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107 lines
3.9 KiB
107 lines
3.9 KiB
Re-introduce bad_port_check(), which upstream dropped between 2.3.13 and 2.3.14
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for it having been "rather antiquated for years", with no justification given
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for that claim.
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--- xinetd-2.3.15/xinetd/builtins.c 2012-05-09 17:40:29.000000000 +0200
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+++ xinetd-2.3.15.new/xinetd/builtins.c 2012-05-14 10:25:00.431529805 +0200
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@@ -52,6 +52,7 @@ static void dgram_daytime(const struct s
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static void stream_chargen(const struct server *) ;
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static void dgram_chargen(const struct server *) ;
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static void tcpmux_handler(const struct server *) ;
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+static int bad_port_check(const union xsockaddr *, const char *);
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/*
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* SG - This is the call sequence to get to a built-in service
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@@ -163,6 +164,25 @@ static void stream_echo( const struct se
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Sclose(descriptor);
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}
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+/* For internal UDP services, make sure we don't respond to our ports
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+ * on other servers and to low ports of other services (such as DNS).
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+ * This can cause looping.
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+ */
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+static int bad_port_check( const union xsockaddr *sa, const char *func )
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+{
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+ uint16_t port = 0;
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+
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+ port = ntohs( xaddrport( sa ) );
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+
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+ if ( port < 1024 ) {
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+ msg(LOG_WARNING, func,
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+ "Possible Denial of Service attack from %s %d", xaddrname(sa), port);
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+ return (-1);
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+ }
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+
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+ return (0);
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+}
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+
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static void dgram_echo( const struct server *serp )
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{
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char buf[ DATAGRAM_SIZE ] ;
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@@ -170,6 +190,7 @@ static void dgram_echo( const struct ser
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ssize_t cc ;
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socklen_t sin_len = 0;
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int descriptor = SERVER_FD( serp ) ;
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+ const char *func = "dgram_echo" ;
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if( SC_IPV4( SVC_CONF( SERVER_SERVICE( serp ) ) ) )
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sin_len = sizeof( struct sockaddr_in );
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@@ -178,6 +199,7 @@ static void dgram_echo( const struct ser
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cc = recvfrom( descriptor, buf, sizeof( buf ), 0, (struct sockaddr *)( &lsin ), &sin_len ) ;
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if ( cc != (ssize_t)-1 ) {
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+ if( bad_port_check(&lsin, func) != 0 ) return;
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(void) sendto( descriptor, buf, (size_t)cc, 0, SA( &lsin ), sizeof( lsin ) ) ;
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}
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}
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@@ -292,6 +314,7 @@ static void dgram_daytime( const struct
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unsigned int buflen = sizeof( time_buf ) ;
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int descriptor = SERVER_FD( serp ) ;
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ssize_t val;
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+ const char *func = "dgram_daytime" ;
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if ( SC_IPV4( SVC_CONF( SERVER_SERVICE( serp ) ) ) )
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sin_len = sizeof( struct sockaddr_in );
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@@ -303,6 +326,8 @@ static void dgram_daytime( const struct
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if ( val == (ssize_t)-1 )
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return ;
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+ if( bad_port_check(&lsin, func) != 0 ) return;
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+
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daytime_protocol( time_buf, &buflen ) ;
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(void) sendto( descriptor, time_buf, buflen, 0, SA(&lsin), sizeof( lsin ) ) ;
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@@ -359,6 +384,7 @@ static void dgram_time( const struct ser
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socklen_t sin_len = 0 ;
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int fd = SERVER_FD( serp ) ;
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ssize_t val;
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+ const char *func = "dgram_time" ;
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if ( SC_IPV4( SVC_CONF( SERVER_SERVICE( serp ) ) ) )
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sin_len = sizeof( struct sockaddr_in );
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@@ -368,6 +394,7 @@ static void dgram_time( const struct ser
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val = recvfrom( fd, buf, sizeof( buf ), 0, (struct sockaddr *)( &lsin ), &sin_len );
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if ( val == (ssize_t)-1 )
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return ;
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+ if( bad_port_check(&lsin, func) != 0 ) return;
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time_protocol( time_buf ) ;
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(void) sendto( fd, (char *) time_buf, 4, 0, SA( &lsin ), sin_len ) ;
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@@ -466,6 +493,7 @@ static void dgram_chargen( const struct
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int fd = SERVER_FD( serp ) ;
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unsigned int left = sizeof( buf ) ;
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ssize_t val;
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+ const char *func = "dgram_chargen" ;
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if ( SC_IPV4( SVC_CONF( SERVER_SERVICE( serp ) ) ) )
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sin_len = sizeof( struct sockaddr_in );
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@@ -480,6 +508,8 @@ static void dgram_chargen( const struct
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bad_variable = 1 ; /* this will cause a compilation error */
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#endif
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+ if( bad_port_check(&lsin, func) != 0 ) return;
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+
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for ( p = buf ; left > 2 ; left -= len, p += len )
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{
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len = min( LINE_LENGTH+2, left ) ;
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