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41719b0309
linux/net/dccp/options.c
Gerrit Renker 6fdd34d43b dccp ccid-2: Phase out the use of boolean Ack Vector sysctl 
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>
2008-12-08 01:19:06 -08:00

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/*
* net/dccp/options.c
*
* An implementation of the DCCP protocol
* Copyright (c) 2005 Aristeu Sergio Rozanski Filho <aris@cathedrallabs.org>
* Copyright (c) 2005 Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
* Copyright (c) 2005 Ian McDonald <ian.mcdonald@jandi.co.nz>
*
* 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/dccp.h>
#include <linux/module.h>
#include <linux/types.h>
#include <asm/unaligned.h>
#include <linux/kernel.h>
#include <linux/skbuff.h>
#include "ackvec.h"
#include "ccid.h"
#include "dccp.h"
#include "feat.h"
int sysctl_dccp_feat_sequence_window = DCCPF_INITIAL_SEQUENCE_WINDOW;
int sysctl_dccp_feat_rx_ccid = DCCPF_INITIAL_CCID;
int sysctl_dccp_feat_tx_ccid = DCCPF_INITIAL_CCID;
u64 dccp_decode_value_var(const u8 *bf, const u8 len)
{
u64 value = 0;
if (len >= DCCP_OPTVAL_MAXLEN)
value += ((u64)*bf++) << 40;
if (len > 4)
value += ((u64)*bf++) << 32;
if (len > 3)
value += ((u64)*bf++) << 24;
if (len > 2)
value += ((u64)*bf++) << 16;
if (len > 1)
value += ((u64)*bf++) << 8;
if (len > 0)
value += *bf;
return value;
}
/**
* dccp_parse_options - Parse DCCP options present in @skb
* @sk: client|server|listening dccp socket (when @dreq != NULL)
* @dreq: request socket to use during connection setup, or NULL
*/
int dccp_parse_options(struct sock *sk, struct dccp_request_sock *dreq,
struct sk_buff *skb)
{
struct dccp_sock *dp = dccp_sk(sk);
const struct dccp_hdr *dh = dccp_hdr(skb);
const u8 pkt_type = DCCP_SKB_CB(skb)->dccpd_type;
u64 ackno = DCCP_SKB_CB(skb)->dccpd_ack_seq;
unsigned char *options = (unsigned char *)dh + dccp_hdr_len(skb);
unsigned char *opt_ptr = options;
const unsigned char *opt_end = (unsigned char *)dh +
(dh->dccph_doff * 4);
struct dccp_options_received *opt_recv = &dp->dccps_options_received;
unsigned char opt, len;
unsigned char *uninitialized_var(value);
u32 elapsed_time;
__be32 opt_val;
int rc;
int mandatory = 0;
memset(opt_recv, 0, sizeof(*opt_recv));
opt = len = 0;
while (opt_ptr != opt_end) {
opt = *opt_ptr++;
len = 0;
value = NULL;
/* Check if this isn't a single byte option */
if (opt > DCCPO_MAX_RESERVED) {
if (opt_ptr == opt_end)
goto out_nonsensical_length;
len = *opt_ptr++;
if (len < 2)
goto out_nonsensical_length;
/*
* Remove the type and len fields, leaving
* just the value size
*/
len -= 2;
value = opt_ptr;
opt_ptr += len;
if (opt_ptr > opt_end)
goto out_nonsensical_length;
}
/*
* CCID-Specific Options (from RFC 4340, sec. 10.3):
*
* Option numbers 128 through 191 are for options sent from the
* HC-Sender to the HC-Receiver; option numbers 192 through 255
* are for options sent from the HC-Receiver to the HC-Sender.
*
* CCID-specific options are ignored during connection setup, as
* negotiation may still be in progress (see RFC 4340, 10.3).
* The same applies to Ack Vectors, as these depend on the CCID.
*
*/
if (dreq != NULL && (opt >= 128 ||
opt == DCCPO_ACK_VECTOR_0 || opt == DCCPO_ACK_VECTOR_1))
goto ignore_option;
switch (opt) {
case DCCPO_PADDING:
break;
case DCCPO_MANDATORY:
if (mandatory)
goto out_invalid_option;
if (pkt_type != DCCP_PKT_DATA)
mandatory = 1;
break;
case DCCPO_NDP_COUNT:
if (len > 6)
goto out_invalid_option;
opt_recv->dccpor_ndp = dccp_decode_value_var(value, len);
dccp_pr_debug("%s opt: NDP count=%llu\n", dccp_role(sk),
(unsigned long long)opt_recv->dccpor_ndp);
break;
case DCCPO_CHANGE_L ... DCCPO_CONFIRM_R:
if (pkt_type == DCCP_PKT_DATA) /* RFC 4340, 6 */
break;
rc = dccp_feat_parse_options(sk, dreq, mandatory, opt,
*value, value + 1, len - 1);
if (rc)
goto out_featneg_failed;
break;
case DCCPO_ACK_VECTOR_0:
case DCCPO_ACK_VECTOR_1:
if (dccp_packet_without_ack(skb)) /* RFC 4340, 11.4 */
break;
if (dp->dccps_hc_rx_ackvec != NULL &&
dccp_ackvec_parse(sk, skb, &ackno, opt, value, len))
goto out_invalid_option;
break;
case DCCPO_TIMESTAMP:
if (len != 4)
goto out_invalid_option;
/*
* RFC 4340 13.1: "The precise time corresponding to
* Timestamp Value zero is not specified". We use
* zero to indicate absence of a meaningful timestamp.
*/
opt_val = get_unaligned((__be32 *)value);
if (unlikely(opt_val == 0)) {
DCCP_WARN("Timestamp with zero value\n");
break;
}
if (dreq != NULL) {
dreq->dreq_timestamp_echo = ntohl(opt_val);
dreq->dreq_timestamp_time = dccp_timestamp();
} else {
opt_recv->dccpor_timestamp =
dp->dccps_timestamp_echo = ntohl(opt_val);
dp->dccps_timestamp_time = dccp_timestamp();
}
dccp_pr_debug("%s rx opt: TIMESTAMP=%u, ackno=%llu\n",
dccp_role(sk), ntohl(opt_val),
(unsigned long long)
DCCP_SKB_CB(skb)->dccpd_ack_seq);
break;
case DCCPO_TIMESTAMP_ECHO:
if (len != 4 && len != 6 && len != 8)
goto out_invalid_option;
opt_val = get_unaligned((__be32 *)value);
opt_recv->dccpor_timestamp_echo = ntohl(opt_val);
dccp_pr_debug("%s rx opt: TIMESTAMP_ECHO=%u, len=%d, "
"ackno=%llu", dccp_role(sk),
opt_recv->dccpor_timestamp_echo,
len + 2,
(unsigned long long)
DCCP_SKB_CB(skb)->dccpd_ack_seq);
value += 4;
if (len == 4) { /* no elapsed time included */
dccp_pr_debug_cat("\n");
break;
}
if (len == 6) { /* 2-byte elapsed time */
__be16 opt_val2 = get_unaligned((__be16 *)value);
elapsed_time = ntohs(opt_val2);
} else { /* 4-byte elapsed time */
opt_val = get_unaligned((__be32 *)value);
elapsed_time = ntohl(opt_val);
}
dccp_pr_debug_cat(", ELAPSED_TIME=%u\n", elapsed_time);
/* Give precedence to the biggest ELAPSED_TIME */
if (elapsed_time > opt_recv->dccpor_elapsed_time)
opt_recv->dccpor_elapsed_time = elapsed_time;
break;
case DCCPO_ELAPSED_TIME:
if (dccp_packet_without_ack(skb)) /* RFC 4340, 13.2 */
break;
if (len == 2) {
__be16 opt_val2 = get_unaligned((__be16 *)value);
elapsed_time = ntohs(opt_val2);
} else if (len == 4) {
opt_val = get_unaligned((__be32 *)value);
elapsed_time = ntohl(opt_val);
} else {
goto out_invalid_option;
}
if (elapsed_time > opt_recv->dccpor_elapsed_time)
opt_recv->dccpor_elapsed_time = elapsed_time;
dccp_pr_debug("%s rx opt: ELAPSED_TIME=%d\n",
dccp_role(sk), elapsed_time);
break;
case 128 ... 191: {
const u16 idx = value - options;
if (ccid_hc_rx_parse_options(dp->dccps_hc_rx_ccid, sk,
opt, len, idx,
value) != 0)
goto out_invalid_option;
}
break;
case 192 ... 255: {
const u16 idx = value - options;
if (ccid_hc_tx_parse_options(dp->dccps_hc_tx_ccid, sk,
opt, len, idx,
value) != 0)
goto out_invalid_option;
}
break;
default:
DCCP_CRIT("DCCP(%p): option %d(len=%d) not "
"implemented, ignoring", sk, opt, len);
break;
}
ignore_option:
if (opt != DCCPO_MANDATORY)
mandatory = 0;
}
/* mandatory was the last byte in option list -> reset connection */
if (mandatory)
goto out_invalid_option;
out_nonsensical_length:
/* RFC 4340, 5.8: ignore option and all remaining option space */
return 0;
out_invalid_option:
DCCP_INC_STATS_BH(DCCP_MIB_INVALIDOPT);
rc = DCCP_RESET_CODE_OPTION_ERROR;
out_featneg_failed:
DCCP_WARN("DCCP(%p): Option %d (len=%d) error=%u\n", sk, opt, len, rc);
DCCP_SKB_CB(skb)->dccpd_reset_code = rc;
DCCP_SKB_CB(skb)->dccpd_reset_data[0] = opt;
DCCP_SKB_CB(skb)->dccpd_reset_data[1] = len > 0 ? value[0] : 0;
DCCP_SKB_CB(skb)->dccpd_reset_data[2] = len > 1 ? value[1] : 0;
return -1;
}
EXPORT_SYMBOL_GPL(dccp_parse_options);
void dccp_encode_value_var(const u64 value, u8 *to, const u8 len)
{
if (len >= DCCP_OPTVAL_MAXLEN)
*to++ = (value & 0xFF0000000000ull) >> 40;
if (len > 4)
*to++ = (value & 0xFF00000000ull) >> 32;
if (len > 3)
*to++ = (value & 0xFF000000) >> 24;
if (len > 2)
*to++ = (value & 0xFF0000) >> 16;
if (len > 1)
*to++ = (value & 0xFF00) >> 8;
if (len > 0)
*to++ = (value & 0xFF);
}
static inline u8 dccp_ndp_len(const u64 ndp)
{
if (likely(ndp <= 0xFF))
return 1;
return likely(ndp <= USHORT_MAX) ? 2 : (ndp <= UINT_MAX ? 4 : 6);
}
int dccp_insert_option(struct sock *sk, struct sk_buff *skb,
const unsigned char option,
const void *value, const unsigned char len)
{
unsigned char *to;
if (DCCP_SKB_CB(skb)->dccpd_opt_len + len + 2 > DCCP_MAX_OPT_LEN)
return -1;
DCCP_SKB_CB(skb)->dccpd_opt_len += len + 2;
to = skb_push(skb, len + 2);
*to++ = option;
*to++ = len + 2;
memcpy(to, value, len);
return 0;
}
EXPORT_SYMBOL_GPL(dccp_insert_option);
static int dccp_insert_option_ndp(struct sock *sk, struct sk_buff *skb)
{
struct dccp_sock *dp = dccp_sk(sk);
u64 ndp = dp->dccps_ndp_count;
if (dccp_non_data_packet(skb))
++dp->dccps_ndp_count;
else
dp->dccps_ndp_count = 0;
if (ndp > 0) {
unsigned char *ptr;
const int ndp_len = dccp_ndp_len(ndp);
const int len = ndp_len + 2;
if (DCCP_SKB_CB(skb)->dccpd_opt_len + len > DCCP_MAX_OPT_LEN)
return -1;
DCCP_SKB_CB(skb)->dccpd_opt_len += len;
ptr = skb_push(skb, len);
*ptr++ = DCCPO_NDP_COUNT;
*ptr++ = len;
dccp_encode_value_var(ndp, ptr, ndp_len);
}
return 0;
}
static inline int dccp_elapsed_time_len(const u32 elapsed_time)
{
return elapsed_time == 0 ? 0 : elapsed_time <= 0xFFFF ? 2 : 4;
}
int dccp_insert_option_elapsed_time(struct sock *sk, struct sk_buff *skb,
u32 elapsed_time)
{
const int elapsed_time_len = dccp_elapsed_time_len(elapsed_time);
const int len = 2 + elapsed_time_len;
unsigned char *to;
if (elapsed_time_len == 0)
return 0;
if (DCCP_SKB_CB(skb)->dccpd_opt_len + len > DCCP_MAX_OPT_LEN)
return -1;
DCCP_SKB_CB(skb)->dccpd_opt_len += len;
to = skb_push(skb, len);
*to++ = DCCPO_ELAPSED_TIME;
*to++ = len;
if (elapsed_time_len == 2) {
const __be16 var16 = htons((u16)elapsed_time);
memcpy(to, &var16, 2);
} else {
const __be32 var32 = htonl(elapsed_time);
memcpy(to, &var32, 4);
}
return 0;
}
EXPORT_SYMBOL_GPL(dccp_insert_option_elapsed_time);
int dccp_insert_option_timestamp(struct sock *sk, struct sk_buff *skb)
{
__be32 now = htonl(dccp_timestamp());
/* yes this will overflow but that is the point as we want a
* 10 usec 32 bit timer which mean it wraps every 11.9 hours */
return dccp_insert_option(sk, skb, DCCPO_TIMESTAMP, &now, sizeof(now));
}
EXPORT_SYMBOL_GPL(dccp_insert_option_timestamp);
static int dccp_insert_option_timestamp_echo(struct dccp_sock *dp,
struct dccp_request_sock *dreq,
struct sk_buff *skb)
{
__be32 tstamp_echo;
unsigned char *to;
u32 elapsed_time, elapsed_time_len, len;
if (dreq != NULL) {
elapsed_time = dccp_timestamp() - dreq->dreq_timestamp_time;
tstamp_echo = htonl(dreq->dreq_timestamp_echo);
dreq->dreq_timestamp_echo = 0;
} else {
elapsed_time = dccp_timestamp() - dp->dccps_timestamp_time;
tstamp_echo = htonl(dp->dccps_timestamp_echo);
dp->dccps_timestamp_echo = 0;
}
elapsed_time_len = dccp_elapsed_time_len(elapsed_time);
len = 6 + elapsed_time_len;
if (DCCP_SKB_CB(skb)->dccpd_opt_len + len > DCCP_MAX_OPT_LEN)
return -1;
DCCP_SKB_CB(skb)->dccpd_opt_len += len;
to = skb_push(skb, len);
*to++ = DCCPO_TIMESTAMP_ECHO;
*to++ = len;
memcpy(to, &tstamp_echo, 4);
to += 4;
if (elapsed_time_len == 2) {
const __be16 var16 = htons((u16)elapsed_time);
memcpy(to, &var16, 2);
} else if (elapsed_time_len == 4) {
const __be32 var32 = htonl(elapsed_time);
memcpy(to, &var32, 4);
}
return 0;
}
/**
* dccp_insert_option_mandatory - Mandatory option (5.8.2)
* Note that since we are using skb_push, this function needs to be called
* _after_ inserting the option it is supposed to influence (stack order).
*/
int dccp_insert_option_mandatory(struct sk_buff *skb)
{
if (DCCP_SKB_CB(skb)->dccpd_opt_len >= DCCP_MAX_OPT_LEN)
return -1;
DCCP_SKB_CB(skb)->dccpd_opt_len++;
*skb_push(skb, 1) = DCCPO_MANDATORY;
return 0;
}
/**
* dccp_insert_fn_opt - Insert single Feature-Negotiation option into @skb
* @type: %DCCPO_CHANGE_L, %DCCPO_CHANGE_R, %DCCPO_CONFIRM_L, %DCCPO_CONFIRM_R
* @feat: one out of %dccp_feature_numbers
* @val: NN value or SP array (preferred element first) to copy
* @len: true length of @val in bytes (excluding first element repetition)
* @repeat_first: whether to copy the first element of @val twice
* The last argument is used to construct Confirm options, where the preferred
* value and the preference list appear separately (RFC 4340, 6.3.1). Preference
* lists are kept such that the preferred entry is always first, so we only need
* to copy twice, and avoid the overhead of cloning into a bigger array.
*/
int dccp_insert_fn_opt(struct sk_buff *skb, u8 type, u8 feat,
u8 *val, u8 len, bool repeat_first)
{
u8 tot_len, *to;
/* take the `Feature' field and possible repetition into account */
if (len > (DCCP_SINGLE_OPT_MAXLEN - 2)) {
DCCP_WARN("length %u for feature %u too large\n", len, feat);
return -1;
}
if (unlikely(val == NULL || len == 0))
len = repeat_first = 0;
tot_len = 3 + repeat_first + len;
if (DCCP_SKB_CB(skb)->dccpd_opt_len + tot_len > DCCP_MAX_OPT_LEN) {
DCCP_WARN("packet too small for feature %d option!\n", feat);
return -1;
}
DCCP_SKB_CB(skb)->dccpd_opt_len += tot_len;
to = skb_push(skb, tot_len);
*to++ = type;
*to++ = tot_len;
*to++ = feat;
if (repeat_first)
*to++ = *val;
if (len)
memcpy(to, val, len);
dccp_pr_debug("%s(%s (%d), ...), length %d\n",
dccp_feat_typename(type),
dccp_feat_name(feat), feat, len);
return 0;
}
/* The length of all options needs to be a multiple of 4 (5.8) */
static void dccp_insert_option_padding(struct sk_buff *skb)
{
int padding = DCCP_SKB_CB(skb)->dccpd_opt_len % 4;
if (padding != 0) {
padding = 4 - padding;
memset(skb_push(skb, padding), 0, padding);
DCCP_SKB_CB(skb)->dccpd_opt_len += padding;
}
}
int dccp_insert_options(struct sock *sk, struct sk_buff *skb)
{
struct dccp_sock *dp = dccp_sk(sk);
DCCP_SKB_CB(skb)->dccpd_opt_len = 0;
if (dp->dccps_send_ndp_count && dccp_insert_option_ndp(sk, skb))
return -1;
if (DCCP_SKB_CB(skb)->dccpd_type != DCCP_PKT_DATA) {
/* Feature Negotiation */
if (dccp_feat_insert_opts(dp, NULL, skb))
return -1;
if (DCCP_SKB_CB(skb)->dccpd_type == DCCP_PKT_REQUEST) {
/*
* Obtain RTT sample from Request/Response exchange.
* This is currently used in CCID 3 initialisation.
*/
if (dccp_insert_option_timestamp(sk, skb))
return -1;
} else if (dp->dccps_hc_rx_ackvec != NULL &&
dccp_ackvec_pending(dp->dccps_hc_rx_ackvec) &&
dccp_insert_option_ackvec(sk, skb)) {
return -1;
}
}
if (dp->dccps_hc_rx_insert_options) {
if (ccid_hc_rx_insert_options(dp->dccps_hc_rx_ccid, sk, skb))
return -1;
dp->dccps_hc_rx_insert_options = 0;
}
if (dp->dccps_timestamp_echo != 0 &&
dccp_insert_option_timestamp_echo(dp, NULL, skb))
return -1;
dccp_insert_option_padding(skb);
return 0;
}
int dccp_insert_options_rsk(struct dccp_request_sock *dreq, struct sk_buff *skb)
{
DCCP_SKB_CB(skb)->dccpd_opt_len = 0;
if (dccp_feat_insert_opts(NULL, dreq, skb))
return -1;
if (dreq->dreq_timestamp_echo != 0 &&
dccp_insert_option_timestamp_echo(NULL, dreq, skb))
return -1;
dccp_insert_option_padding(skb);
return 0;
}
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