X-Git-Url: http://www.privoxy.org/gitweb/?p=privoxy.git;a=blobdiff_plain;f=deanimate.c;h=b9592e8fc44c00f94fb18bb9b5051659ca1406d6;hp=f7aead82c1e8c7172be887b60488b9d285b0e68f;hb=d42a366b562c60b5f1b88bfdfde4e2f94f45b4ec;hpb=da23dc8543fc54465eb3d247c7b67188cce2abcd diff --git a/deanimate.c b/deanimate.c index f7aead82..b9592e8f 100644 --- a/deanimate.c +++ b/deanimate.c @@ -1,16 +1,19 @@ -const char deanimate_rcs[] = "$Id: deanimate.c,v 1.4 2001/07/18 12:28:49 oes 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 +40,39 @@ const char deanimate_rcs[] = "$Id: deanimate.c,v 1.4 2001/07/18 12:28:49 oes Exp * * 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 + * + * Revision 1.7 2002/03/08 17:46:04 jongfoster + * Fixing int/size_t warnings + * + * Revision 1.6 2002/03/07 03:46:17 oes + * Fixed compiler warnings + * + * Revision 1.5 2001/09/10 10:16:06 oes + * Silenced compiler warnings + * * Revision 1.4 2001/07/18 12:28:49 oes * - Added feature for extracting the first frame * to gif_deanimate @@ -59,6 +95,7 @@ const char deanimate_rcs[] = "$Id: deanimate.c,v 1.4 2001/07/18 12:28:49 oes Exp #include #include +#include "errlog.h" #include "project.h" #include "deanimate.h" #include "miscutil.h" @@ -97,7 +134,7 @@ void buf_free(struct binbuffer *buf) * * Description : Ensure that a given binbuffer can hold a given amount * of bytes, by reallocating its buffer if necessary. - * Allocate new mem in chunks of 1000 bytes, so we don't + * Allocate new mem in chunks of 1024 bytes, so we don't * have to realloc() too often. * * Parameters : @@ -108,13 +145,13 @@ void buf_free(struct binbuffer *buf) * Returns : 0 on success, 1 on failiure. * *********************************************************************/ -int buf_extend(struct binbuffer *buf, int length) +int buf_extend(struct binbuffer *buf, size_t length) { char *newbuf; if (buf->offset + length > buf->size) { - buf->size = buf->size + length + 1000 - (buf->size + length) % 1000; + buf->size = ((buf->size + length + (size_t)1023) & ~(size_t)1023); newbuf = (char *)realloc(buf->buffer, buf->size); if (newbuf == NULL) @@ -149,7 +186,7 @@ int buf_extend(struct binbuffer *buf, int length) * Returns : 0 on success, 1 on failiure. * *********************************************************************/ -int buf_copy(struct binbuffer *src, struct binbuffer *dst, int length) +int buf_copy(struct binbuffer *src, struct binbuffer *dst, size_t length) { /* @@ -189,13 +226,13 @@ int buf_copy(struct binbuffer *src, struct binbuffer *dst, int 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 * *********************************************************************/ -unsigned char buf_getbyte(struct binbuffer *src, int offset) +unsigned char buf_getbyte(struct binbuffer *src, size_t offset) { if (src->offset + offset < src->size) { @@ -233,7 +270,7 @@ int gif_skip_data_block(struct binbuffer *buf) * by a one-byte length field, with the last chunk having * zero length. */ - while((c = buf_getbyte(buf, 0))) + while((c = buf_getbyte(buf, 0)) != '\0') { if ((buf->offset += c + 1) >= buf->size - 1) { @@ -281,7 +318,7 @@ int gif_extract_image(struct binbuffer *src, struct binbuffer *dst) */ if (c & 0x80) { - if (buf_copy(src, dst, 3 * (1 << ((c & 0x07) + 1)))) + if (buf_copy(src, dst, (size_t) 3 * (1 << ((c & 0x07) + 1)))) { return 1; } @@ -291,9 +328,9 @@ int gif_extract_image(struct binbuffer *src, struct binbuffer *dst) /* * Copy the image chunk by chunk. */ - while((c = buf_getbyte(src, 0))) + while((c = buf_getbyte(src, 0)) != '\0') { - if (buf_copy(src, dst, c + 1)) return 1; + if (buf_copy(src, dst, 1 + (size_t) c)) return 1; } if (buf_copy(src, dst, 1)) return 1; @@ -360,7 +397,7 @@ int gif_deanimate(struct binbuffer *src, struct binbuffer *dst, int get_first_im */ if(c & 0x80) { - if (buf_copy(src, dst, 3 * (1 << ((c & 0x07) + 1)))) + if (buf_copy(src, dst, (size_t) 3 * (1 << ((c & 0x07) + 1)))) { return 1; } @@ -476,6 +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