From 4b4b84468aa27d0a18be8cb727f246aa35a3406d Mon Sep 17 00:00:00 2001 From: Taehee Yoo Date: Sun, 4 Apr 2021 13:38:23 +0000 Subject: mld: change lockdep annotation for ip6_sf_socklist and ipv6_mc_socklist struct ip6_sf_socklist and ipv6_mc_socklist are per-socket MLD data. These data are protected by rtnl lock, socket lock, and RCU. So, when these are used, it verifies whether rtnl lock is acquired or not. ip6_mc_msfget() is called by do_ipv6_getsockopt(). But caller doesn't acquire rtnl lock. So, when these data are used in the ip6_mc_msfget() lockdep warns about it. But accessing these is actually safe because socket lock was acquired by do_ipv6_getsockopt(). So, it changes lockdep annotation from rtnl lock to socket lock. (rtnl_dereference -> sock_dereference) Locking graph for mld data is like below: When writing mld data: do_ipv6_setsockopt() rtnl_lock lock_sock (mld functions) idev->mc_lock(if per-interface mld data is modified) When reading mld data: do_ipv6_getsockopt() lock_sock ip6_mc_msfget() Splat looks like: ============================= WARNING: suspicious RCU usage 5.12.0-rc4+ #503 Not tainted ----------------------------- net/ipv6/mcast.c:610 suspicious rcu_dereference_protected() usage! other info that might help us debug this: rcu_scheduler_active = 2, debug_locks = 1 1 lock held by mcast-listener-/923: #0: ffff888007958a70 (sk_lock-AF_INET6){+.+.}-{0:0}, at: ipv6_get_msfilter+0xaf/0x190 stack backtrace: CPU: 1 PID: 923 Comm: mcast-listener- Not tainted 5.12.0-rc4+ #503 Call Trace: dump_stack+0xa4/0xe5 ip6_mc_msfget+0x553/0x6c0 ? ipv6_sock_mc_join_ssm+0x10/0x10 ? lockdep_hardirqs_on_prepare+0x3e0/0x3e0 ? mark_held_locks+0xb7/0x120 ? lockdep_hardirqs_on_prepare+0x27c/0x3e0 ? __local_bh_enable_ip+0xa5/0xf0 ? lock_sock_nested+0x82/0xf0 ipv6_get_msfilter+0xc3/0x190 ? compat_ipv6_get_msfilter+0x300/0x300 ? lock_downgrade+0x690/0x690 do_ipv6_getsockopt.isra.6.constprop.13+0x1809/0x29e0 ? do_ipv6_mcast_group_source+0x150/0x150 ? register_lock_class+0x1750/0x1750 ? kvm_sched_clock_read+0x14/0x30 ? sched_clock+0x5/0x10 ? sched_clock_cpu+0x18/0x170 ? find_held_lock+0x3a/0x1c0 ? lock_downgrade+0x690/0x690 ? ipv6_getsockopt+0xdb/0x1b0 ipv6_getsockopt+0xdb/0x1b0 [ ... ] Fixes: 88e2ca308094 ("mld: convert ifmcaddr6 to RCU") Reported-by: Eric Dumazet Signed-off-by: Taehee Yoo Signed-off-by: David S. Miller --- net/ipv6/mcast.c | 48 +++++++++++++++++++++++------------------------- 1 file changed, 23 insertions(+), 25 deletions(-) (limited to 'net/ipv6/mcast.c') diff --git a/net/ipv6/mcast.c b/net/ipv6/mcast.c index 49b0cebfdcdc..ff536a158b85 100644 --- a/net/ipv6/mcast.c +++ b/net/ipv6/mcast.c @@ -114,10 +114,13 @@ int sysctl_mld_qrv __read_mostly = MLD_QRV_DEFAULT; #define mc_dereference(e, idev) \ rcu_dereference_protected(e, lockdep_is_held(&(idev)->mc_lock)) -#define for_each_pmc_rtnl(np, pmc) \ - for (pmc = rtnl_dereference((np)->ipv6_mc_list); \ +#define sock_dereference(e, sk) \ + rcu_dereference_protected(e, lockdep_sock_is_held(sk)) + +#define for_each_pmc_socklock(np, sk, pmc) \ + for (pmc = sock_dereference((np)->ipv6_mc_list, sk); \ pmc; \ - pmc = rtnl_dereference(pmc->next)) + pmc = sock_dereference(pmc->next, sk)) #define for_each_pmc_rcu(np, pmc) \ for (pmc = rcu_dereference((np)->ipv6_mc_list); \ @@ -180,7 +183,7 @@ static int __ipv6_sock_mc_join(struct sock *sk, int ifindex, if (!ipv6_addr_is_multicast(addr)) return -EINVAL; - for_each_pmc_rtnl(np, mc_lst) { + for_each_pmc_socklock(np, sk, mc_lst) { if ((ifindex == 0 || mc_lst->ifindex == ifindex) && ipv6_addr_equal(&mc_lst->addr, addr)) return -EADDRINUSE; @@ -258,7 +261,7 @@ int ipv6_sock_mc_drop(struct sock *sk, int ifindex, const struct in6_addr *addr) return -EINVAL; for (lnk = &np->ipv6_mc_list; - (mc_lst = rtnl_dereference(*lnk)) != NULL; + (mc_lst = sock_dereference(*lnk, sk)) != NULL; lnk = &mc_lst->next) { if ((ifindex == 0 || mc_lst->ifindex == ifindex) && ipv6_addr_equal(&mc_lst->addr, addr)) { @@ -323,7 +326,7 @@ void __ipv6_sock_mc_close(struct sock *sk) ASSERT_RTNL(); - while ((mc_lst = rtnl_dereference(np->ipv6_mc_list)) != NULL) { + while ((mc_lst = sock_dereference(np->ipv6_mc_list, sk)) != NULL) { struct net_device *dev; np->ipv6_mc_list = mc_lst->next; @@ -350,8 +353,11 @@ void ipv6_sock_mc_close(struct sock *sk) if (!rcu_access_pointer(np->ipv6_mc_list)) return; + rtnl_lock(); + lock_sock(sk); __ipv6_sock_mc_close(sk); + release_sock(sk); rtnl_unlock(); } @@ -381,7 +387,7 @@ int ip6_mc_source(int add, int omode, struct sock *sk, err = -EADDRNOTAVAIL; mutex_lock(&idev->mc_lock); - for_each_pmc_rtnl(inet6, pmc) { + for_each_pmc_socklock(inet6, sk, pmc) { if (pgsr->gsr_interface && pmc->ifindex != pgsr->gsr_interface) continue; if (ipv6_addr_equal(&pmc->addr, group)) @@ -404,7 +410,7 @@ int ip6_mc_source(int add, int omode, struct sock *sk, pmc->sfmode = omode; } - psl = rtnl_dereference(pmc->sflist); + psl = sock_dereference(pmc->sflist, sk); if (!add) { if (!psl) goto done; /* err = -EADDRNOTAVAIL */ @@ -511,7 +517,7 @@ int ip6_mc_msfilter(struct sock *sk, struct group_filter *gsf, goto done; } - for_each_pmc_rtnl(inet6, pmc) { + for_each_pmc_socklock(inet6, sk, pmc) { if (pmc->ifindex != gsf->gf_interface) continue; if (ipv6_addr_equal(&pmc->addr, group)) @@ -552,7 +558,7 @@ int ip6_mc_msfilter(struct sock *sk, struct group_filter *gsf, } mutex_lock(&idev->mc_lock); - psl = rtnl_dereference(pmc->sflist); + psl = sock_dereference(pmc->sflist, sk); if (psl) { ip6_mc_del_src(idev, group, pmc->sfmode, psl->sl_count, psl->sl_addr, 0); @@ -574,40 +580,32 @@ done: int ip6_mc_msfget(struct sock *sk, struct group_filter *gsf, struct sockaddr_storage __user *p) { - int err, i, count, copycount; + struct ipv6_pinfo *inet6 = inet6_sk(sk); const struct in6_addr *group; struct ipv6_mc_socklist *pmc; - struct inet6_dev *idev; - struct ipv6_pinfo *inet6 = inet6_sk(sk); struct ip6_sf_socklist *psl; - struct net *net = sock_net(sk); + int i, count, copycount; group = &((struct sockaddr_in6 *)&gsf->gf_group)->sin6_addr; if (!ipv6_addr_is_multicast(group)) return -EINVAL; - idev = ip6_mc_find_dev_rtnl(net, group, gsf->gf_interface); - if (!idev) - return -ENODEV; - - err = -EADDRNOTAVAIL; /* changes to the ipv6_mc_list require the socket lock and - * rtnl lock. We have the socket lock and rcu read lock, - * so reading the list is safe. + * rtnl lock. We have the socket lock, so reading the list is safe. */ - for_each_pmc_rtnl(inet6, pmc) { + for_each_pmc_socklock(inet6, sk, pmc) { if (pmc->ifindex != gsf->gf_interface) continue; if (ipv6_addr_equal(group, &pmc->addr)) break; } if (!pmc) /* must have a prior join */ - return err; + return -EADDRNOTAVAIL; gsf->gf_fmode = pmc->sfmode; - psl = rtnl_dereference(pmc->sflist); + psl = sock_dereference(pmc->sflist, sk); count = psl ? psl->sl_count : 0; copycount = count < gsf->gf_numsrc ? count : gsf->gf_numsrc; @@ -2600,7 +2598,7 @@ static int ip6_mc_leave_src(struct sock *sk, struct ipv6_mc_socklist *iml, struct ip6_sf_socklist *psl; int err; - psl = rtnl_dereference(iml->sflist); + psl = sock_dereference(iml->sflist, sk); if (idev) mutex_lock(&idev->mc_lock); -- cgit v1.2.3