On 5/7/21 6:24 PM, Daniel P. Berrangé wrote:
When creating the system identity set the system token. The system token is currently stored in a local path
/var/run/libvirt/common/system.token
Obviously with only traditional UNIX DAC in effect, this is largely security through obscurity, if the client is running at the same privilege level as the daemon. It does, however, reliably distinguish an unprivilegd client from the system daemons.
With a MAC system like SELinux though, or possible use of containers, access can be further restricted.
A possible future improvement for Linux would be to populate the kernel keyring with a secret for libvirt daemons to share.
Reviewed-by: Michal Privoznik <mprivozn@redhat.com> Signed-off-by: Daniel P. Berrangé <berrange@redhat.com> --- src/util/viridentity.c | 102 +++++++++++++++++++++++++++++++++++++++++ 1 file changed, 102 insertions(+)
diff --git a/src/util/viridentity.c b/src/util/viridentity.c index 7da4ea12f5..8c939a507e 100644 --- a/src/util/viridentity.c +++ b/src/util/viridentity.c
@@ -144,6 +154,98 @@ int virIdentitySetCurrent(virIdentity *ident) }
+#define TOKEN_BYTES 16 +#define TOKEN_STRLEN (TOKEN_BYTES * 2) + +static char * +virIdentityConstructSystemTokenPath(void) +{ + g_autofree char *commondir = NULL; + if (geteuid() == 0) { + commondir = g_strdup(RUNSTATEDIR "/libvirt/common"); + } else { + g_autofree char *rundir = virGetUserRuntimeDirectory(); + commondir = g_strdup_printf("%s/common", rundir); + } + + if (g_mkdir_with_parents(commondir, 0700) < 0) { + virReportSystemError(errno, + _("Cannot create daemon common directory '%s'"), + commondir); + return NULL; + } + + return g_strdup_printf("%s/system.token", commondir); +} + + +static char * +virIdentityEnsureSystemToken(void) +{ + g_autofree char *tokenfile = virIdentityConstructSystemTokenPath(); + g_autofree char *token = NULL; + VIR_AUTOCLOSE fd = -1; + struct stat st; +
Sorry for not spotting this in v1, but @tokenfile can be NULL here, in which case virIdentityConstructSystemTokenPath() already reported accurate error. Something like: if (!tokenfile) return NULL; is sufficient.
+ fd = open(tokenfile, O_RDWR|O_APPEND|O_CREAT, 0600); + if (fd < 0) { + virReportSystemError(errno, + _("Unable to open system token %s"), + tokenfile); + return NULL; + } +
Also, I believe you will want to mock this function, because if you don't then the viridentitytest starts failing after next patch. Something among these lines: https://gitlab.com/MichalPrivoznik/libvirt/-/commit/5594631df3b3512adecea0f5... Michal