nf: xt_qtaguid: fix handling for cases where tunnels are used.

* fix skb->dev vs par->in/out
When there is some forwarding going on, it introduces extra state
around devs associated with xt_action_param->in/out and sk_buff->dev.
E.g.
   par->in and par->out are both set, or
   skb->dev and par->out are both set (and different)
This would lead qtaguid to make the wrong assumption about the
direction and update the wrong device stats.
Now we rely more on par->in/out.

* Fix handling when qtaguid is used as "owner"
When qtaguid is used as an owner module, and sk_socket->file is
not there (happens when tunnels are involved), it would
incorrectly do a tag stats update.

* Correct debug messages.

Bug: 11687690
Change-Id: I2b1ff8bd7131969ce9e25f8291d83a6280b3ba7f
CRs-Fixed: 747810
Signed-off-by: JP Abgrall <jpa@google.com>
Git-commit: 2b71479d6f5fe8f33b335f713380f72037244395
Git-repo: https://www.codeaurora.org/cgit/quic/la/kernel/mediatek
[imaund@codeaurora.org: Resolved trivial context conflicts.]
Signed-off-by: Ian Maund <imaund@codeaurora.org>
[bflowers@codeaurora.org: Resolved merge conflicts]
Signed-off-by: Bryse Flowers <bflowers@codeaurora.org>

net/netfilter/xt_qtaguid.c

@@ -1175,6 +1175,38 @@ static void iface_stat_update(struct net_device *net_dev, bool stash_only)
 	spin_unlock_bh(&iface_stat_list_lock);
 }
 
+/* Guarantied to return a net_device that has a name */
+static void get_dev_and_dir(const struct sk_buff *skb,
+			    struct xt_action_param *par,
+			    enum ifs_tx_rx *direction,
+			    const struct net_device **el_dev)
+{
+	BUG_ON(!direction || !el_dev);
+
+	if (par->in) {
+		*el_dev = par->in;
+		*direction = IFS_RX;
+	} else if (par->out) {
+		*el_dev = par->out;
+		*direction = IFS_TX;
+	} else {
+		pr_err("qtaguid[%d]: %s(): no par->in/out?!!\n",
+		       par->hooknum, __func__);
+		BUG();
+	}
+	if (unlikely(!(*el_dev)->name)) {
+		pr_err("qtaguid[%d]: %s(): no dev->name?!!\n",
+		       par->hooknum, __func__);
+		BUG();
+	}
+	if (skb->dev && *el_dev != skb->dev) {
+		MT_DEBUG("qtaguid[%d]: skb->dev=%p %s vs par->%s=%p %s\n",
+			 par->hooknum, skb->dev, skb->dev->name,
+			 *direction == IFS_RX ? "in" : "out",  *el_dev,
+			 (*el_dev)->name);
+	}
+}
+
 /*
  * Update stats for the specified interface from the skb.
  * Do nothing if the entry
@@ -1186,50 +1218,27 @@ static void iface_stat_update_from_skb(const struct sk_buff *skb,
 {
 	struct iface_stat *entry;
 	const struct net_device *el_dev;
-	enum ifs_tx_rx direction = par->in ? IFS_RX : IFS_TX;
+	enum ifs_tx_rx direction;
 	int bytes = skb->len;
 	int proto;
 
-	if (!skb->dev) {
-		MT_DEBUG("qtaguid[%d]: no skb->dev\n", par->hooknum);
-		el_dev = par->in ? : par->out;
-	} else {
-		const struct net_device *other_dev;
-		el_dev = skb->dev;
-		other_dev = par->in ? : par->out;
-		if (el_dev != other_dev) {
-			MT_DEBUG("qtaguid[%d]: skb->dev=%p %s vs "
-				 "par->(in/out)=%p %s\n",
-				 par->hooknum, el_dev, el_dev->name, other_dev,
-				 other_dev->name);
-		}
-	}
-
-	if (unlikely(!el_dev)) {
-		pr_err_ratelimited("qtaguid[%d]: %s(): no par->in/out?!!\n",
-				   par->hooknum, __func__);
-		BUG();
-	} else if (unlikely(!el_dev->name)) {
-		pr_err_ratelimited("qtaguid[%d]: %s(): no dev->name?!!\n",
-				   par->hooknum, __func__);
-		BUG();
-	} else {
-		proto = ipx_proto(skb, par);
-		MT_DEBUG("qtaguid[%d]: dev name=%s type=%d fam=%d proto=%d\n",
-			 par->hooknum, el_dev->name, el_dev->type,
-			 par->family, proto);
-	}
+	get_dev_and_dir(skb, par, &direction, &el_dev);
+	proto = ipx_proto(skb, par);
+	MT_DEBUG("qtaguid[%d]: iface_stat: %s(%s): "
+		 "type=%d fam=%d proto=%d dir=%d\n",
+		 par->hooknum, __func__, el_dev->name, el_dev->type,
+		 par->family, proto, direction);
 
 	spin_lock_bh(&iface_stat_list_lock);
 	entry = get_iface_entry(el_dev->name);
 	if (entry == NULL) {
-		IF_DEBUG("qtaguid: iface_stat: %s(%s): not tracked\n",
-			 __func__, el_dev->name);
+		IF_DEBUG("qtaguid[%d]: iface_stat: %s(%s): not tracked\n",
+			 par->hooknum, __func__, el_dev->name);
 		spin_unlock_bh(&iface_stat_list_lock);
 		return;
 	}
 
-	IF_DEBUG("qtaguid: %s(%s): entry=%p\n", __func__,
+	IF_DEBUG("qtaguid[%d]: %s(%s): entry=%p\n", par->hooknum,  __func__,
 		 el_dev->name, entry);
 
 	data_counters_update(&entry->totals_via_skb, 0, direction, proto,
@@ -1294,14 +1303,14 @@ static void if_tag_stat_update(const char *ifname, uid_t uid,
 	spin_lock_bh(&iface_stat_list_lock);
 	iface_entry = get_iface_entry(ifname);
 	if (!iface_entry) {
-		pr_err_ratelimited("qtaguid: iface_stat: stat_update() "
+		pr_err_ratelimited("qtaguid: tag_stat: stat_update() "
 				   "%s not found\n", ifname);
 		spin_unlock_bh(&iface_stat_list_lock);
 		return;
 	}
 	/* It is ok to process data when an iface_entry is inactive */
 
-	MT_DEBUG("qtaguid: iface_stat: stat_update() dev=%s entry=%p\n",
+	MT_DEBUG("qtaguid: tag_stat: stat_update() dev=%s entry=%p\n",
 		 ifname, iface_entry);
 
 	/*
@@ -1318,7 +1327,7 @@ static void if_tag_stat_update(const char *ifname, uid_t uid,
 		tag = combine_atag_with_uid(acct_tag, uid);
 		uid_tag = make_tag_from_uid(uid);
 	}
-	MT_DEBUG("qtaguid: iface_stat: stat_update(): "
+	MT_DEBUG("qtaguid: tag_stat: stat_update(): "
 		 " looking for tag=0x%llx (uid=%u) in ife=%p\n",
 		 tag, get_uid_from_tag(tag), iface_entry);
 	/* Loop over tag list under this interface for {acct_tag,uid_tag} */
@@ -1578,8 +1587,8 @@ static struct sock *qtaguid_find_sk(const struct sk_buff *skb,
 	struct sock *sk;
 	unsigned int hook_mask = (1 << par->hooknum);
 
-	MT_DEBUG("qtaguid: find_sk(skb=%p) hooknum=%d family=%d\n", skb,
-		 par->hooknum, par->family);
+	MT_DEBUG("qtaguid[%d]: find_sk(skb=%p) family=%d\n",
+		 par->hooknum, skb, par->family);
 
 	/*
 	 * Let's not abuse the the xt_socket_get*_sk(), or else it will
@@ -1600,8 +1609,8 @@ static struct sock *qtaguid_find_sk(const struct sk_buff *skb,
 	}
 
 	if (sk) {
-		MT_DEBUG("qtaguid: %p->sk_proto=%u "
-			 "->sk_state=%d\n", sk, sk->sk_protocol, sk->sk_state);
+		MT_DEBUG("qtaguid[%d]: %p->sk_proto=%u->sk_state=%d\n",
+			 par->hooknum, sk, sk->sk_protocol, sk->sk_state);
 		/*
 		 * When in TCP_TIME_WAIT the sk is not a "struct sock" but
 		 * "struct inet_timewait_sock" which is missing fields.
@@ -1619,37 +1628,19 @@ static void account_for_uid(const struct sk_buff *skb,
 			    struct xt_action_param *par)
 {
 	const struct net_device *el_dev;
+	enum ifs_tx_rx direction;
+	int proto;
 
-	if (!skb->dev) {
-		MT_DEBUG("qtaguid[%d]: no skb->dev\n", par->hooknum);
-		el_dev = par->in ? : par->out;
-	} else {
-		const struct net_device *other_dev;
-		el_dev = skb->dev;
-		other_dev = par->in ? : par->out;
-		if (el_dev != other_dev) {
-			MT_DEBUG("qtaguid[%d]: skb->dev=%p %s vs "
-				"par->(in/out)=%p %s\n",
-				par->hooknum, el_dev, el_dev->name, other_dev,
-				other_dev->name);
-		}
-	}
+	get_dev_and_dir(skb, par, &direction, &el_dev);
+	proto = ipx_proto(skb, par);
+	MT_DEBUG("qtaguid[%d]: dev name=%s type=%d fam=%d proto=%d dir=%d\n",
+		 par->hooknum, el_dev->name, el_dev->type,
+		 par->family, proto, direction);
 
-	if (unlikely(!el_dev)) {
-		pr_info("qtaguid[%d]: no par->in/out?!!\n", par->hooknum);
-	} else if (unlikely(!el_dev->name)) {
-		pr_info("qtaguid[%d]: no dev->name?!!\n", par->hooknum);
-	} else {
-		int proto = ipx_proto(skb, par);
-		MT_DEBUG("qtaguid[%d]: dev name=%s type=%d fam=%d proto=%d\n",
-			 par->hooknum, el_dev->name, el_dev->type,
-			 par->family, proto);
-
-		if_tag_stat_update(el_dev->name, uid,
-				skb->sk ? skb->sk : alternate_sk,
-				par->in ? IFS_RX : IFS_TX,
-				proto, skb->len);
-	}
+	if_tag_stat_update(el_dev->name, uid,
+			   skb->sk ? skb->sk : alternate_sk,
+			   direction,
+			   proto, skb->len);
 }
 
 static bool qtaguid_mt(const struct sk_buff *skb, struct xt_action_param *par)
@@ -1661,6 +1652,11 @@ static bool qtaguid_mt(const struct sk_buff *skb, struct xt_action_param *par)
 	kuid_t sock_uid;
 	bool res;
 	bool set_sk_callback_lock = false;
+	/*
+	 * TODO: unhack how to force just accounting.
+	 * For now we only do tag stats when the uid-owner is not requested
+	 */
+	bool do_tag_stat = !(info->match & XT_QTAGUID_UID);
 
 	if (unlikely(module_passive))
 		return (info->match ^ info->invert) == 0;
@@ -1734,12 +1730,7 @@ static bool qtaguid_mt(const struct sk_buff *skb, struct xt_action_param *par)
 		 * couldn't find the owner, so for now we just count them
 		 * against the system.
 		 */
-		/*
-		 * TODO: unhack how to force just accounting.
-		 * For now we only do iface stats when the uid-owner is not
-		 * requested.
-		 */
-		if (!(info->match & XT_QTAGUID_UID))
+		if (do_tag_stat)
 			account_for_uid(skb, sk, 0, par);
 		MT_DEBUG("qtaguid[%d]: leaving (sk?sk->sk_socket)=%p\n",
 			par->hooknum,
@@ -1754,18 +1745,15 @@ static bool qtaguid_mt(const struct sk_buff *skb, struct xt_action_param *par)
 	filp = sk->sk_socket->file;
 	if (filp == NULL) {
 		MT_DEBUG("qtaguid[%d]: leaving filp=NULL\n", par->hooknum);
-		account_for_uid(skb, sk, 0, par);
+		if (do_tag_stat)
+			account_for_uid(skb, sk, 0, par);
 		res = ((info->match ^ info->invert) &
 			(XT_QTAGUID_UID | XT_QTAGUID_GID)) == 0;
 		atomic64_inc(&qtu_events.match_no_sk_file);
 		goto put_sock_ret_res;
 	}
 	sock_uid = filp->f_cred->fsuid;
-	/*
-	 * TODO: unhack how to force just accounting.
-	 * For now we only do iface stats when the uid-owner is not requested
-	 */
-	if (!(info->match & XT_QTAGUID_UID))
+	if (do_tag_stat)
 		account_for_uid(skb, sk, from_kuid(&init_user_ns, sock_uid), par);
 
 	/*