From 7d4741eacdefa5f0475431645b56baf00784df1f Mon Sep 17 00:00:00 2001 From: Benjamin Poirier Date: Mon, 29 Nov 2021 15:15:05 +0900 Subject: net: mpls: Fix notifications when deleting a device There are various problems related to netlink notifications for mpls route changes in response to interfaces being deleted: * delete interface of only nexthop DELROUTE notification is missing RTA_OIF attribute * delete interface of non-last nexthop NEWROUTE notification is missing entirely * delete interface of last nexthop DELROUTE notification is missing nexthop All of these problems stem from the fact that existing routes are modified in-place before sending a notification. Restructure mpls_ifdown() to avoid changing the route in the DELROUTE cases and to create a copy in the NEWROUTE case. Fixes: f8efb73c97e2 ("mpls: multipath route support") Signed-off-by: Benjamin Poirier Signed-off-by: David S. Miller --- net/mpls/af_mpls.c | 68 +++++++++++++++++++++++++++++++++++++++++------------- 1 file changed, 52 insertions(+), 16 deletions(-) (limited to 'net/mpls') diff --git a/net/mpls/af_mpls.c b/net/mpls/af_mpls.c index ffeb2df8be7a..6e587feb705c 100644 --- a/net/mpls/af_mpls.c +++ b/net/mpls/af_mpls.c @@ -1491,22 +1491,52 @@ static void mpls_dev_destroy_rcu(struct rcu_head *head) kfree(mdev); } -static void mpls_ifdown(struct net_device *dev, int event) +static int mpls_ifdown(struct net_device *dev, int event) { struct mpls_route __rcu **platform_label; struct net *net = dev_net(dev); - u8 alive, deleted; unsigned index; platform_label = rtnl_dereference(net->mpls.platform_label); for (index = 0; index < net->mpls.platform_labels; index++) { struct mpls_route *rt = rtnl_dereference(platform_label[index]); + bool nh_del = false; + u8 alive = 0; if (!rt) continue; - alive = 0; - deleted = 0; + if (event == NETDEV_UNREGISTER) { + u8 deleted = 0; + + for_nexthops(rt) { + struct net_device *nh_dev = + rtnl_dereference(nh->nh_dev); + + if (!nh_dev || nh_dev == dev) + deleted++; + if (nh_dev == dev) + nh_del = true; + } endfor_nexthops(rt); + + /* if there are no more nexthops, delete the route */ + if (deleted == rt->rt_nhn) { + mpls_route_update(net, index, NULL, NULL); + continue; + } + + if (nh_del) { + size_t size = sizeof(*rt) + rt->rt_nhn * + rt->rt_nh_size; + struct mpls_route *orig = rt; + + rt = kmalloc(size, GFP_KERNEL); + if (!rt) + return -ENOMEM; + memcpy(rt, orig, size); + } + } + change_nexthops(rt) { unsigned int nh_flags = nh->nh_flags; @@ -1530,16 +1560,15 @@ static void mpls_ifdown(struct net_device *dev, int event) next: if (!(nh_flags & (RTNH_F_DEAD | RTNH_F_LINKDOWN))) alive++; - if (!rtnl_dereference(nh->nh_dev)) - deleted++; } endfor_nexthops(rt); WRITE_ONCE(rt->rt_nhn_alive, alive); - /* if there are no more nexthops, delete the route */ - if (event == NETDEV_UNREGISTER && deleted == rt->rt_nhn) - mpls_route_update(net, index, NULL, NULL); + if (nh_del) + mpls_route_update(net, index, rt, NULL); } + + return 0; } static void mpls_ifup(struct net_device *dev, unsigned int flags) @@ -1597,8 +1626,12 @@ static int mpls_dev_notify(struct notifier_block *this, unsigned long event, return NOTIFY_OK; switch (event) { + int err; + case NETDEV_DOWN: - mpls_ifdown(dev, event); + err = mpls_ifdown(dev, event); + if (err) + return notifier_from_errno(err); break; case NETDEV_UP: flags = dev_get_flags(dev); @@ -1609,13 +1642,18 @@ static int mpls_dev_notify(struct notifier_block *this, unsigned long event, break; case NETDEV_CHANGE: flags = dev_get_flags(dev); - if (flags & (IFF_RUNNING | IFF_LOWER_UP)) + if (flags & (IFF_RUNNING | IFF_LOWER_UP)) { mpls_ifup(dev, RTNH_F_DEAD | RTNH_F_LINKDOWN); - else - mpls_ifdown(dev, event); + } else { + err = mpls_ifdown(dev, event); + if (err) + return notifier_from_errno(err); + } break; case NETDEV_UNREGISTER: - mpls_ifdown(dev, event); + err = mpls_ifdown(dev, event); + if (err) + return notifier_from_errno(err); mdev = mpls_dev_get(dev); if (mdev) { mpls_dev_sysctl_unregister(dev, mdev); @@ -1626,8 +1664,6 @@ static int mpls_dev_notify(struct notifier_block *this, unsigned long event, case NETDEV_CHANGENAME: mdev = mpls_dev_get(dev); if (mdev) { - int err; - mpls_dev_sysctl_unregister(dev, mdev); err = mpls_dev_sysctl_register(dev, mdev); if (err) -- cgit v1.2.3 From 189168181bb67825a14e8083d1503cfdc2891ebf Mon Sep 17 00:00:00 2001 From: Benjamin Poirier Date: Mon, 29 Nov 2021 15:15:06 +0900 Subject: net: mpls: Remove rcu protection from nh_dev Following the previous commit, nh_dev can no longer be accessed and modified concurrently. Signed-off-by: Benjamin Poirier Signed-off-by: David S. Miller --- net/mpls/af_mpls.c | 39 +++++++++++++++------------------------ net/mpls/internal.h | 2 +- 2 files changed, 16 insertions(+), 25 deletions(-) (limited to 'net/mpls') diff --git a/net/mpls/af_mpls.c b/net/mpls/af_mpls.c index 6e587feb705c..0c7bde1c14a6 100644 --- a/net/mpls/af_mpls.c +++ b/net/mpls/af_mpls.c @@ -409,7 +409,7 @@ static int mpls_forward(struct sk_buff *skb, struct net_device *dev, goto err; /* Find the output device */ - out_dev = rcu_dereference(nh->nh_dev); + out_dev = nh->nh_dev; if (!mpls_output_possible(out_dev)) goto tx_err; @@ -698,7 +698,7 @@ static int mpls_nh_assign_dev(struct net *net, struct mpls_route *rt, (dev->addr_len != nh->nh_via_alen)) goto errout; - RCU_INIT_POINTER(nh->nh_dev, dev); + nh->nh_dev = dev; if (!(dev->flags & IFF_UP)) { nh->nh_flags |= RTNH_F_DEAD; @@ -1510,12 +1510,9 @@ static int mpls_ifdown(struct net_device *dev, int event) u8 deleted = 0; for_nexthops(rt) { - struct net_device *nh_dev = - rtnl_dereference(nh->nh_dev); - - if (!nh_dev || nh_dev == dev) + if (!nh->nh_dev || nh->nh_dev == dev) deleted++; - if (nh_dev == dev) + if (nh->nh_dev == dev) nh_del = true; } endfor_nexthops(rt); @@ -1540,7 +1537,7 @@ static int mpls_ifdown(struct net_device *dev, int event) change_nexthops(rt) { unsigned int nh_flags = nh->nh_flags; - if (rtnl_dereference(nh->nh_dev) != dev) + if (nh->nh_dev != dev) goto next; switch (event) { @@ -1553,7 +1550,7 @@ static int mpls_ifdown(struct net_device *dev, int event) break; } if (event == NETDEV_UNREGISTER) - RCU_INIT_POINTER(nh->nh_dev, NULL); + nh->nh_dev = NULL; if (nh->nh_flags != nh_flags) WRITE_ONCE(nh->nh_flags, nh_flags); @@ -1588,14 +1585,12 @@ static void mpls_ifup(struct net_device *dev, unsigned int flags) alive = 0; change_nexthops(rt) { unsigned int nh_flags = nh->nh_flags; - struct net_device *nh_dev = - rtnl_dereference(nh->nh_dev); if (!(nh_flags & flags)) { alive++; continue; } - if (nh_dev != dev) + if (nh->nh_dev != dev) continue; alive++; nh_flags &= ~flags; @@ -2030,7 +2025,7 @@ static int mpls_dump_route(struct sk_buff *skb, u32 portid, u32 seq, int event, nla_put_via(skb, nh->nh_via_table, mpls_nh_via(rt, nh), nh->nh_via_alen)) goto nla_put_failure; - dev = rtnl_dereference(nh->nh_dev); + dev = nh->nh_dev; if (dev && nla_put_u32(skb, RTA_OIF, dev->ifindex)) goto nla_put_failure; if (nh->nh_flags & RTNH_F_LINKDOWN) @@ -2048,7 +2043,7 @@ static int mpls_dump_route(struct sk_buff *skb, u32 portid, u32 seq, int event, goto nla_put_failure; for_nexthops(rt) { - dev = rtnl_dereference(nh->nh_dev); + dev = nh->nh_dev; if (!dev) continue; @@ -2159,18 +2154,14 @@ static int mpls_valid_fib_dump_req(struct net *net, const struct nlmsghdr *nlh, static bool mpls_rt_uses_dev(struct mpls_route *rt, const struct net_device *dev) { - struct net_device *nh_dev; - if (rt->rt_nhn == 1) { struct mpls_nh *nh = rt->rt_nh; - nh_dev = rtnl_dereference(nh->nh_dev); - if (dev == nh_dev) + if (nh->nh_dev == dev) return true; } else { for_nexthops(rt) { - nh_dev = rtnl_dereference(nh->nh_dev); - if (nh_dev == dev) + if (nh->nh_dev == dev) return true; } endfor_nexthops(rt); } @@ -2258,7 +2249,7 @@ static inline size_t lfib_nlmsg_size(struct mpls_route *rt) size_t nhsize = 0; for_nexthops(rt) { - if (!rtnl_dereference(nh->nh_dev)) + if (!nh->nh_dev) continue; nhsize += nla_total_size(sizeof(struct rtnexthop)); /* RTA_VIA */ @@ -2504,7 +2495,7 @@ static int mpls_getroute(struct sk_buff *in_skb, struct nlmsghdr *in_nlh, nla_put_via(skb, nh->nh_via_table, mpls_nh_via(rt, nh), nh->nh_via_alen)) goto nla_put_failure; - dev = rtnl_dereference(nh->nh_dev); + dev = nh->nh_dev; if (dev && nla_put_u32(skb, RTA_OIF, dev->ifindex)) goto nla_put_failure; @@ -2543,7 +2534,7 @@ static int resize_platform_label_table(struct net *net, size_t limit) rt0 = mpls_rt_alloc(1, lo->addr_len, 0); if (IS_ERR(rt0)) goto nort0; - RCU_INIT_POINTER(rt0->rt_nh->nh_dev, lo); + rt0->rt_nh->nh_dev = lo; rt0->rt_protocol = RTPROT_KERNEL; rt0->rt_payload_type = MPT_IPV4; rt0->rt_ttl_propagate = MPLS_TTL_PROP_DEFAULT; @@ -2557,7 +2548,7 @@ static int resize_platform_label_table(struct net *net, size_t limit) rt2 = mpls_rt_alloc(1, lo->addr_len, 0); if (IS_ERR(rt2)) goto nort2; - RCU_INIT_POINTER(rt2->rt_nh->nh_dev, lo); + rt2->rt_nh->nh_dev = lo; rt2->rt_protocol = RTPROT_KERNEL; rt2->rt_payload_type = MPT_IPV6; rt2->rt_ttl_propagate = MPLS_TTL_PROP_DEFAULT; diff --git a/net/mpls/internal.h b/net/mpls/internal.h index 838cdfc10e47..893df00b77b6 100644 --- a/net/mpls/internal.h +++ b/net/mpls/internal.h @@ -87,7 +87,7 @@ enum mpls_payload_type { }; struct mpls_nh { /* next hop label forwarding entry */ - struct net_device __rcu *nh_dev; + struct net_device *nh_dev; /* nh_flags is accessed under RCU in the packet path; it is * modified handling netdev events with rtnl lock held -- cgit v1.2.3