Re: [libvirt] [PATCH 2/2] libvirt patch to write a mcs translation file to /run/setrans directory

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On 05/17/2013 05:52 AM, Daniel P. Berrange wrote: > On Wed, May 15, 2013 at 02:36:32PM -0400, dwalsh(a)redhat.com wrote: >> From: Dan Walsh <dwalsh(a)redhat.com&gt; >> >> mcstransd is a translation tool that can translate MCS Labels into human >> understandable code. I have patched it to watch for translation files in >> the /run/setrans directory. This allows us to run commands like ps -eZ >> and see system_u:system_r:svirt_t:Fedora18 rather then >> system_u:system_r:svirt_t:s0:c1,c2. When used with containers it would >> make an easy way to list all processes within a container using ps -eZ | >> grep Fedora18 --- src/security/security_selinux.c | 59 >> ++++++++++++++++++++++++++++++++++++++++- 1 file changed, 58 >> insertions(+), 1 deletion(-) >> >> diff --git a/src/security/security_selinux.c >> b/src/security/security_selinux.c index 5d108b9..cbcd013 100644 --- >> a/src/security/security_selinux.c +++ b/src/security/security_selinux.c >> @@ -83,6 +83,57 @@ >> virSecuritySELinuxRestoreSecurityTPMFileLabelInt(virSecurityManagerPtr >> mgr, virDomainTPMDefPtr tpm); >> >> >> +static int +virSecuritySELinuxAddMCSFile(const char *name, + >> const char *label) +{ + int ret = -1; + char *tmp = NULL; + >> context_t con = NULL; + + if (virAsprintf(&tmp, "%s/%s", >> SELINUX_TRANS_DIR, name) < 0) { + virReportOOMError(); + >> return -1; + } + if (! (con = context_new(label))) { + >> virReportSystemError(errno, "%s", + _("unable >> to allocate security context")); + goto cleanup; + } + if >> (virFileWriteStr(tmp, context_range_get(con), 0) < 0) { + >> virReportSystemError(errno, + _("unable to >> create MCS file %s"), tmp); + goto cleanup; + } + ret = 0; >> + +cleanup: + VIR_FREE(tmp); + context_free(con); + return ret; >> +} + +static int +virSecuritySELinuxRemoveMCSFile(const char *name) +{ + >> char *tmp=NULL; + int ret = -1; + if (virAsprintf(&tmp, "%s/%s", >> SELINUX_TRANS_DIR, name) < 0) { + virReportOOMError(); + >> return -1; + } + if (unlink(tmp) < 0 && errno != ENOENT) { + >> virReportSystemError(errno, + _("Unable to >> remove MCS file %s"), tmp); + goto cleanup; + } + ret = 0; >> + +cleanup: + VIR_FREE(tmp); + return ret; +} + /* * Returns 0 on >> success, 1 if already reserved, or -1 on fatal error */ @@ -1953,7 >> +2004,7 @@ virSecuritySELinuxReleaseSecurityLabel(virSecurityManagerPtr >> mgr, } VIR_FREE(secdef->imagelabel); >> >> - return 0; + return virSecuritySELinuxRemoveMCSFile(def->name); } >> >> >> @@ -2047,10 +2098,16 @@ >> virSecuritySELinuxSetSecurityProcessLabel(virSecurityManagerPtr mgr >> ATTRIBUTE_UN return -1; } >> >> + if (virSecuritySELinuxAddMCSFile(def->name, secdef->label) < 0) { + >> if (security_getenforce() == 1) + return -1; + } + > > As you mentioned offlist, this is not going to work because the > SetProcessLabel function is called in a child process, where you can't > guarantee to see the host's /run directory. > > Instead it should be done in the GenSecurityLabel function which is called > from a safe context. > > > Daniel > Fine, but what about the case where the user is running libvirt and libvirt is not allowed to write to /run/setrans. Should we just silently fail in this case?