kernel/git/stable/linux.git/net/dccp/ccids/ccid3.h, branch master

net: Retire DCCP socket.

2025-04-12T01:58:10+00:00

DCCP was orphaned in 2021 by commit 054c4610bd05 ("MAINTAINERS: dccp: move Gerrit Renker to CREDITS"), which noted that the last maintainer had been inactive for five years. In recent years, it has become a playground for syzbot, and most changes to DCCP have been odd bug fixes triggered by syzbot. Apart from that, the only changes have been driven by treewide or networking API updates or adjustments related to TCP. Thus, in 2023, we announced we would remove DCCP in 2025 via commit b144fcaf46d4 ("dccp: Print deprecation notice."). Since then, only one individual has contacted the netdev mailing list. [0] There is ongoing research for Multipath DCCP. The repository is hosted on GitHub [1], and development is not taking place through the upstream community. While the repository is published under the GPLv2 license, the scheduling part remains proprietary, with a LICENSE file [2] stating: "This is not Open Source software." The researcher mentioned a plan to address the licensing issue, upstream the patches, and step up as a maintainer, but there has been no further communication since then. Maintaining DCCP for a decade without any real users has become a burden. Therefore, it's time to remove it. Removing DCCP will also provide significant benefits to TCP. It allows us to freely reorganize the layout of struct inet_connection_sock, which is currently shared with DCCP, and optimize it to reduce the number of cachelines accessed in the TCP fast path. Note that we keep DCCP netfilter modules as requested. [3] Link: https://lore.kernel.org/netdev/20230710182253.81446-1-kuniyu@amazon.com/T/#u #[0] Link: https://github.com/telekom/mp-dccp #[1] Link: https://github.com/telekom/mp-dccp/blob/mpdccp_v03_k5.10/net/dccp/non_gpl_scheduler/LICENSE #[2] Link: https://lore.kernel.org/netdev/Z_VQ0KlCRkqYWXa-@calendula/ #[3] Signed-off-by: Kuniyuki Iwashima Acked-by: Paul Moore (LSM and SELinux) Acked-by: Casey Schaufler Link: https://patch.msgid.link/20250410023921.11307-3-kuniyu@amazon.com Signed-off-by: Jakub Kicinski

dccp: Replace HTTP links with HTTPS ones

2020-07-13T18:54:07+00:00

Rationale: Reduces attack surface on kernel devs opening the links for MITM as HTTPS traffic is much harder to manipulate. Deterministic algorithm: For each file: If not .svg: For each line: If doesn't contain `\bxmlns\b`: For each link, `\bhttp://[^# \t\r\n]*(?:\w|/)`: If neither `\bgnu\.org/license`, nor `\bmozilla\.org/MPL\b`: If both the HTTP and HTTPS versions return 200 OK and serve the same content: Replace HTTP with HTTPS. Signed-off-by: Alexander A. Klimov Signed-off-by: David S. Miller

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 132

2019-05-30T18:25:14+00:00

Based on 1 normalized pattern(s): this program 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 of the license or at your option any later version this program 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 this program if not write to the free software foundation inc 675 mass ave cambridge ma 02139 usa extracted by the scancode license scanner the SPDX license identifier GPL-2.0-or-later has been chosen to replace the boilerplate/reference in 4 file(s). Signed-off-by: Thomas Gleixner Reviewed-by: Richard Fontana Reviewed-by: Kate Stewart Reviewed-by: Allison Randal Cc: linux-spdx@vger.kernel.org Link: https://lkml.kernel.org/r/20190524100843.499675784@linutronix.de Signed-off-by: Greg Kroah-Hartman

net: dccp: Convert timers to use timer_setup()

2017-10-25T03:59:19+00:00

In preparation for unconditionally passing the struct timer_list pointer to all timer callbacks, switch to using the new timer_setup() and from_timer() to pass the timer pointer explicitly. Adds a pointer back to the sock. Cc: Gerrit Renker Cc: "David S. Miller" Cc: Soheil Hassas Yeganeh Cc: Hannes Frederic Sowa Cc: Eric Dumazet Cc: dccp@vger.kernel.org Cc: netdev@vger.kernel.org Signed-off-by: Kees Cook Signed-off-by: David S. Miller

dccp ccid-3: Remove redundant 'options_received' struct

2010-09-21T10:14:26+00:00

The `options_received' struct is redundant, since it re-duplicates the existing `p' and `x_recv' fields. This patch removes the sub-struct and migrates the format conversion operations to ccid3_hc_tx_parse_options(). Signed-off-by: Gerrit Renker

dccp ccid-3: remove dead states

2010-09-21T10:14:26+00:00

This patch is thanks to an investigation by Leandro Sales de Melo and his colleagues. They worked out two state diagrams which highlight the fact that the xxx_TERM states in CCID-3/4 are in fact not necessary. And this can be confirmed by in turn looking at the code: the xxx_TERM states are only ever set in ccid3_hc_{rx,tx}_exit(): when CCID-3 sets the state to xxx_TERM, it is at a time where no more processing should be going on, hence it is not necessary to introduce a dedicated exit state - this is already implied by unloading the CCID. Signed-off-by: Gerrit Renker

dccp ccid-3: Simplify and consolidate tx_parse_options

2010-09-15T10:36:02+00:00

This simplifies and consolidates the TX option-parsing code: 1. The Loss Intervals option is not currently used, so dead code related to this option is removed. I am aware of no plans to support the option, but if someone wants to implement it (e.g. for inter-op tests), it is better to start afresh than having to also update currently unused code. 2. The Loss Event and Receive Rate options have a lot of code in common (both are 32 bit, both have same length etc.), so this is consolidated. 3. The test against GSR is not necessary, because - on first loading CCID3, ccid_new() zeroes out all fields in the socket; - ccid3_hc_tx_packet_recv() treats 0 and ~0U equivalently, due to pinv = opt_recv->ccid3or_loss_event_rate; if (pinv == ~0U || pinv == 0) hctx->p = 0; - as a result, the sequence number field is removed from opt_recv. Signed-off-by: Gerrit Renker

dccp ccid-3: A lower bound for the inter-packet scheduling algorithm

2010-09-15T10:36:01+00:00

This fixes a subtle bug in the calculation of the inter-packet gap and shows that t_delta, as it is currently used, is not needed. The algorithm from RFC 5348, 8.3 below continually computes a send time t_nom, which is initialised with the current time t_now; t_gran = 1E6 / HZ specifies the scheduling granularity, s the packet size, and X the sending rate: t_distance = t_nom - t_now; // in microseconds t_delta = min(t_ipi, t_gran) / 2; // `delta' parameter in microseconds if (t_distance >= t_delta) { reschedule after (t_distance / 1000) milliseconds; } else { t_ipi = s / X; // inter-packet interval in usec t_nom += t_ipi; // compute the next send time send packet now; } Problem: -------- Rescheduling requires a conversion into milliseconds (sk_reset_timer()). The highest jiffy resolution with HZ=1000 is 1 millisecond, so using a higher granularity does not make much sense here. As a consequence, values of t_distance < 1000 are truncated to 0. This issue has so far been resolved by using instead if (t_distance >= t_delta + 1000) reschedule after (t_distance / 1000) milliseconds; This is unnecessarily large, a lower bound is t_delta' = max(t_delta, 1000). And it implies a further simplification: a) when HZ >= 500, then t_delta <= t_gran/2 = 10^6/(2*HZ) <= 1000, so that t_delta' = MAX(1000, t_delta) = 1000 (constant value); b) when HZ < 500, then t_delta = 1/2*MIN(rtt, t_ipi, t_gran) <= t_gran/2, so that 1000 <= t_delta' <= t_gran/2. The maximum error of using a constant t_delta in (b) is less than half a jiffy. Fix: ---- The patch replaces t_delta with a constant, whose value depends on CONFIG_HZ, changing the above algorithm to: if (t_distance >= t_delta') reschedule after (t_distance / 1000) milliseconds; where t_delta' = 10^6/(2*HZ) if HZ < 500, and t_delta' = 1000 otherwise. Signed-off-by: Gerrit Renker

dccp ccid-3: use per-route RTO or TCP RTO as fallback

2010-08-30T20:45:28+00:00

This makes RTAX_RTO_MIN also available to CCID-3, replacing the compile-time RTO lower bound with a per-route tunable value. The original Kconfig option solved the problem that a very low RTT (in the order of HZ) can trigger too frequent and unnecessary reductions of the sending rate. This tunable does not affect the initial RTO value of 2 seconds specified in RFC 5348, section 4.2 and Appendix B. But like the hardcoded Kconfig value, it allows to adapt to network conditions. The same effect as the original Kconfig option of 100ms is now achieved by > ip route replace to unicast 192.168.0.0/24 rto_min 100j dev eth0 (assuming HZ=1000). Signed-off-by: Gerrit Renker Signed-off-by: David S. Miller

ccid: ccid-2/3 code cosmetics

2010-08-24T03:13:29+00:00

This patch collects cosmetics-only changes to separate these from code changes: * update with regard to CodingStyle and whitespace changes, * documentation: - adding/revising comments, - remove CCID-3 RX socket documentation which is either duplicate or refers to fields that no longer exist, * expand embedded tfrc_tx_info struct inline for consistency, removing indirections via #define. Signed-off-by: Gerrit Renker Signed-off-by: David S. Miller