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denyhosts/clamscan/libclamav/pdfdecode.c

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2022-10-22 18:41:00 +08:00
/*
* Copyright (C) 2016-2022 Cisco and/or its affiliates. All rights reserved.
*
* Author: Kevin Lin
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
* MA 02110-1301, USA.
*
* In addition, as a special exception, the copyright holders give
* permission to link the code of portions of this program with the
* OpenSSL library under certain conditions as described in each
* individual source file, and distribute linked combinations
* including the two.
*
* You must obey the GNU General Public License in all respects
* for all of the code used other than OpenSSL. If you modify
* file(s) with this exception, you may extend this exception to your
* version of the file(s), but you are not obligated to do so. If you
* do not wish to do so, delete this exception statement from your
* version. If you delete this exception statement from all source
* files in the program, then also delete it here.
*/
#if HAVE_CONFIG_H
#include "clamav-config.h"
#endif
#include <stdio.h>
#include <stddef.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <ctype.h>
#include <string.h>
#include <fcntl.h>
#include <stdlib.h>
#include <errno.h>
#ifdef HAVE_LIMITS_H
#include <limits.h>
#endif
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif
#include <zlib.h>
#if HAVE_ICONV
#include <iconv.h>
#endif
#include "clamav.h"
#include "others.h"
#include "pdf.h"
#include "pdfdecode.h"
#include "str.h"
#include "bytecode.h"
#include "bytecode_api.h"
#include "lzw/lzwdec.h"
#define PDFTOKEN_FLAG_XREF 0x1
#define INFLATE_CHUNK_SIZE (1024 * 256)
struct pdf_token {
uint32_t flags; /* tracking flags */
uint32_t success; /* successfully decoded filters */
uint32_t length; /* length of current content; TODO: transition to size_t */
uint8_t *content; /* content stream */
};
static size_t pdf_decodestream_internal(struct pdf_struct *pdf, struct pdf_obj *obj, struct pdf_dict *params, struct pdf_token *token, int fout, cl_error_t *status, struct objstm_struct *objstm);
static cl_error_t pdf_decode_dump(struct pdf_struct *pdf, struct pdf_obj *obj, struct pdf_token *token, uint32_t lvl);
static cl_error_t filter_ascii85decode(struct pdf_struct *pdf, struct pdf_obj *obj, struct pdf_token *token);
static cl_error_t filter_rldecode(struct pdf_struct *pdf, struct pdf_obj *obj, struct pdf_token *token);
static cl_error_t filter_flatedecode(struct pdf_struct *pdf, struct pdf_obj *obj, struct pdf_dict *params, struct pdf_token *token);
static cl_error_t filter_asciihexdecode(struct pdf_struct *pdf, struct pdf_obj *obj, struct pdf_token *token);
static cl_error_t filter_decrypt(struct pdf_struct *pdf, struct pdf_obj *obj, struct pdf_dict *params, struct pdf_token *token, int mode);
static cl_error_t filter_lzwdecode(struct pdf_struct *pdf, struct pdf_obj *obj, struct pdf_dict *params, struct pdf_token *token);
/**
* @brief Wrapper function for pdf_decodestream_internal.
*
* Allocate a token object to store decoded filter data.
* Parse/decode the filter data and scan it.
*
* @param pdf Pdf context structure.
* @param obj The object we found the filter content in.
* @param params (optional) Dictionary parameters describing the filter data.
* @param stream Filter stream buffer pointer.
* @param streamlen Length of filter stream buffer.
* @param xref Indicates if the stream is an /XRef stream. Do not apply forced decryption on /XRef streams.
* @param fout File descriptor to write to to be scanned.
* @param[out] rc Return code ()
* @param objstm (optional) Object stream context structure.
* @return size_t The number of bytes written to 'fout' to be scanned.
*/
size_t pdf_decodestream(
struct pdf_struct *pdf, struct pdf_obj *obj, struct pdf_dict *params,
const char *stream, uint32_t streamlen, int xref, int fout, cl_error_t *status,
struct objstm_struct *objstm)
{
struct pdf_token *token = NULL;
size_t bytes_scanned = 0;
cli_ctx *ctx = NULL;
if (!status) {
/* invalid args, and no way to pass back the status code */
return 0;
}
if (!pdf || !obj) {
/* Invalid args */
*status = CL_EARG;
goto done;
}
ctx = pdf->ctx;
if (!stream || !streamlen || fout < 0) {
cli_dbgmsg("pdf_decodestream: no filters or stream on obj %u %u\n", obj->id >> 8, obj->id & 0xff);
*status = CL_ENULLARG;
goto done;
}
*status = CL_SUCCESS;
#if 0
if (params)
pdf_print_dict(params, 0);
#endif
token = cli_malloc(sizeof(struct pdf_token));
if (!token) {
*status = CL_EMEM;
goto done;
}
token->flags = 0;
if (xref)
token->flags |= PDFTOKEN_FLAG_XREF;
token->success = 0;
token->content = cli_malloc(streamlen);
if (!token->content) {
*status = CL_EMEM;
goto done;
}
memcpy(token->content, stream, streamlen);
token->length = streamlen;
cli_dbgmsg("pdf_decodestream: detected %lu applied filters\n", (long unsigned)(obj->numfilters));
bytes_scanned = pdf_decodestream_internal(pdf, obj, params, token, fout, status, objstm);
if ((CL_VIRUS == *status) && !SCAN_ALLMATCHES) {
goto done;
}
if (0 == token->success) {
/*
* Either:
* a) it failed to decode any filters, or
* b) there were no filters.
*
* Write out the raw stream to be scanned.
*
* Nota bene: If it did decode any filters, the internal() function would
* have written out the decoded stream to be scanned.
*/
if (!cli_checklimits("pdf", pdf->ctx, streamlen, 0, 0)) {
cli_dbgmsg("pdf_decodestream: no non-forced filters decoded, returning raw stream\n");
if (cli_writen(fout, stream, streamlen) != streamlen) {
cli_errmsg("pdf_decodestream: failed to write raw stream to output file\n");
} else {
bytes_scanned = streamlen;
}
}
}
done:
/*
* Free up the token, and token content, if any.
*/
if (NULL != token) {
if (NULL != token->content) {
free(token->content);
token->content = NULL;
token->length = 0;
}
free(token);
token = NULL;
}
return bytes_scanned;
}
/**
* @brief Decode filter buffer data.
*
* Attempt to decompress, decrypt or otherwise parse it.
*
* @param pdf Pdf context structure.
* @param obj The object we found the filter content in.
* @param params (optional) Dictionary parameters describing the filter data.
* @param token Pointer to and length of filter data.
* @param fout File handle to write data to to be scanned.
* @param[out] status CL_CLEAN/CL_SUCCESS or CL_VIRUS/CL_E<error>
* @param objstm (optional) Object stream context structure.
* @return ptrdiff_t The number of bytes we wrote to 'fout'. -1 if failed out.
*/
static size_t pdf_decodestream_internal(
struct pdf_struct *pdf, struct pdf_obj *obj, struct pdf_dict *params,
struct pdf_token *token, int fout, cl_error_t *status, struct objstm_struct *objstm)
{
cl_error_t vir = CL_CLEAN;
cl_error_t retval = CL_SUCCESS;
size_t bytes_scanned = 0;
cli_ctx *ctx = NULL;
const char *filter = NULL;
uint32_t i;
if (!status) {
/* invalid args, and no way to pass back the status code */
return 0;
}
if (!pdf || !obj || !token) {
/* Invalid args */
*status = CL_EARG;
goto done;
}
ctx = pdf->ctx;
*status = CL_SUCCESS;
/*
* if pdf is decryptable, scan for CRYPT filter
* if none, force a DECRYPT filter application
*/
if ((pdf->flags & (1 << DECRYPTABLE_PDF)) && !(obj->flags & (1 << OBJ_FILTER_CRYPT))) {
if (token->flags & PDFTOKEN_FLAG_XREF) /* TODO: is this on all crypt filters or only the assumed one? */
cli_dbgmsg("pdf_decodestream_internal: skipping decoding => non-filter CRYPT (reason: xref)\n");
else {
cli_dbgmsg("pdf_decodestream_internal: decoding => non-filter CRYPT\n");
retval = filter_decrypt(pdf, obj, params, token, 1);
if (retval != CL_SUCCESS) {
*status = CL_EPARSE;
goto done;
}
}
}
for (i = 0; i < obj->numfilters; i++) {
switch (obj->filterlist[i]) {
case OBJ_FILTER_A85:
cli_dbgmsg("pdf_decodestream_internal: decoding [%u] => ASCII85DECODE\n", obj->filterlist[i]);
retval = filter_ascii85decode(pdf, obj, token);
break;
case OBJ_FILTER_RL:
cli_dbgmsg("pdf_decodestream_internal: decoding [%u] => RLDECODE\n", obj->filterlist[i]);
retval = filter_rldecode(pdf, obj, token);
break;
case OBJ_FILTER_FLATE:
cli_dbgmsg("pdf_decodestream_internal: decoding [%u] => FLATEDECODE\n", obj->filterlist[i]);
retval = filter_flatedecode(pdf, obj, params, token);
break;
case OBJ_FILTER_AH:
cli_dbgmsg("pdf_decodestream_internal: decoding [%u] => ASCIIHEXDECODE\n", obj->filterlist[i]);
retval = filter_asciihexdecode(pdf, obj, token);
break;
case OBJ_FILTER_CRYPT:
cli_dbgmsg("pdf_decodestream_internal: decoding [%u] => CRYPT\n", obj->filterlist[i]);
retval = filter_decrypt(pdf, obj, params, token, 0);
break;
case OBJ_FILTER_LZW:
cli_dbgmsg("pdf_decodestream_internal: decoding [%u] => LZWDECODE\n", obj->filterlist[i]);
retval = filter_lzwdecode(pdf, obj, params, token);
break;
case OBJ_FILTER_JPX:
if (!filter) filter = "JPXDECODE";
/*fallthrough*/
case OBJ_FILTER_DCT:
if (!filter) filter = "DCTDECODE";
/*fallthrough*/
case OBJ_FILTER_FAX:
if (!filter) filter = "FAXDECODE";
/*fallthrough*/
case OBJ_FILTER_JBIG2:
if (!filter) filter = "JBIG2DECODE";
cli_dbgmsg("pdf_decodestream_internal: unimplemented filter type [%u] => %s\n", obj->filterlist[i], filter);
filter = NULL;
retval = CL_BREAK;
break;
default:
cli_dbgmsg("pdf_decodestream_internal: unknown filter type [%u]\n", obj->filterlist[i]);
retval = CL_BREAK;
break;
}
if (!(token->content) || !(token->length)) {
cli_dbgmsg("pdf_decodestream_internal: empty content, breaking after %u (of %u) filters\n", i, obj->numfilters);
break;
}
if (retval != CL_SUCCESS) {
if (retval == CL_VIRUS && SCAN_ALLMATCHES) {
vir = CL_VIRUS;
} else {
const char *reason;
switch (retval) {
case CL_VIRUS:
*status = CL_VIRUS;
reason = "detection";
break;
case CL_BREAK:
*status = CL_SUCCESS;
reason = "decoding break";
break;
default:
*status = CL_EPARSE;
reason = "decoding error";
break;
}
cli_dbgmsg("pdf_decodestream_internal: stopping after %d (of %u) filters (reason: %s)\n", i, obj->numfilters, reason);
break;
}
}
token->success++;
/* Dump the stream content to a text file if keeptmp is enabled. */
if (pdf->ctx->engine->keeptmp) {
if (CL_SUCCESS != pdf_decode_dump(pdf, obj, token, i + 1)) {
cli_errmsg("pdf_decodestream_internal: failed to write decoded stream content to temp file\n");
}
}
}
if ((token->success > 0) && (NULL != token->content)) {
/*
* Looks like we successfully decoded some or all of the stream filters,
* so lets write it out to a file descriptor we scan.
*
* In the event that we didn't decode any filters (or maybe there
* weren't any filters), the calling function will do the same with
* the raw stream.
*/
if (CL_SUCCESS == cli_checklimits("pdf", pdf->ctx, token->length, 0, 0)) {
if (cli_writen(fout, token->content, token->length) != token->length) {
cli_errmsg("pdf_decodestream_internal: failed to write decoded stream content to output file\n");
} else {
bytes_scanned = token->length;
}
}
}
if ((NULL != objstm) &&
((CL_SUCCESS == *status) || ((CL_VIRUS == *status) && SCAN_ALLMATCHES))) {
unsigned int objs_found = pdf->nobjs;
/*
* The caller indicated that the decoded data is an object stream.
* Perform experimental object stream parsing to extract objects from the stream.
*/
objstm->streambuf = (char *)token->content;
objstm->streambuf_len = (size_t)token->length;
/* Take ownership of the malloc'd buffer */
token->content = NULL;
token->length = 0;
/* Don't store the result. It's ok if some or all objects failed to parse.
It would be far worse to add objects from a stream to the list, and then free
the stream buffer due to an "error". */
if (CL_SUCCESS != pdf_find_and_parse_objs_in_objstm(pdf, objstm)) {
cli_dbgmsg("pdf_decodestream_internal: pdf_find_and_parse_objs_in_objstm failed!\n");
}
if (pdf->nobjs <= objs_found) {
cli_dbgmsg("pdf_decodestream_internal: pdf_find_and_parse_objs_in_objstm did not find any new objects!\n");
} else {
cli_dbgmsg("pdf_decodestream_internal: pdf_find_and_parse_objs_in_objstm found %u new objects.\n", pdf->nobjs - objs_found);
}
}
done:
if (vir == CL_VIRUS)
*status = CL_VIRUS;
return bytes_scanned;
}
/**
* @brief Dump PDF filter content such as stream contents to a temp file.
*
* Temp file is created in the pdf->dir directory.
* Filename format is "pdf<pdf->files-1>_<lvl>".
*
* @param pdf Pdf context structure.
* @param obj The object we found the filter content in.
* @param token The struct for the filter contents.
* @param lvl A unique index to distinguish the files from each other.
* @return cl_error_t
*/
static cl_error_t pdf_decode_dump(struct pdf_struct *pdf, struct pdf_obj *obj, struct pdf_token *token, uint32_t lvl)
{
char fname[1024];
int ifd;
snprintf(fname, sizeof(fname), "%s" PATHSEP "pdf%02u_%02u", pdf->dir, (pdf->files - 1), lvl);
ifd = open(fname, O_RDWR | O_CREAT | O_EXCL | O_TRUNC | O_BINARY, 0600);
if (ifd < 0) {
char err[128];
cli_errmsg("cli_pdf: can't create intermediate temporary file %s: %s\n", fname, cli_strerror(errno, err, sizeof(err)));
return CL_ETMPFILE;
}
cli_dbgmsg("cli_pdf: decoded filter %u obj %u %u\n", lvl, obj->id >> 8, obj->id & 0xff);
cli_dbgmsg(" ... to %s\n", fname);
if (cli_writen(ifd, token->content, token->length) != token->length) {
cli_errmsg("cli_pdf: failed to write output file\n");
close(ifd);
return CL_EWRITE;
}
close(ifd);
return CL_SUCCESS;
}
/*
* ascii85 inflation
* See http://www.piclist.com/techref/method/encode.htm (look for base85)
*/
static cl_error_t filter_ascii85decode(struct pdf_struct *pdf, struct pdf_obj *obj, struct pdf_token *token)
{
uint8_t *decoded, *dptr;
uint32_t declen = 0;
const uint8_t *ptr = (uint8_t *)token->content;
uint32_t remaining = token->length;
int quintet = 0, rc = CL_SUCCESS;
uint64_t sum = 0;
/* 5:4 decoding ratio, with 1:4 expansion sequences => (4*length)+1 */
if (!(dptr = decoded = (uint8_t *)cli_malloc((4 * remaining) + 1))) {
cli_errmsg("cli_pdf: cannot allocate memory for decoded output\n");
return CL_EMEM;
}
if (cli_memstr((const char *)ptr, remaining, "~>", 2) == NULL)
cli_dbgmsg("cli_pdf: no EOF marker found\n");
while (remaining > 0) {
int byte = (remaining--) ? (int)*ptr++ : EOF;
if ((byte == '~') && (remaining > 0) && (*ptr == '>'))
byte = EOF;
if (byte >= '!' && byte <= 'u') {
sum = (sum * 85) + ((uint32_t)byte - '!');
if (++quintet == 5) {
*dptr++ = (unsigned char)(sum >> 24);
*dptr++ = (unsigned char)((sum >> 16) & 0xFF);
*dptr++ = (unsigned char)((sum >> 8) & 0xFF);
*dptr++ = (unsigned char)(sum & 0xFF);
declen += 4;
quintet = 0;
sum = 0;
}
} else if (byte == 'z') {
if (quintet) {
cli_dbgmsg("cli_pdf: unexpected 'z'\n");
rc = CL_EFORMAT;
break;
}
*dptr++ = '\0';
*dptr++ = '\0';
*dptr++ = '\0';
*dptr++ = '\0';
declen += 4;
} else if (byte == EOF) {
cli_dbgmsg("cli_pdf: last quintet contains %d bytes\n", quintet);
if (quintet) {
int i;
if (quintet == 1) {
cli_dbgmsg("cli_pdf: invalid last quintet (only 1 byte)\n");
rc = CL_EFORMAT;
break;
}
for (i = quintet; i < 5; i++)
sum *= 85;
if (quintet > 1)
sum += (0xFFFFFF >> ((quintet - 2) * 8));
for (i = 0; i < quintet - 1; i++)
*dptr++ = (uint8_t)((sum >> (24 - 8 * i)) & 0xFF);
declen += quintet - 1;
}
break;
} else if (!isspace(byte)) {
cli_dbgmsg("cli_pdf: invalid character 0x%x @ %lu\n",
byte & 0xFF, (unsigned long)(token->length - remaining));
rc = CL_EFORMAT;
break;
}
}
if (rc == CL_SUCCESS) {
free(token->content);
cli_dbgmsg("cli_pdf: deflated %lu bytes from %lu total bytes\n",
(unsigned long)declen, (unsigned long)(token->length));
token->content = decoded;
token->length = declen;
} else {
if (!(obj->flags & ((1 << OBJ_IMAGE) | (1 << OBJ_TRUNCATED))))
pdfobj_flag(pdf, obj, BAD_ASCIIDECODE);
cli_dbgmsg("cli_pdf: error occurred parsing byte %lu of %lu\n",
(unsigned long)(token->length - remaining), (unsigned long)(token->length));
free(decoded);
}
return rc;
}
/* imported from razorback */
static cl_error_t filter_rldecode(struct pdf_struct *pdf, struct pdf_obj *obj, struct pdf_token *token)
{
uint8_t *decoded, *temp;
uint32_t declen = 0, capacity = 0;
uint8_t *content = (uint8_t *)token->content;
uint32_t length = token->length;
uint32_t offset = 0;
int rc = CL_SUCCESS;
UNUSEDPARAM(obj);
capacity = INFLATE_CHUNK_SIZE;
if (!(decoded = (uint8_t *)cli_malloc(capacity))) {
cli_errmsg("cli_pdf: cannot allocate memory for decoded output\n");
return CL_EMEM;
}
while (offset < length) {
uint8_t srclen = content[offset++];
if (srclen < 128) {
/* direct copy of (srclen + 1) bytes */
if (offset + srclen + 1 > length) {
cli_dbgmsg("cli_pdf: required source length (%lu) exceeds remaining length (%lu)\n",
(long unsigned)(offset + srclen + 1), (long unsigned)(length - offset));
rc = CL_EFORMAT;
break;
}
if (declen + srclen + 1 > capacity) {
if ((rc = cli_checklimits("pdf", pdf->ctx, capacity + INFLATE_CHUNK_SIZE, 0, 0)) != CL_SUCCESS)
break;
if (!(temp = cli_realloc(decoded, capacity + INFLATE_CHUNK_SIZE))) {
cli_errmsg("cli_pdf: cannot reallocate memory for decoded output\n");
rc = CL_EMEM;
break;
}
decoded = temp;
capacity += INFLATE_CHUNK_SIZE;
}
memcpy(decoded + declen, content + offset, srclen + 1);
offset += srclen + 1;
declen += srclen + 1;
} else if (srclen > 128) {
/* copy the next byte (257 - srclen) times */
if (offset + 1 > length) {
cli_dbgmsg("cli_pdf: required source length (%lu) exceeds remaining length (%lu)\n",
(long unsigned)(offset + srclen + 1), (long unsigned)(length - offset));
rc = CL_EFORMAT;
break;
}
if (declen + (257 - srclen) + 1 > capacity) {
if ((rc = cli_checklimits("pdf", pdf->ctx, capacity + INFLATE_CHUNK_SIZE, 0, 0)) != CL_SUCCESS) {
cli_dbgmsg("cli_pdf: required buffer size to inflate compressed filter exceeds maximum: %u\n", capacity + INFLATE_CHUNK_SIZE);
break;
}
if (!(temp = cli_realloc(decoded, capacity + INFLATE_CHUNK_SIZE))) {
cli_errmsg("cli_pdf: cannot reallocate memory for decoded output\n");
rc = CL_EMEM;
break;
}
decoded = temp;
capacity += INFLATE_CHUNK_SIZE;
}
memset(decoded + declen, content[offset], 257 - srclen);
offset++;
declen += 257 - srclen;
} else { /* srclen == 128 */
/* end of data */
cli_dbgmsg("cli_pdf: end-of-stream marker @ offset %lu (%lu bytes remaining)\n",
(unsigned long)offset, (long unsigned)(token->length - offset));
break;
}
}
if (rc == CL_SUCCESS) {
if (declen == 0) {
cli_dbgmsg("cli_pdf: empty stream after inflation completed.\n");
rc = CL_BREAK;
} else if (!(temp = cli_realloc(decoded, declen))) {
/* Shrink output buffer to final the decoded data length to minimize RAM usage */
cli_errmsg("cli_pdf: cannot reallocate memory for decoded output\n");
rc = CL_EMEM;
} else {
decoded = temp;
}
}
if (rc == CL_SUCCESS || rc == CL_BREAK) {
free(token->content);
cli_dbgmsg("cli_pdf: decoded %lu bytes from %lu total bytes\n",
(unsigned long)declen, (unsigned long)(token->length));
token->content = decoded;
token->length = declen;
} else {
cli_dbgmsg("cli_pdf: error occurred parsing byte %lu of %lu\n",
(unsigned long)offset, (unsigned long)(token->length));
free(decoded);
}
return rc;
}
static uint8_t *decode_nextlinestart(uint8_t *content, uint32_t length)
{
uint8_t *pt = content;
uint32_t r;
int toggle = 0;
for (r = 0; r < length; r++, pt++) {
if (*pt == '\n' || *pt == '\r')
toggle = 1;
else if (toggle)
break;
}
return pt;
}
static cl_error_t filter_flatedecode(struct pdf_struct *pdf, struct pdf_obj *obj, struct pdf_dict *params, struct pdf_token *token)
{
uint8_t *decoded, *temp;
uint32_t declen = 0, capacity = 0;
uint8_t *content = (uint8_t *)token->content;
uint32_t length = token->length;
z_stream stream;
int zstat, rc = CL_SUCCESS;
UNUSEDPARAM(params);
if (*content == '\r') {
content++;
length--;
pdfobj_flag(pdf, obj, BAD_STREAMSTART);
/* PDF spec says stream is followed by \r\n or \n, but not \r alone.
* Sample 0015315109, it has \r followed by zlib header.
* Flag pdf as suspicious, and attempt to extract by skipping the \r.
*/
if (!length)
return CL_SUCCESS;
}
capacity = INFLATE_CHUNK_SIZE;
if (!(decoded = (uint8_t *)cli_malloc(capacity))) {
cli_errmsg("cli_pdf: cannot allocate memory for decoded output\n");
return CL_EMEM;
}
memset(&stream, 0, sizeof(stream));
stream.next_in = (Bytef *)content;
stream.avail_in = length;
stream.next_out = (Bytef *)decoded;
stream.avail_out = INFLATE_CHUNK_SIZE;
zstat = inflateInit(&stream);
if (zstat != Z_OK) {
cli_warnmsg("cli_pdf: inflateInit failed\n");
free(decoded);
return CL_EMEM;
}
/* initial inflate */
zstat = inflate(&stream, Z_NO_FLUSH);
/* check if nothing written whatsoever */
if ((zstat != Z_OK) && (stream.avail_out == INFLATE_CHUNK_SIZE)) {
/* skip till EOL, and try inflating from there, sometimes
* PDFs contain extra whitespace */
uint8_t *q = decode_nextlinestart(content, length);
if (q) {
(void)inflateEnd(&stream);
length -= q - content;
content = q;
stream.next_in = (Bytef *)content;
stream.avail_in = length;
stream.next_out = (Bytef *)decoded;
stream.avail_out = capacity;
zstat = inflateInit(&stream);
if (zstat != Z_OK) {
cli_warnmsg("cli_pdf: inflateInit failed\n");
free(decoded);
return CL_EMEM;
}
pdfobj_flag(pdf, obj, BAD_FLATESTART);
}
zstat = inflate(&stream, Z_NO_FLUSH);
}
while (zstat == Z_OK && stream.avail_in) {
/* extend output capacity if needed,*/
if (stream.avail_out == 0) {
if ((rc = cli_checklimits("pdf", pdf->ctx, capacity + INFLATE_CHUNK_SIZE, 0, 0)) != CL_SUCCESS) {
cli_dbgmsg("cli_pdf: required buffer size to inflate compressed filter exceeds maximum: %u\n", capacity + INFLATE_CHUNK_SIZE);
break;
}
if (!(temp = cli_realloc(decoded, capacity + INFLATE_CHUNK_SIZE))) {
cli_errmsg("cli_pdf: cannot reallocate memory for decoded output\n");
rc = CL_EMEM;
break;
}
decoded = temp;
stream.next_out = decoded + capacity;
stream.avail_out = INFLATE_CHUNK_SIZE;
declen += INFLATE_CHUNK_SIZE;
capacity += INFLATE_CHUNK_SIZE;
}
/* continue inflation */
zstat = inflate(&stream, Z_NO_FLUSH);
}
/* add stream end fragment to decoded length */
declen += (INFLATE_CHUNK_SIZE - stream.avail_out);
/* error handling */
switch (zstat) {
case Z_OK:
cli_dbgmsg("cli_pdf: Z_OK on stream inflation completion\n");
/* intentional fall-through */
case Z_STREAM_END:
cli_dbgmsg("cli_pdf: inflated %lu bytes from %lu total bytes (%lu bytes remaining)\n",
(unsigned long)declen, (unsigned long)(token->length), (unsigned long)(stream.avail_in));
break;
/* potentially fatal - *mostly* ignored as per older version */
case Z_STREAM_ERROR:
case Z_NEED_DICT:
case Z_DATA_ERROR:
case Z_MEM_ERROR:
default:
if (stream.msg)
cli_dbgmsg("cli_pdf: after writing %lu bytes, got error \"%s\" inflating PDF stream in %u %u obj\n",
(unsigned long)declen, stream.msg, obj->id >> 8, obj->id & 0xff);
else
cli_dbgmsg("cli_pdf: after writing %lu bytes, got error %d inflating PDF stream in %u %u obj\n",
(unsigned long)declen, zstat, obj->id >> 8, obj->id & 0xff);
if (declen == 0) {
pdfobj_flag(pdf, obj, BAD_FLATESTART);
cli_dbgmsg("cli_pdf: no bytes were inflated.\n");
rc = CL_EFORMAT;
} else {
pdfobj_flag(pdf, obj, BAD_FLATE);
}
break;
}
(void)inflateEnd(&stream);
if (rc == CL_SUCCESS) {
if (declen == 0) {
cli_dbgmsg("cli_pdf: empty stream after inflation completed.\n");
rc = CL_BREAK;
} else if (!(temp = cli_realloc(decoded, declen))) {
/* Shrink output buffer to final the decoded data length to minimize RAM usage */
cli_errmsg("cli_pdf: cannot reallocate memory for decoded output\n");
rc = CL_EMEM;
} else {
decoded = temp;
}
}
if (rc == CL_SUCCESS || rc == CL_BREAK) {
free(token->content);
token->content = decoded;
token->length = declen;
} else {
cli_dbgmsg("cli_pdf: error occurred parsing byte %lu of %lu\n",
(unsigned long)(length - stream.avail_in), (unsigned long)(token->length));
free(decoded);
}
return rc;
}
static cl_error_t filter_asciihexdecode(struct pdf_struct *pdf, struct pdf_obj *obj, struct pdf_token *token)
{
uint8_t *decoded;
const uint8_t *content = (uint8_t *)token->content;
uint32_t length = token->length;
uint32_t i, j;
cl_error_t rc = CL_SUCCESS;
if (!(decoded = (uint8_t *)cli_calloc(length / 2 + 1, sizeof(uint8_t)))) {
cli_errmsg("cli_pdf: cannot allocate memory for decoded output\n");
return CL_EMEM;
}
for (i = 0, j = 0; i + 1 < length; i++) {
if (content[i] == ' ')
continue;
if (content[i] == '>')
break;
if (cli_hex2str_to((const char *)content + i, (char *)decoded + j, 2) == -1) {
if (length - i < 4)
continue;
rc = CL_EFORMAT;
break;
}
i++;
j++;
}
if (rc == CL_SUCCESS) {
free(token->content);
cli_dbgmsg("cli_pdf: deflated %lu bytes from %lu total bytes\n",
(unsigned long)j, (unsigned long)(token->length));
token->content = decoded;
token->length = j;
} else {
if (!(obj->flags & ((1 << OBJ_IMAGE) | (1 << OBJ_TRUNCATED))))
pdfobj_flag(pdf, obj, BAD_ASCIIDECODE);
cli_dbgmsg("cli_pdf: error occurred parsing byte %lu of %lu\n",
(unsigned long)i, (unsigned long)(token->length));
free(decoded);
}
return rc;
}
/* modes: 0 = use default/DecodeParms, 1 = use document setting */
static cl_error_t filter_decrypt(struct pdf_struct *pdf, struct pdf_obj *obj, struct pdf_dict *params, struct pdf_token *token, int mode)
{
char *decrypted;
size_t length = (size_t)token->length;
enum enc_method enc = ENC_IDENTITY;
if (mode)
enc = get_enc_method(pdf, obj);
else if (params) {
struct pdf_dict_node *node = params->nodes;
while (node) {
if (node->type == PDF_DICT_STRING) {
if (!strncmp(node->key, "/Type", 6)) { /* optional field - Type */
/* MUST be "CryptFilterDecodeParms" */
if (node->value)
cli_dbgmsg("cli_pdf: Type: %s\n", (char *)(node->value));
} else if (!strncmp(node->key, "/Name", 6)) { /* optional field - Name */
/* overrides document and default encryption method */
if (node->value)
cli_dbgmsg("cli_pdf: Name: %s\n", (char *)(node->value));
enc = parse_enc_method(pdf->CF, pdf->CF_n, (char *)(node->value), enc);
}
}
node = node->next;
}
}
decrypted = decrypt_any(pdf, obj->id, (const char *)token->content, &length, enc);
if (!decrypted) {
cli_dbgmsg("cli_pdf: failed to decrypt stream\n");
return CL_EPARSE; /* TODO: what should this value be? CL_SUCCESS would mirror previous behavior */
}
cli_dbgmsg("cli_pdf: decrypted %zu bytes from %u total bytes\n",
length, token->length);
free(token->content);
token->content = (uint8_t *)decrypted;
token->length = (uint32_t)length; /* this may truncate unfortunately, TODO: use 64-bit values internally? */
return CL_SUCCESS;
}
static cl_error_t filter_lzwdecode(struct pdf_struct *pdf, struct pdf_obj *obj, struct pdf_dict *params, struct pdf_token *token)
{
uint8_t *decoded, *temp;
uint32_t declen = 0, capacity = 0;
uint8_t *content = (uint8_t *)token->content;
uint32_t length = token->length;
lzw_stream stream;
int echg = 1, lzwstat, rc = CL_SUCCESS;
if (pdf->ctx && !(pdf->ctx->dconf->other & OTHER_CONF_LZW))
return CL_BREAK;
if (params) {
struct pdf_dict_node *node = params->nodes;
while (node) {
if (node->type == PDF_DICT_STRING) {
if (!strncmp(node->key, "/EarlyChange", 13)) { /* optional field - lzw flag */
char *end, *value = (char *)node->value;
long set;
if (value) {
cli_dbgmsg("cli_pdf: EarlyChange: %s\n", value);
set = strtol(value, &end, 10);
if (end != value)
echg = (int)set;
}
}
}
node = node->next;
}
}
if (*content == '\r') {
content++;
length--;
pdfobj_flag(pdf, obj, BAD_STREAMSTART);
/* PDF spec says stream is followed by \r\n or \n, but not \r alone.
* Sample 0015315109, it has \r followed by zlib header.
* Flag pdf as suspicious, and attempt to extract by skipping the \r.
*/
if (!length)
return CL_SUCCESS;
}
capacity = INFLATE_CHUNK_SIZE;
if (!(decoded = (uint8_t *)cli_malloc(capacity))) {
cli_errmsg("cli_pdf: cannot allocate memory for decoded output\n");
return CL_EMEM;
}
memset(&stream, 0, sizeof(stream));
stream.next_in = content;
stream.avail_in = length;
stream.next_out = decoded;
stream.avail_out = INFLATE_CHUNK_SIZE;
if (echg)
stream.flags |= LZW_FLAG_EARLYCHG;
lzwstat = lzwInit(&stream);
if (lzwstat != Z_OK) {
cli_warnmsg("cli_pdf: lzwInit failed\n");
free(decoded);
return CL_EMEM;
}
/* initial inflate */
lzwstat = lzwInflate(&stream);
/* check if nothing written whatsoever */
if ((lzwstat != Z_OK) && (stream.avail_out == INFLATE_CHUNK_SIZE)) {
/* skip till EOL, and try inflating from there, sometimes
* PDFs contain extra whitespace */
uint8_t *q = decode_nextlinestart(content, length);
if (q) {
(void)lzwInflateEnd(&stream);
length -= q - content;
content = q;
stream.next_in = (Bytef *)content;
stream.avail_in = length;
stream.next_out = (Bytef *)decoded;
stream.avail_out = capacity;
lzwstat = lzwInit(&stream);
if (lzwstat != Z_OK) {
cli_warnmsg("cli_pdf: lzwInit failed\n");
free(decoded);
return CL_EMEM;
}
pdfobj_flag(pdf, obj, BAD_FLATESTART);
}
lzwstat = lzwInflate(&stream);
}
while (lzwstat == Z_OK && stream.avail_in) {
/* extend output capacity if needed,*/
if (stream.avail_out == 0) {
if ((rc = cli_checklimits("pdf", pdf->ctx, capacity + INFLATE_CHUNK_SIZE, 0, 0)) != CL_SUCCESS) {
cli_dbgmsg("cli_pdf: required buffer size to inflate compressed filter exceeds maximum: %u\n", capacity + INFLATE_CHUNK_SIZE);
break;
}
if (!(temp = cli_realloc(decoded, capacity + INFLATE_CHUNK_SIZE))) {
cli_errmsg("cli_pdf: cannot reallocate memory for decoded output\n");
rc = CL_EMEM;
break;
}
decoded = temp;
stream.next_out = decoded + capacity;
stream.avail_out = INFLATE_CHUNK_SIZE;
declen += INFLATE_CHUNK_SIZE;
capacity += INFLATE_CHUNK_SIZE;
}
/* continue inflation */
lzwstat = lzwInflate(&stream);
}
/* add stream end fragment to decoded length */
declen += (INFLATE_CHUNK_SIZE - stream.avail_out);
/* error handling */
switch (lzwstat) {
case LZW_OK:
cli_dbgmsg("cli_pdf: LZW_OK on stream inflation completion\n");
/* intentional fall-through */
case LZW_STREAM_END:
cli_dbgmsg("cli_pdf: inflated %lu bytes from %lu total bytes (%lu bytes remaining)\n",
(unsigned long)declen, (unsigned long)(token->length), (unsigned long)(stream.avail_in));
break;
/* potentially fatal - *mostly* ignored as per older version */
case LZW_STREAM_ERROR:
case LZW_DATA_ERROR:
case LZW_MEM_ERROR:
case LZW_BUF_ERROR:
case LZW_DICT_ERROR:
default:
if (stream.msg)
cli_dbgmsg("cli_pdf: after writing %lu bytes, got error \"%s\" inflating PDF stream in %u %u obj\n",
(unsigned long)declen, stream.msg, obj->id >> 8, obj->id & 0xff);
else
cli_dbgmsg("cli_pdf: after writing %lu bytes, got error %d inflating PDF stream in %u %u obj\n",
(unsigned long)declen, lzwstat, obj->id >> 8, obj->id & 0xff);
if (declen == 0) {
pdfobj_flag(pdf, obj, BAD_FLATESTART);
cli_dbgmsg("cli_pdf: no bytes were inflated.\n");
rc = CL_EFORMAT;
} else {
pdfobj_flag(pdf, obj, BAD_FLATE);
}
break;
}
(void)lzwInflateEnd(&stream);
if (rc == CL_SUCCESS) {
if (declen == 0) {
cli_dbgmsg("cli_pdf: empty stream after inflation completed.\n");
rc = CL_BREAK;
} else if (!(temp = cli_realloc(decoded, declen))) {
/* Shrink output buffer to final the decoded data length to minimize RAM usage */
cli_errmsg("cli_pdf: cannot reallocate memory for decoded output\n");
rc = CL_EMEM;
} else {
decoded = temp;
}
}
if (rc == CL_SUCCESS || rc == CL_BREAK) {
free(token->content);
token->content = decoded;
token->length = declen;
} else {
cli_dbgmsg("cli_pdf: error occurred parsing byte %lu of %lu\n",
(unsigned long)(length - stream.avail_in), (unsigned long)(token->length));
free(decoded);
}
/*
heuristic checks:
- full dictionary heuristics?
- invalid code points?
*/
return rc;
}
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