// SPDX-License-Identifier: GPL-2.0-or-later

  /* SCTP kernel implementation

   * (C) Copyright IBM Corp. 2003, 2004
   *

   * This file is part of the SCTP kernel implementation

   *

   * This file contains the code relating the chunk abstraction.

   *

   * 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:
   *    Jon Grimm             <jgrimm@us.ibm.com>
   *    Sridhar Samudrala     <sri@us.ibm.com>

   */

  #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

  #include <linux/types.h>
  #include <linux/kernel.h>
  #include <linux/net.h>
  #include <linux/inet.h>
  #include <linux/skbuff.h>

  #include <linux/slab.h>

  #include <net/sock.h>
  #include <net/sctp/sctp.h>
  #include <net/sctp/sm.h>
  
  /* This file is mostly in anticipation of future work, but initially
   * populate with fragment tracking for an outbound message.
   */
  
  /* Initialize datamsg from memory. */
  static void sctp_datamsg_init(struct sctp_datamsg *msg)
  {

  	refcount_set(&msg->refcnt, 1);

  	msg->send_failed = 0;
  	msg->send_error = 0;

  	msg->can_delay = 1;

  	msg->abandoned = 0;

  	msg->expires_at = 0;
  	INIT_LIST_HEAD(&msg->chunks);
  }
  
  /* Allocate and initialize datamsg. */

  static struct sctp_datamsg *sctp_datamsg_new(gfp_t gfp)

  {
  	struct sctp_datamsg *msg;
  	msg = kmalloc(sizeof(struct sctp_datamsg), gfp);

  	if (msg) {

  		sctp_datamsg_init(msg);

  		SCTP_DBG_OBJCNT_INC(datamsg);
  	}

  	return msg;
  }

  void sctp_datamsg_free(struct sctp_datamsg *msg)
  {
  	struct sctp_chunk *chunk;
  
  	/* This doesn't have to be a _safe vairant because
  	 * sctp_chunk_free() only drops the refs.
  	 */
  	list_for_each_entry(chunk, &msg->chunks, frag_list)
  		sctp_chunk_free(chunk);
  
  	sctp_datamsg_put(msg);
  }

  /* Final destructruction of datamsg memory. */
  static void sctp_datamsg_destroy(struct sctp_datamsg *msg)
  {

  	struct sctp_association *asoc = NULL;

  	struct list_head *pos, *temp;
  	struct sctp_chunk *chunk;

  	struct sctp_ulpevent *ev;

  	int error, sent;

  
  	/* Release all references. */
  	list_for_each_safe(pos, temp, &msg->chunks) {
  		list_del_init(pos);
  		chunk = list_entry(pos, struct sctp_chunk, frag_list);

  
  		if (!msg->send_failed) {
  			sctp_chunk_put(chunk);
  			continue;

  		}

  		asoc = chunk->asoc;
  		error = msg->send_error ?: asoc->outqueue.error;
  		sent = chunk->has_tsn ? SCTP_DATA_SENT : SCTP_DATA_UNSENT;

  		if (sctp_ulpevent_type_enabled(asoc->subscribe,
  					       SCTP_SEND_FAILED)) {

  			ev = sctp_ulpevent_make_send_failed(asoc, chunk, sent,
  							    error, GFP_ATOMIC);
  			if (ev)

  				asoc->stream.si->enqueue_event(&asoc->ulpq, ev);

  		}

  		if (sctp_ulpevent_type_enabled(asoc->subscribe,
  					       SCTP_SEND_FAILED_EVENT)) {
  			ev = sctp_ulpevent_make_send_failed_event(asoc, chunk,
  								  sent, error,
  								  GFP_ATOMIC);
  			if (ev)
  				asoc->stream.si->enqueue_event(&asoc->ulpq, ev);
  		}

  		sctp_chunk_put(chunk);
  	}
  
  	SCTP_DBG_OBJCNT_DEC(datamsg);
  	kfree(msg);
  }
  
  /* Hold a reference. */
  static void sctp_datamsg_hold(struct sctp_datamsg *msg)
  {

  	refcount_inc(&msg->refcnt);

  }
  
  /* Release a reference. */
  void sctp_datamsg_put(struct sctp_datamsg *msg)
  {

  	if (refcount_dec_and_test(&msg->refcnt))

  		sctp_datamsg_destroy(msg);
  }

  /* Assign a chunk to this datamsg. */
  static void sctp_datamsg_assign(struct sctp_datamsg *msg, struct sctp_chunk *chunk)
  {
  	sctp_datamsg_hold(msg);
  	chunk->msg = msg;
  }
  
  
  /* A data chunk can have a maximum payload of (2^16 - 20).  Break
   * down any such message into smaller chunks.  Opportunistically, fragment
   * the chunks down to the current MTU constraints.  We may get refragmented
   * later if the PMTU changes, but it is _much better_ to fragment immediately
   * with a reasonable guess than always doing our fragmentation on the
   * soft-interrupt.
   */
  struct sctp_datamsg *sctp_datamsg_from_user(struct sctp_association *asoc,
  					    struct sctp_sndrcvinfo *sinfo,

  					    struct iov_iter *from)

  {

  	size_t len, first_len, max_data, remaining;
  	size_t msg_len = iov_iter_count(from);

  	struct sctp_shared_key *shkey = NULL;

  	struct list_head *pos, *temp;

  	struct sctp_chunk *chunk;
  	struct sctp_datamsg *msg;

  	int err;

  
  	msg = sctp_datamsg_new(GFP_KERNEL);
  	if (!msg)

  		return ERR_PTR(-ENOMEM);

  
  	/* Note: Calculate this outside of the loop, so that all fragments
  	 * have the same expiration.
  	 */

  	if (asoc->peer.prsctp_capable && sinfo->sinfo_timetolive &&
  	    (SCTP_PR_TTL_ENABLED(sinfo->sinfo_flags) ||
  	     !SCTP_PR_POLICY(sinfo->sinfo_flags)))

  		msg->expires_at = jiffies +

  				  msecs_to_jiffies(sinfo->sinfo_timetolive);

  	/* This is the biggest possible DATA chunk that can fit into
  	 * the packet
  	 */

  	max_data = asoc->frag_point;

  	if (unlikely(!max_data)) {
  		max_data = sctp_min_frag_point(sctp_sk(asoc->base.sk),
  					       sctp_datachk_len(&asoc->stream));

  		pr_warn_ratelimited("%s: asoc:%p frag_point is zero, forcing max_data to default minimum (%zu)",

  				    __func__, asoc, max_data);
  	}

  	/* If the peer requested that we authenticate DATA chunks

  	 * we need to account for bundling of the AUTH chunks along with

  	 * DATA.
  	 */
  	if (sctp_auth_send_cid(SCTP_CID_DATA, asoc)) {
  		struct sctp_hmac *hmac_desc = sctp_auth_asoc_get_hmac(asoc);
  
  		if (hmac_desc)

  			max_data -= SCTP_PAD4(sizeof(struct sctp_auth_chunk) +

  					      hmac_desc->hmac_len);

  		if (sinfo->sinfo_tsn &&
  		    sinfo->sinfo_ssn != asoc->active_key_id) {
  			shkey = sctp_auth_get_shkey(asoc, sinfo->sinfo_ssn);
  			if (!shkey) {
  				err = -EINVAL;
  				goto errout;
  			}
  		} else {
  			shkey = asoc->shkey;
  		}

  	}

  	/* Set first_len and then account for possible bundles on first frag */
  	first_len = max_data;

  	/* Check to see if we have a pending SACK and try to let it be bundled
  	 * with this message.  Do this if we don't have any data queued already.
  	 * To check that, look at out_qlen and retransmit list.
  	 * NOTE: we will not reduce to account for SACK, if the message would
  	 * not have been fragmented.
  	 */
  	if (timer_pending(&asoc->timers[SCTP_EVENT_TIMEOUT_SACK]) &&
  	    asoc->outqueue.out_qlen == 0 &&
  	    list_empty(&asoc->outqueue.retransmit) &&

  	    msg_len > max_data)

  		first_len -= SCTP_PAD4(sizeof(struct sctp_sack_chunk));

  	/* Encourage Cookie-ECHO bundling. */

  	if (asoc->state < SCTP_STATE_COOKIE_ECHOED)

  		first_len -= SCTP_ARBITRARY_COOKIE_ECHO_LEN;

  
  	/* Account for a different sized first fragment */
  	if (msg_len >= first_len) {

  		msg->can_delay = 0;

  		if (msg_len > first_len)

  			SCTP_INC_STATS(asoc->base.net,

  				       SCTP_MIB_FRAGUSRMSGS);

  	} else {
  		/* Which may be the only one... */
  		first_len = msg_len;
  	}

  	/* Create chunks for all DATA chunks. */
  	for (remaining = msg_len; remaining; remaining -= len) {
  		u8 frag = SCTP_DATA_MIDDLE_FRAG;

  		if (remaining == msg_len) {
  			/* First frag, which may also be the last */

  			frag |= SCTP_DATA_FIRST_FRAG;

  			len = first_len;
  		} else {
  			/* Middle frags */
  			len = max_data;
  		}

  		if (len >= remaining) {
  			/* Last frag, which may also be the first */
  			len = remaining;

  			frag |= SCTP_DATA_LAST_FRAG;

  			/* The application requests to set the I-bit of the
  			 * last DATA chunk of a user message when providing
  			 * the user message to the SCTP implementation.
  			 */
  			if ((sinfo->sinfo_flags & SCTP_EOF) ||
  			    (sinfo->sinfo_flags & SCTP_SACK_IMMEDIATELY))
  				frag |= SCTP_DATA_SACK_IMM;
  		}

  		chunk = asoc->stream.si->make_datafrag(asoc, sinfo, len, frag,
  						       GFP_KERNEL);

  		if (!chunk) {
  			err = -ENOMEM;

  			goto errout;

  		}

  		err = sctp_user_addto_chunk(chunk, len, from);

  		if (err < 0)

  			goto errout_chunk_free;

  		chunk->shkey = shkey;

  		/* Put the chunk->skb back into the form expected by send.  */

  		__skb_pull(chunk->skb, (__u8 *)chunk->chunk_hdr -
  				       chunk->skb->data);

  
  		sctp_datamsg_assign(msg, chunk);
  		list_add_tail(&chunk->frag_list, &msg->chunks);
  	}
  
  	return msg;

  errout_chunk_free:
  	sctp_chunk_free(chunk);

  errout:
  	list_for_each_safe(pos, temp, &msg->chunks) {
  		list_del_init(pos);
  		chunk = list_entry(pos, struct sctp_chunk, frag_list);
  		sctp_chunk_free(chunk);
  	}

  	sctp_datamsg_put(msg);

  	return ERR_PTR(err);

  }
  
  /* Check whether this message has expired. */
  int sctp_chunk_abandoned(struct sctp_chunk *chunk)
  {

  	if (!chunk->asoc->peer.prsctp_capable)

  		return 0;

  	if (chunk->msg->abandoned)
  		return 1;

  	if (!chunk->has_tsn &&
  	    !(chunk->chunk_hdr->flags & SCTP_DATA_FIRST_FRAG))
  		return 0;

  	if (SCTP_PR_TTL_ENABLED(chunk->sinfo.sinfo_flags) &&

  	    time_after(jiffies, chunk->msg->expires_at)) {

  		struct sctp_stream_out *streamout =

  			SCTP_SO(&chunk->asoc->stream,
  				chunk->sinfo.sinfo_stream);

  
  		if (chunk->sent_count) {

  			chunk->asoc->abandoned_sent[SCTP_PR_INDEX(TTL)]++;

  			streamout->ext->abandoned_sent[SCTP_PR_INDEX(TTL)]++;

  		} else {

  			chunk->asoc->abandoned_unsent[SCTP_PR_INDEX(TTL)]++;

  			streamout->ext->abandoned_unsent[SCTP_PR_INDEX(TTL)]++;

  		}

  		chunk->msg->abandoned = 1;

  		return 1;

  	} else if (SCTP_PR_RTX_ENABLED(chunk->sinfo.sinfo_flags) &&

  		   chunk->sent_count > chunk->sinfo.sinfo_timetolive) {

  		struct sctp_stream_out *streamout =

  			SCTP_SO(&chunk->asoc->stream,
  				chunk->sinfo.sinfo_stream);

  		chunk->asoc->abandoned_sent[SCTP_PR_INDEX(RTX)]++;

  		streamout->ext->abandoned_sent[SCTP_PR_INDEX(RTX)]++;

  		chunk->msg->abandoned = 1;

  		return 1;

  	} else if (!SCTP_PR_POLICY(chunk->sinfo.sinfo_flags) &&
  		   chunk->msg->expires_at &&
  		   time_after(jiffies, chunk->msg->expires_at)) {

  		chunk->msg->abandoned = 1;

  		return 1;

  	}

  	/* PRIO policy is processed by sendmsg, not here */

  
  	return 0;
  }
  
  /* This chunk (and consequently entire message) has failed in its sending. */
  void sctp_chunk_fail(struct sctp_chunk *chunk, int error)
  {
  	chunk->msg->send_failed = 1;
  	chunk->msg->send_error = error;
  }