kernel.git/net/l2tp, branch linux-5.4.y

genetlink: hold RCU in genlmsg_mcast()

2024-11-08T15:20:50Z

[ Upstream commit 56440d7ec28d60f8da3bfa09062b3368ff9b16db ] While running net selftests with CONFIG_PROVE_RCU_LIST=y I saw one lockdep splat [1]. genlmsg_mcast() uses for_each_net_rcu(), and must therefore hold RCU. Instead of letting all callers guard genlmsg_multicast_allns() with a rcu_read_lock()/rcu_read_unlock() pair, do it in genlmsg_mcast(). This also means the @flags parameter is useless, we need to always use GFP_ATOMIC. [1] [10882.424136] ============================= [10882.424166] WARNING: suspicious RCU usage [10882.424309] 6.12.0-rc2-virtme #1156 Not tainted [10882.424400] ----------------------------- [10882.424423] net/netlink/genetlink.c:1940 RCU-list traversed in non-reader section!! [10882.424469] other info that might help us debug this: [10882.424500] rcu_scheduler_active = 2, debug_locks = 1 [10882.424744] 2 locks held by ip/15677: [10882.424791] #0: ffffffffb6b491b0 (cb_lock){++++}-{3:3}, at: genl_rcv (net/netlink/genetlink.c:1219) [10882.426334] #1: ffffffffb6b49248 (genl_mutex){+.+.}-{3:3}, at: genl_rcv_msg (net/netlink/genetlink.c:61 net/netlink/genetlink.c:57 net/netlink/genetlink.c:1209) [10882.426465] stack backtrace: [10882.426805] CPU: 14 UID: 0 PID: 15677 Comm: ip Not tainted 6.12.0-rc2-virtme #1156 [10882.426919] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 [10882.427046] Call Trace: [10882.427131] [10882.427244] dump_stack_lvl (lib/dump_stack.c:123) [10882.427335] lockdep_rcu_suspicious (kernel/locking/lockdep.c:6822) [10882.427387] genlmsg_multicast_allns (net/netlink/genetlink.c:1940 (discriminator 7) net/netlink/genetlink.c:1977 (discriminator 7)) [10882.427436] l2tp_tunnel_notify.constprop.0 (net/l2tp/l2tp_netlink.c:119) l2tp_netlink [10882.427683] l2tp_nl_cmd_tunnel_create (net/l2tp/l2tp_netlink.c:253) l2tp_netlink [10882.427748] genl_family_rcv_msg_doit (net/netlink/genetlink.c:1115) [10882.427834] genl_rcv_msg (net/netlink/genetlink.c:1195 net/netlink/genetlink.c:1210) [10882.427877] ? __pfx_l2tp_nl_cmd_tunnel_create (net/l2tp/l2tp_netlink.c:186) l2tp_netlink [10882.427927] ? __pfx_genl_rcv_msg (net/netlink/genetlink.c:1201) [10882.427959] netlink_rcv_skb (net/netlink/af_netlink.c:2551) [10882.428069] genl_rcv (net/netlink/genetlink.c:1220) [10882.428095] netlink_unicast (net/netlink/af_netlink.c:1332 net/netlink/af_netlink.c:1357) [10882.428140] netlink_sendmsg (net/netlink/af_netlink.c:1901) [10882.428210] ____sys_sendmsg (net/socket.c:729 (discriminator 1) net/socket.c:744 (discriminator 1) net/socket.c:2607 (discriminator 1)) Fixes: 33f72e6f0c67 ("l2tp : multicast notification to the registered listeners") Signed-off-by: Eric Dumazet Cc: James Chapman Cc: Tom Parkin Cc: Johannes Berg Link: https://patch.msgid.link/20241011171217.3166614-1-edumazet@google.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

net l2tp: drop flow hash on forward

2024-05-17T09:43:49Z

[ Upstream commit 42f853b42899d9b445763b55c3c8adc72be0f0e1 ] Drop the flow-hash of the skb when forwarding to the L2TP netdev. This avoids the L2TP qdisc from using the flow-hash from the outer packet, which is identical for every flow within the tunnel. This does not affect every platform but is specific for the ethernet driver. It depends on the platform including L4 information in the flow-hash. One such example is the Mediatek Filogic MT798x family of networking processors. Fixes: d9e31d17ceba ("l2tp: Add L2TP ethernet pseudowire support") Acked-by: James Chapman Signed-off-by: David Bauer Reviewed-by: Simon Horman Link: https://lore.kernel.org/r/20240424171110.13701-1-mail@david-bauer.net Signed-off-by: Paolo Abeni Signed-off-by: Sasha Levin

l2tp: fix incorrect parameter validation in the pppol2tp_getsockopt() function

2024-03-26T22:22:17Z

[ Upstream commit 955e9876ba4ee26eeaab1b13517f5b2c88e73d55 ] The 'len' variable can't be negative when assigned the result of 'min_t' because all 'min_t' parameters are cast to unsigned int, and then the minimum one is chosen. To fix the logic, check 'len' as read from 'optlen', where the types of relevant variables are (signed) int. Fixes: 3557baabf280 ("[L2TP]: PPP over L2TP driver core") Reviewed-by: Tom Parkin Signed-off-by: Gavrilov Ilia Signed-off-by: David S. Miller Signed-off-by: Sasha Levin

l2tp: pass correct message length to ip6_append_data

2024-03-01T12:13:36Z

commit 359e54a93ab43d32ee1bff3c2f9f10cb9f6b6e79 upstream. l2tp_ip6_sendmsg needs to avoid accounting for the transport header twice when splicing more data into an already partially-occupied skbuff. To manage this, we check whether the skbuff contains data using skb_queue_empty when deciding how much data to append using ip6_append_data. However, the code which performed the calculation was incorrect: ulen = len + skb_queue_empty(&sk->sk_write_queue) ? transhdrlen : 0; ...due to C operator precedence, this ends up setting ulen to transhdrlen for messages with a non-zero length, which results in corrupted packets on the wire. Add parentheses to correct the calculation in line with the original intent. Fixes: 9d4c75800f61 ("ipv4, ipv6: Fix handling of transhdrlen in __ip{,6}_append_data()") Cc: David Howells Cc: stable@vger.kernel.org Signed-off-by: Tom Parkin Reviewed-by: Simon Horman Link: https://lore.kernel.org/r/20240220122156.43131-1-tparkin@katalix.com Signed-off-by: Paolo Abeni Signed-off-by: Greg Kroah-Hartman

ipv4, ipv6: Fix handling of transhdrlen in __ip{,6}_append_data()

2023-10-10T19:46:44Z

[ Upstream commit 9d4c75800f61e5d75c1659ba201b6c0c7ead3070 ] Including the transhdrlen in length is a problem when the packet is partially filled (e.g. something like send(MSG_MORE) happened previously) when appending to an IPv4 or IPv6 packet as we don't want to repeat the transport header or account for it twice. This can happen under some circumstances, such as splicing into an L2TP socket. The symptom observed is a warning in __ip6_append_data(): WARNING: CPU: 1 PID: 5042 at net/ipv6/ip6_output.c:1800 __ip6_append_data.isra.0+0x1be8/0x47f0 net/ipv6/ip6_output.c:1800 that occurs when MSG_SPLICE_PAGES is used to append more data to an already partially occupied skbuff. The warning occurs when 'copy' is larger than the amount of data in the message iterator. This is because the requested length includes the transport header length when it shouldn't. This can be triggered by, for example: sfd = socket(AF_INET6, SOCK_DGRAM, IPPROTO_L2TP); bind(sfd, ...); // ::1 connect(sfd, ...); // ::1 port 7 send(sfd, buffer, 4100, MSG_MORE); sendfile(sfd, dfd, NULL, 1024); Fix this by only adding transhdrlen into the length if the write queue is empty in l2tp_ip6_sendmsg(), analogously to how UDP does things. l2tp_ip_sendmsg() looks like it won't suffer from this problem as it builds the UDP packet itself. Fixes: a32e0eec7042 ("l2tp: introduce L2TPv3 IP encapsulation support for IPv6") Reported-by: syzbot+62cbf263225ae13ff153@syzkaller.appspotmail.com Link: https://lore.kernel.org/r/0000000000001c12b30605378ce8@google.com/ Suggested-by: Willem de Bruijn Signed-off-by: David Howells cc: Eric Dumazet cc: Willem de Bruijn cc: "David S. Miller" cc: David Ahern cc: Paolo Abeni cc: Jakub Kicinski cc: netdev@vger.kernel.org cc: bpf@vger.kernel.org cc: syzkaller-bugs@googlegroups.com Reviewed-by: Eric Dumazet Signed-off-by: David S. Miller Signed-off-by: Sasha Levin

inet6: Remove inet6_destroy_sock() in sk->sk_prot->destroy().

2023-04-26T09:24:05Z

commit b5fc29233d28be7a3322848ebe73ac327559cdb9 upstream. After commit d38afeec26ed ("tcp/udp: Call inet6_destroy_sock() in IPv6 sk->sk_destruct()."), we call inet6_destroy_sock() in sk->sk_destruct() by setting inet6_sock_destruct() to it to make sure we do not leak inet6-specific resources. Now we can remove unnecessary inet6_destroy_sock() calls in sk->sk_prot->destroy(). DCCP and SCTP have their own sk->sk_destruct() function, so we change them separately in the following patches. Signed-off-by: Kuniyuki Iwashima Reviewed-by: Matthieu Baerts Signed-off-by: David S. Miller Signed-off-by: Ziyang Xuan Signed-off-by: Greg Kroah-Hartman

l2tp: Don't sleep and disable BH under writer-side sk_callback_lock

2023-02-06T06:52:38Z

[ Upstream commit af295e854a4e3813ffbdef26dbb6a4d6226c3ea1 ] When holding a reader-writer spin lock we cannot sleep. Calling setup_udp_tunnel_sock() with write lock held violates this rule, because we end up calling percpu_down_read(), which might sleep, as syzbot reports [1]: __might_resched.cold+0x222/0x26b kernel/sched/core.c:9890 percpu_down_read include/linux/percpu-rwsem.h:49 [inline] cpus_read_lock+0x1b/0x140 kernel/cpu.c:310 static_key_slow_inc+0x12/0x20 kernel/jump_label.c:158 udp_tunnel_encap_enable include/net/udp_tunnel.h:187 [inline] setup_udp_tunnel_sock+0x43d/0x550 net/ipv4/udp_tunnel_core.c:81 l2tp_tunnel_register+0xc51/0x1210 net/l2tp/l2tp_core.c:1509 pppol2tp_connect+0xcdc/0x1a10 net/l2tp/l2tp_ppp.c:723 Trim the writer-side critical section for sk_callback_lock down to the minimum, so that it covers only operations on sk_user_data. Also, when grabbing the sk_callback_lock, we always need to disable BH, as Eric points out. Failing to do so leads to deadlocks because we acquire sk_callback_lock in softirq context, which can get stuck waiting on us if: 1) it runs on the same CPU, or CPU0 ---- lock(clock-AF_INET6); lock(clock-AF_INET6); 2) lock ordering leads to priority inversion CPU0 CPU1 ---- ---- lock(clock-AF_INET6); local_irq_disable(); lock(&tcp_hashinfo.bhash[i].lock); lock(clock-AF_INET6); lock(&tcp_hashinfo.bhash[i].lock); ... as syzbot reports [2,3]. Use the _bh variants for write_(un)lock. [1] https://lore.kernel.org/netdev/0000000000004e78ec05eda79749@google.com/ [2] https://lore.kernel.org/netdev/000000000000e38b6605eda76f98@google.com/ [3] https://lore.kernel.org/netdev/000000000000dfa31e05eda76f75@google.com/ v2: - Check and set sk_user_data while holding sk_callback_lock for both L2TP encapsulation types (IP and UDP) (Tetsuo) Cc: Tom Parkin Cc: Tetsuo Handa Fixes: b68777d54fac ("l2tp: Serialize access to sk_user_data with sk_callback_lock") Reported-by: Eric Dumazet Reported-by: syzbot+703d9e154b3b58277261@syzkaller.appspotmail.com Reported-by: syzbot+50680ced9e98a61f7698@syzkaller.appspotmail.com Reported-by: syzbot+de987172bb74a381879b@syzkaller.appspotmail.com Signed-off-by: Jakub Sitnicki Signed-off-by: David S. Miller Signed-off-by: Sasha Levin

l2tp: Serialize access to sk_user_data with sk_callback_lock

2023-02-06T06:52:37Z

[ Upstream commit b68777d54fac21fc833ec26ea1a2a84f975ab035 ] sk->sk_user_data has multiple users, which are not compatible with each other. Writers must synchronize by grabbing the sk->sk_callback_lock. l2tp currently fails to grab the lock when modifying the underlying tunnel socket fields. Fix it by adding appropriate locking. We err on the side of safety and grab the sk_callback_lock also inside the sk_destruct callback overridden by l2tp, even though there should be no refs allowing access to the sock at the time when sk_destruct gets called. v4: - serialize write to sk_user_data in l2tp sk_destruct v3: - switch from sock lock to sk_callback_lock - document write-protection for sk_user_data v2: - update Fixes to point to origin of the bug - use real names in Reported/Tested-by tags Cc: Tom Parkin Fixes: 3557baabf280 ("[L2TP]: PPP over L2TP driver core") Reported-by: Haowei Yan Signed-off-by: Jakub Sitnicki Signed-off-by: David S. Miller Signed-off-by: Sasha Levin

net: fix a concurrency bug in l2tp_tunnel_register()

2023-02-06T06:52:37Z

[ Upstream commit 69e16d01d1de4f1249869de342915f608feb55d5 ] l2tp_tunnel_register() registers a tunnel without fully initializing its attribute. This can allow another kernel thread running l2tp_xmit_core() to access the uninitialized data and then cause a kernel NULL pointer dereference error, as shown below. Thread 1 Thread 2 //l2tp_tunnel_register() list_add_rcu(&tunnel->list, &pn->l2tp_tunnel_list); //pppol2tp_connect() tunnel = l2tp_tunnel_get(sock_net(sk), info.tunnel_id); // Fetch the new tunnel ... //l2tp_xmit_core() struct sock *sk = tunnel->sock; ... bh_lock_sock(sk); //Null pointer error happens tunnel->sock = sk; Fix this bug by initializing tunnel->sock before adding the tunnel into l2tp_tunnel_list. Reviewed-by: Cong Wang Signed-off-by: Sishuai Gong Reported-by: Sishuai Gong Signed-off-by: David S. Miller Signed-off-by: Sasha Levin

ipv6: Fix signed integer overflow in l2tp_ip6_sendmsg

2022-06-22T12:11:21Z

[ Upstream commit f638a84afef3dfe10554c51820c16e39a278c915 ] When len >= INT_MAX - transhdrlen, ulen = len + transhdrlen will be overflow. To fix, we can follow what udpv6 does and subtract the transhdrlen from the max. Signed-off-by: Wang Yufen Link: https://lore.kernel.org/r/20220607120028.845916-2-wangyufen@huawei.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin