From ebc3197963fc42841b183d0280bd3f9f85f13c30 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Thu, 23 Jun 2022 04:34:32 +0000 Subject: [PATCH] ipmr: add rcu protection over (struct vif_device)->dev We will soon use RCU instead of rwlock in ipmr & ip6mr This preliminary patch adds proper rcu verbs to read/write (struct vif_device)->dev Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller --- include/linux/mroute_base.h | 11 ++++--- net/ipv4/ipmr.c | 65 ++++++++++++++++++++++--------------- net/ipv4/ipmr_base.c | 47 +++++++++++++++++---------- net/ipv6/ip6mr.c | 65 ++++++++++++++++++++----------------- 4 files changed, 111 insertions(+), 77 deletions(-) diff --git a/include/linux/mroute_base.h b/include/linux/mroute_base.h index e05ee9f001ff..10d1e4fb4e9f 100644 --- a/include/linux/mroute_base.h +++ b/include/linux/mroute_base.h @@ -26,7 +26,7 @@ * @remote: Remote address for tunnels */ struct vif_device { - struct net_device *dev; + struct net_device __rcu *dev; netdevice_tracker dev_tracker; unsigned long bytes_in, bytes_out; unsigned long pkt_in, pkt_out; @@ -52,6 +52,7 @@ static inline int mr_call_vif_notifier(struct notifier_block *nb, unsigned short family, enum fib_event_type event_type, struct vif_device *vif, + struct net_device *vif_dev, unsigned short vif_index, u32 tb_id, struct netlink_ext_ack *extack) { @@ -60,7 +61,7 @@ static inline int mr_call_vif_notifier(struct notifier_block *nb, .family = family, .extack = extack, }, - .dev = vif->dev, + .dev = vif_dev, .vif_index = vif_index, .vif_flags = vif->flags, .tb_id = tb_id, @@ -73,6 +74,7 @@ static inline int mr_call_vif_notifiers(struct net *net, unsigned short family, enum fib_event_type event_type, struct vif_device *vif, + struct net_device *vif_dev, unsigned short vif_index, u32 tb_id, unsigned int *ipmr_seq) { @@ -80,7 +82,7 @@ static inline int mr_call_vif_notifiers(struct net *net, .info = { .family = family, }, - .dev = vif->dev, + .dev = vif_dev, .vif_index = vif_index, .vif_flags = vif->flags, .tb_id = tb_id, @@ -98,7 +100,8 @@ static inline int mr_call_vif_notifiers(struct net *net, #define MAXVIFS 32 #endif -#define VIF_EXISTS(_mrt, _idx) (!!((_mrt)->vif_table[_idx].dev)) +/* Note: This helper is deprecated. */ +#define VIF_EXISTS(_mrt, _idx) (!!rcu_access_pointer((_mrt)->vif_table[_idx].dev)) /* mfc_flags: * MFC_STATIC - the entry was added statically (not by a routing daemon) diff --git a/net/ipv4/ipmr.c b/net/ipv4/ipmr.c index 8324e541d193..10371a9e78fc 100644 --- a/net/ipv4/ipmr.c +++ b/net/ipv4/ipmr.c @@ -79,6 +79,12 @@ struct ipmr_result { static DEFINE_RWLOCK(mrt_lock); +static struct net_device *vif_dev_read(const struct vif_device *vif) +{ + return rcu_dereference_check(vif->dev, + lockdep_is_held(&mrt_lock)); +} + /* Multicast router control variables */ /* Special spinlock for queue of unresolved entries */ @@ -586,7 +592,7 @@ static int __pim_rcv(struct mr_table *mrt, struct sk_buff *skb, read_lock(&mrt_lock); if (mrt->mroute_reg_vif_num >= 0) - reg_dev = mrt->vif_table[mrt->mroute_reg_vif_num].dev; + reg_dev = vif_dev_read(&mrt->vif_table[mrt->mroute_reg_vif_num]); read_unlock(&mrt_lock); if (!reg_dev) @@ -614,10 +620,11 @@ static struct net_device *ipmr_reg_vif(struct net *net, struct mr_table *mrt) static int call_ipmr_vif_entry_notifiers(struct net *net, enum fib_event_type event_type, struct vif_device *vif, + struct net_device *vif_dev, vifi_t vif_index, u32 tb_id) { return mr_call_vif_notifiers(net, RTNL_FAMILY_IPMR, event_type, - vif, vif_index, tb_id, + vif, vif_dev, vif_index, tb_id, &net->ipv4.ipmr_seq); } @@ -649,18 +656,14 @@ static int vif_delete(struct mr_table *mrt, int vifi, int notify, v = &mrt->vif_table[vifi]; - if (VIF_EXISTS(mrt, vifi)) - call_ipmr_vif_entry_notifiers(net, FIB_EVENT_VIF_DEL, v, vifi, - mrt->id); + dev = rtnl_dereference(v->dev); + if (!dev) + return -EADDRNOTAVAIL; write_lock_bh(&mrt_lock); - dev = v->dev; - v->dev = NULL; - - if (!dev) { - write_unlock_bh(&mrt_lock); - return -EADDRNOTAVAIL; - } + call_ipmr_vif_entry_notifiers(net, FIB_EVENT_VIF_DEL, v, dev, + vifi, mrt->id); + RCU_INIT_POINTER(v->dev, NULL); if (vifi == mrt->mroute_reg_vif_num) mrt->mroute_reg_vif_num = -1; @@ -890,14 +893,15 @@ static int vif_add(struct net *net, struct mr_table *mrt, /* And finish update writing critical data */ write_lock_bh(&mrt_lock); - v->dev = dev; + rcu_assign_pointer(v->dev, dev); netdev_tracker_alloc(dev, &v->dev_tracker, GFP_ATOMIC); if (v->flags & VIFF_REGISTER) mrt->mroute_reg_vif_num = vifi; if (vifi+1 > mrt->maxvif) mrt->maxvif = vifi+1; write_unlock_bh(&mrt_lock); - call_ipmr_vif_entry_notifiers(net, FIB_EVENT_VIF_ADD, v, vifi, mrt->id); + call_ipmr_vif_entry_notifiers(net, FIB_EVENT_VIF_ADD, v, dev, + vifi, mrt->id); return 0; } @@ -1726,7 +1730,7 @@ static int ipmr_device_event(struct notifier_block *this, unsigned long event, v ipmr_for_each_table(mrt, net) { v = &mrt->vif_table[0]; for (ct = 0; ct < mrt->maxvif; ct++, v++) { - if (v->dev == dev) + if (rcu_access_pointer(v->dev) == dev) vif_delete(mrt, ct, 1, NULL); } } @@ -1811,19 +1815,21 @@ static void ipmr_queue_xmit(struct net *net, struct mr_table *mrt, { const struct iphdr *iph = ip_hdr(skb); struct vif_device *vif = &mrt->vif_table[vifi]; + struct net_device *vif_dev; struct net_device *dev; struct rtable *rt; struct flowi4 fl4; int encap = 0; - if (!vif->dev) + vif_dev = vif_dev_read(vif); + if (!vif_dev) goto out_free; if (vif->flags & VIFF_REGISTER) { vif->pkt_out++; vif->bytes_out += skb->len; - vif->dev->stats.tx_bytes += skb->len; - vif->dev->stats.tx_packets++; + vif_dev->stats.tx_bytes += skb->len; + vif_dev->stats.tx_packets++; ipmr_cache_report(mrt, skb, vifi, IGMPMSG_WHOLEPKT); goto out_free; } @@ -1881,8 +1887,8 @@ static void ipmr_queue_xmit(struct net *net, struct mr_table *mrt, if (vif->flags & VIFF_TUNNEL) { ip_encap(net, skb, vif->local, vif->remote); /* FIXME: extra output firewall step used to be here. --RR */ - vif->dev->stats.tx_packets++; - vif->dev->stats.tx_bytes += skb->len; + vif_dev->stats.tx_packets++; + vif_dev->stats.tx_bytes += skb->len; } IPCB(skb)->flags |= IPSKB_FORWARDED; @@ -1911,7 +1917,7 @@ static int ipmr_find_vif(struct mr_table *mrt, struct net_device *dev) int ct; for (ct = mrt->maxvif-1; ct >= 0; ct--) { - if (mrt->vif_table[ct].dev == dev) + if (rcu_access_pointer(mrt->vif_table[ct].dev) == dev) break; } return ct; @@ -1944,7 +1950,7 @@ static void ip_mr_forward(struct net *net, struct mr_table *mrt, } /* Wrong interface: drop packet and (maybe) send PIM assert. */ - if (mrt->vif_table[vif].dev != dev) { + if (rcu_access_pointer(mrt->vif_table[vif].dev) != dev) { if (rt_is_output_route(skb_rtable(skb))) { /* It is our own packet, looped back. * Very complicated situation... @@ -2744,18 +2750,21 @@ static bool ipmr_fill_table(struct mr_table *mrt, struct sk_buff *skb) static bool ipmr_fill_vif(struct mr_table *mrt, u32 vifid, struct sk_buff *skb) { + struct net_device *vif_dev; struct nlattr *vif_nest; struct vif_device *vif; + vif = &mrt->vif_table[vifid]; + vif_dev = vif_dev_read(vif); /* if the VIF doesn't exist just continue */ - if (!VIF_EXISTS(mrt, vifid)) + if (!vif_dev) return true; - vif = &mrt->vif_table[vifid]; vif_nest = nla_nest_start_noflag(skb, IPMRA_VIF); if (!vif_nest) return false; - if (nla_put_u32(skb, IPMRA_VIFA_IFINDEX, vif->dev->ifindex) || + + if (nla_put_u32(skb, IPMRA_VIFA_IFINDEX, vif_dev->ifindex) || nla_put_u32(skb, IPMRA_VIFA_VIF_ID, vifid) || nla_put_u16(skb, IPMRA_VIFA_FLAGS, vif->flags) || nla_put_u64_64bit(skb, IPMRA_VIFA_BYTES_IN, vif->bytes_in, @@ -2919,9 +2928,11 @@ static int ipmr_vif_seq_show(struct seq_file *seq, void *v) "Interface BytesIn PktsIn BytesOut PktsOut Flags Local Remote\n"); } else { const struct vif_device *vif = v; - const char *name = vif->dev ? - vif->dev->name : "none"; + const struct net_device *vif_dev; + const char *name; + vif_dev = vif_dev_read(vif); + name = vif_dev ? vif_dev->name : "none"; seq_printf(seq, "%2td %-10s %8ld %7ld %8ld %7ld %05X %08X %08X\n", vif - mrt->vif_table, diff --git a/net/ipv4/ipmr_base.c b/net/ipv4/ipmr_base.c index aa8738a91210..59f62b938472 100644 --- a/net/ipv4/ipmr_base.c +++ b/net/ipv4/ipmr_base.c @@ -13,7 +13,7 @@ void vif_device_init(struct vif_device *v, unsigned short flags, unsigned short get_iflink_mask) { - v->dev = NULL; + RCU_INIT_POINTER(v->dev, NULL); v->bytes_in = 0; v->bytes_out = 0; v->pkt_in = 0; @@ -208,6 +208,7 @@ EXPORT_SYMBOL(mr_mfc_seq_next); int mr_fill_mroute(struct mr_table *mrt, struct sk_buff *skb, struct mr_mfc *c, struct rtmsg *rtm) { + struct net_device *vif_dev; struct rta_mfc_stats mfcs; struct nlattr *mp_attr; struct rtnexthop *nhp; @@ -220,10 +221,13 @@ int mr_fill_mroute(struct mr_table *mrt, struct sk_buff *skb, return -ENOENT; } - if (VIF_EXISTS(mrt, c->mfc_parent) && - nla_put_u32(skb, RTA_IIF, - mrt->vif_table[c->mfc_parent].dev->ifindex) < 0) + rcu_read_lock(); + vif_dev = rcu_dereference(mrt->vif_table[c->mfc_parent].dev); + if (vif_dev && nla_put_u32(skb, RTA_IIF, vif_dev->ifindex) < 0) { + rcu_read_unlock(); return -EMSGSIZE; + } + rcu_read_unlock(); if (c->mfc_flags & MFC_OFFLOAD) rtm->rtm_flags |= RTNH_F_OFFLOAD; @@ -232,23 +236,27 @@ int mr_fill_mroute(struct mr_table *mrt, struct sk_buff *skb, if (!mp_attr) return -EMSGSIZE; + rcu_read_lock(); for (ct = c->mfc_un.res.minvif; ct < c->mfc_un.res.maxvif; ct++) { - if (VIF_EXISTS(mrt, ct) && c->mfc_un.res.ttls[ct] < 255) { - struct vif_device *vif; + struct vif_device *vif = &mrt->vif_table[ct]; + + vif_dev = rcu_dereference(vif->dev); + if (vif_dev && c->mfc_un.res.ttls[ct] < 255) { nhp = nla_reserve_nohdr(skb, sizeof(*nhp)); if (!nhp) { + rcu_read_unlock(); nla_nest_cancel(skb, mp_attr); return -EMSGSIZE; } nhp->rtnh_flags = 0; nhp->rtnh_hops = c->mfc_un.res.ttls[ct]; - vif = &mrt->vif_table[ct]; - nhp->rtnh_ifindex = vif->dev->ifindex; + nhp->rtnh_ifindex = vif_dev->ifindex; nhp->rtnh_len = sizeof(*nhp); } } + rcu_read_unlock(); nla_nest_end(skb, mp_attr); @@ -275,13 +283,14 @@ static bool mr_mfc_uses_dev(const struct mr_table *mrt, int ct; for (ct = c->mfc_un.res.minvif; ct < c->mfc_un.res.maxvif; ct++) { - if (VIF_EXISTS(mrt, ct) && c->mfc_un.res.ttls[ct] < 255) { - const struct vif_device *vif; + const struct net_device *vif_dev; + const struct vif_device *vif; - vif = &mrt->vif_table[ct]; - if (vif->dev == dev) - return true; - } + vif = &mrt->vif_table[ct]; + vif_dev = rcu_access_pointer(vif->dev); + if (vif_dev && c->mfc_un.res.ttls[ct] < 255 && + vif_dev == dev) + return true; } return false; } @@ -402,18 +411,22 @@ int mr_dump(struct net *net, struct notifier_block *nb, unsigned short family, for (mrt = mr_iter(net, NULL); mrt; mrt = mr_iter(net, mrt)) { struct vif_device *v = &mrt->vif_table[0]; + struct net_device *vif_dev; struct mr_mfc *mfc; int vifi; /* Notifiy on table VIF entries */ read_lock(mrt_lock); for (vifi = 0; vifi < mrt->maxvif; vifi++, v++) { - if (!v->dev) + vif_dev = rcu_dereference_check(v->dev, + lockdep_is_held(mrt_lock)); + if (!vif_dev) continue; err = mr_call_vif_notifier(nb, family, - FIB_EVENT_VIF_ADD, - v, vifi, mrt->id, extack); + FIB_EVENT_VIF_ADD, v, + vif_dev, vifi, + mrt->id, extack); if (err) break; } diff --git a/net/ipv6/ip6mr.c b/net/ipv6/ip6mr.c index aa66c032ba97..44cb3d88bbd6 100644 --- a/net/ipv6/ip6mr.c +++ b/net/ipv6/ip6mr.c @@ -64,6 +64,12 @@ struct ip6mr_result { static DEFINE_RWLOCK(mrt_lock); +static struct net_device *vif_dev_read(const struct vif_device *vif) +{ + return rcu_dereference_check(vif->dev, + lockdep_is_held(&mrt_lock)); +} + /* Multicast router control variables */ /* Special spinlock for queue of unresolved entries */ @@ -430,7 +436,11 @@ static int ip6mr_vif_seq_show(struct seq_file *seq, void *v) "Interface BytesIn PktsIn BytesOut PktsOut Flags\n"); } else { const struct vif_device *vif = v; - const char *name = vif->dev ? vif->dev->name : "none"; + const struct net_device *vif_dev; + const char *name; + + vif_dev = vif_dev_read(vif); + name = vif_dev ? vif_dev->name : "none"; seq_printf(seq, "%2td %-10s %8ld %7ld %8ld %7ld %05X\n", @@ -553,7 +563,7 @@ static int pim6_rcv(struct sk_buff *skb) read_lock(&mrt_lock); if (reg_vif_num >= 0) - reg_dev = mrt->vif_table[reg_vif_num].dev; + reg_dev = vif_dev_read(&mrt->vif_table[reg_vif_num]); read_unlock(&mrt_lock); if (!reg_dev) @@ -668,10 +678,11 @@ failure: static int call_ip6mr_vif_entry_notifiers(struct net *net, enum fib_event_type event_type, struct vif_device *vif, + struct net_device *vif_dev, mifi_t vif_index, u32 tb_id) { return mr_call_vif_notifiers(net, RTNL_FAMILY_IP6MR, event_type, - vif, vif_index, tb_id, + vif, vif_dev, vif_index, tb_id, &net->ipv6.ipmr_seq); } @@ -696,19 +707,15 @@ static int mif6_delete(struct mr_table *mrt, int vifi, int notify, v = &mrt->vif_table[vifi]; - if (VIF_EXISTS(mrt, vifi)) - call_ip6mr_vif_entry_notifiers(read_pnet(&mrt->net), - FIB_EVENT_VIF_DEL, v, vifi, - mrt->id); - - write_lock_bh(&mrt_lock); - dev = v->dev; - v->dev = NULL; - - if (!dev) { - write_unlock_bh(&mrt_lock); + dev = rtnl_dereference(v->dev); + if (!dev) return -EADDRNOTAVAIL; - } + + call_ip6mr_vif_entry_notifiers(read_pnet(&mrt->net), + FIB_EVENT_VIF_DEL, v, dev, + vifi, mrt->id); + write_lock_bh(&mrt_lock); + RCU_INIT_POINTER(v->dev, NULL); #ifdef CONFIG_IPV6_PIMSM_V2 if (vifi == mrt->mroute_reg_vif_num) @@ -911,7 +918,7 @@ static int mif6_add(struct net *net, struct mr_table *mrt, /* And finish update writing critical data */ write_lock_bh(&mrt_lock); - v->dev = dev; + rcu_assign_pointer(v->dev, dev); netdev_tracker_alloc(dev, &v->dev_tracker, GFP_ATOMIC); #ifdef CONFIG_IPV6_PIMSM_V2 if (v->flags & MIFF_REGISTER) @@ -921,7 +928,7 @@ static int mif6_add(struct net *net, struct mr_table *mrt, mrt->maxvif = vifi + 1; write_unlock_bh(&mrt_lock); call_ip6mr_vif_entry_notifiers(net, FIB_EVENT_VIF_ADD, - v, vifi, mrt->id); + v, dev, vifi, mrt->id); return 0; } @@ -1241,7 +1248,7 @@ static int ip6mr_device_event(struct notifier_block *this, ip6mr_for_each_table(mrt, net) { v = &mrt->vif_table[0]; for (ct = 0; ct < mrt->maxvif; ct++, v++) { - if (v->dev == dev) + if (rcu_access_pointer(v->dev) == dev) mif6_delete(mrt, ct, 1, NULL); } } @@ -2019,21 +2026,22 @@ static inline int ip6mr_forward2_finish(struct net *net, struct sock *sk, struct static int ip6mr_forward2(struct net *net, struct mr_table *mrt, struct sk_buff *skb, int vifi) { - struct ipv6hdr *ipv6h; struct vif_device *vif = &mrt->vif_table[vifi]; - struct net_device *dev; + struct net_device *vif_dev; + struct ipv6hdr *ipv6h; struct dst_entry *dst; struct flowi6 fl6; - if (!vif->dev) + vif_dev = vif_dev_read(vif); + if (!vif_dev) goto out_free; #ifdef CONFIG_IPV6_PIMSM_V2 if (vif->flags & MIFF_REGISTER) { vif->pkt_out++; vif->bytes_out += skb->len; - vif->dev->stats.tx_bytes += skb->len; - vif->dev->stats.tx_packets++; + vif_dev->stats.tx_bytes += skb->len; + vif_dev->stats.tx_packets++; ip6mr_cache_report(mrt, skb, vifi, MRT6MSG_WHOLEPKT); goto out_free; } @@ -2066,14 +2074,13 @@ static int ip6mr_forward2(struct net *net, struct mr_table *mrt, * not mrouter) cannot join to more than one interface - it will * result in receiving multiple packets. */ - dev = vif->dev; - skb->dev = dev; + skb->dev = vif_dev; vif->pkt_out++; vif->bytes_out += skb->len; /* We are about to write */ /* XXX: extension headers? */ - if (skb_cow(skb, sizeof(*ipv6h) + LL_RESERVED_SPACE(dev))) + if (skb_cow(skb, sizeof(*ipv6h) + LL_RESERVED_SPACE(vif_dev))) goto out_free; ipv6h = ipv6_hdr(skb); @@ -2082,7 +2089,7 @@ static int ip6mr_forward2(struct net *net, struct mr_table *mrt, IP6CB(skb)->flags |= IP6SKB_FORWARDED; return NF_HOOK(NFPROTO_IPV6, NF_INET_FORWARD, - net, NULL, skb, skb->dev, dev, + net, NULL, skb, skb->dev, vif_dev, ip6mr_forward2_finish); out_free: @@ -2095,7 +2102,7 @@ static int ip6mr_find_vif(struct mr_table *mrt, struct net_device *dev) int ct; for (ct = mrt->maxvif - 1; ct >= 0; ct--) { - if (mrt->vif_table[ct].dev == dev) + if (rcu_access_pointer(mrt->vif_table[ct].dev) == dev) break; } return ct; @@ -2133,7 +2140,7 @@ static void ip6_mr_forward(struct net *net, struct mr_table *mrt, /* * Wrong interface: drop packet and (maybe) send PIM assert. */ - if (mrt->vif_table[vif].dev != dev) { + if (rcu_access_pointer(mrt->vif_table[vif].dev) != dev) { c->_c.mfc_un.res.wrong_if++; if (true_vifi >= 0 && mrt->mroute_do_assert &&