[PATCH v8 13/14] ima: Write modsig to the measurement list

From: Thiago Jung Bauermann
Date: Fri Nov 16 2018 - 15:09:33 EST


Add modsig support to the "sig" template field, allowing the the contents
of the modsig to be included in the measurement list.

Suggested-by: Mimi Zohar <zohar@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Thiago Jung Bauermann <bauerman@xxxxxxxxxxxxx>
---
security/integrity/ima/ima.h | 7 +++++++
security/integrity/ima/ima_modsig.c | 13 +++++++++++++
security/integrity/ima/ima_template_lib.c | 15 ++++++++++++++-
3 files changed, 34 insertions(+), 1 deletion(-)

diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h
index 7f88e4b86156..8e1b1ddbe14f 100644
--- a/security/integrity/ima/ima.h
+++ b/security/integrity/ima/ima.h
@@ -315,6 +315,7 @@ int ima_read_modsig(enum ima_hooks func, const void *buf, loff_t buf_len,
int *xattr_len);
int ima_get_modsig_hash(struct evm_ima_xattr_data *hdr, enum hash_algo *algo,
const u8 **hash, u8 *len);
+int ima_modsig_serialize_data(struct evm_ima_xattr_data **data, int *data_len);
int ima_modsig_verify(const unsigned int keyring_id,
struct evm_ima_xattr_data *hdr);
void ima_free_xattr_data(struct evm_ima_xattr_data *hdr);
@@ -339,6 +340,12 @@ static inline int ima_get_modsig_hash(struct evm_ima_xattr_data *hdr,
return -EOPNOTSUPP;
}

+static inline int ima_modsig_serialize_data(struct evm_ima_xattr_data **data,
+ int *data_len)
+{
+ return -EOPNOTSUPP;
+}
+
static inline int ima_modsig_verify(const unsigned int keyring_id,
struct evm_ima_xattr_data *hdr)
{
diff --git a/security/integrity/ima/ima_modsig.c b/security/integrity/ima/ima_modsig.c
index 584d9d77b2c4..e31ab7dc11db 100644
--- a/security/integrity/ima/ima_modsig.c
+++ b/security/integrity/ima/ima_modsig.c
@@ -167,6 +167,19 @@ int ima_get_modsig_hash(struct evm_ima_xattr_data *hdr, enum hash_algo *algo,
return pkcs7_get_digest(modsig->pkcs7_msg, hash, len);
}

+int ima_modsig_serialize_data(struct evm_ima_xattr_data **data, int *data_len)
+{
+ struct modsig_hdr *modsig = (struct modsig_hdr *) *data;
+
+ if (!*data || (*data)->type != IMA_MODSIG)
+ return -EINVAL;
+
+ *data = &modsig->raw_pkcs7;
+ *data_len = modsig->raw_pkcs7_len;
+
+ return 0;
+}
+
int ima_modsig_verify(const unsigned int keyring_id,
struct evm_ima_xattr_data *hdr)
{
diff --git a/security/integrity/ima/ima_template_lib.c b/security/integrity/ima/ima_template_lib.c
index 36d175816894..417cd153ba60 100644
--- a/security/integrity/ima/ima_template_lib.c
+++ b/security/integrity/ima/ima_template_lib.c
@@ -411,10 +411,23 @@ int ima_eventsig_init(struct ima_event_data *event_data,
struct ima_field_data *field_data)
{
struct evm_ima_xattr_data *xattr_value = event_data->xattr_value;
+ int xattr_len = event_data->xattr_len;

if (!is_signed(xattr_value))
return 0;

- return ima_write_template_field_data(xattr_value, event_data->xattr_len,
+ /*
+ * The xattr_value for IMA_MODSIG is a runtime structure containing
+ * pointers. Get its raw data instead.
+ */
+ if (xattr_value->type == IMA_MODSIG) {
+ int rc;
+
+ rc = ima_modsig_serialize_data(&xattr_value, &xattr_len);
+ if (rc)
+ return rc;
+ }
+
+ return ima_write_template_field_data(xattr_value, xattr_len,
DATA_FMT_HEX, field_data);
}