Jens Petersen
11 months ago
parent
0b86371751
commit
0c9252520b
@ -0,0 +1,92 @@
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commit 5e381e3878b5da87ee7542f7e51c3c1a7fd84b89
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Author: John MacFarlane <jgm@berkeley.edu>
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Date: Tue Jun 20 13:50:13 2023 -0700
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Fix a security vulnerability in MediaBag and T.P.Class.IO.writeMedia.
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This vulnerability, discovered by Entroy C, allows users to write
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arbitrary files to any location by feeding pandoc a specially crafted
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URL in an image element. The vulnerability is serious for anyone
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using pandoc to process untrusted input. The vulnerability does
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not affect pandoc when run with the `--sandbox` flag.
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--- pandoc-2.14.0.3/src/Text/Pandoc/Class/IO.hs.orig 2021-06-11 07:26:17.000000000 +0800
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+++ pandoc-2.14.0.3/src/Text/Pandoc/Class/IO.hs 2024-03-22 16:39:03.445837785 +0800
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@@ -48,7 +48,7 @@
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import Network.HTTP.Client.TLS (mkManagerSettings)
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import Network.HTTP.Types.Header ( hContentType )
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import Network.Socket (withSocketsDo)
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-import Network.URI (unEscapeString)
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+import Network.URI (URI(..), parseURI)
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import System.Directory (createDirectoryIfMissing)
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import System.Environment (getEnv)
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import System.FilePath ((</>), takeDirectory, normalise)
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@@ -119,11 +119,11 @@
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openURL :: (PandocMonad m, MonadIO m) => Text -> m (B.ByteString, Maybe MimeType)
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openURL u
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- | Just u'' <- T.stripPrefix "data:" u = do
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- let mime = T.takeWhile (/=',') u''
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- let contents = UTF8.fromString $
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- unEscapeString $ T.unpack $ T.drop 1 $ T.dropWhile (/=',') u''
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- return (decodeLenient contents, Just mime)
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+ | Just (URI{ uriScheme = "data:",
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+ uriPath = upath }) <- parseURI (T.unpack u) = do
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+ let (mime, rest) = break (== '.') upath
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+ let contents = UTF8.fromString $ drop 1 rest
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+ return (decodeLenient contents, Just (T.pack mime))
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| otherwise = do
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let toReqHeader (n, v) = (CI.mk (UTF8.fromText n), UTF8.fromText v)
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customHeaders <- map toReqHeader <$> getsCommonState stRequestHeaders
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--- pandoc-2.14.0.3/src/Text/Pandoc/MediaBag.hs.orig 2021-06-19 04:15:43.000000000 +0800
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+++ pandoc-2.14.0.3/src/Text/Pandoc/MediaBag.hs 2024-03-22 16:33:37.600005389 +0800
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@@ -33,7 +33,7 @@
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import Data.Text (Text)
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import qualified Data.Text as T
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import Data.Digest.Pure.SHA (sha1, showDigest)
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-import Network.URI (URI (..), parseURI)
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+import Network.URI (URI (..), parseURI, isURI, unEscapeString)
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data MediaItem =
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MediaItem
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@@ -52,9 +52,12 @@
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instance Show MediaBag where
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show bag = "MediaBag " ++ show (mediaDirectory bag)
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--- | We represent paths with /, in normalized form.
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+-- | We represent paths with /, in normalized form. Percent-encoding
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+-- is resolved.
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canonicalize :: FilePath -> Text
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-canonicalize = T.replace "\\" "/" . T.pack . normalise
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+canonicalize fp
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+ | isURI fp = T.pack fp
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+ | otherwise = T.replace "\\" "/" . T.pack . normalise . unEscapeString $ fp
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-- | Delete a media item from a 'MediaBag', or do nothing if no item corresponds
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-- to the given path.
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@@ -77,17 +80,18 @@
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, mediaContents = contents
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, mediaMimeType = mt }
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fp' = canonicalize fp
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+ fp'' = T.unpack fp'
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uri = parseURI fp
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- newpath = if isRelative fp
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+ newpath = if isRelative fp''
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&& isNothing uri
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- && ".." `notElem` splitPath fp
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- then T.unpack fp'
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+ && not (".." `T.isInfixOf` fp')
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+ then fp''
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else showDigest (sha1 contents) <> "." <> ext
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- fallback = case takeExtension fp of
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- ".gz" -> getMimeTypeDef $ dropExtension fp
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- _ -> getMimeTypeDef fp
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+ fallback = case takeExtension fp'' of
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+ ".gz" -> getMimeTypeDef $ dropExtension fp''
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+ _ -> getMimeTypeDef fp''
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mt = fromMaybe fallback mbMime
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- path = maybe fp uriPath uri
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+ path = maybe fp'' (unEscapeString . uriPath) uri
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ext = case takeExtension path of
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'.':e -> e
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_ -> maybe "" T.unpack $ extensionFromMimeType mt
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@ -0,0 +1,49 @@
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commit eddedbfc14916aa06fc01ff04b38aeb30ae2e625
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Author: John MacFarlane <jgm@berkeley.edu>
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Date: Thu Jul 20 09:26:38 2023 -0700
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Fix new variant of the vulnerability in CVE-2023-35936.
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Guilhem Moulin noticed that the fix to CVE-2023-35936 was incomplete.
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An attacker could get around it by double-encoding the malicious
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extension to create or override arbitrary files.
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$ echo '' >b.md
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$ .cabal/bin/pandoc b.md --extract-media=bar
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<p><img
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src="bar/2a0eaa89f43fada3e6c577beea4f2f8f53ab6a1d.lua+%2f%2e%2e%2f%2e%2e%2fb%2elua" /></p>
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$ cat b.lua
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print "hello"
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$ find bar
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bar/
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bar/2a0eaa89f43fada3e6c577beea4f2f8f53ab6a1d.lua+
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This commit adds a test case for this more complex attack and fixes
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the vulnerability. (The fix is quite simple: if the URL-unescaped
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filename or extension contains a '%', we just use the sha1 hash of the
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contents as the canonical name, just as we do if the filename contains
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'..'.)
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--- pandoc-2.14.0.3/src/Text/Pandoc/MediaBag.hs.orig 2024-03-22 16:40:07.874200094 +0800
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+++ pandoc-2.14.0.3/src/Text/Pandoc/MediaBag.hs 2024-03-22 16:42:13.289905373 +0800
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@@ -85,16 +85,17 @@
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newpath = if isRelative fp''
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&& isNothing uri
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&& not (".." `T.isInfixOf` fp')
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+ && '%' `notElem` fp''
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then fp''
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- else showDigest (sha1 contents) <> "." <> ext
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+ else showDigest (sha1 contents) <> ext
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fallback = case takeExtension fp'' of
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".gz" -> getMimeTypeDef $ dropExtension fp''
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_ -> getMimeTypeDef fp''
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mt = fromMaybe fallback mbMime
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path = maybe fp'' (unEscapeString . uriPath) uri
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ext = case takeExtension path of
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- '.':e -> e
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- _ -> maybe "" T.unpack $ extensionFromMimeType mt
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+ '.':e | '%' `notElem` e -> '.':e
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+ _ -> maybe "" (\x -> '.':T.unpack x) $ extensionFromMimeType mt
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-- | Lookup a media item in a 'MediaBag', returning mime type and contents.
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