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* net: Fix (nearly-)kernel-doc comments for various functionsBen Hutchings2012-07-101-0/+1
| | | | | | | | Fix incorrect start markers, wrapped summary lines, missing section breaks, incorrect separators, and some name mismatches. Signed-off-by: Ben Hutchings <bhutchings@solarflare.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* net: cleanup unsigned to unsigned intEric Dumazet2012-04-151-5/+5
| | | | | | | Use of "unsigned int" is preferred to bare "unsigned" in net tree. Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* dccp: Clean up slow-path input processingGerrit Renker2011-07-041-31/+30
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch rearranges the order of statements of the slow-path input processing (i.e. any other state than OPEN), to resolve the following issues. 1. Dependencies: the order of statements now better matches RFC 4340, 8.5, i.e. step 7 is before step 9 (previously 9 was before 7), and parsing options in step 8 (which may consume resources) now comes after step 7. 2. Sequence number checks are omitted if in state LISTEN/REQUEST, due to the note underneath the table in RFC 4340, 7.5.3. As a result, CCID processing is now indeed confined to OPEN/PARTOPEN states, i.e. congestion control is performed only on the flow of data packets. This avoids pathological cases of doing congestion control on those messages which set up and terminate the connection. 3. Packets are now passed on to Ack Vector / CCID processing only after - step 7 (receive unexpected packets), - step 9 (receive Reset), - step 13 (receive CloseReq), - step 14 (receive Close) and only if the state is PARTOPEN. This simplifies CCID processing: - in LISTEN/CLOSED the CCIDs are non-existent; - in RESPOND/REQUEST the CCIDs have not yet been negotiated; - in CLOSEREQ and active-CLOSING the node has already closed this socket; - in passive-CLOSING the client is waiting for its Reset. In the last case, RFC 4340, 8.3 leaves it open to ignore further incoming data, which is the approach taken here. Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
* dccp: fix oops on Reset after closeGerrit Renker2011-03-011-4/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This fixes a bug in the order of dccp_rcv_state_process() that still permitted reception even after closing the socket. A Reset after close thus causes a NULL pointer dereference by not preventing operations on an already torn-down socket. dccp_v4_do_rcv() | | state other than OPEN v dccp_rcv_state_process() | | DCCP_PKT_RESET v dccp_rcv_reset() | v dccp_time_wait() WARNING: at net/ipv4/inet_timewait_sock.c:141 __inet_twsk_hashdance+0x48/0x128() Modules linked in: arc4 ecb carl9170 rt2870sta(C) mac80211 r8712u(C) crc_ccitt ah [<c0038850>] (unwind_backtrace+0x0/0xec) from [<c0055364>] (warn_slowpath_common) [<c0055364>] (warn_slowpath_common+0x4c/0x64) from [<c0055398>] (warn_slowpath_n) [<c0055398>] (warn_slowpath_null+0x1c/0x24) from [<c02b72d0>] (__inet_twsk_hashd) [<c02b72d0>] (__inet_twsk_hashdance+0x48/0x128) from [<c031caa0>] (dccp_time_wai) [<c031caa0>] (dccp_time_wait+0x40/0xc8) from [<c031c15c>] (dccp_rcv_state_proces) [<c031c15c>] (dccp_rcv_state_process+0x120/0x538) from [<c032609c>] (dccp_v4_do_) [<c032609c>] (dccp_v4_do_rcv+0x11c/0x14c) from [<c0286594>] (release_sock+0xac/0) [<c0286594>] (release_sock+0xac/0x110) from [<c031fd34>] (dccp_close+0x28c/0x380) [<c031fd34>] (dccp_close+0x28c/0x380) from [<c02d9a78>] (inet_release+0x64/0x70) The fix is by testing the socket state first. Receiving a packet in Closed state now also produces the required "No connection" Reset reply of RFC 4340, 8.3.1. Reported-and-tested-by: Johan Hovold <jhovold@gmail.com> Cc: stable@kernel.org Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk> Signed-off-by: David S. Miller <davem@davemloft.net>
* dccp: fix return value for sequence-invalid packetsSamuel Jero2011-01-071-1/+1
| | | | | | | | | | Currently dccp_check_seqno returns 0 (indicating a valid packet) if the acknowledgment number is out of bounds and the sync that RFC 4340 mandates at this point is currently being rate-limited. This function should return -1, indicating an invalid packet. Signed-off-by: Samuel Jero <sj323707@ohio.edu> Acked-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
* Merge branch 'master' of ↵David S. Miller2010-12-081-1/+2
|\ | | | | | | | | | | | | | | master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6 Conflicts: drivers/net/wireless/ath/ath9k/ar9003_eeprom.c net/llc/af_llc.c
| * dccp: fix error in updating the GARGerrit Renker2010-11-281-1/+2
| | | | | | | | | | | | | | | | | | This fixes a bug in updating the Greatest Acknowledgment number Received (GAR): the current implementation does not track the greatest received value - lower values in the range AWL..AWH (RFC 4340, 7.5.1) erase higher ones. Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk> Signed-off-by: David S. Miller <davem@davemloft.net>
* | dccp ccid-2: Consolidate Ack-Vector processing within main DCCP moduleGerrit Renker2010-11-151-22/+9
| | | | | | | | | | | | | | | | | | | | | | | | This aggregates Ack Vector processing (handling input and clearing old state) into one function, for the following reasons and benefits: * all Ack Vector-specific processing is now in one place; * duplicated code is removed; * ensuring sanity: from an Ack Vector point of view, it is better to clear the old state first before entering new state; * Ack Event handling happens mostly within the CCIDs, not the main DCCP module. Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
* | dccp ccid-2: Algorithm to update buffer stateGerrit Renker2010-11-151-2/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This provides a routine to consistently update the buffer state when the peer acknowledges receipt of Ack Vectors; updating state in the list of Ack Vectors as well as in the circular buffer. While based on RFC 4340, several additional (and necessary) precautions were added to protect the consistency of the buffer state. These additions are essential, since analysis and experience showed that the basic algorithm was insufficient for this task (which lead to problems that were hard to debug). The algorithm now * deals with HC-sender acknowledging to HC-receiver and vice versa, * keeps track of the last unacknowledged but received seqno in tail_ackno, * has special cases to reset the overflow condition when appropriate, * is protected against receiving older information (would mess up buffer state). Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
* | dccp ccid-2: Ack Vector interface clean-upGerrit Renker2010-11-101-4/+2
|/ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch brings the Ack Vector interface up to date. Its main purpose is to lay the basis for the subsequent patches of this set, which will use the new data structure fields and routines. There are no real algorithmic changes, rather an adaptation: (1) Replaced the static Ack Vector size (2) with a #define so that it can be adapted (with low loss / Ack Ratio, a value of 1 works, so 2 seems to be sufficient for the moment) and added a solution so that computing the ECN nonce will continue to work - even with larger Ack Vectors. (2) Replaced the #defines for Ack Vector states with a complete enum. (3) Replaced #defines to compute Ack Vector length and state with general purpose routines (inlines), and updated code to use these. (4) Added a `tail' field (conversion to circular buffer in subsequent patch). (5) Updated the (outdated) documentation for Ack Vector struct. (6) All sequence number containers now trimmed to 48 bits. (7) Removal of unused bits: * removed dccpav_ack_nonce from struct dccp_ackvec, since this is already redundantly stored in the `dccpavr_ack_nonce' (of Ack Vector record); * removed Elapsed Time for Ack Vectors (it was nowhere used); * replaced semantics of dccpavr_sent_len with dccpavr_ack_runlen, since the code needs to be able to remember the old run length; * reduced the de-/allocation routines (redundant / duplicate tests). Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
* dccp: cosmetics - warning formatGerrit Renker2010-10-121-1/+1
| | | | | | | | | This omits the redundant "DCCP:" in warning messages, since DCCP_WARN() already echoes the function name, avoiding messages like kernel: [10988.766503] dccp_close: DCCP: ABORT -- 209 bytes unread Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
* dccp: fix the adjustments to AWL and SWLGerrit Renker2010-10-121-12/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | | This fixes a problem and a potential loophole with regard to seqno/ackno validity: currently the initial adjustments to AWL/SWL are only performed once at the begin of the connection, during the handshake. Since the Sequence Window feature is always greater than Wmin=32 (7.5.2), it is however necessary to perform these adjustments at least for the first W/W' (variables as per 7.5.1) packets in the lifetime of a connection. This requirement is complicated by the fact that W/W' can change at any time during the lifetime of a connection. Therefore it is better to perform that safety check each time SWL/AWL are updated, as implemented by the patch. A second problem solved by this patch is that the remote/local Sequence Window feature values (which set the bounds for AWL/SWL/SWH) are undefined until the feature negotiation has completed. During the initial handshake we have more stringent sequence number protection; the changes added by this patch effect that {A,S}W{L,H} are within the correct bounds at the instant that feature negotiation completes (since the SeqWin feature activation handlers call dccp_update_gsr/gss()). Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
* dccp: make implementation of Syn-RTT symmetricGerrit Renker2010-06-251-2/+11
| | | | | | | | | | | | | | | | | | This patch is thanks to Andre Noll who reported the issue and helped testing. The Syn-RTT sampled during the initial handshake currently only works for the client sending the DCCP-Request. TFRC penalizes the absence of an RTT sample with a very slow initial speed (1 packet per second), which delays slow-start significantly, resulting in sluggish performance. This patch mirrors the "Syn RTT" principle by adding a timestamp also onto the DCCP-Response, producing an RTT sample when the (Data)Ack completing the handshake arrives. Also changed the documentation to 'TFRC' since Syn RTTs are also used by CCID-4. Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk> Signed-off-by: David S. Miller <davem@davemloft.net>
* net/dccp: expansion of error code sizeYoichi Yuasa2010-05-241-3/+3
| | | | | | | | Because MIPS's EDQUOT value is 1133(0x46d). It's larger than u8. Signed-off-by: Yoichi Yuasa <yuasa@linux-mips.org> Signed-off-by: David S. Miller <davem@davemloft.net>
* Merge branch 'master' of ↵David S. Miller2010-04-111-0/+1
|\ | | | | | | | | | | | | | | | | | | | | | | master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6 Conflicts: drivers/net/stmmac/stmmac_main.c drivers/net/wireless/wl12xx/wl1271_cmd.c drivers/net/wireless/wl12xx/wl1271_main.c drivers/net/wireless/wl12xx/wl1271_spi.c net/core/ethtool.c net/mac80211/scan.c
| * include cleanup: Update gfp.h and slab.h includes to prepare for breaking ↵Tejun Heo2010-03-301-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
* | net: remove trailing space in messagesFrans Pop2010-03-241-1/+1
|/ | | | | Signed-off-by: Frans Pop <elendil@planet.nl> Signed-off-by: David S. Miller <davem@davemloft.net>
* dccp: Integrate the TFRC library with DCCPGerrit Renker2009-01-041-2/+0
| | | | | | | | This patch integrates the TFRC library, which is a dependency of CCID-3 (and CCID-4), with the new use of CCIDs in the DCCP module. Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk> Signed-off-by: David S. Miller <davem@davemloft.net>
* dccp ccid-2: Phase out the use of boolean Ack Vector sysctlGerrit Renker2008-12-081-9/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This removes the use of the sysctl and the minisock variable for the Send Ack Vector feature, as it now is handled fully dynamically via feature negotiation (i.e. when CCID-2 is enabled, Ack Vectors are automatically enabled as per RFC 4341, 4.). Using a sysctl in parallel to this implementation would open the door to crashes, since much of the code relies on tests of the boolean minisock / sysctl variable. Thus, this patch replaces all tests of type if (dccp_msk(sk)->dccpms_send_ack_vector) /* ... */ with if (dp->dccps_hc_rx_ackvec != NULL) /* ... */ The dccps_hc_rx_ackvec is allocated by the dccp_hdlr_ackvec() when feature negotiation concluded that Ack Vectors are to be used on the half-connection. Otherwise, it is NULL (due to dccp_init_sock/dccp_create_openreq_child), so that the test is a valid one. The activation handler for Ack Vectors is called as soon as the feature negotiation has concluded at the * server when the Ack marking the transition RESPOND => OPEN arrives; * client after it has sent its ACK, marking the transition REQUEST => PARTOPEN. Adding the sequence number of the Response packet to the Ack Vector has been removed, since (a) connection establishment implies that the Response has been received; (b) the CCIDs only look at packets received in the (PART)OPEN state, i.e. this entry will always be ignored; (c) it can not be used for anything useful - to detect loss for instance, only packets received after the loss can serve as pseudo-dupacks. There was a FIXME to change the error code when dccp_ackvec_add() fails. I removed this after finding out that: * the check whether ackno < ISN is already made earlier, * this Response is likely the 1st packet with an Ackno that the client gets, * so when dccp_ackvec_add() fails, the reason is likely not a packet error. Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk> Acked-by: Ian McDonald <ian.mcdonald@jandi.co.nz> Signed-off-by: David S. Miller <davem@davemloft.net>
* dccp: Integration of dynamic feature activation - part 3 (client side)Gerrit Renker2008-12-081-4/+26
| | | | | | | | | | | | | | | | | | | | | | | | This integrates feature-activation in the client: 1. When dccp_parse_options() fails, the reset code is already set; request_sent\ _state_process() currently overrides this with `Packet Error', which is not intended - changed to use the reset code supplied by dccp_parse_options(). 2. When feature negotiation fails, the socket should be marked as not usable, so that the application is notified that an error occurred. This is achieved by a new label 'unable_to_proceed': generating an error code of `Aborted', setting the socket state to CLOSED, returning with ECOMM in sk_err. 3. Avoids parsing the Ack twice in Respond state by not doing option processing again in dccp_rcv_respond_partopen_state_process (as option processing has already been done on the request_sock in dccp_check_req). Since this addresses congestion-control initialisation, a corresponding FIXME has been removed. Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk> Acked-by: Ian McDonald <ian.mcdonald@jandi.co.nz> Signed-off-by: David S. Miller <davem@davemloft.net>
* dccp: Per-socket initialisation of feature negotiationGerrit Renker2008-11-041-2/+0
| | | | | | | | | | | | | | | This provides feature-negotiation initialisation for both DCCP sockets and DCCP request_sockets, to support feature negotiation during connection setup. It also resolves a FIXME regarding the congestion control initialisation. Thanks to Wei Yongjun for help with the IPv6 side of this patch. Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk> Acked-by: Ian McDonald <ian.mcdonald@jandi.co.nz> Signed-off-by: David S. Miller <davem@davemloft.net>
* This reverts "Merge branch 'dccp' of git://eden-feed.erg.abdn.ac.uk/dccp_exp"Gerrit Renker2008-09-091-73/+91
| | | | | | as it accentally contained the wrong set of patches. These will be submitted separately. Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
* dccp: Clamping RTT valuesGerrit Renker2008-09-041-10/+1
| | | | | | | | | | | This extracts the clamping part of dccp_sample_rtt() and makes it available to other parts of the code (as e.g. used in the next patch). Note: The function dccp_sample_rtt() now reduces to subtracting the elapsed time. This could be eliminated but would require shorter prefixes and thus is not done by this patch - maybe an idea for later. Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
* dccp: Clean up slow-path input processingGerrit Renker2008-09-041-35/+33
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch rearranges the order of statements of the slow-path input processing (i.e. any other state than OPEN), to resolve the following issues. 1. Dependencies: the order of statements now better matches RFC 4340, 8.5, i.e. step 7 is before step 9 (previously 9 was before 7), and parsing options in step 8 (which can consume resources) now comes after step 7. 2. Bug-fix: in state CLOSED, there should not be any sequence number checking or option processing. This is why the test for CLOSED has been moved after the test for LISTEN. 3. As before sequence number checks are omitted if in state LISTEN/REQUEST, due to the note underneath the table in RFC 4340, 7.5.3. 4. Packets are now passed on to Ack Vector / CCID processing only after - step 7 (receive unexpected packets), - step 9 (receive Reset), - step 13 (receive CloseReq), - step 14 (receive Close) and only if the state is PARTOPEN. This simplifies CCID processing: - in LISTEN/CLOSED the CCIDs are non-existent; - in RESPOND/REQUEST the CCIDs have not yet been negotiated; - in CLOSEREQ and active-CLOSING the node has already closed this socket; - in passive-CLOSING the client is waiting for its Reset. In the last case, RFC 4340, 8.3 leaves it open to ignore further incoming data, which is the approach taken here. As a result of (3), CCID processing is now indeed confined to OPEN/PARTOPEN states, i.e. congestion control is performed only on the flow of data packets. This avoids pathological cases of doing congestion control on those messages which set up and terminate the connection. I have done a few checks to see if this creates a problem in other parts of the code. This seems not to be the case; even if there were one, it would be better to fix it than to perform congestion control on Close/Request/Response messages. Similarly for Ack Vectors (as they depend on the negotiated CCID). Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
* dccp ccid-2: Consolidate Ack-Vector processing within main DCCP moduleGerrit Renker2008-09-041-22/+9
| | | | | | | | | | | | This aggregates Ack Vector processing (handling input and clearing old state) into one function, for the following reasons and benefits: * all Ack Vector-specific processing is now in one place; * duplicated code is removed; * ensuring sanity: from an Ack Vector point of view, it is better to clear the old state first before entering new state; * Ack Event handling happens mostly within the CCIDs, not the main DCCP module. Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
* dccp ccid-2: Algorithm to update buffer stateGerrit Renker2008-09-041-2/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This provides a routine to consistently update the buffer state when the peer acknowledges receipt of Ack Vectors; updating state in the list of Ack Vectors as well as in the circular buffer. While based on RFC 4340, several additional (and necessary) precautions were added to protect the consistency of the buffer state. These additions are essential, since analysis and experience showed that the basic algorithm was insufficient for this task (which lead to problems that were hard to debug). The algorithm now * deals with HC-sender acknowledging to HC-receiver and vice versa, * keeps track of the last unacknowledged but received seqno in tail_ackno, * has special cases to reset the overflow condition when appropriate, * is protected against receiving older information (would mess up buffer state). Note: The older code performed an unnecessary step, where the sender cleared Ack Vector state by parsing the Ack Vector received by the HC-receiver. Doing this was entirely redundant, since * the receiver always puts the full acknowledgment window (groups 2,3 in 11.4.2) into the Ack Vectors it sends; hence the HC-receiver is only interested in the highest state that the HC-sender received; * this means that the acknowledgment number on the (Data)Ack from the HC-sender is sufficient; and work done in parsing earlier state is not necessary, since the later state subsumes the earlier one (see also RFC 4340, A.4). This older interface (dccp_ackvec_parse()) is therefore removed. Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
* dccp ccid-2: Ack Vector interface clean-upGerrit Renker2008-09-041-4/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch brings the Ack Vector interface up to date. Its main purpose is to lay the basis for the subsequent patches of this set, which will use the new data structure fields and routines. There are no real algorithmic changes, rather an adaptation: (1) Replaced the static Ack Vector size (2) with a #define so that it can be adapted (with low loss / Ack Ratio, a value of 1 works, so 2 seems to be sufficient for the moment) and added a solution so that computing the ECN nonce will continue to work - even with larger Ack Vectors. (2) Replaced the #defines for Ack Vector states with a complete enum. (3) Replaced #defines to compute Ack Vector length and state with general purpose routines (inlines), and updated code to use these. (4) Added a `tail' field (conversion to circular buffer in subsequent patch). (5) Updated the (outdated) documentation for Ack Vector struct. (6) All sequence number containers now trimmed to 48 bits. (7) Removal of unused bits: * removed dccpav_ack_nonce from struct dccp_ackvec, since this is already redundantly stored in the `dccpavr_ack_nonce' (of Ack Vector record); * removed Elapsed Time for Ack Vectors (it was nowhere used); * replaced semantics of dccpavr_sent_len with dccpavr_ack_runlen, since the code needs to be able to remember the old run length; * reduced the de-/allocation routines (redundant / duplicate tests). Justification for removing Elapsed Time information [can be removed]: --------------------------------------------------------------------- 1. The Elapsed Time information for Ack Vectors was nowhere used in the code. 2. DCCP does not implement rate-based pacing of acknowledgments. The only recommendation for always including Elapsed Time is in section 11.3 of RFC 4340: "Receivers that rate-pace acknowledgements SHOULD [...] include Elapsed Time options". But such is not the case here. 3. It does not really improve estimation accuracy. The Elapsed Time field only records the time between the arrival of the last acknowledgeable packet and the time the Ack Vector is sent out. Since Linux does not (yet) implement delayed Acks, the time difference will typically be small, since often the arrival of a data packet triggers sending feedback at the HC-receiver. Justification for changes in de-/allocation routines [can be removed]: ---------------------------------------------------------------------- * INIT_LIST_HEAD in dccp_ackvec_record_new was redundant, since the list pointers were later overwritten when the node was added via list_add(); * dccp_ackvec_record_new() was called in a single place only; * calls to list_del_init() before calling dccp_ackvec_record_delete() were redundant, since subsequently the entire element was k-freed; * since all calls to dccp_ackvec_record_delete() were preceded to a call to list_del_init(), the WARN_ON test would never evaluate to true; * since all calls to dccp_ackvec_record_delete() were made from within list_for_each_entry_safe(), the test for avr == NULL was redundant; * list_empty() in ackvec_free was redundant, since the same condition is embedded in the loop condition of the subsequent list_for_each_entry_safe(). Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
* dccp: Fix the adjustments to AWL and SWLGerrit Renker2008-09-041-12/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This fixes a problem and a potential loophole with regard to seqno/ackno validity: the problem is that the initial adjustments to AWL/SWL were only performed at the begin of the connection, during the handshake. Since the Sequence Window feature is always greater than Wmin=32 (7.5.2), it is however necessary to perform these adjustments at least for the first W/W' (variables as per 7.5.1) packets in the lifetime of a connection. This requirement is complicated by the fact that W/W' can change at any time during the lifetime of a connection. Therefore the consequence is to perform this safety check each time SWL/AWL are updated. A second problem solved by this patch is that the remote/local Sequence Window feature values (which set the bounds for AWL/SWL/SWH) are undefined until the feature negotiation has completed. During the initial handshake we have more stringent sequence number protection, the changes added by this patch effect that {A,S}W{L,H} are within the correct bounds at the instant that feature negotiation completes (since the SeqWin feature activation handlers call dccp_update_gsr/gss()). A detailed rationale is below -- can be removed from the commit message. 1. Server sequence number checks during initial handshake --------------------------------------------------------- The server can not use the fields of the listening socket for seqno/ackno checks and thus needs to store all relevant information on a per-connection basis on the dccp_request socket. This is a size-constrained structure and has currently only ISS (dreq_iss) and ISR (dreq_isr) defined. Adding further fields (SW{L,H}, AW{L,H}) would increase the size of the struct and it is questionable whether this will have any practical gain. The currently implemented solution is as follows. * receiving first Request: dccp_v{4,6}_conn_request sets ISR := P.seqno, ISS := dccp_v{4,6}_init_sequence() * sending first Response: dccp_v{4,6}_send_response via dccp_make_response() sets P.seqno := ISS, sets P.ackno := ISR * receiving retransmitted Request: dccp_check_req() overrides ISR := P.seqno * answering retransmitted Request: dccp_make_response() sets ISS += 1, otherwise as per first Response * completing the handshake: succeeds in dccp_check_req() for the first Ack where P.ackno == ISS (P.seqno is not tested) * creating child socket: ISS, ISR are copied from the request_sock This solution will succeed whenever the server can receive the Request and the subsequent Ack in succession, without retransmissions. If there is packet loss, the client needs to retransmit until this condition succeeds; it will otherwise eventually give up. Adding further fields to the request_sock could increase the robustness a bit, in that it would make possible to let a reordered Ack (from a retransmitted Response) pass. The argument against such a solution is that if the packet loss is not persistent and an Ack gets through, why not wait for the one answering the original response: if the loss is persistent, it is probably better to not start the connection in the first place. Long story short: the present design (by Arnaldo) is simple and will likely work just as well as a more complicated solution. As a consequence, {A,S}W{L,H} are not needed until the moment the request_sock is cloned into the accept queue. At that stage feature negotiation has completed, so that the values for the local and remote Sequence Window feature (7.5.2) are known, i.e. we are now in a better position to compute {A,S}W{L,H}. 2. Client sequence number checks during initial handshake --------------------------------------------------------- Until entering PARTOPEN the client does not need the adjustments, since it constrains the Ack window to the packet it sent. * sending first Request: dccp_v{4,6}_connect() choose ISS, dccp_connect() then sets GAR := ISS (as per 8.5), dccp_transmit_skb() (with the previous bug fix) sets GSS := ISS, AWL := ISS, AWH := GSS * n-th retransmitted Request (with previous patch): dccp_retransmit_skb() via timer calls dccp_transmit_skb(), which sets GSS := ISS+n and then AWL := ISS, AWH := ISS+n * receiving any Response: dccp_rcv_request_sent_state_process() -- accepts packet if AWL <= P.ackno <= AWH; -- sets GSR = ISR = P.seqno * sending the Ack completing the handshake: dccp_send_ack() calls dccp_transmit_skb(), which sets GSS += 1 and AWL := ISS, AWH := GSS Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
* dccp ccid-2: Phase out the use of boolean Ack Vector sysctlGerrit Renker2008-09-041-9/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This removes the use of the sysctl and the minisock variable for the Send Ack Vector feature, which is now handled fully dynamically via feature negotiation; i.e. when CCID2 is enabled, Ack Vectors are automatically enabled (as per RFC 4341, 4.). Using a sysctl in parallel to this implementation would open the door to crashes, since much of the code relies on tests of the boolean minisock / sysctl variable. Thus, this patch replaces all tests of type if (dccp_msk(sk)->dccpms_send_ack_vector) /* ... */ with if (dp->dccps_hc_rx_ackvec != NULL) /* ... */ The dccps_hc_rx_ackvec is allocated by the dccp_hdlr_ackvec() when feature negotiation concluded that Ack Vectors are to be used on the half-connection. Otherwise, it is NULL (due to dccp_init_sock/dccp_create_openreq_child), so that the test is a valid one. The activation handler for Ack Vectors is called as soon as the feature negotiation has concluded at the * server when the Ack marking the transition RESPOND => OPEN arrives; * client after it has sent its ACK, marking the transition REQUEST => PARTOPEN. Adding the sequence number of the Response packet to the Ack Vector has been removed, since (a) connection establishment implies that the Response has been received; (b) the CCIDs only look at packets received in the (PART)OPEN state, i.e. this entry will always be ignored; (c) it can not be used for anything useful - to detect loss for instance, only packets received after the loss can serve as pseudo-dupacks. Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk> Acked-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
* dccp: Integration of dynamic feature activation - part 3 (client side)Gerrit Renker2008-09-041-4/+26
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | This integrates feature-activation in the client, with these details: 1. When dccp_parse_options() fails, the reset code is already set, request_sent _state_process() currently overrides this with `Packet Error', which is not intended - so changed to use the reset code set in dccp_parse_options(); 2. There was a FIXME to change the error code when dccp_ackvec_add() fails. I have looked this up and found that: * the check whether ackno < ISN is already made earlier, * this Response is likely the 1st packet with an Ackno that the client gets, * so when dccp_ackvec_add() fails, the reason is likely not a packet error. 3. When feature negotiation fails, the socket should be marked as not usable, so that the application is notified that an error occurs. This is achieved by a new label, which uses an error code of `Aborted' and which sets the socket state to CLOSED, as well as sk_err. 4. Avoids parsing the Ack twice in Respond state by not doing option processing again in dccp_rcv_respond_partopen_state_process (as option processing has already been done on the request_sock in dccp_check_req). Since this addresses congestion-control initialisation, a corresponding FIXME has been removed. Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk> Acked-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
* dccp: Per-socket initialisation of feature negotiationGerrit Renker2008-09-041-2/+0
| | | | | | | | | | | | This provides feature-negotiation initialisation for both DCCP sockets and DCCP request_sockets, to support feature negotiation during connection setup. It also resolves a FIXME regarding the congestion control initialisation. Thanks to Wei Yongjun for help with the IPv6 side of this patch. Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk> Acked-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
* dccp: Always generate a Reset in response to option errorsWei Yongjun2008-09-041-2/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | RFC4340 states that if a packet is received with an option error (such as a Mandatory Option as the last byte of the option list), the endpoint should repond with a Reset. In the LISTEN and RESPOND states, the endpoint correctly reponds with Reset, while in the REQUEST/OPEN states, packets with option errors are just ignored. The packet sequence is as follows: Case 1: Endpoint A Endpoint B (CLOSED) (CLOSED) <---------------- REQUEST RESPONSE -----------------> (*1) (with invalid option) <---------------- RESET (with Reset Code 5, "Option Error") (*1) currently just ignored, no Reset is sent Case 2: Endpoint A Endpoint B (OPEN) (OPEN) DATA-ACK -----------------> (*2) (with invalid option) <---------------- RESET (with Reset Code 5, "Option Error") (*2) currently just ignored, no Reset is sent This patch fixes the problem, by generating a Reset instead of silently ignoring option errors. Signed-off-by: Wei Yongjun <yjwei@cn.fujitsu.com> Acked-by: Arnaldo Carvalho de Melo <acme@redhat.com> Acked-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
* dccp: Fix panic caused by too early termination of retransmission mechanismGerrit Renker2008-08-181-6/+6
| | | | | | | | | | | | | | | | | | | | | | | | Thanks is due to Wei Yongjun for the detailed analysis and description of this bug at http://marc.info/?l=dccp&m=121739364909199&w=2 The problem is that invalid packets received by a client in state REQUEST cause the retransmission timer for the DCCP-Request to be reset. This includes freeing the Request-skb ( in dccp_rcv_request_sent_state_process() ). As a consequence, * the arrival of further packets cause a double-free, triggering a panic(), * the connection then may hang, since further retransmissions are blocked. This patch changes the order of statements so that the retransmission timer is reset, and the pending Request freed, only if a valid Response has arrived (or the number of sysctl-retries has been exhausted). Further changes: ---------------- To be on the safe side, replaced __kfree_skb with kfree_skb so that if due to unexpected circumstances the sk_send_head is NULL the WARN_ON is used instead. Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk> Signed-off-by: David S. Miller <davem@davemloft.net>
* net: convert BUG_TRAP to generic WARN_ONIlpo Järvinen2008-07-251-1/+1
| | | | | | | | | | | | | | Removes legacy reinvent-the-wheel type thing. The generic machinery integrates much better to automated debugging aids such as kerneloops.org (and others), and is unambiguous due to better naming. Non-intuively BUG_TRAP() is actually equal to WARN_ON() rather than BUG_ON() though some might actually be promoted to BUG_ON() but I left that to future. I could make at least one BUILD_BUG_ON conversion. Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi> Signed-off-by: David S. Miller <davem@davemloft.net>
* [DCCP]: Allow to parse options on Request SocketsGerrit Renker2008-01-281-3/+3
| | | | | | | | | | | | | | | | The option parsing code currently only parses on full sk's. This causes a problem for options sent during the initial handshake (in particular timestamps and feature-negotiation options). Therefore, this patch extends the option parsing code with an additional argument for request_socks: if it is non-NULL, options are parsed on the request socket, otherwise the normal path (parsing on the sk) is used. Subsequent patches, which implement feature negotiation during connection setup, make use of this facility. 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>
* [DCCP]: Perform SHUT_RD and SHUT_WR on receiving closeGerrit Renker2008-01-281-7/+15
| | | | | | | | | | | | | | | | | | | | This patch performs two changes: 1) Close the write-end in addition to the read-end when a fin-like segment (Close or CloseReq) is received by DCCP. This accounts for the fact that DCCP, in contrast to TCP, does not have a half-close. RFC 4340 says in this respect that when a fin-like segment has been sent there is no guarantee at all that any further data will be processed. Thus this patch performs SHUT_WR in addition to the SHUT_RD when a fin-like segment is encountered. 2) Minor change: I noted that code appears twice in different places and think it makes sense to put this into a self-contained function (dccp_enqueue()). 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>
* [DCCP]: Remove duplicate test for CloseReqGerrit Renker2008-01-281-4/+2
| | | | | | | | | | | | | | | | | This removes a redundant test for unexpected packet types. In dccp_rcv_state_process it is tested twice whether a DCCP-server has received a CloseReq (Step 7): * first in the combined if-statement, * then in the call to dccp_rcv_closereq(). The latter is necesssary since dccp_rcv_closereq() is also called from __dccp_rcv_established(). This patch removes the duplicate test. 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>
* [DCCP]: Integrate state transitions for passive-closeGerrit Renker2008-01-281-15/+73
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This adds the necessary state transitions for the two forms of passive-close * PASSIVE_CLOSE - which is entered when a host receives a Close; * PASSIVE_CLOSEREQ - which is entered when a client receives a CloseReq. Here is a detailed account of what the patch does in each state. 1) Receiving CloseReq The pseudo-code in 8.5 says: Step 13: Process CloseReq If P.type == CloseReq and S.state < CLOSEREQ, Generate Close S.state := CLOSING Set CLOSING timer. This means we need to address what to do in CLOSED, LISTEN, REQUEST, RESPOND, PARTOPEN, and OPEN. * CLOSED: silently ignore - it may be a late or duplicate CloseReq; * LISTEN/RESPOND: will not appear, since Step 7 is performed first (we know we are the client); * REQUEST: perform Step 13 directly (no need to enqueue packet); * OPEN/PARTOPEN: enter PASSIVE_CLOSEREQ so that the application has a chance to process unread data. When already in PASSIVE_CLOSEREQ, no second CloseReq is enqueued. In any other state, the CloseReq is ignored. I think that this offers some robustness against rare and pathological cases: e.g. a simultaneous close where the client sends a Close and the server a CloseReq. The client will then be retransmitting its Close until it gets the Reset, so ignoring the CloseReq while in state CLOSING is sane. 2) Receiving Close The code below from 8.5 is unconditional. Step 14: Process Close If P.type == Close, Generate Reset(Closed) Tear down connection Drop packet and return Thus we need to consider all states: * CLOSED: silently ignore, since this can happen when a retransmitted or late Close arrives; * LISTEN: dccp_rcv_state_process() will generate a Reset ("No Connection"); * REQUEST: perform Step 14 directly (no need to enqueue packet); * RESPOND: dccp_check_req() will generate a Reset ("Packet Error") -- left it at that; * OPEN/PARTOPEN: enter PASSIVE_CLOSE so that application has a chance to process unread data; * CLOSEREQ: server performed active-close -- perform Step 14; * CLOSING: simultaneous-close: use a tie-breaker to avoid message ping-pong (see comment); * PASSIVE_CLOSEREQ: ignore - the peer has a bug (sending first a CloseReq and now a Close); * TIMEWAIT: packet is ignored. Note that the condition of receiving a packet in state CLOSED here is different from the condition "there is no socket for such a connection": the socket still exists, but its state indicates it is unusable. Last, dccp_finish_passive_close sets either DCCP_CLOSED or DCCP_CLOSING = TCP_CLOSING, so that sk_stream_wait_close() will wait for the final Reset (which will trigger CLOSING => CLOSED). 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>
* [NET]: Name magic constants in sock_wake_async()Pavel Emelyanov2008-01-281-4/+4
| | | | | | | | | | | | | | | | | | The sock_wake_async() performs a bit different actions depending on "how" argument. Unfortunately this argument ony has numerical magic values. I propose to give names to their constants to help people reading this function callers understand what's going on without looking into this function all the time. I suppose this is 2.6.25 material, but if it's not (or the naming seems poor/bad/awful), I can rework it against the current net-2.6 tree. Signed-off-by: Pavel Emelyanov <xemul@openvz.org> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
* [DCCP]: Honour and make use of shutdown option set by userGerrit Renker2008-01-281-7/+20
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
* [DCCP]: Convert Reset code into socket error numberGerrit Renker2007-10-241-9/+39
| | | | | | | | | | | | | | | | | | | | | | | | | | 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>
* [DCCP]: fix link error with !CONFIG_SYSCTLIngo Molnar2007-10-171-0/+3
| | | | | | | | | | | | | | | | | | | | 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>
* [DCCP]: Rate-limit DCCP-SyncsGerrit Renker2007-10-101-9/+20
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
* [DCCP]: Send Reset upon Sync in state REQUESTGerrit Renker2007-10-101-5/+3
| | | | | | | | | | | | | | | | | | 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>
* [DCCP]: Fix Reset/Sync-Flood BugGerrit Renker2007-10-101-3/+11
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
* [DCCP]: Shorten variable names in dccp_check_seqnoGerrit Renker2007-10-101-23/+17
| | | | | | | | | | | | | | | 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>
* [DCCP]: Simplify interface of dccp_sample_rttGerrit Renker2007-10-101-29/+15
| | | | | | | | | | | | | | | | | | | 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>
* [DCCP]: Convert dccp_sample_rtt to ktime_tArnaldo Carvalho de Melo2007-10-101-13/+10
| | | | | Signed-off-by: Arnaldo Carvalho de Melo <acme@ghostprotocols.net> Signed-off-by: David S. Miller <davem@davemloft.net>
* [DCCP]: Sample RTT from SYN exchangeGerrit Renker2007-04-251-0/+8
| | | | Function:
* [DCCP]: Provide function for RTT samplingGerrit Renker2007-04-251-0/+40
| | | | | | | | | | | | | | A recurring problem, in particular in the CCID code, is that RTT samples from packets with timestamp echo and elapsed time options need to be taken. This service is provided via a new function dccp_sample_rtt in this patch. Furthermore, to protect against `insane' RTT samples, the sampled value is bounded between 100 microseconds and 4 seconds - for which u32 is sufficient. 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>
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