# HG changeset patch
# User Keir Fraser <keir.fraser@xxxxxxxxxx>
# Date 1208953749 -3600
# Node ID 86b8417db325d2a82b48eedfc7c962ff9ae9dffd
# Parent bc7ee2f93852b0ac1e644a5604dda223f12b8604
ACM: Put hash of XML policy into binary policy to tie them together
This patch extends the ACM binary policy format with an embedded hash
of the corresponding XML policy in order to tie them together. This
allows xend to determine whether it has the correct XML policy in its
repository and react appropriately if it does not have it.
Signed-off-by: Stefan Berger <stefanb@xxxxxxxxxx>
---
tools/python/xen/util/acmpolicy.py | 27 ++++++++++++++++++++++++---
tools/python/xen/xend/XendXSPolicyAdmin.py | 1 +
xen/include/public/xsm/acm.h | 7 ++++++-
xen/include/xsm/acm/acm_core.h | 1 +
xen/xsm/acm/acm_policy.c | 8 ++++++++
5 files changed, 40 insertions(+), 4 deletions(-)
diff -r bc7ee2f93852 -r 86b8417db325 tools/python/xen/util/acmpolicy.py
--- a/tools/python/xen/util/acmpolicy.py Wed Apr 23 13:32:58 2008 +0100
+++ b/tools/python/xen/util/acmpolicy.py Wed Apr 23 13:29:09 2008 +0100
@@ -17,6 +17,7 @@
#============================================================================
import os
+import sha
import stat
import array
import struct
@@ -35,7 +36,7 @@ ACM_POLICIES_DIR = security.policy_dir_p
# Constants needed for generating a binary policy from its XML
# representation
-ACM_POLICY_VERSION = 3 # Latest one
+ACM_POLICY_VERSION = 4 # Latest one
ACM_CHWALL_VERSION = 1
ACM_STE_VERSION = 1
@@ -965,6 +966,10 @@ class ACMPolicy(XSPolicy):
return dom.toxml()
return None
+ def hash(self):
+ """ Calculate a SAH1 hash of the XML policy """
+ return sha.sha(self.toxml())
+
def save(self):
### Save the XML policy into a file ###
rc = -xsconstants.XSERR_FILE_ERROR
@@ -1403,7 +1408,7 @@ class ACMPolicy(XSPolicy):
ste_bin += "\x00"
#Write binary header:
- headerformat="!iiiiiiiiii"
+ headerformat="!iiiiiiiiii20s"
totallen_bin = struct.calcsize(headerformat) + \
len(pr_bin) + len(chw_bin) + len(ste_bin)
polref_offset = struct.calcsize(headerformat)
@@ -1425,7 +1430,8 @@ class ACMPolicy(XSPolicy):
primpoloffset,
secpolcode,
secpoloffset,
- major, minor)
+ major, minor,
+ self.hash().digest())
all_bin = array.array('B')
for s in [ hdr_bin, pr_bin, chw_bin, ste_bin ]:
@@ -1443,6 +1449,21 @@ class ACMPolicy(XSPolicy):
rc = -xsconstants.XSERR_BAD_LABEL
return rc, mapfile, all_bin.tostring()
+ def validate_enforced_policy_hash(self):
+ """ verify that the policy hash embedded in the binary policy
+ that is currently enforce matches the one of the XML policy.
+ """
+ if self.hash().digest() != self.get_enforced_policy_hash():
+ raise Exception('Policy hashes do not match')
+
+ def get_enforced_policy_hash(self):
+ binpol = self.get_enforced_binary()
+ headerformat="!iiiiiiiiii20s"
+ res = struct.unpack(headerformat, binpol[:60])
+ if len(res) >= 11:
+ return res[10]
+ return None
+
def get_enforced_binary(self):
rc, binpol = security.hv_get_policy()
if rc != 0:
diff -r bc7ee2f93852 -r 86b8417db325 tools/python/xen/xend/XendXSPolicyAdmin.py
--- a/tools/python/xen/xend/XendXSPolicyAdmin.py Wed Apr 23 13:32:58
2008 +0100
+++ b/tools/python/xen/xend/XendXSPolicyAdmin.py Wed Apr 23 13:29:09
2008 +0100
@@ -54,6 +54,7 @@ class XSPolicyAdmin:
try:
self.xsobjs[ref] = ACMPolicy(name=act_pol_name, ref=ref)
self.policies[ref] = (act_pol_name, xsconstants.ACM_POLICY_ID)
+ self.xsobjs[ref].validate_enforced_policy_hash()
except Exception, e:
log.error("Could not find XML representation of policy '%s': "
"%s" % (act_pol_name,e))
diff -r bc7ee2f93852 -r 86b8417db325 xen/include/public/xsm/acm.h
--- a/xen/include/public/xsm/acm.h Wed Apr 23 13:32:58 2008 +0100
+++ b/xen/include/public/xsm/acm.h Wed Apr 23 13:29:09 2008 +0100
@@ -91,7 +91,7 @@
* whenever the interpretation of the related
* policy's data structure changes
*/
-#define ACM_POLICY_VERSION 3
+#define ACM_POLICY_VERSION 4
#define ACM_CHWALL_VERSION 1
#define ACM_STE_VERSION 1
@@ -131,6 +131,10 @@ typedef uint16_t domaintype_t;
/* high-16 = version, low-16 = check magic */
#define ACM_MAGIC 0x0001debc
+/* size of the SHA1 hash identifying the XML policy from which the
+ binary policy was created */
+#define ACM_SHA1_HASH_SIZE 20
+
/* each offset in bytes from start of the struct they
* are part of */
@@ -160,6 +164,7 @@ struct acm_policy_buffer {
uint32_t secondary_policy_code;
uint32_t secondary_buffer_offset;
struct acm_policy_version xml_pol_version; /* add in V3 */
+ uint8_t xml_policy_hash[ACM_SHA1_HASH_SIZE]; /* added in V4 */
};
diff -r bc7ee2f93852 -r 86b8417db325 xen/include/xsm/acm/acm_core.h
--- a/xen/include/xsm/acm/acm_core.h Wed Apr 23 13:32:58 2008 +0100
+++ b/xen/include/xsm/acm/acm_core.h Wed Apr 23 13:29:09 2008 +0100
@@ -34,6 +34,7 @@ struct acm_binary_policy {
u16 primary_policy_code;
u16 secondary_policy_code;
struct acm_policy_version xml_pol_version;
+ u8 xml_policy_hash[ACM_SHA1_HASH_SIZE];
};
struct chwall_binary_policy {
diff -r bc7ee2f93852 -r 86b8417db325 xen/xsm/acm/acm_policy.c
--- a/xen/xsm/acm/acm_policy.c Wed Apr 23 13:32:58 2008 +0100
+++ b/xen/xsm/acm/acm_policy.c Wed Apr 23 13:29:09 2008 +0100
@@ -156,6 +156,10 @@ _acm_update_policy(void *buf, u32 buf_si
&pol->xml_pol_version,
sizeof(acm_bin_pol.xml_pol_version));
+ memcpy(&acm_bin_pol.xml_policy_hash,
+ pol->xml_policy_hash,
+ sizeof(acm_bin_pol.xml_policy_hash));
+
if ( acm_primary_ops->is_default_policy() &&
acm_secondary_ops->is_default_policy() )
require_update = 0;
@@ -257,6 +261,10 @@ acm_get_policy(XEN_GUEST_HANDLE_64(void)
memcpy(&bin_pol->xml_pol_version,
&acm_bin_pol.xml_pol_version,
sizeof(struct acm_policy_version));
+
+ memcpy(&bin_pol->xml_policy_hash,
+ &acm_bin_pol.xml_policy_hash,
+ sizeof(acm_bin_pol.xml_policy_hash));
ret = acm_dump_policy_reference(
policy_buffer + be32_to_cpu(bin_pol->policy_reference_offset),
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