From: Zooko O'Whielacronx Date: Fri, 13 Feb 2009 05:16:21 +0000 (-0700) Subject: docs: known_issues.txt: my version of #615, remove "issue numbers", edits, move tahoe... X-Git-Tag: allmydata-tahoe-1.3.0~12 X-Git-Url: https://git.rkrishnan.org/?a=commitdiff_plain;h=de8e72e27bcf6366430d04acc3eae5c498839a5f;p=tahoe-lafs%2Ftahoe-lafs.git docs: known_issues.txt: my version of #615, remove "issue numbers", edits, move tahoe-1.1.0 issues to historical --- diff --git a/docs/historical/historical_known_issues.txt b/docs/historical/historical_known_issues.txt index 88d76c06..cd76ef8c 100644 --- a/docs/historical/historical_known_issues.txt +++ b/docs/historical/historical_known_issues.txt @@ -10,11 +10,114 @@ Tahoe-LAFS can be found at: http://allmydata.org/source/tahoe/trunk/docs/known_issues.txt +== issues in Tahoe v1.1.0, released 2008-06-11 == + +(Tahoe v1.1.0 was superceded by v1.2.0 which was released 2008-07-21, +and then by v1.3.0 which was released 2009-02-13.) + +=== more than one file can match an immutable file cap === + +In Tahoe v1.0 and v1.1, a flaw in the cryptographic integrity check +makes it possible for the original uploader of an immutable file to +produce more than one immutable file matching the same capability, so +that different downloads using the same capability could result in +different files. This flaw can be exploited only by the original +uploader of an immutable file, which means that it is not a severe +vulnerability: you can still rely on the integrity check to make sure +that the file you download with a given capability is a file that the +original uploader intended. The only issue is that you can't assume +that every time you use the same capability to download a file you'll +get the same file. + +==== how to manage it ==== + +This was fixed in Tahoe v1.2.0, released 2008-07-21, under ticket +#491. Upgrade to that release of Tahoe and then you can rely on the +property that there is only one file that you can download using a +given capability. If you are still using Tahoe v1.0 or v1.1, then +remember that the original uploader could produce multiple files that +match the same capability, so for example if someone gives you a +capability, and you use it to download a file, and you give that +capability to your friend, and he uses it to download a file, you and +your friend could get different files. + + +=== server out of space when writing mutable file === + +If a v1.0 or v1.1 storage server runs out of disk space or is +otherwise unable to write to its local filesystem, then problems can +ensue. For immutable files, this will not lead to any problem (the +attempt to upload that share to that server will fail, the partially +uploaded share will be deleted from the storage server's "incoming +shares" directory, and the client will move on to using another +storage server instead). + +If the write was an attempt to modify an existing mutable file, +however, a problem will result: when the attempt to write the new +share fails (e.g. due to insufficient disk space), then it will be +aborted and the old share will be left in place. If enough such old +shares are left, then a subsequent read may get those old shares and +see the file in its earlier state, which is a "rollback" failure. +With the default parameters (3-of-10), six old shares will be enough +to potentially lead to a rollback failure. + +==== how to manage it ==== + +Make sure your Tahoe storage servers don't run out of disk space. +This means refusing storage requests before the disk fills up. There +are a couple of ways to do that with v1.1. + +First, there is a configuration option named "sizelimit" which will +cause the storage server to do a "du" style recursive examination of +its directories at startup, and then if the sum of the size of files +found therein is greater than the "sizelimit" number, it will reject +requests by clients to write new immutable shares. + +However, that can take a long time (something on the order of a minute +of examination of the filesystem for each 10 GB of data stored in the +Tahoe server), and the Tahoe server will be unavailable to clients +during that time. + +Another option is to set the "readonly_storage" configuration option +on the storage server before startup. This will cause the storage +server to reject all requests to upload new immutable shares. + +Note that neither of these configurations affect mutable shares: even +if sizelimit is configured and the storage server currently has +greater space used than allowed, or even if readonly_storage is +configured, servers will continue to accept new mutable shares and +will continue to accept requests to overwrite existing mutable shares. + +Mutable files are typically used only for directories, and are usually +much smaller than immutable files, so if you use one of these +configurations to stop the influx of immutable files while there is +still sufficient disk space to receive an influx of (much smaller) +mutable files, you may be able to avoid the potential for "rollback" +failure. + +A future version of Tahoe will include a fix for this issue. Here is +[http://allmydata.org/pipermail/tahoe-dev/2008-May/000630.html the +mailing list discussion] about how that future version will work. + + +=== pyOpenSSL/Twisted defect causes false alarms in tests === + +The combination of Twisted v8.0 or Twisted v8.1 with pyOpenSSL v0.7 +causes the Tahoe v1.1 unit tests to fail, even though the behavior of +Tahoe itself which is being tested is correct. + +==== how to manage it ==== + +If you are using Twisted v8.0 or Twisted v8.1 and pyOpenSSL v0.7, then +please ignore ERROR "Reactor was unclean" in test_system and +test_introducer. Upgrading to a newer version of Twisted or pyOpenSSL +will cause those false alarms to stop happening (as will downgrading +to an older version of either of those packages). == issues in Tahoe v1.0.0, released 2008-03-25 == (Tahoe v1.0 was superceded by v1.1 which was released 2008-06-11.) -=== issue 6: server out of space when writing mutable file === +=== server out of space when writing mutable file === In addition to the problems caused by insufficient disk space described above, v1.0 clients which are writing mutable files when the @@ -28,7 +131,7 @@ write to their local filesystem (including that there is space available) as described in "issue 1" above. -=== issue 5: server out of space when writing immutable file === +=== server out of space when writing immutable file === Tahoe v1.0 clients are using v1.0 servers which are unable to write to their filesystem during an immutable upload will correctly detect the @@ -45,7 +148,7 @@ always able to write to their local filesystem (including that there is space available) as described in "issue 1" above. -=== issue 4: large directories or mutable files of certain sizes === +=== large directories or mutable files of certain sizes === If a client attempts to upload a large mutable file with a size greater than about 3,139,000 and less than or equal to 3,500,000 bytes @@ -72,7 +175,7 @@ to v1.1 but the client is still v1.0 then the client will still suffer this failure.) -=== issue 3: uploading files greater than 12 GiB === +=== uploading files greater than 12 GiB === If a Tahoe v1.0 client uploads a file greater than 12 GiB in size, the file will be silently corrupted so that it is not retrievable, but the client will think @@ -87,7 +190,7 @@ Tahoe storage grid. Tahoe v1.1 clients will refuse to upload files larger than limitation so that larger files can be uploaded. -=== issue 2: pycryptopp defect resulting in data corruption === +=== pycryptopp defect resulting in data corruption === Versions of pycryptopp earlier than pycryptopp-0.5.0 had a defect which, when compiled with some compilers, would cause AES-256 @@ -104,33 +207,3 @@ Tahoe v1.0 {{{misc/dependencies}}} directory, cd into the resulting {{{pycryptopp-0.3.0}}} directory, and execute {{{python ./setup.py test}}}. If the tests pass, then your compiler does not trigger this failure. - - -=== issue 1: potential disclosure of a file through embedded -hyperlinks or JavaScript in that file === - -If there is a file stored on a Tahoe storage grid, and that file gets -downloaded and displayed in a web browser, then JavaScript or -hyperlinks within that file can leak the capability to that file to a -third party, which means that third party gets access to the file. - -If there is JavaScript in the file, then it could deliberately leak -the capability to the file out to some remote listener. - -If there are hyperlinks in the file, and they get followed, then -whichever server they point to receives the capability to the -file. Note that IMG tags are typically followed automatically by web -browsers, so being careful which hyperlinks you click on is not -sufficient to prevent this from happening. - -==== how to manage it ==== - -For future versions of Tahoe, we are considering ways to close off -this leakage of authority while preserving ease of use -- the -discussion of this issue is ticket #127. - -For the present, a good work-around is that if you want to store and -view a file on Tahoe and you want that file to remain private, then -remove from that file any hyperlinks pointing to other people's -servers and remove any JavaScript unless you are sure that the -JavaScript is not written to maliciously leak access. diff --git a/docs/known_issues.txt b/docs/known_issues.txt index d4287956..3e582c4e 100644 --- a/docs/known_issues.txt +++ b/docs/known_issues.txt @@ -10,29 +10,32 @@ Tahoe-LAFS can be found at http://allmydata.org/source/tahoe/trunk/docs/historical/historical_known_issues.txt -== issues in Tahoe v1.3.0, not yet released == +== issues in Tahoe v1.3.0, released 2009-02-13 == -=== unauthorized access by JavaScript in other tabs/frames === -If you use a web browser to view a javascript-bearing HTML document that is -served from a Tahoe node, then that javascript program can learn the access -caps for any other file or directory, served by the same Tahoe node, that you -are currently viewing in other tabs or frames. This is a consequence of the -common "Same Origin Policy" as applied to javascript and inter-frame access, -in which the browser mistakenly believes that two documents retrieved from -the same server should have access to each others DOM state. Note that some -browsers are quite enthusiastic about interpreting