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: Stephen Boyd <swboyd@chromium.org>
Reviewed-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Reviewed-by: Piotr Gorski <lucjan.lucjanov@gmail.com>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>

diff --git a/kernel/module/Kconfig b/kernel/module/Kconfig
index 26ea5d0..424b3bc 100644 (file)
--- 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 720e719..bb79ac1 100644 (file)
--- 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 @@ out:
        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