imans: Use initial ima namespace domain tag when IMANS is disabled.

hulk inclusion
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I4C9AE
CVE: NA

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As part of the imans support, a key domain tag is added to the search
criteria in digsig module. When IMA Namespace is disabled, the initial
ima namespace domain tag should be used instead of nsproxy.
Signed-off-by: NAjo Jose Panoor <ajo.jose.panoor@huawei.com>
Reviewed-by: NZhang Tianxing <zhangtianxing3@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

security/integrity/digsig.c

@@ -74,8 +74,11 @@ static struct key_tag *domain_tag_from_id(const unsigned int id)
 		return ERR_PTR(-EINVAL);
 
 	if (id == INTEGRITY_KEYRING_IMA)
+#ifdef CONFIG_IMA_NS
 		return current->nsproxy->ima_ns->key_domain;
-
+#else
+		return init_ima_ns.key_domain;
+#endif
 	return NULL;
 }