firewall3: make reject types selectable by user

RFC 6092 recommends in section 3.3.1 that an IPv6 CPE must respond to
unsolicited inbound SYNs with an ICMPv6 Destination Unreachable error
code 1 (Communication with destination administratively prohibited).

Signed-off-by: Alin Nastac <alin.nastac@gmail.com>
Acked-by: Jo-Philipp Wich <jo@mein.io>

diff --git a/defaults.c b/defaults.c
index 11fbf0dd8f74a51e4b2d95fd0bb7e742d65cd8f4..f42eed615b5926b32c62d7f2833b112442add39b 100644 (file)
--- a/defaults.c
+++ b/defaults.c
@@ -41,6 +41,8 @@ const struct fw3_option fw3_flag_opts[] = {
        FW3_OPT("output",              target,   defaults, policy_output),
 
        FW3_OPT("drop_invalid",        bool,     defaults, drop_invalid),
+       FW3_OPT("tcp_reject_code",     reject_code, defaults, tcp_reject_code),
+       FW3_OPT("any_reject_code",     reject_code, defaults, any_reject_code),
 
        FW3_OPT("syn_flood",           bool,     defaults, syn_flood),
        FW3_OPT("synflood_protect",    bool,     defaults, syn_flood),
@@ -102,6 +104,30 @@ check_offloading(struct uci_element *e, bool *offloading)
        *offloading = false;
 }
 
+static void
+check_any_reject_code(struct uci_element *e, enum fw3_reject_code *any_reject_code)
+{
+       if (*any_reject_code == FW3_REJECT_CODE_TCP_RESET) {
+               warn_elem(e, "tcp-reset not valid for any_reject_code, defaulting to port-unreach");
+               *any_reject_code = FW3_REJECT_CODE_PORT_UNREACH;
+       }
+}
+
+static const char*
+get_reject_code(enum fw3_family family, enum fw3_reject_code reject_code)
+{
+       switch (reject_code) {
+       case FW3_REJECT_CODE_TCP_RESET:
+               return "tcp-reset";
+       case FW3_REJECT_CODE_PORT_UNREACH:
+               return "port-unreach";
+       case FW3_REJECT_CODE_ADM_PROHIBITED:
+               return family == FW3_FAMILY_V6 ? "adm-prohibited": "admin-prohib";
+       default:
+               return "unknown";
+       }
+}
+
 void
 fw3_load_defaults(struct fw3_state *state, struct uci_package *p)
 {
@@ -111,6 +137,8 @@ fw3_load_defaults(struct fw3_state *state, struct uci_package *p)
 
        bool seen = false;
 
+       defs->tcp_reject_code      = FW3_REJECT_CODE_TCP_RESET;
+       defs->any_reject_code      = FW3_REJECT_CODE_PORT_UNREACH;
        defs->syn_flood_rate.rate  = 25;
        defs->syn_flood_rate.burst = 50;
        defs->tcp_syncookies       = true;
@@ -138,6 +166,8 @@ fw3_load_defaults(struct fw3_state *state, struct uci_package *p)
                check_policy(e, &defs->policy_output, "output");
                check_policy(e, &defs->policy_forward, "forward");
 
+               check_any_reject_code(e, &defs->any_reject_code);
+
                check_offloading(e, &defs->flow_offloading);
        }
 }
@@ -278,12 +308,12 @@ fw3_print_default_head_rules(struct fw3_ipt_handle *handle,
 
                r = fw3_ipt_rule_create(handle, &tcp, NULL, NULL, NULL, NULL);
                fw3_ipt_rule_target(r, "REJECT");
-               fw3_ipt_rule_addarg(r, false, "--reject-with", "tcp-reset");
+               fw3_ipt_rule_addarg(r, false, "--reject-with", get_reject_code(handle->family, defs->tcp_reject_code));
                fw3_ipt_rule_append(r, "reject");
 
                r = fw3_ipt_rule_new(handle);
                fw3_ipt_rule_target(r, "REJECT");
-               fw3_ipt_rule_addarg(r, false, "--reject-with", "port-unreach");
+               fw3_ipt_rule_addarg(r, false, "--reject-with", get_reject_code(handle->family, defs->any_reject_code));
                fw3_ipt_rule_append(r, "reject");
 
                break;

diff --git a/options.c b/options.c
index 087aa630469afa8eea81238a4fb9c6accc44d414..c85bafd4d9123a66ba9c7dc46e4bf339f5d753c5 100644 (file)
--- a/options.c
+++ b/options.c
@@ -86,6 +86,12 @@ const char *fw3_flag_names[__FW3_FLAG_MAX] = {
        "DROP",
 };
 
+const char *fw3_reject_code_names[__FW3_REJECT_CODE_MAX] = {
+       "tcp-reset",
+       "port-unreach",
+       "adm-prohibited",
+};
+
 const char *fw3_limit_units[__FW3_LIMIT_UNIT_MAX] = {
        "second",
        "minute",
@@ -169,6 +175,13 @@ fw3_parse_target(void *ptr, const char *val, bool is_list)
                          FW3_FLAG_ACCEPT, FW3_FLAG_MASQUERADE);
 }
 
+bool
+fw3_parse_reject_code(void *ptr, const char *val, bool is_list)
+{
+       return parse_enum(ptr, val, &fw3_reject_code_names[FW3_REJECT_CODE_TCP_RESET],
+                         FW3_REJECT_CODE_TCP_RESET, FW3_REJECT_CODE_ADM_PROHIBITED);
+}
+
 bool
 fw3_parse_limit(void *ptr, const char *val, bool is_list)
 {

diff --git a/options.h b/options.h
index 08fecf61e33df60740b3f783bc1c5d917e19684e..0b73a8433e9c0480b87a715d2ecb3bd52576a63f 100644 (file)
--- a/options.h
+++ b/options.h
@@ -88,6 +88,15 @@ enum fw3_flag
        __FW3_FLAG_MAX
 };
 
+enum fw3_reject_code
+{
+       FW3_REJECT_CODE_TCP_RESET      = 0,
+       FW3_REJECT_CODE_PORT_UNREACH   = 1,
+       FW3_REJECT_CODE_ADM_PROHIBITED = 2,
+
+       __FW3_REJECT_CODE_MAX
+};
+
 extern const char *fw3_flag_names[__FW3_FLAG_MAX];
 
 
@@ -276,6 +285,8 @@ struct fw3_defaults
        enum fw3_flag policy_forward;
 
        bool drop_invalid;
+       enum fw3_reject_code tcp_reject_code;
+       enum fw3_reject_code any_reject_code;
 
        bool syn_flood;
        struct fw3_limit syn_flood_rate;
@@ -580,6 +591,7 @@ bool fw3_parse_bool(void *ptr, const char *val, bool is_list);
 bool fw3_parse_int(void *ptr, const char *val, bool is_list);
 bool fw3_parse_string(void *ptr, const char *val, bool is_list);
 bool fw3_parse_target(void *ptr, const char *val, bool is_list);
+bool fw3_parse_reject_code(void *ptr, const char *val, bool is_list);
 bool fw3_parse_limit(void *ptr, const char *val, bool is_list);
 bool fw3_parse_device(void *ptr, const char *val, bool is_list);
 bool fw3_parse_address(void *ptr, const char *val, bool is_list);