From 41241ca044a55ce1c5006cc4581f643fd3e5b20d Mon Sep 17 00:00:00 2001
From: reyk <reyk@openbsd.org>
Date: Wed, 13 Aug 2014 16:04:28 +0000
Subject: [PATCH] Provide a failsafe version of the path_info() function that
 doesn't need a temporary path variable.  Based on an initial diff from
 chrisz@.

"Commit any failsafe version and I'm ok with it" chrisz@
---
 usr.sbin/httpd/httpd.c       | 31 ++++++++++++++++++-------------
 usr.sbin/httpd/httpd.h       |  4 ++--
 usr.sbin/httpd/server_fcgi.c | 11 +++++------
 3 files changed, 25 insertions(+), 21 deletions(-)

diff --git a/usr.sbin/httpd/httpd.c b/usr.sbin/httpd/httpd.c
index d5ca6e4067c..4b631ec7353 100644
--- a/usr.sbin/httpd/httpd.c
+++ b/usr.sbin/httpd/httpd.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: httpd.c,v 1.18 2014/08/13 08:08:55 chrisz Exp $	*/
+/*	$OpenBSD: httpd.c,v 1.19 2014/08/13 16:04:28 reyk Exp $	*/
 
 /*
  * Copyright (c) 2014 Reyk Floeter <reyk@openbsd.org>
@@ -580,28 +580,33 @@ canonicalize_path(const char *input, char *path, size_t len)
 	return (path);
 }
 
-ssize_t
-path_info(char *name)
+size_t
+path_info(char *path)
 {
-	char		*p, *start, *end;
-	char		 path[MAXPATHLEN];
+	char		*p, *start, *end, ch;
 	struct stat	 st;
-
-	if (strlcpy(path, name, sizeof(path)) >= sizeof(path))
-		return (-1);
+	int		 ret;
 
 	start = path;
 	end = start + strlen(path);
 
-	for (p = end; p >= start; p--) {
-		if (*p != '/')
+	for (p = end; p > start; p--) {
+		/* Scan every path component from the end and at each '/' */
+		if (p < end && *p != '/')
 			continue;
-		if (stat(path, &st) == 0)
-			break;
+
+		/* Temporarily cut the path component out */
+		ch = *p;
 		*p = '\0';
+		ret = stat(path, &st);
+		*p = ch;
+
+		/* Break if the initial path component was found */
+		if (ret == 0)
+			break;
 	}
 
-	return (strlen(path));
+	return (p - start);
 }
 
 void
diff --git a/usr.sbin/httpd/httpd.h b/usr.sbin/httpd/httpd.h
index 1a8042840c0..371dd1caac0 100644
--- a/usr.sbin/httpd/httpd.h
+++ b/usr.sbin/httpd/httpd.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: httpd.h,v 1.52 2014/08/08 18:29:42 reyk Exp $	*/
+/*	$OpenBSD: httpd.h,v 1.53 2014/08/13 16:04:28 reyk Exp $	*/
 
 /*
  * Copyright (c) 2006 - 2014 Reyk Floeter <reyk@openbsd.org>
@@ -537,7 +537,7 @@ void		 event_again(struct event *, int, short,
 		    struct timeval *, struct timeval *, void *);
 const char	*canonicalize_host(const char *, char *, size_t);
 const char	*canonicalize_path(const char *, char *, size_t);
-ssize_t		 path_info(char *);
+size_t		 path_info(char *);
 void		 imsg_event_add(struct imsgev *);
 int		 imsg_compose_event(struct imsgev *, u_int16_t, u_int32_t,
 		    pid_t, int, void *, u_int16_t);
diff --git a/usr.sbin/httpd/server_fcgi.c b/usr.sbin/httpd/server_fcgi.c
index e740883c144..d191ef21aee 100644
--- a/usr.sbin/httpd/server_fcgi.c
+++ b/usr.sbin/httpd/server_fcgi.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: server_fcgi.c,v 1.31 2014/08/11 15:26:33 deraadt Exp $	*/
+/*	$OpenBSD: server_fcgi.c,v 1.32 2014/08/13 16:04:28 reyk Exp $	*/
 
 /*
  * Copyright (c) 2014 Florian Obser <florian@openbsd.org>
@@ -100,7 +100,7 @@ server_fcgi(struct httpd *env, struct client *clt)
 	struct fcgi_record_header	*h;
 	struct fcgi_begin_request_body	*begin;
 	char				 hbuf[MAXHOSTNAMELEN];
-	ssize_t				 scriptlen;
+	ssize_t				 scriptlen, pathlen;
 	int				 fd = -1, ret;
 	const char			*errstr = NULL;
 	char				*str, *p, *script = NULL;
@@ -191,15 +191,14 @@ server_fcgi(struct httpd *env, struct client *clt)
 	h->type = FCGI_PARAMS;
 	h->content_len = param.total_len = 0;
 
-	if (asprintf(&script, "%s%s", srv_conf->root,
+	if ((pathlen = (ssize_t)asprintf(&script, "%s%s", srv_conf->root,
 	    desc->http_path_alias != NULL ?
-	    desc->http_path_alias : desc->http_path) == -1 ||
-	    (scriptlen = path_info(script)) == -1) {
+	    desc->http_path_alias : desc->http_path)) == -1) {
 		errstr = "failed to get script name";
 		goto fail;
 	}
 
-	if (scriptlen) {
+	if ((scriptlen = path_info(script)) < pathlen) {
 		if (fcgi_add_param(&param, "PATH_INFO",
 		    script + scriptlen, clt) == -1) {
 			errstr = "failed to encode param";
-- 
2.20.1