Firewall: T4651: Add options to match packet size on firewall rules.

4 files changed, 116 insertions, 1 deletions

diff --git a/interface-definitions/firewall.xml.in b/interface-definitions/firewall.xml.in
index 2e9452dfd..f838f1b88 100644
--- a/interface-definitions/firewall.xml.in
+++ b/interface-definitions/firewall.xml.in
@@ -383,6 +383,26 @@
                 </children>
               </node>
               #include <include/firewall/common-rule.xml.i>
+              <leafNode name="ip-length">
+                <properties>
+                  <help>Payload size in bytes, including any extension header</help>
+                  <valueHelp>
+                    <format>u32:1-65535</format>
+                    <description>Numbered packet length</description>
+                  </valueHelp>
+                  <valueHelp>
+                    <format>&lt;start-end&gt;</format>
+                    <description>Packet length range (e.g. 1001-1005)</description>
+                  </valueHelp>
+                  <valueHelp>
+                    <format> </format>
+                    <description>\n\n  Multiple values can be specified as a comma-separated list.\n  For example: '64, 512,1001-1005'</description>
+                  </valueHelp>
+                  <constraint>
+                    <validator name="ip-length"/>
+                  </constraint>
+                </properties>
+              </leafNode>
               <node name="hop-limit">
                 <properties>
                   <help>Hop Limit</help>
@@ -571,6 +591,26 @@
                 </children>
               </node>
               #include <include/firewall/common-rule.xml.i>
+              <leafNode name="ip-length">
+                <properties>
+                  <help>Packet size in bytes, including header and data</help>
+                  <valueHelp>
+                    <format>u32:1-65535</format>
+                    <description>Numbered packet length</description>
+                  </valueHelp>
+                  <valueHelp>
+                    <format>&lt;start-end&gt;</format>
+                    <description>Packet length range (e.g. 1001-1005)</description>
+                  </valueHelp>
+                  <valueHelp>
+                    <format> </format>
+                    <description>\n\n  Multiple values can be specified as a comma-separated list.\n  For example: '64, 512,1001-1005'</description>
+                  </valueHelp>
+                  <constraint>
+                    <validator name="ip-length"/>
+                  </constraint>
+                </properties>
+              </leafNode>
               <node name="icmp">
                 <properties>
                   <help>ICMP type and code information</help>
diff --git a/python/vyos/firewall.py b/python/vyos/firewall.py
index 663c4394a..a4fd64830 100644
--- a/python/vyos/firewall.py
+++ b/python/vyos/firewall.py
@@ -265,6 +265,32 @@ def parse_rule(rule_conf, fw_name, rule_id, ip_name):
                 if 'type' in rule_conf[icmp]:
                     output.append(icmp + ' type ' + rule_conf[icmp]['type'])
 
+
+    if 'ip_length' in rule_conf:
+        #proto = rule_conf['protocol']
+        length = rule_conf['ip_length'].split(',')
+
+        lengths = []
+        negated_lengths = []
+
+        for p in length:
+            if p[0] == '!':
+                negated_lengths.append(p[1:])
+            else:
+                lengths.append(p)
+
+                #if proto == 'tcp_udp':
+                #    proto = 'th'
+
+        if lengths:
+            lengths_str = ','.join(lengths)
+            output.append(f'ip{def_suffix} length {{{lengths_str}}}')
+
+        if negated_lengths:
+            negated_lengths_str = ','.join(negated_lengths)
+            output.append(f'ip{def_suffix} length != {{{negated_lengths_str}}}')
+
+
     if 'ipsec' in rule_conf:
         if 'match_ipsec' in rule_conf['ipsec']:
             output.append('meta ipsec == 1')
diff --git a/smoketest/scripts/cli/test_firewall.py b/smoketest/scripts/cli/test_firewall.py
index 684a07681..5ca00eafa 100755
--- a/smoketest/scripts/cli/test_firewall.py
+++ b/smoketest/scripts/cli/test_firewall.py
@@ -209,6 +209,13 @@ class TestFirewall(VyOSUnitTestSHIM.TestCase):
         self.cli_set(['firewall', 'name', 'smoketest', 'rule', '5', 'tcp', 'flags', 'syn'])
         self.cli_set(['firewall', 'name', 'smoketest', 'rule', '5', 'tcp', 'mss', mss_range])
 
+        self.cli_set(['firewall', 'name', 'smoketest', 'rule', '6', 'action', 'accept'])
+        self.cli_set(['firewall', 'name', 'smoketest', 'rule', '6', 'ip-length', '64,512,1024'])
+        self.cli_set(['firewall', 'name', 'smoketest', 'rule', '7', 'action', 'accept'])
+        self.cli_set(['firewall', 'name', 'smoketest', 'rule', '7', 'ip-length', '0-30000'])
+        self.cli_set(['firewall', 'name', 'smoketest', 'rule', '8', 'action', 'accept'])
+        self.cli_set(['firewall', 'name', 'smoketest', 'rule', '8', 'ip-length', '!60000-65535'])
+
         self.cli_set(['interfaces', 'ethernet', 'eth0', 'firewall', 'in', 'name', 'smoketest'])
 
         self.cli_commit()
@@ -220,7 +227,10 @@ class TestFirewall(VyOSUnitTestSHIM.TestCase):
             ['tcp dport { 22 }', 'limit rate 5/minute', 'return'],
             ['log prefix "[smoketest-default-D]"','smoketest default-action', 'drop'],
             ['tcp dport { 22 }', 'add @RECENT_smoketest_4 { ip saddr limit rate over 10/minute burst 10 packets }', 'drop'],
-            [f'tcp flags & syn == syn tcp option maxseg size {mss_range}']
+            [f'tcp flags & syn == syn tcp option maxseg size {mss_range}'],
+            ['ip length { 64, 512, 1024 }', 'return'],
+            ['ip length { 0-30000 }', 'return'],
+            ['ip length != { 60000-65535 }', 'return']
         ]
 
         self.verify_nftables(nftables_search, 'ip filter')
@@ -239,6 +249,13 @@ class TestFirewall(VyOSUnitTestSHIM.TestCase):
         self.cli_set(['firewall', 'ipv6-name', 'v6-smoketest', 'rule', '2', 'protocol', 'tcp_udp'])
         self.cli_set(['firewall', 'ipv6-name', 'v6-smoketest', 'rule', '2', 'destination', 'port', '8888'])
 
+        self.cli_set(['firewall', 'ipv6-name', 'v6-smoketest', 'rule', '3', 'action', 'accept'])
+        self.cli_set(['firewall', 'ipv6-name', 'v6-smoketest', 'rule', '3', 'ip-length', '64,512,1024'])
+        self.cli_set(['firewall', 'ipv6-name', 'v6-smoketest', 'rule', '4', 'action', 'accept'])
+        self.cli_set(['firewall', 'ipv6-name', 'v6-smoketest', 'rule', '4', 'ip-length', '0-30000'])
+        self.cli_set(['firewall', 'ipv6-name', 'v6-smoketest', 'rule', '5', 'action', 'accept'])
+        self.cli_set(['firewall', 'ipv6-name', 'v6-smoketest', 'rule', '5', 'ip-length', '!60000-65535'])
+
         self.cli_set(['interfaces', 'ethernet', 'eth0', 'firewall', 'in', 'ipv6-name', 'v6-smoketest'])
 
         self.cli_commit()
@@ -247,6 +264,9 @@ class TestFirewall(VyOSUnitTestSHIM.TestCase):
             ['iifname "eth0"', 'jump NAME6_v6-smoketest'],
             ['saddr 2002::1', 'daddr 2002::1:1', 'log prefix "[v6-smoketest-1-A]" level crit', 'return'],
             ['meta l4proto { tcp, udp }', 'th dport { 8888 }', 'reject'],
+            ['ip6 length { 64, 512, 1024 }', 'return'],
+            ['ip6 length { 0-30000 }', 'return'],
+            ['ip6 length != { 60000-65535 }', 'return'],
             ['smoketest default-action', 'log prefix "[v6-smoketest-default-D]"', 'drop']
         ]
 
diff --git a/src/validators/ip-length b/src/validators/ip-length
new file mode 100755
index 000000000..d96093849
--- /dev/null
+++ b/src/validators/ip-length
@@ -0,0 +1,29 @@
+#!/usr/bin/python3
+
+from sys import argv
+from sys import exit
+import re
+
+if __name__ == '__main__':
+    if len(argv)>1:
+        lengths = argv[1].split(",")
+
+        for length in lengths:
+            if length and length[0] == '!':
+                length = length[1:]
+            if re.match('^[0-9]{1,5}-[0-9]{1,5}$', length):
+                length_1, length_2 = length.split('-')
+                if int(length_1) not in range(0, 65536) or int(length_2) not in range(0, 65536):
+                    print(f'Error: {length} is not a valid length range')
+                    exit(1)
+                if int(length_1) > int(length_2):
+                    print(f'Error: {length} is not a valid length range')
+                    exit(1)
+            elif length.isnumeric():
+                if int(length) not in range(0, 65536):
+                    print(f'Error: {length} is not a valid length value')
+                    exit(1)
+    else:
+        exit(2)
+
+    exit(0)
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