Re: [libvirt] [PATCH 3/4] security: Introduce method for labeling file descriptors of created files

On 06/27/13 20:51, Daniel P. Berrange wrote: >On Wed, Jun 26, 2013 at 03:01:49PM +0200, Peter Krempa wrote: >>The method labels the file descriptor even if dynamic labeling/relabeling >>is turned off. This is needed for files created by libvirt and then >>passed along to qemu as a FD. >>--- >> src/libvirt_private.syms | 1 + >> src/security/security_dac.c | 9 +++++++++ >> src/security/security_driver.h | 4 ++++ >> src/security/security_manager.c | 16 ++++++++++++++++ >> src/security/security_manager.h | 3 +++ >> src/security/security_nop.c | 1 + >> src/security/security_selinux.c | 21 +++++++++++++++++++++ >> src/security/security_stack.c | 19 +++++++++++++++++++ >> 8 files changed, 74 insertions(+) >> > >>diff --git a/src/security/security_selinux.c b/src/security/security_selinux.c >>index 7802dda..5894259 100644 >>--- a/src/security/security_selinux.c >>+++ b/src/security/security_selinux.c >>@@ -2446,6 +2446,26 @@ virSecuritySELinuxGetSecurityMountOptions(virSecurityManagerPtr mgr, >> return opts; >> } >> >>+static int >>+virSecuritySELinuxSetCreatedFDLabel(virSecurityManagerPtr mgr ATTRIBUTE_UNUSED, >>+ virDomainDefPtr def, >>+ int fd) >>+{ >>+ virSecurityLabelDefPtr secdef; >>+ >>+ if ((secdef = virDomainDefGetSecurityLabelDef(def, SECURITY_SELINUX_NAME))) { >>+ if (!secdef->imagelabel) >>+ secdef->imagelabel = virSecuritySELinuxGenImageLabel(mgr, def); > >This is really dubious. None of the methods except for GenSecurityLabel >should be making changes to the secdef state. There is already an exception: virSecuritySELinuxGetSecurityMountOptions().

> >>+ >>+ if (secdef->imagelabel == NULL) >>+ return 0; >>+ >>+ return virSecuritySELinuxFSetFilecon(fd, secdef->imagelabel); >>+} > > >In general I'm not really convinced we should be adding a new method >here, as opposed to making the existing SetImageFDLabel do the right >thing. I was going to suggest expanding the function prototype with a bool that would allow to choose whether to label the image always or only if relabeling is enabled but looking through the code I noticed that actually every caller would need to have this flag enabled. There are currently 4 places this method is called: qemuDumpToFd() - labels a FD of a freshly created file for the memory dump qemuMigrationToFile() - again a new file FD is labeled, used for (managed) save and dumping of memory doTunnelMigrate() - the FD's of a pipe used for extracting data into the stream are labeled, again this would probably fail with static labeling. qemuProcessStart() - the migration FD is labelled on process start. I think it's safe (and necessary) to relabel these even if relabeling is disabled and thus we can change the function to always label FD's. Do you agree?