[PATCH] audit=0 appears not to completely disable auditing

Steve Grubb
2007-03-09T20:50:15Z

Hi,

There was a bz, 231371, reporting that current upstream kernels do not completely
disable auditing when boot with audit=0 and the audit daemon not configured to
run. You can reproduce the problem by:

service auditd stop
auditctl -e 0
auditctl -w /etc/passwd
and you'd get an event in syslog:
Mar 9 15:43:04 localhost kernel: audit(1173472984.321:982): auid=4294967295
subj=user_u:system_r:auditctl_t:s0 op=add rule key=(null) list=4 res=1

The patch below solves this problem by checking audit_enabled before creating
an audit event.

Signed-off-by: Steve Grubb <sgrubb@redhat.com>

diff -urp linux-2.6.18.x86_64.orig/kernel/audit.c linux-2.6.18.x86_64/kernel/audit.c
--- linux-2.6.18.x86_64.orig/kernel/audit.c 2007-03-09 14:08:18.000000000 -0500
+++ linux-2.6.18.x86_64/kernel/audit.c 2007-03-09 14:06:59.000000000 -0500
@@ -238,46 +238,50 @@ void audit_log_lost(const char *message)

static int audit_set_rate_limit(int limit, uid_t loginuid, u32 sid)
{
- int old = audit_rate_limit;
+ if (audit_enabled) {
+ int old = audit_rate_limit;

- if (sid) {
- char *ctx = NULL;
- u32 len;
- int rc;
- if ((rc = selinux_ctxid_to_string(sid, &ctx, &len)))
- return rc;
- else
- audit_log(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE,
+ if (sid) {
+ char *ctx = NULL;
+ u32 len;
+ int rc;
+ if ((rc = selinux_ctxid_to_string(sid, &ctx, &len)))
+ return rc;
+ else
+ audit_log(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE,
"audit_rate_limit=%d old=%d by auid=%u subj=%s",
- limit, old, loginuid, ctx);
- kfree(ctx);
- } else
- audit_log(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE,
- "audit_rate_limit=%d old=%d by auid=%u",
- limit, old, loginuid);
+ limit, old, loginuid, ctx);
+ kfree(ctx);
+ } else
+ audit_log(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE,
+ "audit_rate_limit=%d old=%d by auid=%u",
+ limit, old, loginuid);
+ }
audit_rate_limit = limit;
return 0;
}

static int audit_set_backlog_limit(int limit, uid_t loginuid, u32 sid)
{
- int old = audit_backlog_limit;
+ if (audit_enabled) {
+ int old = audit_backlog_limit;

- if (sid) {
- char *ctx = NULL;
- u32 len;
- int rc;
- if ((rc = selinux_ctxid_to_string(sid, &ctx, &len)))
- return rc;
- else
- audit_log(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE,
+ if (sid) {
+ char *ctx = NULL;
+ u32 len;
+ int rc;
+ if ((rc = selinux_ctxid_to_string(sid, &ctx, &len)))
+ return rc;
+ else
+ audit_log(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE,
"audit_backlog_limit=%d old=%d by auid=%u subj=%s",
- limit, old, loginuid, ctx);
- kfree(ctx);
- } else
- audit_log(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE,
- "audit_backlog_limit=%d old=%d by auid=%u",
- limit, old, loginuid);
+ limit, old, loginuid, ctx);
+ kfree(ctx);
+ } else
+ audit_log(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE,
+ "audit_backlog_limit=%d old=%d by auid=%u",
+ limit, old, loginuid);
+ }
audit_backlog_limit = limit;
return 0;
}
@@ -289,21 +293,23 @@ static int audit_set_enabled(int state,
if (state != 0 && state != 1)
return -EINVAL;

- if (sid) {
- char *ctx = NULL;
- u32 len;
- int rc;
- if ((rc = selinux_ctxid_to_string(sid, &ctx, &len)))
- return rc;
- else
- audit_log(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE,
+ if (audit_enabled || state) {
+ if (sid) {
+ char *ctx = NULL;
+ u32 len;
+ int rc;
+ if ((rc = selinux_ctxid_to_string(sid, &ctx, &len)))
+ return rc;
+ else
+ audit_log(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE,
"audit_enabled=%d old=%d by auid=%u subj=%s",
- state, old, loginuid, ctx);
- kfree(ctx);
- } else
- audit_log(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE,
- "audit_enabled=%d old=%d by auid=%u",
- state, old, loginuid);
+ state, old, loginuid, ctx);
+ kfree(ctx);
+ } else
+ audit_log(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE,
+ "audit_enabled=%d old=%d by auid=%u",
+ state, old, loginuid);
+ }
audit_enabled = state;
return 0;
}
@@ -317,21 +323,23 @@ static int audit_set_failure(int state,
&& state != AUDIT_FAIL_PANIC)
return -EINVAL;

- if (sid) {
- char *ctx = NULL;
- u32 len;
- int rc;
- if ((rc = selinux_ctxid_to_string(sid, &ctx, &len)))
- return rc;
- else
- audit_log(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE,
+ if (audit_enabled) {
+ if (sid) {
+ char *ctx = NULL;
+ u32 len;
+ int rc;
+ if ((rc = selinux_ctxid_to_string(sid, &ctx, &len)))
+ return rc;
+ else
+ audit_log(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE,
"audit_failure=%d old=%d by auid=%u subj=%s",
- state, old, loginuid, ctx);
- kfree(ctx);
- } else
- audit_log(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE,
- "audit_failure=%d old=%d by auid=%u",
- state, old, loginuid);
+ state, old, loginuid, ctx);
+ kfree(ctx);
+ } else
+ audit_log(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE,
+ "audit_failure=%d old=%d by auid=%u",
+ state, old, loginuid);
+ }
audit_failure = state;
return 0;
}
@@ -536,22 +544,26 @@ static int audit_receive_msg(struct sk_b
if (err < 0) return err;
}
if (status_get->mask & AUDIT_STATUS_PID) {
- int old = audit_pid;
- if (sid) {
- if ((err = selinux_ctxid_to_string(
- sid, &ctx, &len)))
- return err;
- else
+ if (audit_enabled) {
+ int old = audit_pid;
+ if (sid) {
+ if ((err = selinux_ctxid_to_string(
+ sid, &ctx, &len)))
+ return err;
+ else
+ audit_log(NULL, GFP_KERNEL,
+ AUDIT_CONFIG_CHANGE,
+ "audit_pid=%d old=%d by auid=%u subj=%s",
+ status_get->pid, old,
+ loginuid, ctx);
+ kfree(ctx);
+ } else
audit_log(NULL, GFP_KERNEL,
AUDIT_CONFIG_CHANGE,
- "audit_pid=%d old=%d by auid=%u subj=%s",
- status_get->pid, old,
- loginuid, ctx);
- kfree(ctx);
- } else
- audit_log(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE,
"audit_pid=%d old=%d by auid=%u",
- status_get->pid, old, loginuid);
+ status_get->pid, old,
+ loginuid);
+ }
audit_pid = status_get->pid;
}
if (status_get->mask & AUDIT_STATUS_RATE_LIMIT)
diff -urp linux-2.6.18.x86_64.orig/kernel/auditfilter.c linux-2.6.18.x86_64/kernel/auditfilter.c
--- linux-2.6.18.x86_64.orig/kernel/auditfilter.c 2007-03-09 14:08:18.000000000 -0500
+++ linux-2.6.18.x86_64/kernel/auditfilter.c 2007-03-09 14:05:54.000000000 -0500
@@ -95,6 +95,8 @@ extern struct inotify_handle *audit_ih;
/* Inotify events we care about. */
#define AUDIT_IN_WATCH IN_MOVE|IN_CREATE|IN_DELETE|IN_DELETE_SELF|IN_MOVE_SELF

+extern int audit_enabled;
+
void audit_free_parent(struct inotify_watch *i_watch)
{
struct audit_parent *parent;
@@ -897,7 +899,6 @@ static void audit_update_watch(struct au
struct audit_watch *owatch, *nwatch, *nextw;
struct audit_krule *r, *nextr;
struct audit_entry *oentry, *nentry;
- struct audit_buffer *ab;

mutex_lock(&audit_filter_mutex);
list_for_each_entry_safe(owatch, nextw, &parent->watches, wlist) {
@@ -937,13 +938,18 @@ static void audit_update_watch(struct au
call_rcu(&oentry->rcu, audit_free_rule_rcu);
}

- ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE);
- audit_log_format(ab, "op=updated rules specifying path=");
- audit_log_untrustedstring(ab, owatch->path);
- audit_log_format(ab, " with dev=%u ino=%lu\n", dev, ino);
- audit_log_format(ab, " list=%d res=1", r->listnr);
- audit_log_end(ab);
-
+ if (audit_enabled) {
+ struct audit_buffer *ab;
+ ab = audit_log_start(NULL, GFP_KERNEL,
+ AUDIT_CONFIG_CHANGE);
+ audit_log_format(ab,
+ "op=updated rules specifying path=");
+ audit_log_untrustedstring(ab, owatch->path);
+ audit_log_format(ab, " with dev=%u ino=%lu\n",
+ dev, ino);
+ audit_log_format(ab, " list=%d res=1", r->listnr);
+ audit_log_end(ab);
+ }
audit_remove_watch(owatch);
goto add_watch_to_parent; /* event applies to a single watch */
}
@@ -962,25 +968,28 @@ static void audit_remove_parent_watches(
struct audit_watch *w, *nextw;
struct audit_krule *r, *nextr;
struct audit_entry *e;
- struct audit_buffer *ab;

mutex_lock(&audit_filter_mutex);
parent->flags |= AUDIT_PARENT_INVALID;
list_for_each_entry_safe(w, nextw, &parent->watches, wlist) {
list_for_each_entry_safe(r, nextr, &w->rules, rlist) {
e = container_of(r, struct audit_entry, rule);
-
- ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE);
- audit_log_format(ab, "op=remove rule path=");
- audit_log_untrustedstring(ab, w->path);
- if (r->filterkey) {
- audit_log_format(ab, " key=");
- audit_log_untrustedstring(ab, r->filterkey);
- } else
- audit_log_format(ab, " key=(null)");
- audit_log_format(ab, " list=%d res=1", r->listnr);
- audit_log_end(ab);
-
+ if (audit_enabled) {
+ struct audit_buffer *ab;
+ ab = audit_log_start(NULL, GFP_KERNEL,
+ AUDIT_CONFIG_CHANGE);
+ audit_log_format(ab, "op=remove rule path=");
+ audit_log_untrustedstring(ab, w->path);
+ if (r->filterkey) {
+ audit_log_format(ab, " key=");
+ audit_log_untrustedstring(ab,
+ r->filterkey);
+ } else
+ audit_log_format(ab, " key=(null)");
+ audit_log_format(ab, " list=%d res=1",
+ r->listnr);
+ audit_log_end(ab);
+ }
list_del(&r->rlist);
list_del_rcu(&e->list);
call_rcu(&e->rcu, audit_free_rule_rcu);
@@ -1409,6 +1418,9 @@ static void audit_log_rule_change(uid_t
{
struct audit_buffer *ab;

+ if (!audit_enabled)
+ return;
+
ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE);
if (!ab)
return;