In preparation for serializing the binary_runtime_measurements, this patch
maintains the amount of memory required.
Changelog v3:
- include the ima_kexec_hdr size in the binary_runtime_measurement size.
Signed-off-by: Mimi Zohar <zohar at linux.vnet.ibm.com>
---
security/integrity/ima/Kconfig | 12 +++++++++
security/integrity/ima/ima.h | 1 +
security/integrity/ima/ima_queue.c | 53 ++++++++++++++++++++++++++++++++++++--
3 files changed, 64 insertions(+), 2 deletions(-)
diff --git a/security/integrity/ima/Kconfig b/security/integrity/ima/Kconfig
index 5487827..1c5a1c2 100644
--- a/security/integrity/ima/Kconfig
+++ b/security/integrity/ima/Kconfig
@@ -27,6 +27,18 @@ config IMA
to learn more about IMA.
If unsure, say N.
+config IMA_KEXEC
+ bool "Enable carrying the IMA measurement list across a soft boot"
+ depends on IMA && TCG_TPM && KEXEC_FILE
+ default n
+ help
+ TPM PCRs are only reset on a hard reboot. In order to validate
+ a TPM's quote after a soft boot, the IMA measurement list of the
+ running kernel must be saved and restored on boot.
+
+ Depending on the IMA policy, the measurement list can grow to
+ be very large.
+
config IMA_MEASURE_PCR_IDX
int
depends on IMA
diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h
index e7b3755..f9cd08e 100644
--- a/security/integrity/ima/ima.h
+++ b/security/integrity/ima/ima.h
@@ -133,6 +133,7 @@ void ima_print_digest(struct seq_file *m, u8 *digest, u32 size);
struct ima_template_desc *ima_template_desc_current(void);
int ima_restore_measurement_entry(struct ima_template_entry *entry);
int ima_restore_measurement_list(loff_t bufsize, void *buf);
+unsigned long ima_get_binary_runtime_size(void);
int ima_init_template(void);
#ifdef CONFIG_KEXEC_FILE
diff --git a/security/integrity/ima/ima_queue.c b/security/integrity/ima/ima_queue.c
index 12d1b04..3a3cc2a 100644
--- a/security/integrity/ima/ima_queue.c
+++ b/security/integrity/ima/ima_queue.c
@@ -29,6 +29,11 @@
#define AUDIT_CAUSE_LEN_MAX 32
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
/* key: inode (before secure-hashing a file) */
struct ima_h_table ima_htable = {
@@ -64,6 +69,24 @@ static struct ima_queue_entry *ima_lookup_digest_entry(u8 *digest_value,
return ret;
}
+/*
+ * Calculate the memory required for serializing a single
+ * binary_runtime_measurement list entry, which contains a
+ * couple of variable length fields (e.g template name and data).
+ */
+static int get_binary_runtime_size(struct ima_template_entry *entry)
+{
+ int size = 0;
+
+ size += sizeof(u32); /* pcr */
+ size += sizeof(entry->digest);
+ size += sizeof(int); /* template name size field */
+ size += strlen(entry->template_desc->name);
+ size += sizeof(entry->template_data_len);
+ size += entry->template_data_len;
+ return size;
+}
+
/* ima_add_template_entry helper function:
* - Add template entry to the measurement list and hash table, for
* all entries except those carried across kexec.
@@ -90,9 +113,30 @@ static int ima_add_digest_entry(struct ima_template_entry *entry, int flags)
key = ima_hash_key(entry->digest);
hlist_add_head_rcu(&qe->hnext, &ima_htable.queue[key]);
}
+
+ if (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;
+ }
return 0;
}
+/*
+ * Return the amount of memory required for serializing the
+ * entire binary_runtime_measurement list, including the ima_kexec_hdr
+ * structure.
+ */
+unsigned long ima_get_binary_runtime_size(void)
+{
+ if (binary_runtime_size >= (ULONG_MAX - sizeof(struct ima_kexec_hdr)))
+ return ULONG_MAX;
+ else
+ return binary_runtime_size + sizeof(struct ima_kexec_hdr);
+};
+
static int ima_pcr_extend(const u8 *hash, int pcr)
{
int result = 0;
@@ -106,8 +150,13 @@ static int ima_pcr_extend(const u8 *hash, int pcr)
return result;
}
-/* Add template entry to the measurement list and hash table,
- * and extend the pcr.
+/*
+ * Add template entry to the measurement list and hash table, and
+ * extend the pcr.
+ *
+ * On systems which support carrying the IMA measurement list across
+ * kexec, maintain the total memory size required for serializing the
+ * binary_runtime_measurements.
*/
int ima_add_template_entry(struct ima_template_entry *entry, int violation,
const char *op, struct inode *inode,
--
2.1.0
