audit: Use current instead of NETLINK_CREDS() in audit_filter

Get caller process uid and gid and pid values from the current task
instead of the NETLINK_CB.  This is simpler than passing NETLINK_CREDS
from from audit_receive_msg to audit_filter_user_rules and avoid the
chance of being hit by the occassional bugs in netlink uid/gid
credential passing.  This is a safe changes because all netlink
requests are processed in the task of the sending process.

Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Eric Paris <eparis@redhat.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>

2 files changed, 7 insertions, 8 deletions

diff --git a/kernel/audit.c b/kernel/audit.c
index 7b7268e3073b..fecb1507b485 100644
--- a/kernel/audit.c
+++ b/kernel/audit.c
@@ -744,7 +744,7 @@ 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(&NETLINK_CB(skb));
+                err = audit_filter_user();
                 if (err == 1) {
                         err = 0;
                         if (msg_type == AUDIT_USER_TTY) {
diff --git a/kernel/auditfilter.c b/kernel/auditfilter.c
index a6c3f1abd206..b754f43bc56c 100644
--- a/kernel/auditfilter.c
+++ b/kernel/auditfilter.c
@@ -1236,8 +1236,7 @@ int audit_compare_dname_path(const char *dname, const char *path,
         return strncmp(p, dname, dlen);
 }
 
-static int audit_filter_user_rules(struct netlink_skb_parms *cb,
-                                   struct audit_krule *rule,
+static int audit_filter_user_rules(struct audit_krule *rule,
                                    enum audit_state *state)
 {
         int i;
@@ -1249,13 +1248,13 @@ static int audit_filter_user_rules(struct netlink_skb_parms *cb,
 
                 switch (f->type) {
                 case AUDIT_PID:
-                        result = audit_comparator(cb->creds.pid, f->op, f->val);
+                        result = audit_comparator(task_pid_vnr(current), f->op, f->val);
                         break;
                 case AUDIT_UID:
-                        result = audit_comparator(cb->creds.uid, f->op, f->val);
+                        result = audit_comparator(current_uid(), f->op, f->val);
                         break;
                 case AUDIT_GID:
-                        result = audit_comparator(cb->creds.gid, f->op, f->val);
+                        result = audit_comparator(current_gid(), f->op, f->val);
                         break;
                 case AUDIT_LOGINUID:
                         result = audit_comparator(audit_get_loginuid(current),
@@ -1287,7 +1286,7 @@ static int audit_filter_user_rules(struct netlink_skb_parms *cb,
         return 1;
 }
 
-int audit_filter_user(struct netlink_skb_parms *cb)
+int audit_filter_user(void)
 {
         enum audit_state state = AUDIT_DISABLED;
         struct audit_entry *e;
@@ -1295,7 +1294,7 @@ int audit_filter_user(struct netlink_skb_parms *cb)
 
         rcu_read_lock();
         list_for_each_entry_rcu(e, &audit_filter_list[AUDIT_FILTER_USER], list) {
-                if (audit_filter_user_rules(cb, &e->rule, &state)) {
+                if (audit_filter_user_rules(&e->rule, &state)) {
                         if (state == AUDIT_DISABLED)
                                 ret = 0;
                         break;