[RFC][PATCH 2/2] ima: created new ima template ima-cgpath for Kubernates' pods attestation

[Enrico Bravi <enrico.bravi@xxxxxxxxx>]

This patch depends on patch "created new ima template ima-dep-cgn for
OCI containers attestation".
Created a new ima template ima-cgpath (dep|cg-path|d-ng|n-ng) based on a
new ima template field:
	- cgpath: subsys_id=1 cgroup complete path (cgroup_path()) of
		  the process that generated a specific measurement event.
		  In the case of containerized processes created by Kubernetes
		  this field contains both the identifier of the container in
		  which the process runs, and the identifier of the pod to which
		  the container belongs.

This template permits to separately attest the host system and the Kubernetes' pods
running on it. In this way the verifier will be able to communicate the pod ID, in
case of compromission, to Kubernetes in order to reschedule it.

Signed-off-by: Silvia Sisinni <silvia.sisinni@xxxxxxxxx>
Signed-off-by: Enrico Bravi <enrico.bravi@xxxxxxxxx>
---
 security/integrity/ima/Kconfig            |  3 +++
 security/integrity/ima/ima_template.c     |  3 +++
 security/integrity/ima/ima_template_lib.c | 31 +++++++++++++++++++++++
 security/integrity/ima/ima_template_lib.h |  2 ++
 4 files changed, 39 insertions(+)

diff --git a/security/integrity/ima/Kconfig b/security/integrity/ima/Kconfig
index b85b2c757812..abbe3c554276 100644
--- a/security/integrity/ima/Kconfig
+++ b/security/integrity/ima/Kconfig
@@ -78,6 +78,8 @@ choice
 		bool "ima-sig"
 	config IMA_DEP_CGN_TEMPLATE
 		bool "ima-dep-cgn"
+	config IMA_CGPATH_TEMPLATE
+		bool "ima-cgpath"
 endchoice
 
 config IMA_DEFAULT_TEMPLATE
@@ -86,6 +88,7 @@ config IMA_DEFAULT_TEMPLATE
 	default "ima-ng" if IMA_NG_TEMPLATE
 	default "ima-sig" if IMA_SIG_TEMPLATE
 	default "ima-dep-cgn" if IMA_DEP_CGN_TEMPLATE
+	default "ima-cgpath" if IMA_CGPATH_TEMPLATE
 
 choice
 	prompt "Default integrity hash algorithm"
diff --git a/security/integrity/ima/ima_template.c b/security/integrity/ima/ima_template.c
index 0862a5e8efc4..301d14e4c650 100644
--- a/security/integrity/ima/ima_template.c
+++ b/security/integrity/ima/ima_template.c
@@ -27,6 +27,7 @@ static struct ima_template_desc builtin_templates[] = {
 	{.name = "evm-sig",
 	 .fmt = "d-ng|n-ng|evmsig|xattrnames|xattrlengths|xattrvalues|iuid|igid|imode"},
 	{.name = "ima-dep-cgn", .fmt = "dep|cgn|d-ng|n-ng"},
+	{.name = "ima-cgpath", .fmt = "dep|cg-path|d-ng|n-ng"},
 	{.name = "", .fmt = ""},	/* placeholder for a custom format */
 };
 
@@ -74,6 +75,8 @@ static const struct ima_template_field supported_fields[] = {
 	 .field_show = ima_show_template_string},
 	{.field_id = "dep", .field_init = ima_eventdep_init,
 	 .field_show = ima_show_template_string},
+	{.field_id = "cg-path", .field_init = ima_eventcg_path_init,
+	 .field_show = ima_show_template_string},
 };
 
 /*
diff --git a/security/integrity/ima/ima_template_lib.c b/security/integrity/ima/ima_template_lib.c
index d8bb91b2e73c..bbedb29c3051 100644
--- a/security/integrity/ima/ima_template_lib.c
+++ b/security/integrity/ima/ima_template_lib.c
@@ -838,3 +838,34 @@ int ima_eventdep_init(struct ima_event_data *event_data,
 
 	return rc;
 }
+
+/*
+ * ima_eventcg_path_init - include the current task's subsys_id=1 cgroup path as part of the
+ * template data
+ */
+int ima_eventcg_path_init(struct ima_event_data *event_data,
+				struct ima_field_data *field_data)
+{
+	char *cgroup_path_str = NULL;
+	struct cgroup *cgroup = NULL;
+	int rc = 0;
+
+	cgroup_path_str = kmalloc(PATH_MAX, GFP_KERNEL);
+
+	if (!cgroup_path_str)
+		return -ENOMEM;
+
+	cgroup = task_cgroup(current, 1);
+	if (!cgroup)
+		goto out;
+
+	rc = cgroup_path(cgroup, cgroup_path_str, PATH_MAX);
+	if (!rc)
+		goto out;
+
+	rc = ima_write_template_field_data(cgroup_path_str, strlen(cgroup_path_str), DATA_FMT_STRING, field_data);
+	kfree(cgroup_path_str);
+	return rc;
+out:
+	return ima_write_template_field_data("-", 1, DATA_FMT_STRING, field_data);
+}
diff --git a/security/integrity/ima/ima_template_lib.h b/security/integrity/ima/ima_template_lib.h
index e5b1166d7ca4..7d58c34ca639 100644
--- a/security/integrity/ima/ima_template_lib.h
+++ b/security/integrity/ima/ima_template_lib.h
@@ -70,4 +70,6 @@ int ima_eventcgn_init(struct ima_event_data *event_data,
 			struct ima_field_data *field_data);
 int ima_eventdep_init(struct ima_event_data *event_data,
 			struct ima_field_data *field_data);
+int ima_eventcg_path_init(struct ima_event_data *event_data,
+				struct ima_field_data *field_data);
 #endif /* __LINUX_IMA_TEMPLATE_LIB_H */
-- 
2.25.1