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Subject[PATCH v3] ima: drop vla in ima_audit_measurement()
Date
In keeping with the directive to get rid of VLAs [1], let's drop the VLA
from ima_audit_measurement(). We need to adjust the return type of
ima_audit_measurement, because now this function can fail if an allocation
fails.

[1]: https://lkml.org/lkml/2018/3/7/621

v2: just use audit_log_format instead of doing a second allocation
v3: ignore failures in ima_audit_measurement()

Signed-off-by: Tycho Andersen <tycho@tycho.ws>
---
security/integrity/ima/ima_api.c | 16 ++++++++++------
1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/security/integrity/ima/ima_api.c b/security/integrity/ima/ima_api.c
index 08fe405338e1..2aab9170ef68 100644
--- a/security/integrity/ima/ima_api.c
+++ b/security/integrity/ima/ima_api.c
@@ -308,14 +308,17 @@ void ima_audit_measurement(struct integrity_iint_cache *iint,
const unsigned char *filename)
{
struct audit_buffer *ab;
- char hash[(iint->ima_hash->length * 2) + 1];
+ char *hash;
const char *algo_name = hash_algo_name[iint->ima_hash->algo];
- char algo_hash[sizeof(hash) + strlen(algo_name) + 2];
int i;

if (iint->flags & IMA_AUDITED)
return;

+ hash = kzalloc((iint->ima_hash->length * 2) + 1, GFP_KERNEL);
+ if (!hash)
+ return;
+
for (i = 0; i < iint->ima_hash->length; i++)
hex_byte_pack(hash + (i * 2), iint->ima_hash->digest[i]);
hash[i * 2] = '\0';
@@ -323,18 +326,19 @@ void ima_audit_measurement(struct integrity_iint_cache *iint,
ab = audit_log_start(current->audit_context, GFP_KERNEL,
AUDIT_INTEGRITY_RULE);
if (!ab)
- return;
+ goto out;

audit_log_format(ab, "file=");
audit_log_untrustedstring(ab, filename);
- audit_log_format(ab, " hash=");
- snprintf(algo_hash, sizeof(algo_hash), "%s:%s", algo_name, hash);
- audit_log_untrustedstring(ab, algo_hash);
+ audit_log_format(ab, " hash=\"%s:%s\"", algo_name, hash);

audit_log_task_info(ab, current);
audit_log_end(ab);

iint->flags |= IMA_AUDITED;
+out:
+ kfree(hash);
+ return;
}

/*
--
2.14.1
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