Re: [libvirt] [PATCH 1/2] selinux: load and free selinux active file contexts configuration database

On 10/15/2012 06:40 PM, Martin Kletzander wrote: >On 10/15/2012 12:22 PM, Daniel P. Berrange wrote: >>On Mon, Oct 15, 2012 at 03:12:45PM +0800, Guannan Ren wrote: >>>If we use matchpathcon() to look up selinux context for specific pathname, >>>it'd better actively load file contexts database by matchpathcon_init() >>>and free memory when finished using matchpathcon by matchpathcon_fini(). >>>--- >>> src/security/security_selinux.c | 8 ++++++++ >>> 1 file changed, 8 insertions(+) >>> >>>diff --git a/src/security/security_selinux.c b/src/security/security_selinux.c >>>index 10135ed..b278e2c 100644 >>>--- a/src/security/security_selinux.c >>>+++ b/src/security/security_selinux.c >>>@@ -667,6 +667,10 @@ virSecuritySELinuxSecurityDriverProbe(const char *virtDriver) >>> static int >>> virSecuritySELinuxSecurityDriverOpen(virSecurityManagerPtr mgr) >>> { >>>+#ifndef HAVE_SELINUX_LABEL_H >>>+ if (matchpathcon_init(NULL) < 0) >>>+ VIR_WARN("cannot load selinux active file contexts configuration"); >>>+#endif >>> return virSecuritySELinuxInitialize(mgr); >>> } >>>@@ -685,6 +689,10 @@ virSecuritySELinuxSecurityDriverClose(virSecurityManagerPtr mgr) >>> VIR_FREE(data->file_context); >>> VIR_FREE(data->content_context); >>>+#ifndef HAVE_SELINUX_LABEL_H >>>+ if (matchpathcon_fini() < 0) >>>+ VIR_WARN("cannot free allocated memory for selinux"); >>>+#endif >>> return 0; >>> } >>I'm not convinced this is safe, because the security drivers can be >>opened multiple times, eg LXC and QEMU, and this is changing the global >>static state of the SELinux library. >> >I didn't think the driver is opened for every other driver used. In >this case the initialization of the matchpathcon should be dealt with in >some other way. Or can't we open the security driver only once? > >@Guannan: is there a problem this fixes? How come it worked without the >init before? > >Martin > No, there is no a bug/problem to fix, the patch just actively initializes the active context configuration database. If we don't do this, the matchpathcon will do it instead. I am going to add them in a better way later.