From ec7727bb24b01e96b0c46068addf355ee4f794d8 Mon Sep 17 00:00:00 2001 From: Davide Caratti Date: Wed, 20 Mar 2019 15:00:11 +0100 Subject: [PATCH] net/sched: act_skbedit: validate the control action inside init() the following script: # tc qdisc add dev crash0 clsact # tc filter add dev crash0 egress matchall \ > action skbedit ptype host pass index 90 # tc actions replace action skbedit \ > ptype host goto chain 42 index 90 cookie c1a0c1a0 # tc actions show action skbedit 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: skbedit ptype host goto chain 42 index 90 ref 2 bind 1 cookie c1a0c1a0 Then, the first packet transmitted by crash0 made the kernel crash: 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: 3467 Comm: kworker/3:3 Not tainted 5.0.0-rc4.gotochain_crash+ #536 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:ffffb50a81e1fad0 EFLAGS: 00010246 RAX: 000000002000002a RBX: ffff9aa47ba4ea00 RCX: 0000000000000001 RDX: 0000000000000000 RSI: ffff9aa469eeb3c0 RDI: ffff9aa47ba4ea00 RBP: ffffb50a81e1fb70 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: ffff9aa47bce0638 R12: ffff9aa4793b0c00 R13: ffff9aa4793b0c08 R14: 0000000000000001 R15: ffff9aa469eeb3c0 FS: 0000000000000000(0000) GS:ffff9aa474780000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000000 CR3: 000000007360e005 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_skbedit veth ip6table_filter ip6_tables iptable_filter binfmt_misc crct10dif_pclmul crc32_pclmul ghash_clmulni_intel ext4 snd_hda_codec_generic snd_hda_intel snd_hda_codec snd_hwdep mbcache snd_hda_core jbd2 snd_seq snd_seq_device snd_pcm aesni_intel crypto_simd cryptd snd_timer glue_helper snd joydev soundcore pcspkr virtio_balloon 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 ttm virtio_net net_failover drm failover virtio_blk virtio_console ata_piix virtio_pci crc32c_intel serio_raw libata virtio_ring virtio floppy dm_mirror dm_region_hash dm_log dm_mod CR2: 0000000000000000 Validating the control action within tcf_skbedit_init() proved to fix the above issue. 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 Signed-off-by: David S. Miller --- net/sched/act_skbedit.c | 19 +++++++++++--- .../tc-testing/tc-tests/actions/skbedit.json | 25 +++++++++++++++++++ 2 files changed, 41 insertions(+), 3 deletions(-) diff --git a/net/sched/act_skbedit.c b/net/sched/act_skbedit.c index 4566eff3d027..7e1d261a31d2 100644 --- a/net/sched/act_skbedit.c +++ b/net/sched/act_skbedit.c @@ -26,6 +26,7 @@ #include #include #include +#include #include #include @@ -102,6 +103,7 @@ static int tcf_skbedit_init(struct net *net, struct nlattr *nla, struct tc_action_net *tn = net_generic(net, skbedit_net_id); struct tcf_skbedit_params *params_new; struct nlattr *tb[TCA_SKBEDIT_MAX + 1]; + struct tcf_chain *goto_ch = NULL; struct tc_skbedit *parm; struct tcf_skbedit *d; u32 flags = 0, *priority = NULL, *mark = NULL, *mask = NULL; @@ -187,11 +189,14 @@ static int tcf_skbedit_init(struct net *net, struct nlattr *nla, return -EEXIST; } } + err = tcf_action_check_ctrlact(parm->action, tp, &goto_ch, extack); + if (err < 0) + goto release_idr; params_new = kzalloc(sizeof(*params_new), GFP_KERNEL); if (unlikely(!params_new)) { - tcf_idr_release(*a, bind); - return -ENOMEM; + err = -ENOMEM; + goto put_chain; } params_new->flags = flags; @@ -209,16 +214,24 @@ static int tcf_skbedit_init(struct net *net, struct nlattr *nla, params_new->mask = *mask; spin_lock_bh(&d->tcf_lock); - d->tcf_action = parm->action; + goto_ch = tcf_action_set_ctrlact(*a, parm->action, goto_ch); rcu_swap_protected(d->params, params_new, lockdep_is_held(&d->tcf_lock)); spin_unlock_bh(&d->tcf_lock); if (params_new) kfree_rcu(params_new, rcu); + if (goto_ch) + tcf_chain_put_by_act(goto_ch); if (ret == ACT_P_CREATED) tcf_idr_insert(tn, *a); return ret; +put_chain: + if (goto_ch) + tcf_chain_put_by_act(goto_ch); +release_idr: + tcf_idr_release(*a, bind); + return err; } static int tcf_skbedit_dump(struct sk_buff *skb, struct tc_action *a, diff --git a/tools/testing/selftests/tc-testing/tc-tests/actions/skbedit.json b/tools/testing/selftests/tc-testing/tc-tests/actions/skbedit.json index 5aaf593b914a..ecd96eda7f6a 100644 --- a/tools/testing/selftests/tc-testing/tc-tests/actions/skbedit.json +++ b/tools/testing/selftests/tc-testing/tc-tests/actions/skbedit.json @@ -484,5 +484,30 @@ "teardown": [ "$TC actions flush action skbedit" ] + }, + { + "id": "1b2b", + "name": "Replace skbedit action with invalid goto_chain control", + "category": [ + "actions", + "skbedit" + ], + "setup": [ + [ + "$TC actions flush action skbedit", + 0, + 1, + 255 + ], + "$TC actions add action skbedit ptype host pass index 90" + ], + "cmdUnderTest": "$TC actions replace action skbedit ptype host goto chain 42 index 90 cookie c1a0c1a0", + "expExitCode": "255", + "verifyCmd": "$TC actions list action skbedit", + "matchPattern": "action order [0-9]*: skbedit ptype host pass.*index 90 ref", + "matchCount": "1", + "teardown": [ + "$TC actions flush action skbedit" + ] } ] -- 2.30.2