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Subject[PATCH v7 7/7] TCPCT part 2g: parse cookie pair and 64-bit timestamp
Every bit is sacred.  Use as few bits as possible in tcp_options_received.
Group related timestamp flag bits for cache line memory efficiency.

Fix #define spacing for TCP options.

Define and parse 64-bit timestamp extended option (and minor cleanup).
However, only 32-bits are used at this time (permitted by specification).

Parse cookie pair extended option (previously defined).

Handle header extension.

Fix initialization in tcp_minisocks.

Requires:
net: tcp_header_len_th and tcp_option_len_th
TCPCT part 2f: cleanup tcp_parse_options

Signed-off-by: William.Allen.Simpson@gmail.com
---
include/linux/tcp.h | 12 ++++-
include/net/tcp.h | 45 +++++++++--------
net/ipv4/tcp_input.c | 123 ++++++++++++++++++++++++++++++++++++++++++----
net/ipv4/tcp_minisocks.c | 6 ++
4 files changed, 152 insertions(+), 34 deletions(-)diff --git a/include/linux/tcp.h b/include/linux/tcp.h
index 2987ee8..05fa9b2 100644
--- a/include/linux/tcp.h
+++ b/include/linux/tcp.h
@@ -247,7 +247,7 @@ struct tcp_options_received {
u32 ts_recent; /* Time stamp to echo next */
u32 rcv_tsval; /* Time stamp value */
u32 rcv_tsecr; /* Time stamp echo reply */
- u16 saw_tstamp : 1, /* Saw TIMESTAMP on last packet */
+ u16 tstamp64_ok:1, /* Verified with cookie pair */
tstamp_ok : 1, /* TIMESTAMP seen on SYN packet */
dsack : 1, /* D-SACK is scheduled */
wscale_ok : 1, /* Wscale seen on SYN packet */
@@ -260,13 +260,21 @@ struct tcp_options_received {
u8 num_sacks; /* Number of SACK blocks */
u16 user_mss; /* mss requested by user in ioctl */
u16 mss_clamp; /* Maximal mss, negotiated at connection setup */
+
+ /* When the options are extended beyond the standard 40 bytes,
+ * this holds the additional data offset (up to 1,020 bytes).
+ */
+ u8 extended; /* in 32-bit words */
+ u8 saw_tstamp64:1, /* 64-bit TIMESTAMP seen on last packet */
+ saw_tstamp:1, /* TIMESTAMP seen on last packet */
+ __unused:6;
};

static inline void tcp_clear_options(struct tcp_options_received *rx_opt)
{
+ rx_opt->tstamp64_ok = 0;
rx_opt->tstamp_ok = rx_opt->sack_ok = 0;
rx_opt->wscale_ok = rx_opt->snd_wscale = 0;
- rx_opt->cookie_plus = 0;
}

/* This is the max number of SACKS that we'll generate and process. It's safe
diff --git a/include/net/tcp.h b/include/net/tcp.h
index 420e872..4b560d2 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -156,9 +156,8 @@ extern void tcp_time_wait(struct sock *sk, int state, int timeo);
/*
* TCP option
*/
-
-#define TCPOPT_NOP 1 /* Padding */
#define TCPOPT_EOL 0 /* End of options */
+#define TCPOPT_NOP 1 /* Padding */
#define TCPOPT_MSS 2 /* Segment size negotiating */
#define TCPOPT_WINDOW 3 /* Window scaling */
#define TCPOPT_SACK_PERM 4 /* SACK Permitted */
@@ -166,30 +165,32 @@ extern void tcp_time_wait(struct sock *sk, int state, int timeo);
#define TCPOPT_TIMESTAMP 8 /* Better RTT estimations/PAWS */
#define TCPOPT_MD5SIG 19 /* MD5 Signature (RFC2385) */
#define TCPOPT_COOKIE 253 /* Cookie extension (experimental) */
-
-/*
- * TCP option lengths
- */
-
-#define TCPOLEN_MSS 4
-#define TCPOLEN_WINDOW 3
-#define TCPOLEN_SACK_PERM 2
-#define TCPOLEN_TIMESTAMP 10
-#define TCPOLEN_MD5SIG 18
-#define TCPOLEN_COOKIE_BASE 2 /* Cookie-less header extension */
-#define TCPOLEN_COOKIE_PAIR 3 /* Cookie pair header extension */
-#define TCPOLEN_COOKIE_MIN (TCPOLEN_COOKIE_BASE+TCP_COOKIE_MIN)
-#define TCPOLEN_COOKIE_MAX (TCPOLEN_COOKIE_BASE+TCP_COOKIE_MAX)
-
-/* But this is what stacks really send out. */
-#define TCPOLEN_TSTAMP_ALIGNED 12
+#define TCPOPT_TSTAMP64 254 /* 64-bit extension (experimental) */
+
+/* TCP option lengths (same order as above) */
+#define TCPOLEN_MSS 4
+#define TCPOLEN_WINDOW 3
+#define TCPOLEN_SACK_PERM 2
+#define TCPOLEN_SACK_BASE 2
+#define TCPOLEN_SACK_PERBLOCK 8
+#define TCPOLEN_TIMESTAMP 10
+#define TCPOLEN_MD5SIG 18
+#define TCPOLEN_COOKIE_BASE 2 /* Cookie-less header extension */
+#define TCPOLEN_COOKIE_PAIR 4 /* Cookie pair header extension */
+#define TCPOLEN_COOKIE_MIN (TCPOLEN_COOKIE_BASE+TCP_COOKIE_MIN)
+#define TCPOLEN_COOKIE_MAX (TCPOLEN_COOKIE_BASE+TCP_COOKIE_MAX)
+#define TCPOLEN_TSTAMP64 3
+
+/* TCP options 32-bit aligned (same order as above) */
+#define TCPOLEN_MSS_ALIGNED 4
#define TCPOLEN_WSCALE_ALIGNED 4
#define TCPOLEN_SACKPERM_ALIGNED 4
-#define TCPOLEN_SACK_BASE 2
#define TCPOLEN_SACK_BASE_ALIGNED 4
-#define TCPOLEN_SACK_PERBLOCK 8
+#define TCPOLEN_TSTAMP_ALIGNED 12
#define TCPOLEN_MD5SIG_ALIGNED 20
-#define TCPOLEN_MSS_ALIGNED 4
+
+/* TCP option extensions (same order as above) */
+#define TCPOEXT_TSTAMP64 16

/* Flags in tp->nonagle */
#define TCP_NAGLE_OFF 1 /* Nagle's algo is disabled */
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 2a9ef6b..dcad45b 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -3725,17 +3725,27 @@ old_ack:
/* Look for tcp options. Normally only called on SYN and SYNACK packets.
* But, this can also be called on packets in the established flow when
* the fast version below fails.
+ *
+ * Returns:
+ * 0 on success
+ * - on failure
*/
int tcp_parse_options(struct sk_buff *skb, const struct tcphdr *th,
struct tcp_options_received *opt_rx, u8 **hvpp, int estab)
{
+ __be32 *xdp = (__be32 *)th + th->doff;
unsigned char *ptr = (unsigned char *)(th + 1);
+ int remaining = skb_headlen(skb) - tcp_header_len_th(th);
int length = tcp_option_len_th(th);
+ int extend = 0;
bool syn = th->syn;

opt_rx->cookie_plus = 0;
+ opt_rx->extended = 0;
+ opt_rx->saw_tstamp64 = 0; /* false */
opt_rx->saw_tstamp = 0; /* false */

+repeat:
while (length > 0) {
int opsize;
int opcode = *ptr++;
@@ -3833,26 +3843,104 @@ int tcp_parse_options(struct sk_buff *skb, const struct tcphdr *th,
/* not yet implemented */
break;
case TCPOLEN_COOKIE_PAIR: {
- /* not yet implemented */
+ int words = ptr[1] & 0xf;
+
+ if (!syn &&
+ *ptr >= words &&
+ words >= (TCP_COOKIE_MIN / 4) &&
+ words <= (TCP_COOKIE_MAX / 4) &&
+ opt_rx->extended == 0) {
+ int bytes = words * 4;
+
+ opt_rx->extended = *ptr;
+ extend = *ptr * 4;
+
+ /* Adjust end_seq, set in
+ * tcp_v[4,6]_rcv()
+ */
+ TCP_SKB_CB(skb)->end_seq -= extend;
+ remaining -= extend;
+
+ if (unlikely(remaining < 0)) {
+ /* missing data!!! */
+ return remaining;
+ }
+ extend -= bytes;
+
+ opt_rx->cookie_plus = bytes
+ + TCPOLEN_COOKIE_BASE;
+ *hvpp = (u8 *)xdp;
+ xdp += words;
+ }
break;
}
case TCPOLEN_COOKIE_MIN+0:
case TCPOLEN_COOKIE_MIN+2:
case TCPOLEN_COOKIE_MIN+4:
case TCPOLEN_COOKIE_MIN+6:
- case TCPOLEN_COOKIE_MAX:
/* 16-bit multiple */
if (syn) {
opt_rx->cookie_plus = opsize;
*hvpp = ptr;
}
break;
+ case TCPOLEN_COOKIE_MAX+0:
+ /* either cookie or cookie pair */
+ if (syn || opt_rx->saw_tstamp64) {
+ opt_rx->cookie_plus = opsize;
+ *hvpp = ptr;
+ }
+ break;
+ case TCPOLEN_COOKIE_MAX+4:
+ case TCPOLEN_COOKIE_MAX+8:
+ case TCPOLEN_COOKIE_MAX+12:
+ case TCPOLEN_COOKIE_MAX+TCP_COOKIE_MAX:
+ /* 32-bit multiple (pair) */
+ if (opt_rx->saw_tstamp64) {
+ opt_rx->cookie_plus = opsize;
+ *hvpp = ptr;
+ }
+ break;
default:
/* ignore option */
break;
};
break;

+ case TCPOPT_TSTAMP64:
+ if (opsize == TCPOLEN_TSTAMP64) {
+ if (!syn &&
+ *ptr >= (TCPOEXT_TSTAMP64 / 4) &&
+ !opt_rx->saw_tstamp &&
+ opt_rx->extended == 0) {
+ opt_rx->extended = *ptr;
+ extend = *ptr * 4;
+
+ /* Adjust end_seq, set in
+ * tcp_v[4,6]_rcv()
+ */
+ TCP_SKB_CB(skb)->end_seq -= extend;
+ remaining -= extend;
+
+ if (unlikely(remaining < 0)) {
+ /* missing data!!! */
+ return remaining;
+ }
+ extend -= TCPOEXT_TSTAMP64;
+
+ /* 64-bits not yet implemented */
+ xdp++;
+ opt_rx->rcv_tsval = ntohl(*xdp);
+ xdp += 2;
+ opt_rx->rcv_tsecr = ntohl(*xdp);
+ xdp++;
+
+ opt_rx->saw_tstamp64 = 1; /* true */
+ opt_rx->saw_tstamp = 1; /* true */
+ }
+ }
+ break;
+
default:
/* skip unrecognized options */
break;
@@ -3861,6 +3949,13 @@ int tcp_parse_options(struct sk_buff *skb, const struct tcphdr *th,
ptr += opsize - 2;
length -= opsize;
}
+
+ if (unlikely(extend > 0)) {
+ ptr = (unsigned char *)xdp;
+ length = extend;
+ extend = 0;
+ goto repeat;
+ }
return 0;
}

@@ -3887,6 +3982,11 @@ static int tcp_parse_aligned_timestamp(struct tcp_sock *tp, struct tcphdr *th)

/* Fast parse options. This hopes to only see timestamps.
* If it is wrong it falls back on tcp_parse_options().
+ *
+ * Returns:
+ * 1 on success, fast
+ * 0 on success, slow
+ * - on failure
*/
static int tcp_fast_parse_options(struct sk_buff *skb, struct tcphdr *th,
struct tcp_sock *tp, u8 **hvpp)
@@ -3896,11 +3996,14 @@ static int tcp_fast_parse_options(struct sk_buff *skb, struct tcphdr *th,
*/
if (th->doff == (sizeof(*th) / 4)) {
tp->rx_opt.saw_tstamp = 0;
+ tp->rx_opt.extended = 0;
return 0;
- } else if (tp->rx_opt.tstamp_ok &&
- th->doff == ((sizeof(*th) + TCPOLEN_TSTAMP_ALIGNED) / 4)) {
- if (tcp_parse_aligned_timestamp(tp, th))
- return 1;
+ }
+ if (th->doff == ((sizeof(*th) + TCPOLEN_TSTAMP_ALIGNED) / 4) &&
+ tp->rx_opt.tstamp_ok &&
+ tcp_parse_aligned_timestamp(tp, th)) {
+ tp->rx_opt.extended = 0;
+ return 1;
}
return tcp_parse_options(skb, th, &tp->rx_opt, hvpp, 1);
}
@@ -3911,8 +4014,8 @@ static int tcp_fast_parse_options(struct sk_buff *skb, struct tcphdr *th,
*/
u8 *tcp_parse_md5sig_option(struct tcphdr *th)
{
- int length = (th->doff << 2) - sizeof (*th);
u8 *ptr = (u8*)(th + 1);
+ int length = tcp_option_len_th(th);

/* If the TCP option is too short, we can short cut */
if (length < TCPOLEN_MD5SIG)
@@ -4377,7 +4480,7 @@ static void tcp_data_queue(struct sock *sk, struct sk_buff *skb)
if (TCP_SKB_CB(skb)->seq == TCP_SKB_CB(skb)->end_seq)
goto drop;

- __skb_pull(skb, th->doff * 4);
+ __skb_pull(skb, (th->doff + tp->rx_opt.extended) * 4);

TCP_ECN_accept_cwr(tp, skb);

@@ -5038,8 +5141,8 @@ static void tcp_urg(struct sock *sk, struct sk_buff *skb, struct tcphdr *th)

/* Do we wait for any urgent data? - normally not... */
if (tp->urg_data == TCP_URG_NOTYET) {
- u32 ptr = tp->urg_seq - ntohl(th->seq) + (th->doff * 4) -
- th->syn;
+ u32 ptr = ((th->doff + tp->rx_opt.extended) * 4)
+ + tp->urg_seq - ntohl(th->seq) - th->syn;

/* Is the urgent pointer pointing into this packet? */
if (ptr < skb->len) {
diff --git a/net/ipv4/tcp_minisocks.c b/net/ipv4/tcp_minisocks.c
index 0f1b409..2240012 100644
--- a/net/ipv4/tcp_minisocks.c
+++ b/net/ipv4/tcp_minisocks.c
@@ -109,6 +109,9 @@ tcp_timewait_state_process(struct inet_timewait_sock *tw, struct sk_buff *skb,
}
} else {
/* otherwise initialized by tcp_parse_options() */
+ tmp_opt.cookie_plus = 0;
+ tmp_opt.extended = 0;
+ tmp_opt.saw_tstamp64 = 0; /* false */
tmp_opt.saw_tstamp = 0; /* false */
}

@@ -550,6 +553,9 @@ struct sock *tcp_check_req(struct sock *sk, struct sk_buff *skb,
}
} else {
/* otherwise initialized by tcp_parse_options() */
+ tmp_opt.cookie_plus = 0;
+ tmp_opt.extended = 0;
+ tmp_opt.saw_tstamp64 = 0; /* false */
tmp_opt.saw_tstamp = 0; /* false */
}

--
1.6.3.3
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