From 5df912b162575cb9daf6702bb7f2c2a5858c0b00 Mon Sep 17 00:00:00 2001 From: fiddlosopher Date: Thu, 3 Jan 2008 21:32:32 +0000 Subject: Added optional HTML sanitization using a whitelist. When this option is specified (--sanitize-html on the command line), unsafe HTML tags will be replaced by HTML comments, and unsafe HTML attributes will be removed. This option should be especially useful for those who want to use pandoc libraries in web applications, where users will provide the input. + Main.hs: Added --sanitize-html option. + Text.Pandoc.Shared: Added stateSanitizeHTML to ParserState. + Text.Pandoc.Readers.HTML: - Added whitelists of sanitaryTags and sanitaryAttributes. - Added parsers to check these lists (and state) to see if a given tag or attribute should be counted unsafe. - Modified anyHtmlTag and anyHtmlEndTag to replace unsafe tags with comments. - Modified htmlAttribute to remove unsafe attributes. - Modified htmlScript and htmlStyle to remove these elements if unsafe. - Modified rawHtmlBlock to use anyHtmlBlockTag instead of anyHtmlTag and anyHtmlEndTag. This fixes a bug in markdown parsing, where inline tags would be included in raw HTML blocks. - Modified anyHtmlBlockTag to test for (not inline) rather than directly for block. This allows us to handle e.g. docbook in the markdown reader. - Minor tweaks in nonTitleNonHead and parseTitle. + Text.Pandoc.Readers.Markdown: - In non-strict mode use rawHtmlBlocks instead of htmlBlock. Simplified htmlBlock, since we know it's only called in strict mode. + Modified README and man pages to document new option. git-svn-id: https://pandoc.googlecode.com/svn/trunk@1166 788f1e2b-df1e-0410-8736-df70ead52e1b --- Text/Pandoc/Readers/HTML.hs | 93 +++++++++++++++++++++++++++++++++++------ Text/Pandoc/Readers/Markdown.hs | 17 ++++---- Text/Pandoc/Shared.hs | 2 + 3 files changed, 89 insertions(+), 23 deletions(-) (limited to 'Text/Pandoc') diff --git a/Text/Pandoc/Readers/HTML.hs b/Text/Pandoc/Readers/HTML.hs index 1fff4705f..42a085f63 100644 --- a/Text/Pandoc/Readers/HTML.hs +++ b/Text/Pandoc/Readers/HTML.hs @@ -75,10 +75,54 @@ blockHtmlTags = ["address", "blockquote", "center", "dir", "div", "dt", "frameset", "li", "tbody", "td", "tfoot", "th", "thead", "tr", "script"] ++ eitherBlockOrInline +sanitaryTags = ["a", "abbr", "acronym", "address", "area", "b", "big", + "blockquote", "br", "button", "caption", "center", + "cite", "code", "col", "colgroup", "dd", "del", "dfn", + "dir", "div", "dl", "dt", "em", "fieldset", "font", + "form", "h1", "h2", "h3", "h4", "h5", "h6", "hr", + "i", "img", "input", "ins", "kbd", "label", "legend", + "li", "map", "menu", "ol", "optgroup", "option", "p", + "pre", "q", "s", "samp", "select", "small", "span", + "strike", "strong", "sub", "sup", "table", "tbody", + "td", "textarea", "tfoot", "th", "thead", "tr", "tt", + "u", "ul", "var"] + +sanitaryAttributes = ["abbr", "accept", "accept-charset", + "accesskey", "action", "align", "alt", "axis", + "border", "cellpadding", "cellspacing", "char", + "charoff", "charset", "checked", "cite", "class", + "clear", "cols", "colspan", "color", "compact", + "coords", "datetime", "dir", "disabled", + "enctype", "for", "frame", "headers", "height", + "href", "hreflang", "hspace", "id", "ismap", + "label", "lang", "longdesc", "maxlength", "media", + "method", "multiple", "name", "nohref", "noshade", + "nowrap", "prompt", "readonly", "rel", "rev", + "rows", "rowspan", "rules", "scope", "selected", + "shape", "size", "span", "src", "start", + "summary", "tabindex", "target", "title", "type", + "usemap", "valign", "value", "vspace", "width"] + -- -- HTML utility functions -- +-- | Returns @True@ if sanitization is specified and the specified tag is +-- not on the sanitized tag list. +unsanitaryTag tag = do + st <- getState + if stateSanitizeHTML st && not (tag `elem` sanitaryTags) + then return True + else return False + +-- | returns @True@ if sanitization is specified and the specified attribute +-- is not on the sanitized attribute list. +unsanitaryAttribute (attr, _, _) = do + st <- getState + if stateSanitizeHTML st && not (attr `elem` sanitaryAttributes) + then return True + else return False + -- | Read blocks until end tag. blocksTilEnd tag = do blocks <- manyTill (block >>~ spaces) (htmlEndTag tag) @@ -111,20 +155,28 @@ anyHtmlTag = try $ do let ender' = if null ender then "" else " /" spaces char '>' - return $ "<" ++ tag ++ - concatMap (\(_, _, raw) -> (' ':raw)) attribs ++ ender' ++ ">" + let result = "<" ++ tag ++ + concatMap (\(_, _, raw) -> (' ':raw)) attribs ++ ender' ++ ">" + unsanitary <- unsanitaryTag tag + if unsanitary + then return $ "" + else return result anyHtmlEndTag = try $ do char '<' spaces char '/' spaces - tagType <- many1 alphaNum + tag <- many1 alphaNum spaces char '>' - return $ "" + let result = "" + unsanitary <- unsanitaryTag tag + if unsanitary + then return $ "" + else return result -htmlTag :: String -> GenParser Char st (String, [(String, String)]) +htmlTag :: String -> GenParser Char ParserState (String, [(String, String)]) htmlTag tag = try $ do char '<' spaces @@ -142,7 +194,14 @@ quoted quoteChar = do (many (noneOf [quoteChar])) return (result, [quoteChar]) -htmlAttribute = htmlRegularAttribute <|> htmlMinimizedAttribute +nullAttribute = ("", "", "") + +htmlAttribute = do + attr <- htmlRegularAttribute <|> htmlMinimizedAttribute + unsanitary <- unsanitaryAttribute attr + if unsanitary + then return nullAttribute + else return attr -- minimized boolean attribute htmlMinimizedAttribute = try $ do @@ -183,7 +242,7 @@ isBlock tag = (extractTagType tag) `elem` blockHtmlTags anyHtmlBlockTag = try $ do tag <- anyHtmlTag <|> anyHtmlEndTag - if isBlock tag then return tag else fail "not a block tag" + if not (isInline tag) then return tag else fail "not a block tag" anyHtmlInlineTag = try $ do tag <- anyHtmlTag <|> anyHtmlEndTag @@ -194,19 +253,25 @@ anyHtmlInlineTag = try $ do htmlScript = try $ do open <- string "" + st <- getState + if stateSanitizeHTML st && not ("script" `elem` sanitaryTags) + then return "" + else return $ open ++ rest ++ "" -- | Parses material between style tags. -- Style tags must be treated differently, because they can contain CSS htmlStyle = try $ do open <- string "" + st <- getState + if stateSanitizeHTML st && not ("style" `elem` sanitaryTags) + then return "" + else return $ open ++ rest ++ "" htmlBlockElement = choice [ htmlScript, htmlStyle, htmlComment, xmlDec, definition ] rawHtmlBlock = try $ do - body <- htmlBlockElement <|> anyHtmlTag <|> anyHtmlEndTag + body <- htmlBlockElement <|> anyHtmlBlockTag state <- getState if stateParseRaw state then return (RawHtml body) else return Null @@ -235,8 +300,10 @@ definition = try $ do rest <- manyTill anyChar (char '>') return $ "" -nonTitleNonHead = try $ notFollowedBy' (htmlTag "title" <|> htmlTag "/head") >> - ((rawHtmlBlock >> return ' ') <|> anyChar) +nonTitleNonHead = try $ do + notFollowedBy $ (htmlTag "title" >> return ' ') <|> + (htmlEndTag "head" >> return ' ') + (rawHtmlBlock >> return ' ') <|> anyChar parseTitle = try $ do (tag, _) <- htmlTag "title" @@ -251,7 +318,7 @@ parseHead = try $ do skipMany nonTitleNonHead contents <- option [] parseTitle skipMany nonTitleNonHead - htmlTag "/head" + htmlEndTag "head" return (contents, [], "") skipHtmlTag tag = optional (htmlTag tag) diff --git a/Text/Pandoc/Readers/Markdown.hs b/Text/Pandoc/Readers/Markdown.hs index 6455dcd9d..2d1fa7583 100644 --- a/Text/Pandoc/Readers/Markdown.hs +++ b/Text/Pandoc/Readers/Markdown.hs @@ -249,7 +249,7 @@ block = do , blockQuote , rawLaTeXEnvironment , para - , htmlBlock + , rawHtmlBlocks , plain , nullBlock ]) "block" @@ -482,15 +482,12 @@ plain = many1 inline >>= return . Plain . normalizeSpaces htmlElement = strictHtmlBlock <|> htmlBlockElement "html element" -htmlBlock = do - st <- getState - if stateStrict st - then try $ do failUnlessBeginningOfLine - first <- htmlElement - finalSpace <- many (oneOf spaceChars) - finalNewlines <- many newline - return $ RawHtml $ first ++ finalSpace ++ finalNewlines - else rawHtmlBlocks +htmlBlock = try $ do + failUnlessBeginningOfLine + first <- htmlElement + finalSpace <- many (oneOf spaceChars) + finalNewlines <- many newline + return $ RawHtml $ first ++ finalSpace ++ finalNewlines -- True if tag is self-closing isSelfClosing tag = diff --git a/Text/Pandoc/Shared.hs b/Text/Pandoc/Shared.hs index 7086ca452..477d86464 100644 --- a/Text/Pandoc/Shared.hs +++ b/Text/Pandoc/Shared.hs @@ -595,6 +595,7 @@ data ParserState = ParserState { stateParseRaw :: Bool, -- ^ Parse raw HTML and LaTeX? stateParserContext :: ParserContext, -- ^ Inside list? stateQuoteContext :: QuoteContext, -- ^ Inside quoted environment? + stateSanitizeHTML :: Bool, -- ^ Sanitize HTML? stateKeys :: KeyTable, -- ^ List of reference keys stateNotes :: NoteTable, -- ^ List of notes stateTabStop :: Int, -- ^ Tab stop @@ -614,6 +615,7 @@ defaultParserState = ParserState { stateParseRaw = False, stateParserContext = NullState, stateQuoteContext = NoQuote, + stateSanitizeHTML = False, stateKeys = [], stateNotes = [], stateTabStop = 4, -- cgit v1.2.3