log: better sanitation (#26556)

log/format.go

@@ -86,6 +86,7 @@ type TerminalStringer interface {
 //	[DBUG] [May 16 20:58:45] remove route ns=haproxy addr=127.0.0.1:50002
 func TerminalFormat(usecolor bool) Format {
 	return FormatFunc(func(r *Record) []byte {
+		msg := escapeMessage(r.Msg)
 		var color = 0
 		if usecolor {
 			switch r.Lvl {
@@ -122,19 +123,19 @@ func TerminalFormat(usecolor bool) Format {
 
 			// Assemble and print the log heading
 			if color > 0 {
-				fmt.Fprintf(b, "\x1b[%dm%s\x1b[0m[%s|%s]%s %s ", color, lvl, r.Time.Format(termTimeFormat), location, padding, r.Msg)
+				fmt.Fprintf(b, "\x1b[%dm%s\x1b[0m[%s|%s]%s %s ", color, lvl, r.Time.Format(termTimeFormat), location, padding, msg)
 			} else {
-				fmt.Fprintf(b, "%s[%s|%s]%s %s ", lvl, r.Time.Format(termTimeFormat), location, padding, r.Msg)
+				fmt.Fprintf(b, "%s[%s|%s]%s %s ", lvl, r.Time.Format(termTimeFormat), location, padding, msg)
 			}
 		} else {
 			if color > 0 {
-				fmt.Fprintf(b, "\x1b[%dm%s\x1b[0m[%s] %s ", color, lvl, r.Time.Format(termTimeFormat), r.Msg)
+				fmt.Fprintf(b, "\x1b[%dm%s\x1b[0m[%s] %s ", color, lvl, r.Time.Format(termTimeFormat), msg)
 			} else {
-				fmt.Fprintf(b, "%s[%s] %s ", lvl, r.Time.Format(termTimeFormat), r.Msg)
+				fmt.Fprintf(b, "%s[%s] %s ", lvl, r.Time.Format(termTimeFormat), msg)
 			}
 		}
 		// try to justify the log output for short messages
-		length := utf8.RuneCountInString(r.Msg)
+		length := utf8.RuneCountInString(msg)
 		if len(r.Ctx) > 0 && length < termMsgJust {
 			b.Write(bytes.Repeat([]byte{' '}, termMsgJust-length))
 		}
@@ -167,6 +168,8 @@ func logfmt(buf *bytes.Buffer, ctx []interface{}, color int, term bool) {
 		v := formatLogfmtValue(ctx[i+1], term)
 		if !ok {
 			k, v = errorKey, formatLogfmtValue(k, term)
+		} else {
+			k = escapeString(k)
 		}
 
 		// XXX: we should probably check that all of your key bytes aren't invalid
@@ -471,7 +474,7 @@ func formatLogfmtBigInt(n *big.Int) string {
 func escapeString(s string) string {
 	needsQuoting := false
 	for _, r := range s {
-		// We quote everything below " (0x34) and above~ (0x7E), plus equal-sign
+		// We quote everything below " (0x22) and above~ (0x7E), plus equal-sign
 		if r <= '"' || r > '~' || r == '=' {
 			needsQuoting = true
 			break
@@ -482,3 +485,26 @@ func escapeString(s string) string {
 	}
 	return strconv.Quote(s)
 }
+
+// escapeMessage checks if the provided string needs escaping/quoting, similarly
+// to escapeString. The difference is that this method is more lenient: it allows
+// for spaces and linebreaks to occur without needing quoting.
+func escapeMessage(s string) string {
+	needsQuoting := false
+	for _, r := range s {
+		// Carriage return and Line feed are ok
+		if r == 0xa || r == 0xd {
+			continue
+		}
+		// We quote everything below <space> (0x20) and above~ (0x7E),
+		// plus equal-sign
+		if r < ' ' || r > '~' || r == '=' {
+			needsQuoting = true
+			break
+		}
+	}
+	if !needsQuoting {
+		return s
+	}
+	return strconv.Quote(s)
+}

log/format_test.go

 package log
 
 import (
+	"fmt"
 	"math"
 	"math/big"
 	"math/rand"
+	"strings"
 	"testing"
 )
 
@@ -93,3 +95,47 @@ func BenchmarkPrettyUint64Logfmt(b *testing.B) {
 		sink = FormatLogfmtUint64(rand.Uint64())
 	}
 }
+
+func TestSanitation(t *testing.T) {
+	msg := "\u001b[1G\u001b[K\u001b[1A"
+	msg2 := "\u001b  \u0000"
+	msg3 := "NiceMessage"
+	msg4 := "Space Message"
+	msg5 := "Enter\nMessage"
+
+	for i, tt := range []struct {
+		msg  string
+		want string
+	}{
+		{
+			msg:  msg,
+			want: fmt.Sprintf("] %q                   %q=%q\n", msg, msg, msg),
+		},
+		{
+			msg:  msg2,
+			want: fmt.Sprintf("] %q                             %q=%q\n", msg2, msg2, msg2),
+		},
+		{
+			msg:  msg3,
+			want: fmt.Sprintf("] %s                              %s=%s\n", msg3, msg3, msg3),
+		},
+		{
+			msg:  msg4,
+			want: fmt.Sprintf("] %s                            %q=%q\n", msg4, msg4, msg4),
+		},
+		{
+			msg:  msg5,
+			want: fmt.Sprintf("] %s                            %q=%q\n", msg5, msg5, msg5),
+		},
+	} {
+		var (
+			logger = New()
+			out    = new(strings.Builder)
+		)
+		logger.SetHandler(LvlFilterHandler(LvlInfo, StreamHandler(out, TerminalFormat(false))))
+		logger.Info(tt.msg, tt.msg, tt.msg)
+		if have := out.String()[24:]; tt.want != have {
+			t.Fatalf("test %d: want / have: \n%v\n%v", i, tt.want, have)
+		}
+	}
+}