
s->block.compressed += b->in_pos - s->in_start;
s->block.uncompressed += b->out_pos - s->out_start;
/*
* There is no need to separately check for VLI_UNKNOWN, since
* the observed sizes are always smaller than VLI_UNKNOWN.
*/
if (s->block.compressed > s->block_header.compressed
|| s->block.uncompressed
> s->block_header.uncompressed)
return XZ_DATA_ERROR;
#ifndef GRUB_EMBED_DECOMPRESSOR
if (s->hash)
s->hash->write(s->hash_context,b->out + s->out_start,
b->out_pos - s->out_start);
if (s->crc32)
s->crc32->write(s->crc32_context,b->out + s->out_start,
b->out_pos - s->out_start);
#endif
if (ret == XZ_STREAM_END) {
if (s->block_header.compressed != VLI_UNKNOWN
&& s->block_header.compressed
!= s->block.compressed)
return XZ_DATA_ERROR;
if (s->block_header.uncompressed != VLI_UNKNOWN
&& s->block_header.uncompressed
!= s->block.uncompressed)
return XZ_DATA_ERROR;
s->block.hash.unpadded += s->block_header.size
+ s->block.compressed;
s->block.hash.unpadded += s->hash_size;
s->block.hash.uncompressed += s->block.uncompressed;
#ifndef GRUB_EMBED_DECOMPRESSOR
if (s->hash)
s->hash->write(s->block.hash.hash_context,
(const uint8_t *)&s->block.hash,
2 * sizeof(vli_type));
#endif
++s->block.count;
}
return ret;
}
/* Update the Index size and the CRC32 value. */
static void index_update(struct xz_dec *s, const struct xz_buf *b)
{
size_t in_used = b->in_pos - s->in_start;
s->index.size += in_used;
#ifndef GRUB_EMBED_DECOMPRESSOR
if (s->hash)
s->hash->write(s->hash_context,b->in + s->in_start, in_used);
if (s->crc32)
s->crc32->write(s->crc32_context,b->in + s->in_start, in_used);
#endif
}
/*
* Decode the Number of Records, Unpadded Size, and Uncompressed Size
* fields from the Index field. That is, Index Padding and CRC32 are not
* decoded by this function.
*
* This can return XZ_OK (more input needed), XZ_STREAM_END (everything
* successfully decoded), or XZ_DATA_ERROR (input is corrupt).
*/
static enum xz_ret dec_index(struct xz_dec *s, struct xz_buf *b)
{
enum xz_ret ret;
do {
ret = dec_vli(s, b->in, &b->in_pos, b->in_size);
if (ret != XZ_STREAM_END) {
index_update(s, b);
return ret;
}
switch (s->index.sequence) {
case SEQ_INDEX_COUNT:
s->index.count = s->vli;
/*
* Validate that the Number of Records field
* indicates the same number of Records as
* there were Blocks in the Stream.
*/
if (s->index.count != s->block.count)
return XZ_DATA_ERROR;
s->index.sequence = SEQ_INDEX_UNPADDED;
break;
case SEQ_INDEX_UNPADDED:
s->index.hash.unpadded += s->vli;
s->index.sequence = SEQ_INDEX_UNCOMPRESSED;
break;
case SEQ_INDEX_UNCOMPRESSED:
s->index.hash.uncompressed += s->vli;
#ifndef GRUB_EMBED_DECOMPRESSOR
if (s->hash)
s->hash->write(s->index.hash.hash_context,
(const uint8_t *)&s->index.hash, 2 * sizeof(vli_type));
#endif
--s->index.count;
s->index.sequence = SEQ_INDEX_UNPADDED;
break;
}
} while (s->index.count > 0);
return XZ_STREAM_END;
}
/*
* Validate that the next four input bytes match the value of s->crc32.
* s->pos must be zero when starting to validate the first byte.
*/
static enum xz_ret hash_validate(struct xz_dec *s, struct xz_buf *b,
int crc32)
{
#ifndef GRUB_EMBED_DECOMPRESSOR
const gcry_md_spec_t *hash = crc32 ? s->crc32 : s->hash;
void *hash_context = crc32 ? s->crc32_context
: s->hash_context;
if(!s->have_hash_value && hash
&& sizeof (s->hash_value) >= hash->mdlen)
{
hash->final(hash_context);
grub_memcpy (s->hash_value, hash->read(hash_context),
hash->mdlen);
s->have_hash_value = 1;
if (s->hash_id == 1 || crc32)
{
grub_uint8_t t;
t = s->hash_value[0];
s->hash_value[0] = s->hash_value[3];
s->hash_value[3] = t;
t = s->hash_value[1];
s->hash_value[1] = s->hash_value[2];
s->hash_value[2] = t;
}
}
#endif
if (b->in_pos == b->in_size)
return XZ_OK;
if (!crc32 && s->hash_size == 0)
s->pos += 8;
while (s->pos < (crc32 ? 32 : s->hash_size * 8)) {
if (b->in_pos == b->in_size)
return XZ_OK;
#ifndef GRUB_EMBED_DECOMPRESSOR
if (hash && s->hash_value[s->pos / 8] != b->in[b->in_pos])
return XZ_DATA_ERROR;
#endif
b->in_pos++;
s->pos += 8;
}
#ifndef GRUB_EMBED_DECOMPRESSOR
if (s->hash)
s->hash->init(s->hash_context);
if (s->crc32)
s->crc32->init(s->crc32_context);
#endif
s->have_hash_value = 0;
s->pos = 0;
return XZ_STREAM_END;
}
static const struct
{
const char *name;
grub_size_t size;
} hashes[] = {
[0x01] = { "CRC32", 4},
[0x04] = { "CRC64", 8},
[0x0A] = { "SHA256", 32},
};
/* Decode the Stream Header field (the first 12 bytes of the .xz Stream). */
static enum xz_ret dec_stream_header(struct xz_dec *s)
{
if (! memeq(s->temp.buf, HEADER_MAGIC, HEADER_MAGIC_SIZE))
return XZ_FORMAT_ERROR;
#ifndef GRUB_EMBED_DECOMPRESSOR
s->crc32 = grub_crypto_lookup_md_by_name ("CRC32");
if (s->crc32)
{
uint8_t readhash[4];
uint8_t computed_hash[4];
if(4 != s->crc32->mdlen)
return XZ_DATA_ERROR;
grub_crypto_hash (s->crc32, computed_hash,
s->temp.buf + HEADER_MAGIC_SIZE, 2);
readhash[0] = s->temp.buf[HEADER_MAGIC_SIZE + 5];
readhash[1] = s->temp.buf[HEADER_MAGIC_SIZE + 4];
readhash[2] = s->temp.buf[HEADER_MAGIC_SIZE + 3];
readhash[3] = s->temp.buf[HEADER_MAGIC_SIZE + 2];
if (grub_memcmp (readhash, computed_hash,
s->crc32->mdlen) != 0)
return XZ_DATA_ERROR;
}
#endif
#ifndef GRUB_EMBED_DECOMPRESSOR
/*
* Decode the Stream Flags field.
*/
if (s->temp.buf[HEADER_MAGIC_SIZE] != 0
|| s->temp.buf[HEADER_MAGIC_SIZE + 1] >= ARRAY_SIZE (hashes)
|| (hashes[s->temp.buf[HEADER_MAGIC_SIZE + 1]].name == 0
&& s->temp.buf[HEADER_MAGIC_SIZE + 1] != 0))
return XZ_OPTIONS_ERROR;
s->hash_id = s->temp.buf[HEADER_MAGIC_SIZE + 1];
if (s->crc32)
{
s->crc32_context = kmalloc(s->crc32->contextsize, GFP_KERNEL);
if (s->crc32_context == NULL)
return XZ_MEMLIMIT_ERROR;
s->crc32->init(s->crc32_context);
}
#endif
if (s->temp.buf[HEADER_MAGIC_SIZE + 1])
{
s->hash_size = hashes[s->temp.buf[HEADER_MAGIC_SIZE + 1]].size;
#ifndef GRUB_EMBED_DECOMPRESSOR
s->hash = grub_crypto_lookup_md_by_name (hashes[s->temp.buf[HEADER_MAGIC_SIZE + 1]].name);
if (s->hash)
{
if (s->hash->mdlen != s->hash_size)
return XZ_OPTIONS_ERROR;
s->hash_context = kmalloc(s->hash->contextsize, GFP_KERNEL);
if (s->hash_context == NULL)
{
kfree(s->crc32_context);
return XZ_MEMLIMIT_ERROR;
}
s->index.hash.hash_context = kmalloc(s->hash->contextsize,
GFP_KERNEL);
if (s->index.hash.hash_context == NULL)
{
kfree(s->hash_context);
kfree(s->crc32_context);
return XZ_MEMLIMIT_ERROR;
}
s->block.hash.hash_context = kmalloc(s->hash->contextsize, GFP_KERNEL);
if (s->block.hash.hash_context == NULL)
{
kfree(s->index.hash.hash_context);
kfree(s->hash_context);
kfree(s->crc32_context);
return XZ_MEMLIMIT_ERROR;
}
s->hash->init(s->hash_context);
s->hash->init(s->index.hash.hash_context);
s->hash->init(s->block.hash.hash_context);
}
#endif
}
else
{
#ifndef GRUB_EMBED_DECOMPRESSOR
s->hash = 0;
#endif
s->hash_size = 0;
}
s->have_hash_value = 0;
return XZ_OK;
}
/* Decode the Stream Footer field (the last 12 bytes of the .xz Stream) */
static enum xz_ret dec_stream_footer(struct xz_dec *s)
{
if (! memeq(s->temp.buf + 10, FOOTER_MAGIC, FOOTER_MAGIC_SIZE))
return XZ_DATA_ERROR;
#ifndef GRUB_EMBED_DECOMPRESSOR
if (s->crc32)
{
uint8_t readhash[4];
uint8_t computed_hash[4];
if (4 != s->crc32->mdlen)
return XZ_DATA_ERROR;
grub_crypto_hash (s->crc32, computed_hash,
s->temp.buf + 4, 6);
readhash[0] = s->temp.buf[3];
readhash[1] = s->temp.buf[2];
readhash[2] = s->temp.buf[1];
readhash[3] = s->temp.buf[0];
if(grub_memcmp (readhash, computed_hash,
s->crc32->mdlen) != 0)
return XZ_DATA_ERROR;
}
#endif
/*
* Validate Backward Size. Note that we never added the size of the
* Index CRC32 field to s->index.size, thus we use s->index.size / 4
* instead of s->index.size / 4 - 1.
*/
if ((s->index.size >> 2) != get_le32(s->temp.buf + 4))
return XZ_DATA_ERROR;
#ifndef GRUB_EMBED_DECOMPRESSOR
if (s->temp.buf[8] != 0 || s->temp.buf[9] != s->hash_id)
return XZ_DATA_ERROR;
#endif
/*
* Use XZ_STREAM_END instead of XZ_OK to be more convenient
* for the caller.
*/
return XZ_STREAM_END;
}
/* Decode the Block Header and initialize the filter chain. */
static enum xz_ret dec_block_header(struct xz_dec *s)
{
enum xz_ret ret;
/*
* Validate the CRC32. We know that the temp buffer is at least
* eight bytes so this is safe.
*/
s->temp.size -= 4;
#ifndef GRUB_EMBED_DECOMPRESSOR
if (s->crc32)
{
uint8_t readhash[4], computed_hash[4];
if(4 != s->crc32->mdlen)
return XZ_DATA_ERROR;
grub_crypto_hash (s->crc32, computed_hash,
s->temp.buf, s->temp.size);
readhash[3] = s->temp.buf[s->temp.size];
readhash[2] = s->temp.buf[s->temp.size + 1];
readhash[1] = s->temp.buf[s->temp.size + 2];
readhash[0] = s->temp.buf[s->temp.size + 3];
if(grub_memcmp (readhash, computed_hash,
s->crc32->mdlen) != 0)
return XZ_DATA_ERROR;
}
#endif
s->temp.pos = 2;
/*
* Catch unsupported Block Flags. We support only one or two filters
* in the chain, so we catch that with the same test.
*/
#ifdef XZ_DEC_BCJ
if (s->temp.buf[1] & 0x3E)
#else
if (s->temp.buf[1] & 0x3F)
#endif
return XZ_OPTIONS_ERROR;
/* Compressed Size */
if (s->temp.buf[1] & 0x40) {
if (dec_vli(s, s->temp.buf, &s->temp.pos, s->temp.size)
!= XZ_STREAM_END)
return XZ_DATA_ERROR;
s->block_header.compressed = s->vli;
} else {
s->block_header.compressed = VLI_UNKNOWN;
}
/* Uncompressed Size */
if (s->temp.buf[1] & 0x80) {
if (dec_vli(s, s->temp.buf, &s->temp.pos, s->temp.size)
!= XZ_STREAM_END)
return XZ_DATA_ERROR;
s->block_header.uncompressed = s->vli;
} else {
s->block_header.uncompressed = VLI_UNKNOWN;
}
#ifdef XZ_DEC_BCJ
/* If there are two filters, the first one must be a BCJ filter. */
s->bcj_active = s->temp.buf[1] & 0x01;
if (s->bcj_active) {
if (s->temp.size - s->temp.pos < 2)
return XZ_OPTIONS_ERROR;
ret = xz_dec_bcj_reset(s->bcj, s->temp.buf[s->temp.pos++]);
if (ret != XZ_OK)
return ret;
/*
* We don't support custom start offset,
* so Size of Properties must be zero.
*/
if (s->temp.buf[s->temp.pos++] != 0x00)
return XZ_OPTIONS_ERROR;
}
#endif
/* Valid Filter Flags always take at least two bytes. */
if (s->temp.size - s->temp.pos < 2)
return XZ_DATA_ERROR;
/* Filter ID = LZMA2 */
if (s->temp.buf[s->temp.pos++] != 0x21)
return XZ_OPTIONS_ERROR;
/* Size of Properties = 1-byte Filter Properties */
if (s->temp.buf[s->temp.pos++] != 0x01)
return XZ_OPTIONS_ERROR;
/* Filter Properties contains LZMA2 dictionary size. */
if (s->temp.size - s->temp.pos < 1)
return XZ_DATA_ERROR;
ret = xz_dec_lzma2_reset(s->lzma2, s->temp.buf[s->temp.pos++]);
if (ret != XZ_OK)
return ret;
/* The rest must be Header Padding. */
while (s->temp.pos < s->temp.size)
if (s->temp.buf[s->temp.pos++] != 0x00)
return XZ_OPTIONS_ERROR;
s->temp.pos = 0;
s->block.compressed = 0;
s->block.uncompressed = 0;
return XZ_OK;
}
static enum xz_ret dec_main(struct xz_dec *s, struct xz_buf *b)
{
enum xz_ret ret;
/*
* Store the start position for the case when we are in the middle
* of the Index field.
*/
s->in_start = b->in_pos;
while (true) {
switch (s->sequence) {
case SEQ_STREAM_HEADER:
/*
* Stream Header is copied to s->temp, and then
* decoded from there. This way if the caller
* gives us only little input at a time, we can
* still keep the Stream Header decoding code
* simple. Similar approach is used in many places
* in this file.
*/
if (!fill_temp(s, b))
return XZ_OK;
ret = dec_stream_header(s);
if (ret != XZ_OK)
return ret;
s->sequence = SEQ_BLOCK_START;
/* FALLTHROUGH */
case SEQ_BLOCK_START:
/* We need one byte of input to continue. */
if (b->in_pos == b->in_size)
return XZ_OK;
/* See if this is the beginning of the Index field. */
if (b->in[b->in_pos] == 0) {
s->in_start = b->in_pos++;
s->sequence = SEQ_INDEX;
break;
}
/*
* Calculate the size of the Block Header and
* prepare to decode it.
*/
s->block_header.size
= ((uint32_t)b->in[b->in_pos] + 1) * 4;
s->temp.size = s->block_header.size;
s->temp.pos = 0;
s->sequence = SEQ_BLOCK_HEADER;
/* FALLTHROUGH */
case SEQ_BLOCK_HEADER:
if (!fill_temp(s, b))
return XZ_OK;
ret = dec_block_header(s);
if (ret != XZ_OK)
return ret;
s->sequence = SEQ_BLOCK_UNCOMPRESS;
/* FALLTHROUGH */
case SEQ_BLOCK_UNCOMPRESS:
ret = dec_block(s, b);
if (ret != XZ_STREAM_END)
return ret;
s->sequence = SEQ_BLOCK_PADDING;
case SEQ_BLOCK_PADDING:
/*
* Size of Compressed Data + Block Padding
* must be a multiple of four. We don't need
* s->block.compressed for anything else
* anymore, so we use it here to test the size
* of the Block Padding field.
*/
while (s->block.compressed & 3) {
if (b->in_pos == b->in_size)
return XZ_OK;
if (b->in[b->in_pos++] != 0)
return XZ_DATA_ERROR;
++s->block.compressed;
}
s->sequence = SEQ_BLOCK_CHECK;
/* FALLTHROUGH */
case SEQ_BLOCK_CHECK:
ret = hash_validate(s, b, 0);
if (ret != XZ_STREAM_END)
return ret;
s->sequence = SEQ_BLOCK_START;
break;
case SEQ_INDEX:
ret = dec_index(s, b);
if (ret != XZ_STREAM_END)
return ret;
s->sequence = SEQ_INDEX_PADDING;
case SEQ_INDEX_PADDING:
while ((s->index.size + (b->in_pos - s->in_start))
& 3) {
if (b->in_pos == b->in_size) {
index_update(s, b);
return XZ_OK;
}
if (b->in[b->in_pos++] != 0)
return XZ_DATA_ERROR;
}
/* Finish the CRC32 value and Index size. */
index_update(s, b);
#ifndef GRUB_EMBED_DECOMPRESSOR
if (s->hash)
{
/* Compare the hashes to validate the Index field. */
s->hash->final(s->block.hash.hash_context);
s->hash->final(s->index.hash.hash_context);
if (s->block.hash.unpadded != s->index.hash.unpadded
|| s->block.hash.uncompressed != s->index.hash.uncompressed
|| grub_memcmp (s->hash->read(s->block.hash.hash_context),
s->hash->read(s->index.hash.hash_context),
s->hash->mdlen) != 0)
return XZ_DATA_ERROR;
}
#endif
s->sequence = SEQ_INDEX_CRC32;
/* FALLTHROUGH */
case SEQ_INDEX_CRC32:
ret = hash_validate(s, b, 1);
if (ret != XZ_STREAM_END)
return ret;
s->temp.size = STREAM_HEADER_SIZE;
s->sequence = SEQ_STREAM_FOOTER;
/* FALLTHROUGH */
case SEQ_STREAM_FOOTER:
if (!fill_temp(s, b))
return XZ_OK;
return dec_stream_footer(s);
}
}
/* Never reached */
}
/*
* xz_dec_run() is a wrapper for dec_main() to handle some special cases in
* multi-call and single-call decoding.
*
* In multi-call mode, we must return XZ_BUF_ERROR when it seems clear that we
* are not going to make any progress anymore. This is to prevent the caller
* from calling us infinitely when the input file is truncated or otherwise
* corrupt. Since zlib-style API allows that the caller fills the input buffer
* only when the decoder doesn't produce any new output, we have to be careful
* to avoid returning XZ_BUF_ERROR too easily: XZ_BUF_ERROR is returned only
* after the second consecutive call to xz_dec_run() that makes no progress.
*
* In single-call mode, if we couldn't decode everything and no error
* occurred, either the input is truncated or the output buffer is too small.
* Since we know that the last input byte never produces any output, we know
* that if all the input was consumed and decoding wasn't finished, the file
* must be corrupt. Otherwise the output buffer has to be too small or the
* file is corrupt in a way that decoding it produces too big output.
*
* If single-call decoding fails, we reset b->in_pos and b->out_pos back to
* their original values. This is because with some filter chains there won't
* be any valid uncompressed data in the output buffer unless the decoding
* actually succeeds (that's the price to pay of using the output buffer as
* the workspace).
*/
enum xz_ret xz_dec_run(struct xz_dec *s, struct xz_buf *b)
{
size_t in_start;
size_t out_start;
enum xz_ret ret;
if (s->single_call)
xz_dec_reset(s);
in_start = b->in_pos;
out_start = b->out_pos;
ret = dec_main(s, b);
if (s->single_call) {
if (ret == XZ_OK)
ret = b->in_pos == b->in_size
? XZ_DATA_ERROR : XZ_BUF_ERROR;
if (ret != XZ_STREAM_END) {
b->in_pos = in_start;
b->out_pos = out_start;
}
} else if (ret == XZ_OK && in_start == b->in_pos
&& out_start == b->out_pos) {
if (s->allow_buf_error)
ret = XZ_BUF_ERROR;
s->allow_buf_error = true;
} else {
s->allow_buf_error = false;
}
return ret;
}
#ifdef GRUB_EMBED_DECOMPRESSOR
struct xz_dec decoder;
#endif
struct xz_dec * xz_dec_init(uint32_t dict_max)
{
struct xz_dec *s;
#ifdef GRUB_EMBED_DECOMPRESSOR
s = &decoder;
#else
s = kmalloc(sizeof(*s), GFP_KERNEL);
if (s == NULL)
return NULL;
#endif
memset (s, 0, sizeof (*s));
s->single_call = dict_max == 0;
#ifdef XZ_DEC_BCJ
s->bcj = xz_dec_bcj_create(s->single_call);
if (s->bcj == NULL)
goto error_bcj;
#endif
s->lzma2 = xz_dec_lzma2_create(dict_max);
if (s->lzma2 == NULL)
goto error_lzma2;
xz_dec_reset(s);
return s;
error_lzma2:
#ifdef XZ_DEC_BCJ
xz_dec_bcj_end(s->bcj);
error_bcj:
#endif
#ifndef GRUB_EMBED_DECOMPRESSOR
kfree(s);
#endif
return NULL;
}
void xz_dec_reset(struct xz_dec *s)
{
s->sequence = SEQ_STREAM_HEADER;
s->allow_buf_error = false;
s->pos = 0;
{
#ifndef GRUB_EMBED_DECOMPRESSOR
uint64_t *t;
t = s->block.hash.hash_context;
#endif
memzero(&s->block, sizeof(s->block));
#ifndef GRUB_EMBED_DECOMPRESSOR
s->block.hash.hash_context = t;
t = s->index.hash.hash_context;
#endif
memzero(&s->index, sizeof(s->index));
#ifndef GRUB_EMBED_DECOMPRESSOR
s->index.hash.hash_context = t;
#endif
}
s->temp.pos = 0;
s->temp.size = STREAM_HEADER_SIZE;
#ifndef GRUB_EMBED_DECOMPRESSOR
if (s->hash)
{
s->hash->init(s->hash_context);
s->hash->init(s->index.hash.hash_context);
s->hash->init(s->block.hash.hash_context);
}
#endif
s->have_hash_value = 0;
}
void xz_dec_end(struct xz_dec *s)
{
if (s != NULL) {
xz_dec_lzma2_end(s->lzma2);
#ifndef GRUB_EMBED_DECOMPRESSOR
kfree(s->index.hash.hash_context);
kfree(s->block.hash.hash_context);
kfree(s->hash_context);
kfree(s->crc32_context);
#endif
#ifdef XZ_DEC_BCJ
xz_dec_bcj_end(s->bcj);
#endif
#ifndef GRUB_EMBED_DECOMPRESSOR
kfree(s);
#endif
}
}
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