Re: [patch net-next 03/12] ipmr: Add FIB notification access functions
From: Nikolay Aleksandrov <hidden>
Date: 2017-09-21 11:19:14
On 21/09/17 09:43, Jiri Pirko wrote:
From: Yotam Gigi <redacted> Make the ipmr module register as a FIB notifier. To do that, implement both the ipmr_seq_read and ipmr_dump ops. The ipmr_seq_read op returns a sequence counter that is incremented on every notification related operation done by the ipmr. To implement that, add a sequence counter in the netns_ipv4 struct and increment it whenever a new MFC route or VIF are added or deleted. The sequence operations are protected by the RTNL lock. The ipmr_dump iterates the list of MFC routes and the list of VIF entries and sends notifications about them. The entries dump is done under RCU. Signed-off-by: Yotam Gigi <redacted> Reviewed-by: Ido Schimmel <redacted> Signed-off-by: Jiri Pirko <redacted> --- include/linux/mroute.h | 15 ++++++ include/net/netns/ipv4.h | 3 ++ net/ipv4/ipmr.c | 135 ++++++++++++++++++++++++++++++++++++++++++++++- 3 files changed, 151 insertions(+), 2 deletions(-)
[snip]
+
+static int ipmr_dump(struct net *net, struct notifier_block *nb)
+{
+ struct mr_table *mrt;
+ int err;
+
+ err = ipmr_rules_dump(net, nb);
+ if (err)
+ return err;
+
+ ipmr_for_each_table(mrt, net) {
+ struct vif_device *v = &mrt->vif_table[0];
+ struct mfc_cache *mfc;
+ int vifi;
+
+ /* Notifiy on table VIF entries */
+ for (vifi = 0; vifi < mrt->maxvif; vifi++, v++) {
+ if (!v->dev)
+ continue;
+
+ call_ipmr_vif_entry_notifier(nb, net, FIB_EVENT_VIF_ADD,
+ v, vifi, mrt->id);
+ }The VIF table is protected by mrt_lock (rwlock), here with RCU only you're not guaranteed to keep v->dev. It can become NULL after the check above. For details you can see vif_delete() in net/ipv4/ipmr.c. You need at least mrt_lock for reading.
quoted hunk ↗ jump to hunk
+ + /* Notify on table MFC entries */ + list_for_each_entry_rcu(mfc, &mrt->mfc_cache_list, list) + call_ipmr_mfc_entry_notifier(nb, net, + FIB_EVENT_ENTRY_ADD, mfc, + mrt->id); + } + + return 0; +} + +static const struct fib_notifier_ops ipmr_notifier_ops_template = { + .family = RTNL_FAMILY_IPMR, + .fib_seq_read = ipmr_seq_read, + .fib_dump = ipmr_dump, + .owner = THIS_MODULE, +}; + +int __net_init ipmr_notifier_init(struct net *net) +{ + struct fib_notifier_ops *ops; + + net->ipv4.ipmr_seq = 0; + + ops = fib_notifier_ops_register(&ipmr_notifier_ops_template, net); + if (IS_ERR(ops)) + return PTR_ERR(ops); + net->ipv4.ipmr_notifier_ops = ops; + + return 0; +} + +static void __net_exit ipmr_notifier_exit(struct net *net) +{ + fib_notifier_ops_unregister(net->ipv4.ipmr_notifier_ops); + net->ipv4.ipmr_notifier_ops = NULL; +} + /* Setup for IP multicast routing */ static int __net_init ipmr_net_init(struct net *net) { int err; + err = ipmr_notifier_init(net); + if (err) + goto ipmr_notifier_fail; + err = ipmr_rules_init(net); if (err < 0) - goto fail; + goto ipmr_rules_fail; #ifdef CONFIG_PROC_FS err = -ENOMEM;@@ -3074,7 +3202,9 @@ static int __net_init ipmr_net_init(struct net *net) proc_vif_fail: ipmr_rules_exit(net); #endif -fail: +ipmr_rules_fail: + ipmr_notifier_exit(net); +ipmr_notifier_fail: return err; }@@ -3084,6 +3214,7 @@ static void __net_exit ipmr_net_exit(struct net *net) remove_proc_entry("ip_mr_cache", net->proc_net); remove_proc_entry("ip_mr_vif", net->proc_net); #endif + ipmr_notifier_exit(net); ipmr_rules_exit(net); }