firewall: set firewall rules for WireGuard

src/core/devices/nm-device-wireguard.c

@@ -23,6 +23,7 @@
 #include "nm-active-connection.h"
 #include "nm-act-request.h"
 #include "dns/nm-dns-manager.h"
+#include "nm-firewall-utils.h"
 
 #define _NMLOG_DEVICE_TYPE NMDeviceWireGuard
 #include "nm-device-logging.h"
@@ -120,6 +121,14 @@ typedef struct {
     CList       lst_peers_head;
     GHashTable *peers;
 
+    union {
+        struct {
+            NMFirewallConfig *fw_config_6;
+            NMFirewallConfig *fw_config_4;
+        };
+        NMFirewallConfig *fw_config_x[2];
+    };
+
     /* counts the numbers of peers that are currently resolving. */
     guint peers_resolving_cnt;
 
@@ -1423,6 +1432,7 @@ link_config(NMDeviceWireGuard   *self,
 {
     NMDeviceWireGuardPrivate                   *priv = NM_DEVICE_WIREGUARD_GET_PRIVATE(self);
     nm_auto_bzero_secret_ptr NMSecretPtr        wg_lnk_clear_private_key = NM_SECRET_PTR_INIT();
+    const char                                 *ip_iface;
     NMSettingWireGuard                         *s_wg;
     NMConnection                               *connection;
     NMActStageReturn                            ret;
@@ -1436,6 +1446,7 @@ link_config(NMDeviceWireGuard   *self,
     NMPlatformWireGuardChangeFlags              wg_change_flags;
     int                                         ifindex;
     int                                         r;
+    int                                         IS_IPv4;
 
     NM_SET_OUT(out_failure_reason, NM_DEVICE_STATE_REASON_NONE);
 
@@ -1478,8 +1489,9 @@ link_config(NMDeviceWireGuard   *self,
         }
     }
 
-    ifindex = nm_device_get_ip_ifindex(NM_DEVICE(self));
+    ifindex  = nm_device_get_ip_ifindex(NM_DEVICE(self));
-    if (ifindex <= 0) {
+    ip_iface = nm_device_get_ip_iface(NM_DEVICE(self));
+    if (ifindex <= 0 || !ip_iface) {
         NM_SET_OUT(out_failure_reason, NM_DEVICE_STATE_REASON_CONFIG_FAILED);
         return NM_ACT_STAGE_RETURN_FAILURE;
     }
@@ -1537,6 +1549,17 @@ link_config(NMDeviceWireGuard   *self,
         return NM_ACT_STAGE_RETURN_FAILURE;
     }
 
+    for (IS_IPv4 = 1; IS_IPv4 >= 0; IS_IPv4--) {
+        //XXX
+        nm_firewall_config_apply(priv->fw_config_x[IS_IPv4], FALSE);
+        nm_clear_pointer(&priv->fw_config_x[IS_IPv4], nm_firewall_config_free);
+        priv->fw_config_x[IS_IPv4] = nm_firewall_config_new_wireguard(ip_iface,
+                                                                      IS_IPv4 ? AF_INET : AF_INET6,
+                                                                      wg_lnk.fwmark,
+                                                                      NULL,
+                                                                      0);
+    }
+
     return NM_ACT_STAGE_RETURN_SUCCESS;
 }
 

src/core/nm-firewall-utils.c

@@ -17,6 +17,7 @@
 
 typedef enum _nm_packed {
     FIREWALL_TOPIC_IP4_SHARED,
+    FIREWALL_TOPIC_WIREGUARD,
 } FirewallTopic;
 
 /*****************************************************************************/
@@ -689,6 +690,86 @@ _fw_nft_set_ip4_shared(gboolean up, const char *ip_iface, in_addr_t addr, guint8
 
 /*****************************************************************************/
 
+static void
+_fw_nft_set_wireguard(gboolean        up,
+                      const char     *ip_iface,
+                      int             addr_family,
+                      guint32         fwmark,
+                      const NMIPAddr *addrs,
+                      gsize           addrs_len)
+{
+    const int                IS_IPv4 = NM_IS_IPv4(addr_family);
+    nm_auto_str_buf NMStrBuf strbuf  = NM_STR_BUF_INIT(NM_UTILS_GET_NEXT_REALLOC_SIZE_1000, FALSE);
+    gs_unref_bytes GBytes   *stdin_buf  = NULL;
+    gs_free char            *table_name = NULL;
+    gs_free char            *ss1        = NULL;
+    const char              *pf         = IS_IPv4 ? "ip" : "ip6";
+    gsize                    i;
+
+    table_name = _share_iptables_get_name(FALSE, "nm-wg", ip_iface);
+
+    /* Taken from wg-quick:
+     * https://git.zx2c4.com/wireguard-tools/tree/src/wg-quick/linux.bash?id=1fd95708391088742c139010cc6b821add941dec#n228 */
+
+#define _append(p_strbuf, fmt, ...) nm_str_buf_append_printf((p_strbuf), "" fmt "\n", ##__VA_ARGS__)
+
+    _append(&strbuf, "add table %s %s", pf, table_name);
+    _append(&strbuf, "%s table %s %s", up ? "flush" : "delete", pf, table_name);
+
+    if (up) {
+        _append(&strbuf,
+                "add chain %s %s preraw {"
+                " type filter hook prerouting priority -300; "
+                "};",
+                pf,
+                table_name);
+        _append(&strbuf,
+                "add chain %s %s premangle {"
+                " type filter hook prerouting priority -150; "
+                "};",
+                pf,
+                table_name);
+        _append(&strbuf,
+                "add chain %s %s postmangle {"
+                " type filter hook postrouting priority -150; "
+                "};",
+                pf,
+                table_name);
+        for (i = 0; i < addrs_len; i++) {
+            char addr_buf[NM_UTILS_INET_ADDRSTRLEN];
+
+            _append(
+                &strbuf,
+                "add rule %s %s preraw iifname != \"%s\" %s daddr %s fib saddr type != local drop",
+                pf,
+                table_name,
+                ip_iface,
+                pf,
+                nm_utils_inet_ntop(addr_family, &addrs[i], addr_buf));
+        }
+        _append(&strbuf,
+                "add rule %s %s postmangle meta l4proto udp mark %u ct mark set mark",
+                pf,
+                table_name,
+                fwmark);
+        _append(&strbuf,
+                "add rule %s %s premangle meta l4proto udp meta mark set ct mark",
+                pf,
+                table_name);
+    }
+
+    nm_log_trace(LOGD_SHARING,
+                 "firewall: nft command: [ %s ]",
+                 nm_utils_str_utf8safe_escape(nm_str_buf_get_str(&strbuf),
+                                              NM_UTILS_STR_UTF8_SAFE_FLAG_ESCAPE_CTRL,
+                                              &ss1));
+
+    stdin_buf = nm_str_buf_finalize_to_gbytes(&strbuf);
+    _fw_nft_call_sync(stdin_buf, NULL);
+}
+
+/*****************************************************************************/
+
 struct _NMFirewallConfig {
     FirewallTopic topic;
     char         *ip_iface;
@@ -697,6 +778,12 @@ struct _NMFirewallConfig {
             in_addr_t addr;
             guint8    plen;
         } ip4_shared;
+        struct {
+            int       addr_family;
+            guint32   fwmark;
+            NMIPAddr *addrs;
+            gsize     addrs_len;
+        } wireguard;
     };
 };
 
@@ -722,6 +809,35 @@ nm_firewall_config_new_ip4_shared(const char *ip_iface, in_addr_t addr, guint8 p
     return self;
 }
 
+NMFirewallConfig *
+nm_firewall_config_new_wireguard(const char     *ip_iface,
+                                 int             addr_family,
+                                 guint32         fwmark,
+                                 const NMIPAddr *addrs,
+                                 gsize           addrs_len)
+{
+    NMFirewallConfig *self;
+
+    nm_assert(ip_iface);
+    nm_assert_addr_family(addr_family);
+    nm_assert(addrs_len > 0);
+    nm_assert(addrs);
+
+    self  = g_slice_new(NMFirewallConfig);
+    *self = (NMFirewallConfig){
+        .topic    = FIREWALL_TOPIC_WIREGUARD,
+        .ip_iface = g_strdup(ip_iface),
+        .wireguard =
+            {
+                .addr_family = addr_family,
+                .fwmark      = fwmark,
+                .addrs       = nm_memdup(addrs, addrs_len * sizeof(addrs[0])),
+                .addrs_len   = addrs_len,
+            },
+    };
+    return self;
+}
+
 void
 nm_firewall_config_free(NMFirewallConfig *self)
 {
@@ -731,6 +847,9 @@ nm_firewall_config_free(NMFirewallConfig *self)
     switch (self->topic) {
     case FIREWALL_TOPIC_IP4_SHARED:
         goto out;
+    case FIREWALL_TOPIC_WIREGUARD:
+        g_free(self->wireguard.addrs);
+        goto out;
     }
     nm_assert_not_reached();
 
@@ -769,6 +888,25 @@ nm_firewall_config_apply(NMFirewallConfig *self, gboolean up)
             goto out_bug;
         }
         goto out_bug;
+    case FIREWALL_TOPIC_WIREGUARD:
+        switch (nm_firewall_utils_get_backend()) {
+        case NM_FIREWALL_BACKEND_IPTABLES:
+            /* XXX: Not implemented. */
+            return;
+        case NM_FIREWALL_BACKEND_NFTABLES:
+            _fw_nft_set_wireguard(up,
+                                  self->ip_iface,
+                                  self->wireguard.addr_family,
+                                  self->wireguard.fwmark,
+                                  self->wireguard.addrs,
+                                  self->wireguard.addrs_len);
+            return;
+        case NM_FIREWALL_BACKEND_NONE:
+            return;
+        case NM_FIREWALL_BACKEND_UNKNOWN:
+            goto out_bug;
+        }
+        goto out_bug;
     }
 out_bug:
     nm_assert_not_reached();

src/core/nm-firewall-utils.h

@@ -23,6 +23,12 @@ typedef struct _NMFirewallConfig NMFirewallConfig;
 NMFirewallConfig *
 nm_firewall_config_new_ip4_shared(const char *ip_iface, in_addr_t addr, guint8 plen);
 
+NMFirewallConfig *nm_firewall_config_new_wireguard(const char     *ip_iface,
+                                                   int             addr_family,
+                                                   guint32         fwmark,
+                                                   const NMIPAddr *addrs,
+                                                   gsize           addrs_len);
+
 void nm_firewall_config_free(NMFirewallConfig *self);
 
 void nm_firewall_config_apply(NMFirewallConfig *self, gboolean up);