Re: [PATCH v2 1/3] qemu_passt: Don't make passt transition to svirt_t/libvirt_domain on start

qemuSecurityCommandRun() causes an explicit domain transition of the new process, but passt ships with its own SELinux policy, with external interfaces for libvirtd, so we simply need to transition from virtd_t to passt_t as passt is executed. The qemu type enforcement rules have little to do with it. That is, if we switch to svirt_t, passt will run in the security context that's intended for QEMU, which allows a number of operations not needed by passt. On the other hand, with a switch to svirt_t, passt won't be able to create its own PID file. Usage of those new interfaces is implemented by this change in selinux-policy: https://github.com/fedora-selinux/selinux-policy/pull/1613 Replace qemuSecurityCommandRun() with virCommandRun(), and explicitly set the label, preserving the correct MCS range for the given VM instance. This is a temporary measure: eventually, we'll need a more generic and elegant mechanism for helper binaries. Fixes: a56f0168d576 ("qemu: hook up passt config to qemu domains") Signed-off-by: Stefano Brivio <sbrivio(a)redhat.com&gt; --- src/qemu/qemu_passt.c | 33 +++++++++++++++++++++++++++------ 1 file changed, 27 insertions(+), 6 deletions(-) diff --git a/src/qemu/qemu_passt.c b/src/qemu/qemu_passt.c index 1217a6a087..81f48dd630 100644 --- a/src/qemu/qemu_passt.c +++ b/src/qemu/qemu_passt.c @@ -30,6 +30,11 @@ #include "virlog.h" #include "virpidfile.h" +#ifdef WITH_SELINUX +# include <selinux/selinux.h> +# include <selinux/context.h> +#endif + #define VIR_FROM_THIS VIR_FROM_NONE VIR_LOG_INIT("qemu.passt"); @@ -158,8 +163,11 @@ qemuPasstStart(virDomainObj *vm, g_autofree char *errbuf = NULL; char macaddr[VIR_MAC_STRING_BUFLEN]; size_t i; - int exitstatus = 0; - int cmdret = 0; +#ifdef WITH_SELINUX + virSecurityLabelDef *seclabel; + context_t s; + const char *newLabel; +#endif cmd = virCommandNew(PASST); @@ -271,18 +279,31 @@ qemuPasstStart(virDomainObj *vm, if (qemuExtDeviceLogCommand(driver, vm, cmd, "passt") < 0) return -1; - if (qemuSecurityCommandRun(driver, vm, cmd, -1, -1, &exitstatus, &cmdret) < 0) - goto error; +#ifdef WITH_SELINUX + /* TODO: Implement a new security manager function for helper binaries, + * possibly deriving domain names from security attributes of the helper + * binary itself. + */ + seclabel = virDomainDefGetSecurityLabelDef(vm->def, "selinux"); + s = context_new(seclabel->label); + context_type_set(s, "passt_t"); + newLabel = context_str(s); + + virCommandSetSELinuxLabel(cmd, newLabel); +#endif - if (cmdret < 0 || exitstatus != 0) { + if (virCommandRun(cmd, NULL)) { virReportError(VIR_ERR_INTERNAL_ERROR, _("Could not start 'passt': %s"), NULLSTR(errbuf)); goto error; } + context_free(s);

+ return 0; error: - qemuPasstKill(pidfile); + context_free(s);

+ qemuPasstKill(pidfile, passtSocketName); return -1; }