ui-shared: prevent malicious filename from injecting headers

html.c

@@ -239,6 +239,32 @@ void html_url_arg(const char *txt)
 		html(txt);
 }
 
+void html_header_arg_in_quotes(const char *txt)
+{
+	const char *t = txt;
+	while (t && *t) {
+		unsigned char c = *t;
+		const char *e = NULL;
+		if (c == '\\')
+			e = "\\\\";
+		else if (c == '\r')
+			e = "\\r";
+		else if (c == '\n')
+			e = "\\n";
+		else if (c == '"')
+			e = "\\\"";
+		if (e) {
+			html_raw(txt, t - txt);
+			html(e);
+			txt = t + 1;
+		}
+		t++;
+	}
+	if (t != txt)
+		html(txt);
+
+}
+
 void html_hidden(const char *name, const char *value)
 {
 	html("<input type='hidden' name='");

html.h

@@ -23,6 +23,7 @@ extern void html_ntxt(int len, const char *txt);
 extern void html_attr(const char *txt);
 extern void html_url_path(const char *txt);
 extern void html_url_arg(const char *txt);
+extern void html_header_arg_in_quotes(const char *txt);
 extern void html_hidden(const char *name, const char *value);
 extern void html_option(const char *value, const char *text, const char *selected_value);
 extern void html_intoption(int value, const char *text, int selected_value);

ui-shared.c

@@ -692,9 +692,11 @@ void cgit_print_http_headers(void)
 		htmlf("Content-Type: %s\n", ctx.page.mimetype);
 	if (ctx.page.size)
 		htmlf("Content-Length: %zd\n", ctx.page.size);
-	if (ctx.page.filename)
-		htmlf("Content-Disposition: inline; filename=\"%s\"\n",
-		      ctx.page.filename);
+	if (ctx.page.filename) {
+		html("Content-Disposition: inline; filename=\"");
+		html_header_arg_in_quotes(ctx.page.filename);
+		html("\"\n");
+	}
 	if (!ctx.env.authenticated)
 		html("Cache-Control: no-cache, no-store\n");
 	htmlf("Last-Modified: %s\n", http_date(ctx.page.modified));