883ca833e5
This patch takes care of initialising and type-checking sysctls
related to feature negotiation. Type checking is important since some
of the sysctls now directly impact the feature-negotiation process.
The sysctls are initialised with the known default values for each
feature. For the type-checking the value constraints from RFC 4340
are used:
* Sequence Window uses the specified Wmin=32, the maximum is ulong (4 bytes),
tested and confirmed that it works up to 4294967295 - for Gbps speed;
* Ack Ratio is between 0 .. 0xffff (2-byte unsigned integer);
* CCIDs are between 0 .. 255;
* request_retries, retries1, retries2 also between 0..255 for good measure;
* tx_qlen is checked to be non-negative;
* sync_ratelimit remains as before.
Notes:
------
1. Die s@sysctl_dccp_feat@sysctl_dccp@g since the sysctls are now in feat.c.
2. As pointed out by Arnaldo, the pattern of type-checking repeats itself in
other places, sometimes with exactly the same kind of definitions (e.g.
"static int zero;"). It may be a good idea (kernel janitors?) to consolidate
type checking. For the sake of keeping the changeset small and in order not
to affect other subsystems, I have not strived to generalise here.
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>
150 lines
5 KiB
C
150 lines
5 KiB
C
#ifndef _DCCP_FEAT_H
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#define _DCCP_FEAT_H
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/*
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* net/dccp/feat.h
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*
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* Feature negotiation for the DCCP protocol (RFC 4340, section 6)
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* Copyright (c) 2008 Gerrit Renker <gerrit@erg.abdn.ac.uk>
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* Copyright (c) 2005 Andrea Bittau <a.bittau@cs.ucl.ac.uk>
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/types.h>
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#include "dccp.h"
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/*
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* Known limit values
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*/
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/* Ack Ratio takes 2-byte integer values (11.3) */
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#define DCCPF_ACK_RATIO_MAX 0xFFFF
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/* Wmin=32 and Wmax=2^46-1 from 7.5.2 */
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#define DCCPF_SEQ_WMIN 32
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#define DCCPF_SEQ_WMAX 0x3FFFFFFFFFFFull
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/* Maximum number of SP values that fit in a single (Confirm) option */
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#define DCCP_FEAT_MAX_SP_VALS (DCCP_SINGLE_OPT_MAXLEN - 2)
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enum dccp_feat_type {
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FEAT_AT_RX = 1, /* located at RX side of half-connection */
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FEAT_AT_TX = 2, /* located at TX side of half-connection */
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FEAT_SP = 4, /* server-priority reconciliation (6.3.1) */
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FEAT_NN = 8, /* non-negotiable reconciliation (6.3.2) */
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FEAT_UNKNOWN = 0xFF /* not understood or invalid feature */
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};
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enum dccp_feat_state {
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FEAT_DEFAULT = 0, /* using default values from 6.4 */
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FEAT_INITIALISING, /* feature is being initialised */
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FEAT_CHANGING, /* Change sent but not confirmed yet */
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FEAT_UNSTABLE, /* local modification in state CHANGING */
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FEAT_STABLE /* both ends (think they) agree */
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};
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/**
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* dccp_feat_val - Container for SP or NN feature values
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* @nn: single NN value
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* @sp.vec: single SP value plus optional preference list
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* @sp.len: length of @sp.vec in bytes
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*/
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typedef union {
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u64 nn;
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struct {
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u8 *vec;
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u8 len;
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} sp;
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} dccp_feat_val;
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/**
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* struct feat_entry - Data structure to perform feature negotiation
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* @val: feature's current value (SP features may have preference list)
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* @state: feature's current state
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* @feat_num: one of %dccp_feature_numbers
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* @needs_mandatory: whether Mandatory options should be sent
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* @needs_confirm: whether to send a Confirm instead of a Change
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* @empty_confirm: whether to send an empty Confirm (depends on @needs_confirm)
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* @is_local: feature location (1) or feature-remote (0)
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* @node: list pointers, entries arranged in FIFO order
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*/
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struct dccp_feat_entry {
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dccp_feat_val val;
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enum dccp_feat_state state:8;
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u8 feat_num;
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bool needs_mandatory,
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needs_confirm,
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empty_confirm,
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is_local;
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struct list_head node;
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};
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static inline u8 dccp_feat_genopt(struct dccp_feat_entry *entry)
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{
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if (entry->needs_confirm)
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return entry->is_local ? DCCPO_CONFIRM_L : DCCPO_CONFIRM_R;
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return entry->is_local ? DCCPO_CHANGE_L : DCCPO_CHANGE_R;
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}
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/**
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* struct ccid_dependency - Track changes resulting from choosing a CCID
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* @dependent_feat: one of %dccp_feature_numbers
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* @is_local: local (1) or remote (0) @dependent_feat
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* @is_mandatory: whether presence of @dependent_feat is mission-critical or not
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* @val: corresponding default value for @dependent_feat (u8 is sufficient here)
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*/
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struct ccid_dependency {
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u8 dependent_feat;
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bool is_local:1,
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is_mandatory:1;
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u8 val;
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};
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/*
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* Sysctls to seed defaults for feature negotiation
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*/
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extern unsigned long sysctl_dccp_sequence_window;
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extern int sysctl_dccp_rx_ccid;
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extern int sysctl_dccp_tx_ccid;
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#ifdef CONFIG_IP_DCCP_DEBUG
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extern const char *dccp_feat_typename(const u8 type);
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extern const char *dccp_feat_name(const u8 feat);
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static inline void dccp_feat_debug(const u8 type, const u8 feat, const u8 val)
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{
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dccp_pr_debug("%s(%s (%d), %d)\n", dccp_feat_typename(type),
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dccp_feat_name(feat), feat, val);
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}
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#else
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#define dccp_feat_debug(type, feat, val)
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#endif /* CONFIG_IP_DCCP_DEBUG */
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extern int dccp_feat_init(struct sock *sk);
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extern void dccp_feat_initialise_sysctls(void);
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extern int dccp_feat_register_sp(struct sock *sk, u8 feat, u8 is_local,
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u8 const *list, u8 len);
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extern int dccp_feat_register_nn(struct sock *sk, u8 feat, u64 val);
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extern int dccp_feat_parse_options(struct sock *, struct dccp_request_sock *,
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u8 mand, u8 opt, u8 feat, u8 *val, u8 len);
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extern int dccp_feat_clone_list(struct list_head const *, struct list_head *);
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/*
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* Encoding variable-length options and their maximum length.
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*
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* This affects NN options (SP options are all u8) and other variable-length
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* options (see table 3 in RFC 4340). The limit is currently given the Sequence
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* Window NN value (sec. 7.5.2) and the NDP count (sec. 7.7) option, all other
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* options consume less than 6 bytes (timestamps are 4 bytes).
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* When updating this constant (e.g. due to new internet drafts / RFCs), make
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* sure that you also update all code which refers to it.
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*/
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#define DCCP_OPTVAL_MAXLEN 6
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extern void dccp_encode_value_var(const u64 value, u8 *to, const u8 len);
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extern u64 dccp_decode_value_var(const u8 *bf, const u8 len);
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extern int dccp_insert_option_mandatory(struct sk_buff *skb);
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extern int dccp_insert_fn_opt(struct sk_buff *skb, u8 type, u8 feat,
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u8 *val, u8 len, bool repeat_first);
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#endif /* _DCCP_FEAT_H */
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