[NetLabel]: SELinux support

Add NetLabel support to the SELinux LSM and modify the
socket_post_create() LSM hook to return an error code.  The most
significant part of this patch is the addition of NetLabel hooks into
the following SELinux LSM hooks:

 * selinux_file_permission()
 * selinux_socket_sendmsg()
 * selinux_socket_post_create()
 * selinux_socket_sock_rcv_skb()
 * selinux_socket_getpeersec_stream()
 * selinux_socket_getpeersec_dgram()
 * selinux_sock_graft()
 * selinux_inet_conn_request()

The basic reasoning behind this patch is that outgoing packets are
"NetLabel'd" by labeling their socket and the NetLabel security
attributes are checked via the additional hook in
selinux_socket_sock_rcv_skb().  NetLabel itself is only a labeling
mechanism, similar to filesystem extended attributes, it is up to the
SELinux enforcement mechanism to perform the actual access checks.

In addition to the changes outlined above this patch also includes
some changes to the extended bitmap (ebitmap) and multi-level security
(mls) code to import and export SELinux TE/MLS attributes into and out
of NetLabel.

Signed-off-by: Paul Moore <paul.moore@hp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 156 insertions, 0 deletions

diff --git a/security/selinux/ss/mls.c b/security/selinux/ss/mls.c
index e15f7e0399b..119bd6078ba 100644
--- a/security/selinux/ss/mls.c
+++ b/security/selinux/ss/mls.c
@@ -10,6 +10,13 @@
  *
  * Copyright (C) 2004-2006 Trusted Computer Solutions, Inc.
  */
+/*
+ * Updated: Hewlett-Packard <paul.moore@hp.com>
+ *
+ *      Added support to import/export the MLS label
+ *
+ * (c) Copyright Hewlett-Packard Development Company, L.P., 2006
+ */
 
 #include <linux/kernel.h>
 #include <linux/slab.h>
@@ -565,3 +572,152 @@ int mls_compute_sid(struct context *scontext,
 	return -EINVAL;
 }
 
+/**
+ * mls_export_lvl - Export the MLS sensitivity levels
+ * @context: the security context
+ * @low: the low sensitivity level
+ * @high: the high sensitivity level
+ *
+ * Description:
+ * Given the security context copy the low MLS sensitivity level into lvl_low
+ * and the high sensitivity level in lvl_high.  The MLS levels are only
+ * exported if the pointers are not NULL, if they are NULL then that level is
+ * not exported.
+ *
+ */
+void mls_export_lvl(const struct context *context, u32 *low, u32 *high)
+{
+	if (!selinux_mls_enabled)
+		return;
+
+	if (low != NULL)
+		*low = context->range.level[0].sens - 1;
+	if (high != NULL)
+		*high = context->range.level[1].sens - 1;
+}
+
+/**
+ * mls_import_lvl - Import the MLS sensitivity levels
+ * @context: the security context
+ * @low: the low sensitivity level
+ * @high: the high sensitivity level
+ *
+ * Description:
+ * Given the security context and the two sensitivty levels, set the MLS levels
+ * in the context according the two given as parameters.  Returns zero on
+ * success, negative values on failure.
+ *
+ */
+void mls_import_lvl(struct context *context, u32 low, u32 high)
+{
+	if (!selinux_mls_enabled)
+		return;
+
+	context->range.level[0].sens = low + 1;
+	context->range.level[1].sens = high + 1;
+}
+
+/**
+ * mls_export_cat - Export the MLS categories
+ * @context: the security context
+ * @low: the low category
+ * @low_len: length of the cat_low bitmap in bytes
+ * @high: the high category
+ * @high_len: length of the cat_high bitmap in bytes
+ *
+ * Description:
+ * Given the security context export the low MLS category bitmap into cat_low
+ * and the high category bitmap into cat_high.  The MLS categories are only
+ * exported if the pointers are not NULL, if they are NULL then that level is
+ * not exported.  The caller is responsibile for freeing the memory when
+ * finished.  Returns zero on success, negative values on failure.
+ *
+ */
+int mls_export_cat(const struct context *context,
+		   unsigned char **low,
+		   size_t *low_len,
+		   unsigned char **high,
+		   size_t *high_len)
+{
+	int rc = -EPERM;
+
+	if (!selinux_mls_enabled)
+		return 0;
+
+	if (low != NULL) {
+		rc = ebitmap_export(&context->range.level[0].cat,
+				    low,
+				    low_len);
+		if (rc != 0)
+			goto export_cat_failure;
+	}
+	if (high != NULL) {
+		rc = ebitmap_export(&context->range.level[1].cat,
+				    high,
+				    high_len);
+		if (rc != 0)
+			goto export_cat_failure;
+	}
+
+	return 0;
+
+export_cat_failure:
+	if (low != NULL)
+		kfree(*low);
+	if (high != NULL)
+		kfree(*high);
+	return rc;
+}
+
+/**
+ * mls_import_cat - Import the MLS categories
+ * @context: the security context
+ * @low: the low category
+ * @low_len: length of the cat_low bitmap in bytes
+ * @high: the high category
+ * @high_len: length of the cat_high bitmap in bytes
+ *
+ * Description:
+ * Given the security context and the two category bitmap strings import the
+ * categories into the security context.  The MLS categories are only imported
+ * if the pointers are not NULL, if they are NULL they are skipped.  Returns
+ * zero on success, negative values on failure.
+ *
+ */
+int mls_import_cat(struct context *context,
+		   const unsigned char *low,
+		   size_t low_len,
+		   const unsigned char *high,
+		   size_t high_len)
+{
+	int rc = -EPERM;
+
+	if (!selinux_mls_enabled)
+		return 0;
+
+	if (low != NULL) {
+		rc = ebitmap_import(low,
+				    low_len,
+				    &context->range.level[0].cat);
+		if (rc != 0)
+			goto import_cat_failure;
+	}
+	if (high != NULL) {
+		if (high == low)
+			rc = ebitmap_cpy(&context->range.level[1].cat,
+					 &context->range.level[0].cat);
+		else
+			rc = ebitmap_import(high,
+					    high_len,
+					    &context->range.level[1].cat);
+		if (rc != 0)
+			goto import_cat_failure;
+	}
+
+	return 0;
+
+import_cat_failure:
+	ebitmap_destroy(&context->range.level[0].cat);
+	ebitmap_destroy(&context->range.level[1].cat);
+	return rc;
+}