Mailing List Archive

Allow a domain to be built under one security label and run using a
different label. This can be used to prevent the domain builder or
control domain from having the ability to access a guest domain's memory
via map_foreign_range except during the build process where this is
required.

Note: this does not provide complete protection from a malicious dom0;
mappings created during the build process may persist after the relabel,
and could be used to indirectly access the guest's memory.

Signed-off-by: Daniel De Graaf <dgdegra@tycho.nsa.gov>
Cc: Ian Jackson <ian.jackson@eu.citrix.com>
Cc: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Cc: Ian Campbell <ian.campbell@citrix.com>
---
tools/libxc/xc_flask.c | 10 ++++++++++
tools/libxc/xenctrl.h | 1 +
tools/libxl/libxl_create.c | 4 ++++
tools/libxl/libxl_types.idl | 1 +
tools/libxl/xl_cmdimpl.c | 20 +++++++++++++++++++-
5 files changed, 35 insertions(+), 1 deletion(-)

diff --git a/tools/libxc/xc_flask.c b/tools/libxc/xc_flask.c
index 80c5a2d..face1e0 100644
--- a/tools/libxc/xc_flask.c
+++ b/tools/libxc/xc_flask.c
@@ -422,6 +422,16 @@ int xc_flask_setavc_threshold(xc_interface *xch, int threshold)
return xc_flask_op(xch, &op);
}

+int xc_flask_relabel_domain(xc_interface *xch, int domid, uint32_t sid)
+{
+ DECLARE_FLASK_OP;
+ op.cmd = FLASK_RELABEL_DOMAIN;
+ op.u.relabel.domid = domid;
+ op.u.relabel.sid = sid;
+
+ return xc_flask_op(xch, &op);
+}
+
/*
* Local variables:
* mode: C
diff --git a/tools/libxc/xenctrl.h b/tools/libxc/xenctrl.h
index 7eb5743..60391c6 100644
--- a/tools/libxc/xenctrl.h
+++ b/tools/libxc/xenctrl.h
@@ -2158,6 +2158,7 @@ int xc_flask_policyvers(xc_interface *xc_handle);
int xc_flask_avc_hashstats(xc_interface *xc_handle, char *buf, int size);
int xc_flask_getavc_threshold(xc_interface *xc_handle);
int xc_flask_setavc_threshold(xc_interface *xc_handle, int threshold);
+int xc_flask_relabel_domain(xc_interface *xch, int domid, uint32_t sid);

struct elf_binary;
void xc_elf_set_logfile(xc_interface *xch, struct elf_binary *elf,
diff --git a/tools/libxl/libxl_create.c b/tools/libxl/libxl_create.c
index 9d20086..b183255 100644
--- a/tools/libxl/libxl_create.c
+++ b/tools/libxl/libxl_create.c
@@ -1182,6 +1182,10 @@ static void domcreate_complete(libxl__egc *egc,
int rc)
{
STATE_AO_GC(dcs->ao);
+ libxl_domain_config *const d_config = dcs->guest_config;
+
+ if (!rc && d_config->b_info.exec_ssidref)
+ rc = xc_flask_relabel_domain(CTX->xch, dcs->guest_domid, d_config->b_info.exec_ssidref);

if (rc) {
if (dcs->guest_domid) {
diff --git a/tools/libxl/libxl_types.idl b/tools/libxl/libxl_types.idl
index 7eac4a8..93524f0 100644
--- a/tools/libxl/libxl_types.idl
+++ b/tools/libxl/libxl_types.idl
@@ -268,6 +268,7 @@ libxl_domain_build_info = Struct("domain_build_info",[
("video_memkb", MemKB),
("shadow_memkb", MemKB),
("rtc_timeoffset", uint32),
+ ("exec_ssidref", uint32),
("localtime", libxl_defbool),
("disable_migrate", libxl_defbool),
("cpuid", libxl_cpuid_policy_list),
diff --git a/tools/libxl/xl_cmdimpl.c b/tools/libxl/xl_cmdimpl.c
index 5d444a8..4d67fdf 100644
--- a/tools/libxl/xl_cmdimpl.c
+++ b/tools/libxl/xl_cmdimpl.c
@@ -596,16 +596,34 @@ static void parse_config_data(const char *config_source,
exit(1);
}

- if (!xlu_cfg_get_string (config, "seclabel", &buf, 0)) {
+ if (!xlu_cfg_get_string (config, "init_seclabel", &buf, 0)) {
e = libxl_flask_context_to_sid(ctx, (char *)buf, strlen(buf),
&c_info->ssidref);
if (e) {
if (errno == ENOSYS) {
+ fprintf(stderr, "XSM Disabled: init_seclabel not supported\n");
+ } else {
+ fprintf(stderr, "Invalid init_seclabel: %s\n", buf);
+ exit(1);
+ }
+ }
+ }
+
+ if (!xlu_cfg_get_string (config, "seclabel", &buf, 0)) {
+ uint32_t ssidref;
+ e = libxl_flask_context_to_sid(ctx, (char *)buf, strlen(buf),
+ &ssidref);
+ if (e) {
+ if (errno == ENOSYS) {
fprintf(stderr, "XSM Disabled: seclabel not supported\n");
} else {
fprintf(stderr, "Invalid seclabel: %s\n", buf);
exit(1);
}
+ } else if (c_info->ssidref) {
+ b_info->exec_ssidref = ssidref;
+ } else {
+ c_info->ssidref = ssidref;
}
}

--
1.7.11.7


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