-const char deanimate_rcs[] = "$Id: deanimate.c,v 1.11 2002/03/26 22:29:54 swa Exp $";
+const char deanimate_rcs[] = "$Id: deanimate.c,v 1.16 2007/07/14 08:01:58 fabiankeil Exp $";
/*********************************************************************
*
* File : $Source: /cvsroot/ijbswa/current/deanimate.c,v $
*
- * Purpose : Declares functions to deanimate GIF images on the fly.
+ * Purpose : Declares functions to manipulate binary images on the
+ * fly. High-level functions include:
+ * - Deanimation of GIF images
+ * - Fixup of malformed comment block in JPEG headers
*
* Functions declared include: gif_deanimate, buf_free,
- * buf_copy, buf_getbyte, gif_skip_data_block, and
- * gif_extract_image
+ * buf_copy, buf_getbyte, gif_skip_data_block,
+ * gif_extract_image and jpeg_inspect
*
- * Copyright : Written by and Copyright (C) 2001 by the the SourceForge
- * Privoxy team. http://www.privoxy.org/
+ * Copyright : Written by and Copyright (C) 2001 - 2004, 2006 by the
+ * SourceForge Privoxy team. http://www.privoxy.org/
*
* Based on the GIF file format specification (see
* http://tronche.com/computer-graphics/gif/gif89a.html)
*
* Revisions :
* $Log: deanimate.c,v $
+ * Revision 1.16 2007/07/14 08:01:58 fabiankeil
+ * s@failiure@failure@
+ *
+ * Revision 1.15 2007/01/03 14:39:19 fabiankeil
+ * Fix a gcc43 warning and mark the binbuffer
+ * as immutable for buf_getbyte().
+ *
+ * Revision 1.14 2006/07/18 14:48:45 david__schmidt
+ * Reorganizing the repository: swapping out what was HEAD (the old 3.1 branch)
+ * with what was really the latest development (the v_3_0_branch branch)
+ *
+ * Revision 1.12.2.1 2004/10/03 12:53:32 david__schmidt
+ * Add the ability to check jpeg images for invalid
+ * lengths of comment blocks. Defensive strategy
+ * against the exploit:
+ * Microsoft Security Bulletin MS04-028
+ * Buffer Overrun in JPEG Processing (GDI+) Could
+ * Allow Code Execution (833987)
+ * Enabled with +inspect-jpegs in actions files.
+ *
+ * Revision 1.12 2002/05/12 21:36:29 jongfoster
+ * Correcting function comments
+ *
* Revision 1.11 2002/03/26 22:29:54 swa
* we have a new homepage!
*
#include <string.h>
#include <fcntl.h>
+#include "errlog.h"
#include "project.h"
#include "deanimate.h"
#include "miscutil.h"
* 2 : length = Desired minimum size
*
*
- * Returns : 0 on success, 1 on failiure.
+ * Returns : 0 on success, 1 on failure.
*
*********************************************************************/
-int buf_extend(struct binbuffer *buf, size_t length)
+static int buf_extend(struct binbuffer *buf, size_t length)
{
char *newbuf;
* 2 : dst = Pointer to the destination binbuffer
* 3 : length = Number of bytes to be copied
*
- * Returns : 0 on success, 1 on failiure.
+ * Returns : 0 on success, 1 on failure.
*
*********************************************************************/
-int buf_copy(struct binbuffer *src, struct binbuffer *dst, size_t length)
+static int buf_copy(struct binbuffer *src, struct binbuffer *dst, size_t length)
{
/*
* 1 : src = Pointer to the source binbuffer
* 2 : offset = Offset to the desired byte
*
- * Returns : The byte on success, or 0 on failiure
+ * Returns : The byte on success, or 0 on failure
*
*********************************************************************/
-unsigned char buf_getbyte(struct binbuffer *src, size_t offset)
+static unsigned char buf_getbyte(const struct binbuffer *src, size_t offset)
{
if (src->offset + offset < src->size)
{
* Parameters :
* 1 : buf = Pointer to the binbuffer
*
- * Returns : 0 on success, or 1 on failiure
+ * Returns : 0 on success, or 1 on failure
*
*********************************************************************/
-int gif_skip_data_block(struct binbuffer *buf)
+static int gif_skip_data_block(struct binbuffer *buf)
{
unsigned char c;
*/
while((c = buf_getbyte(buf, 0)) != '\0')
{
- if ((buf->offset += c + 1) >= buf->size - 1)
+ buf->offset += (size_t)c + 1;
+ if (buf->offset >= buf->size - 1)
{
return 1;
}
* 1 : src = Pointer to the source binbuffer
* 2 : dst = Pointer to the destination binbuffer
*
- * Returns : 0 on success, or 1 on failiure
+ * Returns : 0 on success, or 1 on failure
*
*********************************************************************/
-int gif_extract_image(struct binbuffer *src, struct binbuffer *dst)
+static int gif_extract_image(struct binbuffer *src, struct binbuffer *dst)
{
unsigned char c;
-
+
/*
* Remember the colormap flag and copy the image head
*/
* 3 : get_first_image = Flag: If set, get the first image
* If unset (default), get the last
*
- * Returns : 0 on success, or 1 on failiure
+ * Returns : 0 on success, or 1 on failure
*
*********************************************************************/
int gif_deanimate(struct binbuffer *src, struct binbuffer *dst, int get_first_image)
}
+/*********************************************************************
+ *
+ * Function : jpeg_inspect
+ *
+ * Description : Checks a jpeg image for an invalid length in a
+ * comment block (0xFFFE0000 or 0xFFFE0001) and
+ * changes it to 0xFFFE0002. Defensive strategy
+ * against the exploit:
+ * Microsoft Security Bulletin MS04-028
+ * Buffer Overrun in JPEG Processing (GDI+) Could
+ * Allow Code Execution (833987)
+ *
+ * Parameters :
+ * 1 : src = Pointer to the image binbuffer
+ *
+ * Returns : 0 on success, or 1 on failure
+ *
+ *********************************************************************/
+int jpeg_inspect(struct binbuffer *src, struct binbuffer *dst)
+{
+ long i;
+ /*
+ * We process the image using a simple finite state machine,
+ * searching for byte patterns.
+ */
+ enum { J_INIT, /* The initial state */
+ J_FF, /* Found byte 0xFF */
+ J_FE, /* Found bytes 0xFF 0xFE */
+ J_00, /* Found bytes 0xFF 0xFE 0x00 */
+ J_DA /*
+ * Found bytes 0xFF 0xDA; short-circuit to done-ness
+ * since this signals the beginning end of headers.
+ */
+ };
+ short state = J_INIT;
+ unsigned char c;
+
+ if (NULL == src || NULL == dst)
+ {
+ return 1;
+ }
+
+ if (buf_copy(src, dst, src->size))
+ {
+ return 1;
+ }
+
+ /* Need to search the jpg for patterns:
+ * 0xFF 0xFE 0x00 0x00
+ * or
+ * 0xFF 0xFE 0x00 0x01
+ * from beginning until:
+ * 0xFF 0xDA
+ * (or the end of the buffer)
+ * If found, change the pattern to 0xFF 0xFE 0x00 0x02
+ */
+
+ for (i = 0; i < dst->size; i++)
+ {
+ c = dst->buffer[i];
+ switch (state)
+ {
+ case J_INIT:
+ if (c == 0xFF)
+ state = J_FF;
+ break;
+ case J_FF:
+ if (c == 0xDA)
+ state = J_DA; /* End of headers - we're done with this image. */
+ else if (c == 0xFE)
+ state = J_FE;
+ else
+ state = J_INIT;
+ break;
+ case J_FE:
+ if (c == 0x00)
+ state = J_00;
+ else
+ state = J_INIT;
+ break;
+ case J_00:
+ if ((c == 0x00) || (c == 0x01))
+ {
+ dst->buffer[i] = 2; /* Reset comment block size to 2. */
+ log_error(LOG_LEVEL_INFO, "JPEG comment exploit removed.");
+ /* TODO:
+ * I'm unsure if we can have more than one comment block. Just in case,
+ * we'll scan the rest of the header for more by going back to J_INIT
+ * state. If there is no possibility of >1 comment block, we could
+ * short-circuit to done-ness here.
+ */
+ state = J_INIT;
+ }
+ else
+ state = J_INIT;
+ break;
+ default:
+ break;
+ }
+ if (state == J_DA)
+ break;
+ }
+
+ return 0;
+}
+
+
/*
Local Variables:
tab-width: 3
projects / privoxy.git / blobdiff