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-rw-r--r--security/selinux/ss/services.c85
1 files changed, 85 insertions, 0 deletions
diff --git a/security/selinux/ss/services.c b/security/selinux/ss/services.c
index 8ee04a424df7..7f0ee1b91e1d 100644
--- a/security/selinux/ss/services.c
+++ b/security/selinux/ss/services.c
@@ -2054,6 +2054,91 @@ out:
return rc;
}
+/**
+ * security_net_peersid_resolve - Compare and resolve two network peer SIDs
+ * @nlbl_sid: NetLabel SID
+ * @nlbl_type: NetLabel labeling protocol type
+ * @xfrm_sid: XFRM SID
+ *
+ * Description:
+ * Compare the @nlbl_sid and @xfrm_sid values and if the two SIDs can be
+ * resolved into a single SID it is returned via @peer_sid and the function
+ * returns zero. Otherwise @peer_sid is set to SECSID_NULL and the function
+ * returns a negative value. A table summarizing the behavior is below:
+ *
+ * | function return | @sid
+ * ------------------------------+-----------------+-----------------
+ * no peer labels | 0 | SECSID_NULL
+ * single peer label | 0 | <peer_label>
+ * multiple, consistent labels | 0 | <peer_label>
+ * multiple, inconsistent labels | -<errno> | SECSID_NULL
+ *
+ */
+int security_net_peersid_resolve(u32 nlbl_sid, u32 nlbl_type,
+ u32 xfrm_sid,
+ u32 *peer_sid)
+{
+ int rc;
+ struct context *nlbl_ctx;
+ struct context *xfrm_ctx;
+
+ /* handle the common (which also happens to be the set of easy) cases
+ * right away, these two if statements catch everything involving a
+ * single or absent peer SID/label */
+ if (xfrm_sid == SECSID_NULL) {
+ *peer_sid = nlbl_sid;
+ return 0;
+ }
+ /* NOTE: an nlbl_type == NETLBL_NLTYPE_UNLABELED is a "fallback" label
+ * and is treated as if nlbl_sid == SECSID_NULL when a XFRM SID/label
+ * is present */
+ if (nlbl_sid == SECSID_NULL || nlbl_type == NETLBL_NLTYPE_UNLABELED) {
+ *peer_sid = xfrm_sid;
+ return 0;
+ }
+
+ /* we don't need to check ss_initialized here since the only way both
+ * nlbl_sid and xfrm_sid are not equal to SECSID_NULL would be if the
+ * security server was initialized and ss_initialized was true */
+ if (!selinux_mls_enabled) {
+ *peer_sid = SECSID_NULL;
+ return 0;
+ }
+
+ POLICY_RDLOCK;
+
+ nlbl_ctx = sidtab_search(&sidtab, nlbl_sid);
+ if (!nlbl_ctx) {
+ printk(KERN_ERR
+ "security_sid_mls_cmp: unrecognized SID %d\n",
+ nlbl_sid);
+ rc = -EINVAL;
+ goto out_slowpath;
+ }
+ xfrm_ctx = sidtab_search(&sidtab, xfrm_sid);
+ if (!xfrm_ctx) {
+ printk(KERN_ERR
+ "security_sid_mls_cmp: unrecognized SID %d\n",
+ xfrm_sid);
+ rc = -EINVAL;
+ goto out_slowpath;
+ }
+ rc = (mls_context_cmp(nlbl_ctx, xfrm_ctx) ? 0 : -EACCES);
+
+out_slowpath:
+ POLICY_RDUNLOCK;
+ if (rc == 0)
+ /* at present NetLabel SIDs/labels really only carry MLS
+ * information so if the MLS portion of the NetLabel SID
+ * matches the MLS portion of the labeled XFRM SID/label
+ * then pass along the XFRM SID as it is the most
+ * expressive */
+ *peer_sid = xfrm_sid;
+ else
+ *peer_sid = SECSID_NULL;
+ return rc;
+}
+
static int get_classes_callback(void *k, void *d, void *args)
{
struct class_datum *datum = d;