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linux/net/dccp/ccids/ccid3.c
Mathias Krause 7b07f8eb75 dccp: fix info leak via getsockopt(DCCP_SOCKOPT_CCID_TX_INFO) 
The CCID3 code fails to initialize the trailing padding bytes of struct
tfrc_tx_info added for alignment on 64 bit architectures. It that for
potentially leaks four bytes kernel stack via the getsockopt() syscall.
Add an explicit memset(0) before filling the structure to avoid the
info leak.

Signed-off-by: Mathias Krause <minipli@googlemail.com>
Cc: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>
2012-08-15 21:36:31 -07:00

870 lines
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/*
* Copyright (c) 2007 The University of Aberdeen, Scotland, UK
* Copyright (c) 2005-7 The University of Waikato, Hamilton, New Zealand.
* Copyright (c) 2005-7 Ian McDonald <ian.mcdonald@jandi.co.nz>
*
* An implementation of the DCCP protocol
*
* This code has been developed by the University of Waikato WAND
* research group. For further information please see http://www.wand.net.nz/
*
* This code also uses code from Lulea University, rereleased as GPL by its
* authors:
* Copyright (c) 2003 Nils-Erik Mattsson, Joacim Haggmark, Magnus Erixzon
*
* Changes to meet Linux coding standards, to make it meet latest ccid3 draft
* and to make it work as a loadable module in the DCCP stack written by
* Arnaldo Carvalho de Melo <acme@conectiva.com.br>.
*
* Copyright (c) 2005 Arnaldo Carvalho de Melo <acme@conectiva.com.br>
*
* 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.
*/
#include "../dccp.h"
#include "ccid3.h"
#include <asm/unaligned.h>
#ifdef CONFIG_IP_DCCP_CCID3_DEBUG
static bool ccid3_debug;
#define ccid3_pr_debug(format, a...) DCCP_PR_DEBUG(ccid3_debug, format, ##a)
#else
#define ccid3_pr_debug(format, a...)
#endif
/*
* Transmitter Half-Connection Routines
*/
#ifdef CONFIG_IP_DCCP_CCID3_DEBUG
static const char *ccid3_tx_state_name(enum ccid3_hc_tx_states state)
{
static const char *const ccid3_state_names[] = {
[TFRC_SSTATE_NO_SENT] = "NO_SENT",
[TFRC_SSTATE_NO_FBACK] = "NO_FBACK",
[TFRC_SSTATE_FBACK] = "FBACK",
};
return ccid3_state_names[state];
}
#endif
static void ccid3_hc_tx_set_state(struct sock *sk,
enum ccid3_hc_tx_states state)
{
struct ccid3_hc_tx_sock *hc = ccid3_hc_tx_sk(sk);
enum ccid3_hc_tx_states oldstate = hc->tx_state;
ccid3_pr_debug("%s(%p) %-8.8s -> %s\n",
dccp_role(sk), sk, ccid3_tx_state_name(oldstate),
ccid3_tx_state_name(state));
WARN_ON(state == oldstate);
hc->tx_state = state;
}
/*
* Compute the initial sending rate X_init in the manner of RFC 3390:
*
* X_init = min(4 * s, max(2 * s, 4380 bytes)) / RTT
*
* Note that RFC 3390 uses MSS, RFC 4342 refers to RFC 3390, and rfc3448bis
* (rev-02) clarifies the use of RFC 3390 with regard to the above formula.
* For consistency with other parts of the code, X_init is scaled by 2^6.
*/
static inline u64 rfc3390_initial_rate(struct sock *sk)
{
const struct ccid3_hc_tx_sock *hc = ccid3_hc_tx_sk(sk);
const __u32 w_init = clamp_t(__u32, 4380U, 2 * hc->tx_s, 4 * hc->tx_s);
return scaled_div(w_init << 6, hc->tx_rtt);
}
/**
* ccid3_update_send_interval - Calculate new t_ipi = s / X_inst
* This respects the granularity of X_inst (64 * bytes/second).
*/
static void ccid3_update_send_interval(struct ccid3_hc_tx_sock *hc)
{
hc->tx_t_ipi = scaled_div32(((u64)hc->tx_s) << 6, hc->tx_x);
DCCP_BUG_ON(hc->tx_t_ipi == 0);
ccid3_pr_debug("t_ipi=%u, s=%u, X=%u\n", hc->tx_t_ipi,
hc->tx_s, (unsigned int)(hc->tx_x >> 6));
}
static u32 ccid3_hc_tx_idle_rtt(struct ccid3_hc_tx_sock *hc, ktime_t now)
{
u32 delta = ktime_us_delta(now, hc->tx_t_last_win_count);
return delta / hc->tx_rtt;
}
/**
* ccid3_hc_tx_update_x - Update allowed sending rate X
* @stamp: most recent time if available - can be left NULL.
*
* This function tracks draft rfc3448bis, check there for latest details.
*
* Note: X and X_recv are both stored in units of 64 * bytes/second, to support
* fine-grained resolution of sending rates. This requires scaling by 2^6
* throughout the code. Only X_calc is unscaled (in bytes/second).
*
*/
static void ccid3_hc_tx_update_x(struct sock *sk, ktime_t *stamp)
{
struct ccid3_hc_tx_sock *hc = ccid3_hc_tx_sk(sk);
__u64 min_rate = 2 * hc->tx_x_recv;
const __u64 old_x = hc->tx_x;
ktime_t now = stamp ? *stamp : ktime_get_real();
/*
* Handle IDLE periods: do not reduce below RFC3390 initial sending rate
* when idling [RFC 4342, 5.1]. Definition of idling is from rfc3448bis:
* a sender is idle if it has not sent anything over a 2-RTT-period.
* For consistency with X and X_recv, min_rate is also scaled by 2^6.
*/
if (ccid3_hc_tx_idle_rtt(hc, now) >= 2) {
min_rate = rfc3390_initial_rate(sk);
min_rate = max(min_rate, 2 * hc->tx_x_recv);
}
if (hc->tx_p > 0) {
hc->tx_x = min(((__u64)hc->tx_x_calc) << 6, min_rate);
hc->tx_x = max(hc->tx_x, (((__u64)hc->tx_s) << 6) / TFRC_T_MBI);
} else if (ktime_us_delta(now, hc->tx_t_ld) - (s64)hc->tx_rtt >= 0) {
hc->tx_x = min(2 * hc->tx_x, min_rate);
hc->tx_x = max(hc->tx_x,
scaled_div(((__u64)hc->tx_s) << 6, hc->tx_rtt));
hc->tx_t_ld = now;
}
if (hc->tx_x != old_x) {
ccid3_pr_debug("X_prev=%u, X_now=%u, X_calc=%u, "
"X_recv=%u\n", (unsigned int)(old_x >> 6),
(unsigned int)(hc->tx_x >> 6), hc->tx_x_calc,
(unsigned int)(hc->tx_x_recv >> 6));
ccid3_update_send_interval(hc);
}
}
/**
* ccid3_hc_tx_update_s - Track the mean packet size `s'
* @len: DCCP packet payload size in bytes
*
* cf. RFC 4342, 5.3 and RFC 3448, 4.1
*/
static inline void ccid3_hc_tx_update_s(struct ccid3_hc_tx_sock *hc, int len)
{
const u16 old_s = hc->tx_s;
hc->tx_s = tfrc_ewma(hc->tx_s, len, 9);
if (hc->tx_s != old_s)
ccid3_update_send_interval(hc);
}
/*
* Update Window Counter using the algorithm from [RFC 4342, 8.1].
* As elsewhere, RTT > 0 is assumed by using dccp_sample_rtt().
*/
static inline void ccid3_hc_tx_update_win_count(struct ccid3_hc_tx_sock *hc,
ktime_t now)
{
u32 delta = ktime_us_delta(now, hc->tx_t_last_win_count),
quarter_rtts = (4 * delta) / hc->tx_rtt;
if (quarter_rtts > 0) {
hc->tx_t_last_win_count = now;
hc->tx_last_win_count += min(quarter_rtts, 5U);
hc->tx_last_win_count &= 0xF; /* mod 16 */
}
}
static void ccid3_hc_tx_no_feedback_timer(unsigned long data)
{
struct sock *sk = (struct sock *)data;
struct ccid3_hc_tx_sock *hc = ccid3_hc_tx_sk(sk);
unsigned long t_nfb = USEC_PER_SEC / 5;
bh_lock_sock(sk);
if (sock_owned_by_user(sk)) {
/* Try again later. */
/* XXX: set some sensible MIB */
goto restart_timer;
}
ccid3_pr_debug("%s(%p, state=%s) - entry\n", dccp_role(sk), sk,
ccid3_tx_state_name(hc->tx_state));
/* Ignore and do not restart after leaving the established state */
if ((1 << sk->sk_state) & ~(DCCPF_OPEN | DCCPF_PARTOPEN))
goto out;
/* Reset feedback state to "no feedback received" */
if (hc->tx_state == TFRC_SSTATE_FBACK)
ccid3_hc_tx_set_state(sk, TFRC_SSTATE_NO_FBACK);
/*
* Determine new allowed sending rate X as per draft rfc3448bis-00, 4.4
* RTO is 0 if and only if no feedback has been received yet.
*/
if (hc->tx_t_rto == 0 || hc->tx_p == 0) {
/* halve send rate directly */
hc->tx_x = max(hc->tx_x / 2,
(((__u64)hc->tx_s) << 6) / TFRC_T_MBI);
ccid3_update_send_interval(hc);
} else {
/*
* Modify the cached value of X_recv
*
* If (X_calc > 2 * X_recv)
* X_recv = max(X_recv / 2, s / (2 * t_mbi));
* Else
* X_recv = X_calc / 4;
*
* Note that X_recv is scaled by 2^6 while X_calc is not
*/
if (hc->tx_x_calc > (hc->tx_x_recv >> 5))
hc->tx_x_recv =
max(hc->tx_x_recv / 2,
(((__u64)hc->tx_s) << 6) / (2*TFRC_T_MBI));
else {
hc->tx_x_recv = hc->tx_x_calc;
hc->tx_x_recv <<= 4;
}
ccid3_hc_tx_update_x(sk, NULL);
}
ccid3_pr_debug("Reduced X to %llu/64 bytes/sec\n",
(unsigned long long)hc->tx_x);
/*
* Set new timeout for the nofeedback timer.
* See comments in packet_recv() regarding the value of t_RTO.
*/
if (unlikely(hc->tx_t_rto == 0)) /* no feedback received yet */
t_nfb = TFRC_INITIAL_TIMEOUT;
else
t_nfb = max(hc->tx_t_rto, 2 * hc->tx_t_ipi);
restart_timer:
sk_reset_timer(sk, &hc->tx_no_feedback_timer,
jiffies + usecs_to_jiffies(t_nfb));
out:
bh_unlock_sock(sk);
sock_put(sk);
}
/**
* ccid3_hc_tx_send_packet - Delay-based dequeueing of TX packets
* @skb: next packet candidate to send on @sk
*
* This function uses the convention of ccid_packet_dequeue_eval() and
* returns a millisecond-delay value between 0 and t_mbi = 64000 msec.
*/
static int ccid3_hc_tx_send_packet(struct sock *sk, struct sk_buff *skb)
{
struct dccp_sock *dp = dccp_sk(sk);
struct ccid3_hc_tx_sock *hc = ccid3_hc_tx_sk(sk);
ktime_t now = ktime_get_real();
s64 delay;
/*
* This function is called only for Data and DataAck packets. Sending
* zero-sized Data(Ack)s is theoretically possible, but for congestion
* control this case is pathological - ignore it.
*/
if (unlikely(skb->len == 0))
return -EBADMSG;
if (hc->tx_state == TFRC_SSTATE_NO_SENT) {
sk_reset_timer(sk, &hc->tx_no_feedback_timer, (jiffies +
usecs_to_jiffies(TFRC_INITIAL_TIMEOUT)));
hc->tx_last_win_count = 0;
hc->tx_t_last_win_count = now;
/* Set t_0 for initial packet */
hc->tx_t_nom = now;
hc->tx_s = skb->len;
/*
* Use initial RTT sample when available: recommended by erratum
* to RFC 4342. This implements the initialisation procedure of
* draft rfc3448bis, section 4.2. Remember, X is scaled by 2^6.
*/
if (dp->dccps_syn_rtt) {
ccid3_pr_debug("SYN RTT = %uus\n", dp->dccps_syn_rtt);
hc->tx_rtt = dp->dccps_syn_rtt;
hc->tx_x = rfc3390_initial_rate(sk);
hc->tx_t_ld = now;
} else {
/*
* Sender does not have RTT sample:
* - set fallback RTT (RFC 4340, 3.4) since a RTT value
* is needed in several parts (e.g. window counter);
* - set sending rate X_pps = 1pps as per RFC 3448, 4.2.
*/
hc->tx_rtt = DCCP_FALLBACK_RTT;
hc->tx_x = hc->tx_s;
hc->tx_x <<= 6;
}
ccid3_update_send_interval(hc);
ccid3_hc_tx_set_state(sk, TFRC_SSTATE_NO_FBACK);
} else {
delay = ktime_us_delta(hc->tx_t_nom, now);
ccid3_pr_debug("delay=%ld\n", (long)delay);
/*
* Scheduling of packet transmissions (RFC 5348, 8.3)
*
* if (t_now > t_nom - delta)
* // send the packet now
* else
* // send the packet in (t_nom - t_now) milliseconds.
*/
if (delay >= TFRC_T_DELTA)
return (u32)delay / USEC_PER_MSEC;
ccid3_hc_tx_update_win_count(hc, now);
}
/* prepare to send now (add options etc.) */
dp->dccps_hc_tx_insert_options = 1;
DCCP_SKB_CB(skb)->dccpd_ccval = hc->tx_last_win_count;
/* set the nominal send time for the next following packet */
hc->tx_t_nom = ktime_add_us(hc->tx_t_nom, hc->tx_t_ipi);
return CCID_PACKET_SEND_AT_ONCE;
}
static void ccid3_hc_tx_packet_sent(struct sock *sk, unsigned int len)
{
struct ccid3_hc_tx_sock *hc = ccid3_hc_tx_sk(sk);
ccid3_hc_tx_update_s(hc, len);
if (tfrc_tx_hist_add(&hc->tx_hist, dccp_sk(sk)->dccps_gss))
DCCP_CRIT("packet history - out of memory!");
}
static void ccid3_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb)
{
struct ccid3_hc_tx_sock *hc = ccid3_hc_tx_sk(sk);
struct tfrc_tx_hist_entry *acked;
ktime_t now;
unsigned long t_nfb;
u32 r_sample;
/* we are only interested in ACKs */
if (!(DCCP_SKB_CB(skb)->dccpd_type == DCCP_PKT_ACK ||
DCCP_SKB_CB(skb)->dccpd_type == DCCP_PKT_DATAACK))
return;
/*
* Locate the acknowledged packet in the TX history.
*
* Returning "entry not found" here can for instance happen when
* - the host has not sent out anything (e.g. a passive server),
* - the Ack is outdated (packet with higher Ack number was received),
* - it is a bogus Ack (for a packet not sent on this connection).
*/
acked = tfrc_tx_hist_find_entry(hc->tx_hist, dccp_hdr_ack_seq(skb));
if (acked == NULL)
return;
/* For the sake of RTT sampling, ignore/remove all older entries */
tfrc_tx_hist_purge(&acked->next);
/* Update the moving average for the RTT estimate (RFC 3448, 4.3) */
now = ktime_get_real();
r_sample = dccp_sample_rtt(sk, ktime_us_delta(now, acked->stamp));
hc->tx_rtt = tfrc_ewma(hc->tx_rtt, r_sample, 9);
/*
* Update allowed sending rate X as per draft rfc3448bis-00, 4.2/3
*/
if (hc->tx_state == TFRC_SSTATE_NO_FBACK) {
ccid3_hc_tx_set_state(sk, TFRC_SSTATE_FBACK);
if (hc->tx_t_rto == 0) {
/*
* Initial feedback packet: Larger Initial Windows (4.2)
*/
hc->tx_x = rfc3390_initial_rate(sk);
hc->tx_t_ld = now;
ccid3_update_send_interval(hc);
goto done_computing_x;
} else if (hc->tx_p == 0) {
/*
* First feedback after nofeedback timer expiry (4.3)
*/
goto done_computing_x;
}
}
/* Update sending rate (step 4 of [RFC 3448, 4.3]) */
if (hc->tx_p > 0)
hc->tx_x_calc = tfrc_calc_x(hc->tx_s, hc->tx_rtt, hc->tx_p);
ccid3_hc_tx_update_x(sk, &now);
done_computing_x:
ccid3_pr_debug("%s(%p), RTT=%uus (sample=%uus), s=%u, "
"p=%u, X_calc=%u, X_recv=%u, X=%u\n",
dccp_role(sk), sk, hc->tx_rtt, r_sample,
hc->tx_s, hc->tx_p, hc->tx_x_calc,
(unsigned int)(hc->tx_x_recv >> 6),
(unsigned int)(hc->tx_x >> 6));
/* unschedule no feedback timer */
sk_stop_timer(sk, &hc->tx_no_feedback_timer);
/*
* As we have calculated new ipi, delta, t_nom it is possible
* that we now can send a packet, so wake up dccp_wait_for_ccid
*/
sk->sk_write_space(sk);
/*
* Update timeout interval for the nofeedback timer. In order to control
* rate halving on networks with very low RTTs (<= 1 ms), use per-route
* tunable RTAX_RTO_MIN value as the lower bound.
*/
hc->tx_t_rto = max_t(u32, 4 * hc->tx_rtt,
USEC_PER_SEC/HZ * tcp_rto_min(sk));
/*
* Schedule no feedback timer to expire in
* max(t_RTO, 2 * s/X) = max(t_RTO, 2 * t_ipi)
*/
t_nfb = max(hc->tx_t_rto, 2 * hc->tx_t_ipi);
ccid3_pr_debug("%s(%p), Scheduled no feedback timer to "
"expire in %lu jiffies (%luus)\n",
dccp_role(sk), sk, usecs_to_jiffies(t_nfb), t_nfb);
sk_reset_timer(sk, &hc->tx_no_feedback_timer,
jiffies + usecs_to_jiffies(t_nfb));
}
static int ccid3_hc_tx_parse_options(struct sock *sk, u8 packet_type,
u8 option, u8 *optval, u8 optlen)
{
struct ccid3_hc_tx_sock *hc = ccid3_hc_tx_sk(sk);
__be32 opt_val;
switch (option) {
case TFRC_OPT_RECEIVE_RATE:
case TFRC_OPT_LOSS_EVENT_RATE:
/* Must be ignored on Data packets, cf. RFC 4342 8.3 and 8.5 */
if (packet_type == DCCP_PKT_DATA)
break;
if (unlikely(optlen != 4)) {
DCCP_WARN("%s(%p), invalid len %d for %u\n",
dccp_role(sk), sk, optlen, option);
return -EINVAL;
}
opt_val = ntohl(get_unaligned((__be32 *)optval));
if (option == TFRC_OPT_RECEIVE_RATE) {
/* Receive Rate is kept in units of 64 bytes/second */
hc->tx_x_recv = opt_val;
hc->tx_x_recv <<= 6;
ccid3_pr_debug("%s(%p), RECEIVE_RATE=%u\n",
dccp_role(sk), sk, opt_val);
} else {
/* Update the fixpoint Loss Event Rate fraction */
hc->tx_p = tfrc_invert_loss_event_rate(opt_val);
ccid3_pr_debug("%s(%p), LOSS_EVENT_RATE=%u\n",
dccp_role(sk), sk, opt_val);
}
}
return 0;
}
static int ccid3_hc_tx_init(struct ccid *ccid, struct sock *sk)
{
struct ccid3_hc_tx_sock *hc = ccid_priv(ccid);
hc->tx_state = TFRC_SSTATE_NO_SENT;
hc->tx_hist = NULL;
setup_timer(&hc->tx_no_feedback_timer,
ccid3_hc_tx_no_feedback_timer, (unsigned long)sk);
return 0;
}
static void ccid3_hc_tx_exit(struct sock *sk)
{
struct ccid3_hc_tx_sock *hc = ccid3_hc_tx_sk(sk);
sk_stop_timer(sk, &hc->tx_no_feedback_timer);
tfrc_tx_hist_purge(&hc->tx_hist);
}
static void ccid3_hc_tx_get_info(struct sock *sk, struct tcp_info *info)
{
info->tcpi_rto = ccid3_hc_tx_sk(sk)->tx_t_rto;
info->tcpi_rtt = ccid3_hc_tx_sk(sk)->tx_rtt;
}
static int ccid3_hc_tx_getsockopt(struct sock *sk, const int optname, int len,
u32 __user *optval, int __user *optlen)
{
const struct ccid3_hc_tx_sock *hc = ccid3_hc_tx_sk(sk);
struct tfrc_tx_info tfrc;
const void *val;
switch (optname) {
case DCCP_SOCKOPT_CCID_TX_INFO:
if (len < sizeof(tfrc))
return -EINVAL;
memset(&tfrc, 0, sizeof(tfrc));
tfrc.tfrctx_x = hc->tx_x;
tfrc.tfrctx_x_recv = hc->tx_x_recv;
tfrc.tfrctx_x_calc = hc->tx_x_calc;
tfrc.tfrctx_rtt = hc->tx_rtt;
tfrc.tfrctx_p = hc->tx_p;
tfrc.tfrctx_rto = hc->tx_t_rto;
tfrc.tfrctx_ipi = hc->tx_t_ipi;
len = sizeof(tfrc);
val = &tfrc;
break;
default:
return -ENOPROTOOPT;
}
if (put_user(len, optlen) || copy_to_user(optval, val, len))
return -EFAULT;
return 0;
}
/*
* Receiver Half-Connection Routines
*/
/* CCID3 feedback types */
enum ccid3_fback_type {
CCID3_FBACK_NONE = 0,
CCID3_FBACK_INITIAL,
CCID3_FBACK_PERIODIC,
CCID3_FBACK_PARAM_CHANGE
};
#ifdef CONFIG_IP_DCCP_CCID3_DEBUG
static const char *ccid3_rx_state_name(enum ccid3_hc_rx_states state)
{
static const char *const ccid3_rx_state_names[] = {
[TFRC_RSTATE_NO_DATA] = "NO_DATA",
[TFRC_RSTATE_DATA] = "DATA",
};
return ccid3_rx_state_names[state];
}
#endif
static void ccid3_hc_rx_set_state(struct sock *sk,
enum ccid3_hc_rx_states state)
{
struct ccid3_hc_rx_sock *hc = ccid3_hc_rx_sk(sk);
enum ccid3_hc_rx_states oldstate = hc->rx_state;
ccid3_pr_debug("%s(%p) %-8.8s -> %s\n",
dccp_role(sk), sk, ccid3_rx_state_name(oldstate),
ccid3_rx_state_name(state));
WARN_ON(state == oldstate);
hc->rx_state = state;
}
static void ccid3_hc_rx_send_feedback(struct sock *sk,
const struct sk_buff *skb,
enum ccid3_fback_type fbtype)
{
struct ccid3_hc_rx_sock *hc = ccid3_hc_rx_sk(sk);
struct dccp_sock *dp = dccp_sk(sk);
ktime_t now = ktime_get_real();
s64 delta = 0;
switch (fbtype) {
case CCID3_FBACK_INITIAL:
hc->rx_x_recv = 0;
hc->rx_pinv = ~0U; /* see RFC 4342, 8.5 */
break;
case CCID3_FBACK_PARAM_CHANGE:
/*
* When parameters change (new loss or p > p_prev), we do not
* have a reliable estimate for R_m of [RFC 3448, 6.2] and so
* need to reuse the previous value of X_recv. However, when
* X_recv was 0 (due to early loss), this would kill X down to
* s/t_mbi (i.e. one packet in 64 seconds).
* To avoid such drastic reduction, we approximate X_recv as
* the number of bytes since last feedback.
* This is a safe fallback, since X is bounded above by X_calc.
*/
if (hc->rx_x_recv > 0)
break;
/* fall through */
case CCID3_FBACK_PERIODIC:
delta = ktime_us_delta(now, hc->rx_tstamp_last_feedback);
if (delta <= 0)
DCCP_BUG("delta (%ld) <= 0", (long)delta);
else
hc->rx_x_recv = scaled_div32(hc->rx_bytes_recv, delta);
break;
default:
return;
}
ccid3_pr_debug("Interval %ldusec, X_recv=%u, 1/p=%u\n", (long)delta,
hc->rx_x_recv, hc->rx_pinv);
hc->rx_tstamp_last_feedback = now;
hc->rx_last_counter = dccp_hdr(skb)->dccph_ccval;
hc->rx_bytes_recv = 0;
dp->dccps_hc_rx_insert_options = 1;
dccp_send_ack(sk);
}
static int ccid3_hc_rx_insert_options(struct sock *sk, struct sk_buff *skb)
{
const struct ccid3_hc_rx_sock *hc = ccid3_hc_rx_sk(sk);
__be32 x_recv, pinv;
if (!(sk->sk_state == DCCP_OPEN || sk->sk_state == DCCP_PARTOPEN))
return 0;
if (dccp_packet_without_ack(skb))
return 0;
x_recv = htonl(hc->rx_x_recv);
pinv = htonl(hc->rx_pinv);
if (dccp_insert_option(skb, TFRC_OPT_LOSS_EVENT_RATE,
&pinv, sizeof(pinv)) ||
dccp_insert_option(skb, TFRC_OPT_RECEIVE_RATE,
&x_recv, sizeof(x_recv)))
return -1;
return 0;
}
/**
* ccid3_first_li - Implements [RFC 5348, 6.3.1]
*
* Determine the length of the first loss interval via inverse lookup.
* Assume that X_recv can be computed by the throughput equation
* s
* X_recv = --------
* R * fval
* Find some p such that f(p) = fval; return 1/p (scaled).
*/
static u32 ccid3_first_li(struct sock *sk)
{
struct ccid3_hc_rx_sock *hc = ccid3_hc_rx_sk(sk);
u32 x_recv, p, delta;
u64 fval;
if (hc->rx_rtt == 0) {
DCCP_WARN("No RTT estimate available, using fallback RTT\n");
hc->rx_rtt = DCCP_FALLBACK_RTT;
}
delta = ktime_to_us(net_timedelta(hc->rx_tstamp_last_feedback));
x_recv = scaled_div32(hc->rx_bytes_recv, delta);
if (x_recv == 0) { /* would also trigger divide-by-zero */
DCCP_WARN("X_recv==0\n");
if (hc->rx_x_recv == 0) {
DCCP_BUG("stored value of X_recv is zero");
return ~0U;
}
x_recv = hc->rx_x_recv;
}
fval = scaled_div(hc->rx_s, hc->rx_rtt);
fval = scaled_div32(fval, x_recv);
p = tfrc_calc_x_reverse_lookup(fval);
ccid3_pr_debug("%s(%p), receive rate=%u bytes/s, implied "
"loss rate=%u\n", dccp_role(sk), sk, x_recv, p);
return p == 0 ? ~0U : scaled_div(1, p);
}
static void ccid3_hc_rx_packet_recv(struct sock *sk, struct sk_buff *skb)
{
struct ccid3_hc_rx_sock *hc = ccid3_hc_rx_sk(sk);
enum ccid3_fback_type do_feedback = CCID3_FBACK_NONE;
const u64 ndp = dccp_sk(sk)->dccps_options_received.dccpor_ndp;
const bool is_data_packet = dccp_data_packet(skb);
if (unlikely(hc->rx_state == TFRC_RSTATE_NO_DATA)) {
if (is_data_packet) {
const u32 payload = skb->len - dccp_hdr(skb)->dccph_doff * 4;
do_feedback = CCID3_FBACK_INITIAL;
ccid3_hc_rx_set_state(sk, TFRC_RSTATE_DATA);
hc->rx_s = payload;
/*
* Not necessary to update rx_bytes_recv here,
* since X_recv = 0 for the first feedback packet (cf.
* RFC 3448, 6.3) -- gerrit
*/
}
goto update_records;
}
if (tfrc_rx_hist_duplicate(&hc->rx_hist, skb))
return; /* done receiving */
if (is_data_packet) {
const u32 payload = skb->len - dccp_hdr(skb)->dccph_doff * 4;
/*
* Update moving-average of s and the sum of received payload bytes
*/
hc->rx_s = tfrc_ewma(hc->rx_s, payload, 9);
hc->rx_bytes_recv += payload;
}
/*
* Perform loss detection and handle pending losses
*/
if (tfrc_rx_handle_loss(&hc->rx_hist, &hc->rx_li_hist,
skb, ndp, ccid3_first_li, sk)) {
do_feedback = CCID3_FBACK_PARAM_CHANGE;
goto done_receiving;
}
if (tfrc_rx_hist_loss_pending(&hc->rx_hist))
return; /* done receiving */
/*
* Handle data packets: RTT sampling and monitoring p
*/
if (unlikely(!is_data_packet))
goto update_records;
if (!tfrc_lh_is_initialised(&hc->rx_li_hist)) {
const u32 sample = tfrc_rx_hist_sample_rtt(&hc->rx_hist, skb);
/*
* Empty loss history: no loss so far, hence p stays 0.
* Sample RTT values, since an RTT estimate is required for the
* computation of p when the first loss occurs; RFC 3448, 6.3.1.
*/
if (sample != 0)
hc->rx_rtt = tfrc_ewma(hc->rx_rtt, sample, 9);
} else if (tfrc_lh_update_i_mean(&hc->rx_li_hist, skb)) {
/*
* Step (3) of [RFC 3448, 6.1]: Recompute I_mean and, if I_mean
* has decreased (resp. p has increased), send feedback now.
*/
do_feedback = CCID3_FBACK_PARAM_CHANGE;
}
/*
* Check if the periodic once-per-RTT feedback is due; RFC 4342, 10.3
*/
if (SUB16(dccp_hdr(skb)->dccph_ccval, hc->rx_last_counter) > 3)
do_feedback = CCID3_FBACK_PERIODIC;
update_records:
tfrc_rx_hist_add_packet(&hc->rx_hist, skb, ndp);
done_receiving:
if (do_feedback)
ccid3_hc_rx_send_feedback(sk, skb, do_feedback);
}
static int ccid3_hc_rx_init(struct ccid *ccid, struct sock *sk)
{
struct ccid3_hc_rx_sock *hc = ccid_priv(ccid);
hc->rx_state = TFRC_RSTATE_NO_DATA;
tfrc_lh_init(&hc->rx_li_hist);
return tfrc_rx_hist_alloc(&hc->rx_hist);
}
static void ccid3_hc_rx_exit(struct sock *sk)
{
struct ccid3_hc_rx_sock *hc = ccid3_hc_rx_sk(sk);
tfrc_rx_hist_purge(&hc->rx_hist);
tfrc_lh_cleanup(&hc->rx_li_hist);
}
static void ccid3_hc_rx_get_info(struct sock *sk, struct tcp_info *info)
{
info->tcpi_ca_state = ccid3_hc_rx_sk(sk)->rx_state;
info->tcpi_options |= TCPI_OPT_TIMESTAMPS;
info->tcpi_rcv_rtt = ccid3_hc_rx_sk(sk)->rx_rtt;
}
static int ccid3_hc_rx_getsockopt(struct sock *sk, const int optname, int len,
u32 __user *optval, int __user *optlen)
{
const struct ccid3_hc_rx_sock *hc = ccid3_hc_rx_sk(sk);
struct tfrc_rx_info rx_info;
const void *val;
switch (optname) {
case DCCP_SOCKOPT_CCID_RX_INFO:
if (len < sizeof(rx_info))
return -EINVAL;
rx_info.tfrcrx_x_recv = hc->rx_x_recv;
rx_info.tfrcrx_rtt = hc->rx_rtt;
rx_info.tfrcrx_p = tfrc_invert_loss_event_rate(hc->rx_pinv);
len = sizeof(rx_info);
val = &rx_info;
break;
default:
return -ENOPROTOOPT;
}
if (put_user(len, optlen) || copy_to_user(optval, val, len))
return -EFAULT;
return 0;
}
struct ccid_operations ccid3_ops = {
.ccid_id = DCCPC_CCID3,
.ccid_name = "TCP-Friendly Rate Control",
.ccid_hc_tx_obj_size = sizeof(struct ccid3_hc_tx_sock),
.ccid_hc_tx_init = ccid3_hc_tx_init,
.ccid_hc_tx_exit = ccid3_hc_tx_exit,
.ccid_hc_tx_send_packet = ccid3_hc_tx_send_packet,
.ccid_hc_tx_packet_sent = ccid3_hc_tx_packet_sent,
.ccid_hc_tx_packet_recv = ccid3_hc_tx_packet_recv,
.ccid_hc_tx_parse_options = ccid3_hc_tx_parse_options,
.ccid_hc_rx_obj_size = sizeof(struct ccid3_hc_rx_sock),
.ccid_hc_rx_init = ccid3_hc_rx_init,
.ccid_hc_rx_exit = ccid3_hc_rx_exit,
.ccid_hc_rx_insert_options = ccid3_hc_rx_insert_options,
.ccid_hc_rx_packet_recv = ccid3_hc_rx_packet_recv,
.ccid_hc_rx_get_info = ccid3_hc_rx_get_info,
.ccid_hc_tx_get_info = ccid3_hc_tx_get_info,
.ccid_hc_rx_getsockopt = ccid3_hc_rx_getsockopt,
.ccid_hc_tx_getsockopt = ccid3_hc_tx_getsockopt,
};
#ifdef CONFIG_IP_DCCP_CCID3_DEBUG
module_param(ccid3_debug, bool, 0644);
MODULE_PARM_DESC(ccid3_debug, "Enable CCID-3 debug messages");
#endif
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