It seems better not to compress signature dictionaries. Various PDF
digital signing tools, including Adobe Acrobat Reader DC, do not
compress signature dictionaries.
Table 8.93 "Entries in a signature dictionary" in PDF 1.5 reference
describes that /ByteRange in the signature dictionary shall be used to
describe a digest that does not include the signature value
(/Contents) itself.
The byte ranges cannot be determined if the dictionary is compressed.
When seeing to a position based on a value read from the input, we are
prone to integer overflow (fuzz issue 15442). Seek in two stages to
move the overflow check into the input source code.
This makes all integer type conversions that have potential data loss
explicit with calls that do range checks and raise an exception. After
this commit, qpdf builds with no warnings when -Wsign-conversion
-Wconversion is used with gcc or clang or when -W3 -Wd4800 is used
with MSVC. This significantly reduces the likelihood of potential
crashes from bogus integer values.
There are some parts of the code that take int when they should take
size_t or an offset. Such places would make qpdf not support files
with more than 2^31 of something that usually wouldn't be so large. In
the event that such a file shows up and is valid, at least qpdf would
raise an error in the right spot so the issue could be legitimately
addressed rather than failing in some weird way because of a silent
overflow condition.
* [bcc32 Error] QPDF.cc(375): E2268 Call to undefined function 'atof'
Full parser context
QPDF.cc(358): parsing: void QPDF::parse(const char *)
* [bcc32 Error] QPDFTokenizer.cc(183): E2268 Call to undefined function 'strtol'
Full parser context
QPDFTokenizer.cc(163): parsing: void QPDFTokenizer::resolveLiteral()
* [bcc32 Error] pdf-split-pages.cc(52): E2268 Call to undefined function 'exit'
Full parser context
pdf-split-pages.cc(50): parsing: void usage()
* PR #295: Including "cstdlib" should be replaced with "stdlib.h" to be more consistent. At the same time I changed the order of the surrounding includes to reflect alphabetical order, because at some files this already have been the case.
The original QPDF is only required now when the source
QPDFObjectHandle is a stream that gets its stream data from a
QPDFObjectHandle::StreamDataProvider.
Instead of calling assert for problems found during checking
linearization data, throw an exception which is later caught and
issued as an error. Ideally we would handle errors more robustly, but
this is still a significant improvement.
On certain operations, such as iterating through all objects and
adding new indirect objects, walk through the entire object structure
and explicitly resolve any indirect references to non-existent
objects. That prevents new objects from springing into existence and
causing the previously dangling references to point to them.
Prior to this fix, if there was a loop detected in following /Prev
pointers in xref streams/tables, it would cause qpdf to lose data.
Note that this condition causes many PDF readers to hang or fail.
Bump to an alpha release. This version is not being widely released
but is being used to push the new shared library version through the
debian packaging system and to test out github releases.
Add options to enable the raw encryption key to be directly shown or
specified. Thanks to Didier Stevens <didier.stevens@gmail.com> for the
idea and contribution of one implementation of this idea.
While scanning the file looking for objects, limit the length of
tokens we allow. This prevents us from getting caught up in reading a
file character by character while digging through large streams.
This commit adds several API methods that enable control over which
types of filters QPDF will attempt to decode. It also adds support for
/RunLengthDecode and /DCTDecode filters for both encoding and
decoding.
Very badly corrupted files may not have a retrievable root dictionary.
Handle that as a special case so that a more helpful error message can
be provided.
When requested, QPDFWriter will do more aggress prechecking of streams
to make sure it can actually succeed in decoding them before
attempting to do so. This will allow preservation of raw data even
when the raw data is corrupted relative to the specified filters.
QPDFObjectHandle::parseInternal now issues warnings instead of
throwing exceptions for all error conditions that it finds (except
internal logic errors) and has stronger recovery for things like
invalid tokens and malformed dictionaries. This should improve qpdf's
ability to recover from a wide range of broken files that currently
cause it to fail.
During parsing of an object, sometimes parts of the object have to be
resolved. An example is stream lengths. If such an object directly or
indirectly points to the object being parsed, it can cause an infinite
loop. Guard against all cases of re-entrant resolution of objects.
This is CVE-2017-9208.
The QPDF library uses object ID 0 internally as a sentinel to
represent a direct object, but prior to this fix, was not blocking
handling of 0 0 obj or 0 0 R as a special case. Creating an object in
the file with 0 0 obj could cause various infinite loops. The PDF spec
doesn't allow for object 0. Having qpdf handle object 0 might be a
better fix, but changing all the places in the code that assumes objid
== 0 means direct would be risky.
The /W array was not sanitized, possibly causing an integer overflow
in a multiplication. An analysis of the code suggests that there were
no possible exploits based on this since the problems were in checking
expected values but bounds checks were performed on actual values.
4.2.0 was binary incompatible in spite of there being no deletions or
changes to any public methods. As such, we have to bump the ABI and
are fixing some API breakage while we're at it.
Previous 4.3.0 target is now 5.1.0.
Space rather than newline after xref, missing /ID in trailer for
encrypted file. This enables qpdf to handle some files that xpdf can
handle. Adobe reader can't necessarily handle them.
Rework QPDFWriter to always track old object IDs and QPDFObjGen
instead of int, thus not discarding the generation number. Switch to
QPDF::getCompressibleObjGen() to properly handle the case of an old
object eligible for compression that has a generation of other than
zero.
Read and write support is implemented for /V=5 with /R=5 as well as
/R=6. /R=5 is the deprecated encryption method used by Acrobat IX.
/R=6 is the encryption method used by PDF 2.0 from ISO 32000-2.
Allowing users to subclass InputSource and Pipeline to read and write
from/to arbitrary sources provides the maximum flexibility for users
who want to read and write from other than files or memory.
Move object parsing code from QPDF to QPDFObjectHandle and
parameterize the parts of it that are specific to a QPDF object.
Provide a version that can't handle indirect objects and that can be
called on an arbitrary string.
A side effect of this change is that the offset used when reporting
invalid stream length has changed, but since the new value seems like
a better value than the old one, the test suite has been updated
rather than making the code backward compatible. This only effects
the offset reported for invalid streams that lack /Length or have an
invalid /Length key.
Updated some test code and exmaples to use QPDFObjectHandle::parse.
Supporting changes include adding a BufferInputSource constructor that
takes a string.
QPDFObjectHandle::{new,is,assert}Reserved, QPDF::replaceReserved
provide a mechanism to add objects to a PDF file when there are
circular references. This is a prerequisite to copying objects from
one PDF to another.
Also updated pdf_from_scratch test driver to use the new factories,
and made some cosmetic improvements and documentation updates for the
emptyPDF() method.
