Skip to content

Commit

Permalink
audit: add fields to exclude filter by reusing user filter
Browse files Browse the repository at this point in the history 
RFE: add additional fields for use in audit filter exclude rules
https://github.com/linux-audit/audit-kernel/issues/5

Re-factor and combine audit_filter_type() with audit_filter_user() to
use audit_filter_user_rules() to enable the exclude filter to
additionally filter on PID, UID, GID, AUID, LOGINUID_SET, SUBJ_*.

The process of combining the similar audit_filter_user() and
audit_filter_type() functions, required inverting the meaning and
including the ALWAYS action of the latter.

Include audit_filter_user_rules() into audit_filter(), removing
unneeded logic in the process.

Keep the check to quit early if the list is empty.

Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
[PM: checkpatch.pl fixes - whitespace damage, wrapped description]
Signed-off-by: Paul Moore <paul@paul-moore.com>
  • Loading branch information
Richard Guy Briggs authored and Paul Moore committed Jun 27, 2016
1 parent da7f750 commit 86b2efb
Show file tree
Hide file tree
Showing 4 changed files with 57 additions and 102 deletions.
2 changes: 0 additions & 2 deletions include/linux/audit.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -163,8 +163,6 @@ extern void audit_log_task_info(struct audit_buffer *ab,
extern int audit_update_lsm_rules(void);

/* Private API (for audit.c only) */
extern int audit_filter_user(int type);
extern int audit_filter_type(int type);
extern int audit_rule_change(int type, __u32 portid, int seq,
void *data, size_t datasz);
extern int audit_list_rules_send(struct sk_buff *request_skb, int seq);
Expand Down
4 changes: 2 additions & 2 deletions kernel/audit.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -934,7 +934,7 @@ static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
if (!audit_enabled && msg_type != AUDIT_USER_AVC)
return 0;

err = audit_filter_user(msg_type);
err = audit_filter(msg_type, AUDIT_FILTER_USER);
if (err == 1) { /* match or error */
err = 0;
if (msg_type == AUDIT_USER_TTY) {
Expand Down Expand Up @@ -1382,7 +1382,7 @@ struct audit_buffer *audit_log_start(struct audit_context *ctx, gfp_t gfp_mask,
if (audit_initialized != AUDIT_INITIALIZED)
return NULL;

if (unlikely(audit_filter_type(type)))
if (unlikely(!audit_filter(type, AUDIT_FILTER_TYPE)))
return NULL;

if (gfp_mask & __GFP_DIRECT_RECLAIM) {
Expand Down
2 changes: 2 additions & 0 deletions kernel/audit.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -327,6 +327,8 @@ extern pid_t audit_sig_pid;
extern kuid_t audit_sig_uid;
extern u32 audit_sig_sid;

extern int audit_filter(int msgtype, unsigned int listtype);

#ifdef CONFIG_AUDITSYSCALL
extern int __audit_signal_info(int sig, struct task_struct *t);
static inline int audit_signal_info(int sig, struct task_struct *t)
Expand Down
151 changes: 53 additions & 98 deletions kernel/auditfilter.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -1290,117 +1290,72 @@ int audit_compare_dname_path(const char *dname, const char *path, int parentlen)
return strncmp(p, dname, dlen);
}

static int audit_filter_user_rules(struct audit_krule *rule, int type,
enum audit_state *state)
{
int i;

for (i = 0; i < rule->field_count; i++) {
struct audit_field *f = &rule->fields[i];
pid_t pid;
int result = 0;
u32 sid;

switch (f->type) {
case AUDIT_PID:
pid = task_pid_nr(current);
result = audit_comparator(pid, f->op, f->val);
break;
case AUDIT_UID:
result = audit_uid_comparator(current_uid(), f->op, f->uid);
break;
case AUDIT_GID:
result = audit_gid_comparator(current_gid(), f->op, f->gid);
break;
case AUDIT_LOGINUID:
result = audit_uid_comparator(audit_get_loginuid(current),
f->op, f->uid);
break;
case AUDIT_LOGINUID_SET:
result = audit_comparator(audit_loginuid_set(current),
f->op, f->val);
break;
case AUDIT_MSGTYPE:
result = audit_comparator(type, f->op, f->val);
break;
case AUDIT_SUBJ_USER:
case AUDIT_SUBJ_ROLE:
case AUDIT_SUBJ_TYPE:
case AUDIT_SUBJ_SEN:
case AUDIT_SUBJ_CLR:
if (f->lsm_rule) {
security_task_getsecid(current, &sid);
result = security_audit_rule_match(sid,
f->type,
f->op,
f->lsm_rule,
NULL);
}
break;
}

if (result <= 0)
return result;
}
switch (rule->action) {
case AUDIT_NEVER:
*state = AUDIT_DISABLED;
break;
case AUDIT_ALWAYS:
*state = AUDIT_RECORD_CONTEXT;
break;
}
return 1;
}

int audit_filter_user(int type)
{
enum audit_state state = AUDIT_DISABLED;
struct audit_entry *e;
int rc, ret;

ret = 1; /* Audit by default */

rcu_read_lock();
list_for_each_entry_rcu(e, &audit_filter_list[AUDIT_FILTER_USER], list) {
rc = audit_filter_user_rules(&e->rule, type, &state);
if (rc) {
if (rc > 0 && state == AUDIT_DISABLED)
ret = 0;
break;
}
}
rcu_read_unlock();

return ret;
}

int audit_filter_type(int type)
int audit_filter(int msgtype, unsigned int listtype)
{
struct audit_entry *e;
int result = 0;
int ret = 1; /* Audit by default */

rcu_read_lock();
if (list_empty(&audit_filter_list[AUDIT_FILTER_TYPE]))
if (list_empty(&audit_filter_list[listtype]))
goto unlock_and_return;
list_for_each_entry_rcu(e, &audit_filter_list[listtype], list) {
int i, result = 0;

list_for_each_entry_rcu(e, &audit_filter_list[AUDIT_FILTER_TYPE],
list) {
int i;
for (i = 0; i < e->rule.field_count; i++) {
struct audit_field *f = &e->rule.fields[i];
if (f->type == AUDIT_MSGTYPE) {
result = audit_comparator(type, f->op, f->val);
if (!result)
break;
pid_t pid;
u32 sid;

switch (f->type) {
case AUDIT_PID:
pid = task_pid_nr(current);
result = audit_comparator(pid, f->op, f->val);
break;
case AUDIT_UID:
result = audit_uid_comparator(current_uid(), f->op, f->uid);
break;
case AUDIT_GID:
result = audit_gid_comparator(current_gid(), f->op, f->gid);
break;
case AUDIT_LOGINUID:
result = audit_uid_comparator(audit_get_loginuid(current),
f->op, f->uid);
break;
case AUDIT_LOGINUID_SET:
result = audit_comparator(audit_loginuid_set(current),
f->op, f->val);
break;
case AUDIT_MSGTYPE:
result = audit_comparator(msgtype, f->op, f->val);
break;
case AUDIT_SUBJ_USER:
case AUDIT_SUBJ_ROLE:
case AUDIT_SUBJ_TYPE:
case AUDIT_SUBJ_SEN:
case AUDIT_SUBJ_CLR:
if (f->lsm_rule) {
security_task_getsecid(current, &sid);
result = security_audit_rule_match(sid,
f->type, f->op, f->lsm_rule, NULL);
}
break;
default:
goto unlock_and_return;
}
if (result < 0) /* error */
goto unlock_and_return;
if (!result)
break;
}
if (result > 0) {
if (e->rule.action == AUDIT_NEVER || listtype == AUDIT_FILTER_TYPE)
ret = 0;
break;
}
if (result)
goto unlock_and_return;
}
unlock_and_return:
rcu_read_unlock();
return result;
return ret;
}

static int update_lsm_rule(struct audit_krule *r)
Expand Down

0 comments on commit 86b2efb

Please sign in to comment.