audit: allow checking the type of audit message in the user filter

When userspace sends messages to the audit system it includes a type.
We want to be able to filter messages based on that type without have to
do the all or nothing option currently available on the
AUDIT_FILTER_TYPE filter list.  Instead we should be able to use the
AUDIT_FILTER_USER filter list and just use the message type as one part
of the matching decision.

Signed-off-by: Eric Paris <eparis@redhat.com>

diff --git a/include/linux/audit.h b/include/linux/audit.h
index 8f92e1d..b26d7f1 100644 (file)
--- a/include/linux/audit.h
+++ b/include/linux/audit.h
@@ -438,7 +438,7 @@ static inline void      audit_log_secctx(struct audit_buffer *ab, u32 secid)
 extern int                 audit_update_lsm_rules(void);
 
                                /* Private API (for audit.c only) */
-extern int audit_filter_user(void);
+extern int audit_filter_user(int type);
 extern int audit_filter_type(int type);
 extern int  audit_receive_filter(int type, int pid, int seq,
                                void *data, size_t datasz, kuid_t loginuid,

diff --git a/kernel/audit.c b/kernel/audit.c
index c45e6d2..1322714 100644 (file)
--- a/kernel/audit.c
+++ b/kernel/audit.c
@@ -737,7 +737,7 @@ 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();
+               err = audit_filter_user(msg_type);
                if (err == 1) {
                        err = 0;
                        if (msg_type == AUDIT_USER_TTY) {

diff --git a/kernel/auditfilter.c b/kernel/auditfilter.c
index f9fc54b..9e66600 100644 (file)
--- a/kernel/auditfilter.c
+++ b/kernel/auditfilter.c
@@ -310,6 +310,18 @@ static u32 audit_to_op(u32 op)
        return n;
 }
 
+/* check if a field is valid for a given list */
+static int audit_field_valid(struct audit_entry *entry, struct audit_field *f)
+{
+       switch(f->type) {
+       case AUDIT_MSGTYPE:
+               if (entry->rule.listnr != AUDIT_FILTER_TYPE &&
+                   entry->rule.listnr != AUDIT_FILTER_USER)
+                       return -EINVAL;
+               break;
+       };
+       return 0;
+}
 
 /* Translate struct audit_rule to kernel's rule respresentation.
  * Exists for backward compatibility with userspace. */
@@ -459,6 +471,13 @@ static struct audit_entry *audit_data_to_entry(struct audit_rule_data *data,
                f->gid = INVALID_GID;
                f->lsm_str = NULL;
                f->lsm_rule = NULL;
+
+               err = audit_field_valid(entry, f);
+               if (err)
+                       goto exit_free;
+
+               err = -EINVAL;
+
                switch(f->type) {
                case AUDIT_UID:
                case AUDIT_EUID:
@@ -1354,7 +1373,7 @@ 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,
+static int audit_filter_user_rules(struct audit_krule *rule, int type,
                                   enum audit_state *state)
 {
        int i;
@@ -1378,6 +1397,9 @@ static int audit_filter_user_rules(struct audit_krule *rule,
                        result = audit_uid_comparator(audit_get_loginuid(current),
                                                  f->op, f->uid);
                        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:
@@ -1404,7 +1426,7 @@ static int audit_filter_user_rules(struct audit_krule *rule,
        return 1;
 }
 
-int audit_filter_user(void)
+int audit_filter_user(int type)
 {
        enum audit_state state = AUDIT_DISABLED;
        struct audit_entry *e;
@@ -1412,7 +1434,7 @@ int audit_filter_user(void)
 
        rcu_read_lock();
        list_for_each_entry_rcu(e, &audit_filter_list[AUDIT_FILTER_USER], list) {
-               if (audit_filter_user_rules(&e->rule, &state)) {
+               if (audit_filter_user_rules(&e->rule, type, &state)) {
                        if (state == AUDIT_DISABLED)
                                ret = 0;
                        break;