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, 201 insertions, 0 deletions

diff --git a/net/netlabel/netlabel_kapi.c b/net/netlabel/netlabel_kapi.c
index b35ebf9..e03a328 100644
--- a/net/netlabel/netlabel_kapi.c
+++ b/net/netlabel/netlabel_kapi.c
@@ -40,6 +40,207 @@
 #include "netlabel_user.h"
 
 /*
+ * Security Attribute Functions
+ */
+
+/**
+ * netlbl_secattr_catmap_walk - Walk a LSM secattr catmap looking for a bit
+ * @catmap: the category bitmap
+ * @offset: the offset to start searching at, in bits
+ *
+ * Description:
+ * This function walks a LSM secattr category bitmap starting at @offset and
+ * returns the spot of the first set bit or -ENOENT if no bits are set.
+ *
+ */
+int netlbl_secattr_catmap_walk(struct netlbl_lsm_secattr_catmap *catmap,
+			       u32 offset)
+{
+	struct netlbl_lsm_secattr_catmap *iter = catmap;
+	u32 node_idx;
+	u32 node_bit;
+	NETLBL_CATMAP_MAPTYPE bitmap;
+
+	if (offset > iter->startbit) {
+		while (offset >= (iter->startbit + NETLBL_CATMAP_SIZE)) {
+			iter = iter->next;
+			if (iter == NULL)
+				return -ENOENT;
+		}
+		node_idx = (offset - iter->startbit) / NETLBL_CATMAP_MAPSIZE;
+		node_bit = offset - iter->startbit -
+			   (NETLBL_CATMAP_MAPSIZE * node_idx);
+	} else {
+		node_idx = 0;
+		node_bit = 0;
+	}
+	bitmap = iter->bitmap[node_idx] >> node_bit;
+
+	for (;;) {
+		if (bitmap != 0) {
+			while ((bitmap & NETLBL_CATMAP_BIT) == 0) {
+				bitmap >>= 1;
+				node_bit++;
+			}
+			return iter->startbit +
+				(NETLBL_CATMAP_MAPSIZE * node_idx) + node_bit;
+		}
+		if (++node_idx >= NETLBL_CATMAP_MAPCNT) {
+			if (iter->next != NULL) {
+				iter = iter->next;
+				node_idx = 0;
+			} else
+				return -ENOENT;
+		}
+		bitmap = iter->bitmap[node_idx];
+		node_bit = 0;
+	}
+
+	return -ENOENT;
+}
+
+/**
+ * netlbl_secattr_catmap_walk_rng - Find the end of a string of set bits
+ * @catmap: the category bitmap
+ * @offset: the offset to start searching at, in bits
+ *
+ * Description:
+ * This function walks a LSM secattr category bitmap starting at @offset and
+ * returns the spot of the first cleared bit or -ENOENT if the offset is past
+ * the end of the bitmap.
+ *
+ */
+int netlbl_secattr_catmap_walk_rng(struct netlbl_lsm_secattr_catmap *catmap,
+				   u32 offset)
+{
+	struct netlbl_lsm_secattr_catmap *iter = catmap;
+	u32 node_idx;
+	u32 node_bit;
+	NETLBL_CATMAP_MAPTYPE bitmask;
+	NETLBL_CATMAP_MAPTYPE bitmap;
+
+	if (offset > iter->startbit) {
+		while (offset >= (iter->startbit + NETLBL_CATMAP_SIZE)) {
+			iter = iter->next;
+			if (iter == NULL)
+				return -ENOENT;
+		}
+		node_idx = (offset - iter->startbit) / NETLBL_CATMAP_MAPSIZE;
+		node_bit = offset - iter->startbit -
+			   (NETLBL_CATMAP_MAPSIZE * node_idx);
+	} else {
+		node_idx = 0;
+		node_bit = 0;
+	}
+	bitmask = NETLBL_CATMAP_BIT << node_bit;
+
+	for (;;) {
+		bitmap = iter->bitmap[node_idx];
+		while (bitmask != 0 && (bitmap & bitmask) != 0) {
+			bitmask <<= 1;
+			node_bit++;
+		}
+
+		if (bitmask != 0)
+			return iter->startbit +
+				(NETLBL_CATMAP_MAPSIZE * node_idx) +
+				node_bit - 1;
+		else if (++node_idx >= NETLBL_CATMAP_MAPCNT) {
+			if (iter->next == NULL)
+				return iter->startbit +	NETLBL_CATMAP_SIZE - 1;
+			iter = iter->next;
+			node_idx = 0;
+		}
+		bitmask = NETLBL_CATMAP_BIT;
+		node_bit = 0;
+	}
+
+	return -ENOENT;
+}
+
+/**
+ * netlbl_secattr_catmap_setbit - Set a bit in a LSM secattr catmap
+ * @catmap: the category bitmap
+ * @bit: the bit to set
+ * @flags: memory allocation flags
+ *
+ * Description:
+ * Set the bit specified by @bit in @catmap.  Returns zero on success,
+ * negative values on failure.
+ *
+ */
+int netlbl_secattr_catmap_setbit(struct netlbl_lsm_secattr_catmap *catmap,
+				 u32 bit,
+				 gfp_t flags)
+{
+	struct netlbl_lsm_secattr_catmap *iter = catmap;
+	u32 node_bit;
+	u32 node_idx;
+
+	while (iter->next != NULL &&
+	       bit >= (iter->startbit + NETLBL_CATMAP_SIZE))
+		iter = iter->next;
+	if (bit >= (iter->startbit + NETLBL_CATMAP_SIZE)) {
+		iter->next = netlbl_secattr_catmap_alloc(flags);
+		if (iter->next == NULL)
+			return -ENOMEM;
+		iter = iter->next;
+		iter->startbit = bit & ~(NETLBL_CATMAP_SIZE - 1);
+	}
+
+	/* gcc always rounds to zero when doing integer division */
+	node_idx = (bit - iter->startbit) / NETLBL_CATMAP_MAPSIZE;
+	node_bit = bit - iter->startbit - (NETLBL_CATMAP_MAPSIZE * node_idx);
+	iter->bitmap[node_idx] |= NETLBL_CATMAP_BIT << node_bit;
+
+	return 0;
+}
+
+/**
+ * netlbl_secattr_catmap_setrng - Set a range of bits in a LSM secattr catmap
+ * @catmap: the category bitmap
+ * @start: the starting bit
+ * @end: the last bit in the string
+ * @flags: memory allocation flags
+ *
+ * Description:
+ * Set a range of bits, starting at @start and ending with @end.  Returns zero
+ * on success, negative values on failure.
+ *
+ */
+int netlbl_secattr_catmap_setrng(struct netlbl_lsm_secattr_catmap *catmap,
+				 u32 start,
+				 u32 end,
+				 gfp_t flags)
+{
+	int ret_val = 0;
+	struct netlbl_lsm_secattr_catmap *iter = catmap;
+	u32 iter_max_spot;
+	u32 spot;
+
+	/* XXX - This could probably be made a bit faster by combining writes
+	 * to the catmap instead of setting a single bit each time, but for
+	 * right now skipping to the start of the range in the catmap should
+	 * be a nice improvement over calling the individual setbit function
+	 * repeatedly from a loop. */
+
+	while (iter->next != NULL &&
+	       start >= (iter->startbit + NETLBL_CATMAP_SIZE))
+		iter = iter->next;
+	iter_max_spot = iter->startbit + NETLBL_CATMAP_SIZE;
+
+	for (spot = start; spot <= end && ret_val == 0; spot++) {
+		if (spot >= iter_max_spot && iter->next != NULL) {
+			iter = iter->next;
+			iter_max_spot = iter->startbit + NETLBL_CATMAP_SIZE;
+		}
+		ret_val = netlbl_secattr_catmap_setbit(iter, spot, GFP_ATOMIC);
+	}
+
+	return ret_val;
+}
+
+/*
  * LSM Functions
  */