X-Git-Url: http://www.privoxy.org/gitweb/?a=blobdiff_plain;f=deanimate.c;h=b9592e8fc44c00f94fb18bb9b5051659ca1406d6;hb=7df7fc1c547ddc6cddf161fab52358f7499cc9b1;hp=6d37759f254658699bd6987a094a7949f47772c0;hpb=17ef7337d1a41e4733c1ec662c3b1191d0c76a8a;p=privoxy.git diff --git a/deanimate.c b/deanimate.c index 6d37759f..b9592e8f 100644 --- a/deanimate.c +++ b/deanimate.c @@ -1,16 +1,19 @@ -const char deanimate_rcs[] = "$Id: deanimate.c,v 1.8 2002/03/09 19:42:47 jongfoster Exp $"; +const char deanimate_rcs[] = "$Id: deanimate.c,v 1.12.2.1 2004/10/03 12:53:32 david__schmidt Exp $"; /********************************************************************* * - * File : $Source: /cvsroot/ijbswa/current/deanimate.c,v $ + * File : $Source: /cvsroot/ijbswa/current/Attic/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 - * IJBSWA team. http://ijbswa.sourceforge.net + * Copyright : Written by and Copyright (C) 2001 - 2004 by the the + * SourceForge Privoxy team. http://www.privoxy.org/ * * Based on the GIF file format specification (see * http://tronche.com/computer-graphics/gif/gif89a.html) @@ -37,6 +40,27 @@ const char deanimate_rcs[] = "$Id: deanimate.c,v 1.8 2002/03/09 19:42:47 jongfos * * Revisions : * $Log: deanimate.c,v $ + * 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! + * + * Revision 1.10 2002/03/24 13:25:43 swa + * name change related issues + * + * Revision 1.9 2002/03/13 00:27:04 jongfoster + * Killing warnings + * * Revision 1.8 2002/03/09 19:42:47 jongfoster * Fixing more warnings * @@ -71,6 +95,7 @@ const char deanimate_rcs[] = "$Id: deanimate.c,v 1.8 2002/03/09 19:42:47 jongfos #include #include +#include "errlog.h" #include "project.h" #include "deanimate.h" #include "miscutil.h" @@ -201,7 +226,7 @@ int buf_copy(struct binbuffer *src, struct binbuffer *dst, size_t length) * given offset * * Parameters : - * 1 : buf = Pointer to the source binbuffer + * 1 : src = Pointer to the source binbuffer * 2 : offset = Offset to the desired byte * * Returns : The byte on success, or 0 on failiure @@ -488,6 +513,113 @@ write: } +/********************************************************************* + * + * 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 failiure + * + *********************************************************************/ +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