[PATCH] add rule filterkey
Add support for a rule key, which can be used to tie audit records to audit
rules. This is useful when a watched file is accessed through a link or
symlink, as well as for general audit log analysis.
Because this patch uses a string key instead of an integer key, there is a bit
of extra overhead to do the kstrdup() when a rule fires. However, we're also
allocating memory for the audit record buffer, so it's probably not that
significant. I went ahead with a string key because it seems more
user-friendly.
Note that the user must ensure that filterkeys are unique. The kernel only
checks for duplicate rules.
Signed-off-by: Amy Griffis <amy.griffis@hpd.com>
diff --git a/kernel/auditsc.c b/kernel/auditsc.c
index dc5e3f0..3166578 100644
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -186,6 +186,7 @@
int auditable; /* 1 if record should be written */
int name_count;
struct audit_names names[AUDIT_NAMES];
+ char * filterkey; /* key for rule that triggered record */
struct dentry * pwd;
struct vfsmount * pwdmnt;
struct audit_context *previous; /* For nested syscalls */
@@ -348,11 +349,17 @@
if (ctx)
result = audit_comparator(ctx->argv[f->type-AUDIT_ARG0], f->op, f->val);
break;
+ case AUDIT_FILTERKEY:
+ /* ignore this field for filtering */
+ result = 1;
+ break;
}
if (!result)
return 0;
}
+ if (rule->filterkey)
+ ctx->filterkey = kstrdup(rule->filterkey, GFP_ATOMIC);
switch (rule->action) {
case AUDIT_NEVER: *state = AUDIT_DISABLED; break;
case AUDIT_ALWAYS: *state = AUDIT_RECORD_CONTEXT; break;
@@ -627,6 +634,7 @@
}
audit_free_names(context);
audit_free_aux(context);
+ kfree(context->filterkey);
kfree(context);
context = previous;
} while (context);
@@ -735,6 +743,11 @@
context->euid, context->suid, context->fsuid,
context->egid, context->sgid, context->fsgid, tty);
audit_log_task_info(ab, tsk);
+ if (context->filterkey) {
+ audit_log_format(ab, " key=");
+ audit_log_untrustedstring(ab, context->filterkey);
+ } else
+ audit_log_format(ab, " key=(null)");
audit_log_end(ab);
for (aux = context->aux; aux; aux = aux->next) {
@@ -1060,6 +1073,8 @@
} else {
audit_free_names(context);
audit_free_aux(context);
+ kfree(context->filterkey);
+ context->filterkey = NULL;
tsk->audit_context = context;
}
}