Re: [PATCH v2 2/3] IMA: Add log statements for failure conditions.
From: Tushar Sugandhi
Date: Tue Feb 11 2020 - 14:14:10 EST
Hi Joe,
On 2020-02-10 7:23 p.m., Joe Perches wrote:
On Mon, 2020-02-10 at 18:47 -0800, Tushar Sugandhi wrote:
process_buffer_measurement() and ima_alloc_key_entry()
functions do not have log messages for failure conditions.
trivia:
diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
[]
@@ -757,6 +757,9 @@ void process_buffer_measurement(const void *buf, int size,
ima_free_template_entry(entry);
out:
+ if (ret < 0)
+ pr_err("Process buffer measurement failed, result: %d\n", ret);
perhaps use %s, __func__
pr_err("%s: failed, result: %d\n", __func__, ret);
Sounds good. Will make this change in the next update.
diff --git a/security/integrity/ima/ima_queue_keys.c b/security/integrity/ima/ima_queue_keys.c
[]
@@ -90,6 +90,7 @@ static struct ima_key_entry *ima_alloc_key_entry(struct key *keyring,
out:
if (rc) {
+ pr_err("Key entry allocation failed, result: %d\n", rc);
ima_free_key_entry(entry);
entry = NULL;
}
Likely the pr_err is unnecessary here as kmalloc, kstrdup
and kmemdup all emit a dump_stack() on allocation failure.
Thanks for pointing out kmalloc, kstrdup, and kmemdup emit a
dump_stack(). But keeping the above pr_err() will help associate the
failure with IMA.
For instance - "dmesg | grep ima:" will include this error.
Perhaps I should add __func__ here as well.
And since we are redefining the pr_fmt to prefix module and base names,
it will help further to pinpoint where exactly the failure is coming from.
Perhaps instead:
o Remove unnecessary indentation in ima_free_key_entry by
returning early on NULL argument
o Remove unnecessary rc, tests and label in ima_alloc_key_entry
---
security/integrity/ima/ima_queue_keys.c | 37 +++++++++++++--------------------
1 file changed, 15 insertions(+), 22 deletions(-)
diff --git a/security/integrity/ima/ima_queue_keys.c b/security/integrity/ima/ima_queue_keys.c
index c87c722..ba449f 100644
--- a/security/integrity/ima/ima_queue_keys.c
+++ b/security/integrity/ima/ima_queue_keys.c
@@ -58,42 +58,35 @@ void ima_init_key_queue(void)
static void ima_free_key_entry(struct ima_key_entry *entry)
{
- if (entry) {
- kfree(entry->payload);
- kfree(entry->keyring_name);
- kfree(entry);
- }
+ if (!entry)
+ return;
+
+ kfree(entry->payload);
+ kfree(entry->keyring_name);
+ kfree(entry);
}
Thanks for the feedback. Appreciate it. I would like to make this fix.
But I am not sure if this patchset, which mainly focuses on improving
logging in IMA, is the right patchset for this.
static struct ima_key_entry *ima_alloc_key_entry(struct key *keyring,
const void *payload,
size_t payload_len)
{
- int rc = 0;
struct ima_key_entry *entry;
entry = kzalloc(sizeof(*entry), GFP_KERNEL);
- if (entry) {
- entry->payload = kmemdup(payload, payload_len, GFP_KERNEL);
- entry->keyring_name = kstrdup(keyring->description,
- GFP_KERNEL);
- entry->payload_len = payload_len;
- }
-
- if ((entry == NULL) || (entry->payload == NULL) ||
- (entry->keyring_name == NULL)) {
- rc = -ENOMEM;
- goto out;
- }
+ if (!entry)
+ return NULL;
- INIT_LIST_HEAD(&entry->list);
+ entry->payload = kmemdup(payload, payload_len, GFP_KERNEL);
+ entry->payload_len = payload_len;
+ entry->keyring_name = kstrdup(keyring->description, GFP_KERNEL);
-out:
- if (rc) {
+ if (!entry->payload || !entry->keyring_name) {
ima_free_key_entry(entry);
- entry = NULL;
+ return NULL;
}
+ INIT_LIST_HEAD(&entry->list);
+
return entry;
}
Thanks again. This recommended change certainly makes the code more
readable. But again, I am not sure if this patchset is the right one for
this proposed change.
Perhaps I can create another patchset for the above two recommended
changes, and only focus on improving logging in this patchset?
Thanks,
Tushar