netfilter: xt_qtaguid: warn only once for missing proc qtaguid data

When a process doesn't have /dev/xt_qtaguid open, only warn once
instead of for every ctrl access.

Change-Id: I98a462a8731254ddc3bf6d2fefeef9823659b1f0
Signed-off-by: JP Abgrall <jpa@google.com>

diff --git a/net/netfilter/xt_qtaguid.c b/net/netfilter/xt_qtaguid.c
index dff2ff3fd7cc8ce76e00c060e5f500dd92a2eb75..66eab3a9c4a47316b56f9febf37b3fc50c5ac4e2 100644 (file)
--- a/net/netfilter/xt_qtaguid.c
+++ b/net/netfilter/xt_qtaguid.c
@@ -1947,8 +1947,15 @@ static int ctrl_cmd_tag(const char *input)
                spin_lock_bh(&uid_tag_data_tree_lock);
                pqd_entry = proc_qtu_data_tree_search(
                        &proc_qtu_data_tree, current->tgid);
-               /* TODO: remove if() test, do BUG_ON() */
-               WARN_ON(IS_ERR_OR_NULL(pqd_entry));
+               /*
+                * TODO: remove if, and start failing.
+                * At first, we want to catch user-space code that is not
+                * opening the /dev/xt_qtaguid.
+                */
+               WARN_ONCE(IS_ERR_OR_NULL(pqd_entry),
+                         "qtaguid: User space forgot to open /dev/xt_qtaguid? "
+                         "pid=%u tgid=%u uid=%u\n",
+                         current->pid, current->tgid, current_fsuid());
                if (!IS_ERR_OR_NULL(pqd_entry)) {
                        list_add(&sock_tag_entry->list,
                                 &pqd_entry->sock_tag_list);
@@ -2027,8 +2034,15 @@ static int ctrl_cmd_untag(const char *input)
        spin_lock_bh(&uid_tag_data_tree_lock);
        pqd_entry = proc_qtu_data_tree_search(
                &proc_qtu_data_tree, current->tgid);
-       /* TODO: remove if() test, do BUG_ON() */
-       WARN_ON(IS_ERR_OR_NULL(pqd_entry));
+       /*
+        * TODO: remove if, and start failing.
+        * At first, we want to catch user-space code that is not
+        * opening the /dev/xt_qtaguid.
+        */
+       WARN_ONCE(IS_ERR_OR_NULL(pqd_entry),
+                 "qtaguid: User space forgot to open /dev/xt_qtaguid? "
+                 "pid=%u tgid=%u uid=%u\n",
+                 current->pid, current->tgid, current_fsuid());
        if (!IS_ERR_OR_NULL(pqd_entry))
                list_del(&sock_tag_entry->list);
        spin_unlock_bh(&uid_tag_data_tree_lock);