kernel-ark/net/sctp/input.c

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/* SCTP kernel implementation
* Copyright (c) 1999-2000 Cisco, Inc.
* Copyright (c) 1999-2001 Motorola, Inc.
* Copyright (c) 2001-2003 International Business Machines, Corp.
* Copyright (c) 2001 Intel Corp.
* Copyright (c) 2001 Nokia, Inc.
* Copyright (c) 2001 La Monte H.P. Yarroll
*
* This file is part of the SCTP kernel implementation
*
* These functions handle all input from the IP layer into SCTP.
*
* This SCTP implementation is free software;
* you can redistribute it and/or modify it under the terms of
* the GNU General Public License as published by
* the Free Software Foundation; either version 2, or (at your option)
* any later version.
*
* This SCTP implementation is distributed in the hope that it
* will be useful, but WITHOUT ANY WARRANTY; without even the implied
* ************************
* warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
* See the GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with GNU CC; see the file COPYING. If not, write to
* the Free Software Foundation, 59 Temple Place - Suite 330,
* Boston, MA 02111-1307, USA.
*
* Please send any bug reports or fixes you make to the
* email address(es):
* lksctp developers <lksctp-developers@lists.sourceforge.net>
*
* Or submit a bug report through the following website:
* http://www.sf.net/projects/lksctp
*
* Written or modified by:
* La Monte H.P. Yarroll <piggy@acm.org>
* Karl Knutson <karl@athena.chicago.il.us>
* Xingang Guo <xingang.guo@intel.com>
* Jon Grimm <jgrimm@us.ibm.com>
* Hui Huang <hui.huang@nokia.com>
* Daisy Chang <daisyc@us.ibm.com>
* Sridhar Samudrala <sri@us.ibm.com>
* Ardelle Fan <ardelle.fan@intel.com>
*
* Any bugs reported given to us we will try to fix... any fixes shared will
* be incorporated into the next SCTP release.
*/
#include <linux/types.h>
#include <linux/list.h> /* For struct list_head */
#include <linux/socket.h>
#include <linux/ip.h>
#include <linux/time.h> /* For struct timeval */
include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h percpu.h is included by sched.h and module.h and thus ends up being included when building most .c files. percpu.h includes slab.h which in turn includes gfp.h making everything defined by the two files universally available and complicating inclusion dependencies. percpu.h -> slab.h dependency is about to be removed. Prepare for this change by updating users of gfp and slab facilities include those headers directly instead of assuming availability. As this conversion needs to touch large number of source files, the following script is used as the basis of conversion. http://userweb.kernel.org/~tj/misc/slabh-sweep.py The script does the followings. * Scan files for gfp and slab usages and update includes such that only the necessary includes are there. ie. if only gfp is used, gfp.h, if slab is used, slab.h. * When the script inserts a new include, it looks at the include blocks and try to put the new include such that its order conforms to its surrounding. It's put in the include block which contains core kernel includes, in the same order that the rest are ordered - alphabetical, Christmas tree, rev-Xmas-tree or at the end if there doesn't seem to be any matching order. * If the script can't find a place to put a new include (mostly because the file doesn't have fitting include block), it prints out an error message indicating which .h file needs to be added to the file. The conversion was done in the following steps. 1. The initial automatic conversion of all .c files updated slightly over 4000 files, deleting around 700 includes and adding ~480 gfp.h and ~3000 slab.h inclusions. The script emitted errors for ~400 files. 2. Each error was manually checked. Some didn't need the inclusion, some needed manual addition while adding it to implementation .h or embedding .c file was more appropriate for others. This step added inclusions to around 150 files. 3. The script was run again and the output was compared to the edits from #2 to make sure no file was left behind. 4. Several build tests were done and a couple of problems were fixed. e.g. lib/decompress_*.c used malloc/free() wrappers around slab APIs requiring slab.h to be added manually. 5. The script was run on all .h files but without automatically editing them as sprinkling gfp.h and slab.h inclusions around .h files could easily lead to inclusion dependency hell. Most gfp.h inclusion directives were ignored as stuff from gfp.h was usually wildly available and often used in preprocessor macros. Each slab.h inclusion directive was examined and added manually as necessary. 6. percpu.h was updated not to include slab.h. 7. Build test were done on the following configurations and failures were fixed. CONFIG_GCOV_KERNEL was turned off for all tests (as my distributed build env didn't work with gcov compiles) and a few more options had to be turned off depending on archs to make things build (like ipr on powerpc/64 which failed due to missing writeq). * x86 and x86_64 UP and SMP allmodconfig and a custom test config. * powerpc and powerpc64 SMP allmodconfig * sparc and sparc64 SMP allmodconfig * ia64 SMP allmodconfig * s390 SMP allmodconfig * alpha SMP allmodconfig * um on x86_64 SMP allmodconfig 8. percpu.h modifications were reverted so that it could be applied as a separate patch and serve as bisection point. Given the fact that I had only a couple of failures from tests on step 6, I'm fairly confident about the coverage of this conversion patch. If there is a breakage, it's likely to be something in one of the arch headers which should be easily discoverable easily on most builds of the specific arch. Signed-off-by: Tejun Heo <tj@kernel.org> Guess-its-ok-by: Christoph Lameter <cl@linux-foundation.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
2010-03-24 08:04:11 +00:00
#include <linux/slab.h>
#include <net/ip.h>
#include <net/icmp.h>
#include <net/snmp.h>
#include <net/sock.h>
#include <net/xfrm.h>
#include <net/sctp/sctp.h>
#include <net/sctp/sm.h>
#include <net/sctp/checksum.h>
#include <net/net_namespace.h>
/* Forward declarations for internal helpers. */
static int sctp_rcv_ootb(struct sk_buff *);
static struct sctp_association *__sctp_rcv_lookup(struct sk_buff *skb,
const union sctp_addr *laddr,
const union sctp_addr *paddr,
struct sctp_transport **transportp);
static struct sctp_endpoint *__sctp_rcv_lookup_endpoint(const union sctp_addr *laddr);
static struct sctp_association *__sctp_lookup_association(
const union sctp_addr *local,
const union sctp_addr *peer,
struct sctp_transport **pt);
static int sctp_add_backlog(struct sock *sk, struct sk_buff *skb);
[SCTP]: A better solution to fix the race between sctp_peeloff() and sctp_rcv(). The goal is to hold the ref on the association/endpoint throughout the state-machine process. We accomplish like this: /* ref on the assoc/ep is taken during lookup */ if owned_by_user(sk) sctp_add_backlog(skb, sk); else inqueue_push(skb, sk); /* drop the ref on the assoc/ep */ However, in sctp_add_backlog() we take the ref on assoc/ep and hold it while the skb is on the backlog queue. This allows us to get rid of the sock_hold/sock_put in the lookup routines. Now sctp_backlog_rcv() needs to account for potential association move. In the unlikely event that association moved, we need to retest if the new socket is locked by user. If we don't this, we may have two packets racing up the stack toward the same socket and we can't deal with it. If the new socket is still locked, we'll just add the skb to its backlog continuing to hold the ref on the association. This get's rid of the need to move packets from one backlog to another and it also safe in case new packets arrive on the same backlog queue. The last step, is to lock the new socket when we are moving the association to it. This is needed in case any new packets arrive on the association when it moved. We want these to go to the backlog since we would like to avoid the race between this new packet and a packet that may be sitting on the backlog queue of the old socket toward the same association. Signed-off-by: Vladislav Yasevich <vladislav.yasevich@hp.com> Signed-off-by: Sridhar Samudrala <sri@us.ibm.com>
2006-05-19 18:01:18 +00:00
/* Calculate the SCTP checksum of an SCTP packet. */
static inline int sctp_rcv_checksum(struct sk_buff *skb)
{
struct sctphdr *sh = sctp_hdr(skb);
__le32 cmp = sh->checksum;
struct sk_buff *list;
__le32 val;
__u32 tmp = sctp_start_cksum((__u8 *)sh, skb_headlen(skb));
skb_walk_frags(skb, list)
tmp = sctp_update_cksum((__u8 *)list->data, skb_headlen(list),
tmp);
val = sctp_end_cksum(tmp);
if (val != cmp) {
/* CRC failure, dump it. */
SCTP_INC_STATS_BH(SCTP_MIB_CHECKSUMERRORS);
return -1;
}
return 0;
}
struct sctp_input_cb {
union {
struct inet_skb_parm h4;
#if IS_ENABLED(CONFIG_IPV6)
struct inet6_skb_parm h6;
#endif
} header;
struct sctp_chunk *chunk;
};
#define SCTP_INPUT_CB(__skb) ((struct sctp_input_cb *)&((__skb)->cb[0]))
/*
* This is the routine which IP calls when receiving an SCTP packet.
*/
int sctp_rcv(struct sk_buff *skb)
{
struct sock *sk;
struct sctp_association *asoc;
struct sctp_endpoint *ep = NULL;
struct sctp_ep_common *rcvr;
struct sctp_transport *transport = NULL;
struct sctp_chunk *chunk;
struct sctphdr *sh;
union sctp_addr src;
union sctp_addr dest;
int family;
struct sctp_af *af;
if (skb->pkt_type!=PACKET_HOST)
goto discard_it;
SCTP_INC_STATS_BH(SCTP_MIB_INSCTPPACKS);
if (skb_linearize(skb))
goto discard_it;
sh = sctp_hdr(skb);
/* Pull up the IP and SCTP headers. */
__skb_pull(skb, skb_transport_offset(skb));
if (skb->len < sizeof(struct sctphdr))
goto discard_it;
if (!sctp_checksum_disable && !skb_csum_unnecessary(skb) &&
sctp_rcv_checksum(skb) < 0)
goto discard_it;
skb_pull(skb, sizeof(struct sctphdr));
/* Make sure we at least have chunk headers worth of data left. */
if (skb->len < sizeof(struct sctp_chunkhdr))
goto discard_it;
family = ipver2af(ip_hdr(skb)->version);
af = sctp_get_af_specific(family);
if (unlikely(!af))
goto discard_it;
/* Initialize local addresses for lookups. */
af->from_skb(&src, skb, 1);
af->from_skb(&dest, skb, 0);
/* If the packet is to or from a non-unicast address,
* silently discard the packet.
*
* This is not clearly defined in the RFC except in section
* 8.4 - OOTB handling. However, based on the book "Stream Control
* Transmission Protocol" 2.1, "It is important to note that the
* IP address of an SCTP transport address must be a routable
* unicast address. In other words, IP multicast addresses and
* IP broadcast addresses cannot be used in an SCTP transport
* address."
*/
if (!af->addr_valid(&src, NULL, skb) ||
!af->addr_valid(&dest, NULL, skb))
goto discard_it;
asoc = __sctp_rcv_lookup(skb, &src, &dest, &transport);
if (!asoc)
ep = __sctp_rcv_lookup_endpoint(&dest);
/* Retrieve the common input handling substructure. */
rcvr = asoc ? &asoc->base : &ep->base;
sk = rcvr->sk;
/*
* If a frame arrives on an interface and the receiving socket is
* bound to another interface, via SO_BINDTODEVICE, treat it as OOTB
*/
if (sk->sk_bound_dev_if && (sk->sk_bound_dev_if != af->skb_iif(skb)))
{
if (asoc) {
sctp_association_put(asoc);
asoc = NULL;
} else {
sctp_endpoint_put(ep);
ep = NULL;
}
sk = sctp_get_ctl_sock();
ep = sctp_sk(sk)->ep;
sctp_endpoint_hold(ep);
rcvr = &ep->base;
}
/*
* RFC 2960, 8.4 - Handle "Out of the blue" Packets.
* An SCTP packet is called an "out of the blue" (OOTB)
* packet if it is correctly formed, i.e., passed the
* receiver's checksum check, but the receiver is not
* able to identify the association to which this
* packet belongs.
*/
if (!asoc) {
if (sctp_rcv_ootb(skb)) {
SCTP_INC_STATS_BH(SCTP_MIB_OUTOFBLUES);
goto discard_release;
}
}
if (!xfrm_policy_check(sk, XFRM_POLICY_IN, skb, family))
goto discard_release;
nf_reset(skb);
if (sk_filter(sk, skb))
goto discard_release;
/* Create an SCTP packet structure. */
chunk = sctp_chunkify(skb, asoc, sk);
if (!chunk)
goto discard_release;
SCTP_INPUT_CB(skb)->chunk = chunk;
/* Remember what endpoint is to handle this packet. */
chunk->rcvr = rcvr;
/* Remember the SCTP header. */
chunk->sctp_hdr = sh;
/* Set the source and destination addresses of the incoming chunk. */
sctp_init_addrs(chunk, &src, &dest);
/* Remember where we came from. */
chunk->transport = transport;
/* Acquire access to the sock lock. Note: We are safe from other
* bottom halves on this lock, but a user may be in the lock too,
* so check if it is busy.
*/
sctp_bh_lock_sock(sk);
if (sk != rcvr->sk) {
/* Our cached sk is different from the rcvr->sk. This is
* because migrate()/accept() may have moved the association
* to a new socket and released all the sockets. So now we
* are holding a lock on the old socket while the user may
* be doing something with the new socket. Switch our veiw
* of the current sk.
*/
sctp_bh_unlock_sock(sk);
sk = rcvr->sk;
sctp_bh_lock_sock(sk);
}
if (sock_owned_by_user(sk)) {
if (sctp_add_backlog(sk, skb)) {
sctp_bh_unlock_sock(sk);
sctp_chunk_free(chunk);
skb = NULL; /* sctp_chunk_free already freed the skb */
goto discard_release;
}
SCTP_INC_STATS_BH(SCTP_MIB_IN_PKT_BACKLOG);
} else {
SCTP_INC_STATS_BH(SCTP_MIB_IN_PKT_SOFTIRQ);
[SCTP]: A better solution to fix the race between sctp_peeloff() and sctp_rcv(). The goal is to hold the ref on the association/endpoint throughout the state-machine process. We accomplish like this: /* ref on the assoc/ep is taken during lookup */ if owned_by_user(sk) sctp_add_backlog(skb, sk); else inqueue_push(skb, sk); /* drop the ref on the assoc/ep */ However, in sctp_add_backlog() we take the ref on assoc/ep and hold it while the skb is on the backlog queue. This allows us to get rid of the sock_hold/sock_put in the lookup routines. Now sctp_backlog_rcv() needs to account for potential association move. In the unlikely event that association moved, we need to retest if the new socket is locked by user. If we don't this, we may have two packets racing up the stack toward the same socket and we can't deal with it. If the new socket is still locked, we'll just add the skb to its backlog continuing to hold the ref on the association. This get's rid of the need to move packets from one backlog to another and it also safe in case new packets arrive on the same backlog queue. The last step, is to lock the new socket when we are moving the association to it. This is needed in case any new packets arrive on the association when it moved. We want these to go to the backlog since we would like to avoid the race between this new packet and a packet that may be sitting on the backlog queue of the old socket toward the same association. Signed-off-by: Vladislav Yasevich <vladislav.yasevich@hp.com> Signed-off-by: Sridhar Samudrala <sri@us.ibm.com>
2006-05-19 18:01:18 +00:00
sctp_inq_push(&chunk->rcvr->inqueue, chunk);
}
sctp_bh_unlock_sock(sk);
[SCTP]: A better solution to fix the race between sctp_peeloff() and sctp_rcv(). The goal is to hold the ref on the association/endpoint throughout the state-machine process. We accomplish like this: /* ref on the assoc/ep is taken during lookup */ if owned_by_user(sk) sctp_add_backlog(skb, sk); else inqueue_push(skb, sk); /* drop the ref on the assoc/ep */ However, in sctp_add_backlog() we take the ref on assoc/ep and hold it while the skb is on the backlog queue. This allows us to get rid of the sock_hold/sock_put in the lookup routines. Now sctp_backlog_rcv() needs to account for potential association move. In the unlikely event that association moved, we need to retest if the new socket is locked by user. If we don't this, we may have two packets racing up the stack toward the same socket and we can't deal with it. If the new socket is still locked, we'll just add the skb to its backlog continuing to hold the ref on the association. This get's rid of the need to move packets from one backlog to another and it also safe in case new packets arrive on the same backlog queue. The last step, is to lock the new socket when we are moving the association to it. This is needed in case any new packets arrive on the association when it moved. We want these to go to the backlog since we would like to avoid the race between this new packet and a packet that may be sitting on the backlog queue of the old socket toward the same association. Signed-off-by: Vladislav Yasevich <vladislav.yasevich@hp.com> Signed-off-by: Sridhar Samudrala <sri@us.ibm.com>
2006-05-19 18:01:18 +00:00
/* Release the asoc/ep ref we took in the lookup calls. */
if (asoc)
sctp_association_put(asoc);
else
sctp_endpoint_put(ep);
return 0;
discard_it:
SCTP_INC_STATS_BH(SCTP_MIB_IN_PKT_DISCARDS);
kfree_skb(skb);
return 0;
discard_release:
[SCTP]: A better solution to fix the race between sctp_peeloff() and sctp_rcv(). The goal is to hold the ref on the association/endpoint throughout the state-machine process. We accomplish like this: /* ref on the assoc/ep is taken during lookup */ if owned_by_user(sk) sctp_add_backlog(skb, sk); else inqueue_push(skb, sk); /* drop the ref on the assoc/ep */ However, in sctp_add_backlog() we take the ref on assoc/ep and hold it while the skb is on the backlog queue. This allows us to get rid of the sock_hold/sock_put in the lookup routines. Now sctp_backlog_rcv() needs to account for potential association move. In the unlikely event that association moved, we need to retest if the new socket is locked by user. If we don't this, we may have two packets racing up the stack toward the same socket and we can't deal with it. If the new socket is still locked, we'll just add the skb to its backlog continuing to hold the ref on the association. This get's rid of the need to move packets from one backlog to another and it also safe in case new packets arrive on the same backlog queue. The last step, is to lock the new socket when we are moving the association to it. This is needed in case any new packets arrive on the association when it moved. We want these to go to the backlog since we would like to avoid the race between this new packet and a packet that may be sitting on the backlog queue of the old socket toward the same association. Signed-off-by: Vladislav Yasevich <vladislav.yasevich@hp.com> Signed-off-by: Sridhar Samudrala <sri@us.ibm.com>
2006-05-19 18:01:18 +00:00
/* Release the asoc/ep ref we took in the lookup calls. */
if (asoc)
sctp_association_put(asoc);
else
sctp_endpoint_put(ep);
goto discard_it;
}
[SCTP]: A better solution to fix the race between sctp_peeloff() and sctp_rcv(). The goal is to hold the ref on the association/endpoint throughout the state-machine process. We accomplish like this: /* ref on the assoc/ep is taken during lookup */ if owned_by_user(sk) sctp_add_backlog(skb, sk); else inqueue_push(skb, sk); /* drop the ref on the assoc/ep */ However, in sctp_add_backlog() we take the ref on assoc/ep and hold it while the skb is on the backlog queue. This allows us to get rid of the sock_hold/sock_put in the lookup routines. Now sctp_backlog_rcv() needs to account for potential association move. In the unlikely event that association moved, we need to retest if the new socket is locked by user. If we don't this, we may have two packets racing up the stack toward the same socket and we can't deal with it. If the new socket is still locked, we'll just add the skb to its backlog continuing to hold the ref on the association. This get's rid of the need to move packets from one backlog to another and it also safe in case new packets arrive on the same backlog queue. The last step, is to lock the new socket when we are moving the association to it. This is needed in case any new packets arrive on the association when it moved. We want these to go to the backlog since we would like to avoid the race between this new packet and a packet that may be sitting on the backlog queue of the old socket toward the same association. Signed-off-by: Vladislav Yasevich <vladislav.yasevich@hp.com> Signed-off-by: Sridhar Samudrala <sri@us.ibm.com>
2006-05-19 18:01:18 +00:00
/* Process the backlog queue of the socket. Every skb on
* the backlog holds a ref on an association or endpoint.
* We hold this ref throughout the state machine to make
* sure that the structure we need is still around.
*/
int sctp_backlog_rcv(struct sock *sk, struct sk_buff *skb)
{
struct sctp_chunk *chunk = SCTP_INPUT_CB(skb)->chunk;
struct sctp_inq *inqueue = &chunk->rcvr->inqueue;
struct sctp_ep_common *rcvr = NULL;
[SCTP]: A better solution to fix the race between sctp_peeloff() and sctp_rcv(). The goal is to hold the ref on the association/endpoint throughout the state-machine process. We accomplish like this: /* ref on the assoc/ep is taken during lookup */ if owned_by_user(sk) sctp_add_backlog(skb, sk); else inqueue_push(skb, sk); /* drop the ref on the assoc/ep */ However, in sctp_add_backlog() we take the ref on assoc/ep and hold it while the skb is on the backlog queue. This allows us to get rid of the sock_hold/sock_put in the lookup routines. Now sctp_backlog_rcv() needs to account for potential association move. In the unlikely event that association moved, we need to retest if the new socket is locked by user. If we don't this, we may have two packets racing up the stack toward the same socket and we can't deal with it. If the new socket is still locked, we'll just add the skb to its backlog continuing to hold the ref on the association. This get's rid of the need to move packets from one backlog to another and it also safe in case new packets arrive on the same backlog queue. The last step, is to lock the new socket when we are moving the association to it. This is needed in case any new packets arrive on the association when it moved. We want these to go to the backlog since we would like to avoid the race between this new packet and a packet that may be sitting on the backlog queue of the old socket toward the same association. Signed-off-by: Vladislav Yasevich <vladislav.yasevich@hp.com> Signed-off-by: Sridhar Samudrala <sri@us.ibm.com>
2006-05-19 18:01:18 +00:00
int backloged = 0;
rcvr = chunk->rcvr;
[SCTP]: A better solution to fix the race between sctp_peeloff() and sctp_rcv(). The goal is to hold the ref on the association/endpoint throughout the state-machine process. We accomplish like this: /* ref on the assoc/ep is taken during lookup */ if owned_by_user(sk) sctp_add_backlog(skb, sk); else inqueue_push(skb, sk); /* drop the ref on the assoc/ep */ However, in sctp_add_backlog() we take the ref on assoc/ep and hold it while the skb is on the backlog queue. This allows us to get rid of the sock_hold/sock_put in the lookup routines. Now sctp_backlog_rcv() needs to account for potential association move. In the unlikely event that association moved, we need to retest if the new socket is locked by user. If we don't this, we may have two packets racing up the stack toward the same socket and we can't deal with it. If the new socket is still locked, we'll just add the skb to its backlog continuing to hold the ref on the association. This get's rid of the need to move packets from one backlog to another and it also safe in case new packets arrive on the same backlog queue. The last step, is to lock the new socket when we are moving the association to it. This is needed in case any new packets arrive on the association when it moved. We want these to go to the backlog since we would like to avoid the race between this new packet and a packet that may be sitting on the backlog queue of the old socket toward the same association. Signed-off-by: Vladislav Yasevich <vladislav.yasevich@hp.com> Signed-off-by: Sridhar Samudrala <sri@us.ibm.com>
2006-05-19 18:01:18 +00:00
/* If the rcvr is dead then the association or endpoint
* has been deleted and we can safely drop the chunk
* and refs that we are holding.
*/
if (rcvr->dead) {
sctp_chunk_free(chunk);
goto done;
}
if (unlikely(rcvr->sk != sk)) {
/* In this case, the association moved from one socket to
* another. We are currently sitting on the backlog of the
* old socket, so we need to move.
* However, since we are here in the process context we
* need to take make sure that the user doesn't own
* the new socket when we process the packet.
* If the new socket is user-owned, queue the chunk to the
* backlog of the new socket without dropping any refs.
* Otherwise, we can safely push the chunk on the inqueue.
*/
sk = rcvr->sk;
sctp_bh_lock_sock(sk);
if (sock_owned_by_user(sk)) {
if (sk_add_backlog(sk, skb, sk->sk_rcvbuf))
sctp_chunk_free(chunk);
else
backloged = 1;
[SCTP]: A better solution to fix the race between sctp_peeloff() and sctp_rcv(). The goal is to hold the ref on the association/endpoint throughout the state-machine process. We accomplish like this: /* ref on the assoc/ep is taken during lookup */ if owned_by_user(sk) sctp_add_backlog(skb, sk); else inqueue_push(skb, sk); /* drop the ref on the assoc/ep */ However, in sctp_add_backlog() we take the ref on assoc/ep and hold it while the skb is on the backlog queue. This allows us to get rid of the sock_hold/sock_put in the lookup routines. Now sctp_backlog_rcv() needs to account for potential association move. In the unlikely event that association moved, we need to retest if the new socket is locked by user. If we don't this, we may have two packets racing up the stack toward the same socket and we can't deal with it. If the new socket is still locked, we'll just add the skb to its backlog continuing to hold the ref on the association. This get's rid of the need to move packets from one backlog to another and it also safe in case new packets arrive on the same backlog queue. The last step, is to lock the new socket when we are moving the association to it. This is needed in case any new packets arrive on the association when it moved. We want these to go to the backlog since we would like to avoid the race between this new packet and a packet that may be sitting on the backlog queue of the old socket toward the same association. Signed-off-by: Vladislav Yasevich <vladislav.yasevich@hp.com> Signed-off-by: Sridhar Samudrala <sri@us.ibm.com>
2006-05-19 18:01:18 +00:00
} else
sctp_inq_push(inqueue, chunk);
sctp_bh_unlock_sock(sk);
/* If the chunk was backloged again, don't drop refs */
if (backloged)
return 0;
} else {
sctp_inq_push(inqueue, chunk);
}
done:
/* Release the refs we took in sctp_add_backlog */
if (SCTP_EP_TYPE_ASSOCIATION == rcvr->type)
sctp_association_put(sctp_assoc(rcvr));
else if (SCTP_EP_TYPE_SOCKET == rcvr->type)
sctp_endpoint_put(sctp_ep(rcvr));
else
BUG();
return 0;
}
static int sctp_add_backlog(struct sock *sk, struct sk_buff *skb)
{
[SCTP]: A better solution to fix the race between sctp_peeloff() and sctp_rcv(). The goal is to hold the ref on the association/endpoint throughout the state-machine process. We accomplish like this: /* ref on the assoc/ep is taken during lookup */ if owned_by_user(sk) sctp_add_backlog(skb, sk); else inqueue_push(skb, sk); /* drop the ref on the assoc/ep */ However, in sctp_add_backlog() we take the ref on assoc/ep and hold it while the skb is on the backlog queue. This allows us to get rid of the sock_hold/sock_put in the lookup routines. Now sctp_backlog_rcv() needs to account for potential association move. In the unlikely event that association moved, we need to retest if the new socket is locked by user. If we don't this, we may have two packets racing up the stack toward the same socket and we can't deal with it. If the new socket is still locked, we'll just add the skb to its backlog continuing to hold the ref on the association. This get's rid of the need to move packets from one backlog to another and it also safe in case new packets arrive on the same backlog queue. The last step, is to lock the new socket when we are moving the association to it. This is needed in case any new packets arrive on the association when it moved. We want these to go to the backlog since we would like to avoid the race between this new packet and a packet that may be sitting on the backlog queue of the old socket toward the same association. Signed-off-by: Vladislav Yasevich <vladislav.yasevich@hp.com> Signed-off-by: Sridhar Samudrala <sri@us.ibm.com>
2006-05-19 18:01:18 +00:00
struct sctp_chunk *chunk = SCTP_INPUT_CB(skb)->chunk;
struct sctp_ep_common *rcvr = chunk->rcvr;
int ret;
ret = sk_add_backlog(sk, skb, sk->sk_rcvbuf);
if (!ret) {
/* Hold the assoc/ep while hanging on the backlog queue.
* This way, we know structures we need will not disappear
* from us
*/
if (SCTP_EP_TYPE_ASSOCIATION == rcvr->type)
sctp_association_hold(sctp_assoc(rcvr));
else if (SCTP_EP_TYPE_SOCKET == rcvr->type)
sctp_endpoint_hold(sctp_ep(rcvr));
else
BUG();
}
return ret;
[SCTP]: A better solution to fix the race between sctp_peeloff() and sctp_rcv(). The goal is to hold the ref on the association/endpoint throughout the state-machine process. We accomplish like this: /* ref on the assoc/ep is taken during lookup */ if owned_by_user(sk) sctp_add_backlog(skb, sk); else inqueue_push(skb, sk); /* drop the ref on the assoc/ep */ However, in sctp_add_backlog() we take the ref on assoc/ep and hold it while the skb is on the backlog queue. This allows us to get rid of the sock_hold/sock_put in the lookup routines. Now sctp_backlog_rcv() needs to account for potential association move. In the unlikely event that association moved, we need to retest if the new socket is locked by user. If we don't this, we may have two packets racing up the stack toward the same socket and we can't deal with it. If the new socket is still locked, we'll just add the skb to its backlog continuing to hold the ref on the association. This get's rid of the need to move packets from one backlog to another and it also safe in case new packets arrive on the same backlog queue. The last step, is to lock the new socket when we are moving the association to it. This is needed in case any new packets arrive on the association when it moved. We want these to go to the backlog since we would like to avoid the race between this new packet and a packet that may be sitting on the backlog queue of the old socket toward the same association. Signed-off-by: Vladislav Yasevich <vladislav.yasevich@hp.com> Signed-off-by: Sridhar Samudrala <sri@us.ibm.com>
2006-05-19 18:01:18 +00:00
}
/* Handle icmp frag needed error. */
void sctp_icmp_frag_needed(struct sock *sk, struct sctp_association *asoc,
struct sctp_transport *t, __u32 pmtu)
{
if (!t || (t->pathmtu <= pmtu))
return;
if (sock_owned_by_user(sk)) {
asoc->pmtu_pending = 1;
t->pmtu_pending = 1;
return;
}
if (t->param_flags & SPP_PMTUD_ENABLE) {
/* Update transports view of the MTU */
sctp_transport_update_pmtu(sk, t, pmtu);
/* Update association pmtu. */
sctp_assoc_sync_pmtu(sk, asoc);
}
/* Retransmit with the new pmtu setting.
* Normally, if PMTU discovery is disabled, an ICMP Fragmentation
* Needed will never be sent, but if a message was sent before
* PMTU discovery was disabled that was larger than the PMTU, it
* would not be fragmented, so it must be re-transmitted fragmented.
*/
sctp_retransmit(&asoc->outqueue, t, SCTP_RTXR_PMTUD);
}
void sctp_icmp_redirect(struct sock *sk, struct sctp_transport *t,
struct sk_buff *skb)
{
struct dst_entry *dst;
if (!t)
return;
dst = sctp_transport_dst_check(t);
if (dst)
dst->ops->redirect(dst, sk, skb);
}
/*
* SCTP Implementer's Guide, 2.37 ICMP handling procedures
*
* ICMP8) If the ICMP code is a "Unrecognized next header type encountered"
* or a "Protocol Unreachable" treat this message as an abort
* with the T bit set.
*
* This function sends an event to the state machine, which will abort the
* association.
*
*/
void sctp_icmp_proto_unreachable(struct sock *sk,
struct sctp_association *asoc,
struct sctp_transport *t)
{
SCTP_DEBUG_PRINTK("%s\n", __func__);
sctp: Fix a race between ICMP protocol unreachable and connect() ICMP protocol unreachable handling completely disregarded the fact that the user may have locked the socket. It proceeded to destroy the association, even though the user may have held the lock and had a ref on the association. This resulted in the following: Attempt to release alive inet socket f6afcc00 ========================= [ BUG: held lock freed! ] ------------------------- somenu/2672 is freeing memory f6afcc00-f6afcfff, with a lock still held there! (sk_lock-AF_INET){+.+.+.}, at: [<c122098a>] sctp_connect+0x13/0x4c 1 lock held by somenu/2672: #0: (sk_lock-AF_INET){+.+.+.}, at: [<c122098a>] sctp_connect+0x13/0x4c stack backtrace: Pid: 2672, comm: somenu Not tainted 2.6.32-telco #55 Call Trace: [<c1232266>] ? printk+0xf/0x11 [<c1038553>] debug_check_no_locks_freed+0xce/0xff [<c10620b4>] kmem_cache_free+0x21/0x66 [<c1185f25>] __sk_free+0x9d/0xab [<c1185f9c>] sk_free+0x1c/0x1e [<c1216e38>] sctp_association_put+0x32/0x89 [<c1220865>] __sctp_connect+0x36d/0x3f4 [<c122098a>] ? sctp_connect+0x13/0x4c [<c102d073>] ? autoremove_wake_function+0x0/0x33 [<c12209a8>] sctp_connect+0x31/0x4c [<c11d1e80>] inet_dgram_connect+0x4b/0x55 [<c11834fa>] sys_connect+0x54/0x71 [<c103a3a2>] ? lock_release_non_nested+0x88/0x239 [<c1054026>] ? might_fault+0x42/0x7c [<c1054026>] ? might_fault+0x42/0x7c [<c11847ab>] sys_socketcall+0x6d/0x178 [<c10da994>] ? trace_hardirqs_on_thunk+0xc/0x10 [<c1002959>] syscall_call+0x7/0xb This was because the sctp_wait_for_connect() would aqcure the socket lock and then proceed to release the last reference count on the association, thus cause the fully destruction path to finish freeing the socket. The simplest solution is to start a very short timer in case the socket is owned by user. When the timer expires, we can do some verification and be able to do the release properly. Signed-off-by: Vlad Yasevich <vladislav.yasevich@hp.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2010-05-06 07:56:07 +00:00
if (sock_owned_by_user(sk)) {
if (timer_pending(&t->proto_unreach_timer))
return;
else {
if (!mod_timer(&t->proto_unreach_timer,
jiffies + (HZ/20)))
sctp_association_hold(asoc);
}
} else {
if (timer_pending(&t->proto_unreach_timer) &&
del_timer(&t->proto_unreach_timer))
sctp_association_put(asoc);
sctp: Fix a race between ICMP protocol unreachable and connect() ICMP protocol unreachable handling completely disregarded the fact that the user may have locked the socket. It proceeded to destroy the association, even though the user may have held the lock and had a ref on the association. This resulted in the following: Attempt to release alive inet socket f6afcc00 ========================= [ BUG: held lock freed! ] ------------------------- somenu/2672 is freeing memory f6afcc00-f6afcfff, with a lock still held there! (sk_lock-AF_INET){+.+.+.}, at: [<c122098a>] sctp_connect+0x13/0x4c 1 lock held by somenu/2672: #0: (sk_lock-AF_INET){+.+.+.}, at: [<c122098a>] sctp_connect+0x13/0x4c stack backtrace: Pid: 2672, comm: somenu Not tainted 2.6.32-telco #55 Call Trace: [<c1232266>] ? printk+0xf/0x11 [<c1038553>] debug_check_no_locks_freed+0xce/0xff [<c10620b4>] kmem_cache_free+0x21/0x66 [<c1185f25>] __sk_free+0x9d/0xab [<c1185f9c>] sk_free+0x1c/0x1e [<c1216e38>] sctp_association_put+0x32/0x89 [<c1220865>] __sctp_connect+0x36d/0x3f4 [<c122098a>] ? sctp_connect+0x13/0x4c [<c102d073>] ? autoremove_wake_function+0x0/0x33 [<c12209a8>] sctp_connect+0x31/0x4c [<c11d1e80>] inet_dgram_connect+0x4b/0x55 [<c11834fa>] sys_connect+0x54/0x71 [<c103a3a2>] ? lock_release_non_nested+0x88/0x239 [<c1054026>] ? might_fault+0x42/0x7c [<c1054026>] ? might_fault+0x42/0x7c [<c11847ab>] sys_socketcall+0x6d/0x178 [<c10da994>] ? trace_hardirqs_on_thunk+0xc/0x10 [<c1002959>] syscall_call+0x7/0xb This was because the sctp_wait_for_connect() would aqcure the socket lock and then proceed to release the last reference count on the association, thus cause the fully destruction path to finish freeing the socket. The simplest solution is to start a very short timer in case the socket is owned by user. When the timer expires, we can do some verification and be able to do the release properly. Signed-off-by: Vlad Yasevich <vladislav.yasevich@hp.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2010-05-06 07:56:07 +00:00
sctp_do_sm(SCTP_EVENT_T_OTHER,
SCTP_ST_OTHER(SCTP_EVENT_ICMP_PROTO_UNREACH),
asoc->state, asoc->ep, asoc, t,
GFP_ATOMIC);
}
}
/* Common lookup code for icmp/icmpv6 error handler. */
struct sock *sctp_err_lookup(int family, struct sk_buff *skb,
struct sctphdr *sctphdr,
struct sctp_association **app,
struct sctp_transport **tpp)
{
union sctp_addr saddr;
union sctp_addr daddr;
struct sctp_af *af;
struct sock *sk = NULL;
struct sctp_association *asoc;
struct sctp_transport *transport = NULL;
struct sctp_init_chunk *chunkhdr;
__u32 vtag = ntohl(sctphdr->vtag);
int len = skb->len - ((void *)sctphdr - (void *)skb->data);
*app = NULL; *tpp = NULL;
af = sctp_get_af_specific(family);
if (unlikely(!af)) {
return NULL;
}
/* Initialize local addresses for lookups. */
af->from_skb(&saddr, skb, 1);
af->from_skb(&daddr, skb, 0);
/* Look for an association that matches the incoming ICMP error
* packet.
*/
asoc = __sctp_lookup_association(&saddr, &daddr, &transport);
if (!asoc)
return NULL;
sk = asoc->base.sk;
/* RFC 4960, Appendix C. ICMP Handling
*
* ICMP6) An implementation MUST validate that the Verification Tag
* contained in the ICMP message matches the Verification Tag of
* the peer. If the Verification Tag is not 0 and does NOT
* match, discard the ICMP message. If it is 0 and the ICMP
* message contains enough bytes to verify that the chunk type is
* an INIT chunk and that the Initiate Tag matches the tag of the
* peer, continue with ICMP7. If the ICMP message is too short
* or the chunk type or the Initiate Tag does not match, silently
* discard the packet.
*/
if (vtag == 0) {
chunkhdr = (void *)sctphdr + sizeof(struct sctphdr);
if (len < sizeof(struct sctphdr) + sizeof(sctp_chunkhdr_t)
+ sizeof(__be32) ||
chunkhdr->chunk_hdr.type != SCTP_CID_INIT ||
ntohl(chunkhdr->init_hdr.init_tag) != asoc->c.my_vtag) {
goto out;
}
} else if (vtag != asoc->c.peer_vtag) {
goto out;
}
sctp_bh_lock_sock(sk);
/* If too many ICMPs get dropped on busy
* servers this needs to be solved differently.
*/
if (sock_owned_by_user(sk))
NET_INC_STATS_BH(&init_net, LINUX_MIB_LOCKDROPPEDICMPS);
*app = asoc;
*tpp = transport;
return sk;
out:
if (asoc)
sctp_association_put(asoc);
return NULL;
}
/* Common cleanup code for icmp/icmpv6 error handler. */
void sctp_err_finish(struct sock *sk, struct sctp_association *asoc)
{
sctp_bh_unlock_sock(sk);
if (asoc)
sctp_association_put(asoc);
}
/*
* This routine is called by the ICMP module when it gets some
* sort of error condition. If err < 0 then the socket should
* be closed and the error returned to the user. If err > 0
* it's just the icmp type << 8 | icmp code. After adjustment
* header points to the first 8 bytes of the sctp header. We need
* to find the appropriate port.
*
* The locking strategy used here is very "optimistic". When
* someone else accesses the socket the ICMP is just dropped
* and for some paths there is no check at all.
* A more general error queue to queue errors for later handling
* is probably better.
*
*/
void sctp_v4_err(struct sk_buff *skb, __u32 info)
{
const struct iphdr *iph = (const struct iphdr *)skb->data;
const int ihlen = iph->ihl * 4;
const int type = icmp_hdr(skb)->type;
const int code = icmp_hdr(skb)->code;
struct sock *sk;
struct sctp_association *asoc = NULL;
struct sctp_transport *transport;
struct inet_sock *inet;
[SK_BUFF]: Use offsets for skb->{mac,network,transport}_header on 64bit architectures With this we save 8 bytes per network packet, leaving a 4 bytes hole to be used in further shrinking work, likely with the offsetization of other pointers, such as ->{data,tail,end}, at the cost of adds, that were minimized by the usual practice of setting skb->{mac,nh,n}.raw to a local variable that is then accessed multiple times in each function, it also is not more expensive than before with regards to most of the handling of such headers, like setting one of these headers to another (transport to network, etc), or subtracting, adding to/from it, comparing them, etc. Now we have this layout for sk_buff on a x86_64 machine: [acme@mica net-2.6.22]$ pahole vmlinux sk_buff struct sk_buff { struct sk_buff * next; /* 0 8 */ struct sk_buff * prev; /* 8 8 */ struct rb_node rb; /* 16 24 */ struct sock * sk; /* 40 8 */ ktime_t tstamp; /* 48 8 */ struct net_device * dev; /* 56 8 */ /* --- cacheline 1 boundary (64 bytes) --- */ struct net_device * input_dev; /* 64 8 */ sk_buff_data_t transport_header; /* 72 4 */ sk_buff_data_t network_header; /* 76 4 */ sk_buff_data_t mac_header; /* 80 4 */ /* XXX 4 bytes hole, try to pack */ struct dst_entry * dst; /* 88 8 */ struct sec_path * sp; /* 96 8 */ char cb[48]; /* 104 48 */ /* cacheline 2 boundary (128 bytes) was 24 bytes ago*/ unsigned int len; /* 152 4 */ unsigned int data_len; /* 156 4 */ unsigned int mac_len; /* 160 4 */ union { __wsum csum; /* 4 */ __u32 csum_offset; /* 4 */ }; /* 164 4 */ __u32 priority; /* 168 4 */ __u8 local_df:1; /* 172 1 */ __u8 cloned:1; /* 172 1 */ __u8 ip_summed:2; /* 172 1 */ __u8 nohdr:1; /* 172 1 */ __u8 nfctinfo:3; /* 172 1 */ __u8 pkt_type:3; /* 173 1 */ __u8 fclone:2; /* 173 1 */ __u8 ipvs_property:1; /* 173 1 */ /* XXX 2 bits hole, try to pack */ __be16 protocol; /* 174 2 */ void (*destructor)(struct sk_buff *); /* 176 8 */ struct nf_conntrack * nfct; /* 184 8 */ /* --- cacheline 3 boundary (192 bytes) --- */ struct sk_buff * nfct_reasm; /* 192 8 */ struct nf_bridge_info *nf_bridge; /* 200 8 */ __u16 tc_index; /* 208 2 */ __u16 tc_verd; /* 210 2 */ dma_cookie_t dma_cookie; /* 212 4 */ __u32 secmark; /* 216 4 */ __u32 mark; /* 220 4 */ unsigned int truesize; /* 224 4 */ atomic_t users; /* 228 4 */ unsigned char * head; /* 232 8 */ unsigned char * data; /* 240 8 */ unsigned char * tail; /* 248 8 */ /* --- cacheline 4 boundary (256 bytes) --- */ unsigned char * end; /* 256 8 */ }; /* size: 264, cachelines: 5 */ /* sum members: 260, holes: 1, sum holes: 4 */ /* bit holes: 1, sum bit holes: 2 bits */ /* last cacheline: 8 bytes */ On 32 bits nothing changes, and pointers continue to be used with the compiler turning all this abstraction layer into dust. But there are some sk_buff validation tricks that are now possible, humm... :-) Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2007-04-11 04:22:35 +00:00
sk_buff_data_t saveip, savesctp;
int err;
if (skb->len < ihlen + 8) {
ICMP_INC_STATS_BH(&init_net, ICMP_MIB_INERRORS);
return;
}
/* Fix up skb to look at the embedded net header. */
saveip = skb->network_header;
savesctp = skb->transport_header;
skb_reset_network_header(skb);
skb_set_transport_header(skb, ihlen);
sk = sctp_err_lookup(AF_INET, skb, sctp_hdr(skb), &asoc, &transport);
[SK_BUFF]: Use offsets for skb->{mac,network,transport}_header on 64bit architectures With this we save 8 bytes per network packet, leaving a 4 bytes hole to be used in further shrinking work, likely with the offsetization of other pointers, such as ->{data,tail,end}, at the cost of adds, that were minimized by the usual practice of setting skb->{mac,nh,n}.raw to a local variable that is then accessed multiple times in each function, it also is not more expensive than before with regards to most of the handling of such headers, like setting one of these headers to another (transport to network, etc), or subtracting, adding to/from it, comparing them, etc. Now we have this layout for sk_buff on a x86_64 machine: [acme@mica net-2.6.22]$ pahole vmlinux sk_buff struct sk_buff { struct sk_buff * next; /* 0 8 */ struct sk_buff * prev; /* 8 8 */ struct rb_node rb; /* 16 24 */ struct sock * sk; /* 40 8 */ ktime_t tstamp; /* 48 8 */ struct net_device * dev; /* 56 8 */ /* --- cacheline 1 boundary (64 bytes) --- */ struct net_device * input_dev; /* 64 8 */ sk_buff_data_t transport_header; /* 72 4 */ sk_buff_data_t network_header; /* 76 4 */ sk_buff_data_t mac_header; /* 80 4 */ /* XXX 4 bytes hole, try to pack */ struct dst_entry * dst; /* 88 8 */ struct sec_path * sp; /* 96 8 */ char cb[48]; /* 104 48 */ /* cacheline 2 boundary (128 bytes) was 24 bytes ago*/ unsigned int len; /* 152 4 */ unsigned int data_len; /* 156 4 */ unsigned int mac_len; /* 160 4 */ union { __wsum csum; /* 4 */ __u32 csum_offset; /* 4 */ }; /* 164 4 */ __u32 priority; /* 168 4 */ __u8 local_df:1; /* 172 1 */ __u8 cloned:1; /* 172 1 */ __u8 ip_summed:2; /* 172 1 */ __u8 nohdr:1; /* 172 1 */ __u8 nfctinfo:3; /* 172 1 */ __u8 pkt_type:3; /* 173 1 */ __u8 fclone:2; /* 173 1 */ __u8 ipvs_property:1; /* 173 1 */ /* XXX 2 bits hole, try to pack */ __be16 protocol; /* 174 2 */ void (*destructor)(struct sk_buff *); /* 176 8 */ struct nf_conntrack * nfct; /* 184 8 */ /* --- cacheline 3 boundary (192 bytes) --- */ struct sk_buff * nfct_reasm; /* 192 8 */ struct nf_bridge_info *nf_bridge; /* 200 8 */ __u16 tc_index; /* 208 2 */ __u16 tc_verd; /* 210 2 */ dma_cookie_t dma_cookie; /* 212 4 */ __u32 secmark; /* 216 4 */ __u32 mark; /* 220 4 */ unsigned int truesize; /* 224 4 */ atomic_t users; /* 228 4 */ unsigned char * head; /* 232 8 */ unsigned char * data; /* 240 8 */ unsigned char * tail; /* 248 8 */ /* --- cacheline 4 boundary (256 bytes) --- */ unsigned char * end; /* 256 8 */ }; /* size: 264, cachelines: 5 */ /* sum members: 260, holes: 1, sum holes: 4 */ /* bit holes: 1, sum bit holes: 2 bits */ /* last cacheline: 8 bytes */ On 32 bits nothing changes, and pointers continue to be used with the compiler turning all this abstraction layer into dust. But there are some sk_buff validation tricks that are now possible, humm... :-) Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2007-04-11 04:22:35 +00:00
/* Put back, the original values. */
skb->network_header = saveip;
skb->transport_header = savesctp;
if (!sk) {
ICMP_INC_STATS_BH(&init_net, ICMP_MIB_INERRORS);
return;
}
/* Warning: The sock lock is held. Remember to call
* sctp_err_finish!
*/
switch (type) {
case ICMP_PARAMETERPROB:
err = EPROTO;
break;
case ICMP_DEST_UNREACH:
if (code > NR_ICMP_UNREACH)
goto out_unlock;
/* PMTU discovery (RFC1191) */
if (ICMP_FRAG_NEEDED == code) {
sctp_icmp_frag_needed(sk, asoc, transport, info);
goto out_unlock;
}
else {
if (ICMP_PROT_UNREACH == code) {
sctp_icmp_proto_unreachable(sk, asoc,
transport);
goto out_unlock;
}
}
err = icmp_err_convert[code].errno;
break;
case ICMP_TIME_EXCEEDED:
/* Ignore any time exceeded errors due to fragment reassembly
* timeouts.
*/
if (ICMP_EXC_FRAGTIME == code)
goto out_unlock;
err = EHOSTUNREACH;
break;
case ICMP_REDIRECT:
sctp_icmp_redirect(sk, transport, skb);
err = 0;
break;
default:
goto out_unlock;
}
inet = inet_sk(sk);
if (!sock_owned_by_user(sk) && inet->recverr) {
sk->sk_err = err;
sk->sk_error_report(sk);
} else { /* Only an error on timeout */
sk->sk_err_soft = err;
}
out_unlock:
sctp_err_finish(sk, asoc);
}
/*
* RFC 2960, 8.4 - Handle "Out of the blue" Packets.
*
* This function scans all the chunks in the OOTB packet to determine if
* the packet should be discarded right away. If a response might be needed
* for this packet, or, if further processing is possible, the packet will
* be queued to a proper inqueue for the next phase of handling.
*
* Output:
* Return 0 - If further processing is needed.
* Return 1 - If the packet can be discarded right away.
*/
static int sctp_rcv_ootb(struct sk_buff *skb)
{
sctp_chunkhdr_t *ch;
__u8 *ch_end;
ch = (sctp_chunkhdr_t *) skb->data;
/* Scan through all the chunks in the packet. */
do {
/* Break out if chunk length is less then minimal. */
if (ntohs(ch->length) < sizeof(sctp_chunkhdr_t))
break;
ch_end = ((__u8 *)ch) + WORD_ROUND(ntohs(ch->length));
if (ch_end > skb_tail_pointer(skb))
break;
/* RFC 8.4, 2) If the OOTB packet contains an ABORT chunk, the
* receiver MUST silently discard the OOTB packet and take no
* further action.
*/
if (SCTP_CID_ABORT == ch->type)
goto discard;
/* RFC 8.4, 6) If the packet contains a SHUTDOWN COMPLETE
* chunk, the receiver should silently discard the packet
* and take no further action.
*/
if (SCTP_CID_SHUTDOWN_COMPLETE == ch->type)
goto discard;
/* RFC 4460, 2.11.2
* This will discard packets with INIT chunk bundled as
* subsequent chunks in the packet. When INIT is first,
* the normal INIT processing will discard the chunk.
*/
if (SCTP_CID_INIT == ch->type && (void *)ch != skb->data)
goto discard;
ch = (sctp_chunkhdr_t *) ch_end;
} while (ch_end < skb_tail_pointer(skb));
return 0;
discard:
return 1;
}
/* Insert endpoint into the hash table. */
static void __sctp_hash_endpoint(struct sctp_endpoint *ep)
{
struct sctp_ep_common *epb;
struct sctp_hashbucket *head;
epb = &ep->base;
epb->hashent = sctp_ep_hashfn(epb->bind_addr.port);
head = &sctp_ep_hashtable[epb->hashent];
sctp_write_lock(&head->lock);
hlist_add_head(&epb->node, &head->chain);
sctp_write_unlock(&head->lock);
}
/* Add an endpoint to the hash. Local BH-safe. */
void sctp_hash_endpoint(struct sctp_endpoint *ep)
{
sctp_local_bh_disable();
__sctp_hash_endpoint(ep);
sctp_local_bh_enable();
}
/* Remove endpoint from the hash table. */
static void __sctp_unhash_endpoint(struct sctp_endpoint *ep)
{
struct sctp_hashbucket *head;
struct sctp_ep_common *epb;
epb = &ep->base;
epb->hashent = sctp_ep_hashfn(epb->bind_addr.port);
head = &sctp_ep_hashtable[epb->hashent];
sctp_write_lock(&head->lock);
sctp: Fix list corruption resulting from freeing an association on a list A few days ago Dave Jones reported this oops: [22766.294255] general protection fault: 0000 [#1] PREEMPT SMP [22766.295376] CPU 0 [22766.295384] Modules linked in: [22766.387137] ffffffffa169f292 6b6b6b6b6b6b6b6b ffff880147c03a90 ffff880147c03a74 [22766.387135] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 00000000000 [22766.387136] Process trinity-watchdo (pid: 10896, threadinfo ffff88013e7d2000, [22766.387137] Stack: [22766.387140] ffff880147c03a10 [22766.387140] ffffffffa169f2b6 [22766.387140] ffff88013ed95728 [22766.387143] 0000000000000002 [22766.387143] 0000000000000000 [22766.387143] ffff880003fad062 [22766.387144] ffff88013c120000 [22766.387144] [22766.387145] Call Trace: [22766.387145] <IRQ> [22766.387150] [<ffffffffa169f292>] ? __sctp_lookup_association+0x62/0xd0 [sctp] [22766.387154] [<ffffffffa169f2b6>] __sctp_lookup_association+0x86/0xd0 [sctp] [22766.387157] [<ffffffffa169f597>] sctp_rcv+0x207/0xbb0 [sctp] [22766.387161] [<ffffffff810d4da8>] ? trace_hardirqs_off_caller+0x28/0xd0 [22766.387163] [<ffffffff815827e3>] ? nf_hook_slow+0x133/0x210 [22766.387166] [<ffffffff815902fc>] ? ip_local_deliver_finish+0x4c/0x4c0 [22766.387168] [<ffffffff8159043d>] ip_local_deliver_finish+0x18d/0x4c0 [22766.387169] [<ffffffff815902fc>] ? ip_local_deliver_finish+0x4c/0x4c0 [22766.387171] [<ffffffff81590a07>] ip_local_deliver+0x47/0x80 [22766.387172] [<ffffffff8158fd80>] ip_rcv_finish+0x150/0x680 [22766.387174] [<ffffffff81590c54>] ip_rcv+0x214/0x320 [22766.387176] [<ffffffff81558c07>] __netif_receive_skb+0x7b7/0x910 [22766.387178] [<ffffffff8155856c>] ? __netif_receive_skb+0x11c/0x910 [22766.387180] [<ffffffff810d423e>] ? put_lock_stats.isra.25+0xe/0x40 [22766.387182] [<ffffffff81558f83>] netif_receive_skb+0x23/0x1f0 [22766.387183] [<ffffffff815596a9>] ? dev_gro_receive+0x139/0x440 [22766.387185] [<ffffffff81559280>] napi_skb_finish+0x70/0xa0 [22766.387187] [<ffffffff81559cb5>] napi_gro_receive+0xf5/0x130 [22766.387218] [<ffffffffa01c4679>] e1000_receive_skb+0x59/0x70 [e1000e] [22766.387242] [<ffffffffa01c5aab>] e1000_clean_rx_irq+0x28b/0x460 [e1000e] [22766.387266] [<ffffffffa01c9c18>] e1000e_poll+0x78/0x430 [e1000e] [22766.387268] [<ffffffff81559fea>] net_rx_action+0x1aa/0x3d0 [22766.387270] [<ffffffff810a495f>] ? account_system_vtime+0x10f/0x130 [22766.387273] [<ffffffff810734d0>] __do_softirq+0xe0/0x420 [22766.387275] [<ffffffff8169826c>] call_softirq+0x1c/0x30 [22766.387278] [<ffffffff8101db15>] do_softirq+0xd5/0x110 [22766.387279] [<ffffffff81073bc5>] irq_exit+0xd5/0xe0 [22766.387281] [<ffffffff81698b03>] do_IRQ+0x63/0xd0 [22766.387283] [<ffffffff8168ee2f>] common_interrupt+0x6f/0x6f [22766.387283] <EOI> [22766.387284] [22766.387285] [<ffffffff8168eed9>] ? retint_swapgs+0x13/0x1b [22766.387285] Code: c0 90 5d c3 66 0f 1f 44 00 00 4c 89 c8 5d c3 0f 1f 00 55 48 89 e5 48 83 ec 20 48 89 5d e8 4c 89 65 f0 4c 89 6d f8 66 66 66 66 90 <0f> b7 87 98 00 00 00 48 89 fb 49 89 f5 66 c1 c0 08 66 39 46 02 [22766.387307] [22766.387307] RIP [22766.387311] [<ffffffffa168a2c9>] sctp_assoc_is_match+0x19/0x90 [sctp] [22766.387311] RSP <ffff880147c039b0> [22766.387142] ffffffffa16ab120 [22766.599537] ---[ end trace 3f6dae82e37b17f5 ]--- [22766.601221] Kernel panic - not syncing: Fatal exception in interrupt It appears from his analysis and some staring at the code that this is likely occuring because an association is getting freed while still on the sctp_assoc_hashtable. As a result, we get a gpf when traversing the hashtable while a freed node corrupts part of the list. Nominally I would think that an mibalanced refcount was responsible for this, but I can't seem to find any obvious imbalance. What I did note however was that the two places where we create an association using sctp_primitive_ASSOCIATE (__sctp_connect and sctp_sendmsg), have failure paths which free a newly created association after calling sctp_primitive_ASSOCIATE. sctp_primitive_ASSOCIATE brings us into the sctp_sf_do_prm_asoc path, which issues a SCTP_CMD_NEW_ASOC side effect, which in turn adds a new association to the aforementioned hash table. the sctp command interpreter that process side effects has not way to unwind previously processed commands, so freeing the association from the __sctp_connect or sctp_sendmsg error path would lead to a freed association remaining on this hash table. I've fixed this but modifying sctp_[un]hash_established to use hlist_del_init, which allows us to proerly use hlist_unhashed to check if the node is on a hashlist safely during a delete. That in turn alows us to safely call sctp_unhash_established in the __sctp_connect and sctp_sendmsg error paths before freeing them, regardles of what the associations state is on the hash list. I noted, while I was doing this, that the __sctp_unhash_endpoint was using hlist_unhsashed in a simmilar fashion, but never nullified any removed nodes pointers to make that function work properly, so I fixed that up in a simmilar fashion. I attempted to test this using a virtual guest running the SCTP_RR test from netperf in a loop while running the trinity fuzzer, both in a loop. I wasn't able to recreate the problem prior to this fix, nor was I able to trigger the failure after (neither of which I suppose is suprising). Given the trace above however, I think its likely that this is what we hit. Signed-off-by: Neil Horman <nhorman@tuxdriver.com> Reported-by: davej@redhat.com CC: davej@redhat.com CC: "David S. Miller" <davem@davemloft.net> CC: Vlad Yasevich <vyasevich@gmail.com> CC: Sridhar Samudrala <sri@us.ibm.com> CC: linux-sctp@vger.kernel.org Signed-off-by: David S. Miller <davem@davemloft.net>
2012-07-16 09:13:51 +00:00
hlist_del_init(&epb->node);
sctp_write_unlock(&head->lock);
}
/* Remove endpoint from the hash. Local BH-safe. */
void sctp_unhash_endpoint(struct sctp_endpoint *ep)
{
sctp_local_bh_disable();
__sctp_unhash_endpoint(ep);
sctp_local_bh_enable();
}
/* Look up an endpoint. */
static struct sctp_endpoint *__sctp_rcv_lookup_endpoint(const union sctp_addr *laddr)
{
struct sctp_hashbucket *head;
struct sctp_ep_common *epb;
struct sctp_endpoint *ep;
struct hlist_node *node;
int hash;
hash = sctp_ep_hashfn(ntohs(laddr->v4.sin_port));
head = &sctp_ep_hashtable[hash];
read_lock(&head->lock);
sctp_for_each_hentry(epb, node, &head->chain) {
ep = sctp_ep(epb);
if (sctp_endpoint_is_match(ep, laddr))
goto hit;
}
ep = sctp_sk((sctp_get_ctl_sock()))->ep;
hit:
sctp_endpoint_hold(ep);
read_unlock(&head->lock);
return ep;
}
/* Insert association into the hash table. */
static void __sctp_hash_established(struct sctp_association *asoc)
{
struct sctp_ep_common *epb;
struct sctp_hashbucket *head;
epb = &asoc->base;
/* Calculate which chain this entry will belong to. */
epb->hashent = sctp_assoc_hashfn(epb->bind_addr.port, asoc->peer.port);
head = &sctp_assoc_hashtable[epb->hashent];
sctp_write_lock(&head->lock);
hlist_add_head(&epb->node, &head->chain);
sctp_write_unlock(&head->lock);
}
/* Add an association to the hash. Local BH-safe. */
void sctp_hash_established(struct sctp_association *asoc)
{
if (asoc->temp)
return;
sctp_local_bh_disable();
__sctp_hash_established(asoc);
sctp_local_bh_enable();
}
/* Remove association from the hash table. */
static void __sctp_unhash_established(struct sctp_association *asoc)
{
struct sctp_hashbucket *head;
struct sctp_ep_common *epb;
epb = &asoc->base;
epb->hashent = sctp_assoc_hashfn(epb->bind_addr.port,
asoc->peer.port);
head = &sctp_assoc_hashtable[epb->hashent];
sctp_write_lock(&head->lock);
sctp: Fix list corruption resulting from freeing an association on a list A few days ago Dave Jones reported this oops: [22766.294255] general protection fault: 0000 [#1] PREEMPT SMP [22766.295376] CPU 0 [22766.295384] Modules linked in: [22766.387137] ffffffffa169f292 6b6b6b6b6b6b6b6b ffff880147c03a90 ffff880147c03a74 [22766.387135] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 00000000000 [22766.387136] Process trinity-watchdo (pid: 10896, threadinfo ffff88013e7d2000, [22766.387137] Stack: [22766.387140] ffff880147c03a10 [22766.387140] ffffffffa169f2b6 [22766.387140] ffff88013ed95728 [22766.387143] 0000000000000002 [22766.387143] 0000000000000000 [22766.387143] ffff880003fad062 [22766.387144] ffff88013c120000 [22766.387144] [22766.387145] Call Trace: [22766.387145] <IRQ> [22766.387150] [<ffffffffa169f292>] ? __sctp_lookup_association+0x62/0xd0 [sctp] [22766.387154] [<ffffffffa169f2b6>] __sctp_lookup_association+0x86/0xd0 [sctp] [22766.387157] [<ffffffffa169f597>] sctp_rcv+0x207/0xbb0 [sctp] [22766.387161] [<ffffffff810d4da8>] ? trace_hardirqs_off_caller+0x28/0xd0 [22766.387163] [<ffffffff815827e3>] ? nf_hook_slow+0x133/0x210 [22766.387166] [<ffffffff815902fc>] ? ip_local_deliver_finish+0x4c/0x4c0 [22766.387168] [<ffffffff8159043d>] ip_local_deliver_finish+0x18d/0x4c0 [22766.387169] [<ffffffff815902fc>] ? ip_local_deliver_finish+0x4c/0x4c0 [22766.387171] [<ffffffff81590a07>] ip_local_deliver+0x47/0x80 [22766.387172] [<ffffffff8158fd80>] ip_rcv_finish+0x150/0x680 [22766.387174] [<ffffffff81590c54>] ip_rcv+0x214/0x320 [22766.387176] [<ffffffff81558c07>] __netif_receive_skb+0x7b7/0x910 [22766.387178] [<ffffffff8155856c>] ? __netif_receive_skb+0x11c/0x910 [22766.387180] [<ffffffff810d423e>] ? put_lock_stats.isra.25+0xe/0x40 [22766.387182] [<ffffffff81558f83>] netif_receive_skb+0x23/0x1f0 [22766.387183] [<ffffffff815596a9>] ? dev_gro_receive+0x139/0x440 [22766.387185] [<ffffffff81559280>] napi_skb_finish+0x70/0xa0 [22766.387187] [<ffffffff81559cb5>] napi_gro_receive+0xf5/0x130 [22766.387218] [<ffffffffa01c4679>] e1000_receive_skb+0x59/0x70 [e1000e] [22766.387242] [<ffffffffa01c5aab>] e1000_clean_rx_irq+0x28b/0x460 [e1000e] [22766.387266] [<ffffffffa01c9c18>] e1000e_poll+0x78/0x430 [e1000e] [22766.387268] [<ffffffff81559fea>] net_rx_action+0x1aa/0x3d0 [22766.387270] [<ffffffff810a495f>] ? account_system_vtime+0x10f/0x130 [22766.387273] [<ffffffff810734d0>] __do_softirq+0xe0/0x420 [22766.387275] [<ffffffff8169826c>] call_softirq+0x1c/0x30 [22766.387278] [<ffffffff8101db15>] do_softirq+0xd5/0x110 [22766.387279] [<ffffffff81073bc5>] irq_exit+0xd5/0xe0 [22766.387281] [<ffffffff81698b03>] do_IRQ+0x63/0xd0 [22766.387283] [<ffffffff8168ee2f>] common_interrupt+0x6f/0x6f [22766.387283] <EOI> [22766.387284] [22766.387285] [<ffffffff8168eed9>] ? retint_swapgs+0x13/0x1b [22766.387285] Code: c0 90 5d c3 66 0f 1f 44 00 00 4c 89 c8 5d c3 0f 1f 00 55 48 89 e5 48 83 ec 20 48 89 5d e8 4c 89 65 f0 4c 89 6d f8 66 66 66 66 90 <0f> b7 87 98 00 00 00 48 89 fb 49 89 f5 66 c1 c0 08 66 39 46 02 [22766.387307] [22766.387307] RIP [22766.387311] [<ffffffffa168a2c9>] sctp_assoc_is_match+0x19/0x90 [sctp] [22766.387311] RSP <ffff880147c039b0> [22766.387142] ffffffffa16ab120 [22766.599537] ---[ end trace 3f6dae82e37b17f5 ]--- [22766.601221] Kernel panic - not syncing: Fatal exception in interrupt It appears from his analysis and some staring at the code that this is likely occuring because an association is getting freed while still on the sctp_assoc_hashtable. As a result, we get a gpf when traversing the hashtable while a freed node corrupts part of the list. Nominally I would think that an mibalanced refcount was responsible for this, but I can't seem to find any obvious imbalance. What I did note however was that the two places where we create an association using sctp_primitive_ASSOCIATE (__sctp_connect and sctp_sendmsg), have failure paths which free a newly created association after calling sctp_primitive_ASSOCIATE. sctp_primitive_ASSOCIATE brings us into the sctp_sf_do_prm_asoc path, which issues a SCTP_CMD_NEW_ASOC side effect, which in turn adds a new association to the aforementioned hash table. the sctp command interpreter that process side effects has not way to unwind previously processed commands, so freeing the association from the __sctp_connect or sctp_sendmsg error path would lead to a freed association remaining on this hash table. I've fixed this but modifying sctp_[un]hash_established to use hlist_del_init, which allows us to proerly use hlist_unhashed to check if the node is on a hashlist safely during a delete. That in turn alows us to safely call sctp_unhash_established in the __sctp_connect and sctp_sendmsg error paths before freeing them, regardles of what the associations state is on the hash list. I noted, while I was doing this, that the __sctp_unhash_endpoint was using hlist_unhsashed in a simmilar fashion, but never nullified any removed nodes pointers to make that function work properly, so I fixed that up in a simmilar fashion. I attempted to test this using a virtual guest running the SCTP_RR test from netperf in a loop while running the trinity fuzzer, both in a loop. I wasn't able to recreate the problem prior to this fix, nor was I able to trigger the failure after (neither of which I suppose is suprising). Given the trace above however, I think its likely that this is what we hit. Signed-off-by: Neil Horman <nhorman@tuxdriver.com> Reported-by: davej@redhat.com CC: davej@redhat.com CC: "David S. Miller" <davem@davemloft.net> CC: Vlad Yasevich <vyasevich@gmail.com> CC: Sridhar Samudrala <sri@us.ibm.com> CC: linux-sctp@vger.kernel.org Signed-off-by: David S. Miller <davem@davemloft.net>
2012-07-16 09:13:51 +00:00
hlist_del_init(&epb->node);
sctp_write_unlock(&head->lock);
}
/* Remove association from the hash table. Local BH-safe. */
void sctp_unhash_established(struct sctp_association *asoc)
{
if (asoc->temp)
return;
sctp_local_bh_disable();
__sctp_unhash_established(asoc);
sctp_local_bh_enable();
}
/* Look up an association. */
static struct sctp_association *__sctp_lookup_association(
const union sctp_addr *local,
const union sctp_addr *peer,
struct sctp_transport **pt)
{
struct sctp_hashbucket *head;
struct sctp_ep_common *epb;
struct sctp_association *asoc;
struct sctp_transport *transport;
struct hlist_node *node;
int hash;
/* Optimize here for direct hit, only listening connections can
* have wildcards anyways.
*/
hash = sctp_assoc_hashfn(ntohs(local->v4.sin_port), ntohs(peer->v4.sin_port));
head = &sctp_assoc_hashtable[hash];
read_lock(&head->lock);
sctp_for_each_hentry(epb, node, &head->chain) {
asoc = sctp_assoc(epb);
transport = sctp_assoc_is_match(asoc, local, peer);
if (transport)
goto hit;
}
read_unlock(&head->lock);
return NULL;
hit:
*pt = transport;
sctp_association_hold(asoc);
read_unlock(&head->lock);
return asoc;
}
/* Look up an association. BH-safe. */
SCTP_STATIC
struct sctp_association *sctp_lookup_association(const union sctp_addr *laddr,
const union sctp_addr *paddr,
struct sctp_transport **transportp)
{
struct sctp_association *asoc;
sctp_local_bh_disable();
asoc = __sctp_lookup_association(laddr, paddr, transportp);
sctp_local_bh_enable();
return asoc;
}
/* Is there an association matching the given local and peer addresses? */
int sctp_has_association(const union sctp_addr *laddr,
const union sctp_addr *paddr)
{
struct sctp_association *asoc;
struct sctp_transport *transport;
if ((asoc = sctp_lookup_association(laddr, paddr, &transport))) {
sctp_association_put(asoc);
return 1;
}
return 0;
}
/*
* SCTP Implementors Guide, 2.18 Handling of address
* parameters within the INIT or INIT-ACK.
*
* D) When searching for a matching TCB upon reception of an INIT
* or INIT-ACK chunk the receiver SHOULD use not only the
* source address of the packet (containing the INIT or
* INIT-ACK) but the receiver SHOULD also use all valid
* address parameters contained within the chunk.
*
* 2.18.3 Solution description
*
* This new text clearly specifies to an implementor the need
* to look within the INIT or INIT-ACK. Any implementation that
* does not do this, may not be able to establish associations
* in certain circumstances.
*
*/
static struct sctp_association *__sctp_rcv_init_lookup(struct sk_buff *skb,
const union sctp_addr *laddr, struct sctp_transport **transportp)
{
struct sctp_association *asoc;
union sctp_addr addr;
union sctp_addr *paddr = &addr;
struct sctphdr *sh = sctp_hdr(skb);
union sctp_params params;
sctp_init_chunk_t *init;
struct sctp_transport *transport;
struct sctp_af *af;
/*
* This code will NOT touch anything inside the chunk--it is
* strictly READ-ONLY.
*
* RFC 2960 3 SCTP packet Format
*
* Multiple chunks can be bundled into one SCTP packet up to
* the MTU size, except for the INIT, INIT ACK, and SHUTDOWN
* COMPLETE chunks. These chunks MUST NOT be bundled with any
* other chunk in a packet. See Section 6.10 for more details
* on chunk bundling.
*/
/* Find the start of the TLVs and the end of the chunk. This is
* the region we search for address parameters.
*/
init = (sctp_init_chunk_t *)skb->data;
/* Walk the parameters looking for embedded addresses. */
sctp_walk_params(params, init, init_hdr.params) {
/* Note: Ignoring hostname addresses. */
af = sctp_get_af_specific(param_type2af(params.p->type));
if (!af)
continue;
af->from_addr_param(paddr, params.addr, sh->source, 0);
asoc = __sctp_lookup_association(laddr, paddr, &transport);
if (asoc)
return asoc;
}
return NULL;
}
/* ADD-IP, Section 5.2
* When an endpoint receives an ASCONF Chunk from the remote peer
* special procedures may be needed to identify the association the
* ASCONF Chunk is associated with. To properly find the association
* the following procedures SHOULD be followed:
*
* D2) If the association is not found, use the address found in the
* Address Parameter TLV combined with the port number found in the
* SCTP common header. If found proceed to rule D4.
*
* D2-ext) If more than one ASCONF Chunks are packed together, use the
* address found in the ASCONF Address Parameter TLV of each of the
* subsequent ASCONF Chunks. If found, proceed to rule D4.
*/
static struct sctp_association *__sctp_rcv_asconf_lookup(
sctp_chunkhdr_t *ch,
const union sctp_addr *laddr,
__be16 peer_port,
struct sctp_transport **transportp)
{
sctp_addip_chunk_t *asconf = (struct sctp_addip_chunk *)ch;
struct sctp_af *af;
union sctp_addr_param *param;
union sctp_addr paddr;
/* Skip over the ADDIP header and find the Address parameter */
param = (union sctp_addr_param *)(asconf + 1);
af = sctp_get_af_specific(param_type2af(param->p.type));
if (unlikely(!af))
return NULL;
af->from_addr_param(&paddr, param, peer_port, 0);
return __sctp_lookup_association(laddr, &paddr, transportp);
}
/* SCTP-AUTH, Section 6.3:
* If the receiver does not find a STCB for a packet containing an AUTH
* chunk as the first chunk and not a COOKIE-ECHO chunk as the second
* chunk, it MUST use the chunks after the AUTH chunk to look up an existing
* association.
*
* This means that any chunks that can help us identify the association need
* to be looked at to find this association.
*/
static struct sctp_association *__sctp_rcv_walk_lookup(struct sk_buff *skb,
const union sctp_addr *laddr,
struct sctp_transport **transportp)
{
struct sctp_association *asoc = NULL;
sctp_chunkhdr_t *ch;
int have_auth = 0;
unsigned int chunk_num = 1;
__u8 *ch_end;
/* Walk through the chunks looking for AUTH or ASCONF chunks
* to help us find the association.
*/
ch = (sctp_chunkhdr_t *) skb->data;
do {
/* Break out if chunk length is less then minimal. */
if (ntohs(ch->length) < sizeof(sctp_chunkhdr_t))
break;
ch_end = ((__u8 *)ch) + WORD_ROUND(ntohs(ch->length));
if (ch_end > skb_tail_pointer(skb))
break;
switch(ch->type) {
case SCTP_CID_AUTH:
have_auth = chunk_num;
break;
case SCTP_CID_COOKIE_ECHO:
/* If a packet arrives containing an AUTH chunk as
* a first chunk, a COOKIE-ECHO chunk as the second
* chunk, and possibly more chunks after them, and
* the receiver does not have an STCB for that
* packet, then authentication is based on
* the contents of the COOKIE- ECHO chunk.
*/
if (have_auth == 1 && chunk_num == 2)
return NULL;
break;
case SCTP_CID_ASCONF:
if (have_auth || sctp_addip_noauth)
asoc = __sctp_rcv_asconf_lookup(ch, laddr,
sctp_hdr(skb)->source,
transportp);
default:
break;
}
if (asoc)
break;
ch = (sctp_chunkhdr_t *) ch_end;
chunk_num++;
} while (ch_end < skb_tail_pointer(skb));
return asoc;
}
/*
* There are circumstances when we need to look inside the SCTP packet
* for information to help us find the association. Examples
* include looking inside of INIT/INIT-ACK chunks or after the AUTH
* chunks.
*/
static struct sctp_association *__sctp_rcv_lookup_harder(struct sk_buff *skb,
const union sctp_addr *laddr,
struct sctp_transport **transportp)
{
sctp_chunkhdr_t *ch;
ch = (sctp_chunkhdr_t *) skb->data;
/* The code below will attempt to walk the chunk and extract
* parameter information. Before we do that, we need to verify
* that the chunk length doesn't cause overflow. Otherwise, we'll
* walk off the end.
*/
if (WORD_ROUND(ntohs(ch->length)) > skb->len)
return NULL;
/* If this is INIT/INIT-ACK look inside the chunk too. */
switch (ch->type) {
case SCTP_CID_INIT:
case SCTP_CID_INIT_ACK:
return __sctp_rcv_init_lookup(skb, laddr, transportp);
break;
default:
return __sctp_rcv_walk_lookup(skb, laddr, transportp);
break;
}
return NULL;
}
/* Lookup an association for an inbound skb. */
static struct sctp_association *__sctp_rcv_lookup(struct sk_buff *skb,
const union sctp_addr *paddr,
const union sctp_addr *laddr,
struct sctp_transport **transportp)
{
struct sctp_association *asoc;
asoc = __sctp_lookup_association(laddr, paddr, transportp);
/* Further lookup for INIT/INIT-ACK packets.
* SCTP Implementors Guide, 2.18 Handling of address
* parameters within the INIT or INIT-ACK.
*/
if (!asoc)
asoc = __sctp_rcv_lookup_harder(skb, laddr, transportp);
return asoc;
}