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2018-08-20clear alternative URIs for mirror:// between steps (CVE-2018-0501)David Kalnischkies
APT in 1.6 saw me rewriting the mirror:// transport method, which works comparable to the decommissioned httpredir.d.o "just" that apt requests a mirror list and performs all the redirections internally with all the bells like parallel download and automatic fallback (more details in the apt-transport-mirror manpage included in the 1.6 release). The automatic fallback is the problem here: The intend is that if a file fails to be downloaded (e.g. because the mirror is offline, broken, out-of-sync, …) instead of erroring out the next mirror in the list is contacted for a retry of the download. Internally the acquire process of an InRelease file (works with the Release/Release.gpg pair, too) happens in steps: 1) download file and 2) verify file, both handled as URL requests passed around. Due to an oversight the fallbacks for the first step are still active for the second step, so that the successful download from another mirror stands in for the failed verification… *facepalm* Note that the attacker can not judge by the request arriving for the InRelease file if the user is using the mirror method or not. If entire traffic is observed Eve might be able to observe the request for a mirror list, but that might or might not be telling if following requests for InRelease files will be based on that list or for another sources.list entry not using mirror (Users have also the option to have the mirror list locally (via e.g. mirror+file://) instead of on a remote host). If the user isn't using mirror:// for this InRelease file apt will fail very visibly as intended. (The mirror list needs to include at least two mirrors and to work reliably the attacker needs to be able to MITM all mirrors in the list. For remotely accessed mirror lists this is no limitation as the attacker is in full control of the file in that case) Fixed by clearing the alternatives after a step completes (and moving a pimpl class further to the top to make that valid compilable code). mirror:// is at the moment the only method using this code infrastructure (for all others this set is already empty) and the only method-independent user so far is the download of deb files, but those are downloaded and verified in a single step; so there shouldn't be much opportunity for regression here even through a central code area is changed. Upgrade instructions: Given all apt-based frontends are affected, even additional restrictions like signed-by are bypassed and the attack in progress is hardly visible in the progress reporting of an update operation (the InRelease file is marked "Ign", but no fallback to "Release/Release.gpg" is happening) and leaves no trace (expect files downloaded from the attackers repository of course) the best course of action might be to change the sources.list to not use the mirror family of transports ({tor+,…}mirror{,+{http{,s},file,…}}) until a fixed version of the src:apt packages are installed. Regression-Of: 355e1aceac1dd05c4c7daf3420b09bd860fd169d, 57fa854e4cdb060e87ca265abd5a83364f9fa681 LP: #1787752
2018-07-06Use cheaper entropy source for randomizing items to fetchJulian Andres Klode
The random_device fails if not enough entropy is available. We do not need high-quality entropy here, though, so let's switch to a seed based on the current time in nanoseconds, XORed with the PID.
2018-05-28Don't show acquire warning for "hidden" componentsDavid Kalnischkies
Commit d7c92411dc1f4c6be098d1425f9c1c075e0c2154 introduced a warning for non-existent files from components not mentioned in Components to hint users at a mispelling or the disappearance of a component. The debian-installer subcomponent isn't actively advertised in the Release file through, so if apt ends up in acquiring a file which doesn't exist for this component (like Translation files) apt would produce a warning: W: Skipping acquire of configured file 'main/debian-installer/i18n/Translation-en' as repository 'http://deb.debian.org/debian buster InRelease' doesn't have the component 'main/debian-installer' (component misspelt in sources.list?) We prevent this in the future by checking if any file exists from this component which results in the warning to be produced still for the intended cases and silence it on the d-i case. This could potentially cause the warning not to be produced in cases it should be if some marginal file remains, but as this message is just a hint and the setup a bit pathological lets ignore it for now. There is also the possibility of having no file present as they would all be 0-length files and being a "hidden" component, but that would be easy to workaround from the repository side and isn't really actively used at the moment in the wild. Closes: #879591
2018-05-11Don't force the same mirror for by-hash URIsDavid Kalnischkies
Downloading from the same mirror we got a Release file from makes sense for non-unique URIs as their content changes between mirror states, but if we ask for an index via by-hash we can be sure that we either get the file we wanted or a 404 for which we can perform a fallback for which allows us to pull indexes from different mirror in parallel.
2018-05-11Handle by-hash URI construction more centrallyDavid Kalnischkies
Individual items shouldn't concern themselves with these alternative locations, we can deal with this more efficiently within the infrastructure created for other alternative URIs now avoiding the need to implement this in each item.
2018-05-11Drop alternative URIs we got a hash-based fail fromDavid Kalnischkies
If we got a file but it produced a hash error, mismatched size or similar we shouldn't fallback to alternative URIs as they likely result in the same error. If we can we should instead use another mirror. We used to be a lot stricter by stopping all trys for this file if we got a non-404 (or a hash-based) failure, but that is too hard as we really want to try other mirrors (if we have them) in the hope that they have the expected and correct files.
2018-05-07Remove obsolete RCS keywordsGuillem Jover
Prompted-by: Jakub Wilk <jwilk@debian.org>
2018-05-05Fix various typos reported by spellcheckersDavid Kalnischkies
Reported-By: codespell & spellintian Gbp-Dch: Ignore
2018-02-19Merge branch 'pu/not-valid-before' into 'master'Julian Andres Klode
Check that Date of Release file is not in the future See merge request apt-team/apt!3
2018-02-19Check that Date of Release file is not in the futureJulian Andres Klode
By restricting the Date field to be in the past, an attacker cannot just create a repository from the future that would be accepted as a valid update for a repository. This check can be disabled by Acquire::Check-Date set to false. This will also disable Check-Valid-Until and any future date related checking, if any - the option means: "my computers date cannot be trusted." Modify the tests to allow repositories to be up to 10 hours in the future, so we can keep using hours there to simulate time changes.
2018-02-19ensure correct file permissions for auxfilesDavid Kalnischkies
The interesting takeaway here is perhaps that 'chmod +w' is effected by the umask – obvious in hindsight of course. The usual setup helps with hiding that applying that recursively on all directories (and files) isn't correct. Ensuring files will not be stored with the wrong permissions even if in strange umask contexts is trivial in comparison. Fixing the test also highlighted that it wasn't bulletproof as apt will automatically fix the permissions of the directories it works with, so for this test we actually need to introduce a shortcut in the code. Reported-By: Ubuntu autopkgtest CI
2018-01-19allow the apt/lists/auxfiles/ directory to be missingDavid Kalnischkies
apt 1.6~alpha6 introduced aux requests to revamp the implementation of a-t-mirror. This already included the potential of running as non-root, but the detection wasn't complete resulting in errors or could produce spurious warnings along the way if the directory didn't exist yet. References: ef9677831f62a1554a888ebc7b162517d7881116 Closes: 887624
2018-01-17Introduce inrelease-path option for sources.listJulian Andres Klode
Allow specifying an alternative path to the InRelease file, so you can have multiple versions of a repository, for example. Enabling this option disables fallback to Release and Release.gpg, so setting it to InRelease can be used to ensure that only that will be tried. We add two test cases: One for checking that it works, and another for checking that the fallback does not happen. Closes: #886745
2018-01-03allow a method to request auxiliary filesDavid Kalnischkies
If a method needs a file to operate like e.g. mirror needs to get a list of mirrors before it can redirect the the actual requests to them. That could easily be solved by moving the logic into libapt directly, but by allowing a method to request other methods to do something we can keep this logic contained in the method and allow e.g. also methods which perform binary patching or similar things. Previously they would need to implement their own acquire system inside the existing one which in all likelyhood will not support the same features and methods nor operate with similar security compared to what we have already running 'above' the requesting method. That said, to avoid methods producing conflicts with "proper" files we are downloading a new directory is introduced to keep the auxiliary files in. [The message magic number 351 is a tribute to the german Grundgesetz article 35 paragraph 1 which defines that all authorities of the state(s) help each other on request.]
2017-12-14remove pointless APT_PURE from void functionsDavid Kalnischkies
Earlier gcc versions used to complain that you should add them althrough there isn't a lot of point to it if you think about it, but now gcc (>= 8) complains about the attribute being present. warning: ‘pure’ attribute on function returning ‘void’ [-Wattributes] Reported-By: gcc -Wattributes Gbp-Dch: Ignore
2017-12-13implement fallback to alternative URIs for all itemsDavid Kalnischkies
For deb files we always supported falling back from one server to the other if one failed to download the deb, but that was hardwired in the handling of this specific item. Moving this alongside the retry infrastructure we can implement it for all items and allow methods to use this as well by providing additional URIs in a redirect.
2017-12-13give the methods more metadata about the files to acquireDavid Kalnischkies
We have quite a bit of metadata available for the files we acquire, but the methods weren't told about it and got just the URI. That is indeed fine for most, but to avoid methods trying to parse the metadata out of the provided URIs (and fail horribly in edgecases) we can just as well be nice and tell them stuff directly.
2017-12-13implement Acquire::Retries support for all itemsDavid Kalnischkies
Moving the Retry-implementation from individual items to the worker implementation not only gives every file retry capability instead of just a selected few but also avoids needing to implement it in each item (incorrectly).
2017-12-13deprecate the single-line deprecation ignoring macroDavid Kalnischkies
gcc has problems understanding this construct and additionally thinks it would produce multiple lines and stuff, so to keep using it isn't really worth it for the few instances we have: We can just write the long form there which works better. Reported-By: gcc Gbp-Dch: Ignore
2017-12-13if insecure repo is allowed continue on all http errorsDavid Kalnischkies
If a InRelease file fails to download with a non-404 error we assumed there is some general problem with repository like a webportal or your are blocked from access (wrong auth, Tor, …). Turns out some server like S3 return 403 if a file doesn't exist. Allowing this in general seems like a step backwards as 403 is a reasonable response if auth failed, so failing here seems better than letting those users run into problems. What we can do is show our insecure warnings through and allow the failures for insecure repos: If the repo is signed it is easy to add an InRelease file and if not you are setup for trouble anyhow. References: cbbf185c3c55effe47f218a07e7b1f324973a8a6
2017-10-28use store: instead of gzip: to open local changelogsDavid Kalnischkies
Regression-Of: cc1f94c95373670fdfdb8e2d6cf9125181f7df0c
2017-08-24Replace APT_CONST with APT_PURE everywhereJulian Andres Klode
As a follow up to the last commit, let's replace APT_CONST with APT_PURE everywhere to clean stuff up.
2017-07-26don't move failed pdiff indexes out of partialDavid Kalnischkies
The comment says this is intended, but looking at the history reveals that the comment comes from a different era. Nowadays we don't really need it anymore (and even back then it was disputeable) as we haven't used that file for our update in the end and nothing really needs this file after the update. Triggered is this by 188f297a2af4c15cb1d502360d1e478644b5b810 which moves various error conditions forward including this code expecting the file to exist – but it doesn't need to as download could have failed. We could fix that by simple checking if the file exists and only stage it if it does, but instead we don't stage it and instead even rename it out of the way with our conventional FAILED name (if it exists). That restores support for partial mirrors (= in this case mirrors which don't ship pdiff files). Note that apt heals itself even if only such a mirror is used as the update is successful even if that error is shown. Closes: 869425
2017-07-26don't try to rename failed pdiff patches twiceDavid Kalnischkies
RenameOnError does the rename already, so the check for existence will always fail making this some completely harmles but also completely pointless two lines of code we are better of removing. Gbp-Dch: Ignore
2017-07-17Merge pull request Debian/apt#44 from willismonroe/patch-1Julian Andres Klode
Minor grammar fix [jak@d.o: Fixed up po/]
2017-07-12Reformat and sort all includes with clang-formatJulian Andres Klode
This makes it easier to see which headers includes what. The changes were done by running git grep -l '#\s*include' \ | grep -E '.(cc|h)$' \ | xargs sed -i -E 's/(^\s*)#(\s*)include/\1#\2 include/' To modify all include lines by adding a space, and then running ./git-clang-format.sh.
2017-07-12Drop cacheiterators.h includeJulian Andres Klode
Including cacheiterators.h before pkgcache.h fails because pkgcache.h depends on cacheiterators.h.
2017-07-07don't expect more downloads from failed transactionsDavid Kalnischkies
Progress only shows if we have an idea of how much files we will acquire, but if a transaction fails before we have got an idea we ended up never showing progress even through we know that a failed transaction will not download additional files.
2017-06-28allow frontends to override releaseinfo change behaviourDavid Kalnischkies
Having messages being printed on the error stack and confirm them by commandline flags is an okayish first step, but some frontends will probably want to have a more interactive feeling here with a proper question the user can just press yes/no for as for some frontends a commandline flag makes no sense…
2017-06-28show a Release-Notes URI if infos were changedDavid Kalnischkies
This gives the repository owner a chance to explain why this change was needed – e.g. explaining the organisational changes or simply detailing the changes in the new release made. Note that this URI is also shown if the change is accepted, so it also draws attention to release notes of minor updates (if users watch apt output closely).
2017-06-28error in update on Release information changesDavid Kalnischkies
The value of Origin, Label, Codename and co can be used in user configuration from apts own pinning to unattended upgrades. A repository changing this values can therefore have serious effects on the behaviour of apt and other tools using these values. In a first step we will generate error messages for these changes now explaining the need for explicit confirmation and provide config options and commandline flags to accept them.
2017-06-26fail InRelease on non-404 HTTP errorcodesDavid Kalnischkies
There are very many HTTP errorcodes which indicate that the repository isn't available at the moment or the connection has some kind of problem. Given that we do not require Release files the result was that these errors were ignored and the user presented with a message like "Repository is no longer signed" which sends the user in the wrong direction. Instead of trying to figure out which http errorcodes indicate a global problem we accept only 404 for ignoring and consider all the rest as hard errors now causing us to stop instantly after the InRelease file and print the errorcode (with short description from server) received.
2017-06-26show .diff/Index properly as ignored if we fallbackDavid Kalnischkies
Moving the code responsible for parsing the Index file from ::Done into the slightly earlier ::VerifyDone allows us to still "fail" the download if we can't make use of the Index for whatever reason, so that the progress log correctly displays "Ign" instead of "Get" for the file. This also makes quiet a few debug messages proper error messages (but those are still hidden by default for Ign lines).
2017-06-26warn if an expected file can't be acquiredDavid Kalnischkies
If we couldn't find an entry for a Sources file we would generate an error while for a Packages file we would silently skip it due to assuming it is missing because it is empty. We can do better by checking if the repository declares that it supports a component we want to get the file from and if not say so and hint at the user making a typo. An example were this helps is mozilla.debian.net which dropped the firefox-aurora component (as upstream did) meaning no upgrades until the user notices manually that the repository doesn't provide packages anymore. With this commit warnings are raised hopefully causing the user to investigate what is wrong (sooner).
2017-06-22Minor grammar fixM. Willis Monroe
Modified the wording of an error message when a repository no longer has a release file.
2017-03-13Fix mistake in CHANGEPATH comment exampleJulian Andres Klode
It says SRCNAME_SRCVER, but the example just gives the SRCVER part. Reported-By: Nishanth Aravamudan (nacc) in #ubuntu-devel
2017-01-19fix various typos reported by spellintianDavid Kalnischkies
Most of them in (old) code comments. The two instances of user visible string changes the po files of the manpages are fixed up as well. Gbp-Dch: Ignore Reported-By: spellintian
2016-11-25get pdiff files from the same mirror as the indexDavid Kalnischkies
In ad9416611ab83f7799f2dcb4bf7f3ef30e9fe6f8 we fall back to asking the original mirror (e.g. a redirector) if we do not get the expected result. This works for the indexes, but patches are a different beast and much simpler. Adding this fallback code here seems like overkill as they are usually right along their Index file, so actually forward the relevant settings to the patch items which fixes pdiff support combined with a redirector and partial mirrors as in such a situation the pdiff patches would be 404 and the complete index would be downloaded.
2016-11-11show distribution mismatch for changed codenamesDavid Kalnischkies
We have the last Release file around for other checks, so its trivial to look if the new Release file contains a new codename (e.g. the user has "testing" in the sources and it flipped from stretch to buster). Such a change can be okay and expected, but also be a hint of problems, so a warning if we see it happen seems okay. We can only print it once anyhow and frontends and co are likely to ignore/hide it.
2016-11-11don't warn if untransformed distribution matchesDavid Kalnischkies
A suite or codename entry in the Release file is checked against the distribution field in the sources.list entry that lead to the download of that Release file. This distribution entry can contain slashes in the distribution field: deb http://security.debian.org/debian wheezy/updates main However, the Release file may only contain "wheezy" in the Codename field and not "wheezy/updates". So a transformation needs to take place that removes the last / and everything that comes after (e.g. "/updates"). This fails, however, for valid cases like a reprepro snapshot where the given Codename contains slashes but is perfectly fine and doesn't need to be transformed. Since that transformation is essentially just a workaround for special cases like the security repository, it should be checked if the literal Codename without any transformations happened is valid and only if isn't the dist should be checked against the transformated one. This way special cases like security.debian.org are handled and reprepro snapshots work too. The initial patch was taken as insperationto move whole transformation to CheckDist() which makes this method more accepting & easier to use (but according to codesearch.d.n we are the only users anyhow). Thanks: Lukas Anzinger for initial patch Closes: 644610
2016-11-09rename Checksum-FileSize to Filesize in hashsum mismatchDavid Kalnischkies
Some people do not recognize the field value with such an arcane name and/or expect it to refer to something different (e.g. #839257). We can't just rename it internally as its an avoidance strategy as such fieldname existed previously with less clear semantics, but we can spare the general public from this implementation detail.
2016-11-02keep Release.gpg on untrusted to trusted IMS-HitDavid Kalnischkies
A user relying on the deprecated behaviour of apt-get to accept a source with an unknown pubkey to install a package containing the key expects that the following 'apt-get update' causes the source to be considered as trusted, but in case the source hadn't changed in the meantime this wasn't happening: The source kept being untrusted until the Release file was changed. This only effects sources not using InRelease and only apt-get, the apt binary downright refuses this course of actions, but it is a common way of adding external sources. Closes: 838779
2016-09-02acquire: Use priority queues and a 3 stage pipeline designJulian Andres Klode
Employ a priority queue instead of a normal queue to hold the items; and only add items to the running pipeline if their priority is the same or higher than the priority of items in the queue. The priorities are designed for a 3 stage pipeline system: In stage 1, all Release files and .diff/Index files are fetched. This allows us to determine what files remain to be fetched, and thus ensures a usable progress reporting. In stage 2, all Pdiff patches are fetched, so we can apply them in parallel with fetching other files in stage 3. In stage 3, all other files are fetched (complete index files such as Contents, Packages). Performance improvements, mainly from fetching the pdiff patches before complete files, so they can be applied in parallel: For the 01 Sep 2016 03:35:23 UTC -> 02 Sep 2016 09:25:37 update of Debian unstable and testing with Contents and appstream for amd64 and i386, update time reduced from 37 seconds to 24-28 seconds. Previously, apt would first download new DEP11 icon tarballs and metadata files, causing the CPU to be idle. By fetching the diffs in stage 2, we can now patch our contents and Packages files while we are downloading the DEP11 stuff.
2016-08-29randomize acquire order for same type index filesDavid Kalnischkies
Without randomizing the order in which we download the index files we leak needlessly information to the mirrors of which architecture is native or foreign on this system. More importantly, we leak the order in which description translations will be used which in most cases will e.g. have the native tongue first. Note that the leak effect in practice is limited as apt detects if a file it wants to download is already available in the latest version from a previous download and does not query the server in such cases. Combined with the fact that Translation files are usually updated infrequently and not all at the same time, so a mirror can never be sure if it got asked about all files the user wants.
2016-08-27Merge branch 'portability/freebsd'Julian Andres Klode
2016-08-26Make root group configurable via ROOT_GROUPJulian Andres Klode
This is needed on BSD where root's default group is wheel, not root.
2016-08-26changelog: Respect Dir setting for local changelog gettingJulian Andres Klode
This fixes issues with chroots, but the goal here was to get the test suite working on systems without dpkg.
2016-08-26Make directory paths configurableJulian Andres Klode
This allows other vendors to use different paths, or to build your own APT in /opt for testing. Note that this uses + 1 in some places, as the paths we receive are absolute, but we need to strip of the initial /.
2016-08-26Use C locale instead of C.UTF-8 for protocol stringsJulian Andres Klode
The C.UTF-8 locale is not portable, so we need to use C, otherwise we crash on other systems. We can use std::locale::classic() for that, which might also be a bit cheaper than using locale("C").
2016-08-24do fail on weakhash/loop earlier in acquireDavid Kalnischkies
The bugreport shows a segfault caused by the code not doing the correct magical dance to remove an item from inside a queue in all cases. We could try hard to fix this, but it is actually better and also easier to perform these checks (which cause instant failure) earlier so that they haven't entered queue(s) yet, which in return makes cleanup trivial. The result is that we actually end up failing "too early" as if we wouldn't be careful download errors would be logged before that process was even started. Not a problem for the acquire system, but likely to confuse users and programs alike if they see the download process producing errors before apt was technically allowed to do an acquire (it didn't, so no violation, but it looks like it to the untrained eye). Closes: 835195