128 lines
3.8 KiB
Diff
128 lines
3.8 KiB
Diff
From b18ce97c672615bb5ac44883676b37a9ec758d83 Mon Sep 17 00:00:00 2001
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From: Stefan Fritsch <sf@sfritsch.de>
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Date: Sun, 1 May 2016 14:32:30 +0200
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Subject: [PATCH] Implement checksum verification for gunzip
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This implements the crc32 check for the gzip format. Support for zlib's
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adler checksum is not included, yet.
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---
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grub-core/io/gzio.c | 46 +++++++++++++++++++++++++++++++++++++++++-----
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1 file changed, 41 insertions(+), 5 deletions(-)
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diff --git a/grub-core/io/gzio.c b/grub-core/io/gzio.c
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index a8e33033bf8..dcf3a870147 100644
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--- a/grub-core/io/gzio.c
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+++ b/grub-core/io/gzio.c
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@@ -43,6 +43,7 @@
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#include <grub/dl.h>
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#include <grub/deflate.h>
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#include <grub/i18n.h>
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+#include <grub/crypto.h>
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GRUB_MOD_LICENSE ("GPLv3+");
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@@ -94,6 +95,14 @@ struct grub_gzio
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struct huft *tl;
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/* The distance code table. */
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struct huft *td;
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+ /* The checksum algorithm */
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+ const gcry_md_spec_t *hdesc;
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+ /* The wanted checksum */
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+ grub_uint32_t orig_checksum;
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+ /* The uncompressed length */
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+ grub_size_t orig_len;
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+ /* Context for checksum calculation */
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+ grub_uint8_t *hcontext;
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/* The lookup bits for the literal/length code table. */
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int bl;
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/* The lookup bits for the distance code table. */
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@@ -180,7 +189,7 @@ test_gzip_header (grub_file_t file)
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grub_uint8_t os_type;
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} hdr;
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grub_uint16_t extra_len;
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- grub_uint32_t orig_len;
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+ grub_uint32_t crc32;
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grub_gzio_t gzio = file->data;
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if (grub_file_tell (gzio->file) != 0)
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@@ -215,12 +224,15 @@ test_gzip_header (grub_file_t file)
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/* FIXME: don't do this on not easily seekable files. */
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{
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- grub_file_seek (gzio->file, grub_file_size (gzio->file) - 4);
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- if (grub_file_read (gzio->file, &orig_len, 4) != 4)
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+ grub_file_seek (gzio->file, grub_file_size (gzio->file) - 8);
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+ if (grub_file_read (gzio->file, &crc32, 4) != 4)
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+ return 0;
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+ gzio->orig_checksum = grub_le_to_cpu32 (crc32);
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+ if (grub_file_read (gzio->file, &gzio->orig_len, 4) != 4)
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return 0;
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/* FIXME: this does not handle files whose original size is over 4GB.
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But how can we know the real original size? */
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- file->size = grub_le_to_cpu32 (orig_len);
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+ file->size = grub_le_to_cpu32 (gzio->orig_len);
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}
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initialize_tables (gzio);
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@@ -1095,7 +1107,23 @@ inflate_window (grub_gzio_t gzio)
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gzio->saved_offset += gzio->wp;
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- /* XXX do CRC calculation here! */
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+ if (gzio->hcontext)
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+ {
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+ gzio->hdesc->write (gzio->hcontext, gzio->slide, gzio->wp);
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+
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+ if (gzio->saved_offset == gzio->orig_len)
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+ {
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+ grub_uint32_t csum;
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+
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+ gzio->hdesc->final (gzio->hcontext);
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+ csum = *(grub_uint32_t *)gzio->hdesc->read (gzio->hcontext);
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+ csum = grub_be_to_cpu32 (csum);
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+ if (csum != gzio->orig_checksum)
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+ grub_error (GRUB_ERR_BAD_COMPRESSED_DATA,
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+ "checksum mismatch %08x/%08x",
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+ gzio->orig_checksum, csum);
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+ }
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+ }
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}
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@@ -1118,6 +1146,9 @@ initialize_tables (grub_gzio_t gzio)
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huft_free (gzio->td);
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gzio->tl = NULL;
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gzio->td = NULL;
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+
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+ if (gzio->hcontext)
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+ gzio->hdesc->init(gzio->hcontext);
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}
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@@ -1143,6 +1174,9 @@ grub_gzio_open (grub_file_t io, const char *name __attribute__ ((unused)))
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gzio->file = io;
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+ gzio->hdesc = GRUB_MD_CRC32;
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+ gzio->hcontext = grub_malloc(gzio->hdesc->contextsize);
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+
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file->device = io->device;
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file->data = gzio;
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file->fs = &grub_gzio_fs;
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@@ -1151,6 +1185,7 @@ grub_gzio_open (grub_file_t io, const char *name __attribute__ ((unused)))
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if (! test_gzip_header (file))
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{
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grub_errno = GRUB_ERR_NONE;
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+ grub_free (gzio->hcontext);
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grub_free (gzio);
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grub_free (file);
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grub_file_seek (io, 0);
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@@ -1287,6 +1322,7 @@ grub_gzio_close (grub_file_t file)
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grub_file_close (gzio->file);
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huft_free (gzio->tl);
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huft_free (gzio->td);
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+ grub_free (gzio->hcontext);
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grub_free (gzio);
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/* No need to close the same device twice. */
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