From: Greg Kurz <groug@kaod.org>
Date: Thu, 25 May 2017 08:30:13 +0000 (+0200)
Subject: fsdev: fix virtfs-proxy-helper cwd
X-Git-Tag: v2.10.0-rc0~165^2~6
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=4be56c19593c15bc8d16abcb63bfdd4697a5754d;p=thirdparty%2Fqemu.git

fsdev: fix virtfs-proxy-helper cwd

Since chroot() doesn't change the current directory, it is indeed a good
practice to chdir() to the target directory and then then chroot(), or
to chroot() to the target directory and then chdir("/").

The current code does neither of them actually. Let's go for the latter.

This doesn't fix any security issue since all of this takes place before
the helper begins to process requests.

Signed-off-by: Greg Kurz <groug@kaod.org>
Reviewed-by: Eric Blake <eblake@redhat.com>
---

diff --git a/fsdev/virtfs-proxy-helper.c b/fsdev/virtfs-proxy-helper.c
index 54f7ad1c48f..4c4238f62e5 100644
--- a/fsdev/virtfs-proxy-helper.c
+++ b/fsdev/virtfs-proxy-helper.c
@@ -1129,14 +1129,14 @@ int main(int argc, char **argv)
         }
     }
 
-    if (chdir("/") < 0) {
-        do_perror("chdir");
-        goto error;
-    }
     if (chroot(rpath) < 0) {
         do_perror("chroot");
         goto error;
     }
+    if (chdir("/") < 0) {
+        do_perror("chdir");
+        goto error;
+    }
 
     get_version = false;
 #ifdef FS_IOC_GETVERSION