network: fix ipv6 tunnel encapsulation limit (#19087)

The encapsulation limit of IPv6 tunnel can not be set to 4, which is the default value of the encapsulation limit.

TODO

@@ -22,6 +22,17 @@ Janitorial Clean-ups:
 
 Features:
 
+* maybe add a tool that displays most recent journal logs as QR code to scan
+  off screen and run it automatically on boot failures, emergency logs and
+  such. Use DRM APIs directly, see
+  https://github.com/dvdhrm/docs/blob/master/drm-howto/modeset.c for an example
+  for doing that.
+
+* pass systemd-detect-virt result to generators as env var. Modifying behaviour
+  based on whether we are virtualized or not is a pretty common thing, hence
+  maybe just pass that info along for free in an env var. We cache the result
+  anyway, so it's basically free.
+
 * systemd-repart: read LUKS encryption key from $CREDENTIALS_PATH
 
 * introduce /dev/disk/root/* symlinks that allow referencing partitions on the

src/basic/blockdev-util.c

@@ -68,7 +68,7 @@ int get_block_device(const char *path, dev_t *ret) {
         /* Gets the block device directly backing a file system. If the block device is encrypted, returns
          * the device mapper block device. */
 
-        fd = open(path, O_NOFOLLOW|O_CLOEXEC);
+        fd = open(path, O_RDONLY|O_NOFOLLOW|O_CLOEXEC);
         if (fd < 0)
                 return -errno;
 

src/network/netdev/tunnel.c

@@ -389,7 +389,7 @@ static int netdev_ip6tnl_fill_message_create(NetDev *netdev, Link *link, sd_netl
         if (t->allow_localremote >= 0)
                 SET_FLAG(t->flags, IP6_TNL_F_ALLOW_LOCAL_REMOTE, t->allow_localremote);
 
-        if (t->encap_limit != IPV6_DEFAULT_TNL_ENCAP_LIMIT) {
+        if (t->encap_limit != 0) {
                 r = sd_netlink_message_append_u8(m, IFLA_IPTUN_ENCAP_LIMIT, t->encap_limit);
                 if (r < 0)
                         return log_netdev_error_errno(netdev, r, "Could not append IFLA_IPTUN_ENCAP_LIMIT attribute: %m");

src/partition/repart.c

@@ -2994,8 +2994,6 @@ static int partition_acquire_label(Context *context, Partition *p, char **ret) {
                         break;
 
                 label = mfree(label);
-
-
                 if (asprintf(&label, "%s-%u", prefix, ++k) < 0)
                         return log_oom();
         }