SELinux: per-command whitelisting of ioctls
note that this patch depends on a prior patch that is already in
android-3.4 but has not apparently found its way into the msm 3.4
branches (but is included in exynos and tegra),
https://android-review.googlesource.com/#/c/92962/
Extend the generic ioctl permission check with support for per-command
filtering. Source/target/class sets including the ioctl permission may
additionally include a set of commands. Example:
allow <source> <target>:<class> { 0x8910-0x8926 0x892A-0x8935 }
auditallow <source> <target>:<class> 0x892A
When ioctl commands are omitted only the permissions are checked. This
feature is intended to provide finer granularity for the ioctl
permission which may be too imprecise in some circumstances. For
example, the same driver may use ioctls to provide important and
benign functionality such as driver version or socket type as well as
dangerous capabilities such as debugging features, read/write/execute
to physical memory or access to sensitive data. Per-command filtering
provides a mechanism to reduce the attack surface of the kernel, and
limit applications to the subset of commands required.
The format of the policy binary has been modified to include ioctl
commands, and the policy version number has been incremented to
POLICYDB_VERSION_IOCTL_OPERATIONS=30 to account for the format change.
Bug: 20350607
Bug: 18087110
Change-Id: Ibf0e36728f6f3f0d5af56ccdeddee40800af689d
Signed-off-by: Jeff Vander Stoep <jeffv@google.com>
diff --git a/security/selinux/ss/conditional.c b/security/selinux/ss/conditional.c
index 377d148..16651c7 100644
--- a/security/selinux/ss/conditional.c
+++ b/security/selinux/ss/conditional.c
@@ -15,6 +15,7 @@
#include "security.h"
#include "conditional.h"
+#include "services.h"
/*
* cond_evaluate_expr evaluates a conditional expr
@@ -617,21 +618,39 @@
return 0;
}
-/* Determine whether additional permissions are granted by the conditional
- * av table, and if so, add them to the result
- */
-void cond_compute_av(struct avtab *ctab, struct avtab_key *key, struct av_decision *avd)
+
+void cond_compute_operation(struct avtab *ctab, struct avtab_key *key,
+ struct operation_decision *od)
{
struct avtab_node *node;
- if (!ctab || !key || !avd)
+ if (!ctab || !key || !od)
+ return;
+
+ for (node = avtab_search_node(ctab, key); node;
+ node = avtab_search_node_next(node, key->specified)) {
+ if (node->key.specified & AVTAB_ENABLED)
+ services_compute_operation_num(od, node);
+ }
+ return;
+
+}
+/* Determine whether additional permissions are granted by the conditional
+ * av table, and if so, add them to the result
+ */
+void cond_compute_av(struct avtab *ctab, struct avtab_key *key,
+ struct av_decision *avd, struct operation *ops)
+{
+ struct avtab_node *node;
+
+ if (!ctab || !key || !avd || !ops)
return;
for (node = avtab_search_node(ctab, key); node;
node = avtab_search_node_next(node, key->specified)) {
if ((u16)(AVTAB_ALLOWED|AVTAB_ENABLED) ==
(node->key.specified & (AVTAB_ALLOWED|AVTAB_ENABLED)))
- avd->allowed |= node->datum.data;
+ avd->allowed |= node->datum.u.data;
if ((u16)(AVTAB_AUDITDENY|AVTAB_ENABLED) ==
(node->key.specified & (AVTAB_AUDITDENY|AVTAB_ENABLED)))
/* Since a '0' in an auditdeny mask represents a
@@ -639,10 +658,13 @@
* the '&' operand to ensure that all '0's in the mask
* are retained (much unlike the allow and auditallow cases).
*/
- avd->auditdeny &= node->datum.data;
+ avd->auditdeny &= node->datum.u.data;
if ((u16)(AVTAB_AUDITALLOW|AVTAB_ENABLED) ==
(node->key.specified & (AVTAB_AUDITALLOW|AVTAB_ENABLED)))
- avd->auditallow |= node->datum.data;
+ avd->auditallow |= node->datum.u.data;
+ if ((node->key.specified & AVTAB_ENABLED) &&
+ (node->key.specified & AVTAB_OP))
+ services_compute_operation_type(ops, node);
}
return;
}