// 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. * Copyright (c) 2001 Nokia, Inc. * Copyright (c) 2001 La Monte H.P. Yarroll * * This abstraction carries sctp events to the ULP (sockets). * * 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> * La Monte H.P. Yarroll <piggy@acm.org> * Sridhar Samudrala <sri@us.ibm.com> */ #include <linux/slab.h>#include <linux/types.h>#include <linux/skbuff.h>#include <net/sock.h>#include <net/busy_poll.h>#include <net/sctp/structs.h>#include <net/sctp/sctp.h>#include <net/sctp/sm.h> /* Forward declarations for internal helpers. */static struct sctp_ulpevent *sctp_ulpq_reasm(struct sctp_ulpq *ulpq, struct sctp_ulpevent *);static struct sctp_ulpevent *sctp_ulpq_order(struct sctp_ulpq *, struct sctp_ulpevent *);static void sctp_ulpq_reasm_drain(struct sctp_ulpq *ulpq); /* 1st Level Abstractions */ /* Initialize a ULP queue from a block of memory. */struct sctp_ulpq *sctp_ulpq_init(struct sctp_ulpq *ulpq, struct sctp_association *asoc){ memset(ulpq, 0, sizeof(struct sctp_ulpq)); ulpq->asoc = asoc; skb_queue_head_init(&ulpq->reasm); skb_queue_head_init(&ulpq->reasm_uo); skb_queue_head_init(&ulpq->lobby); ulpq->pd_mode = 0; return ulpq;} /* Flush the reassembly and ordering queues. */void sctp_ulpq_flush(struct sctp_ulpq *ulpq){ struct sk_buff *skb; struct sctp_ulpevent *event; while ((skb = __skb_dequeue(&ulpq->lobby)) != NULL) { event = sctp_skb2event(skb); sctp_ulpevent_free(event); } while ((skb = __skb_dequeue(&ulpq->reasm)) != NULL) { event = sctp_skb2event(skb); sctp_ulpevent_free(event); } while ((skb = __skb_dequeue(&ulpq->reasm_uo)) != NULL) { event = sctp_skb2event(skb); sctp_ulpevent_free(event); }} /* Dispose of a ulpqueue. */void sctp_ulpq_free(struct sctp_ulpq *ulpq){ sctp_ulpq_flush(ulpq);} /* Process an incoming DATA chunk. */int sctp_ulpq_tail_data(struct sctp_ulpq *ulpq, struct sctp_chunk *chunk, gfp_t gfp){ struct sk_buff_head temp; struct sctp_ulpevent *event; int event_eor = 0; /* Create an event from the incoming chunk. */ event = sctp_ulpevent_make_rcvmsg(chunk->asoc, chunk, gfp); if (!event) return -ENOMEM; event->ssn = ntohs(chunk->subh.data_hdr->ssn); event->ppid = chunk->subh.data_hdr->ppid; /* Do reassembly if needed. */ event = sctp_ulpq_reasm(ulpq, event); /* Do ordering if needed. */ if (event) { /* Create a temporary list to collect chunks on. */ skb_queue_head_init(&temp); __skb_queue_tail(&temp, sctp_event2skb(event)); if (event->msg_flags & MSG_EOR) event = sctp_ulpq_order(ulpq, event); } /* Send event to the ULP. 'event' is the sctp_ulpevent for * very first SKB on the 'temp' list. */ if (event) { event_eor = (event->msg_flags & MSG_EOR) ? 1 : 0; sctp_ulpq_tail_event(ulpq, &temp); } return event_eor;} /* Add a new event for propagation to the ULP. *//* Clear the partial delivery mode for this socket. Note: This * assumes that no association is currently in partial delivery mode. */int sctp_clear_pd(struct sock *sk, struct sctp_association *asoc){ struct sctp_sock *sp = sctp_sk(sk); if (atomic_dec_and_test(&sp->pd_mode)) { /* This means there are no other associations in PD, so * we can go ahead and clear out the lobby in one shot */ if (!skb_queue_empty(&sp->pd_lobby)) { skb_queue_splice_tail_init(&sp->pd_lobby, &sk->sk_receive_queue); return 1; } } else { /* There are other associations in PD, so we only need to * pull stuff out of the lobby that belongs to the * associations that is exiting PD (all of its notifications * are posted here). */ if (!skb_queue_empty(&sp->pd_lobby) && asoc) { struct sk_buff *skb, *tmp; struct sctp_ulpevent *event; sctp_skb_for_each(skb, &sp->pd_lobby, tmp) { event = sctp_skb2event(skb); if (event->asoc == asoc) { __skb_unlink(skb, &sp->pd_lobby); __skb_queue_tail(&sk->sk_receive_queue, skb); } } } } return 0;} /* Set the pd_mode on the socket and ulpq */static void sctp_ulpq_set_pd(struct sctp_ulpq *ulpq){ struct sctp_sock *sp = sctp_sk(ulpq->asoc->base.sk); atomic_inc(&sp->pd_mode); ulpq->pd_mode = 1;} /* Clear the pd_mode and restart any pending messages waiting for delivery. */static int sctp_ulpq_clear_pd(struct sctp_ulpq *ulpq){ ulpq->pd_mode = 0; sctp_ulpq_reasm_drain(ulpq); return sctp_clear_pd(ulpq->asoc->base.sk, ulpq->asoc);} int sctp_ulpq_tail_event(struct sctp_ulpq *ulpq, struct sk_buff_head *skb_list){ struct sock *sk = ulpq->asoc->base.sk; struct sctp_sock *sp = sctp_sk(sk); struct sctp_ulpevent *event; struct sk_buff_head *queue; struct sk_buff *skb; int clear_pd = 0; skb = __skb_peek(skb_list); event = sctp_skb2event(skb); /* If the socket is just going to throw this away, do not * even try to deliver it. */ if (sk->sk_shutdown & RCV_SHUTDOWN && (sk->sk_shutdown & SEND_SHUTDOWN || !sctp_ulpevent_is_notification(event))) goto out_free; if (!sctp_ulpevent_is_notification(event)) { sk_mark_napi_id(sk, skb); sk_incoming_cpu_update(sk); } /* Check if the user wishes to receive this event. */ if (!sctp_ulpevent_is_enabled(event, ulpq->asoc->subscribe)) goto out_free; /* If we are in partial delivery mode, post to the lobby until * partial delivery is cleared, unless, of course _this_ is * the association the cause of the partial delivery. */ if (atomic_read(&sp->pd_mode) == 0) { queue = &sk->sk_receive_queue; } else { if (ulpq->pd_mode) { /* If the association is in partial delivery, we * need to finish delivering the partially processed * packet before passing any other data. This is * because we don't truly support stream interleaving. */ if ((event->msg_flags & MSG_NOTIFICATION) || (SCTP_DATA_NOT_FRAG == (event->msg_flags & SCTP_DATA_FRAG_MASK))) queue = &sp->pd_lobby; else { clear_pd = event->msg_flags & MSG_EOR; queue = &sk->sk_receive_queue; } } else { /* * If fragment interleave is enabled, we * can queue this to the receive queue instead * of the lobby. */ if (sp->frag_interleave) queue = &sk->sk_receive_queue; else queue = &sp->pd_lobby; } } skb_queue_splice_tail_init(skb_list, queue); /* Did we just complete partial delivery and need to get * rolling again? Move pending data to the receive * queue. */ if (clear_pd) sctp_ulpq_clear_pd(ulpq); if (queue == &sk->sk_receive_queue && !sp->data_ready_signalled) { if (!sock_owned_by_user(sk)) sp->data_ready_signalled = 1; sk->sk_data_ready(sk); } return 1; out_free: if (skb_list) sctp_queue_purge_ulpevents(skb_list); else sctp_ulpevent_free(event); return 0;} /* 2nd Level Abstractions */ /* Helper function to store chunks that need to be reassembled. */static void sctp_ulpq_store_reasm(struct sctp_ulpq *ulpq, struct sctp_ulpevent *event){ struct sk_buff *pos; struct sctp_ulpevent *cevent; __u32 tsn, ctsn; tsn = event->tsn; /* See if it belongs at the end. */ pos = skb_peek_tail(&ulpq->reasm); if (!pos) { __skb_queue_tail(&ulpq->reasm, sctp_event2skb(event)); return; } /* Short circuit just dropping it at the end. */ cevent = sctp_skb2event(pos); ctsn = cevent->tsn; if (TSN_lt(ctsn, tsn)) { __skb_queue_tail(&ulpq->reasm, sctp_event2skb(event)); return; } /* Find the right place in this list. We store them by TSN. */ skb_queue_walk(&ulpq->reasm, pos) { cevent = sctp_skb2event(pos); ctsn = cevent->tsn; if (TSN_lt(tsn, ctsn)) break; } /* Insert before pos. */ __skb_queue_before(&ulpq->reasm, pos, sctp_event2skb(event)); } /* Helper function to return an event corresponding to the reassembled * datagram. * This routine creates a re-assembled skb given the first and last skb's * as stored in the reassembly queue. The skb's may be non-linear if the sctp * payload was fragmented on the way and ip had to reassemble them. * We add the rest of skb's to the first skb's fraglist. */struct sctp_ulpevent *sctp_make_reassembled_event(struct net *net, struct sk_buff_head *queue, struct sk_buff *f_frag, struct sk_buff *l_frag){ struct sk_buff *pos; struct sk_buff *new = NULL; struct sctp_ulpevent *event; struct sk_buff *pnext, *last; struct sk_buff *list = skb_shinfo(f_frag)->frag_list; /* Store the pointer to the 2nd skb */ if (f_frag == l_frag) pos = NULL; else pos = f_frag->next; /* Get the last skb in the f_frag's frag_list if present. */ for (last = list; list; last = list, list = list->next) ; /* Add the list of remaining fragments to the first fragments * frag_list. */ if (last) last->next = pos; else { if (skb_cloned(f_frag)) { /* This is a cloned skb, we can't just modify * the frag_list. We need a new skb to do that. * Instead of calling skb_unshare(), we'll do it * ourselves since we need to delay the free. */ new = skb_copy(f_frag, GFP_ATOMIC); if (!new) return NULL; /* try again later */ sctp_skb_set_owner_r(new, f_frag->sk); skb_shinfo(new)->frag_list = pos; } else skb_shinfo(f_frag)->frag_list = pos; } /* Remove the first fragment from the reassembly queue. */ __skb_unlink(f_frag, queue); /* if we did unshare, then free the old skb and re-assign */ if (new) { kfree_skb(f_frag); f_frag = new; } while (pos) { pnext = pos->next; /* Update the len and data_len fields of the first fragment. */ f_frag->len += pos->len; f_frag->data_len += pos->len; /* Remove the fragment from the reassembly queue. */ __skb_unlink(pos, queue); /* Break if we have reached the last fragment. */ if (pos == l_frag) break; pos->next = pnext; pos = pnext; } event = sctp_skb2event(f_frag); SCTP_INC_STATS(net, SCTP_MIB_REASMUSRMSGS); return event;} /* Helper function to check if an incoming chunk has filled up the last * missing fragment in a SCTP datagram and return the corresponding event. */static struct sctp_ulpevent *sctp_ulpq_retrieve_reassembled(struct sctp_ulpq *ulpq){ struct sk_buff *pos; struct sctp_ulpevent *cevent; struct sk_buff *first_frag = NULL; __u32 ctsn, next_tsn; struct sctp_ulpevent *retval = NULL; struct sk_buff *pd_first = NULL; struct sk_buff *pd_last = NULL; size_t pd_len = 0; struct sctp_association *asoc; u32 pd_point; /* Initialized to 0 just to avoid compiler warning message. Will * never be used with this value. It is referenced only after it * is set when we find the first fragment of a message. */ next_tsn = 0; /* The chunks are held in the reasm queue sorted by TSN. * Walk through the queue sequentially and look for a sequence of * fragmented chunks that complete a datagram. * 'first_frag' and next_tsn are reset when we find a chunk which * is the first fragment of a datagram. Once these 2 fields are set * we expect to find the remaining middle fragments and the last * fragment in order. If not, first_frag is reset to NULL and we * start the next pass when we find another first fragment. * * There is a potential to do partial delivery if user sets * SCTP_PARTIAL_DELIVERY_POINT option. Lets count some things here * to see if can do PD. */ skb_queue_walk(&ulpq->reasm, pos) { cevent = sctp_skb2event(pos); ctsn = cevent->tsn; switch (cevent->msg_flags & SCTP_DATA_FRAG_MASK) { case SCTP_DATA_FIRST_FRAG: /* If this "FIRST_FRAG" is the first * element in the queue, then count it towards * possible PD. */ if (skb_queue_is_first(&ulpq->reasm, pos)) { pd_first = pos; pd_last = pos; pd_len = pos->len; } else { pd_first = NULL; pd_last = NULL; pd_len = 0; } first_frag = pos; next_tsn = ctsn + 1; break; case SCTP_DATA_MIDDLE_FRAG: if ((first_frag) && (ctsn == next_tsn)) { next_tsn++; if (pd_first) { pd_last = pos; pd_len += pos->len; } } else first_frag = NULL; break; case SCTP_DATA_LAST_FRAG: if (first_frag && (ctsn == next_tsn)) goto found; else first_frag = NULL; break; } } asoc = ulpq->asoc; if (pd_first) { /* Make sure we can enter partial deliver. * We can trigger partial delivery only if framgent * interleave is set, or the socket is not already * in partial delivery. */ if (!sctp_sk(asoc->base.sk)->frag_interleave && atomic_read(&sctp_sk(asoc->base.sk)->pd_mode)) goto done; cevent = sctp_skb2event(pd_first); pd_point = sctp_sk(asoc->base.sk)->pd_point; if (pd_point && pd_point <= pd_len) { retval = sctp_make_reassembled_event(asoc->base.net, &ulpq->reasm, pd_first, pd_last); if (retval) sctp_ulpq_set_pd(ulpq); } }done: return retval;found: retval = sctp_make_reassembled_event(ulpq->asoc->base.net, &ulpq->reasm, first_frag, pos);Lines 1–500 of 1136. 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// 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. * Copyright (c) 2001 Nokia, Inc. * Copyright (c) 2001 La Monte H.P. Yarroll * * This abstraction carries sctp events to the ULP (sockets). * * 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> * La Monte H.P. Yarroll <piggy@acm.org> * Sridhar Samudrala <sri@us.ibm.com> */ #include <linux/slab.h> #include <linux/types.h> #include <linux/skbuff.h> #include <net/sock.h> #include <net/busy_poll.h> #include <net/sctp/structs.h> #include <net/sctp/sctp.h> #include <net/sctp/sm.h> /* Forward declarations for internal helpers. */ static struct sctp_ulpevent *sctp_ulpq_reasm(struct sctp_ulpq *ulpq, struct sctp_ulpevent *); static struct sctp_ulpevent *sctp_ulpq_order(struct sctp_ulpq *, struct sctp_ulpevent *); static void sctp_ulpq_reasm_drain(struct sctp_ulpq *ulpq); /* 1st Level Abstractions */ /* Initialize a ULP queue from a block of memory. */ struct sctp_ulpq *sctp_ulpq_init(struct sctp_ulpq *ulpq, struct sctp_association *asoc) { memset(ulpq, 0, sizeof(struct sctp_ulpq)); ulpq->asoc = asoc; skb_queue_head_init(&ulpq->reasm); skb_queue_head_init(&ulpq->reasm_uo); skb_queue_head_init(&ulpq->lobby); ulpq->pd_mode = 0; return ulpq; } /* Flush the reassembly and ordering queues. */ void sctp_ulpq_flush(struct sctp_ulpq *ulpq) { struct sk_buff *skb; struct sctp_ulpevent *event; while ((skb = __skb_dequeue(&ulpq->lobby)) != NULL) { event = sctp_skb2event(skb); sctp_ulpevent_free(event); } while ((skb = __skb_dequeue(&ulpq->reasm)) != NULL) { event = sctp_skb2event(skb); sctp_ulpevent_free(event); } while ((skb = __skb_dequeue(&ulpq->reasm_uo)) != NULL) { event = sctp_skb2event(skb); sctp_ulpevent_free(event); } } /* Dispose of a ulpqueue. */ void sctp_ulpq_free(struct sctp_ulpq *ulpq) { sctp_ulpq_flush(ulpq); } /* Process an incoming DATA chunk. */ int sctp_ulpq_tail_data(struct sctp_ulpq *ulpq, struct sctp_chunk *chunk, gfp_t gfp) { struct sk_buff_head temp; struct sctp_ulpevent *event; int event_eor = 0; /* Create an event from the incoming chunk. */ event = sctp_ulpevent_make_rcvmsg(chunk->asoc, chunk, gfp); if (!event) return -ENOMEM; event->ssn = ntohs(chunk->subh.data_hdr->ssn); event->ppid = chunk->subh.data_hdr->ppid; /* Do reassembly if needed. */ event = sctp_ulpq_reasm(ulpq, event); /* Do ordering if needed. */ if (event) { /* Create a temporary list to collect chunks on. */ skb_queue_head_init(&temp); __skb_queue_tail(&temp, sctp_event2skb(event)); if (event->msg_flags & MSG_EOR) event = sctp_ulpq_order(ulpq, event); } /* Send event to the ULP. 'event' is the sctp_ulpevent for * very first SKB on the 'temp' list. */ if (event) { event_eor = (event->msg_flags & MSG_EOR) ? 1 : 0; sctp_ulpq_tail_event(ulpq, &temp); } return event_eor; } /* Add a new event for propagation to the ULP. */ /* Clear the partial delivery mode for this socket. Note: This * assumes that no association is currently in partial delivery mode. */ int sctp_clear_pd(struct sock *sk, struct sctp_association *asoc) { struct sctp_sock *sp = sctp_sk(sk); if (atomic_dec_and_test(&sp->pd_mode)) { /* This means there are no other associations in PD, so * we can go ahead and clear out the lobby in one shot */ if (!skb_queue_empty(&sp->pd_lobby)) { skb_queue_splice_tail_init(&sp->pd_lobby, &sk->sk_receive_queue); return 1; } } else { /* There are other associations in PD, so we only need to * pull stuff out of the lobby that belongs to the * associations that is exiting PD (all of its notifications * are posted here). */ if (!skb_queue_empty(&sp->pd_lobby) && asoc) { struct sk_buff *skb, *tmp; struct sctp_ulpevent *event; sctp_skb_for_each(skb, &sp->pd_lobby, tmp) { event = sctp_skb2event(skb); if (event->asoc == asoc) { __skb_unlink(skb, &sp->pd_lobby); __skb_queue_tail(&sk->sk_receive_queue, skb); } } } } return 0; } /* Set the pd_mode on the socket and ulpq */ static void sctp_ulpq_set_pd(struct sctp_ulpq *ulpq) { struct sctp_sock *sp = sctp_sk(ulpq->asoc->base.sk); atomic_inc(&sp->pd_mode); ulpq->pd_mode = 1; } /* Clear the pd_mode and restart any pending messages waiting for delivery. */ static int sctp_ulpq_clear_pd(struct sctp_ulpq *ulpq) { ulpq->pd_mode = 0; sctp_ulpq_reasm_drain(ulpq); return sctp_clear_pd(ulpq->asoc->base.sk, ulpq->asoc); } int sctp_ulpq_tail_event(struct sctp_ulpq *ulpq, struct sk_buff_head *skb_list) { struct sock *sk = ulpq->asoc->base.sk; struct sctp_sock *sp = sctp_sk(sk); struct sctp_ulpevent *event; struct sk_buff_head *queue; struct sk_buff *skb; int clear_pd = 0; skb = __skb_peek(skb_list); event = sctp_skb2event(skb); /* If the socket is just going to throw this away, do not * even try to deliver it. */ if (sk->sk_shutdown & RCV_SHUTDOWN && (sk->sk_shutdown & SEND_SHUTDOWN || !sctp_ulpevent_is_notification(event))) goto out_free; if (!sctp_ulpevent_is_notification(event)) { sk_mark_napi_id(sk, skb); sk_incoming_cpu_update(sk); } /* Check if the user wishes to receive this event. */ if (!sctp_ulpevent_is_enabled(event, ulpq->asoc->subscribe)) goto out_free; /* If we are in partial delivery mode, post to the lobby until * partial delivery is cleared, unless, of course _this_ is * the association the cause of the partial delivery. */ if (atomic_read(&sp->pd_mode) == 0) { queue = &sk->sk_receive_queue; } else { if (ulpq->pd_mode) { /* If the association is in partial delivery, we * need to finish delivering the partially processed * packet before passing any other data. This is * because we don't truly support stream interleaving. */ if ((event->msg_flags & MSG_NOTIFICATION) || (SCTP_DATA_NOT_FRAG == (event->msg_flags & SCTP_DATA_FRAG_MASK))) queue = &sp->pd_lobby; else { clear_pd = event->msg_flags & MSG_EOR; queue = &sk->sk_receive_queue; } } else { /* * If fragment interleave is enabled, we * can queue this to the receive queue instead * of the lobby. */ if (sp->frag_interleave) queue = &sk->sk_receive_queue; else queue = &sp->pd_lobby; } } skb_queue_splice_tail_init(skb_list, queue); /* Did we just complete partial delivery and need to get * rolling again? Move pending data to the receive * queue. */ if (clear_pd) sctp_ulpq_clear_pd(ulpq); if (queue == &sk->sk_receive_queue && !sp->data_ready_signalled) { if (!sock_owned_by_user(sk)) sp->data_ready_signalled = 1; sk->sk_data_ready(sk); } return 1; out_free: if (skb_list) sctp_queue_purge_ulpevents(skb_list); else sctp_ulpevent_free(event); return 0; } /* 2nd Level Abstractions */ /* Helper function to store chunks that need to be reassembled. */ static void sctp_ulpq_store_reasm(struct sctp_ulpq *ulpq, struct sctp_ulpevent *event) { struct sk_buff *pos; struct sctp_ulpevent *cevent; __u32 tsn, ctsn; tsn = event->tsn; /* See if it belongs at the end. */ pos = skb_peek_tail(&ulpq->reasm); if (!pos) { __skb_queue_tail(&ulpq->reasm, sctp_event2skb(event)); return; } /* Short circuit just dropping it at the end. */ cevent = sctp_skb2event(pos); ctsn = cevent->tsn; if (TSN_lt(ctsn, tsn)) { __skb_queue_tail(&ulpq->reasm, sctp_event2skb(event)); return; } /* Find the right place in this list. We store them by TSN. */ skb_queue_walk(&ulpq->reasm, pos) { cevent = sctp_skb2event(pos); ctsn = cevent->tsn; if (TSN_lt(tsn, ctsn)) break; } /* Insert before pos. */ __skb_queue_before(&ulpq->reasm, pos, sctp_event2skb(event)); } /* Helper function to return an event corresponding to the reassembled * datagram. * This routine creates a re-assembled skb given the first and last skb's * as stored in the reassembly queue. The skb's may be non-linear if the sctp * payload was fragmented on the way and ip had to reassemble them. * We add the rest of skb's to the first skb's fraglist. */ struct sctp_ulpevent *sctp_make_reassembled_event(struct net *net, struct sk_buff_head *queue, struct sk_buff *f_frag, struct sk_buff *l_frag) { struct sk_buff *pos; struct sk_buff *new = NULL; struct sctp_ulpevent *event; struct sk_buff *pnext, *last; struct sk_buff *list = skb_shinfo(f_frag)->frag_list; /* Store the pointer to the 2nd skb */ if (f_frag == l_frag) pos = NULL; else pos = f_frag->next; /* Get the last skb in the f_frag's frag_list if present. */ for (last = list; list; last = list, list = list->next) ; /* Add the list of remaining fragments to the first fragments * frag_list. */ if (last) last->next = pos; else { if (skb_cloned(f_frag)) { /* This is a cloned skb, we can't just modify * the frag_list. We need a new skb to do that. * Instead of calling skb_unshare(), we'll do it * ourselves since we need to delay the free. */ new = skb_copy(f_frag, GFP_ATOMIC); if (!new) return NULL; /* try again later */ sctp_skb_set_owner_r(new, f_frag->sk); skb_shinfo(new)->frag_list = pos; } else skb_shinfo(f_frag)->frag_list = pos; } /* Remove the first fragment from the reassembly queue. */ __skb_unlink(f_frag, queue); /* if we did unshare, then free the old skb and re-assign */ if (new) { kfree_skb(f_frag); f_frag = new; } while (pos) { pnext = pos->next; /* Update the len and data_len fields of the first fragment. */ f_frag->len += pos->len; f_frag->data_len += pos->len; /* Remove the fragment from the reassembly queue. */ __skb_unlink(pos, queue); /* Break if we have reached the last fragment. */ if (pos == l_frag) break; pos->next = pnext; pos = pnext; } event = sctp_skb2event(f_frag); SCTP_INC_STATS(net, SCTP_MIB_REASMUSRMSGS); return event; } /* Helper function to check if an incoming chunk has filled up the last * missing fragment in a SCTP datagram and return the corresponding event. */ static struct sctp_ulpevent *sctp_ulpq_retrieve_reassembled(struct sctp_ulpq *ulpq) { struct sk_buff *pos; struct sctp_ulpevent *cevent; struct sk_buff *first_frag = NULL; __u32 ctsn, next_tsn; struct sctp_ulpevent *retval = NULL; struct sk_buff *pd_first = NULL; struct sk_buff *pd_last = NULL; size_t pd_len = 0; struct sctp_association *asoc; u32 pd_point; /* Initialized to 0 just to avoid compiler warning message. Will * never be used with this value. It is referenced only after it * is set when we find the first fragment of a message. */ next_tsn = 0; /* The chunks are held in the reasm queue sorted by TSN. * Walk through the queue sequentially and look for a sequence of * fragmented chunks that complete a datagram. * 'first_frag' and next_tsn are reset when we find a chunk which * is the first fragment of a datagram. Once these 2 fields are set * we expect to find the remaining middle fragments and the last * fragment in order. If not, first_frag is reset to NULL and we * start the next pass when we find another first fragment. * * There is a potential to do partial delivery if user sets * SCTP_PARTIAL_DELIVERY_POINT option. Lets count some things here * to see if can do PD. */ skb_queue_walk(&ulpq->reasm, pos) { cevent = sctp_skb2event(pos); ctsn = cevent->tsn; switch (cevent->msg_flags & SCTP_DATA_FRAG_MASK) { case SCTP_DATA_FIRST_FRAG: /* If this "FIRST_FRAG" is the first * element in the queue, then count it towards * possible PD. */ if (skb_queue_is_first(&ulpq->reasm, pos)) { pd_first = pos; pd_last = pos; pd_len = pos->len; } else { pd_first = NULL; pd_last = NULL; pd_len = 0; } first_frag = pos; next_tsn = ctsn + 1; break; case SCTP_DATA_MIDDLE_FRAG: if ((first_frag) && (ctsn == next_tsn)) { next_tsn++; if (pd_first) { pd_last = pos; pd_len += pos->len; } } else first_frag = NULL; break; case SCTP_DATA_LAST_FRAG: if (first_frag && (ctsn == next_tsn)) goto found; else first_frag = NULL; break; } } asoc = ulpq->asoc; if (pd_first) { /* Make sure we can enter partial deliver. * We can trigger partial delivery only if framgent * interleave is set, or the socket is not already * in partial delivery. */ if (!sctp_sk(asoc->base.sk)->frag_interleave && atomic_read(&sctp_sk(asoc->base.sk)->pd_mode)) goto done; cevent = sctp_skb2event(pd_first); pd_point = sctp_sk(asoc->base.sk)->pd_point; if (pd_point && pd_point <= pd_len) { retval = sctp_make_reassembled_event(asoc->base.net, &ulpq->reasm, pd_first, pd_last); if (retval) sctp_ulpq_set_pd(ulpq); } } done: return retval; found: retval = sctp_make_reassembled_event(ulpq->asoc->base.net, &ulpq->reasm, first_frag, pos);