From 771908d313ee9c255adfb5e4fdba4d6797c18409 Mon Sep 17 00:00:00 2001

From: Amos Jeffries <yadij@users.noreply.github.com>

Date: Thu, 7 Mar 2019 13:50:38 +0000

Subject: [PATCH] Bug 4928: Cannot convert non-IPv4 to IPv4 (#379)

... when reaching client_ip_max_connections

The client_ip_max_connections limit is checked before the TCP dst-IP is located for the newly received TCP connection. This leaves Squid unable to fetch the NFMARK or similar

details later on (they do not exist for [::]).

Move client_ip_max_connections test later in the TCP accept process to ensure dst-IP is known when the error is produced.

---

 src/comm/TcpAcceptor.cc | 82 ++++++++++++++++++++---------------------

 1 file changed, 39 insertions(+), 43 deletions(-)

diff --git a/src/comm/TcpAcceptor.cc b/src/comm/TcpAcceptor.cc

index d4b576d..936aa30 100644

--- a/src/comm/TcpAcceptor.cc

+++ b/src/comm/TcpAcceptor.cc

@@ -282,7 +282,16 @@ Comm::TcpAcceptor::acceptOne()

     ConnectionPointer newConnDetails = new Connection();

     const Comm::Flag flag = oldAccept(newConnDetails);

-    if (flag == Comm::COMM_ERROR) {

+    /* Check for errors */

+    if (!newConnDetails->isOpen()) {

+

+        if (flag == Comm::NOMESSAGE) {

+            /* register interest again */

+            debugs(5, 5, HERE << "try later: " << conn << " handler Subscription: " << theCallSub);

+            SetSelect(conn->fd, COMM_SELECT_READ, doAccept, this, 0);

+            return;

+        }

+

         // A non-recoverable error; notify the caller */

         debugs(5, 5, HERE << "non-recoverable error:" << status() << " handler Subscription: " << theCallSub);

         if (intendedForUserConnections())

@@ -292,16 +301,12 @@ Comm::TcpAcceptor::acceptOne()

         return;

     }

-    if (flag == Comm::NOMESSAGE) {

-        /* register interest again */

-        debugs(5, 5, "try later: " << conn << " handler Subscription: " << theCallSub);

-    } else {

-        debugs(5, 5, "Listener: " << conn <<

-               " accepted new connection " << newConnDetails <<

-               " handler Subscription: " << theCallSub);

-        notify(flag, newConnDetails);

-    }

+    newConnDetails->nfmark = Ip::Qos::getNfmarkFromConnection(newConnDetails, Ip::Qos::dirAccepted);

+    debugs(5, 5, HERE << "Listener: " << conn <<

+           " accepted new connection " << newConnDetails <<

+           " handler Subscription: " << theCallSub);

+    notify(flag, newConnDetails);

     SetSelect(conn->fd, COMM_SELECT_READ, doAccept, this, 0);

 }

@@ -341,8 +346,8 @@ Comm::TcpAcceptor::notify(const Comm::Flag flag, const Comm::ConnectionPointer &

  *

  * \retval Comm::OK          success. details parameter filled.

  * \retval Comm::NOMESSAGE   attempted accept() but nothing useful came in.

- *                           Or this client has too many connections already.

  * \retval Comm::COMM_ERROR  an outright failure occurred.

+ *                           Or this client has too many connections already.

  */

 Comm::Flag

 Comm::TcpAcceptor::oldAccept(Comm::ConnectionPointer &details)

@@ -383,6 +388,15 @@ Comm::TcpAcceptor::oldAccept(Comm::ConnectionPointer &details)

     details->remote = *gai;

+    if ( Config.client_ip_max_connections >= 0) {

+        if (clientdbEstablished(details->remote, 0) > Config.client_ip_max_connections) {

+            debugs(50, DBG_IMPORTANT, "WARNING: " << details->remote << " attempting more than " << Config.client_ip_max_connections << " connections.");

+            Ip::Address::FreeAddr(gai);

+            PROF_stop(comm_accept);

+            return Comm::COMM_ERROR;

+        }

+    }

+

     // lookup the local-end details of this new connection

     Ip::Address::InitAddr(gai);

     details->local.setEmpty();

@@ -396,6 +410,23 @@ Comm::TcpAcceptor::oldAccept(Comm::ConnectionPointer &details)

     details->local = *gai;

     Ip::Address::FreeAddr(gai);

+    /* fdstat update */

+    fdd_table[sock].close_file = NULL;

+    fdd_table[sock].close_line = 0;

+

+    fde *F = &fd_table[sock];

+    details->remote.toStr(F->ipaddr,MAX_IPSTRLEN);

+    F->remote_port = details->remote.port();

+    F->local_addr = details->local;

+    F->sock_family = details->local.isIPv6()?AF_INET6:AF_INET;

+

+    // set socket flags

+    commSetCloseOnExec(sock);

+    commSetNonBlocking(sock);

+

+    /* IFF the socket is (tproxy) transparent, pass the flag down to allow spoofing */

+    F->flags.transparent = fd_table[conn->fd].flags.transparent; // XXX: can we remove this line yet?

+

     // Perform NAT or TPROXY operations to retrieve the real client/dest IP addresses

     if (conn->flags&(COMM_TRANSPARENT|COMM_INTERCEPTION) && !Ip::Interceptor.Lookup(details, conn)) {

         debugs(50, DBG_IMPORTANT, "ERROR: NAT/TPROXY lookup failed to locate original IPs on " << details);

@@ -414,33 +445,6 @@ Comm::TcpAcceptor::oldAccept(Comm::ConnectionPointer &details)

     }

 #endif

-    details->nfmark = Ip::Qos::getNfmarkFromConnection(details, Ip::Qos::dirAccepted);

-

-    if (Config.client_ip_max_connections >= 0) {

-        if (clientdbEstablished(details->remote, 0) > Config.client_ip_max_connections) {

-            debugs(50, DBG_IMPORTANT, "WARNING: " << details->remote << " attempting more than " << Config.client_ip_max_connections << " connections.");

-            PROF_stop(comm_accept);

-            return Comm::NOMESSAGE;

-        }

-    }

-

-    /* fdstat update */

-    fdd_table[sock].close_file = NULL;

-    fdd_table[sock].close_line = 0;

-

-    fde *F = &fd_table[sock];

-    details->remote.toStr(F->ipaddr,MAX_IPSTRLEN);

-    F->remote_port = details->remote.port();

-    F->local_addr = details->local;

-    F->sock_family = details->local.isIPv6()?AF_INET6:AF_INET;

-

-    // set socket flags

-    commSetCloseOnExec(sock);

-    commSetNonBlocking(sock);

-

-    /* IFF the socket is (tproxy) transparent, pass the flag down to allow spoofing */

-    F->flags.transparent = fd_table[conn->fd].flags.transparent; // XXX: can we remove this line yet?

-

     PROF_stop(comm_accept);

     return Comm::OK;

 }