1 files changed, 364 insertions, 0 deletions

diff --git a/net/sctp/tsnmap.c b/net/sctp/tsnmap.c
new file mode 100644
index 000000000..a9c6af579
--- /dev/null
+++ b/net/sctp/tsnmap.c
@@ -0,0 +1,364 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/* SCTP kernel implementation
+ * (C) Copyright IBM Corp. 2001, 2004
+ * Copyright (c) 1999-2000 Cisco, Inc.
+ * Copyright (c) 1999-2001 Motorola, Inc.
+ * Copyright (c) 2001 Intel Corp.
+ *
+ * This file is part of the SCTP kernel implementation
+ *
+ * These functions manipulate sctp tsn mapping array.
+ *
+ * Please send any bug reports or fixes you make to the
+ * email address(es):
+ *    lksctp developers <linux-sctp@vger.kernel.org>
+ *
+ * Written or modified by:
+ *    La Monte H.P. Yarroll <piggy@acm.org>
+ *    Jon Grimm             <jgrimm@us.ibm.com>
+ *    Karl Knutson          <karl@athena.chicago.il.us>
+ *    Sridhar Samudrala     <sri@us.ibm.com>
+ */
+
+#include <linux/slab.h>
+#include <linux/types.h>
+#include <linux/bitmap.h>
+#include <net/sctp/sctp.h>
+#include <net/sctp/sm.h>
+
+static void sctp_tsnmap_update(struct sctp_tsnmap *map);
+static void sctp_tsnmap_find_gap_ack(unsigned long *map, __u16 off,
+				     __u16 len, __u16 *start, __u16 *end);
+static int sctp_tsnmap_grow(struct sctp_tsnmap *map, u16 size);
+
+/* Initialize a block of memory as a tsnmap.  */
+struct sctp_tsnmap *sctp_tsnmap_init(struct sctp_tsnmap *map, __u16 len,
+				     __u32 initial_tsn, gfp_t gfp)
+{
+	if (!map->tsn_map) {
+		map->tsn_map = kzalloc(len>>3, gfp);
+		if (map->tsn_map == NULL)
+			return NULL;
+
+		map->len = len;
+	} else {
+		bitmap_zero(map->tsn_map, map->len);
+	}
+
+	/* Keep track of TSNs represented by tsn_map.  */
+	map->base_tsn = initial_tsn;
+	map->cumulative_tsn_ack_point = initial_tsn - 1;
+	map->max_tsn_seen = map->cumulative_tsn_ack_point;
+	map->num_dup_tsns = 0;
+
+	return map;
+}
+
+void sctp_tsnmap_free(struct sctp_tsnmap *map)
+{
+	map->len = 0;
+	kfree(map->tsn_map);
+}
+
+/* Test the tracking state of this TSN.
+ * Returns:
+ *   0 if the TSN has not yet been seen
+ *  >0 if the TSN has been seen (duplicate)
+ *  <0 if the TSN is invalid (too large to track)
+ */
+int sctp_tsnmap_check(const struct sctp_tsnmap *map, __u32 tsn)
+{
+	u32 gap;
+
+	/* Check to see if this is an old TSN */
+	if (TSN_lte(tsn, map->cumulative_tsn_ack_point))
+		return 1;
+
+	/* Verify that we can hold this TSN and that it will not
+	 * overlfow our map
+	 */
+	if (!TSN_lt(tsn, map->base_tsn + SCTP_TSN_MAP_SIZE))
+		return -1;
+
+	/* Calculate the index into the mapping arrays.  */
+	gap = tsn - map->base_tsn;
+
+	/* Check to see if TSN has already been recorded.  */
+	if (gap < map->len && test_bit(gap, map->tsn_map))
+		return 1;
+	else
+		return 0;
+}
+
+
+/* Mark this TSN as seen.  */
+int sctp_tsnmap_mark(struct sctp_tsnmap *map, __u32 tsn,
+		     struct sctp_transport *trans)
+{
+	u16 gap;
+
+	if (TSN_lt(tsn, map->base_tsn))
+		return 0;
+
+	gap = tsn - map->base_tsn;
+
+	if (gap >= map->len && !sctp_tsnmap_grow(map, gap + 1))
+		return -ENOMEM;
+
+	if (!sctp_tsnmap_has_gap(map) && gap == 0) {
+		/* In this case the map has no gaps and the tsn we are
+		 * recording is the next expected tsn.  We don't touch
+		 * the map but simply bump the values.
+		 */
+		map->max_tsn_seen++;
+		map->cumulative_tsn_ack_point++;
+		if (trans)
+			trans->sack_generation =
+				trans->asoc->peer.sack_generation;
+		map->base_tsn++;
+	} else {
+		/* Either we already have a gap, or about to record a gap, so
+		 * have work to do.
+		 *
+		 * Bump the max.
+		 */
+		if (TSN_lt(map->max_tsn_seen, tsn))
+			map->max_tsn_seen = tsn;
+
+		/* Mark the TSN as received.  */
+		set_bit(gap, map->tsn_map);
+
+		/* Go fixup any internal TSN mapping variables including
+		 * cumulative_tsn_ack_point.
+		 */
+		sctp_tsnmap_update(map);
+	}
+
+	return 0;
+}
+
+
+/* Initialize a Gap Ack Block iterator from memory being provided.  */
+static void sctp_tsnmap_iter_init(const struct sctp_tsnmap *map,
+				  struct sctp_tsnmap_iter *iter)
+{
+	/* Only start looking one past the Cumulative TSN Ack Point.  */
+	iter->start = map->cumulative_tsn_ack_point + 1;
+}
+
+/* Get the next Gap Ack Blocks. Returns 0 if there was not another block
+ * to get.
+ */
+static int sctp_tsnmap_next_gap_ack(const struct sctp_tsnmap *map,
+				    struct sctp_tsnmap_iter *iter,
+				    __u16 *start, __u16 *end)
+{
+	int ended = 0;
+	__u16 start_ = 0, end_ = 0, offset;
+
+	/* If there are no more gap acks possible, get out fast.  */
+	if (TSN_lte(map->max_tsn_seen, iter->start))
+		return 0;
+
+	offset = iter->start - map->base_tsn;
+	sctp_tsnmap_find_gap_ack(map->tsn_map, offset, map->len,
+				 &start_, &end_);
+
+	/* The Gap Ack Block happens to end at the end of the map. */
+	if (start_ && !end_)
+		end_ = map->len - 1;
+
+	/* If we found a Gap Ack Block, return the start and end and
+	 * bump the iterator forward.
+	 */
+	if (end_) {
+		/* Fix up the start and end based on the
+		 * Cumulative TSN Ack which is always 1 behind base.
+		 */
+		*start = start_ + 1;
+		*end = end_ + 1;
+
+		/* Move the iterator forward.  */
+		iter->start = map->cumulative_tsn_ack_point + *end + 1;
+		ended = 1;
+	}
+
+	return ended;
+}
+
+/* Mark this and any lower TSN as seen.  */
+void sctp_tsnmap_skip(struct sctp_tsnmap *map, __u32 tsn)
+{
+	u32 gap;
+
+	if (TSN_lt(tsn, map->base_tsn))
+		return;
+	if (!TSN_lt(tsn, map->base_tsn + SCTP_TSN_MAP_SIZE))
+		return;
+
+	/* Bump the max.  */
+	if (TSN_lt(map->max_tsn_seen, tsn))
+		map->max_tsn_seen = tsn;
+
+	gap = tsn - map->base_tsn + 1;
+
+	map->base_tsn += gap;
+	map->cumulative_tsn_ack_point += gap;
+	if (gap >= map->len) {
+		/* If our gap is larger then the map size, just
+		 * zero out the map.
+		 */
+		bitmap_zero(map->tsn_map, map->len);
+	} else {
+		/* If the gap is smaller than the map size,
+		 * shift the map by 'gap' bits and update further.
+		 */
+		bitmap_shift_right(map->tsn_map, map->tsn_map, gap, map->len);
+		sctp_tsnmap_update(map);
+	}
+}
+
+/********************************************************************
+ * 2nd Level Abstractions
+ ********************************************************************/
+
+/* This private helper function updates the tsnmap buffers and
+ * the Cumulative TSN Ack Point.
+ */
+static void sctp_tsnmap_update(struct sctp_tsnmap *map)
+{
+	u16 len;
+	unsigned long zero_bit;
+
+
+	len = map->max_tsn_seen - map->cumulative_tsn_ack_point;
+	zero_bit = find_first_zero_bit(map->tsn_map, len);
+	if (!zero_bit)
+		return;		/* The first 0-bit is bit 0.  nothing to do */
+
+	map->base_tsn += zero_bit;
+	map->cumulative_tsn_ack_point += zero_bit;
+
+	bitmap_shift_right(map->tsn_map, map->tsn_map, zero_bit, map->len);
+}
+
+/* How many data chunks  are we missing from our peer?
+ */
+__u16 sctp_tsnmap_pending(struct sctp_tsnmap *map)
+{
+	__u32 cum_tsn = map->cumulative_tsn_ack_point;
+	__u32 max_tsn = map->max_tsn_seen;
+	__u32 base_tsn = map->base_tsn;
+	__u16 pending_data;
+	u32 gap;
+
+	pending_data = max_tsn - cum_tsn;
+	gap = max_tsn - base_tsn;
+
+	if (gap == 0 || gap >= map->len)
+		goto out;
+
+	pending_data -= bitmap_weight(map->tsn_map, gap + 1);
+out:
+	return pending_data;
+}
+
+/* This is a private helper for finding Gap Ack Blocks.  It searches a
+ * single array for the start and end of a Gap Ack Block.
+ *
+ * The flags "started" and "ended" tell is if we found the beginning
+ * or (respectively) the end of a Gap Ack Block.
+ */
+static void sctp_tsnmap_find_gap_ack(unsigned long *map, __u16 off,
+				     __u16 len, __u16 *start, __u16 *end)
+{
+	int i = off;
+
+	/* Look through the entire array, but break out
+	 * early if we have found the end of the Gap Ack Block.
+	 */
+
+	/* Also, stop looking past the maximum TSN seen. */
+
+	/* Look for the start. */
+	i = find_next_bit(map, len, off);
+	if (i < len)
+		*start = i;
+
+	/* Look for the end.  */
+	if (*start) {
+		/* We have found the start, let's find the
+		 * end.  If we find the end, break out.
+		 */
+		i = find_next_zero_bit(map, len, i);
+		if (i < len)
+			*end = i - 1;
+	}
+}
+
+/* Renege that we have seen a TSN.  */
+void sctp_tsnmap_renege(struct sctp_tsnmap *map, __u32 tsn)
+{
+	u32 gap;
+
+	if (TSN_lt(tsn, map->base_tsn))
+		return;
+	/* Assert: TSN is in range.  */
+	if (!TSN_lt(tsn, map->base_tsn + map->len))
+		return;
+
+	gap = tsn - map->base_tsn;
+
+	/* Pretend we never saw the TSN.  */
+	clear_bit(gap, map->tsn_map);
+}
+
+/* How many gap ack blocks do we have recorded? */
+__u16 sctp_tsnmap_num_gabs(struct sctp_tsnmap *map,
+			   struct sctp_gap_ack_block *gabs)
+{
+	struct sctp_tsnmap_iter iter;
+	int ngaps = 0;
+
+	/* Refresh the gap ack information. */
+	if (sctp_tsnmap_has_gap(map)) {
+		__u16 start = 0, end = 0;
+		sctp_tsnmap_iter_init(map, &iter);
+		while (sctp_tsnmap_next_gap_ack(map, &iter,
+						&start,
+						&end)) {
+
+			gabs[ngaps].start = htons(start);
+			gabs[ngaps].end = htons(end);
+			ngaps++;
+			if (ngaps >= SCTP_MAX_GABS)
+				break;
+		}
+	}
+	return ngaps;
+}
+
+static int sctp_tsnmap_grow(struct sctp_tsnmap *map, u16 size)
+{
+	unsigned long *new;
+	unsigned long inc;
+	u16  len;
+
+	if (size > SCTP_TSN_MAP_SIZE)
+		return 0;
+
+	inc = ALIGN((size - map->len), BITS_PER_LONG) + SCTP_TSN_MAP_INCREMENT;
+	len = min_t(u16, map->len + inc, SCTP_TSN_MAP_SIZE);
+
+	new = kzalloc(len>>3, GFP_ATOMIC);
+	if (!new)
+		return 0;
+
+	bitmap_copy(new, map->tsn_map,
+		map->max_tsn_seen - map->cumulative_tsn_ack_point);
+	kfree(map->tsn_map);
+	map->tsn_map = new;
+	map->len = len;
+
+	return 1;
+}