Commit 169a58ad authored by Stephen Boyd's avatar Stephen Boyd Committed by Luis Chamberlain
Browse files

module/decompress: Support zstd in-kernel decompression 



Add support for zstd compressed modules to the in-kernel decompression
code. This allows zstd compressed modules to be decompressed by the
kernel, similar to the existing support for gzip and xz compressed
modules.

Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Cc: Piotr Gorski <lucjan.lucjanov@gmail.com>
Cc: Nick Terrell <terrelln@fb.com>
Signed-off-by: default avatarStephen Boyd <swboyd@chromium.org>
Reviewed-by: default avatarDmitry Torokhov <dmitry.torokhov@gmail.com>
Reviewed-by: default avatarPiotr Gorski <lucjan.lucjanov@gmail.com>
Signed-off-by: default avatarLuis Chamberlain <mcgrof@kernel.org>
parent c86a514f

kernel/module/Kconfig

+2 −1
Original line number Diff line number Diff line
@@ -221,9 +221,10 @@ endchoice 


config MODULE_DECOMPRESS

	bool "Support in-kernel module decompression"

	depends on MODULE_COMPRESS_GZIP || MODULE_COMPRESS_XZ

	depends on MODULE_COMPRESS_GZIP || MODULE_COMPRESS_XZ || MODULE_COMPRESS_ZSTD

	select ZLIB_INFLATE if MODULE_COMPRESS_GZIP

	select XZ_DEC if MODULE_COMPRESS_XZ

	select ZSTD_DECOMPRESS if MODULE_COMPRESS_ZSTD

	help



	  Support for decompressing kernel modules by the kernel itself

kernel/module/decompress.c

+90 −2
Original line number Diff line number Diff line
@@ -50,7 +50,7 @@ static struct page *module_get_next_page(struct load_info *info) 
	return page;

}



#ifdef CONFIG_MODULE_COMPRESS_GZIP

#if defined(CONFIG_MODULE_COMPRESS_GZIP)

#include <linux/zlib.h>

#define MODULE_COMPRESSION	gzip

#define MODULE_DECOMPRESS_FN	module_gzip_decompress
@@ -141,7 +141,7 @@ static ssize_t module_gzip_decompress(struct load_info *info, 
	kfree(s.workspace);

	return retval;

}

#elif CONFIG_MODULE_COMPRESS_XZ

#elif defined(CONFIG_MODULE_COMPRESS_XZ)

#include <linux/xz.h>

#define MODULE_COMPRESSION	xz

#define MODULE_DECOMPRESS_FN	module_xz_decompress
@@ -199,6 +199,94 @@ static ssize_t module_xz_decompress(struct load_info *info, 
	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 = kmalloc(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(page);

		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:

	kfree(wksp);

	return retval;

}

#else

#error "Unexpected configuration for CONFIG_MODULE_DECOMPRESS"

#endif