From d974719415d5ccad3ff787dd4803d8cfad8bed4d Mon Sep 17 00:00:00 2001 From: Davide Caratti Date: Wed, 27 Feb 2019 18:40:34 +0100 Subject: [PATCH] net/sched: act_mirred: validate the control action inside init() the following script: # tc qdisc add dev crash0 clsact # tc filter add dev crash0 egress matchall \ > action mirred ingress mirror dev lo pass # tc actions replace action mirred \ > ingress mirror dev lo goto chain 42 index 90 cookie c1a0c1a0 # tc actions show action mirred had the following output: Error: Failed to init TC action chain. We have an error talking to the kernel total acts 1 action order 0: mirred (Ingress Mirror to device lo) goto chain 42 index 90 ref 2 bind 1 cookie c1a0c1a0 Then, the first packet transmitted by crash0 made the kernel crash: Mirror/redirect action on BUG: unable to handle kernel NULL pointer dereference at 0000000000000000 #PF error: [normal kernel read fault] PGD 0 P4D 0 Oops: 0000 [#1] SMP PTI CPU: 3 PID: 47 Comm: kworker/3:1 Not tainted 5.0.0-rc4.gotochain_crash+ #533 Hardware name: Red Hat KVM, BIOS 0.5.1 01/01/2011 Workqueue: ipv6_addrconf addrconf_dad_work RIP: 0010:tcf_action_exec+0xb8/0x100 Code: 00 00 00 20 74 1d 83 f8 03 75 09 49 83 c4 08 4d 39 ec 75 bc 48 83 c4 10 5b 5d 41 5c 41 5d 41 5e 41 5f c3 49 8b 97 a8 00 00 00 <48> 8b 12 48 89 55 00 48 83 c4 10 5b 5d 41 5c 41 5d 41 5e 41 5f c3 RSP: 0018:ffffa772404b7ad0 EFLAGS: 00010246 RAX: 000000002000002a RBX: ffff9c5afc3f4300 RCX: 0000000000000000 RDX: 0000000000000000 RSI: ffff9c5afdba9380 RDI: 0000000000029380 RBP: ffffa772404b7b70 R08: ffff9c5af7010028 R09: ffff9c5af7010029 R10: 0000000000000000 R11: ffff9c5af94c6a38 R12: ffff9c5af7953000 R13: ffff9c5af7953008 R14: 0000000000000001 R15: ffff9c5af7953d00 FS: 0000000000000000(0000) GS:ffff9c5afdb80000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000000 CR3: 000000007c514004 CR4: 00000000001606e0 Call Trace: tcf_classify+0x58/0x120 __dev_queue_xmit+0x40a/0x890 ? ndisc_next_option+0x50/0x50 ? ___neigh_create+0x4d5/0x680 ? ip6_finish_output2+0x1b5/0x590 ip6_finish_output2+0x1b5/0x590 ? ip6_output+0x68/0x110 ip6_output+0x68/0x110 ? nf_hook.constprop.28+0x79/0xc0 ndisc_send_skb+0x248/0x2e0 ndisc_send_ns+0xf8/0x200 ? addrconf_dad_work+0x389/0x4b0 addrconf_dad_work+0x389/0x4b0 ? __switch_to_asm+0x34/0x70 ? process_one_work+0x195/0x380 ? addrconf_dad_completed+0x370/0x370 process_one_work+0x195/0x380 worker_thread+0x30/0x390 ? process_one_work+0x380/0x380 kthread+0x113/0x130 ? kthread_park+0x90/0x90 ret_from_fork+0x35/0x40 Modules linked in: act_mirred veth ip6table_filter ip6_tables iptable_filter binfmt_misc ext4 crct10dif_pclmul snd_hda_codec_generic crc32_pclmul snd_hda_intel snd_hda_codec mbcache ghash_clmulni_intel jbd2 snd_hwdep snd_hda_core snd_seq snd_seq_device snd_pcm aesni_intel snd_timer snd crypto_simd cryptd glue_helper soundcore virtio_balloon joydev pcspkr i2c_piix4 nfsd auth_rpcgss nfs_acl lockd grace sunrpc ip_tables xfs ata_generic pata_acpi qxl drm_kms_helper syscopyarea sysfillrect sysimgblt fb_sys_fops virtio_net ttm virtio_blk net_failover virtio_console failover drm ata_piix crc32c_intel virtio_pci serio_raw libata virtio_ring virtio floppy dm_mirror dm_region_hash dm_log dm_mod CR2: 0000000000000000 Validating the control action within tcf_mirred_init() proved to fix the above issue. For the same reason, postpone the assignment of tcfa_action and tcfm_eaction to avoid partial reconfiguration of a mirred rule when it's replaced by another one that mirrors to a device that does not exist. A TDC selftest is added to verify the correct behavior. Fixes: db50514f9a9c ("net: sched: add termination action to allow goto chain") Fixes: 97763dc0f401 ("net_sched: reject unknown tcfa_action values") Signed-off-by: Davide Caratti --- net/sched/act_mirred.c | 23 ++++++++++++++--- .../tc-testing/tc-tests/actions/mirred.json | 25 +++++++++++++++++++ 2 files changed, 44 insertions(+), 4 deletions(-) diff --git a/net/sched/act_mirred.c b/net/sched/act_mirred.c index 69dda57f1097d0..49f5116d01e690 100644 --- a/net/sched/act_mirred.c +++ b/net/sched/act_mirred.c @@ -99,6 +99,7 @@ static int tcf_mirred_init(struct net *net, struct nlattr *nla, { struct tc_action_net *tn = net_generic(net, mirred_net_id); struct nlattr *tb[TCA_MIRRED_MAX + 1]; + struct tcf_chain *newchain = NULL, *oldchain; bool mac_header_xmit = false; struct tc_mirred *parm; struct tcf_mirred *m; @@ -158,18 +159,20 @@ static int tcf_mirred_init(struct net *net, struct nlattr *nla, tcf_idr_release(*a, bind); return -EEXIST; } + err = tcf_action_check_ctrlact(parm->action, tp, &newchain, extack); + if (err) + goto release_idr; + m = to_mirred(*a); spin_lock_bh(&m->tcf_lock); - m->tcf_action = parm->action; - m->tcfm_eaction = parm->eaction; if (parm->ifindex) { dev = dev_get_by_index(net, parm->ifindex); if (!dev) { spin_unlock_bh(&m->tcf_lock); - tcf_idr_release(*a, bind); - return -ENODEV; + err = -ENODEV; + goto put_chain; } mac_header_xmit = dev_is_mac_header_xmit(dev); rcu_swap_protected(m->tcfm_dev, dev, @@ -178,6 +181,10 @@ static int tcf_mirred_init(struct net *net, struct nlattr *nla, dev_put(dev); m->tcfm_mac_header_xmit = mac_header_xmit; } + oldchain = m->tcf_goto_chain; + m->tcf_goto_chain = newchain; + m->tcf_action = parm->action; + m->tcfm_eaction = parm->eaction; spin_unlock_bh(&m->tcf_lock); if (ret == ACT_P_CREATED) { @@ -188,7 +195,15 @@ static int tcf_mirred_init(struct net *net, struct nlattr *nla, tcf_idr_insert(tn, *a); } + if (oldchain) + tcf_chain_put_by_act(oldchain); return ret; +put_chain: + if (newchain) + tcf_chain_put_by_act(newchain); +release_idr: + tcf_idr_release(*a, bind); + return err; } static int tcf_mirred_act(struct sk_buff *skb, const struct tc_action *a, diff --git a/tools/testing/selftests/tc-testing/tc-tests/actions/mirred.json b/tools/testing/selftests/tc-testing/tc-tests/actions/mirred.json index db49fd0f84459f..6e5fb3d256811a 100644 --- a/tools/testing/selftests/tc-testing/tc-tests/actions/mirred.json +++ b/tools/testing/selftests/tc-testing/tc-tests/actions/mirred.json @@ -434,5 +434,30 @@ "teardown": [ "$TC actions flush action mirred" ] + }, + { + "id": "2a9a", + "name": "Replace mirred action with invalid goto chain control", + "category": [ + "actions", + "mirred" + ], + "setup": [ + [ + "$TC actions flush action mirred", + 0, + 1, + 255 + ], + "$TC actions add action mirred ingress mirror dev lo drop index 90" + ], + "cmdUnderTest": "$TC actions replace action mirred ingress mirror dev lo goto chain 42 index 90 cookie c1a0c1a0", + "expExitCode": "255", + "verifyCmd": "$TC actions get action mirred index 90", + "matchPattern": "action order [0-9]*: mirred \\(Ingress Mirror to device lo\\) drop.*index 90 ref", + "matchCount": "1", + "teardown": [ + "$TC actions flush action mirred" + ] } ]