[PATCH v14 06/26] ima: Move measurement list related variables into ima_namespace

From: Stefan Berger
Date: Thu Sep 15 2022 - 15:34:20 EST

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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.

Also, in order for kexec to allocate memory for the existing
measurement list, the measurement list memory size is stored in the
binary_runtime_size variable. To avoid special-casing init_ima_ns, as
much as possible, move it into the ima_namespace.

Signed-off-by: Stefan Berger <stefanb@xxxxxxxxxxxxx>
Reviewed-by: Mimi Zohar <zohar@xxxxxxxxxxxxx>
Reviewed-by: Serge Hallyn <serge@xxxxxxxxxx>
---
security/integrity/ima/ima.h | 5 +++--
security/integrity/ima/ima_fs.c | 6 ++++--
security/integrity/ima/ima_init_ima_ns.c | 5 +++++
security/integrity/ima/ima_kexec.c | 12 ++++++-----
security/integrity/ima/ima_queue.c | 27 +++++++++++-------------
5 files changed, 31 insertions(+), 24 deletions(-)

diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h
index 78798cfcf46c..82e8af2bf698 100644
--- a/security/integrity/ima/ima.h
+++ b/security/integrity/ima/ima.h
@@ -106,7 +106,6 @@ 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 {
@@ -136,6 +135,8 @@ struct ima_namespace {
struct ima_rule_entry *arch_policy_entry;

struct ima_h_table ima_htable;
+ struct list_head ima_measurements; /* list of all measurements */
+ unsigned long binary_runtime_size; /* used by init_ima_ns */
} __randomize_layout;
extern struct ima_namespace init_ima_ns;

@@ -186,7 +187,7 @@ int ima_restore_measurement_entry(struct ima_namespace *ns,
int ima_restore_measurement_list(struct ima_namespace *ns,
loff_t bufsize, void *buf);
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 dca7fe32d65e..5ef0e2b2cf64 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 = &init_ima_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 = &init_ima_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 1945fa8cfc4d..a7477072c587 100644
--- a/security/integrity/ima/ima_init_ima_ns.c
+++ b/security/integrity/ima/ima_init_ima_ns.c
@@ -20,6 +20,11 @@ static 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_kexec.c b/security/integrity/ima/ima_kexec.c
index 7559c3840f74..eed147bdc83e 100644
--- a/security/integrity/ima/ima_kexec.c
+++ b/security/integrity/ima/ima_kexec.c
@@ -15,7 +15,8 @@
#include "ima.h"

#ifdef CONFIG_IMA_KEXEC
-static int ima_dump_measurement_list(unsigned long *buffer_size, void **buffer,
+static int ima_dump_measurement_list(struct ima_namespace *ns,
+ unsigned long *buffer_size, void **buffer,
unsigned long segment_size)
{
struct ima_queue_entry *qe;
@@ -36,7 +37,7 @@ static int ima_dump_measurement_list(unsigned long *buffer_size, void **buffer,

memset(&khdr, 0, sizeof(khdr));
khdr.version = 1;
- list_for_each_entry_rcu(qe, &ima_measurements, later) {
+ list_for_each_entry_rcu(qe, &ns->ima_measurements, later) {
if (file.count < file.size) {
khdr.count++;
ima_measurements_show(&file, qe);
@@ -84,6 +85,7 @@ void ima_add_kexec_buffer(struct kimage *image)
struct kexec_buf kbuf = { .image = image, .buf_align = PAGE_SIZE,
.buf_min = 0, .buf_max = ULONG_MAX,
.top_down = true };
+ struct ima_namespace *ns = &init_ima_ns;
unsigned long binary_runtime_size;

/* use more understandable variable names than defined in kbuf */
@@ -96,11 +98,11 @@ void ima_add_kexec_buffer(struct kimage *image)
* Reserve an extra half page of memory for additional measurements
* added during the kexec load.
*/
- binary_runtime_size = ima_get_binary_runtime_size();
+ binary_runtime_size = ima_get_binary_runtime_size(ns);
if (binary_runtime_size >= ULONG_MAX - PAGE_SIZE)
kexec_segment_size = ULONG_MAX;
else
- kexec_segment_size = ALIGN(ima_get_binary_runtime_size() +
+ kexec_segment_size = ALIGN(ima_get_binary_runtime_size(ns) +
PAGE_SIZE / 2, PAGE_SIZE);
if ((kexec_segment_size == ULONG_MAX) ||
((kexec_segment_size >> PAGE_SHIFT) > totalram_pages() / 2)) {
@@ -108,7 +110,7 @@ void ima_add_kexec_buffer(struct kimage *image)
return;
}

- ima_dump_measurement_list(&kexec_buffer_size, &kexec_buffer,
+ ima_dump_measurement_list(ns, &kexec_buffer_size, &kexec_buffer,
kexec_segment_size);
if (!kexec_buffer) {
pr_err("Not enough memory for the kexec measurement buffer.\n");
diff --git a/security/integrity/ima/ima_queue.c b/security/integrity/ima/ima_queue.c
index 43961d5cd2ef..0355c2b0932c 100644
--- a/security/integrity/ima/ima_queue.c
+++ b/security/integrity/ima/ima_queue.c
@@ -24,13 +24,6 @@
/* 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.
@@ -100,7 +93,7 @@ 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) {
@@ -110,12 +103,14 @@ static int ima_add_digest_entry(struct ima_namespace *ns,
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;
}
@@ -123,14 +118,16 @@ static int ima_add_digest_entry(struct ima_namespace *ns,
/*
* Return the amount of memory required for serializing the
* entire binary_runtime_measurement list, including the ima_kexec_hdr
- * structure.
+ * structure. Carrying the measurement list across kexec is limited
+ * to init_ima_ns.
*/
-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)
--
2.36.1

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