api: sanitize raw markdown content (#5907)

Fixed a security issue reported by bluebird.

go.sum

@@ -21,6 +21,7 @@ github.com/beorn7/perks v0.0.0-20180321164747-3a771d992973/go.mod h1:Dwedo/Wpr24
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@@ -38,6 +39,7 @@ github.com/cpuguy83/go-md2man/v2 v2.0.0-20190314233015-f79a8a8ca69d h1:U+s90UTSY
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@@ -79,6 +81,7 @@ github.com/go-macaron/toolbox v0.0.0-20190813233741-94defb8383c6/go.mod h1:YFNJ/
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@@ -90,6 +93,7 @@ github.com/gogs/go-gogs-client v0.0.0-20190710002546-4c3c18947c15 h1:tgEyCCe4+o8
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@@ -104,6 +108,7 @@ github.com/golang/snappy v0.0.0-20180518054509-2e65f85255db/go.mod h1:/XxbfmMg8l
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@@ -115,11 +120,13 @@ github.com/google/pprof v0.0.0-20181206194817-3ea8567a2e57/go.mod h1:zfwlbNMJ+OI
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@@ -130,6 +137,7 @@ github.com/json-iterator/go v1.1.7 h1:KfgG9LzI+pYjr4xvmz/5H4FXjokeP+rlHLhv3iH62F
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@@ -139,8 +147,10 @@ github.com/klauspost/cpuid v1.2.1 h1:vJi+O/nMdFt0vqm8NZBI6wzALWdA2X+egi0ogNyrC/w
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@@ -155,6 +165,7 @@ github.com/mattn/go-isatty v0.0.10/go.mod h1:qgIWMr58cqv1PHHyhnkY9lrL7etaEgOFcME
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@@ -168,6 +179,7 @@ github.com/modern-go/concurrent v0.0.0-20180306012644-bacd9c7ef1dd/go.mod h1:6dJ
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@@ -186,6 +198,7 @@ github.com/pelletier/go-toml v1.4.0/go.mod h1:PN7xzY2wHTK0K9p34ErDQMlFxa51Fk0OUr
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@@ -213,6 +226,7 @@ github.com/russross/blackfriday v1.5.2 h1:HyvC0ARfnZBqnXwABFeSZHpKvJHJJfPz81GNue
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@@ -228,10 +242,12 @@ github.com/sirupsen/logrus v1.2.0/go.mod h1:LxeOpSwHxABJmUn/MG1IvRgCAasNZTLOkJPx
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@@ -239,6 +255,7 @@ github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+
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@@ -252,6 +269,7 @@ github.com/unknwon/paginater v0.0.0-20170405233947-45e5d631308e h1:Qf3QQl/zmEbWD
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 github.com/urfave/cli v1.22.1 h1:+mkCCcOFKPnCmVYVcURKps1Xe+3zP90gSYGNfRkjoIY=
 github.com/urfave/cli v1.22.1/go.mod h1:Gos4lmkARVdJ6EkW0WaNv/tZAAMe9V7XWyB60NtXRu0=
+github.com/ziutek/mymysql v1.5.4 h1:GB0qdRGsTwQSBVYuVShFBKaXSnSnYYC2d9knnE1LHFs=
 github.com/ziutek/mymysql v1.5.4/go.mod h1:LMSpPZ6DbqWFxNCHW77HeMg9I646SAhApZ/wKdgO/C0=
 go.opencensus.io v0.20.1/go.mod h1:6WKK9ahsWS3RSO+PY9ZHZUfv2irvY6gN279GOPZjmmk=
 golang.org/x/crypto v0.0.0-20180904163835-0709b304e793/go.mod h1:6SG95UA2DQfeDnfUPMdvaQW0Q7yPrPDi9nlGo2tz2b4=
@@ -320,6 +338,7 @@ google.golang.org/api v0.3.1/go.mod h1:6wY9I6uQWHQ8EM57III9mq/AjF+i8G65rmVagqKMt
 google.golang.org/appengine v1.1.0/go.mod h1:EbEs0AVv82hx2wNQdGPgUI5lhzA/G0D9YwlJXL52JkM=
 google.golang.org/appengine v1.4.0/go.mod h1:xpcJRLb0r/rnEns0DIKYYv+WjYCduHsrkT7/EB5XEv4=
 google.golang.org/appengine v1.6.0/go.mod h1:xpcJRLb0r/rnEns0DIKYYv+WjYCduHsrkT7/EB5XEv4=
+google.golang.org/appengine v1.6.1 h1:QzqyMA1tlu6CgqCDUtU9V+ZKhLFT2dkJuANu5QaxI3I=
 google.golang.org/appengine v1.6.1/go.mod h1:i06prIuMbXzDqacNJfV5OdTW448YApPu5ww/cMBSeb0=
 google.golang.org/genproto v0.0.0-20180817151627-c66870c02cf8/go.mod h1:JiN7NxoALGmiZfu7CAH4rXhgtRTLTxftemlI0sWmxmc=
 google.golang.org/genproto v0.0.0-20190307195333-5fe7a883aa19/go.mod h1:VzzqZJRnGkLBvHegQrXjBqPurQTc5/KpmUdxsrq26oE=
@@ -327,12 +346,14 @@ google.golang.org/genproto v0.0.0-20190404172233-64821d5d2107/go.mod h1:VzzqZJRn
 google.golang.org/grpc v1.17.0/go.mod h1:6QZJwpn2B+Zp71q/5VxRsJ6NXXVCE5NRUHRo+f3cWCs=
 google.golang.org/grpc v1.19.0/go.mod h1:mqu4LbDTu4XGKhr4mRzUsmM4RtVoemTSY81AxZiDr8c=
 gopkg.in/alecthomas/kingpin.v2 v2.2.6/go.mod h1:FMv+mEhP44yOT+4EoQTLFTRgOQ1FBLkstjWtayDeSgw=
+gopkg.in/alexcesaro/quotedprintable.v3 v3.0.0-20150716171945-2caba252f4dc h1:2gGKlE2+asNV9m7xrywl36YYNnBG5ZQ0r/BOOxqPpmk=
 gopkg.in/alexcesaro/quotedprintable.v3 v3.0.0-20150716171945-2caba252f4dc/go.mod h1:m7x9LTH6d71AHyAX77c9yqWCCa3UKHcVEj9y7hAtKDk=
 gopkg.in/asn1-ber.v1 v1.0.0-20181015200546-f715ec2f112d h1:TxyelI5cVkbREznMhfzycHdkp5cLA7DpE+GKjSslYhM=
 gopkg.in/asn1-ber.v1 v1.0.0-20181015200546-f715ec2f112d/go.mod h1:cuepJuh7vyXfUyUwEgHQXw849cJrilpS5NeIjOWESAw=
 gopkg.in/bufio.v1 v1.0.0-20140618132640-567b2bfa514e h1:wGA78yza6bu/mWcc4QfBuIEHEtc06xdiU0X8sY36yUU=
 gopkg.in/bufio.v1 v1.0.0-20140618132640-567b2bfa514e/go.mod h1:xsQCaysVCudhrYTfzYWe577fCe7Ceci+6qjO2Rdc0Z4=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/check.v1 v1.0.0-20180628173108-788fd7840127 h1:qIbj1fsPNlZgppZ+VLlY7N33q108Sa+fhmuc+sWQYwY=
 gopkg.in/check.v1 v1.0.0-20180628173108-788fd7840127/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/clog.v1 v1.2.0 h1:BHfwHRNQy497iBNsRBassPixSAxRbn2z5KVkdBFbwxc=
 gopkg.in/clog.v1 v1.2.0/go.mod h1:L6fgdpdhFgKX4eGuDvt+N6X2GwZE160NRrIHzvaF8ZM=

internal/markup/markdown.go

@@ -157,8 +157,7 @@ func RawMarkdown(body []byte, urlPrefix string) []byte {
 		extensions |= blackfriday.EXTENSION_HARD_LINE_BREAK
 	}
 
-	body = blackfriday.Markdown(body, renderer, extensions)
-	return body
+	return blackfriday.Markdown(body, renderer, extensions)
 }
 
 // Markdown takes a string or []byte and renders to HTML in Markdown syntax with special links.

internal/markup/markup.go

@@ -367,7 +367,7 @@ func Detect(filename string) Type {
 	}
 }
 
-// Render takes a string or []byte and renders to HTML in given type of syntax with special links.
+// Render takes a string or []byte and renders to sanitized HTML in given type of syntax with special links.
 func Render(typ Type, input interface{}, urlPrefix string, metas map[string]string) []byte {
 	var rawBytes []byte
 	switch v := input.(type) {

internal/route/api/v1/misc/markdown.go

@@ -20,16 +20,18 @@ func Markdown(c *context.APIContext, form api.MarkdownOption) {
 	}
 
 	if len(form.Text) == 0 {
-		c.Write([]byte(""))
+		_, _ = c.Write([]byte(""))
 		return
 	}
 
+	var md []byte
 	switch form.Mode {
 	case "gfm":
-		c.Write(markup.Markdown([]byte(form.Text), form.Context, nil))
+		md = markup.Markdown([]byte(form.Text), form.Context, nil)
 	default:
-		c.Write(markup.RawMarkdown([]byte(form.Text), ""))
+		md = markup.SanitizeBytes(markup.RawMarkdown([]byte(form.Text), ""))
 	}
+	_, _ = c.Write(md)
 }
 
 func MarkdownRaw(c *context.APIContext) {
@@ -38,5 +40,5 @@ func MarkdownRaw(c *context.APIContext) {
 		c.Error(http.StatusUnprocessableEntity, "", err)
 		return
 	}
-	c.Write(markup.RawMarkdown(body, ""))
+	_, _ = c.Write(markup.SanitizeBytes(markup.RawMarkdown(body, "")))
 }