X-Git-Url: http://www.privoxy.org/gitweb/?p=privoxy.git;a=blobdiff_plain;f=deanimate.c;h=4e4aaacaa9cacf02e4ebdaaac40b73ea575eacb0;hp=59ed56e96c25bf64b84c6ea24663248f8392e3f8;hb=bd6912e45154b4479b165af980a54a0f16564e19;hpb=d3b49edb39bfc457d4c9047b01e1dbcdd3cf209e diff --git a/deanimate.c b/deanimate.c index 59ed56e9..4e4aaaca 100644 --- a/deanimate.c +++ b/deanimate.c @@ -1,16 +1,19 @@ -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) @@ -37,6 +40,29 @@ const char deanimate_rcs[] = "$Id: deanimate.c,v 1.11 2002/03/26 22:29:54 swa Ex * * 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! * @@ -80,6 +106,7 @@ const char deanimate_rcs[] = "$Id: deanimate.c,v 1.11 2002/03/26 22:29:54 swa Ex #include #include +#include "errlog.h" #include "project.h" #include "deanimate.h" #include "miscutil.h" @@ -126,10 +153,10 @@ void buf_free(struct binbuffer *buf) * 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; @@ -167,10 +194,10 @@ int buf_extend(struct binbuffer *buf, size_t length) * 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) { /* @@ -213,10 +240,10 @@ 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) { @@ -242,10 +269,10 @@ unsigned char buf_getbyte(struct binbuffer *src, size_t offset) * 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; @@ -256,7 +283,8 @@ int gif_skip_data_block(struct binbuffer *buf) */ 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; } @@ -281,13 +309,13 @@ int gif_skip_data_block(struct binbuffer *buf) * 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 */ @@ -346,7 +374,7 @@ int gif_extract_image(struct binbuffer *src, struct binbuffer *dst) * 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) @@ -497,6 +525,113 @@ 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 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