common/config: don't hard-code SELinux context

If SELinux is enabled, by default xfstests mounts its filesystems
with "-o context=system_u:object_r:nfs_t:s0" so that no SELinux
xattrs get created and interfere with tests.  However, this
particular context is not guaranteed to be available because the
context names are a detail of the SELinux policy.  The SELinux
policy on Android systems, for example, does not have a context with
this name.

To fix this without having to manually override
SELINUX_MOUNT_OPTIONS, just grab the SELinux context of the root
directory.  This is arbitrary, but it should always provide a valid
context.  And if for some reason someone is actually running
xfstests in a specific SELinux context that needs files labeled with
a particular context, then they may still override
SELINUX_MOUNT_OPTIONS.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Eryu Guan <eguan@redhat.com>
Signed-off-by: Eryu Guan <eguan@redhat.com>

diff --git a/common/config b/common/config
index 0c7335ad44986e70d955911e1472951e69ddfa52..57c7dc3f676ac22be4dabb8d13e81d1cc4d2ade6 100644 (file)
--- a/common/config
+++ b/common/config
@@ -260,10 +260,16 @@ case "$HOSTOS" in
 esac
 
 # SELinux adds extra xattrs which can mess up our expected output.
-# So, mount with a context, and they won't be created
-# # nfs_t is a "liberal" context so we can use it.
+# So, mount with a context, and they won't be created.
+#
+# Since the context= option only accepts contexts defined in the SELinux
+# policy, and different systems may have different policies with
+# different context names, use the context of an existing directory.
+# Assume that any valid context is fine, since xfstests should really
+# only be run from an "unconfined" process, or with SELinux in permissive
+# mode.  But if not, just specify your own SELINUX_MOUNT_OPTIONS.
 if [ -x /usr/sbin/selinuxenabled ] && /usr/sbin/selinuxenabled; then
-       : ${SELINUX_MOUNT_OPTIONS:="-o context=system_u:object_r:nfs_t:s0"}
+       : ${SELINUX_MOUNT_OPTIONS:="-o context=$(stat -c %C /)"}
        export SELINUX_MOUNT_OPTIONS
 fi