SELinux: allow default source/target selectors for user/role/range

When new objects are created we have great and flexible rules to
determine the type of the new object.  We aren't quite as flexible or
mature when it comes to determining the user, role, and range.  This
patch adds a new ability to specify the place a new objects user, role,
and range should come from.  For users and roles it can come from either
the source or the target of the operation.  aka for files the user can
either come from the source (the running process and todays default) or
it can come from the target (aka the parent directory of the new file)

examples always are done with
directory context: system_u:object_r:mnt_t:s0-s0:c0.c512
process context: unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023

[no rule]
	unconfined_u:object_r:mnt_t:s0   test_none
[default user source]
	unconfined_u:object_r:mnt_t:s0   test_user_source
[default user target]
	system_u:object_r:mnt_t:s0       test_user_target
[default role source]
	unconfined_u:unconfined_r:mnt_t:s0 test_role_source
[default role target]
	unconfined_u:object_r:mnt_t:s0   test_role_target
[default range source low]
	unconfined_u:object_r:mnt_t:s0 test_range_source_low
[default range source high]
	unconfined_u:object_r:mnt_t:s0:c0.c1023 test_range_source_high
[default range source low-high]
	unconfined_u:object_r:mnt_t:s0-s0:c0.c1023 test_range_source_low-high
[default range target low]
	unconfined_u:object_r:mnt_t:s0 test_range_target_low
[default range target high]
	unconfined_u:object_r:mnt_t:s0:c0.c512 test_range_target_high
[default range target low-high]
	unconfined_u:object_r:mnt_t:s0-s0:c0.c512 test_range_target_low-high

Signed-off-by: Eric Paris <eparis@redhat.com>

1 files changed, 25 insertions, 0 deletions

diff --git a/security/selinux/ss/policydb.c b/security/selinux/ss/policydb.c
index a7f61d52f05c..2bb9c2fd5f1a 100644
--- a/security/selinux/ss/policydb.c
+++ b/security/selinux/ss/policydb.c
@@ -133,6 +133,11 @@ static struct policydb_compat_info policydb_compat[] = {
                 .sym_num        = SYM_NUM,
                 .ocon_num       = OCON_NUM,
         },
+        {
+                .version        = POLICYDB_VERSION_NEW_OBJECT_DEFAULTS,
+                .sym_num        = SYM_NUM,
+                .ocon_num       = OCON_NUM,
+        },
 };
 
 static struct policydb_compat_info *policydb_lookup_compat(int version)
@@ -1306,6 +1311,16 @@ static int class_read(struct policydb *p, struct hashtab *h, void *fp)
                         goto bad;
         }
 
+        if (p->policyvers >= POLICYDB_VERSION_NEW_OBJECT_DEFAULTS) {
+                rc = next_entry(buf, fp, sizeof(u32) * 3);
+                if (rc)
+                        goto bad;
+
+                cladatum->default_user = le32_to_cpu(buf[0]);
+                cladatum->default_role = le32_to_cpu(buf[1]);
+                cladatum->default_range = le32_to_cpu(buf[2]);
+        }
+
         rc = hashtab_insert(h, key, cladatum);
         if (rc)
                 goto bad;
@@ -2832,6 +2847,16 @@ static int class_write(void *vkey, void *datum, void *ptr)
         if (rc)
                 return rc;
 
+        if (p->policyvers >= POLICYDB_VERSION_NEW_OBJECT_DEFAULTS) {
+                buf[0] = cpu_to_le32(cladatum->default_user);
+                buf[1] = cpu_to_le32(cladatum->default_role);
+                buf[2] = cpu_to_le32(cladatum->default_range);
+
+                rc = put_entry(buf, sizeof(uint32_t), 3, fp);
+                if (rc)
+                        return rc;
+        }
+
         return 0;
 }