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The apt http code parses Content-Length and Content-Range. For
both requests the variable "Size" is used and the semantic for
this Size is the total file size. However Content-Length is not
the entire file size for partital file requests. For servers that
send the Content-Range header first and then the Content-Length
header this can lead to globbing of Size so that its less than
the real file size. This may lead to a subsequent passing of a
negative number into the CircleBuf which leads to a endless
loop that writes data.
Thanks to Anton Blanchard for the analysis and initial patch.
LP: #1445239
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Valid-Until protects us from long-living downgrade attacks, but not all
repositories have it and an attacker could still use older but still
valid files to downgrade us. While this makes it sounds like a security
improvement now, its a bit theoretical at best as an attacker with
capabilities to pull this off could just as well always keep us days
(but in the valid period) behind and always knows which state we have,
as we tell him with the If-Modified-Since header. This is also why this
is 'silently' ignored and treated as an IMSHit rather than screamed at
the user as this can at best be an annoyance for attackers.
An error here would 'regularily' be encountered by users by out-of-sync
mirrors serving a single run (e.g. load balancer) or in two consecutive
runs on the other hand, so it would just help teaching people ignore it.
That said, most of the code churn is caused by enforcing this additional
requirement. Crisscross from InRelease to Release.gpg is e.g. very
unlikely in practice, but if we would ignore it an attacker could
sidestep it this way.
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Not all servers we are talking to support If-Modified-Since and some are
not even sending Last-Modified for us, so in an effort to detect such
hits we run a hashsum check on the 'old' compared to the 'new' file, we
got the hashes for the 'new' already for "free" from the methods anyway
and hence just need to calculated the old ones.
This allows us to detect hits even with unsupported servers, which in
turn means we benefit from all the new hit behavior also here.
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It isn't used much compared to what the methodname suggests, but in the
remaining uses it can't hurt to check more than strictly necessary by
calculating and verifying with all hashes we can compare with rather
than "just" the best known hash.
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If we have the expected hashes we can check with them if the file we
have in partial we got a 416 for is the expected file. We detected this
with same-size before, but not every server sends a good Content-Range
header with a 416 response.
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While it is mostly busywork to rewrite all instances it actually fixes
bugs as the data storage used by the new method is std::string rather
than a char*, the later mostly created by c_str() from a std::string
which the caller has to ensure keeps in scope – something apt-ftparchive
actually didn't ensure and relied on copy-on-write behavior instead
which c++11 forbids and hence the new default gcc abi doesn't use it.
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TFRewrite is okay, but it has obscure limitations (256 Tags), even more
obscure bugs (order for renames is defined by the old name) and the
interface is very c-style encouraging bad usage like we do it in
apt-ftparchive passing massive amounts of c_str() from std::string in.
The old-style is marked as deprecated accordingly. The next commit will
fix all places in the apt code to not use the old-style anymore.
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In 66c3875df391b1120b43831efcbe88a78569fbfe we workaround/fixed a
problem where the code makes the assumption that the compiler uses
copy-on-write implementations for std::string. Turns out that for c++11
compatibility gcc >= 5 will stop doing this by default.
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dpkg and dak know various field names and order them in their output,
while we have yet another order and have to play catch up with them as
we are sitting between chairs here and neither order is ideal for us,
too.
A little testcase is from now on supposed to help ensureing that we do
not derivate to far away from which fields dpkg knows and orders.
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This rename with value is ordered by the 'old' name 'Source', but should
be ordered by the new name… by splitting the operation in a delete and a
new field we can easily fix this problem locally for now.
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The helper expects to be told if it should generate messages, not where
these messages should be printed – as it isn't printing such messages,
but puts them in _error. apt-get uses in other methods a helper
specialisation which does also print stuff to a stream through, so this
is likely a copy&paste error.
Git-Dch: Ignore
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Git-Dch: Ignore
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Slightly rewriting the code to ensure we only use two sources for the
versions as it could otherwise be confusing to look at.
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dpkg -l < 1.16.2 loads the available file and hence sees a package which
later versions do not see, leading to failures on travis-ci.
The different versions also have slightly different messages.
Git-Dch: Ignore
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If the pin for a generic pin is 0, it get a value by strange looking
rules, if the pin is specific the rules are at least not strange, but
the value 989 is a magic number without any direct meaning… but both
never happens in practice as the parsing skips such entries with a
warning, so there always is a priority != 0 and the code therefore never
used.
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The documentation says this, but the code only agreed while evaluating
specific packages, but not generics. These needed a pin above 1000 to
have the same effect.
The code causing this makes references to a 'second pesduo status file',
but nowhere is explained what this might stand for and/or what it was,
so we do the only reasonable thing: Remove all references and do as
documented.
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Git-Dch: Ignore
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Especially pdiff-enhanced downloads have the tendency to fail for
various reasons from which we can recover and even a successful download
used to leave the old unpatched index in partial/.
By adding a new method responsible for making the transaction of an
individual file happen we can at specialisations especially for abort
cases to deal with the cleanup.
This also helps in keeping the compressed indexes around if another
index failed instead of keeping the decompressed files, which we
wouldn't pick up in the next call.
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The fix for #777760 causes packages of foreign (and the native)
architectures, to be created correctly, but invalidates (like the
previously existing, but policy-forbidden architecture-less packages
we had to support for some upgrade scenarios) the assumption that the
first (and only) package in the cache for a single architecture system
must be the package for the native architecture (as, where should the
other architectures come from, right? Wrong.).
Depending on the order of parsing sources more or less packages can be
effected by this. The effects are strange (for apt it mostly effects
simulation/debug output, but also apt-mark on these specific packages),
which complicates debugging, but relatively harmless if understood as
most actions do not need direct named access to packages.
The problem is fixed by removing the single-arch special casing in the
paths who had them (Cache.FindPkg), so they use the same code as
multi-arch systems, which use them as a wrapper for Grp.FindPkg.
Note that single-arch system code was using Grp.FindPkg before as well
if a Grp structure was handily available, so we don't introduce new
untested code here: We remove more brittle special cases which are less
tested instead (this was planed to be done for Stretch anyhow).
Note further that the method with the assumption itself isn't fixed. As
it is a private method I opted for declaring it deprecated instead and
remove all its call positions. As it is private no-one can call this
method legally (thanks to how c++ works by default its still an exported
symbol through) and fixing it basically means reimplementing code we
already have in Grp.FindPkg.
Removing rather than fixing seems hence like a good solution.
Closes: 782777
Thanks: Axel Beckert for testing
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Conflicts:
apt-pkg/acquire-item.cc
cmdline/apt-key.in
methods/https.cc
test/integration/test-apt-key
test/integration/test-multiarch-foreign
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The sibling of this message are all guarded as debug messages, just this
one had it missing an subsequently causes display issues if triggered.
Git-Dch: Ignore
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If we get a IMSHit for the Transaction-Manager (= the InRelease file or
as its still supported fallback Release + Release.gpg combo) we can
assume that every file we would queue based on this manager, but already
have locally is current and hence would get an IMSHit, too. We therefore
save us and the server the trouble and skip the queuing in this case.
Beside speeding up repetative executions of 'apt-get update' this way we
also avoid hitting hashsum errors if the indexes are in fact already
updated, but the Release file isn't yet as it is the case on well
behaving mirrors as Release files is updated last.
The implementation is a bit harder than the theory makes it sound as we
still have to keep reverifying the Release files (e.g. to detect now expired
once to avoid an attacker being able to silently stale us) and have to
handle cases in which the Release file hits, but some indexes aren't
present (e.g. user added a new foreign architecture).
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Calculating the final name of an item which it will have after
everything is done and verified successfully is suprisingly complicated
as while they all follow a simple pattern, the URI and where it is
stored varies between the items.
With some (abibreaking) redesign we can abstract this similar to how it
is already down for the partial file location.
Git-Dch: Ignore
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Checking Valid-Until on an unsigned Release file doesn't give us any
security brownie points as an attacker could just change the date and in
practice repositories with unsigned Release files will very likely not
have a Valid-Until date, but for symetry and the fact that being
unsigned is currently just a warning, while expired is a fatal error.
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Its a bit unpredictable which permissons and owners we will encounter on
a CD-ROM (or a USB stick, as apt-cdrom is responsible for those too),
so we have to ensure in this codepath as well that everything is nicely
setup without waiting for a 'apt-get update' to fix up the (potential)
mess.
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We do this in HTTP already to give the CPU some exercise while the disk
is heavily spinning (or flashing?) to store the data avoiding the need
to reread the entire file again later on to calculate the hashes – which
happens outside of the eyes of progress reporting, so you might ended up
with a bunch of https workers 'stuck' at 100% while they were busy
calculating hashes.
This is a bummer for everyone using apt as a connection speedtest as the
https method works slower now (not really, it just isn't reporting done
too early anymore).
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Closes: 782122
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Methods get told which hashes are expected by the acquire system, which
means we can use this list to restrict what we calculate in the methods
as any extra we are calculating is wasted effort as we can't compare it
with anything anyway.
Adding support for a new hash algorithm is therefore 'free' now and if a
algorithm is no longer provided in a repository for a file, we
automatically stop calculating it.
In practice this results in a speed-up in Debian as we don't have SHA512
here (so far), so we practically stop calculating it.
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Git-Dch: Ignore
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Upstream claims its faster if combined with an optimizing compiler and
I can confirm that in some tests, so lets see how it works out in
practice.
Git-Dch: Ignore
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Servers who advertise that they close the connection get the 'Closes'
encoding flag, but this conflicts with servers who response with a
transfer-encoding (e.g. encoding) as it is saved in the same flag.
We have a better flag for the keep-alive (or not) of the connection
anyway, so we check this instead of the encoding.
This is in practice not much of a problem as real servers we talk to are
HTTP1.1 servers (with keep-alive) and there isn't much point in doing
chunked encoding if you are going to close anyway, but our simple
testserver stumbles over this if pressed and its a bit cleaner, too.
Git-Dch: Ignore
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file sends information about the uncompressed file if it can find it as
well as for the compressed file. This was done only for gzip so far, but
we support more compression types. That this information isn't used a
lot is a different story.
Git-Dch: Ignore
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Git-Dch: Ignore
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The worker expects that the methods tell him when they start or finish
downloading a file. Various information pieces are passed along in this
report including the (expected) filesize. https was using a "global"
struct for reporting which made it 'reuse' incorrect values in some
cases like a non-existent InRelease fallbacking to Release{,.gpg}
resulting in a size-mismatch warning. Reducing the scope and redesigning
the setting of the values we can fix this and related issues.
Closes: 777565, 781509
Thanks: Robert Edmonds and Anders Kaseorg for initial patchs
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It might be quite interesting which file (content) made curl freak out
and other methods keep the file around as well.
Git-Dch: Ignore
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We just need it for unit tests and our debian/rules file actually skips
calling them if nocheck is given… but this fails anyhow as we declared a
hard-dependency on it. Demoting the error to a warning in configuration
and adding a test in the 'make test' path with a friendly message allows
nocheck to be useful again.
(Running unit tests is fully encouraged of course, but bootstrappers and
co do not need to be burdened with this stuff)
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to 404"
This reverts commit 1296bc7c466181a7978c313c40a041b34ce3eaeb.
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On single-arch the parsing was creating groupnames like 'apt:amd64' even
through it should be 'apt' and a package in it belonging to architecture
amd64. The result for foreign architectures was as expected: The
dependency isn't satisfiable, but for native architecture it means the
wrong package (ala apt:amd64:amd64) is linked so this is also not
satisfiable, which is very much not expected.
No longer excluding single-arch from this codepath allows the generation
of the correct links, which still link to non-exisiting packages for
foreign dependencies, but natives link to the expected native package
just as if no architecture was given.
For negative arch-specific dependencies ala Conflicts this matter was
worse as apt will believe there isn't a Conflict to resolve, tricking it
into calculating a solution dpkg will refuse.
Architecture specific positive dependencies are rare in jessie – the
only one in amd64 main is foreign –, negative dependencies do not even
exist. Neither class has a native specimen, so no package in jessie is
effected by this bug, but it might be interesting for stretch upgrades.
This also means the regression potential is very low.
Closes: 777760
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In #780028 we were discussing how the or-group order should be more
important than keep-back decisions of 'upgrade'. We have this behaviour,
but to ensure it stays this way lets add a test for it.
Git-Dch: Ignore
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This isn't testing much of the 'complex' parts,
but its better than nothing for now.
Git-Dch: Ignore
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Working with strings c-style is complicated and error-prune,
so by converting to c++ style we gain some simplicity and
avoid buffer overflows by later extensions.
Git-Dch: Ignore
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gnupg is case-insensitive about keyids, so back then apt-key called it
directly any keyid was accepted, but now that we work more with the
keyid ourself we regressed to require uppercase keyids by accident.
This is also inconsistent with other apt-key commands which still use
gnupg directly. A single case-insensitive grep and we are fine again.
Closes: 781696
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g++-5 generates a slightly broken libapt which doesn't split
architecture configurations correctly resulting in e.g. Packages files
requested for the bogus architecture 'amd64,i386' instead of for amd64
and i386.
The reason is an incorrectly applied attribute marking the function as
const, while functions with pointer arguments are not allowed to be
declared as such (note that char& is a char* in disguise). Demoting the
attribute to pure fixes this issue – better would be dropping the & from
char but that is an API change…
Neither earlier g++ versions nor clang use this attribute to generate
broken code, so we don't need a rebuild of dependencies or anything and
g++-5 isn't even included in jessie, but the effect is so strange and
apt popular enough to consider avoiding this problem anyhow.
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libapt can be configured to write various bits of information to a file
creating a report via apport. This is disabled by default in Debian and
apport residing only in /experimental so far, but Ubuntu and other
derivatives have this (in some versions) enabled by default and there is
no regression potentially here.
The crash is caused by a mismatch of operations vs. strings for
operations, so adding the missing strings for these operations solves
the problem.
[commit message by David Kalnischkies]
LP: #1436626
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In /experimental this is resolved by deprecating Mode and moving to a
new std::string, but that breaks ABI of course, so that was out of
question. We can't change to a malloc/free style c-string either as
Mode is public and hence a library user could be setting this as well.
std::string implementors actually helped us out here with copy-on-write
which means that while the variable "obviously" runs out of scope here,
in reality you get the correct result as the string we work with here
comes from the configuration in which it is still valid. Such a
dependency on magic is bad of course, but its still interesting that
only python3 seems to have an issue with it…
With some silly explicit if-else assigning we can sidestep this issue
while retaining the same output for 99.99% of all users (= noone
actually configures additional compression algorithms which are also
provided by repositories…), but even for these 0.01% its just a small
change in the display as Mode can not be used for anything else.
Example: apt/aptitude uses it in its 'update' implementations in the
one-line progress at the bottom for specific items.
Closes: 781858
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The worker expects that the methods tell him when they start or finish
downloading a file. Various information pieces are passed along in this report
including the (expected) filesize. https is using a "global" struct for
reporting which made it 'reuse' incorrect values in some cases like a
non-existent InRelease fallbacking to Release{,.gpg} resulting in an incorrect
size-mismatch warning scaring and desensitizing users as well as being subject
to a race between the write_data and progress callbacks generating incorrect
progress reporting and potentially the same error message.
Other branches as well as the bugreports contain 'better' fixes making the
struct local and other sensible changes, but are larger as a result, so in
this version we opted for short diff with minimal effect above else instead.
Closes: 777565, 781509
Thanks: Robert Edmonds and Anders Kaseorg for initial patchs
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