diff --git a/src/dns-manager/nm-dns-manager.c b/src/dns-manager/nm-dns-manager.c index 8134f2f4a4..8690be8a36 100644 --- a/src/dns-manager/nm-dns-manager.c +++ b/src/dns-manager/nm-dns-manager.c @@ -1508,19 +1508,53 @@ _clear_plugin (NMDnsManager *self) return FALSE; } -static bool -_get_resconf_immutable (void) +static NMDnsManagerResolvConfManager +_check_resconf_immutable (NMDnsManagerResolvConfManager rc_manager) { + struct stat st; int fd, flags; bool immutable = FALSE; - fd = open (_PATH_RESCONF, O_RDONLY); - if (fd != -1) { - if (ioctl (fd, FS_IOC_GETFLAGS, &flags) != -1) - immutable = NM_FLAGS_HAS (flags, FS_IMMUTABLE_FL); - close (fd); + switch (rc_manager) { + case NM_DNS_MANAGER_RESOLV_CONF_MAN_UNKNOWN: + case NM_DNS_MANAGER_RESOLV_CONF_MAN_IMMUTABLE: + nm_assert_not_reached (); + /* fall-through */ + case NM_DNS_MANAGER_RESOLV_CONF_MAN_UNMANAGED: + return NM_DNS_MANAGER_RESOLV_CONF_MAN_UNMANAGED; + default: + + if (lstat (_PATH_RESCONF, &st) != 0) + return rc_manager; + + if (S_ISLNK (st.st_mode)) { + /* only regular files and directories can have extended file attributes. */ + switch (rc_manager) { + case NM_DNS_MANAGER_RESOLV_CONF_MAN_SYMLINK: + /* we don't care whether the link-target is immutable. + * If the symlink points to another file, rc-manager=symlink anyway backs off. + * Otherwise, we would only check whether our internal resolv.conf is immutable. */ + return NM_DNS_MANAGER_RESOLV_CONF_MAN_SYMLINK; + case NM_DNS_MANAGER_RESOLV_CONF_MAN_UNKNOWN: + case NM_DNS_MANAGER_RESOLV_CONF_MAN_UNMANAGED: + case NM_DNS_MANAGER_RESOLV_CONF_MAN_IMMUTABLE: + nm_assert_not_reached (); + /* fall-through */ + case NM_DNS_MANAGER_RESOLV_CONF_MAN_FILE: + case NM_DNS_MANAGER_RESOLV_CONF_MAN_RESOLVCONF: + case NM_DNS_MANAGER_RESOLV_CONF_MAN_NETCONFIG: + break; + } + } + + fd = open (_PATH_RESCONF, O_RDONLY); + if (fd != -1) { + if (ioctl (fd, FS_IOC_GETFLAGS, &flags) != -1) + immutable = NM_FLAGS_HAS (flags, FS_IMMUTABLE_FL); + close (fd); + } + return immutable ? NM_DNS_MANAGER_RESOLV_CONF_MAN_IMMUTABLE : rc_manager; } - return immutable; } NM_DEFINE_SINGLETON_GETTER (NMDnsManager, nm_dns_manager_get, NM_TYPE_DNS_MANAGER); @@ -1537,8 +1571,6 @@ init_resolv_conf_mode (NMDnsManager *self, gboolean force_reload_plugin) if (nm_streq0 (mode, "none")) rc_manager = NM_DNS_MANAGER_RESOLV_CONF_MAN_UNMANAGED; - else if (_get_resconf_immutable ()) - rc_manager = NM_DNS_MANAGER_RESOLV_CONF_MAN_IMMUTABLE; else { const char *man; @@ -1570,6 +1602,8 @@ again: } } + rc_manager = _check_resconf_immutable (rc_manager); + if (nm_streq0 (mode, "dnsmasq")) { if (force_reload_plugin || !NM_IS_DNS_DNSMASQ (priv->plugin)) { _clear_plugin (self);