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Subject[PATCH v3 2/3] ima: Return int in the functions to measure a buffer
Date
ima_measure_critical_data() and process_buffer_measurement() currently
don't return a result. A caller wouldn't be able to know whether those
functions were executed successfully.

This patch modifies the return type from void to int, and returns 0 if the
buffer has been successfully measured, a negative value otherwise.

Also, this patch does not modify the behavior of existing callers by
processing the returned value. For those, the return value is ignored.

Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
---
include/linux/ima.h | 15 +++++++-----
security/integrity/ima/ima.h | 10 ++++----
security/integrity/ima/ima_main.c | 40 ++++++++++++++++++-------------
3 files changed, 37 insertions(+), 28 deletions(-)

diff --git a/include/linux/ima.h b/include/linux/ima.h
index 81e830d01ced..60492263aa64 100644
--- a/include/linux/ima.h
+++ b/include/linux/ima.h
@@ -35,10 +35,10 @@ extern void ima_post_path_mknod(struct user_namespace *mnt_userns,
extern int ima_file_hash(struct file *file, char *buf, size_t buf_size);
extern int ima_inode_hash(struct inode *inode, char *buf, size_t buf_size);
extern void ima_kexec_cmdline(int kernel_fd, const void *buf, int size);
-extern void ima_measure_critical_data(const char *event_label,
- const char *event_name,
- const void *buf, size_t buf_len,
- bool hash);
+extern int ima_measure_critical_data(const char *event_label,
+ const char *event_name,
+ const void *buf, size_t buf_len,
+ bool hash);

#ifdef CONFIG_IMA_APPRAISE_BOOTPARAM
extern void ima_appraise_parse_cmdline(void);
@@ -144,10 +144,13 @@ static inline int ima_inode_hash(struct inode *inode, char *buf, size_t buf_size

static inline void ima_kexec_cmdline(int kernel_fd, const void *buf, int size) {}

-static inline void ima_measure_critical_data(const char *event_label,
+static inline int ima_measure_critical_data(const char *event_label,
const char *event_name,
const void *buf, size_t buf_len,
- bool hash) {}
+ bool hash)
+{
+ return -ENOENT;
+}

#endif /* CONFIG_IMA */

diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h
index f0e448ed1f9f..03db221324c3 100644
--- a/security/integrity/ima/ima.h
+++ b/security/integrity/ima/ima.h
@@ -264,11 +264,11 @@ void ima_store_measurement(struct integrity_iint_cache *iint, struct file *file,
struct evm_ima_xattr_data *xattr_value,
int xattr_len, const struct modsig *modsig, int pcr,
struct ima_template_desc *template_desc);
-void process_buffer_measurement(struct user_namespace *mnt_userns,
- struct inode *inode, const void *buf, int size,
- const char *eventname, enum ima_hooks func,
- int pcr, const char *func_data,
- bool buf_hash);
+int process_buffer_measurement(struct user_namespace *mnt_userns,
+ struct inode *inode, const void *buf, int size,
+ const char *eventname, enum ima_hooks func,
+ int pcr, const char *func_data,
+ bool buf_hash);
void ima_audit_measurement(struct integrity_iint_cache *iint,
const unsigned char *filename);
int ima_alloc_init_template(struct ima_event_data *event_data,
diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
index 8ef1fa357e0c..b512c06d8ee1 100644
--- a/security/integrity/ima/ima_main.c
+++ b/security/integrity/ima/ima_main.c
@@ -827,7 +827,7 @@ int ima_post_load_data(char *buf, loff_t size,
return 0;
}

-/*
+/**
* process_buffer_measurement - Measure the buffer or the buffer data hash
* @mnt_userns: user namespace of the mount the inode was found from
* @inode: inode associated with the object being measured (NULL for KEY_CHECK)
@@ -840,12 +840,15 @@ int ima_post_load_data(char *buf, loff_t size,
* @buf_hash: measure buffer data hash
*
* Based on policy, either the buffer data or buffer data hash is measured
+ *
+ * Return: 0 if the buffer has been successfully measured, a negative value
+ * otherwise.
*/
-void process_buffer_measurement(struct user_namespace *mnt_userns,
- struct inode *inode, const void *buf, int size,
- const char *eventname, enum ima_hooks func,
- int pcr, const char *func_data,
- bool buf_hash)
+int process_buffer_measurement(struct user_namespace *mnt_userns,
+ struct inode *inode, const void *buf, int size,
+ const char *eventname, enum ima_hooks func,
+ int pcr, const char *func_data,
+ bool buf_hash)
{
int ret = 0;
const char *audit_cause = "ENOMEM";
@@ -867,7 +870,7 @@ void process_buffer_measurement(struct user_namespace *mnt_userns,
u32 secid;

if (!ima_policy_flag)
- return;
+ return -ENOENT;

template = ima_template_desc_buf();
if (!template) {
@@ -889,7 +892,7 @@ void process_buffer_measurement(struct user_namespace *mnt_userns,
secid, 0, func, &pcr, &template,
func_data);
if (!(action & IMA_MEASURE))
- return;
+ return -ENOENT;
}

if (!pcr)
@@ -937,7 +940,7 @@ void process_buffer_measurement(struct user_namespace *mnt_userns,
func_measure_str(func),
audit_cause, ret, 0, ret);

- return;
+ return ret;
}

/**
@@ -977,18 +980,21 @@ void ima_kexec_cmdline(int kernel_fd, const void *buf, int size)
* and extend the pcr. Examples of critical data could be various data
* structures, policies, and states stored in kernel memory that can
* impact the integrity of the system.
+ *
+ * Return: 0 if the buffer has been successfully measured, a negative value
+ * otherwise.
*/
-void ima_measure_critical_data(const char *event_label,
- const char *event_name,
- const void *buf, size_t buf_len,
- bool hash)
+int ima_measure_critical_data(const char *event_label,
+ const char *event_name,
+ const void *buf, size_t buf_len,
+ bool hash)
{
if (!event_name || !event_label || !buf || !buf_len)
- return;
+ return -ENOPARAM;

- process_buffer_measurement(&init_user_ns, NULL, buf, buf_len, event_name,
- CRITICAL_DATA, 0, event_label,
- hash);
+ return process_buffer_measurement(&init_user_ns, NULL, buf, buf_len,
+ event_name, CRITICAL_DATA, 0,
+ event_label, hash);
}

static int __init init_ima(void)
--
2.25.1
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