Small update with regard to RFC 4340 (references added as documentation):
on Requests, Ack Vectors / Elapsed Time should be ignored.
Length handling of Elapsed Time also simplified.
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This cleans up the consequences of an earlier patch which
introduced the `if IP_DCCP' clause into net/dccp/Kconfig.
The CCID Kconfig menu is sourced within this clause; as a
consequence, all tests of type `depends on IP_DCCP' are now
redundant.
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This patch addresses the following problems:
1. DCCP relies for its proper functioning on having at least one CCID module
enabled (as in TCP plugable congestion control). Currently it is possible to
disable both CCIDs and thus leave the DCCP module in a compiled, but entirely
non-functional state: no sockets can be created when no CCID is available.
Furthermore, the protocol is (again like TCP) not intended to be used without
CCIDs. Last, a non-empty CCID list is needed for doing CCID feature negotiation.
2. Internally the default CCID that is advertised by the Linux host is set to CCID2
(DCCPF_INITIAL_CCID in include/linux/dccp.h). Disabling CCID2 in the Kconfig
menu without changing the defaults leads to a failure `module not found' when
trying to load the dccp module (which internally tries to load the default CCID).
3. The specification (RFC 4340, sec. 10) treats CCID2 somewhat like a
`minimum common denominator'; the specification says that:
* "New connections start with CCID 2 for both endpoints"
* "A DCCP implementation intended for general use, such as an implementation in a
general-purpose operating system kernel, SHOULD implement at least CCID 2.
The intent is to make CCID 2 broadly available for interoperability [...]"
Providing CCID2 as minimum-required CCID (like Reno/Cubic in TCP) thus seems reasonable.
Hence this patch automatically selects CCID2 when DCCP is enabled. Documentation also added.
Discussions with Ian McDonald on this subject are gratefully acknowledged.
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This extends the DCCP socket API by honouring any shutdown(2) option set by the user.
The behaviour is, as much as possible, made consistent with the API for TCP's shutdown.
This patch exploits the information provided by the user via the socket API to reduce
processing costs:
* if the read end is closed (SHUT_RD), it is not necessary to deliver to input CCID;
* if the write end is closed (SHUT_WR), the same idea applies, but with a difference -
as long as the TX queue has not been drained, we need to receive feedback to keep
congestion-control rates up to date. Hence SHUT_WR is honoured only after the last
packet (under congestion control) has been sent;
* although SHUT_RDWR seems nonsensical, it is nevertheless supported in the same manner
as for TCP (and agrees with test for SHUTDOWN_MASK in dccp_poll() in net/dccp/proto.c).
Furthermore, most of the code already honours the sk_shutdown flags (dccp_recvmsg() for
instance sets the read length to 0 if SHUT_RD had been called); CCID handling is now added
to this by the present patch.
There will also no longer be any delivery when the socket is in the final stages, i.e. when
one of dccp_close(), dccp_fin(), or dccp_done() has been called - which is fine since at
that stage the connection is its final stages.
Motivation and background are on http://www.erg.abdn.ac.uk/users/gerrit/dccp/notes/shutdown
A FIXME has been added to notify the other end if SHUT_RD has been set (RFC 4340, 11.7).
Note: There is a comment in inet_shutdown() in net/ipv4/af_inet.c which asks to "make
sure the socket is a TCP socket". This should probably be extended to mean
`TCP or DCCP socket' (the code is also used by UDP and raw sockets).
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
The moving average computation occurs so frequently in the CCID 3 code that
it merits an inline function of its own. This is uses a suggestion by
Arnaldo as per http://www.mail-archive.com/dccp@vger.kernel.org/msg01662.html
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This fixes/updates the handling of idle and application-limited periods in CCID3,
which currently is broken: there is no detection as to how long a sender has been
idle - there is only one flag which is toggled in between function calls.
Being obsolete now, the `idle' flag is removed.
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This patch fixes a previously undiscovered bug; the problem is in computing
the elapsed time as the time between `receiving' the packet (i.e. skb enters
CCID module) and sending feedback:
- there is no layer-processing, queueing, or delay involved,
- hence the elapsed time is in the order of 1 function call
- this is in the dimension of maximally 50..100usec
- which renders the use of elapsed time almost entirely useless.
The fix is simply to ignore such trivial amounts of elapsed time.
As a further advantage, the now useless elapsed_time field can be removed from
the socket, which reduces the socket structure by another four bytes.
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This updates the CCID3 code with regard to two instances of using `MSS' in place of `s':
1. The RFC3390-based initial rate: both rfc3448bis as well as the Faster Restart
draft now consistently use `s' instead of MSS.
2. Now agrees with section 4.2 of rfc3448bis: "If the sender is ready to send data when
it does not yet have a round trip sample, the value of X is set to s bytes per
second, for segment size s [...]"
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Many-many code in the kernel initialized the timer->function
and timer->data together with calling init_timer(timer). There
is already a helper for this. Use it for networking code.
The patch is HUGE, but makes the code 130 lines shorter
(98 insertions(+), 228 deletions(-)).
Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Acked-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
As done two years ago on IP route cache table (commit
22c047ccbc) , we can avoid using one
lock per hash bucket for the huge TCP/DCCP hash tables.
On a typical x86_64 platform, this saves about 2MB or 4MB of ram, for
litle performance differences. (we hit a different cache line for the
rwlock, but then the bucket cache line have a better sharing factor
among cpus, since we dirty it less often). For netstat or ss commands
that want a full scan of hash table, we perform fewer memory accesses.
Using a 'small' table of hashed rwlocks should be more than enough to
provide correct SMP concurrency between different buckets, without
using too much memory. Sizing of this table depends on
num_possible_cpus() and various CONFIG settings.
This patch provides some locking abstraction that may ease a future
work using a different model for TCP/DCCP table.
Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Acked-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Assigning initial values of `0' is redundant when loading a new CCID structure,
since in net/dccp/ccid.c the entire CCID structure is zeroed out prior to
initialisation in ccid_new():
struct ccid {
struct ccid_operations *ccid_ops;
char ccid_priv[0];
};
// ...
if (rx) {
memset(ccid + 1, 0, ccid_ops->ccid_hc_rx_obj_size);
if (ccid->ccid_ops->ccid_hc_rx_init != NULL &&
ccid->ccid_ops->ccid_hc_rx_init(ccid, sk) != 0)
goto out_free_ccid;
} else {
memset(ccid + 1, 0, ccid_ops->ccid_hc_tx_obj_size);
/* analogous to the rx case */
}
This patch therefore removes the redundant assignments. Thanks to Arnaldo for
the inspiration.
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This fixes `unaligned (read) access' errors of the type
Kernel unaligned access at TPC[100f970c] dccp_parse_options+0x4f4/0x7e0 [dccp]
Kernel unaligned access at TPC[1011f2e4] ccid3_hc_tx_parse_options+0x1ac/0x380 [dccp_ccid3]
Kernel unaligned access at TPC[100f9898] dccp_parse_options+0x680/0x880 [dccp]
by using the get_unaligned macro for parsing options.
Commiter note: Preserved the sparse __be{16,32} annotations.
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This adds support for converting the 11 currently defined Reset codes into system
error numbers, which are stored in sk_err for further interpretation.
This makes the externally visible API behaviour similar to TCP, since a client
connecting to a non-existing port will experience ECONNREFUSED.
* Code 0, Unspecified, is interpreted as non-error (0);
* Code 1, Closed (normal termination), also maps into 0;
* Code 2, Aborted, maps into "Connection reset by peer" (ECONNRESET);
* Code 3, No Connection and
Code 7, Connection Refused, map into "Connection refused" (ECONNREFUSED);
* Code 4, Packet Error, maps into "No message of desired type" (ENOMSG);
* Code 5, Option Error, maps into "Illegal byte sequence" (EILSEQ);
* Code 6, Mandatory Error, maps into "Operation not supported on transport endpoint" (EOPNOTSUPP);
* Code 8, Bad Service Code, maps into "Invalid request code" (EBADRQC);
* Code 9, Too Busy, maps into "Too many users" (EUSERS);
* Code 10, Bad Init Cookie, maps into "Invalid request descriptor" (EBADR);
* Code 11, Aggression Penalty, maps into "Quota exceeded" (EDQUOT)
which makes sense in terms of using more than the `fair share' of bandwidth.
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Acked-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This fixes the following problem: client connects to peer which has no DCCP
enabled or loaded; ICMP error messages ("Protocol Unavailable") can be seen
on the wire, but the application hangs. Reason: ICMP packets don't get through
to dccp_v4_err.
When reporting errors, a sequence number check is made for the DCCP packet
that had caused an ICMP error to arrive.
Such checks can not be made if the socket is in state LISTEN, RESPOND (which
in the implementation is the same as LISTEN), or REQUEST, since update_gsr()
has not been called in these states, hence the sequence window is 0..0.
This patch fixes the problem by adding the REQUEST state as another exemption
to the window check. The error reporting now works as expected on connecting.
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Acked-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
Signed-off-by: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
This fixes a problem when analysing erroneous packets in dccp_v{4,6}_err:
* dccp_hdr_seq currently takes an skb
* however, the transport headers in the skb are shifted, due to the
preceding IPv4/v6 header.
Fixed for v4 and v6 by changing dccp_hdr_seq to take a struct dccp_hdr as
argument. Verified that the correct sequence number is now reported in the
error handler.
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Acked-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Just like UDP.
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Leandro Melo de Sales <leandroal@gmail.com>
Signed-off-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
Signed-off-by: David S. Miller <davem@davemloft.net>
Now that we have this new macro, use it where possible.
Signed-off-by: Jean Delvare <jdelvare@suse.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
By adding module aliases to inet_diag, tcp_diag and dccp_diag, we let
them load automatically as needed. This makes tools like "ss" run
faster.
Signed-off-by: Jean Delvare <jdelvare@suse.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
Do not define the sysctl_dccp_sync_ratelimit sysctl variable in the
CONFIG_SYSCTL dependent sysctl.c module - move it to input.c instead.
This fixes the following build bug:
net/built-in.o: In function `dccp_check_seqno':
input.c:(.text+0xbd859): undefined reference to `sysctl_dccp_sync_ratelimit'
distcc[29953] ERROR: compile (null) on localhost failed
make: *** [vmlinux] Error 1
Found via 'make randconfig' build testing.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Acked-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
With all the users of the double pointers removed from the IPv6 input path,
this patch converts all occurances of sk_buff ** to sk_buff * in IPv6 input
handlers.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
This fixes two bugs in processing of connection-Requests in
v{4,6}_conn_request:
1. Due to using the variable `reset_code', the Reset code generated
internally by dccp_parse_options() is overwritten with the
initialised value ("Too Busy") of reset_code, which is not what is
intended.
2. When receiving a connection-Request on a multicast or broadcast
address, no Reset should be generated, to avoid storms of such
packets. Instead of jumping to the `drop' label, the
v{4,6}_conn_request functions now return 0. Below is why in my
understanding this is correct:
When the conn_request function returns < 0, then the caller,
dccp_rcv_state_process(), returns 1. In all instances where
dccp_rcv_state_process is called (dccp_v4_do_rcv, dccp_v6_do_rcv,
and dccp_child_process), a return value of != 0 from
dccp_rcv_state_process() means that a Reset is generated.
If on the other hand the conn_request function returns 0, the
packet is discarded and no Reset is generated.
Note: There may be a related problem when sending the Response, due to
the following.
if (dccp_v6_send_response(sk, req, NULL))
goto drop_and_free;
/* ... */
drop_and_free:
return -1;
In this case, if send_response fails due to transmission errors, the
next thing that is generated is a Reset with a code "Too Busy". I
haven't been able to conjure up such a condition, but it might be good
to change the behaviour here also (not done by this patch).
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
The elapsed time uses u32, but printk was using %d, not %u.
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This
* removes a declaration of a non-existent function
__dccp_minisock_init;
* shifts the initialisation function dccp_minisock_init() from
options.c to minisocks.c, where it is more naturally expected to
be.
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This replaces several uses of standard arithmetic with the DCCP
sequence number arithmetic functions. The problem here is that the
sequence number wrap-around was not taken into consideration.
* Condition "seqp->ccid2s_seq <= prev->ccid2s_seq" has been replaced
by
dccp_delta_seqno(seqp->ccid2s_seq, prev->ccid2s_seq) >= 0
since if seqp is `before' prev, then the delta_seqno() is positive.
* The test whether sequence numbers `a' and `b' are consecutive has
the form
dccp_delta_seqno(a, b) == 1
* Increment of ccid2hctx_rpseq could be done using dccp_inc_seqno(),
but since here the incremented ccid2hctx_rpseq == seqno, used
assignment instead.
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
skb's passed to ccid2_hc_tx_send_packet() are headerless, the packet
type is decided later, in dccp_write_xmit(). Therefore the first test
of the switch/case block is always true, the others are never reached.
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This removes a test for `val < 1' which would only have been triggered
when val < 0, due to a preceding test for 0. Fixed by using an
unsigned type for cwnd (as in TCP) instead.
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This removes an ugly BUG_ON which has been pointed out by Arnaldo.
Instead of freezing up the machine, a `critical' message is now issued
to the system log.
There is potential of doing this more gracefully (eg. there are a few
internal variables which could be updated despite the lack of memory),
but that requires more complicated changes to the algorithm; thus a
`FIXME' has been added.
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This patch simplifies the interface of ccid2_hc_tx_alloc_seq():
* ccid2_hc_tx_alloc_seq() is always called with an argument of
CCID2_SEQBUF_LEN;
* other code - ccid2_hc_tx_check_sanity() - even depends on the
assumption that ccid2_hc_tx_alloc_seq() has been called with this
particular size;
* passing the `gfp_t' argument to ccid2_hc_tx_alloc_seq() is
redundant with gfp_any().
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This just sets the parameter to bool, since debugging messages are
either on or off.
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This enables applications to query the current value of the Maximum
Packet Size via a socket option, suggested as a SHOULD in (RFC 4340,
p. 102).
This socket option is useful to avoid the annoying bail-out via
`-EMSGSIZE'. In particular, as fragmentation is not currently
supported (and its use is partly discouraged in RFC 4340).
With this option, it is possible to size buffers accordingly, e.g.
int buflen = dccp_get_cur_mps(sockfd);
/* or */
if (msgsize > dccp_get_cur_mps(sockfd))
die("message is too large for this path");
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This performs a minor optimisation: when ccid_hc_tx_send_packet
returns a value greater zero, then the same call previously was done
again at the begin of the while loop in dccp_wait_for_ccid.
This patch exploits the available information and schedule-timeouts
directly instead.
Documentation also added.
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Since DCCP requires to close both ends of a connection simultaneously,
permission to write in state DCCP_CLOSING is removed in dccp_sendmsg():
* if the sending end closed, it would encounter a write error anyhow;
* if the other end has closed the connection, it accepts no more data.
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
Signed-off-by: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
This factors code common to dccp_v{4,6}_ctl_send_reset into a separate function,
and adds support for filling in the Data 1 ... Data 3 fields from RFC 4340, 5.6.
It is useful to have this separate, since the following Reset codes will always
be generated from the control socket rather than via dccp_send_reset:
* Code 3, "No Connection", cf. 8.3.1;
* Code 4, "Packet Error" (identification for Data 1 added);
* Code 5, "Option Error" (identification for Data 1..3 added, will be used later);
* Code 6, "Mandatory Error" (same as Option Error);
* Code 7, "Connection Refused" (what on Earth is the difference to "No Connection"?);
* Code 8, "Bad Service Code";
* Code 9, "Too Busy";
* Code 10, "Bad Init Cookie" (not used).
Code 0 is not recommended by the RFC, the following codes would be used in
dccp_send_reset() instead, since they all relate to an established DCCP connection:
* Code 1, "Closed";
* Code 2, "Aborted";
* Code 11, "Aggression Penalty" (12.3).
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
This replaces normal addition with mod-48 addition so that sequence number
wraparound is respected.
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
Signed-off-by: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
This implements a SHOULD from RFC 4340, 7.5.4:
"To protect against denial-of-service attacks, DCCP implementations SHOULD
impose a rate limit on DCCP-Syncs sent in response to sequence-invalid packets,
such as not more than eight DCCP-Syncs per second."
The rate-limit is maintained on a per-socket basis. This is a more stringent
policy than enforcing the rate-limit on a per-source-address basis and
protects against attacks with forged source addresses.
Moreover, the mechanism is deliberately kept simple. In contrast to
xrlim_allow(), bursts of Sync packets in reply to sequence-invalid packets
are not supported. This foils such attacks where the receipt of a Sync
triggers further sequence-invalid packets. (I have tested this mechanism against
xrlim_allow algorithm for Syncs, permitting bursts just increases the problems.)
In order to keep flexibility, the timeout parameter can be set via sysctl; and
the whole mechanism can even be disabled (which is however not recommended).
The algorithm in this patch has been improved with regard to wrapping issues
thanks to a suggestion by Arnaldo.
Commiter note: Rate limited the step 6 DCCP_WARN too, as it says we're
sending a sync.
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
Signed-off-by: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
In this patch, duplicated code is removed for the case when a Reset packet is
sent from a connected socket. This code duplication is between dccp_make_reset
and dccp_transmit_skb, which already contained an (up to now entirely unused)
switch statement to fill in the reset code from the DCCP_SKB_CB.
The only thing that has been removed is the call to dst_clone(dst), since
the queue_xmit functions use sk_dst_cache anyway.
I wasn't sure which purpose inet_sk_rebuild_header served, so I left it in.
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
This adds fields to support the informational Data 1..3 fields of the
DCCP-Reset packets (RFC 4340, 5.6), and makes minor cosmetic changes
to documentation.
Code which fills in these fields follows in subsequent patches, it is
primarily used for reporting option-processing and feature-negotiation
errors.
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
This adds a FIXME to signal that the function dccp_send_delayed_ack is nowhere
used in the entire DCCP/CCID code.
Using a delayed Ack timer is suggested in 11.3 of RFC 4340, but it has also
rather subtle implications for the Ack-Ratio-accounting.
CCID2 does not use this (maybe it should).
I think leaving the function in is good, in case someone wants to implement
this.
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
This moves several instances of testing against NULL into the function which is
used to de-reference the CCID-private data.
Committer note: Made the BUG_ON depend on having CONFIG_IP_DCCP_CCID3_DEBUG, as it
is too much to have this on production code. Also made sure that
the macro is used only after checking if sk_state is not LISTEN,
to make it equivalent to what we had before.
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
Signed-off-by: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
This fixes the code to correspond to RFC 4340, 7.5.4, which states the
exception that a Sync received in state REQUEST generates a Reset (not
a SyncAck).
To achieve this, only a small change is required. Since
dccp_rcv_request_sent_state_process() already uses the correct Reset Code
number 4 ("Packet Error"), we only need to shift the if-statement a few
lines further down.
(To test this case: replace DCCP_PKT_RESPONSE with DCCP_PKT_SYNC
in dccp_make_response.)
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
Signed-off-by: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
The parameter `seq' of dccp_send_sync() is in fact an acknowledgement number
and not a sequence number - thus renamed by this patch into `ackno'.
Secondly, a `critical' warning is added when a Sync/SyncAck could not be sent.
Sanity: I have checked all other functions that are called in dccp_transmit_skb,
there are no clashes with the use of dccpd_ack_seq; no other function is
using this slot at the same time.
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
Signed-off-by: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
This updates sequence number checking with regard to RFC 4340, 7.5.4.
Missing in the code was an exception for sequence-invalid Reset packets,
which get a Sync acknowledging GSR, instead of (as usual) P.seqno.
This can lead to an oscillating ping-pong flood of Reset packets.
In fact, it has been observed on the wire as follows:
1. client establishes connection to server;
2. before server can write to client, client crashes without notifying
the server (NB: now no longer possible due to ABORT function);
3. server sends DCCP-Data packet (has no ackno);
4. client generates Reset "No Connection", seqno=0, increments seqno;
5. server replies with Sync, using ackno = P.seqno;
6. client generates Reset "No Connection" with seqno = ackno + 1;
7. goto (5).
The difference is that now in (5) the server uses GSR. This causes the
Reset sent by the client in (6) to become sequence-valid, so that in (7)
the vicious circle is broken; the Reset is then enqueued and causes the
socket to enter TIMEWAIT state.
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
Signed-off-by: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
This patch is in part required by the next patch; it
* replaces 6 instances of `DCCP_SKB_CB(skb)->dccpd_seq' with `seqno';
* replaces 7 instances of `DCCP_SKB_CB(skb)->dccpd_ack_seq' with `ackno';
* replaces 1 use of dccp_inc_seqno() by unfolding `ADD48' macro in place.
No changes in algorithm, all changes are text replacement/substitution.
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
Signed-off-by: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
The third parameter of dccp_sample_rtt now becomes useless and is removed.
Also combined the subtraction of the timestamp echo and the elapsed time.
This is safe, since (a) presence of timestamp echo is tested first and (b)
elapsed time is either present and non-zero or it is not set and equals 0
due to the memset in dccp_parse_options.
To avoid measuring option-processing time, the timestamp for measuring the
initial Request/Response RTT sample is taken directly when the function is
called (the Linux implementation always adds a timestamp on the Request,
so there is no loss in doing this).
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
Signed-off-by: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
This provides a timesource, conveniently used for DCCP timestamps, which
returns the elapsed time in 10s of microseconds since initialisation.
This makes for a wrap-around time of about 11.9 hours, which should be
sufficient for most applications.
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
This patch reduces the number of timestamps taken in the receive path
for each packet.
The ccid3_hc_tx_update_x() routine is called in
* the receive path for each CCID3-controlled packet
* for the nofeedback timer (if no feedback arrives during 4 RTT)
Currently, when there is no loss, each packet gets timestamped twice.
The patch resolves this by recycling the first timestamp taken on packet
reception for RTT sampling.
When the no_feedback_timer() is called, then the timestamp argument is
simply set to NULL - so that ccid3_hc_tx_update_x() takes care of the logic.
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Gerrit Renker