Reviewed-by: Piotr Gorski <lucjan.lucjanov@xxxxxxxxx>
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@xxxxxxxxx>
Cc: Piotr Gorski <lucjan.lucjanov@xxxxxxxxx>
Cc: Nick Terrell <terrelln@xxxxxx>
Signed-off-by: Stephen Boyd <swboyd@xxxxxxxxxxxx>
---
kernel/module/Kconfig | 3 +-
kernel/module/decompress.c | 92 +++++++++++++++++++++++++++++++++++++-
2 files changed, 92 insertions(+), 3 deletions(-)
diff --git a/kernel/module/Kconfig b/kernel/module/Kconfig
index 26ea5d04f56c..424b3bc58f3f 100644
--- a/kernel/module/Kconfig
+++ b/kernel/module/Kconfig
@@ -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
diff --git a/kernel/module/decompress.c b/kernel/module/decompress.c
index c033572d83f0..44f14643d014 100644
--- a/kernel/module/decompress.c
+++ b/kernel/module/decompress.c
@@ -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
base-commit: 76dcd734eca23168cb008912c0f69ff408905235
