dccp: Initialisation framework for feature negotiation
This initialises feature negotiation from two tables, which are initialised from sysctls. As a novel feature, specifics of the implementation (e.g. currently short seqnos and ECN are not supported) are advertised for robustness. Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk> Acked-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
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@ -369,28 +369,9 @@ static inline unsigned int dccp_hdr_len(const struct sk_buff *skb)
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* Will be used to pass the state from dccp_request_sock to dccp_sock.
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*
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* @dccpms_sequence_window - Sequence Window Feature (section 7.5.2)
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* @dccpms_pending - List of features being negotiated
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* @dccpms_conf -
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*/
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struct dccp_minisock {
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__u64 dccpms_sequence_window;
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struct list_head dccpms_pending;
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struct list_head dccpms_conf;
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};
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struct dccp_opt_conf {
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__u8 *dccpoc_val;
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__u8 dccpoc_len;
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};
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struct dccp_opt_pend {
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struct list_head dccpop_node;
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__u8 dccpop_type;
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__u8 dccpop_feat;
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__u8 *dccpop_val;
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__u8 dccpop_len;
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int dccpop_conf;
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struct dccp_opt_conf *dccpop_sc;
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};
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extern void dccp_minisock_init(struct dccp_minisock *dmsk);
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@ -1110,24 +1110,70 @@ int dccp_feat_parse_options(struct sock *sk, struct dccp_request_sock *dreq,
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return 0; /* ignore FN options in all other states */
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}
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/**
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* dccp_feat_init - Seed feature negotiation with host-specific defaults
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* This initialises global defaults, depending on the value of the sysctls.
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* These can later be overridden by registering changes via setsockopt calls.
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* The last link in the chain is finalise_settings, to make sure that between
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* here and the start of actual feature negotiation no inconsistencies enter.
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*
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* All features not appearing below use either defaults or are otherwise
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* later adjusted through dccp_feat_finalise_settings().
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*/
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int dccp_feat_init(struct sock *sk)
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{
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struct dccp_sock *dp = dccp_sk(sk);
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struct dccp_minisock *dmsk = dccp_msk(sk);
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struct list_head *fn = &dccp_sk(sk)->dccps_featneg;
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u8 on = 1, off = 0;
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int rc;
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struct {
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u8 *val;
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u8 len;
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} tx, rx;
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INIT_LIST_HEAD(&dmsk->dccpms_pending); /* XXX no longer used */
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INIT_LIST_HEAD(&dmsk->dccpms_conf); /* XXX no longer used */
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/* Non-negotiable (NN) features */
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rc = __feat_register_nn(fn, DCCPF_SEQUENCE_WINDOW, 0,
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sysctl_dccp_feat_sequence_window);
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if (rc)
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return rc;
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/* Ack ratio */
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rc = __feat_register_nn(&dp->dccps_featneg, DCCPF_ACK_RATIO, 0,
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dp->dccps_l_ack_ratio);
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out:
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/* Server-priority (SP) features */
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/* Advertise that short seqnos are not supported (7.6.1) */
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rc = __feat_register_sp(fn, DCCPF_SHORT_SEQNOS, true, true, &off, 1);
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if (rc)
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return rc;
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/* RFC 4340 12.1: "If a DCCP is not ECN capable, ..." */
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rc = __feat_register_sp(fn, DCCPF_ECN_INCAPABLE, true, true, &on, 1);
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if (rc)
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return rc;
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/*
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* We advertise the available list of CCIDs and reorder according to
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* preferences, to avoid failure resulting from negotiating different
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* singleton values (which always leads to failure).
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* These settings can still (later) be overridden via sockopts.
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*/
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if (ccid_get_builtin_ccids(&tx.val, &tx.len) ||
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ccid_get_builtin_ccids(&rx.val, &rx.len))
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return -ENOBUFS;
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if (!dccp_feat_prefer(sysctl_dccp_feat_tx_ccid, tx.val, tx.len) ||
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!dccp_feat_prefer(sysctl_dccp_feat_rx_ccid, rx.val, rx.len))
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goto free_ccid_lists;
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rc = __feat_register_sp(fn, DCCPF_CCID, true, false, tx.val, tx.len);
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if (rc)
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goto free_ccid_lists;
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rc = __feat_register_sp(fn, DCCPF_CCID, false, false, rx.val, rx.len);
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free_ccid_lists:
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kfree(tx.val);
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kfree(rx.val);
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return rc;
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}
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EXPORT_SYMBOL_GPL(dccp_feat_init);
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int dccp_feat_activate_values(struct sock *sk, struct list_head *fn_list)
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{
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struct dccp_sock *dp = dccp_sk(sk);
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@ -112,13 +112,13 @@ static inline void dccp_feat_debug(const u8 type, const u8 feat, const u8 val)
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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 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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extern int dccp_feat_init(struct sock *sk);
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/*
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* Encoding variable-length options and their maximum length.
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