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Date: Mon, 7 Feb 2022 20:41:34 -0500
From: Mimi Zohar <zohar@...ux.ibm.com>
To: linux-integrity@...r.kernel.org
Cc: Mimi Zohar <zohar@...ux.ibm.com>,
Eric Biggers <ebiggers@...nel.org>,
Stefan Berger <stefanb@...ux.ibm.com>,
linux-fscrypt@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH v4 2/8] ima: define ima_max_digest_data struct without a flexible array variable
To support larger hash digests in the 'iint' cache, instead of defining
the 'digest' field as the maximum digest size, the 'digest' field was
defined as a flexible array variable and was dynamically allocated.
This resulted in wrapping the "ima_digest_data" struct inside a local
structure with the maximum digest size in a number of places.
The original reason for defining the 'digest' field as a flexible array
variable is still valid for the 'iint' cache use case. In addition,
define 'ima_max_digest_data' struct to be use instead of the (ugly)
local wrapping of the "ima_digest_data" struct.
Signed-off-by: Mimi Zohar <zohar@...ux.ibm.com>
---
security/integrity/ima/ima_api.c | 20 ++++++++++----------
security/integrity/ima/ima_init.c | 10 ++++------
security/integrity/integrity.h | 24 ++++++++++++++++++++++++
3 files changed, 38 insertions(+), 16 deletions(-)
diff --git a/security/integrity/ima/ima_api.c b/security/integrity/ima/ima_api.c
index 5b220a2fe573..45294f18dabc 100644
--- a/security/integrity/ima/ima_api.c
+++ b/security/integrity/ima/ima_api.c
@@ -217,14 +217,11 @@ int ima_collect_measurement(struct integrity_iint_cache *iint,
const char *audit_cause = "failed";
struct inode *inode = file_inode(file);
const char *filename = file->f_path.dentry->d_name.name;
+ struct ima_max_digest_data hash;
int result = 0;
int length;
void *tmpbuf;
u64 i_version;
- struct {
- struct ima_digest_data hdr;
- char digest[IMA_MAX_DIGEST_SIZE];
- } hash;
/*
* Always collect the modsig, because IMA might have already collected
@@ -239,24 +236,27 @@ int ima_collect_measurement(struct integrity_iint_cache *iint,
/*
* Detecting file change is based on i_version. On filesystems
- * which do not support i_version, support is limited to an initial
- * measurement/appraisal/audit.
+ * which do not support i_version, support was originally limited
+ * to an initial measurement/appraisal/audit, but was modified to
+ * assume the file changed.
*/
i_version = inode_query_iversion(inode);
- hash.hdr.algo = algo;
+ hash.algo = algo;
/* Initialize hash digest to 0's in case of failure */
memset(&hash.digest, 0, sizeof(hash.digest));
if (buf)
- result = ima_calc_buffer_hash(buf, size, &hash.hdr);
+ result = ima_calc_buffer_hash(buf, size,
+ (struct ima_digest_data *)&hash);
else
- result = ima_calc_file_hash(file, &hash.hdr);
+ result = ima_calc_file_hash(file,
+ (struct ima_digest_data *)&hash);
if (result && result != -EBADF && result != -EINVAL)
goto out;
- length = sizeof(hash.hdr) + hash.hdr.length;
+ length = sizeof(struct ima_digest_data) + hash.length;
tmpbuf = krealloc(iint->ima_hash, length, GFP_NOFS);
if (!tmpbuf) {
result = -ENOMEM;
diff --git a/security/integrity/ima/ima_init.c b/security/integrity/ima/ima_init.c
index b26fa67476b4..890821af08dd 100644
--- a/security/integrity/ima/ima_init.c
+++ b/security/integrity/ima/ima_init.c
@@ -47,16 +47,13 @@ static int __init ima_add_boot_aggregate(void)
struct integrity_iint_cache tmp_iint, *iint = &tmp_iint;
struct ima_event_data event_data = { .iint = iint,
.filename = boot_aggregate_name };
+ struct ima_max_digest_data hash;
int result = -ENOMEM;
int violation = 0;
- struct {
- struct ima_digest_data hdr;
- char digest[TPM_MAX_DIGEST_SIZE];
- } hash;
memset(iint, 0, sizeof(*iint));
memset(&hash, 0, sizeof(hash));
- iint->ima_hash = &hash.hdr;
+ iint->ima_hash = (struct ima_digest_data *)&hash;
iint->ima_hash->algo = ima_hash_algo;
iint->ima_hash->length = hash_digest_size[ima_hash_algo];
@@ -73,7 +70,8 @@ static int __init ima_add_boot_aggregate(void)
* is not found.
*/
if (ima_tpm_chip) {
- result = ima_calc_boot_aggregate(&hash.hdr);
+ result = ima_calc_boot_aggregate((struct ima_digest_data *)
+ &hash);
if (result < 0) {
audit_cause = "hashing_error";
goto err_out;
diff --git a/security/integrity/integrity.h b/security/integrity/integrity.h
index d045dccd415a..ee2e6b7c7575 100644
--- a/security/integrity/integrity.h
+++ b/security/integrity/integrity.h
@@ -15,6 +15,7 @@
#include <linux/types.h>
#include <linux/integrity.h>
#include <crypto/sha1.h>
+#include <crypto/hash.h>
#include <linux/key.h>
#include <linux/audit.h>
@@ -110,6 +111,29 @@ struct ima_digest_data {
u8 digest[];
} __packed;
+/*
+ * Instead of dynamically allocating memory for the ima_digest_data struct
+ * with space for the specific hash algo or wrapping the ima_digest_data
+ * struct inside another local structure, define ima_max_digest_data struct
+ * with the maximum digest size.
+ */
+struct ima_max_digest_data {
+ u8 algo;
+ u8 length;
+ union {
+ struct {
+ u8 unused;
+ u8 type;
+ } sha1;
+ struct {
+ u8 type;
+ u8 algo;
+ } ng;
+ u8 data[2];
+ } xattr;
+ u8 digest[HASH_MAX_DIGESTSIZE];
+} __packed;
+
/*
* signature format v2 - for using with asymmetric keys
*/
--
2.27.0
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