[PATCH v5 08/16] ima: Move measurement list related variables into ima_namespace

Stefan Berger
2021-12-08T22:18:33Z

Move measurement list related variables into the ima_namespace. This way a
front-end like SecurityFS can show the measurement list inside an IMA
namespace.

Implement ima_free_measurements() to free a list of measurements
and call it when an IMA namespace is deleted.

Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>
---
include/linux/ima.h | 2 ++
security/integrity/ima/ima.h | 4 +--
security/integrity/ima/ima_fs.c | 6 +++--
security/integrity/ima/ima_init_ima_ns.c | 5 ++++
security/integrity/ima/ima_ns.c | 1 +
security/integrity/ima/ima_queue.c | 33 ++++++++++++++----------
6 files changed, 33 insertions(+), 18 deletions(-)

diff --git a/include/linux/ima.h b/include/linux/ima.h
index 080edecc0ea1..2ce801bfc449 100644
--- a/include/linux/ima.h
+++ b/include/linux/ima.h
@@ -259,6 +259,8 @@ struct ima_namespace {
int ima_policy_flag;

struct ima_h_table ima_htable;
+ struct list_head ima_measurements;
+ unsigned long binary_runtime_size;
};

extern struct ima_namespace init_ima_ns;
diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h
index a7e6c8fb152a..bb9763cd5fb1 100644
--- a/security/integrity/ima/ima.h
+++ b/security/integrity/ima/ima.h
@@ -104,7 +104,6 @@ struct ima_queue_entry {
struct list_head later; /* place in ima_measurements list */
struct ima_template_entry *entry;
};
-extern struct list_head ima_measurements; /* list of all measurements */

/* Some details preceding the binary serialized measurement list */
struct ima_kexec_hdr {
@@ -168,8 +167,9 @@ int ima_restore_measurement_entry(struct ima_namespace *ns,
struct ima_template_entry *entry);
int ima_restore_measurement_list(struct ima_namespace *ns,
loff_t bufsize, void *buf);
+void ima_free_measurements(struct ima_namespace *ns);
int ima_measurements_show(struct seq_file *m, void *v);
-unsigned long ima_get_binary_runtime_size(void);
+unsigned long ima_get_binary_runtime_size(struct ima_namespace *ns);
int ima_init_template(void);
void ima_init_template_list(void);
int __init ima_init_digests(void);
diff --git a/security/integrity/ima/ima_fs.c b/security/integrity/ima/ima_fs.c
index e37c973a94c6..38b1c26479b3 100644
--- a/security/integrity/ima/ima_fs.c
+++ b/security/integrity/ima/ima_fs.c
@@ -80,12 +80,13 @@ static const struct file_operations ima_measurements_count_ops = {
/* returns pointer to hlist_node */
static void *ima_measurements_start(struct seq_file *m, loff_t *pos)
{
+ struct ima_namespace *ns = get_current_ns();
loff_t l = *pos;
struct ima_queue_entry *qe;

/* we need a lock since pos could point beyond last element */
rcu_read_lock();
- list_for_each_entry_rcu(qe, &ima_measurements, later) {
+ list_for_each_entry_rcu(qe, &ns->ima_measurements, later) {
if (!l--) {
rcu_read_unlock();
return qe;
@@ -97,6 +98,7 @@ 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_namespace *ns = get_current_ns();
struct ima_queue_entry *qe = v;

/* lock protects when reading beyond last element
@@ -107,7 +109,7 @@ static void *ima_measurements_next(struct seq_file *m, void *v, loff_t *pos)
rcu_read_unlock();
(*pos)++;

- return (&qe->later == &ima_measurements) ? NULL : qe;
+ return (&qe->later == &ns->ima_measurements) ? NULL : qe;
}

static void ima_measurements_stop(struct seq_file *m, void *v)
diff --git a/security/integrity/ima/ima_init_ima_ns.c b/security/integrity/ima/ima_init_ima_ns.c
index 32ff7e271024..b097aad7b156 100644
--- a/security/integrity/ima/ima_init_ima_ns.c
+++ b/security/integrity/ima/ima_init_ima_ns.c
@@ -43,6 +43,11 @@ int ima_init_namespace(struct ima_namespace *ns)
atomic_long_set(&ns->ima_htable.len, 0);
atomic_long_set(&ns->ima_htable.violations, 0);
memset(&ns->ima_htable.queue, 0, sizeof(ns->ima_htable.queue));
+ INIT_LIST_HEAD(&ns->ima_measurements);
+ if (IS_ENABLED(CONFIG_IMA_KEXEC) && ns == &init_ima_ns)
+ ns->binary_runtime_size = 0;
+ else
+ ns->binary_runtime_size = ULONG_MAX;

return 0;
}
diff --git a/security/integrity/ima/ima_ns.c b/security/integrity/ima/ima_ns.c
index 9c628ab2978b..6a0632806cdb 100644
--- a/security/integrity/ima/ima_ns.c
+++ b/security/integrity/ima/ima_ns.c
@@ -59,6 +59,7 @@ static void destroy_ima_ns(struct ima_namespace *ns)
pr_debug("DESTROY ima_ns: 0x%p\n", ns);
ima_free_policy_rules(ns);
free_ns_status_cache(ns);
+ ima_free_measurements(ns);
kmem_cache_free(imans_cachep, ns);
}

diff --git a/security/integrity/ima/ima_queue.c b/security/integrity/ima/ima_queue.c
index 373154039b91..f15f776918ec 100644
--- a/security/integrity/ima/ima_queue.c
+++ b/security/integrity/ima/ima_queue.c
@@ -25,13 +25,6 @@
/* pre-allocated array of tpm_digest structures to extend a PCR */
static struct tpm_digest *digests;

-LIST_HEAD(ima_measurements); /* list of all measurements */
-#ifdef CONFIG_IMA_KEXEC
-static unsigned long binary_runtime_size;
-#else
-static unsigned long binary_runtime_size = ULONG_MAX;
-#endif
-
/* mutex protects atomicity of extending measurement list
* and extending the TPM PCR aggregate. Since tpm_extend can take
* long (and the tpm driver uses a mutex), we can't use the spinlock.
@@ -107,7 +100,7 @@ static int ima_add_digest_entry(struct ima_namespace *ns,
qe->entry = entry;

INIT_LIST_HEAD(&qe->later);
- list_add_tail_rcu(&qe->later, &ima_measurements);
+ list_add_tail_rcu(&qe->later, &ns->ima_measurements);

atomic_long_inc(&ns->ima_htable.len);
if (update_htable) {
@@ -116,12 +109,12 @@ static int ima_add_digest_entry(struct ima_namespace *ns,
} else
INIT_HLIST_NODE(&qe->hnext);

- if (binary_runtime_size != ULONG_MAX) {
+ if (ns->binary_runtime_size != ULONG_MAX) {
int size;

size = get_binary_runtime_size(entry);
- binary_runtime_size = (binary_runtime_size < ULONG_MAX - size) ?
- binary_runtime_size + size : ULONG_MAX;
+ ns->binary_runtime_size = (ns->binary_runtime_size < ULONG_MAX - size) ?
+ ns->binary_runtime_size + size : ULONG_MAX;
}
return 0;
}
@@ -131,12 +124,12 @@ static int ima_add_digest_entry(struct ima_namespace *ns,
* entire binary_runtime_measurement list, including the ima_kexec_hdr
* structure.
*/
-unsigned long ima_get_binary_runtime_size(void)
+unsigned long ima_get_binary_runtime_size(struct ima_namespace *ns)
{
- if (binary_runtime_size >= (ULONG_MAX - sizeof(struct ima_kexec_hdr)))
+ if (ns->binary_runtime_size >= (ULONG_MAX - sizeof(struct ima_kexec_hdr)))
return ULONG_MAX;
else
- return binary_runtime_size + sizeof(struct ima_kexec_hdr);
+ return ns->binary_runtime_size + sizeof(struct ima_kexec_hdr);
}

static int ima_pcr_extend(struct tpm_digest *digests_arg, int pcr)
@@ -217,6 +210,18 @@ int ima_restore_measurement_entry(struct ima_namespace *ns,
return result;
}

+void ima_free_measurements(struct ima_namespace *ns)
+{
+ struct ima_queue_entry *qe, *tmp;
+
+ list_for_each_entry_safe(qe, tmp, &ns->ima_measurements, later) {
+ list_del(&qe->later);
+ if (!hlist_unhashed(&qe->hnext))
+ hlist_del(&qe->hnext);
+ kfree(qe);
+ }
+}
+
int __init ima_init_digests(void)
{
u16 digest_size;
--
2.31.1