// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Copyright 2021 Google LLC.
*/
#include <linux/init.h>
#include <linux/highmem.h>
#include <linux/kobject.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/sysfs.h>
#include <linux/vmalloc.h>
#include "internal.h"
static int module_extend_max_pages(struct load_info *info, unsigned int extent)
{
struct page **new_pages;
new_pages = kvmalloc_array(info->max_pages + extent,
sizeof(info->pages), GFP_KERNEL);
if (!new_pages)
return -ENOMEM;
memcpy(new_pages, info->pages, info->max_pages * sizeof(info->pages));
kvfree(info->pages);
info->pages = new_pages;
info->max_pages += extent;
return 0;
}
static struct page *module_get_next_page(struct load_info *info)
{
struct page *page;
int error;
if (info->max_pages == info->used_pages) {
error = module_extend_max_pages(info, info->used_pages);
if (error)
return ERR_PTR(error);
}
page = alloc_page(GFP_KERNEL | __GFP_HIGHMEM);
if (!page)
return ERR_PTR(-ENOMEM);
info->pages[info->used_pages++] = page;
return page;
}
#if defined(CONFIG_MODULE_COMPRESS_GZIP)
#include <linux/zlib.h>
#define MODULE_COMPRESSION gzip
#define MODULE_DECOMPRESS_FN module_gzip_decompress
/*
* Calculate length of the header which consists of signature, header
* flags, time stamp and operating system ID (10 bytes total), plus
* an optional filename.
*/
static size_t module_gzip_header_len(const u8 *buf, size_t size)
{
const u8 signature[] = { 0x1f, 0x8b, 0x08 };
size_t len = 10;
if (size < len || memcmp(buf, signature, sizeof(signature)))
return 0;
if (buf[3] & 0x08) {
do {
/*
* If we can't find the end of the file name we must
* be dealing with a corrupted file.
*/
if (len == size)
return 0;
} while (buf[len++] != '\0');
}
return len;
}
static ssize_t module_gzip_decompress(struct load_info *info,
const void *buf, size_t size)
{
struct z_stream_s s = { 0 };
size_t new_size = 0;
size_t gzip_hdr_len;
ssize_t retval;
int rc;
gzip_hdr_len = module_gzip_header_len(buf, size);
if (!gzip_hdr_len) {
pr_err("not a gzip compressed module\n");
return -EINVAL;
}
s.next_in = buf + gzip_hdr_len;
s.avail_in = size - gzip_hdr_len;
s.workspace = kvmalloc(zlib_inflate_workspacesize(), GFP_KERNEL);
if (!s.workspace)
return -ENOMEM;
rc = zlib_inflateInit2(&s, -MAX_WBITS);
if (rc != Z_OK) {
pr_err("failed to initialize decompressor: %d\n", rc);
retval = -EINVAL;
goto out;
}
do {
struct page *page = module_get_next_page(info);
if (IS_ERR(page)) {
retval = PTR_ERR(page);
goto out_inflate_end;
}
s.next_out = kmap_local_page(page);
s.avail_out = PAGE_SIZE;
rc = zlib_inflate(&s, 0);
kunmap_local(s.next_out);
new_size += PAGE_SIZE - s.avail_out;
} while (rc == Z_OK);
if (rc != Z_STREAM_END) {
pr_err("decompression failed with status %d\n", rc);
retval = -EINVAL;
goto out_inflate_end;
}
retval = new_size;
out_inflate_end:
zlib_inflateEnd(&s);
out:
kvfree(s.workspace);
return retval;
}
#elif defined(CONFIG_MODULE_COMPRESS_XZ)
#include <linux/xz.h>
#define MODULE_COMPRESSION xz
#define MODULE_DECOMPRESS_FN module_xz_decompress
static ssize_t module_xz_decompress(struct load_info *info,
const void *buf, size_t size)
{
static const u8 signature[] = { 0xfd, '7', 'z', 'X', 'Z', 0 };
struct xz_dec *xz_dec;
struct xz_buf xz_buf;
enum xz_ret xz_ret;
size_t new_size = 0;
ssize_t retval;
if (size < sizeof(signature) ||
memcmp(buf, signature, sizeof(signature))) {
pr_err("not an xz compressed module\n");
return -EINVAL;
}
xz_dec = xz_dec_init(XZ_DYNALLOC, (u32)-1);
if (!xz_dec)
return -ENOMEM;
xz_buf.in_size = size;
xz_buf.in = buf;
xz_buf.in_pos = 0;
do {
struct page *page = module_get_next_page(info);
if (IS_ERR(page)) {
retval = PTR_ERR(page);
goto out;
}
xz_buf.out = kmap_local_page(page);
xz_buf.out_pos = 0;
xz_buf.out_size = PAGE_SIZE;
xz_ret = xz_dec_run(xz_dec, &xz_buf);
kunmap_local(xz_buf.out);
new_size += xz_buf.out_pos;
} while (xz_buf.out_pos == PAGE_SIZE && xz_ret == XZ_OK);
if (xz_ret != XZ_STREAM_END) {
pr_err("decompression failed with status %d\n", xz_ret);
retval = -EINVAL;
goto out;
}
retval = new_size;
out:
xz_dec_end(xz_dec);
return retval;
}
#elif defined(CONFIG_MODULE_COMPRESS_ZSTD)
#include <linux/zstd.h>
#define MODULE_COMPRESSION zstd
#define MODULE_DECOMPRESS_FN module_zstd_decompress
static ssize_t module_zstd_decompress(struct load_info *info,
const void *buf, size_t size)
{
static const u8 signature[] = { 0x28, 0xb5, 0x2f, 0xfd };
ZSTD_outBuffer zstd_dec;
ZSTD_inBuffer zstd_buf;
zstd_frame_header header;
size_t wksp_size;
void *wksp = NULL;
ZSTD_DStream *dstream;
size_t ret;
size_t new_size = 0;
int retval;
if (size < sizeof(signature) ||
memcmp(buf, signature, sizeof(signature))) {
pr_err("not a zstd compressed module\n");
return -EINVAL;
}
zstd_buf.src = buf;
zstd_buf.pos = 0;
zstd_buf.size = size;
ret = zstd_get_frame_header(&header, zstd_buf.src, zstd_buf.size);
if (ret != 0) {
pr_err("ZSTD-compressed data has an incomplete frame header\n");
retval = -EINVAL;
goto out;
}
if (header.windowSize > (1 << ZSTD_WINDOWLOG_MAX)) {
pr_err("ZSTD-compressed data has too large a window size\n");
retval = -EINVAL;
goto out;
}
wksp_size = zstd_dstream_workspace_bound(header.windowSize);
wksp = kvmalloc(wksp_size, GFP_KERNEL);
if (!wksp) {
retval = -ENOMEM;
goto out;
}
dstream = zstd_init_dstream(header.windowSize, wksp, wksp_size);
if (!dstream) {
pr_err("Can't initialize ZSTD stream\n");
retval = -ENOMEM;
goto out;
}
do {
struct page *page = module_get_next_page(info);
if (IS_ERR(page)) {
retval = PTR_ERR(page);
goto out;
}
zstd_dec.dst = kmap_local_page(page);
zstd_dec.pos = 0;
zstd_dec.size = PAGE_SIZE;
ret = zstd_decompress_stream(dstream, &zstd_dec, &zstd_buf);
kunmap_local(zstd_dec.dst);
retval = zstd_get_error_code(ret);
if (retval)
break;
new_size += zstd_dec.pos;
} while (zstd_dec.pos == PAGE_SIZE && ret != 0);
if (retval) {
pr_err("ZSTD-decompression failed with status %d\n", retval);
retval = -EINVAL;
goto out;
}
retval = new_size;
out:
kvfree(wksp);
return retval;
}
#else
#error "Unexpected configuration for CONFIG_MODULE_DECOMPRESS"
#endif
int module_decompress(struct load_info *info, const void *buf, size_t size)
{
unsigned int n_pages;
ssize_t data_size;
int error;
#if defined(CONFIG_MODULE_STATS)
info->compressed_len = size;
#endif
/*
* Start with number of pages twice as big as needed for
* compressed data.
*/
n_pages = DIV_ROUND_UP(size, PAGE_SIZE) * 2;
error = module_extend_max_pages(info, n_pages);
data_size = MODULE_DECOMPRESS_FN(info, buf, size);
if (data_size < 0) {
error = data_size;
goto err;
}
info->hdr = vmap(info->pages, info->used_pages, VM_MAP, PAGE_KERNEL);
if (!info->hdr) {
error = -ENOMEM;
goto err;
}
info->len = data_size;
return 0;
err:
module_decompress_cleanup(info);
return error;
}
void module_decompress_cleanup(struct load_info *info)
{
int i;
if (info->hdr)
vunmap(info->hdr);
for (i = 0; i < info->used_pages; i++)
__free_page(info->pages[i]);
kvfree(info->pages);
info->pages = NULL;
info->max_pages = info->used_pages = 0;
}
#ifdef CONFIG_SYSFS
static ssize_t compression_show(struct kobject *kobj,
struct kobj_attribute *attr, char *buf)
{
return sysfs_emit(buf, __stringify(MODULE_COMPRESSION) "\n");
}
static struct kobj_attribute module_compression_attr = __ATTR_RO(compression);
static int __init module_decompress_sysfs_init(void)
{
int error;
error = sysfs_create_file(&module_kset->kobj,
&module_compression_attr.attr);
if (error)
pr_warn("Failed to create 'compression' attribute");
return 0;
}
late_initcall(module_decompress_sysfs_init);
#endif
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