linux/net/dccp/feat.c
Gerrit Renker 4098dce5be dccp: Remove manual influence on NDP Count feature
Updating the NDP count feature is handled automatically now:
 * for CCID-2 it is disabled, since the code does not use NDP counts;
 * for CCID-3 it is enabled, as NDP counts are used to determine loss lengths.

Allowing the user to change NDP values leads to unpredictable and failing
behaviour, since it is then possible to disable NDP counts even when they
are needed (e.g. in CCID-3).

This means that only those user settings are sensible that agree with the
values for Send NDP Count implied by the choice of CCID. But those settings
are already activated by the feature negotiation (CCID dependency tracking),
hence this form of support is redundant.

At startup the initialisation of the NDP count feature uses the default
value of 0, which is done implicitly by the zeroing-out of the socket when
it is allocated. If the choice of CCID or feature negotiation enables NDP
count, this will then be updated via the NDP activation handler.

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>
2008-12-08 01:18:37 -08:00

1245 lines
37 KiB
C

/*
* net/dccp/feat.c
*
* Feature negotiation for the DCCP protocol (RFC 4340, section 6)
*
* Copyright (c) 2008 Gerrit Renker <gerrit@erg.abdn.ac.uk>
* Rewrote from scratch, some bits from earlier code by
* Copyright (c) 2005 Andrea Bittau <a.bittau@cs.ucl.ac.uk>
*
*
* ASSUMPTIONS
* -----------
* o Feature negotiation is coordinated with connection setup (as in TCP), wild
* changes of parameters of an established connection are not supported.
* o All currently known SP features have 1-byte quantities. If in the future
* extensions of RFCs 4340..42 define features with item lengths larger than
* one byte, a feature-specific extension of the code will be required.
*
* 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.
*/
#include <linux/module.h>
#include "ccid.h"
#include "feat.h"
/*
* Feature activation handlers.
*
* These all use an u64 argument, to provide enough room for NN/SP features. At
* this stage the negotiated values have been checked to be within their range.
*/
static int dccp_hdlr_ccid(struct sock *sk, u64 ccid, bool rx)
{
struct dccp_sock *dp = dccp_sk(sk);
struct ccid *new_ccid = ccid_new(ccid, sk, rx, gfp_any());
if (new_ccid == NULL)
return -ENOMEM;
if (rx) {
ccid_hc_rx_delete(dp->dccps_hc_rx_ccid, sk);
dp->dccps_hc_rx_ccid = new_ccid;
} else {
ccid_hc_tx_delete(dp->dccps_hc_tx_ccid, sk);
dp->dccps_hc_tx_ccid = new_ccid;
}
return 0;
}
static int dccp_hdlr_seq_win(struct sock *sk, u64 seq_win, bool rx)
{
if (!rx)
dccp_msk(sk)->dccpms_sequence_window = seq_win;
return 0;
}
static int dccp_hdlr_ack_ratio(struct sock *sk, u64 ratio, bool rx)
{
if (rx)
dccp_sk(sk)->dccps_r_ack_ratio = ratio;
else
dccp_sk(sk)->dccps_l_ack_ratio = ratio;
return 0;
}
static int dccp_hdlr_ackvec(struct sock *sk, u64 enable, bool rx)
{
struct dccp_sock *dp = dccp_sk(sk);
if (rx) {
if (enable && dp->dccps_hc_rx_ackvec == NULL) {
dp->dccps_hc_rx_ackvec = dccp_ackvec_alloc(gfp_any());
if (dp->dccps_hc_rx_ackvec == NULL)
return -ENOMEM;
} else if (!enable) {
dccp_ackvec_free(dp->dccps_hc_rx_ackvec);
dp->dccps_hc_rx_ackvec = NULL;
}
}
return 0;
}
static int dccp_hdlr_ndp(struct sock *sk, u64 enable, bool rx)
{
if (!rx)
dccp_sk(sk)->dccps_send_ndp_count = (enable > 0);
return 0;
}
/*
* Minimum Checksum Coverage is located at the RX side (9.2.1). This means that
* `rx' holds when the sending peer informs about his partial coverage via a
* ChangeR() option. In the other case, we are the sender and the receiver
* announces its coverage via ChangeL() options. The policy here is to honour
* such communication by enabling the corresponding partial coverage - but only
* if it has not been set manually before; the warning here means that all
* packets will be dropped.
*/
static int dccp_hdlr_min_cscov(struct sock *sk, u64 cscov, bool rx)
{
struct dccp_sock *dp = dccp_sk(sk);
if (rx)
dp->dccps_pcrlen = cscov;
else {
if (dp->dccps_pcslen == 0)
dp->dccps_pcslen = cscov;
else if (cscov > dp->dccps_pcslen)
DCCP_WARN("CsCov %u too small, peer requires >= %u\n",
dp->dccps_pcslen, (u8)cscov);
}
return 0;
}
static const struct {
u8 feat_num; /* DCCPF_xxx */
enum dccp_feat_type rxtx; /* RX or TX */
enum dccp_feat_type reconciliation; /* SP or NN */
u8 default_value; /* as in 6.4 */
int (*activation_hdlr)(struct sock *sk, u64 val, bool rx);
/*
* Lookup table for location and type of features (from RFC 4340/4342)
* +--------------------------+----+-----+----+----+---------+-----------+
* | Feature | Location | Reconc. | Initial | Section |
* | | RX | TX | SP | NN | Value | Reference |
* +--------------------------+----+-----+----+----+---------+-----------+
* | DCCPF_CCID | | X | X | | 2 | 10 |
* | DCCPF_SHORT_SEQNOS | | X | X | | 0 | 7.6.1 |
* | DCCPF_SEQUENCE_WINDOW | | X | | X | 100 | 7.5.2 |
* | DCCPF_ECN_INCAPABLE | X | | X | | 0 | 12.1 |
* | DCCPF_ACK_RATIO | | X | | X | 2 | 11.3 |
* | DCCPF_SEND_ACK_VECTOR | X | | X | | 0 | 11.5 |
* | DCCPF_SEND_NDP_COUNT | | X | X | | 0 | 7.7.2 |
* | DCCPF_MIN_CSUM_COVER | X | | X | | 0 | 9.2.1 |
* | DCCPF_DATA_CHECKSUM | X | | X | | 0 | 9.3.1 |
* | DCCPF_SEND_LEV_RATE | X | | X | | 0 | 4342/8.4 |
* +--------------------------+----+-----+----+----+---------+-----------+
*/
} dccp_feat_table[] = {
{ DCCPF_CCID, FEAT_AT_TX, FEAT_SP, 2, dccp_hdlr_ccid },
{ DCCPF_SHORT_SEQNOS, FEAT_AT_TX, FEAT_SP, 0, NULL },
{ DCCPF_SEQUENCE_WINDOW, FEAT_AT_TX, FEAT_NN, 100, dccp_hdlr_seq_win },
{ DCCPF_ECN_INCAPABLE, FEAT_AT_RX, FEAT_SP, 0, NULL },
{ DCCPF_ACK_RATIO, FEAT_AT_TX, FEAT_NN, 2, dccp_hdlr_ack_ratio},
{ DCCPF_SEND_ACK_VECTOR, FEAT_AT_RX, FEAT_SP, 0, dccp_hdlr_ackvec },
{ DCCPF_SEND_NDP_COUNT, FEAT_AT_TX, FEAT_SP, 0, dccp_hdlr_ndp },
{ DCCPF_MIN_CSUM_COVER, FEAT_AT_RX, FEAT_SP, 0, dccp_hdlr_min_cscov},
{ DCCPF_DATA_CHECKSUM, FEAT_AT_RX, FEAT_SP, 0, NULL },
{ DCCPF_SEND_LEV_RATE, FEAT_AT_RX, FEAT_SP, 0, NULL },
};
#define DCCP_FEAT_SUPPORTED_MAX ARRAY_SIZE(dccp_feat_table)
/**
* dccp_feat_index - Hash function to map feature number into array position
* Returns consecutive array index or -1 if the feature is not understood.
*/
static int dccp_feat_index(u8 feat_num)
{
/* The first 9 entries are occupied by the types from RFC 4340, 6.4 */
if (feat_num > DCCPF_RESERVED && feat_num <= DCCPF_DATA_CHECKSUM)
return feat_num - 1;
/*
* Other features: add cases for new feature types here after adding
* them to the above table.
*/
switch (feat_num) {
case DCCPF_SEND_LEV_RATE:
return DCCP_FEAT_SUPPORTED_MAX - 1;
}
return -1;
}
static u8 dccp_feat_type(u8 feat_num)
{
int idx = dccp_feat_index(feat_num);
if (idx < 0)
return FEAT_UNKNOWN;
return dccp_feat_table[idx].reconciliation;
}
static int dccp_feat_default_value(u8 feat_num)
{
int idx = dccp_feat_index(feat_num);
/*
* There are no default values for unknown features, so encountering a
* negative index here indicates a serious problem somewhere else.
*/
DCCP_BUG_ON(idx < 0);
return idx < 0 ? 0 : dccp_feat_table[idx].default_value;
}
static int __dccp_feat_activate(struct sock *sk, const int idx,
const bool is_local, dccp_feat_val const *fval)
{
bool rx;
u64 val;
if (idx < 0 || idx >= DCCP_FEAT_SUPPORTED_MAX)
return -1;
if (dccp_feat_table[idx].activation_hdlr == NULL)
return 0;
if (fval == NULL) {
val = dccp_feat_table[idx].default_value;
} else if (dccp_feat_table[idx].reconciliation == FEAT_SP) {
if (fval->sp.vec == NULL) {
/*
* This can happen when an empty Confirm is sent
* for an SP (i.e. known) feature. In this case
* we would be using the default anyway.
*/
DCCP_CRIT("Feature #%d undefined: using default", idx);
val = dccp_feat_table[idx].default_value;
} else {
val = fval->sp.vec[0];
}
} else {
val = fval->nn;
}
/* Location is RX if this is a local-RX or remote-TX feature */
rx = (is_local == (dccp_feat_table[idx].rxtx == FEAT_AT_RX));
return dccp_feat_table[idx].activation_hdlr(sk, val, rx);
}
/* Test for "Req'd" feature (RFC 4340, 6.4) */
static inline int dccp_feat_must_be_understood(u8 feat_num)
{
return feat_num == DCCPF_CCID || feat_num == DCCPF_SHORT_SEQNOS ||
feat_num == DCCPF_SEQUENCE_WINDOW;
}
/* copy constructor, fval must not already contain allocated memory */
static int dccp_feat_clone_sp_val(dccp_feat_val *fval, u8 const *val, u8 len)
{
fval->sp.len = len;
if (fval->sp.len > 0) {
fval->sp.vec = kmemdup(val, len, gfp_any());
if (fval->sp.vec == NULL) {
fval->sp.len = 0;
return -ENOBUFS;
}
}
return 0;
}
static void dccp_feat_val_destructor(u8 feat_num, dccp_feat_val *val)
{
if (unlikely(val == NULL))
return;
if (dccp_feat_type(feat_num) == FEAT_SP)
kfree(val->sp.vec);
memset(val, 0, sizeof(*val));
}
static struct dccp_feat_entry *
dccp_feat_clone_entry(struct dccp_feat_entry const *original)
{
struct dccp_feat_entry *new;
u8 type = dccp_feat_type(original->feat_num);
if (type == FEAT_UNKNOWN)
return NULL;
new = kmemdup(original, sizeof(struct dccp_feat_entry), gfp_any());
if (new == NULL)
return NULL;
if (type == FEAT_SP && dccp_feat_clone_sp_val(&new->val,
original->val.sp.vec,
original->val.sp.len)) {
kfree(new);
return NULL;
}
return new;
}
static void dccp_feat_entry_destructor(struct dccp_feat_entry *entry)
{
if (entry != NULL) {
dccp_feat_val_destructor(entry->feat_num, &entry->val);
kfree(entry);
}
}
/*
* List management functions
*
* Feature negotiation lists rely on and maintain the following invariants:
* - each feat_num in the list is known, i.e. we know its type and default value
* - each feat_num/is_local combination is unique (old entries are overwritten)
* - SP values are always freshly allocated
* - list is sorted in increasing order of feature number (faster lookup)
*/
static struct dccp_feat_entry *dccp_feat_list_lookup(struct list_head *fn_list,
u8 feat_num, bool is_local)
{
struct dccp_feat_entry *entry;
list_for_each_entry(entry, fn_list, node) {
if (entry->feat_num == feat_num && entry->is_local == is_local)
return entry;
else if (entry->feat_num > feat_num)
break;
}
return NULL;
}
/**
* dccp_feat_entry_new - Central list update routine (called by all others)
* @head: list to add to
* @feat: feature number
* @local: whether the local (1) or remote feature with number @feat is meant
* This is the only constructor and serves to ensure the above invariants.
*/
static struct dccp_feat_entry *
dccp_feat_entry_new(struct list_head *head, u8 feat, bool local)
{
struct dccp_feat_entry *entry;
list_for_each_entry(entry, head, node)
if (entry->feat_num == feat && entry->is_local == local) {
dccp_feat_val_destructor(entry->feat_num, &entry->val);
return entry;
} else if (entry->feat_num > feat) {
head = &entry->node;
break;
}
entry = kmalloc(sizeof(*entry), gfp_any());
if (entry != NULL) {
entry->feat_num = feat;
entry->is_local = local;
list_add_tail(&entry->node, head);
}
return entry;
}
/**
* dccp_feat_push_change - Add/overwrite a Change option in the list
* @fn_list: feature-negotiation list to update
* @feat: one of %dccp_feature_numbers
* @local: whether local (1) or remote (0) @feat_num is meant
* @needs_mandatory: whether to use Mandatory feature negotiation options
* @fval: pointer to NN/SP value to be inserted (will be copied)
*/
static int dccp_feat_push_change(struct list_head *fn_list, u8 feat, u8 local,
u8 mandatory, dccp_feat_val *fval)
{
struct dccp_feat_entry *new = dccp_feat_entry_new(fn_list, feat, local);
if (new == NULL)
return -ENOMEM;
new->feat_num = feat;
new->is_local = local;
new->state = FEAT_INITIALISING;
new->needs_confirm = 0;
new->empty_confirm = 0;
new->val = *fval;
new->needs_mandatory = mandatory;
return 0;
}
/**
* dccp_feat_push_confirm - Add a Confirm entry to the FN list
* @fn_list: feature-negotiation list to add to
* @feat: one of %dccp_feature_numbers
* @local: whether local (1) or remote (0) @feat_num is being confirmed
* @fval: pointer to NN/SP value to be inserted or NULL
* Returns 0 on success, a Reset code for further processing otherwise.
*/
static int dccp_feat_push_confirm(struct list_head *fn_list, u8 feat, u8 local,
dccp_feat_val *fval)
{
struct dccp_feat_entry *new = dccp_feat_entry_new(fn_list, feat, local);
if (new == NULL)
return DCCP_RESET_CODE_TOO_BUSY;
new->feat_num = feat;
new->is_local = local;
new->state = FEAT_STABLE; /* transition in 6.6.2 */
new->needs_confirm = 1;
new->empty_confirm = (fval == NULL);
new->val.nn = 0; /* zeroes the whole structure */
if (!new->empty_confirm)
new->val = *fval;
new->needs_mandatory = 0;
return 0;
}
static int dccp_push_empty_confirm(struct list_head *fn_list, u8 feat, u8 local)
{
return dccp_feat_push_confirm(fn_list, feat, local, NULL);
}
static inline void dccp_feat_list_pop(struct dccp_feat_entry *entry)
{
list_del(&entry->node);
dccp_feat_entry_destructor(entry);
}
void dccp_feat_list_purge(struct list_head *fn_list)
{
struct dccp_feat_entry *entry, *next;
list_for_each_entry_safe(entry, next, fn_list, node)
dccp_feat_entry_destructor(entry);
INIT_LIST_HEAD(fn_list);
}
EXPORT_SYMBOL_GPL(dccp_feat_list_purge);
/* generate @to as full clone of @from - @to must not contain any nodes */
int dccp_feat_clone_list(struct list_head const *from, struct list_head *to)
{
struct dccp_feat_entry *entry, *new;
INIT_LIST_HEAD(to);
list_for_each_entry(entry, from, node) {
new = dccp_feat_clone_entry(entry);
if (new == NULL)
goto cloning_failed;
list_add_tail(&new->node, to);
}
return 0;
cloning_failed:
dccp_feat_list_purge(to);
return -ENOMEM;
}
/**
* dccp_feat_valid_nn_length - Enforce length constraints on NN options
* Length is between 0 and %DCCP_OPTVAL_MAXLEN. Used for outgoing packets only,
* incoming options are accepted as long as their values are valid.
*/
static u8 dccp_feat_valid_nn_length(u8 feat_num)
{
if (feat_num == DCCPF_ACK_RATIO) /* RFC 4340, 11.3 and 6.6.8 */
return 2;
if (feat_num == DCCPF_SEQUENCE_WINDOW) /* RFC 4340, 7.5.2 and 6.5 */
return 6;
return 0;
}
static u8 dccp_feat_is_valid_nn_val(u8 feat_num, u64 val)
{
switch (feat_num) {
case DCCPF_ACK_RATIO:
return val <= DCCPF_ACK_RATIO_MAX;
case DCCPF_SEQUENCE_WINDOW:
return val >= DCCPF_SEQ_WMIN && val <= DCCPF_SEQ_WMAX;
}
return 0; /* feature unknown - so we can't tell */
}
/* check that SP values are within the ranges defined in RFC 4340 */
static u8 dccp_feat_is_valid_sp_val(u8 feat_num, u8 val)
{
switch (feat_num) {
case DCCPF_CCID:
return val == DCCPC_CCID2 || val == DCCPC_CCID3;
/* Type-check Boolean feature values: */
case DCCPF_SHORT_SEQNOS:
case DCCPF_ECN_INCAPABLE:
case DCCPF_SEND_ACK_VECTOR:
case DCCPF_SEND_NDP_COUNT:
case DCCPF_DATA_CHECKSUM:
case DCCPF_SEND_LEV_RATE:
return val < 2;
case DCCPF_MIN_CSUM_COVER:
return val < 16;
}
return 0; /* feature unknown */
}
static u8 dccp_feat_sp_list_ok(u8 feat_num, u8 const *sp_list, u8 sp_len)
{
if (sp_list == NULL || sp_len < 1)
return 0;
while (sp_len--)
if (!dccp_feat_is_valid_sp_val(feat_num, *sp_list++))
return 0;
return 1;
}
/**
* dccp_feat_insert_opts - Generate FN options from current list state
* @skb: next sk_buff to be sent to the peer
* @dp: for client during handshake and general negotiation
* @dreq: used by the server only (all Changes/Confirms in LISTEN/RESPOND)
*/
int dccp_feat_insert_opts(struct dccp_sock *dp, struct dccp_request_sock *dreq,
struct sk_buff *skb)
{
struct list_head *fn = dreq ? &dreq->dreq_featneg : &dp->dccps_featneg;
struct dccp_feat_entry *pos, *next;
u8 opt, type, len, *ptr, nn_in_nbo[DCCP_OPTVAL_MAXLEN];
bool rpt;
/* put entries into @skb in the order they appear in the list */
list_for_each_entry_safe_reverse(pos, next, fn, node) {
opt = dccp_feat_genopt(pos);
type = dccp_feat_type(pos->feat_num);
rpt = false;
if (pos->empty_confirm) {
len = 0;
ptr = NULL;
} else {
if (type == FEAT_SP) {
len = pos->val.sp.len;
ptr = pos->val.sp.vec;
rpt = pos->needs_confirm;
} else if (type == FEAT_NN) {
len = dccp_feat_valid_nn_length(pos->feat_num);
ptr = nn_in_nbo;
dccp_encode_value_var(pos->val.nn, ptr, len);
} else {
DCCP_BUG("unknown feature %u", pos->feat_num);
return -1;
}
}
if (dccp_insert_fn_opt(skb, opt, pos->feat_num, ptr, len, rpt))
return -1;
if (pos->needs_mandatory && dccp_insert_option_mandatory(skb))
return -1;
/*
* Enter CHANGING after transmitting the Change option (6.6.2).
*/
if (pos->state == FEAT_INITIALISING)
pos->state = FEAT_CHANGING;
}
return 0;
}
/**
* __feat_register_nn - Register new NN value on socket
* @fn: feature-negotiation list to register with
* @feat: an NN feature from %dccp_feature_numbers
* @mandatory: use Mandatory option if 1
* @nn_val: value to register (restricted to 4 bytes)
* Note that NN features are local by definition (RFC 4340, 6.3.2).
*/
static int __feat_register_nn(struct list_head *fn, u8 feat,
u8 mandatory, u64 nn_val)
{
dccp_feat_val fval = { .nn = nn_val };
if (dccp_feat_type(feat) != FEAT_NN ||
!dccp_feat_is_valid_nn_val(feat, nn_val))
return -EINVAL;
/* Don't bother with default values, they will be activated anyway. */
if (nn_val - (u64)dccp_feat_default_value(feat) == 0)
return 0;
return dccp_feat_push_change(fn, feat, 1, mandatory, &fval);
}
/**
* __feat_register_sp - Register new SP value/list on socket
* @fn: feature-negotiation list to register with
* @feat: an SP feature from %dccp_feature_numbers
* @is_local: whether the local (1) or the remote (0) @feat is meant
* @mandatory: use Mandatory option if 1
* @sp_val: SP value followed by optional preference list
* @sp_len: length of @sp_val in bytes
*/
static int __feat_register_sp(struct list_head *fn, u8 feat, u8 is_local,
u8 mandatory, u8 const *sp_val, u8 sp_len)
{
dccp_feat_val fval;
if (dccp_feat_type(feat) != FEAT_SP ||
!dccp_feat_sp_list_ok(feat, sp_val, sp_len))
return -EINVAL;
/* Avoid negotiating alien CCIDs by only advertising supported ones */
if (feat == DCCPF_CCID && !ccid_support_check(sp_val, sp_len))
return -EOPNOTSUPP;
if (dccp_feat_clone_sp_val(&fval, sp_val, sp_len))
return -ENOMEM;
return dccp_feat_push_change(fn, feat, is_local, mandatory, &fval);
}
/**
* dccp_feat_register_sp - Register requests to change SP feature values
* @sk: client or listening socket
* @feat: one of %dccp_feature_numbers
* @is_local: whether the local (1) or remote (0) @feat is meant
* @list: array of preferred values, in descending order of preference
* @len: length of @list in bytes
*/
int dccp_feat_register_sp(struct sock *sk, u8 feat, u8 is_local,
u8 const *list, u8 len)
{ /* any changes must be registered before establishing the connection */
if (sk->sk_state != DCCP_CLOSED)
return -EISCONN;
if (dccp_feat_type(feat) != FEAT_SP)
return -EINVAL;
return __feat_register_sp(&dccp_sk(sk)->dccps_featneg, feat, is_local,
0, list, len);
}
/* Analogous to dccp_feat_register_sp(), but for non-negotiable values */
int dccp_feat_register_nn(struct sock *sk, u8 feat, u64 val)
{
/* any changes must be registered before establishing the connection */
if (sk->sk_state != DCCP_CLOSED)
return -EISCONN;
if (dccp_feat_type(feat) != FEAT_NN)
return -EINVAL;
return __feat_register_nn(&dccp_sk(sk)->dccps_featneg, feat, 0, val);
}
/*
* Tracking features whose value depend on the choice of CCID
*
* This is designed with an extension in mind so that a list walk could be done
* before activating any features. However, the existing framework was found to
* work satisfactorily up until now, the automatic verification is left open.
* When adding new CCIDs, add a corresponding dependency table here.
*/
static const struct ccid_dependency *dccp_feat_ccid_deps(u8 ccid, bool is_local)
{
static const struct ccid_dependency ccid2_dependencies[2][2] = {
/*
* CCID2 mandates Ack Vectors (RFC 4341, 4.): as CCID is a TX
* feature and Send Ack Vector is an RX feature, `is_local'
* needs to be reversed.
*/
{ /* Dependencies of the receiver-side (remote) CCID2 */
{
.dependent_feat = DCCPF_SEND_ACK_VECTOR,
.is_local = true,
.is_mandatory = true,
.val = 1
},
{ 0, 0, 0, 0 }
},
{ /* Dependencies of the sender-side (local) CCID2 */
{
.dependent_feat = DCCPF_SEND_ACK_VECTOR,
.is_local = false,
.is_mandatory = true,
.val = 1
},
{ 0, 0, 0, 0 }
}
};
static const struct ccid_dependency ccid3_dependencies[2][5] = {
{ /*
* Dependencies of the receiver-side CCID3
*/
{ /* locally disable Ack Vectors */
.dependent_feat = DCCPF_SEND_ACK_VECTOR,
.is_local = true,
.is_mandatory = false,
.val = 0
},
{ /* see below why Send Loss Event Rate is on */
.dependent_feat = DCCPF_SEND_LEV_RATE,
.is_local = true,
.is_mandatory = true,
.val = 1
},
{ /* NDP Count is needed as per RFC 4342, 6.1.1 */
.dependent_feat = DCCPF_SEND_NDP_COUNT,
.is_local = false,
.is_mandatory = true,
.val = 1
},
{ 0, 0, 0, 0 },
},
{ /*
* CCID3 at the TX side: we request that the HC-receiver
* will not send Ack Vectors (they will be ignored, so
* Mandatory is not set); we enable Send Loss Event Rate
* (Mandatory since the implementation does not support
* the Loss Intervals option of RFC 4342, 8.6).
* The last two options are for peer's information only.
*/
{
.dependent_feat = DCCPF_SEND_ACK_VECTOR,
.is_local = false,
.is_mandatory = false,
.val = 0
},
{
.dependent_feat = DCCPF_SEND_LEV_RATE,
.is_local = false,
.is_mandatory = true,
.val = 1
},
{ /* this CCID does not support Ack Ratio */
.dependent_feat = DCCPF_ACK_RATIO,
.is_local = true,
.is_mandatory = false,
.val = 0
},
{ /* tell receiver we are sending NDP counts */
.dependent_feat = DCCPF_SEND_NDP_COUNT,
.is_local = true,
.is_mandatory = false,
.val = 1
},
{ 0, 0, 0, 0 }
}
};
switch (ccid) {
case DCCPC_CCID2:
return ccid2_dependencies[is_local];
case DCCPC_CCID3:
return ccid3_dependencies[is_local];
default:
return NULL;
}
}
/**
* dccp_feat_propagate_ccid - Resolve dependencies of features on choice of CCID
* @fn: feature-negotiation list to update
* @id: CCID number to track
* @is_local: whether TX CCID (1) or RX CCID (0) is meant
* This function needs to be called after registering all other features.
*/
static int dccp_feat_propagate_ccid(struct list_head *fn, u8 id, bool is_local)
{
const struct ccid_dependency *table = dccp_feat_ccid_deps(id, is_local);
int i, rc = (table == NULL);
for (i = 0; rc == 0 && table[i].dependent_feat != DCCPF_RESERVED; i++)
if (dccp_feat_type(table[i].dependent_feat) == FEAT_SP)
rc = __feat_register_sp(fn, table[i].dependent_feat,
table[i].is_local,
table[i].is_mandatory,
&table[i].val, 1);
else
rc = __feat_register_nn(fn, table[i].dependent_feat,
table[i].is_mandatory,
table[i].val);
return rc;
}
/**
* dccp_feat_finalise_settings - Finalise settings before starting negotiation
* @dp: client or listening socket (settings will be inherited)
* This is called after all registrations (socket initialisation, sysctls, and
* sockopt calls), and before sending the first packet containing Change options
* (ie. client-Request or server-Response), to ensure internal consistency.
*/
int dccp_feat_finalise_settings(struct dccp_sock *dp)
{
struct list_head *fn = &dp->dccps_featneg;
struct dccp_feat_entry *entry;
int i = 2, ccids[2] = { -1, -1 };
/*
* Propagating CCIDs:
* 1) not useful to propagate CCID settings if this host advertises more
* than one CCID: the choice of CCID may still change - if this is
* the client, or if this is the server and the client sends
* singleton CCID values.
* 2) since is that propagate_ccid changes the list, we defer changing
* the sorted list until after the traversal.
*/
list_for_each_entry(entry, fn, node)
if (entry->feat_num == DCCPF_CCID && entry->val.sp.len == 1)
ccids[entry->is_local] = entry->val.sp.vec[0];
while (i--)
if (ccids[i] > 0 && dccp_feat_propagate_ccid(fn, ccids[i], i))
return -1;
return 0;
}
/**
* dccp_feat_server_ccid_dependencies - Resolve CCID-dependent features
* It is the server which resolves the dependencies once the CCID has been
* fully negotiated. If no CCID has been negotiated, it uses the default CCID.
*/
int dccp_feat_server_ccid_dependencies(struct dccp_request_sock *dreq)
{
struct list_head *fn = &dreq->dreq_featneg;
struct dccp_feat_entry *entry;
u8 is_local, ccid;
for (is_local = 0; is_local <= 1; is_local++) {
entry = dccp_feat_list_lookup(fn, DCCPF_CCID, is_local);
if (entry != NULL && !entry->empty_confirm)
ccid = entry->val.sp.vec[0];
else
ccid = dccp_feat_default_value(DCCPF_CCID);
if (dccp_feat_propagate_ccid(fn, ccid, is_local))
return -1;
}
return 0;
}
/* Select the first entry in @servlist that also occurs in @clilist (6.3.1) */
static int dccp_feat_preflist_match(u8 *servlist, u8 slen, u8 *clilist, u8 clen)
{
u8 c, s;
for (s = 0; s < slen; s++)
for (c = 0; c < clen; c++)
if (servlist[s] == clilist[c])
return servlist[s];
return -1;
}
/**
* dccp_feat_prefer - Move preferred entry to the start of array
* Reorder the @array_len elements in @array so that @preferred_value comes
* first. Returns >0 to indicate that @preferred_value does occur in @array.
*/
static u8 dccp_feat_prefer(u8 preferred_value, u8 *array, u8 array_len)
{
u8 i, does_occur = 0;
if (array != NULL) {
for (i = 0; i < array_len; i++)
if (array[i] == preferred_value) {
array[i] = array[0];
does_occur++;
}
if (does_occur)
array[0] = preferred_value;
}
return does_occur;
}
/**
* dccp_feat_reconcile - Reconcile SP preference lists
* @fval: SP list to reconcile into
* @arr: received SP preference list
* @len: length of @arr in bytes
* @is_server: whether this side is the server (and @fv is the server's list)
* @reorder: whether to reorder the list in @fv after reconciling with @arr
* When successful, > 0 is returned and the reconciled list is in @fval.
* A value of 0 means that negotiation failed (no shared entry).
*/
static int dccp_feat_reconcile(dccp_feat_val *fv, u8 *arr, u8 len,
bool is_server, bool reorder)
{
int rc;
if (!fv->sp.vec || !arr) {
DCCP_CRIT("NULL feature value or array");
return 0;
}
if (is_server)
rc = dccp_feat_preflist_match(fv->sp.vec, fv->sp.len, arr, len);
else
rc = dccp_feat_preflist_match(arr, len, fv->sp.vec, fv->sp.len);
if (!reorder)
return rc;
if (rc < 0)
return 0;
/*
* Reorder list: used for activating features and in dccp_insert_fn_opt.
*/
return dccp_feat_prefer(rc, fv->sp.vec, fv->sp.len);
}
/**
* dccp_feat_change_recv - Process incoming ChangeL/R options
* @fn: feature-negotiation list to update
* @is_mandatory: whether the Change was preceded by a Mandatory option
* @opt: %DCCPO_CHANGE_L or %DCCPO_CHANGE_R
* @feat: one of %dccp_feature_numbers
* @val: NN value or SP value/preference list
* @len: length of @val in bytes
* @server: whether this node is the server (1) or the client (0)
*/
static u8 dccp_feat_change_recv(struct list_head *fn, u8 is_mandatory, u8 opt,
u8 feat, u8 *val, u8 len, const bool server)
{
u8 defval, type = dccp_feat_type(feat);
const bool local = (opt == DCCPO_CHANGE_R);
struct dccp_feat_entry *entry;
dccp_feat_val fval;
if (len == 0 || type == FEAT_UNKNOWN) /* 6.1 and 6.6.8 */
goto unknown_feature_or_value;
/*
* Negotiation of NN features: Change R is invalid, so there is no
* simultaneous negotiation; hence we do not look up in the list.
*/
if (type == FEAT_NN) {
if (local || len > sizeof(fval.nn))
goto unknown_feature_or_value;
/* 6.3.2: "The feature remote MUST accept any valid value..." */
fval.nn = dccp_decode_value_var(val, len);
if (!dccp_feat_is_valid_nn_val(feat, fval.nn))
goto unknown_feature_or_value;
return dccp_feat_push_confirm(fn, feat, local, &fval);
}
/*
* Unidirectional/simultaneous negotiation of SP features (6.3.1)
*/
entry = dccp_feat_list_lookup(fn, feat, local);
if (entry == NULL) {
/*
* No particular preferences have been registered. We deal with
* this situation by assuming that all valid values are equally
* acceptable, and apply the following checks:
* - if the peer's list is a singleton, we accept a valid value;
* - if we are the server, we first try to see if the peer (the
* client) advertises the default value. If yes, we use it,
* otherwise we accept the preferred value;
* - else if we are the client, we use the first list element.
*/
if (dccp_feat_clone_sp_val(&fval, val, 1))
return DCCP_RESET_CODE_TOO_BUSY;
if (len > 1 && server) {
defval = dccp_feat_default_value(feat);
if (dccp_feat_preflist_match(&defval, 1, val, len) > -1)
fval.sp.vec[0] = defval;
} else if (!dccp_feat_is_valid_sp_val(feat, fval.sp.vec[0])) {
kfree(fval.sp.vec);
goto unknown_feature_or_value;
}
/* Treat unsupported CCIDs like invalid values */
if (feat == DCCPF_CCID && !ccid_support_check(fval.sp.vec, 1)) {
kfree(fval.sp.vec);
goto not_valid_or_not_known;
}
return dccp_feat_push_confirm(fn, feat, local, &fval);
} else if (entry->state == FEAT_UNSTABLE) { /* 6.6.2 */
return 0;
}
if (dccp_feat_reconcile(&entry->val, val, len, server, true)) {
entry->empty_confirm = 0;
} else if (is_mandatory) {
return DCCP_RESET_CODE_MANDATORY_ERROR;
} else if (entry->state == FEAT_INITIALISING) {
/*
* Failed simultaneous negotiation (server only): try to `save'
* the connection by checking whether entry contains the default
* value for @feat. If yes, send an empty Confirm to signal that
* the received Change was not understood - which implies using
* the default value.
* If this also fails, we use Reset as the last resort.
*/
WARN_ON(!server);
defval = dccp_feat_default_value(feat);
if (!dccp_feat_reconcile(&entry->val, &defval, 1, server, true))
return DCCP_RESET_CODE_OPTION_ERROR;
entry->empty_confirm = 1;
}
entry->needs_confirm = 1;
entry->needs_mandatory = 0;
entry->state = FEAT_STABLE;
return 0;
unknown_feature_or_value:
if (!is_mandatory)
return dccp_push_empty_confirm(fn, feat, local);
not_valid_or_not_known:
return is_mandatory ? DCCP_RESET_CODE_MANDATORY_ERROR
: DCCP_RESET_CODE_OPTION_ERROR;
}
/**
* dccp_feat_confirm_recv - Process received Confirm options
* @fn: feature-negotiation list to update
* @is_mandatory: whether @opt was preceded by a Mandatory option
* @opt: %DCCPO_CONFIRM_L or %DCCPO_CONFIRM_R
* @feat: one of %dccp_feature_numbers
* @val: NN value or SP value/preference list
* @len: length of @val in bytes
* @server: whether this node is server (1) or client (0)
*/
static u8 dccp_feat_confirm_recv(struct list_head *fn, u8 is_mandatory, u8 opt,
u8 feat, u8 *val, u8 len, const bool server)
{
u8 *plist, plen, type = dccp_feat_type(feat);
const bool local = (opt == DCCPO_CONFIRM_R);
struct dccp_feat_entry *entry = dccp_feat_list_lookup(fn, feat, local);
if (entry == NULL) { /* nothing queued: ignore or handle error */
if (is_mandatory && type == FEAT_UNKNOWN)
return DCCP_RESET_CODE_MANDATORY_ERROR;
if (!local && type == FEAT_NN) /* 6.3.2 */
goto confirmation_failed;
return 0;
}
if (entry->state != FEAT_CHANGING) /* 6.6.2 */
return 0;
if (len == 0) {
if (dccp_feat_must_be_understood(feat)) /* 6.6.7 */
goto confirmation_failed;
/*
* Empty Confirm during connection setup: this means reverting
* to the `old' value, which in this case is the default. Since
* we handle default values automatically when no other values
* have been set, we revert to the old value by removing this
* entry from the list.
*/
dccp_feat_list_pop(entry);
return 0;
}
if (type == FEAT_NN) {
if (len > sizeof(entry->val.nn))
goto confirmation_failed;
if (entry->val.nn == dccp_decode_value_var(val, len))
goto confirmation_succeeded;
DCCP_WARN("Bogus Confirm for non-existing value\n");
goto confirmation_failed;
}
/*
* Parsing SP Confirms: the first element of @val is the preferred
* SP value which the peer confirms, the remainder depends on @len.
* Note that only the confirmed value need to be a valid SP value.
*/
if (!dccp_feat_is_valid_sp_val(feat, *val))
goto confirmation_failed;
if (len == 1) { /* peer didn't supply a preference list */
plist = val;
plen = len;
} else { /* preferred value + preference list */
plist = val + 1;
plen = len - 1;
}
/* Check whether the peer got the reconciliation right (6.6.8) */
if (dccp_feat_reconcile(&entry->val, plist, plen, server, 0) != *val) {
DCCP_WARN("Confirm selected the wrong value %u\n", *val);
return DCCP_RESET_CODE_OPTION_ERROR;
}
entry->val.sp.vec[0] = *val;
confirmation_succeeded:
entry->state = FEAT_STABLE;
return 0;
confirmation_failed:
DCCP_WARN("Confirmation failed\n");
return is_mandatory ? DCCP_RESET_CODE_MANDATORY_ERROR
: DCCP_RESET_CODE_OPTION_ERROR;
}
/**
* dccp_feat_parse_options - Process Feature-Negotiation Options
* @sk: for general use and used by the client during connection setup
* @dreq: used by the server during connection setup
* @mandatory: whether @opt was preceded by a Mandatory option
* @opt: %DCCPO_CHANGE_L | %DCCPO_CHANGE_R | %DCCPO_CONFIRM_L | %DCCPO_CONFIRM_R
* @feat: one of %dccp_feature_numbers
* @val: value contents of @opt
* @len: length of @val in bytes
* Returns 0 on success, a Reset code for ending the connection otherwise.
*/
int dccp_feat_parse_options(struct sock *sk, struct dccp_request_sock *dreq,
u8 mandatory, u8 opt, u8 feat, u8 *val, u8 len)
{
struct dccp_sock *dp = dccp_sk(sk);
struct list_head *fn = dreq ? &dreq->dreq_featneg : &dp->dccps_featneg;
bool server = false;
switch (sk->sk_state) {
/*
* Negotiation during connection setup
*/
case DCCP_LISTEN:
server = true; /* fall through */
case DCCP_REQUESTING:
switch (opt) {
case DCCPO_CHANGE_L:
case DCCPO_CHANGE_R:
return dccp_feat_change_recv(fn, mandatory, opt, feat,
val, len, server);
case DCCPO_CONFIRM_R:
case DCCPO_CONFIRM_L:
return dccp_feat_confirm_recv(fn, mandatory, opt, feat,
val, len, server);
}
}
return 0; /* ignore FN options in all other states */
}
int dccp_feat_init(struct sock *sk)
{
struct dccp_sock *dp = dccp_sk(sk);
struct dccp_minisock *dmsk = dccp_msk(sk);
int rc;
INIT_LIST_HEAD(&dmsk->dccpms_pending); /* XXX no longer used */
INIT_LIST_HEAD(&dmsk->dccpms_conf); /* XXX no longer used */
/* Ack ratio */
rc = __feat_register_nn(&dp->dccps_featneg, DCCPF_ACK_RATIO, 0,
dp->dccps_l_ack_ratio);
return rc;
}
EXPORT_SYMBOL_GPL(dccp_feat_init);
int dccp_feat_activate_values(struct sock *sk, struct list_head *fn_list)
{
struct dccp_sock *dp = dccp_sk(sk);
struct dccp_feat_entry *cur, *next;
int idx;
dccp_feat_val *fvals[DCCP_FEAT_SUPPORTED_MAX][2] = {
[0 ... DCCP_FEAT_SUPPORTED_MAX-1] = { NULL, NULL }
};
list_for_each_entry(cur, fn_list, node) {
/*
* An empty Confirm means that either an unknown feature type
* or an invalid value was present. In the first case there is
* nothing to activate, in the other the default value is used.
*/
if (cur->empty_confirm)
continue;
idx = dccp_feat_index(cur->feat_num);
if (idx < 0) {
DCCP_BUG("Unknown feature %u", cur->feat_num);
goto activation_failed;
}
if (cur->state != FEAT_STABLE) {
DCCP_CRIT("Negotiation of %s %u failed in state %u",
cur->is_local ? "local" : "remote",
cur->feat_num, cur->state);
goto activation_failed;
}
fvals[idx][cur->is_local] = &cur->val;
}
/*
* Activate in decreasing order of index, so that the CCIDs are always
* activated as the last feature. This avoids the case where a CCID
* relies on the initialisation of one or more features that it depends
* on (e.g. Send NDP Count, Send Ack Vector, and Ack Ratio features).
*/
for (idx = DCCP_FEAT_SUPPORTED_MAX; --idx >= 0;)
if (__dccp_feat_activate(sk, idx, 0, fvals[idx][0]) ||
__dccp_feat_activate(sk, idx, 1, fvals[idx][1])) {
DCCP_CRIT("Could not activate %d", idx);
goto activation_failed;
}
/* Clean up Change options which have been confirmed already */
list_for_each_entry_safe(cur, next, fn_list, node)
if (!cur->needs_confirm)
dccp_feat_list_pop(cur);
dccp_pr_debug("Activation OK\n");
return 0;
activation_failed:
/*
* We clean up everything that may have been allocated, since
* it is difficult to track at which stage negotiation failed.
* This is ok, since all allocation functions below are robust
* against NULL arguments.
*/
ccid_hc_rx_delete(dp->dccps_hc_rx_ccid, sk);
ccid_hc_tx_delete(dp->dccps_hc_tx_ccid, sk);
dp->dccps_hc_rx_ccid = dp->dccps_hc_tx_ccid = NULL;
dccp_ackvec_free(dp->dccps_hc_rx_ackvec);
dp->dccps_hc_rx_ackvec = NULL;
return -1;
}
#ifdef CONFIG_IP_DCCP_DEBUG
const char *dccp_feat_typename(const u8 type)
{
switch(type) {
case DCCPO_CHANGE_L: return("ChangeL");
case DCCPO_CONFIRM_L: return("ConfirmL");
case DCCPO_CHANGE_R: return("ChangeR");
case DCCPO_CONFIRM_R: return("ConfirmR");
/* the following case must not appear in feature negotation */
default: dccp_pr_debug("unknown type %d [BUG!]\n", type);
}
return NULL;
}
EXPORT_SYMBOL_GPL(dccp_feat_typename);
const char *dccp_feat_name(const u8 feat)
{
static const char *feature_names[] = {
[DCCPF_RESERVED] = "Reserved",
[DCCPF_CCID] = "CCID",
[DCCPF_SHORT_SEQNOS] = "Allow Short Seqnos",
[DCCPF_SEQUENCE_WINDOW] = "Sequence Window",
[DCCPF_ECN_INCAPABLE] = "ECN Incapable",
[DCCPF_ACK_RATIO] = "Ack Ratio",
[DCCPF_SEND_ACK_VECTOR] = "Send ACK Vector",
[DCCPF_SEND_NDP_COUNT] = "Send NDP Count",
[DCCPF_MIN_CSUM_COVER] = "Min. Csum Coverage",
[DCCPF_DATA_CHECKSUM] = "Send Data Checksum",
};
if (feat > DCCPF_DATA_CHECKSUM && feat < DCCPF_MIN_CCID_SPECIFIC)
return feature_names[DCCPF_RESERVED];
if (feat == DCCPF_SEND_LEV_RATE)
return "Send Loss Event Rate";
if (feat >= DCCPF_MIN_CCID_SPECIFIC)
return "CCID-specific";
return feature_names[feat];
}
EXPORT_SYMBOL_GPL(dccp_feat_name);
#endif /* CONFIG_IP_DCCP_DEBUG */