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Message-ID: <20200818154230.14016-5-krzysztof.struczynski@huawei.com>
Date: Tue, 18 Aug 2020 17:42:14 +0200
From: <krzysztof.struczynski@...wei.com>
To: <linux-integrity@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
<containers@...ts.linux-foundation.org>,
<linux-security-module@...r.kernel.org>
CC: <zohar@...ux.ibm.com>, <stefanb@...ux.vnet.ibm.com>,
<sunyuqiong1988@...il.com>, <mkayaalp@...binghamton.edu>,
<dmitry.kasatkin@...il.com>, <serge@...lyn.com>,
<jmorris@...ei.org>, <christian@...uner.io>,
<silviu.vlasceanu@...wei.com>, <roberto.sassu@...wei.com>,
Krzysztof Struczynski <krzysztof.struczynski@...wei.com>
Subject: [RFC PATCH 14/30] ima: Add per namespace view of the measurement list
From: Krzysztof Struczynski <krzysztof.struczynski@...wei.com>
Modify ima securityfs interface, so that only measurement list entries
that belong to the given ima namespace are visible/counted. The initial
ima namespace is an exception, its processes have access to all
measurement list entries.
Signed-off-by: Krzysztof Struczynski <krzysztof.struczynski@...wei.com>
---
include/linux/ima.h | 1 +
security/integrity/ima/ima_fs.c | 57 ++++++++++++++++++++++++++----
security/integrity/ima/ima_init.c | 1 +
security/integrity/ima/ima_ns.c | 1 +
security/integrity/ima/ima_queue.c | 8 +++++
5 files changed, 61 insertions(+), 7 deletions(-)
diff --git a/include/linux/ima.h b/include/linux/ima.h
index df22143ffe30..d59ed38a4305 100644
--- a/include/linux/ima.h
+++ b/include/linux/ima.h
@@ -203,6 +203,7 @@ struct ima_namespace {
struct ima_policy_data *policy_data;
struct integrity_iint_tree *iint_tree;
struct list_head *measurements;
+ atomic_long_t ml_len; /* number of stored measurements in the list */
} __randomize_layout;
extern struct ima_namespace init_ima_ns;
diff --git a/security/integrity/ima/ima_fs.c b/security/integrity/ima/ima_fs.c
index 4758e14c4a7b..e2893f0b0f31 100644
--- a/security/integrity/ima/ima_fs.c
+++ b/security/integrity/ima/ima_fs.c
@@ -63,7 +63,9 @@ static ssize_t ima_show_measurements_count(struct file *filp,
char __user *buf,
size_t count, loff_t *ppos)
{
- return ima_show_htable_value(buf, count, ppos, &ima_htable.len);
+ struct ima_namespace *ima_ns = get_current_ns();
+
+ return ima_show_htable_value(buf, count, ppos, &ima_ns->ml_len);
}
@@ -77,10 +79,36 @@ static void *ima_measurements_start(struct seq_file *m, loff_t *pos)
{
loff_t l = *pos;
struct ima_queue_entry *qe;
+ struct ima_namespace *ima_ns = get_current_ns();
+ unsigned int ns_id = get_ns_id(ima_ns);
+
+ if (ima_ns == &init_ima_ns) {
+ /* we need a lock since pos could point beyond last element */
+ rcu_read_lock();
+ list_for_each_entry_rcu(qe, &ima_measurements, later) {
+ if (!l--) {
+ rcu_read_unlock();
+ return qe;
+ }
+ }
+ rcu_read_unlock();
+ return NULL;
+ }
- /* we need a lock since pos could point beyond last element */
rcu_read_lock();
- list_for_each_entry_rcu(qe, &ima_measurements, later) {
+ qe = list_next_or_null_rcu(&ima_measurements,
+ ima_ns->measurements,
+ struct ima_queue_entry,
+ later);
+ if (!qe) {
+ rcu_read_unlock();
+ return NULL;
+ }
+
+ list_for_each_entry_from_rcu(qe, &ima_measurements, later) {
+ if (ns_id != qe->entry->ns_id)
+ continue;
+
if (!l--) {
rcu_read_unlock();
return qe;
@@ -93,12 +121,27 @@ static void *ima_measurements_start(struct seq_file *m, loff_t *pos)
static void *ima_measurements_next(struct seq_file *m, void *v, loff_t *pos)
{
struct ima_queue_entry *qe = v;
+ struct ima_namespace *ima_ns = get_current_ns();
+ unsigned int ns_id = get_ns_id(ima_ns);
+
+ if (ima_ns == &init_ima_ns) {
+ /* lock protects when reading beyond last element
+ * against concurrent list-extension
+ */
+ rcu_read_lock();
+ qe = list_entry_rcu(qe->later.next, struct ima_queue_entry,
+ later);
+ rcu_read_unlock();
+ (*pos)++;
+
+ return (&qe->later == &ima_measurements) ? NULL : qe;
+ }
- /* lock protects when reading beyond last element
- * against concurrent list-extension
- */
rcu_read_lock();
- qe = list_entry_rcu(qe->later.next, struct ima_queue_entry, later);
+ list_for_each_entry_continue_rcu(qe, &ima_measurements, later) {
+ if (ns_id == qe->entry->ns_id)
+ break;
+ }
rcu_read_unlock();
(*pos)++;
diff --git a/security/integrity/ima/ima_init.c b/security/integrity/ima/ima_init.c
index 2100ee341dfc..ac9509d8c0f0 100644
--- a/security/integrity/ima/ima_init.c
+++ b/security/integrity/ima/ima_init.c
@@ -36,6 +36,7 @@ struct ima_namespace init_ima_ns = {
.policy_data = &init_policy_data,
.iint_tree = &init_iint_tree,
.measurements = &ima_measurements,
+ .ml_len = ATOMIC_LONG_INIT(0),
};
EXPORT_SYMBOL(init_ima_ns);
diff --git a/security/integrity/ima/ima_ns.c b/security/integrity/ima/ima_ns.c
index f331187a4d3c..81de492baa99 100644
--- a/security/integrity/ima/ima_ns.c
+++ b/security/integrity/ima/ima_ns.c
@@ -126,6 +126,7 @@ static struct ima_namespace *clone_ima_ns(struct user_namespace *user_ns,
ns->user_ns = get_user_ns(user_ns);
ns->ucounts = ucounts;
ns->frozen = false;
+ atomic_long_set(&ns->ml_len, 0);
rwlock_init(&ns->iint_tree->lock);
ns->iint_tree->root = RB_ROOT;
diff --git a/security/integrity/ima/ima_queue.c b/security/integrity/ima/ima_queue.c
index bd890778c5be..ec5b3ca3ef92 100644
--- a/security/integrity/ima/ima_queue.c
+++ b/security/integrity/ima/ima_queue.c
@@ -227,6 +227,14 @@ int ima_add_template_entry(struct ima_template_entry *entry, int violation,
goto out;
}
+ /* Initial ima namespace has access to all measurement list entries,
+ * therefore always increment its measurement list length. Other
+ * namespaces can see only their own entries.
+ */
+ if (ima_ns != &init_ima_ns)
+ atomic_long_inc(&ima_ns->ml_len);
+ atomic_long_inc(&init_ima_ns.ml_len);
+
if (violation) /* invalidate pcr */
digests_arg = digests;
--
2.20.1
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