ima: drop vla in ima_audit_measurement()

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>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>

diff --git a/security/integrity/ima/ima_api.c b/security/integrity/ima/ima_api.c
index 33b4458cdbef748b4e0cdbb400b8ab43b51b6b8d..bf88236b7a0bfbb30b550b7e31c35ea1c0ebbaa3 100644 (file)
--- a/security/integrity/ima/ima_api.c
+++ b/security/integrity/ima/ima_api.c
@@ -311,14 +311,17 @@ 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';
@@ -326,18 +329,19 @@ 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;
 }
 
 /*