Parse incoming TCP_COOKIE option(s).
Calculate <SYN,ACK> TCP_COOKIE option.
Send optional <SYN,ACK> data.
This is a significantly revised implementation of an earlier (year-old)
patch that no longer applies cleanly, with permission of the original
author (Adam Langley):
http://thread.gmane.org/gmane.linux.network/102586
Requires:
TCPCT part 1a: add request_values parameter for sending SYNACK
TCPCT part 1b: generate Responder Cookie secret
TCPCT part 1c: sysctl_tcp_cookie_size, socket option TCP_COOKIE_TRANSACTIONS
TCPCT part 1d: define TCP cookie option, extend existing struct's
TCPCT part 1e: implement socket option TCP_COOKIE_TRANSACTIONS
TCPCT part 1f: Initiator Cookie => Responder
Signed-off-by: William.Allen.Simpson@gmail.com
Signed-off-by: David S. Miller <davem@davemloft.net>
extern void tcp_parse_options(struct sk_buff *skb,
struct tcp_options_received *opt_rx,
+ u8 **hvpp,
int estab,
struct dst_entry *dst);
struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb,
struct ip_options *opt)
{
+ struct tcp_options_received tcp_opt;
+ u8 *hash_location;
struct inet_request_sock *ireq;
struct tcp_request_sock *treq;
struct tcp_sock *tp = tcp_sk(sk);
int mss;
struct rtable *rt;
__u8 rcv_wscale;
- struct tcp_options_received tcp_opt;
if (!sysctl_tcp_syncookies || !th->ack)
goto out;
/* check for timestamp cookie support */
memset(&tcp_opt, 0, sizeof(tcp_opt));
- tcp_parse_options(skb, &tcp_opt, 0, &rt->u.dst);
+ tcp_parse_options(skb, &tcp_opt, &hash_location, 0, &rt->u.dst);
if (tcp_opt.saw_tstamp)
cookie_check_timestamp(&tcp_opt);
* the fast version below fails.
*/
void tcp_parse_options(struct sk_buff *skb, struct tcp_options_received *opt_rx,
- int estab, struct dst_entry *dst)
+ u8 **hvpp, int estab, struct dst_entry *dst)
{
unsigned char *ptr;
struct tcphdr *th = tcp_hdr(skb);
*/
break;
#endif
- }
+ case TCPOPT_COOKIE:
+ /* This option is variable length.
+ */
+ switch (opsize) {
+ case TCPOLEN_COOKIE_BASE:
+ /* not yet implemented */
+ break;
+ case TCPOLEN_COOKIE_PAIR:
+ /* not yet implemented */
+ 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 */
+ opt_rx->cookie_plus = opsize;
+ *hvpp = ptr;
+ default:
+ /* ignore option */
+ break;
+ };
+ break;
+ };
ptr += opsize-2;
length -= opsize;
* If it is wrong it falls back on tcp_parse_options().
*/
static int tcp_fast_parse_options(struct sk_buff *skb, struct tcphdr *th,
- struct tcp_sock *tp)
+ struct tcp_sock *tp, u8 **hvpp)
{
- if (th->doff == sizeof(struct tcphdr) >> 2) {
+ /* In the spirit of fast parsing, compare doff directly to constant
+ * values. Because equality is used, short doff can be ignored here.
+ */
+ if (th->doff == (sizeof(*th) / 4)) {
tp->rx_opt.saw_tstamp = 0;
return 0;
} else if (tp->rx_opt.tstamp_ok &&
- th->doff == (sizeof(struct tcphdr)>>2)+(TCPOLEN_TSTAMP_ALIGNED>>2)) {
+ th->doff == ((sizeof(*th) + TCPOLEN_TSTAMP_ALIGNED) / 4)) {
if (tcp_parse_aligned_timestamp(tp, th))
return 1;
}
- tcp_parse_options(skb, &tp->rx_opt, 1, NULL);
+ tcp_parse_options(skb, &tp->rx_opt, hvpp, 1, NULL);
return 1;
}
static int tcp_validate_incoming(struct sock *sk, struct sk_buff *skb,
struct tcphdr *th, int syn_inerr)
{
+ u8 *hash_location;
struct tcp_sock *tp = tcp_sk(sk);
/* RFC1323: H1. Apply PAWS check first. */
- if (tcp_fast_parse_options(skb, th, tp) && tp->rx_opt.saw_tstamp &&
+ if (tcp_fast_parse_options(skb, th, tp, &hash_location) &&
+ tp->rx_opt.saw_tstamp &&
tcp_paws_discard(sk, skb)) {
if (!th->rst) {
NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_PAWSESTABREJECTED);
static int tcp_rcv_synsent_state_process(struct sock *sk, struct sk_buff *skb,
struct tcphdr *th, unsigned len)
{
- struct tcp_sock *tp = tcp_sk(sk);
+ u8 *hash_location;
struct inet_connection_sock *icsk = inet_csk(sk);
- int saved_clamp = tp->rx_opt.mss_clamp;
+ struct tcp_sock *tp = tcp_sk(sk);
struct dst_entry *dst = __sk_dst_get(sk);
+ struct tcp_cookie_values *cvp = tp->cookie_values;
+ int saved_clamp = tp->rx_opt.mss_clamp;
- tcp_parse_options(skb, &tp->rx_opt, 0, dst);
+ tcp_parse_options(skb, &tp->rx_opt, &hash_location, 0, dst);
if (th->ack) {
/* rfc793:
* Change state from SYN-SENT only after copied_seq
* is initialized. */
tp->copied_seq = tp->rcv_nxt;
+
+ if (cvp != NULL &&
+ cvp->cookie_pair_size > 0 &&
+ tp->rx_opt.cookie_plus > 0) {
+ int cookie_size = tp->rx_opt.cookie_plus
+ - TCPOLEN_COOKIE_BASE;
+ int cookie_pair_size = cookie_size
+ + cvp->cookie_desired;
+
+ /* A cookie extension option was sent and returned.
+ * Note that each incoming SYNACK replaces the
+ * Responder cookie. The initial exchange is most
+ * fragile, as protection against spoofing relies
+ * entirely upon the sequence and timestamp (above).
+ * This replacement strategy allows the correct pair to
+ * pass through, while any others will be filtered via
+ * Responder verification later.
+ */
+ if (sizeof(cvp->cookie_pair) >= cookie_pair_size) {
+ memcpy(&cvp->cookie_pair[cvp->cookie_desired],
+ hash_location, cookie_size);
+ cvp->cookie_pair_size = cookie_pair_size;
+ }
+ }
+
smp_mb();
tcp_set_state(sk, TCP_ESTABLISHED);
int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb)
{
+ struct tcp_extend_values tmp_ext;
struct tcp_options_received tmp_opt;
+ u8 *hash_location;
struct request_sock *req;
struct inet_request_sock *ireq;
+ struct tcp_sock *tp = tcp_sk(sk);
struct dst_entry *dst = NULL;
__be32 saddr = ip_hdr(skb)->saddr;
__be32 daddr = ip_hdr(skb)->daddr;
tcp_clear_options(&tmp_opt);
tmp_opt.mss_clamp = TCP_MSS_DEFAULT;
- tmp_opt.user_mss = tcp_sk(sk)->rx_opt.user_mss;
+ tmp_opt.user_mss = tp->rx_opt.user_mss;
+ tcp_parse_options(skb, &tmp_opt, &hash_location, 0, dst);
+
+ if (tmp_opt.cookie_plus > 0 &&
+ tmp_opt.saw_tstamp &&
+ !tp->rx_opt.cookie_out_never &&
+ (sysctl_tcp_cookie_size > 0 ||
+ (tp->cookie_values != NULL &&
+ tp->cookie_values->cookie_desired > 0))) {
+ u8 *c;
+ u32 *mess = &tmp_ext.cookie_bakery[COOKIE_DIGEST_WORDS];
+ int l = tmp_opt.cookie_plus - TCPOLEN_COOKIE_BASE;
+
+ if (tcp_cookie_generator(&tmp_ext.cookie_bakery[0]) != 0)
+ goto drop_and_release;
+
+ /* Secret recipe starts with IP addresses */
+ *mess++ ^= daddr;
+ *mess++ ^= saddr;
- tcp_parse_options(skb, &tmp_opt, 0, dst);
+ /* plus variable length Initiator Cookie */
+ c = (u8 *)mess;
+ while (l-- > 0)
+ *c++ ^= *hash_location++;
+
+#ifdef CONFIG_SYN_COOKIES
+ want_cookie = 0; /* not our kind of cookie */
+#endif
+ tmp_ext.cookie_out_never = 0; /* false */
+ tmp_ext.cookie_plus = tmp_opt.cookie_plus;
+ } else if (!tp->rx_opt.cookie_in_always) {
+ /* redundant indications, but ensure initialization. */
+ tmp_ext.cookie_out_never = 1; /* true */
+ tmp_ext.cookie_plus = 0;
+ } else {
+ goto drop_and_release;
+ }
+ tmp_ext.cookie_in_always = tp->rx_opt.cookie_in_always;
if (want_cookie && !tmp_opt.saw_tstamp)
tcp_clear_options(&tmp_opt);
tmp_opt.tstamp_ok = tmp_opt.saw_tstamp;
-
tcp_openreq_init(req, &tmp_opt, skb);
if (security_inet_conn_request(sk, skb, req))
}
tcp_rsk(req)->snt_isn = isn;
- if (__tcp_v4_send_synack(sk, dst, req, NULL) || want_cookie)
+ if (__tcp_v4_send_synack(sk, dst, req,
+ (struct request_values *)&tmp_ext) ||
+ want_cookie)
goto drop_and_free;
inet_csk_reqsk_queue_hash_add(sk, req, TCP_TIMEOUT_INIT);
tcp_timewait_state_process(struct inet_timewait_sock *tw, struct sk_buff *skb,
const struct tcphdr *th)
{
- struct tcp_timewait_sock *tcptw = tcp_twsk((struct sock *)tw);
struct tcp_options_received tmp_opt;
+ u8 *hash_location;
+ struct tcp_timewait_sock *tcptw = tcp_twsk((struct sock *)tw);
int paws_reject = 0;
if (th->doff > (sizeof(*th) >> 2) && tcptw->tw_ts_recent_stamp) {
tmp_opt.tstamp_ok = 1;
- tcp_parse_options(skb, &tmp_opt, 1, NULL);
+ tcp_parse_options(skb, &tmp_opt, &hash_location, 1, NULL);
if (tmp_opt.saw_tstamp) {
tmp_opt.ts_recent = tcptw->tw_ts_recent;
struct request_sock *req,
struct request_sock **prev)
{
+ struct tcp_options_received tmp_opt;
+ u8 *hash_location;
+ struct sock *child;
const struct tcphdr *th = tcp_hdr(skb);
__be32 flg = tcp_flag_word(th) & (TCP_FLAG_RST|TCP_FLAG_SYN|TCP_FLAG_ACK);
int paws_reject = 0;
- struct tcp_options_received tmp_opt;
- struct sock *child;
- if ((th->doff > (sizeof(struct tcphdr)>>2)) && (req->ts_recent)) {
+ if ((th->doff > (sizeof(*th) >> 2)) && (req->ts_recent)) {
tmp_opt.tstamp_ok = 1;
- tcp_parse_options(skb, &tmp_opt, 1, NULL);
+ tcp_parse_options(skb, &tmp_opt, &hash_location, 1, NULL);
if (tmp_opt.saw_tstamp) {
tmp_opt.ts_recent = req->ts_recent;
struct request_sock *req,
unsigned mss, struct sk_buff *skb,
struct tcp_out_options *opts,
- struct tcp_md5sig_key **md5) {
- unsigned size = 0;
+ struct tcp_md5sig_key **md5,
+ struct tcp_extend_values *xvp)
+{
struct inet_request_sock *ireq = inet_rsk(req);
- char doing_ts;
+ unsigned remaining = MAX_TCP_OPTION_SPACE;
+ u8 cookie_plus = (xvp != NULL && !xvp->cookie_out_never) ?
+ xvp->cookie_plus :
+ 0;
+ bool doing_ts = ireq->tstamp_ok;
#ifdef CONFIG_TCP_MD5SIG
*md5 = tcp_rsk(req)->af_specific->md5_lookup(sk, req);
if (*md5) {
opts->options |= OPTION_MD5;
- size += TCPOLEN_MD5SIG_ALIGNED;
+ remaining -= TCPOLEN_MD5SIG_ALIGNED;
+
+ /* We can't fit any SACK blocks in a packet with MD5 + TS
+ * options. There was discussion about disabling SACK
+ * rather than TS in order to fit in better with old,
+ * buggy kernels, but that was deemed to be unnecessary.
+ */
+ doing_ts &= !ireq->sack_ok;
}
#else
*md5 = NULL;
#endif
- /* we can't fit any SACK blocks in a packet with MD5 + TS
- options. There was discussion about disabling SACK rather than TS in
- order to fit in better with old, buggy kernels, but that was deemed
- to be unnecessary. */
- doing_ts = ireq->tstamp_ok && !(*md5 && ireq->sack_ok);
-
+ /* We always send an MSS option. */
opts->mss = mss;
- size += TCPOLEN_MSS_ALIGNED;
+ remaining -= TCPOLEN_MSS_ALIGNED;
if (likely(ireq->wscale_ok)) {
opts->ws = ireq->rcv_wscale;
opts->options |= OPTION_WSCALE;
- size += TCPOLEN_WSCALE_ALIGNED;
+ remaining -= TCPOLEN_WSCALE_ALIGNED;
}
if (likely(doing_ts)) {
opts->options |= OPTION_TS;
opts->tsval = TCP_SKB_CB(skb)->when;
opts->tsecr = req->ts_recent;
- size += TCPOLEN_TSTAMP_ALIGNED;
+ remaining -= TCPOLEN_TSTAMP_ALIGNED;
}
if (likely(ireq->sack_ok)) {
opts->options |= OPTION_SACK_ADVERTISE;
if (unlikely(!doing_ts))
- size += TCPOLEN_SACKPERM_ALIGNED;
+ remaining -= TCPOLEN_SACKPERM_ALIGNED;
}
- return size;
+ /* Similar rationale to tcp_syn_options() applies here, too.
+ * If the <SYN> options fit, the same options should fit now!
+ */
+ if (*md5 == NULL &&
+ doing_ts &&
+ cookie_plus > TCPOLEN_COOKIE_BASE) {
+ int need = cookie_plus; /* has TCPOLEN_COOKIE_BASE */
+
+ if (0x2 & need) {
+ /* 32-bit multiple */
+ need += 2; /* NOPs */
+ }
+ if (need <= remaining) {
+ opts->options |= OPTION_COOKIE_EXTENSION;
+ opts->hash_size = cookie_plus - TCPOLEN_COOKIE_BASE;
+ remaining -= need;
+ } else {
+ /* There's no error return, so flag it. */
+ xvp->cookie_out_never = 1; /* true */
+ opts->hash_size = 0;
+ }
+ }
+ return MAX_TCP_OPTION_SPACE - remaining;
}
/* Compute TCP options for ESTABLISHED sockets. This is not the
struct request_values *rvp)
{
struct tcp_out_options opts;
+ struct tcp_extend_values *xvp = tcp_xv(rvp);
struct inet_request_sock *ireq = inet_rsk(req);
struct tcp_sock *tp = tcp_sk(sk);
struct tcphdr *th;
#endif
TCP_SKB_CB(skb)->when = tcp_time_stamp;
tcp_header_size = tcp_synack_options(sk, req, mss,
- skb, &opts, &md5) +
- sizeof(struct tcphdr);
+ skb, &opts, &md5, xvp)
+ + sizeof(*th);
skb_push(skb, tcp_header_size);
skb_reset_transport_header(skb);
*/
tcp_init_nondata_skb(skb, tcp_rsk(req)->snt_isn,
TCPCB_FLAG_SYN | TCPCB_FLAG_ACK);
+
+ if (OPTION_COOKIE_EXTENSION & opts.options) {
+ const struct tcp_cookie_values *cvp = tp->cookie_values;
+
+ if (cvp != NULL &&
+ cvp->s_data_constant &&
+ cvp->s_data_desired > 0) {
+ u8 *buf = skb_put(skb, cvp->s_data_desired);
+
+ /* copy data directly from the listening socket. */
+ memcpy(buf, cvp->s_data_payload, cvp->s_data_desired);
+ TCP_SKB_CB(skb)->end_seq += cvp->s_data_desired;
+ }
+
+ if (opts.hash_size > 0) {
+ __u32 workspace[SHA_WORKSPACE_WORDS];
+ u32 *mess = &xvp->cookie_bakery[COOKIE_DIGEST_WORDS];
+ u32 *tail = &mess[COOKIE_MESSAGE_WORDS-1];
+
+ /* Secret recipe depends on the Timestamp, (future)
+ * Sequence and Acknowledgment Numbers, Initiator
+ * Cookie, and others handled by IP variant caller.
+ */
+ *tail-- ^= opts.tsval;
+ *tail-- ^= tcp_rsk(req)->rcv_isn + 1;
+ *tail-- ^= TCP_SKB_CB(skb)->seq + 1;
+
+ /* recommended */
+ *tail-- ^= ((th->dest << 16) | th->source);
+ *tail-- ^= (u32)cvp; /* per sockopt */
+
+ sha_transform((__u32 *)&xvp->cookie_bakery[0],
+ (char *)mess,
+ &workspace[0]);
+ opts.hash_location =
+ (__u8 *)&xvp->cookie_bakery[0];
+ }
+ }
+
th->seq = htonl(TCP_SKB_CB(skb)->seq);
th->ack_seq = htonl(tcp_rsk(req)->rcv_isn + 1);
struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb)
{
+ struct tcp_options_received tcp_opt;
+ u8 *hash_location;
struct inet_request_sock *ireq;
struct inet6_request_sock *ireq6;
struct tcp_request_sock *treq;
int mss;
struct dst_entry *dst;
__u8 rcv_wscale;
- struct tcp_options_received tcp_opt;
if (!sysctl_tcp_syncookies || !th->ack)
goto out;
/* check for timestamp cookie support */
memset(&tcp_opt, 0, sizeof(tcp_opt));
- tcp_parse_options(skb, &tcp_opt, 0, dst);
+ tcp_parse_options(skb, &tcp_opt, &hash_location, 0, dst);
if (tcp_opt.saw_tstamp)
cookie_check_timestamp(&tcp_opt);
*/
static int tcp_v6_conn_request(struct sock *sk, struct sk_buff *skb)
{
+ struct tcp_extend_values tmp_ext;
struct tcp_options_received tmp_opt;
+ u8 *hash_location;
struct request_sock *req;
struct inet6_request_sock *treq;
struct ipv6_pinfo *np = inet6_sk(sk);
tcp_clear_options(&tmp_opt);
tmp_opt.mss_clamp = IPV6_MIN_MTU - sizeof(struct tcphdr) - sizeof(struct ipv6hdr);
tmp_opt.user_mss = tp->rx_opt.user_mss;
+ tcp_parse_options(skb, &tmp_opt, &hash_location, 0, dst);
+
+ if (tmp_opt.cookie_plus > 0 &&
+ tmp_opt.saw_tstamp &&
+ !tp->rx_opt.cookie_out_never &&
+ (sysctl_tcp_cookie_size > 0 ||
+ (tp->cookie_values != NULL &&
+ tp->cookie_values->cookie_desired > 0))) {
+ u8 *c;
+ u32 *d;
+ u32 *mess = &tmp_ext.cookie_bakery[COOKIE_DIGEST_WORDS];
+ int l = tmp_opt.cookie_plus - TCPOLEN_COOKIE_BASE;
+
+ if (tcp_cookie_generator(&tmp_ext.cookie_bakery[0]) != 0)
+ goto drop_and_free;
+
+ /* Secret recipe starts with IP addresses */
+ d = &ipv6_hdr(skb)->daddr.s6_addr32[0];
+ *mess++ ^= *d++;
+ *mess++ ^= *d++;
+ *mess++ ^= *d++;
+ *mess++ ^= *d++;
+ d = &ipv6_hdr(skb)->saddr.s6_addr32[0];
+ *mess++ ^= *d++;
+ *mess++ ^= *d++;
+ *mess++ ^= *d++;
+ *mess++ ^= *d++;
+
+ /* plus variable length Initiator Cookie */
+ c = (u8 *)mess;
+ while (l-- > 0)
+ *c++ ^= *hash_location++;
- tcp_parse_options(skb, &tmp_opt, 0, dst);
+#ifdef CONFIG_SYN_COOKIES
+ want_cookie = 0; /* not our kind of cookie */
+#endif
+ tmp_ext.cookie_out_never = 0; /* false */
+ tmp_ext.cookie_plus = tmp_opt.cookie_plus;
+ } else if (!tp->rx_opt.cookie_in_always) {
+ /* redundant indications, but ensure initialization. */
+ tmp_ext.cookie_out_never = 1; /* true */
+ tmp_ext.cookie_plus = 0;
+ } else {
+ goto drop_and_free;
+ }
+ tmp_ext.cookie_in_always = tp->rx_opt.cookie_in_always;
if (want_cookie && !tmp_opt.saw_tstamp)
tcp_clear_options(&tmp_opt);
security_inet_conn_request(sk, skb, req);
- if (tcp_v6_send_synack(sk, req, NULL) || want_cookie)
+ if (tcp_v6_send_synack(sk, req,
+ (struct request_values *)&tmp_ext) ||
+ want_cookie)
goto drop_and_free;
inet6_csk_reqsk_queue_hash_add(sk, req, TCP_TIMEOUT_INIT);
git://ftp.safe.ca / safe / jmp / linux-2.6 / commitdiff