5 files changed, 57 insertions, 23 deletions

diff --git a/include/linux/tcp.h b/include/linux/tcp.h
index f869ae8afbaf..a48d00318683 100644
--- a/include/linux/tcp.h
+++ b/include/linux/tcp.h
@@ -58,6 +58,7 @@ static inline unsigned int tcp_optlen(const struct sk_buff *skb)
 struct tcp_fastopen_cookie {
         s8      len;
         u8      val[TCP_FASTOPEN_COOKIE_MAX];
+        bool    exp;    /* In RFC6994 experimental option format */
 };
 
 /* This defines a selective acknowledgement block. */
diff --git a/include/net/tcp.h b/include/net/tcp.h
index 963303fb96ae..7292c3c575bc 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -179,6 +179,7 @@ void tcp_time_wait(struct sock *sk, int state, int timeo);
 #define TCPOPT_SACK             5       /* SACK Block */
 #define TCPOPT_TIMESTAMP        8       /* Better RTT estimations/PAWS */
 #define TCPOPT_MD5SIG           19      /* MD5 Signature (RFC2385) */
+#define TCPOPT_FASTOPEN         34      /* Fast open (RFC7413) */
 #define TCPOPT_EXP              254     /* Experimental */
 /* Magic number to be after the option value for sharing TCP
  * experimental options. See draft-ietf-tcpm-experimental-options-00.txt
@@ -194,6 +195,7 @@ void tcp_time_wait(struct sock *sk, int state, int timeo);
 #define TCPOLEN_SACK_PERM      2
 #define TCPOLEN_TIMESTAMP      10
 #define TCPOLEN_MD5SIG         18
+#define TCPOLEN_FASTOPEN_BASE  2
 #define TCPOLEN_EXP_FASTOPEN_BASE  4
 
 /* But this is what stacks really send out. */
diff --git a/net/ipv4/tcp_fastopen.c b/net/ipv4/tcp_fastopen.c
index 5da55e2b5cd2..e3d87aca6be8 100644
--- a/net/ipv4/tcp_fastopen.c
+++ b/net/ipv4/tcp_fastopen.c
@@ -303,6 +303,7 @@ fastopen:
         } else if (foc->len > 0) /* Client presents an invalid cookie */
                 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPFASTOPENPASSIVEFAIL);
 
+        valid_foc.exp = foc->exp;
         *foc = valid_foc;
         return false;
 }
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index c1ce304ba8d2..24f1630b2afb 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -3603,6 +3603,23 @@ old_ack:
         return 0;
 }
 
+static void tcp_parse_fastopen_option(int len, const unsigned char *cookie,
+                                      bool syn, struct tcp_fastopen_cookie *foc,
+                                      bool exp_opt)
+{
+        /* Valid only in SYN or SYN-ACK with an even length.  */
+        if (!foc || !syn || len < 0 || (len & 1))
+                return;
+
+        if (len >= TCP_FASTOPEN_COOKIE_MIN &&
+            len <= TCP_FASTOPEN_COOKIE_MAX)
+                memcpy(foc->val, cookie, len);
+        else if (len != 0)
+                len = -1;
+        foc->len = len;
+        foc->exp = exp_opt;
+}
+
 /* 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.
@@ -3692,21 +3709,22 @@ void tcp_parse_options(const struct sk_buff *skb,
                                  */
                                 break;
 #endif
+                        case TCPOPT_FASTOPEN:
+                                tcp_parse_fastopen_option(
+                                        opsize - TCPOLEN_FASTOPEN_BASE,
+                                        ptr, th->syn, foc, false);
+                                break;
+
                         case TCPOPT_EXP:
                                 /* Fast Open option shares code 254 using a
-                                 * 16 bits magic number. It's valid only in
-                                 * SYN or SYN-ACK with an even size.
+                                 * 16 bits magic number.
                                  */
-                                if (opsize < TCPOLEN_EXP_FASTOPEN_BASE ||
-                                    get_unaligned_be16(ptr) != TCPOPT_FASTOPEN_MAGIC ||
-                                    !foc || !th->syn || (opsize & 1))
-                                        break;
-                                foc->len = opsize - TCPOLEN_EXP_FASTOPEN_BASE;
-                                if (foc->len >= TCP_FASTOPEN_COOKIE_MIN &&
-                                    foc->len <= TCP_FASTOPEN_COOKIE_MAX)
-                                        memcpy(foc->val, ptr + 2, foc->len);
-                                else if (foc->len != 0)
-                                        foc->len = -1;
+                                if (opsize >= TCPOLEN_EXP_FASTOPEN_BASE &&
+                                    get_unaligned_be16(ptr) ==
+                                    TCPOPT_FASTOPEN_MAGIC)
+                                        tcp_parse_fastopen_option(opsize -
+                                                TCPOLEN_EXP_FASTOPEN_BASE,
+                                                ptr + 2, th->syn, foc, true);
                                 break;
 
                         }
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 7404e5238e00..464bd8c5de69 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -518,17 +518,26 @@ static void tcp_options_write(__be32 *ptr, struct tcp_sock *tp,
 
         if (unlikely(OPTION_FAST_OPEN_COOKIE & options)) {
                 struct tcp_fastopen_cookie *foc = opts->fastopen_cookie;
+                u8 *p = (u8 *)ptr;
+                u32 len; /* Fast Open option length */
+
+                if (foc->exp) {
+                        len = TCPOLEN_EXP_FASTOPEN_BASE + foc->len;
+                        *ptr = htonl((TCPOPT_EXP << 24) | (len << 16) |
+                                     TCPOPT_FASTOPEN_MAGIC);
+                        p += TCPOLEN_EXP_FASTOPEN_BASE;
+                } else {
+                        len = TCPOLEN_FASTOPEN_BASE + foc->len;
+                        *p++ = TCPOPT_FASTOPEN;
+                        *p++ = len;
+                }
 
-                *ptr++ = htonl((TCPOPT_EXP << 24) |
-                               ((TCPOLEN_EXP_FASTOPEN_BASE + foc->len) << 16) |
-                               TCPOPT_FASTOPEN_MAGIC);
-
-                memcpy(ptr, foc->val, foc->len);
-                if ((foc->len & 3) == 2) {
-                        u8 *align = ((u8 *)ptr) + foc->len;
-                        align[0] = align[1] = TCPOPT_NOP;
+                memcpy(p, foc->val, foc->len);
+                if ((len & 3) == 2) {
+                        p[foc->len] = TCPOPT_NOP;
+                        p[foc->len + 1] = TCPOPT_NOP;
                 }
-                ptr += (foc->len + 3) >> 2;
+                ptr += (len + 3) >> 2;
         }
 }
 
@@ -641,8 +650,11 @@ static unsigned int tcp_synack_options(struct sock *sk,
                 if (unlikely(!ireq->tstamp_ok))
                         remaining -= TCPOLEN_SACKPERM_ALIGNED;
         }
-        if (foc && foc->len >= 0) {
-                u32 need = TCPOLEN_EXP_FASTOPEN_BASE + foc->len;
+        if (foc != NULL && foc->len >= 0) {
+                u32 need = foc->len;
+
+                need += foc->exp ? TCPOLEN_EXP_FASTOPEN_BASE :
+                                   TCPOLEN_FASTOPEN_BASE;
                 need = (need + 3) & ~3U;  /* Align to 32 bits */
                 if (remaining >= need) {
                         opts->options |= OPTION_FAST_OPEN_COOKIE;