ima_dump_measurement_list() is called from ima_add_kexec_buffer() during
kexec 'load', which may result in loss of IMA measurements between kexec
'load' and 'execute'. It needs to be called during kexec 'execute'.
Implement ima_update_kexec_buffer(), to be called during kexec 'execute'.
Move ima_dump_measurement_list() function call from ima_add_kexec_buffer()
to ima_update_kexec_buffer(). Make the needed variables global for
accessibility during kexec 'load' and 'execute'. Implement and call
ima_measurements_suspend() and ima_measurements_resume() to help ensure
the integrity of the IMA log during copy. Add a reboot notifier_block to
trigger ima_update_kexec_buffer() during kexec soft-reboot. Exclude ima
segment from calculating and storing digest in function
kexec_calculate_store_digests(), since ima segment can be modified
after the digest is computed during kexec 'load'.
Signed-off-by: Tushar Sugandhi <tusha...@linux.microsoft.com>
---
include/linux/kexec.h | 3 ++
kernel/kexec_file.c | 8 ++++
security/integrity/ima/ima.h | 2 +
security/integrity/ima/ima_kexec.c | 61 +++++++++++++++++++++++++-----
security/integrity/ima/ima_queue.c | 19 ++++++++++
5 files changed, 84 insertions(+), 9 deletions(-)
diff --git a/include/linux/kexec.h b/include/linux/kexec.h
index 22b5cd24f581..fd94404acc66 100644
--- a/include/linux/kexec.h
+++ b/include/linux/kexec.h
@@ -366,6 +366,9 @@ struct kimage {
phys_addr_t ima_buffer_addr;
size_t ima_buffer_size;
+
+ unsigned long ima_segment_index;
+ bool is_ima_segment_index_set;
#endif
/* Core ELF header buffer */
diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
index f989f5f1933b..bf758fd5062c 100644
--- a/kernel/kexec_file.c
+++ b/kernel/kexec_file.c
@@ -734,6 +734,14 @@ static int kexec_calculate_store_digests(struct kimage
*image)
if (ksegment->kbuf == pi->purgatory_buf)
continue;
+ /*
+ * Skip the segment if ima_segment_index is set and matches
+ * the current index
+ */
+ if (image->is_ima_segment_index_set &&
+ i == image->ima_segment_index)
+ continue;
+
ret = crypto_shash_update(desc, ksegment->kbuf,
ksegment->bufsz);
if (ret)
diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h
index c29db699c996..49a6047dd8eb 100644
--- a/security/integrity/ima/ima.h
+++ b/security/integrity/ima/ima.h
@@ -161,6 +161,8 @@ bool ima_template_has_modsig(const struct ima_template_desc
*ima_template);
int ima_restore_measurement_entry(struct ima_template_entry *entry);
int ima_restore_measurement_list(loff_t bufsize, void *buf);
int ima_measurements_show(struct seq_file *m, void *v);
+void ima_measurements_suspend(void);
+void ima_measurements_resume(void);
unsigned long ima_get_binary_runtime_size(void);
int ima_init_template(void);
void ima_init_template_list(void);
diff --git a/security/integrity/ima/ima_kexec.c
b/security/integrity/ima/ima_kexec.c
index ae27101d0615..0063d5e7b634 100644
--- a/security/integrity/ima/ima_kexec.c
+++ b/security/integrity/ima/ima_kexec.c
@@ -16,6 +16,8 @@
#ifdef CONFIG_IMA_KEXEC
struct seq_file ima_kexec_file;
+static void *ima_kexec_buffer;
+static size_t kexec_segment_size;
void ima_free_kexec_file_buf(struct seq_file *sf)
{
@@ -120,7 +122,6 @@ void ima_add_kexec_buffer(struct kimage *image)
/* use more understandable variable names than defined in kbuf */
void *kexec_buffer = NULL;
size_t kexec_buffer_size;
- size_t kexec_segment_size;
int ret;
/*
@@ -145,17 +146,10 @@ void ima_add_kexec_buffer(struct kimage *image)
return;
}
- ret = ima_dump_measurement_list(&kexec_buffer_size, &kexec_buffer,
- kexec_segment_size);
- if (ret < 0) {
- pr_err("%s: Failed to dump IMA measurements. Error:%d.\n",
- __func__, ret);
- return;
- }
-
kbuf.buffer = kexec_buffer;
kbuf.bufsz = kexec_buffer_size;
kbuf.memsz = kexec_segment_size;
+ image->is_ima_segment_index_set = false;
ret = kexec_add_buffer(&kbuf);
if (ret) {
pr_err("Error passing over kexec measurement buffer.\n");
@@ -166,10 +160,59 @@ void ima_add_kexec_buffer(struct kimage *image)
image->ima_buffer_addr = kbuf.mem;
image->ima_buffer_size = kexec_segment_size;
image->ima_buffer = kexec_buffer;
+ image->ima_segment_index = image->nr_segments - 1;
+ image->is_ima_segment_index_set = true;
pr_debug("kexec measurement buffer for the loaded kernel at 0x%lx.\n",
kbuf.mem);
}
+
+/*
+ * Called during kexec execute so that IMA can update the measurement list.
+ */
+static int ima_update_kexec_buffer(struct notifier_block *self,
+ unsigned long action, void *data)
+{
+ void *buf = NULL;
+ size_t buf_size;
+ bool resume = false;
+ int ret = NOTIFY_OK;
+
+ if (!kexec_in_progress) {
+ pr_info("%s: No kexec in progress.\n", __func__);
+ return ret;
+ }
+
+ if (!ima_kexec_buffer) {
+ pr_err("%s: Kexec buffer not set.\n", __func__);
+ return ret;
+ }
+
+ ima_measurements_suspend();
+
+ ret = ima_dump_measurement_list(&buf_size, &buf,
+ kexec_segment_size);
+
+ if (!buf) {
+ pr_err("%s: Dump measurements failed. Error:%d\n",
+ __func__, ret);
+ resume = true;
+ goto out;
+ }
+ memcpy(ima_kexec_buffer, buf, buf_size);
+out:
+ ima_kexec_buffer = NULL;
+
+ if (resume)
+ ima_measurements_resume();
+
+ return ret;
+}
+
+struct notifier_block update_buffer_nb = {
+ .notifier_call = ima_update_kexec_buffer,
+};
+
#endif /* IMA_KEXEC */
/*
diff --git a/security/integrity/ima/ima_queue.c
b/security/integrity/ima/ima_queue.c
index 532da87ce519..cb9abc02a304 100644
--- a/security/integrity/ima/ima_queue.c
+++ b/security/integrity/ima/ima_queue.c
@@ -44,6 +44,11 @@ struct ima_h_table ima_htable = {
*/
static DEFINE_MUTEX(ima_extend_list_mutex);
+/*
+ * Used internally by the kernel to suspend-resume ima measurements.
+ */
+static atomic_t suspend_ima_measurements;
+
/* lookup up the digest value in the hash table, and return the entry */
static struct ima_queue_entry *ima_lookup_digest_entry(u8 *digest_value,
int pcr)
@@ -148,6 +153,20 @@ static int ima_pcr_extend(struct tpm_digest *digests_arg,
int pcr)
return result;
}
+void ima_measurements_suspend(void)
+{
+ mutex_lock(&ima_extend_list_mutex);
+ atomic_set(&suspend_ima_measurements, 1);
+ mutex_unlock(&ima_extend_list_mutex);
+}
+
+void ima_measurements_resume(void)
+{
+ mutex_lock(&ima_extend_list_mutex);
+ atomic_set(&suspend_ima_measurements, 0);
+ mutex_unlock(&ima_extend_list_mutex);
+}
+
/*
* Add template entry to the measurement list and hash table, and
* extend the pcr.
--
2.25.1
