// SPDX-License-Identifier: GPL-2.0-or-later/* SCTP kernel implementation * Copyright (c) 1999-2000 Cisco, Inc. * Copyright (c) 1999-2001 Motorola, Inc. * Copyright (c) 2002 International Business Machines, Corp. * * This file is part of the SCTP kernel implementation * * These functions are the methods for accessing the SCTP inqueue. * * An SCTP inqueue is a queue into which you push SCTP packets * (which might be bundles or fragments of chunks) and out of which you * pop SCTP whole chunks. * * 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> *    Karl Knutson <karl@athena.chicago.il.us> */ #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt #include <net/sctp/sctp.h>#include <net/sctp/sm.h>#include <linux/interrupt.h>#include <linux/slab.h> /* Initialize an SCTP inqueue.  */void sctp_inq_init(struct sctp_inq *queue){	INIT_LIST_HEAD(&queue->in_chunk_list);	queue->in_progress = NULL; 	/* Create a task for delivering data.  */	INIT_WORK(&queue->immediate, NULL);} /* Properly release the chunk which is being worked on. */static inline void sctp_inq_chunk_free(struct sctp_chunk *chunk){	if (chunk->head_skb)		chunk->skb = chunk->head_skb;	sctp_chunk_free(chunk);} /* Release the memory associated with an SCTP inqueue.  */void sctp_inq_free(struct sctp_inq *queue){	struct sctp_chunk *chunk, *tmp; 	/* Empty the queue.  */	list_for_each_entry_safe(chunk, tmp, &queue->in_chunk_list, list) {		list_del_init(&chunk->list);		sctp_chunk_free(chunk);	} 	/* If there is a packet which is currently being worked on,	 * free it as well.	 */	if (queue->in_progress) {		sctp_inq_chunk_free(queue->in_progress);		queue->in_progress = NULL;	}} /* Put a new packet in an SCTP inqueue. * We assume that packet->sctp_hdr is set and in host byte order. */void sctp_inq_push(struct sctp_inq *q, struct sctp_chunk *chunk){	/* Directly call the packet handling routine.  Drop the chunk if the	 * receiver or the transport it was looked up on is gone.	 */	if (chunk->rcvr->dead ||	    (chunk->transport && chunk->transport->dead)) {		sctp_chunk_free(chunk);		return;	} 	/* We are now calling this either from the soft interrupt	 * or from the backlog processing.	 * Eventually, we should clean up inqueue to not rely	 * on the BH related data structures.	 */	list_add_tail(&chunk->list, &q->in_chunk_list);	if (chunk->asoc)		chunk->asoc->stats.ipackets++;	q->immediate.func(&q->immediate);} /* Peek at the next chunk on the inqeue. */struct sctp_chunkhdr *sctp_inq_peek(struct sctp_inq *queue){	struct sctp_chunk *chunk;	struct sctp_chunkhdr *ch = NULL; 	chunk = queue->in_progress;	/* If there is no more chunks in this packet, say so */	if (chunk->singleton ||	    chunk->end_of_packet ||	    chunk->pdiscard)		    return NULL; 	ch = (struct sctp_chunkhdr *)chunk->chunk_end; 	return ch;}  /* Extract a chunk from an SCTP inqueue. * * WARNING:  If you need to put the chunk on another queue, you need to * make a shallow copy (clone) of it. */struct sctp_chunk *sctp_inq_pop(struct sctp_inq *queue){	struct sctp_chunk *chunk;	struct sctp_chunkhdr *ch = NULL; 	/* The assumption is that we are safe to process the chunks	 * at this time.	 */ 	chunk = queue->in_progress;	if (chunk) {		/* There is a packet that we have been working on.		 * Any post processing work to do before we move on?		 */		if (chunk->singleton ||		    chunk->end_of_packet ||		    chunk->pdiscard) {			if (chunk->head_skb == chunk->skb) {				chunk->skb = skb_shinfo(chunk->skb)->frag_list;				goto new_skb;			}			if (chunk->skb->next) {				chunk->skb = chunk->skb->next;				goto new_skb;			} 			sctp_inq_chunk_free(chunk);			chunk = queue->in_progress = NULL;		} else {			/* Nothing to do. Next chunk in the packet, please. */			ch = (struct sctp_chunkhdr *)chunk->chunk_end;			/* Force chunk->skb->data to chunk->chunk_end.  */			skb_pull(chunk->skb, chunk->chunk_end - chunk->skb->data);			/* We are guaranteed to pull a SCTP header. */		}	} 	/* Do we need to take the next packet out of the queue to process? */	if (!chunk) {		struct list_head *entry; next_chunk:		/* Is the queue empty?  */		entry = sctp_list_dequeue(&queue->in_chunk_list);		if (!entry)			return NULL; 		chunk = list_entry(entry, struct sctp_chunk, list); 		if (skb_is_gso(chunk->skb) && skb_is_gso_sctp(chunk->skb)) {			/* GSO-marked skbs but without frags, handle			 * them normally			 */			if (skb_shinfo(chunk->skb)->frag_list)				chunk->head_skb = chunk->skb; 			/* skbs with "cover letter" */			if (chunk->head_skb && chunk->skb->data_len == chunk->skb->len) {				if (WARN_ON(!skb_shinfo(chunk->skb)->frag_list)) {					__SCTP_INC_STATS(dev_net(chunk->skb->dev),							 SCTP_MIB_IN_PKT_DISCARDS);					sctp_chunk_free(chunk);					goto next_chunk;				}				chunk->skb = skb_shinfo(chunk->skb)->frag_list;			}		} 		if (chunk->asoc)			sock_rps_save_rxhash(chunk->asoc->base.sk, chunk->skb); 		queue->in_progress = chunk; new_skb:		/* This is the first chunk in the packet.  */		ch = (struct sctp_chunkhdr *)chunk->skb->data;		chunk->singleton = 1;		chunk->data_accepted = 0;		chunk->pdiscard = 0;		chunk->auth = 0;		chunk->has_asconf = 0;		chunk->end_of_packet = 0;		if (chunk->head_skb) {			struct sctp_input_cb				*cb = SCTP_INPUT_CB(chunk->skb),				*head_cb = SCTP_INPUT_CB(chunk->head_skb); 			cb->chunk = head_cb->chunk;			cb->af = head_cb->af;			cb->encap_port = head_cb->encap_port;		}	} 	chunk->chunk_hdr = ch;	chunk->chunk_end = ((__u8 *)ch) + SCTP_PAD4(ntohs(ch->length));	skb_pull(chunk->skb, sizeof(*ch));	chunk->subh.v = NULL; /* Subheader is no longer valid.  */	if (unlikely(ntohs(ch->length) < sizeof(*ch))) {		chunk->pdiscard = 1;	} else if (chunk->chunk_end + sizeof(*ch) <=		   skb_tail_pointer(chunk->skb)) {		/* This is not a singleton */		chunk->singleton = 0;	} else if (chunk->chunk_end > skb_tail_pointer(chunk->skb)) {		/* Discard inside state machine. */		chunk->pdiscard = 1;		chunk->chunk_end = skb_tail_pointer(chunk->skb);	} else {		/* We are at the end of the packet, so mark the chunk		 * in case we need to send a SACK.		 */		chunk->end_of_packet = 1;	} 	pr_debug("+++sctp_inq_pop+++ chunk:%p[%s], length:%d, skb->len:%d\n",		 chunk, sctp_cname(SCTP_ST_CHUNK(chunk->chunk_hdr->type)),		 ntohs(chunk->chunk_hdr->length), chunk->skb->len); 	return chunk;} /* Set a top-half handler. * * Originally, we the top-half handler was scheduled as a BH.  We now * call the handler directly in sctp_inq_push() at a time that * we know we are lock safe. * The intent is that this routine will pull stuff out of the * inqueue and process it. */void sctp_inq_set_th_handler(struct sctp_inq *q, work_func_t callback){	INIT_WORK(&q->immediate, callback);}