[deflate] Remove userptr_t from decompression code

Simplify the deflate, zlib, and gzip decompression code by assuming
that all content is fully accessible via pointer dereferences.

Signed-off-by: Michael Brown <mcb30@ipxe.org>

3 files changed, 64 insertions, 62 deletions

diff --git a/src/image/gzip.c b/src/image/gzip.c
index 116d912d7..b72c3243e 100644
--- a/src/image/gzip.c
+++ b/src/image/gzip.c
@@ -24,10 +24,10 @@
 FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
 
 #include <stdlib.h>
+#include <string.h>
 #include <errno.h>
 #include <assert.h>
 #include <ipxe/deflate.h>
-#include <ipxe/uaccess.h>
 #include <ipxe/image.h>
 #include <ipxe/zlib.h>
 #include <ipxe/gzip.h>
@@ -46,83 +46,92 @@ FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
  * @ret rc		Return status code
  */
 static int gzip_extract ( struct image *image, struct image *extracted ) {
-	struct gzip_header header;
-	struct gzip_extra_header extra;
-	struct gzip_crc_header crc;
-	struct gzip_footer footer;
-	struct deflate_chunk in;
-	unsigned int strings;
-	size_t offset;
+	const struct gzip_header *header;
+	const struct gzip_extra_header *extra;
+	const struct gzip_crc_header *crc;
+	const struct gzip_footer *footer;
+	const void *data;
+	size_t extra_len;
+	size_t string_len;
 	size_t len;
-	off_t nul;
+	unsigned int strings;
 	int rc;
 
 	/* Sanity check */
-	assert ( image->len >= ( sizeof ( header ) + sizeof ( footer ) ) );
+	assert ( image->len >= ( sizeof ( *header ) + sizeof ( *footer ) ) );
+	data = image->data;
+	len = image->len;
 
 	/* Extract footer */
-	len = ( image->len - sizeof ( footer ) );
-	copy_from_user ( &footer, image->data, len, sizeof ( footer ) );
+	assert ( len >= sizeof ( *footer ) );
+	len -= sizeof ( *footer );
+	footer = ( data + len );
 
 	/* Extract fixed header */
-	copy_from_user ( &header, image->data, 0, sizeof ( header ) );
-	offset = sizeof ( header );
-	assert ( offset <= ( image->len - sizeof ( footer ) ) );
+	assert ( len >= sizeof ( *header ) );
+	header = data;
+	data += sizeof ( *header );
+	len -= sizeof ( *header );
 
 	/* Skip extra header, if present */
-	if ( header.flags & GZIP_FL_EXTRA ) {
-		copy_from_user ( &extra, image->data, offset,
-				 sizeof ( extra ) );
-		offset += sizeof ( extra );
-		offset += le16_to_cpu ( extra.len );
-		if ( offset > len ) {
+	if ( header->flags & GZIP_FL_EXTRA ) {
+		if ( len < sizeof ( *extra ) ) {
 			DBGC ( image, "GZIP %p overlength extra header\n",
 			       image );
 			return -EINVAL;
 		}
+		extra = data;
+		data += sizeof ( *extra );
+		len -= sizeof ( *extra );
+		extra_len = le16_to_cpu ( extra->len );
+		if ( len < extra_len ) {
+			DBGC ( image, "GZIP %p overlength extra header\n",
+			       image );
+			return -EINVAL;
+		}
+		data += extra_len;
+		len -= extra_len;
 	}
-	assert ( offset <= ( image->len - sizeof ( footer ) ) );
 
 	/* Skip name and/or comment, if present */
 	strings = 0;
-	if ( header.flags & GZIP_FL_NAME )
+	if ( header->flags & GZIP_FL_NAME )
 		strings++;
-	if ( header.flags & GZIP_FL_COMMENT )
+	if ( header->flags & GZIP_FL_COMMENT )
 		strings++;
 	while ( strings-- ) {
-		nul = memchr_user ( image->data, offset, 0, ( len - offset ) );
-		if ( nul < 0 ) {
+		string_len = strnlen ( data, len );
+		if ( string_len == len ) {
 			DBGC ( image, "GZIP %p overlength name/comment\n",
 			       image );
 			return -EINVAL;
 		}
-		offset = ( nul + 1 /* NUL */ );
+		data += ( string_len + 1 /* NUL */ );
+		len -= ( string_len + 1 /* NUL */ );
 	}
-	assert ( offset <= ( image->len - sizeof ( footer ) ) );
 
 	/* Skip CRC, if present */
-	if ( header.flags & GZIP_FL_HCRC ) {
-		offset += sizeof ( crc );
-		if ( offset > len ) {
+	if ( header->flags & GZIP_FL_HCRC ) {
+		if ( len < sizeof ( *crc ) ) {
 			DBGC ( image, "GZIP %p overlength CRC header\n",
 			       image );
 			return -EINVAL;
 		}
+		data += sizeof ( *crc );
+		len -= sizeof ( *crc );
 	}
 
-	/* Initialise input chunk */
-	deflate_chunk_init ( &in, ( image->data + offset ), 0, len );
-
 	/* Presize extracted image */
 	if ( ( rc = image_set_len ( extracted,
-				    le32_to_cpu ( footer.len ) ) ) != 0 ) {
+				    le32_to_cpu ( footer->len ) ) ) != 0 ) {
 		DBGC ( image, "GZIP %p could not presize: %s\n",
 		       image, strerror ( rc ) );
 		return rc;
 	}
 
 	/* Decompress image (expanding if necessary) */
-	if ( ( rc = zlib_deflate ( DEFLATE_RAW, &in, extracted ) ) != 0 ) {
+	if ( ( rc = zlib_deflate ( DEFLATE_RAW, data, len,
+				   extracted ) ) != 0 ) {
 		DBGC ( image, "GZIP %p could not decompress: %s\n",
 		       image, strerror ( rc ) );
 		return rc;
@@ -138,19 +147,18 @@ static int gzip_extract ( struct image *image, struct image *extracted ) {
  * @ret rc		Return status code
  */
 static int gzip_probe ( struct image *image ) {
-	struct gzip_header header;
-	struct gzip_footer footer;
+	const struct gzip_header *header;
+	const struct gzip_footer *footer;
 
 	/* Sanity check */
-	if ( image->len < ( sizeof ( header ) + sizeof ( footer ) ) ) {
+	if ( image->len < ( sizeof ( *header ) + sizeof ( *footer ) ) ) {
 		DBGC ( image, "GZIP %p image too short\n", image );
 		return -ENOEXEC;
 	}
+	header = image->data;
 
 	/* Check magic header */
-	copy_from_user ( &header.magic, image->data, 0,
-			 sizeof ( header.magic ) );
-	if ( header.magic != cpu_to_be16 ( GZIP_MAGIC ) ) {
+	if ( header->magic != cpu_to_be16 ( GZIP_MAGIC ) ) {
 		DBGC ( image, "GZIP %p invalid magic\n", image );
 		return -ENOEXEC;
 	}
diff --git a/src/image/png.c b/src/image/png.c
index d5cf7fd8f..8b432e01a 100644
--- a/src/image/png.c
+++ b/src/image/png.c
@@ -336,13 +336,12 @@ static int png_palette ( struct image *image, struct png_context *png,
  */
 static int png_image_data ( struct image *image, struct png_context *png,
 			    size_t len ) {
-	struct deflate_chunk in;
 	int rc;
 
 	/* Deflate this chunk */
-	deflate_chunk_init ( &in, image->data, png->offset,
-			     ( png->offset + len ) );
-	if ( ( rc = deflate_inflate ( &png->deflate, &in, &png->raw ) ) != 0 ) {
+	if ( ( rc = deflate_inflate ( &png->deflate,
+				      ( image->data + png->offset ),
+				      len, &png->raw ) ) != 0 ) {
 		DBGC ( image, "PNG %s could not decompress: %s\n",
 		       image->name, strerror ( rc ) );
 		return rc;
diff --git a/src/image/zlib.c b/src/image/zlib.c
index a42c47e1b..d7deee88b 100644
--- a/src/image/zlib.c
+++ b/src/image/zlib.c
@@ -27,7 +27,6 @@ FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
 #include <errno.h>
 #include <assert.h>
 #include <ipxe/deflate.h>
-#include <ipxe/uaccess.h>
 #include <ipxe/image.h>
 #include <ipxe/zlib.h>
 
@@ -41,11 +40,12 @@ FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
  * Extract compressed data to image
  *
  * @v format		Compression format code
- * @v in		Compressed input chunk
+ * @v data		Compressed input data
+ * @v len		Length of compressed input data
  * @v extracted		Extracted image
  * @ret rc		Return status code
  */
-int zlib_deflate ( enum deflate_format format, struct deflate_chunk *in,
+int zlib_deflate ( enum deflate_format format, const void *data, size_t len,
 		   struct image *extracted ) {
 	struct deflate *deflate;
 	struct deflate_chunk out;
@@ -64,14 +64,12 @@ int zlib_deflate ( enum deflate_format format, struct deflate_chunk *in,
 		/* (Re)initialise decompressor */
 		deflate_init ( deflate, format );
 
-		/* (Re)initialise input chunk */
-		in->offset = 0;
-
 		/* Initialise output chunk */
 		deflate_chunk_init ( &out, extracted->data, 0, extracted->len );
 
 		/* Decompress data */
-		if ( ( rc = deflate_inflate ( deflate, in, &out ) ) != 0 ) {
+		if ( ( rc = deflate_inflate ( deflate, data, len,
+					      &out ) ) != 0 ) {
 			DBGC ( extracted, "ZLIB %p could not decompress: %s\n",
 			       extracted, strerror ( rc ) );
 			goto err_inflate;
@@ -116,14 +114,11 @@ int zlib_deflate ( enum deflate_format format, struct deflate_chunk *in,
  * @ret rc		Return status code
  */
 static int zlib_extract ( struct image *image, struct image *extracted ) {
-	struct deflate_chunk in;
 	int rc;
 
-	/* Initialise input chunk */
-	deflate_chunk_init ( &in, image->data, 0, image->len );
-
 	/* Decompress image */
-	if ( ( rc = zlib_deflate ( DEFLATE_ZLIB, &in, extracted ) ) != 0 )
+	if ( ( rc = zlib_deflate ( DEFLATE_ZLIB, image->data, image->len,
+				   extracted ) ) != 0 )
 		return rc;
 
 	return 0;
@@ -136,17 +131,17 @@ static int zlib_extract ( struct image *image, struct image *extracted ) {
  * @ret rc		Return status code
  */
 static int zlib_probe ( struct image *image ) {
-	union zlib_magic magic;
+	const union zlib_magic *magic;
 
 	/* Sanity check */
-	if ( image->len < sizeof ( magic ) ) {
+	if ( image->len < sizeof ( *magic ) ) {
 		DBGC ( image, "ZLIB %p image too short\n", image );
 		return -ENOEXEC;
 	}
+	magic = image->data;
 
 	/* Check magic header */
-	copy_from_user ( &magic, image->data, 0, sizeof ( magic ) );
-	if ( ! zlib_magic_is_valid ( &magic ) ) {
+	if ( ! zlib_magic_is_valid ( magic ) ) {
 		DBGC ( image, "ZLIB %p invalid magic data\n", image );
 		return -ENOEXEC;
 	}