NetLabel: convert to an extensibile/sparse category bitmap

The original NetLabel category bitmap was a straight char bitmap which worked
fine for the initial release as it only supported 240 bits due to limitations
in the CIPSO restricted bitmap tag (tag type 0x01).  This patch converts that
straight char bitmap into an extensibile/sparse bitmap in order to lay the
foundation for other CIPSO tag types and protocols.

This patch also has a nice side effect in that all of the security attributes
passed by NetLabel into the LSM are now in a format which is in the host's
native byte/bit ordering which makes the LSM specific code much simpler; look
at the changes in security/selinux/ss/ebitmap.c as an example.

Signed-off-by: Paul Moore <paul.moore@hp.com>
Signed-off-by: James Morris <jmorris@namei.org>

1 files changed, 89 insertions, 109 deletions

diff --git a/security/selinux/ss/ebitmap.c b/security/selinux/ss/ebitmap.c
index d539346ab3a..ce492a6b38e 100644
--- a/security/selinux/ss/ebitmap.c
+++ b/security/selinux/ss/ebitmap.c
@@ -6,7 +6,7 @@
 /*
  * Updated: Hewlett-Packard <paul.moore@hp.com>
  *
- *      Added ebitmap_export() and ebitmap_import()
+ *      Added support to import/export the NetLabel category bitmap
  *
  * (c) Copyright Hewlett-Packard Development Company, L.P., 2006
  */
@@ -14,6 +14,7 @@
 #include <linux/kernel.h>
 #include <linux/slab.h>
 #include <linux/errno.h>
+#include <net/netlabel.h>
 #include "ebitmap.h"
 #include "policydb.h"
 
@@ -67,141 +68,120 @@ int ebitmap_cpy(struct ebitmap *dst, struct ebitmap *src)
 	return 0;
 }
 
+#ifdef CONFIG_NETLABEL
 /**
- * ebitmap_export - Export an ebitmap to a unsigned char bitmap string
- * @src: the ebitmap to export
- * @dst: the resulting bitmap string
- * @dst_len: length of dst in bytes
+ * ebitmap_netlbl_export - Export an ebitmap into a NetLabel category bitmap
+ * @ebmap: the ebitmap to export
+ * @catmap: the NetLabel category bitmap
  *
  * Description:
- * Allocate a buffer at least src->highbit bits long and export the extensible
- * bitmap into the buffer.  The bitmap string will be in little endian format,
- * i.e. LSB first.  The value returned in dst_len may not the true size of the
- * buffer as the length of the buffer is rounded up to a multiple of MAPTYPE.
- * The caller must free the buffer when finished. Returns zero on success,
- * negative values on failure.
+ * Export a SELinux extensibile bitmap into a NetLabel category bitmap.
+ * Returns zero on success, negative values on error.
  *
  */
-int ebitmap_export(const struct ebitmap *src,
-		   unsigned char **dst,
-		   size_t *dst_len)
+int ebitmap_netlbl_export(struct ebitmap *ebmap,
+			  struct netlbl_lsm_secattr_catmap **catmap)
 {
-	size_t bitmap_len;
-	unsigned char *bitmap;
-	struct ebitmap_node *iter_node;
-	MAPTYPE node_val;
-	size_t bitmap_byte;
-	unsigned char bitmask;
-
-	if (src->highbit == 0) {
-		*dst = NULL;
-		*dst_len = 0;
+	struct ebitmap_node *e_iter = ebmap->node;
+	struct netlbl_lsm_secattr_catmap *c_iter;
+	u32 cmap_idx;
+
+	/* This function is a much simpler because SELinux's MAPTYPE happens
+	 * to be the same as NetLabel's NETLBL_CATMAP_MAPTYPE, if MAPTYPE is
+	 * changed from a u64 this function will most likely need to be changed
+	 * as well.  It's not ideal but I think the tradeoff in terms of
+	 * neatness and speed is worth it. */
+
+	if (e_iter == NULL) {
+		*catmap = NULL;
 		return 0;
 	}
 
-	bitmap_len = src->highbit / 8;
-	if (src->highbit % 7)
-		bitmap_len += 1;
-
-	bitmap = kzalloc((bitmap_len & ~(sizeof(MAPTYPE) - 1)) +
-			 sizeof(MAPTYPE),
-			 GFP_ATOMIC);
-	if (bitmap == NULL)
+	c_iter = netlbl_secattr_catmap_alloc(GFP_ATOMIC);
+	if (c_iter == NULL)
 		return -ENOMEM;
+	*catmap = c_iter;
+	c_iter->startbit = e_iter->startbit & ~(NETLBL_CATMAP_SIZE - 1);
+
+	while (e_iter != NULL) {
+		if (e_iter->startbit >=
+		    (c_iter->startbit + NETLBL_CATMAP_SIZE)) {
+			c_iter->next = netlbl_secattr_catmap_alloc(GFP_ATOMIC);
+			if (c_iter->next == NULL)
+				goto netlbl_export_failure;
+			c_iter = c_iter->next;
+			c_iter->startbit = e_iter->startbit &
+				           ~(NETLBL_CATMAP_SIZE - 1);
+		}
+		cmap_idx = (e_iter->startbit - c_iter->startbit) /
+			   NETLBL_CATMAP_MAPSIZE;
+		c_iter->bitmap[cmap_idx] = e_iter->map;
+		e_iter = e_iter->next;
+	}
 
-	iter_node = src->node;
-	do {
-		bitmap_byte = iter_node->startbit / 8;
-		bitmask = 0x80;
-		node_val = iter_node->map;
-		do {
-			if (bitmask == 0) {
-				bitmap_byte++;
-				bitmask = 0x80;
-			}
-			if (node_val & (MAPTYPE)0x01)
-				bitmap[bitmap_byte] |= bitmask;
-			node_val >>= 1;
-			bitmask >>= 1;
-		} while (node_val > 0);
-		iter_node = iter_node->next;
-	} while (iter_node);
-
-	*dst = bitmap;
-	*dst_len = bitmap_len;
 	return 0;
+
+netlbl_export_failure:
+	netlbl_secattr_catmap_free(*catmap);
+	return -ENOMEM;
 }
 
 /**
- * ebitmap_import - Import an unsigned char bitmap string into an ebitmap
- * @src: the bitmap string
- * @src_len: the bitmap length in bytes
- * @dst: the empty ebitmap
+ * ebitmap_netlbl_import - Import a NetLabel category bitmap into an ebitmap
+ * @ebmap: the ebitmap to export
+ * @catmap: the NetLabel category bitmap
  *
  * Description:
- * This function takes a little endian bitmap string in src and imports it into
- * the ebitmap pointed to by dst.  Returns zero on success, negative values on
- * failure.
+ * Import a NetLabel category bitmap into a SELinux extensibile bitmap.
+ * Returns zero on success, negative values on error.
  *
  */
-int ebitmap_import(const unsigned char *src,
-		   size_t src_len,
-		   struct ebitmap *dst)
+int ebitmap_netlbl_import(struct ebitmap *ebmap,
+			  struct netlbl_lsm_secattr_catmap *catmap)
 {
-	size_t src_off = 0;
-	size_t node_limit;
-	struct ebitmap_node *node_new;
-	struct ebitmap_node *node_last = NULL;
-	u32 i_byte;
-	u32 i_bit;
-	unsigned char src_byte;
-
-	while (src_off < src_len) {
-		if (src_len - src_off >= sizeof(MAPTYPE)) {
-			if (*(MAPTYPE *)&src[src_off] == 0) {
-				src_off += sizeof(MAPTYPE);
-				continue;
-			}
-			node_limit = sizeof(MAPTYPE);
-		} else {
-			for (src_byte = 0, i_byte = src_off;
-			     i_byte < src_len && src_byte == 0;
-			     i_byte++)
-				src_byte |= src[i_byte];
-			if (src_byte == 0)
-				break;
-			node_limit = src_len - src_off;
-		}
+	struct ebitmap_node *e_iter = NULL;
+	struct ebitmap_node *emap_prev = NULL;
+	struct netlbl_lsm_secattr_catmap *c_iter = catmap;
+	u32 c_idx;
 
-		node_new = kzalloc(sizeof(*node_new), GFP_ATOMIC);
-		if (unlikely(node_new == NULL)) {
-			ebitmap_destroy(dst);
-			return -ENOMEM;
-		}
-		node_new->startbit = src_off * 8;
-		for (i_byte = 0; i_byte < node_limit; i_byte++) {
-			src_byte = src[src_off++];
-			for (i_bit = i_byte * 8; src_byte != 0; i_bit++) {
-				if (src_byte & 0x80)
-					node_new->map |= MAPBIT << i_bit;
-				src_byte <<= 1;
-			}
-		}
+	/* This function is a much simpler because SELinux's MAPTYPE happens
+	 * to be the same as NetLabel's NETLBL_CATMAP_MAPTYPE, if MAPTYPE is
+	 * changed from a u64 this function will most likely need to be changed
+	 * as well.  It's not ideal but I think the tradeoff in terms of
+	 * neatness and speed is worth it. */
 
-		if (node_last != NULL)
-			node_last->next = node_new;
-		else
-			dst->node = node_new;
-		node_last = node_new;
-	}
+	do {
+		for (c_idx = 0; c_idx < NETLBL_CATMAP_MAPCNT; c_idx++) {
+			if (c_iter->bitmap[c_idx] == 0)
+				continue;
+
+			e_iter = kzalloc(sizeof(*e_iter), GFP_ATOMIC);
+			if (e_iter == NULL)
+				goto netlbl_import_failure;
+			if (emap_prev == NULL)
+				ebmap->node = e_iter;
+			else
+				emap_prev->next = e_iter;
+			emap_prev = e_iter;
 
-	if (likely(node_last != NULL))
-		dst->highbit = node_last->startbit + MAPSIZE;
+			e_iter->startbit = c_iter->startbit +
+				           NETLBL_CATMAP_MAPSIZE * c_idx;
+			e_iter->map = c_iter->bitmap[c_idx];
+		}
+		c_iter = c_iter->next;
+	} while (c_iter != NULL);
+	if (e_iter != NULL)
+		ebmap->highbit = e_iter->startbit + MAPSIZE;
 	else
-		ebitmap_init(dst);
+		ebitmap_destroy(ebmap);
 
 	return 0;
+
+netlbl_import_failure:
+	ebitmap_destroy(ebmap);
+	return -ENOMEM;
 }
+#endif /* CONFIG_NETLABEL */
 
 int ebitmap_contains(struct ebitmap *e1, struct ebitmap *e2)
 {