On 2020-12-24 5:04 a.m., Mimi Zohar wrote:
On Sat, 2020-12-12 at 10:02 -0800, Tushar Sugandhi wrote:
IMA provides capabilities to measure file data, and in-memory buffer
No need for the comma here.
Up to this patch set, all the patches refer to "buffer data", not "in-
memory buffer data". This patch introduces the concept of measuring
"in-memory buffer data". Please remove "in-memory" above.
Will update the description accordingly.
data. However, various data structures, policies, and states
Here and everywhere else, there are two blanks after a period.
I checked this patch file in multiple text editors, but couldn’t find
any instance of period followed by two spaces. I will double check again
all the patches for multiple spaces, and remove them if any.
stored in kernel memory also impact the integrity of the system.
Several kernel subsystems contain such integrity critical data. These
kernel subsystems help protect the integrity of a device. Currently,
^integrity of the system.
Will do.
IMA does not provide a generic function for kernel subsystems to measure
their integrity critical data.
The emphasis should not be on "kernel subsystems". Simplify to "for
measuring kernel integrity critical data".
Will do.
Define a new IMA hook - ima_measure_critical_data to measure kernel
integrity critical data.
Either "ima_measure_critical_data" is between hyphens or without any
hyphens. If not hyphenated, then you could say "named
ima_measure_critical_data", but "named" isn't necessary. Or reverse "a
new IMA hook" and "ima_measure_critical_data", adding comma's like:
Define ima_measure_critical_data, a new IMA hook, to ...
Any of the above options work, just not a single hyphen.
Thanks for the suggestion.
I will use “Define ima_measure_critical_data, a new IMA hook, to ...”
Signed-off-by: Tushar Sugandhi <tusharsu@xxxxxxxxxxxxxxxxxxx>
Reviewed-by: Tyler Hicks <tyhicks@xxxxxxxxxxxxxxxxxxx>
---
<snip>
diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
index 0f8409d77602..dff4bce4fb09 100644
--- a/security/integrity/ima/ima_main.c
+++ b/security/integrity/ima/ima_main.c
@@ -922,6 +922,40 @@ void ima_kexec_cmdline(int kernel_fd, const void *buf, int size)
fdput(f);
}
+/**
+ * ima_measure_critical_data - measure kernel integrity critical data
+ * @event_name: event name to be used for the buffer entry
Why future tense?
I simply used the description from p_b_m()
* @eventname: event name to be used for the buffer entry.
By "buffer entry" do you mean a record in the IMA
measurement list?
Yes, a record in the IMA measurement list.
Will remove the future tense and reword it to something like:
* @event_name: event name for the buffer measurement entry
-or-
* @event_name: event name for the record in the IMA measurement list
+ * @buf: pointer to buffer containing data to measure
^pointer to buffer data
will do.
+ * @buf_len: length of buffer(in bytes)
^length of buffer data (in bytes)
will do.
+ * @measure_buf_hash: measure buffer hash
As requested in 2/8, please abbreviate the boolean name to "hash".
Refer to section "4) Naming" in Documentation/process/coding-style.rst
for variable naming conventions.
^@hash: measure buffer data hash
Sounds good. Will do.
+ *
+ * Measure the kernel subsystem data, critical to the integrity of the kernel,
+ * into the IMA log and extend the @pcr.
+ *
+ * Use @event_name to describe the state/buffer data change.
+ * Examples of critical data (@buf) could be various data structures,
+ * policies, and states stored in kernel memory that can impact the integrity
+ * of the system.
+ *
+ * If @measure_buf_hash is set to true - measure hash of the buffer data,
+ * else measure the buffer data itself.
+ * @measure_buf_hash can be used to save space, if the data being measured
+ * is too large.
+ *
+ * The data (@buf) can only be measured, not appraised.
The "/**" is the start of kernel-doc. Have you seen anywhere else in
My impression was the hooks in ima_main.c e.g. ima_file_free()
ima_file_mmap() required the double-asterisk ("/**"), and internal
functions like ima_rdwr_violation_check() require a single-asterisk
("/*")
kernel-doc.rst suggest the double-asterisk ("/**") for function comment
as well.
Function documentation
----------------------
The general format of a function and function-like macro kernel-doc
comment is::
/**
* function_name() - Brief description of function.
Please let me know if you still want me to remove the double-asterisk
("/**") here.
the kernel using the @<variable name> in the longer function
description? Have you seen this style of longer function
description? Refer to Documentation/doc-guide/kernel-doc.rst and other
code for examples.
Thanks. I will remove the prefix "@" from <variable name> in the longer
function description.
+ */
+void ima_measure_critical_data(const char *event_name,
+ const void *buf, int buf_len,
As "buf_len" should always be >= 0, it should not be defined as a
signed variable.
Good point. I will switch to either size_t or unsigned int.
+ bool measure_buf_hash)
+{
+ if (!event_name || !buf || !buf_len)
+ return;
+
+ process_buffer_measurement(NULL, buf, buf_len, event_name,
+ CRITICAL_DATA, 0, NULL,
+ measure_buf_hash);
^hash
Will do.
thanks,
Mimi
Thanks,
Tushar
+}
+
static int __init init_ima(void)
{
int error;
--
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