From 7c3d825d12c5e6056ea73c0a202cbdef9d9ab9e6 Mon Sep 17 00:00:00 2001 From: Davide Caratti Date: Wed, 20 Mar 2019 15:00:12 +0100 Subject: net/sched: act_skbmod: validate the control action inside init() the following script: # tc qdisc add dev crash0 clsact # tc filter add dev crash0 egress matchall \ > action skbmod set smac 00:c1:a0:c1:a0:00 pass index 90 # tc actions replace action skbmod \ > set smac 00:c1:a0:c1:a0:00 goto chain 42 index 90 cookie c1a0c1a0 # tc actions show action skbmod had the following output: src MAC address <00:c1:a0:c1:a0:00> src MAC address <00:c1:a0:c1:a0:00> Error: Failed to init TC action chain. We have an error talking to the kernel total acts 1 action order 0: skbmod goto chain 42 set smac 00:c1:a0:c1:a0:00 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 800000002d5c7067 P4D 800000002d5c7067 PUD 77e16067 PMD 0 Oops: 0000 [#1] SMP PTI CPU: 3 PID: 0 Comm: swapper/3 Not tainted 5.0.0-rc4.gotochain_crash+ #536 Hardware name: Red Hat KVM, BIOS 0.5.1 01/01/2011 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:ffff8987ffd83be0 EFLAGS: 00010246 RAX: 000000002000002a RBX: ffff8987aeb68800 RCX: ffff8987fa263640 RDX: 0000000000000000 RSI: ffff8987f51c8802 RDI: 00000000000000a0 RBP: ffff8987ffd83c80 R08: ffff8987f939bac8 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: ffff8987f5c77d00 R13: ffff8987f5c77d08 R14: 0000000000000001 R15: ffff8987f0c29f00 FS: 0000000000000000(0000) GS:ffff8987ffd80000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000000 CR3: 000000007832c004 CR4: 00000000001606e0 Call Trace: tcf_classify+0x58/0x120 __dev_queue_xmit+0x40a/0x890 ? ip6_finish_output2+0x369/0x590 ip6_finish_output2+0x369/0x590 ? ip6_output+0x68/0x110 ip6_output+0x68/0x110 ? nf_hook.constprop.35+0x79/0xc0 mld_sendpack+0x16f/0x220 mld_ifc_timer_expire+0x195/0x2c0 ? igmp6_timer_handler+0x70/0x70 call_timer_fn+0x2b/0x130 run_timer_softirq+0x3e8/0x440 ? tick_sched_timer+0x37/0x70 __do_softirq+0xe3/0x2f5 irq_exit+0xf0/0x100 smp_apic_timer_interrupt+0x6c/0x130 apic_timer_interrupt+0xf/0x20 RIP: 0010:native_safe_halt+0x2/0x10 Code: 56 ff ff ff 7f f3 c3 65 48 8b 04 25 00 5c 01 00 f0 80 48 02 20 48 8b 00 a8 08 74 8b eb c1 90 90 90 90 90 90 90 90 90 90 fb f4 0f 1f 00 66 2e 0f 1f 84 00 00 00 00 00 f4 c3 90 90 90 90 90 90 RSP: 0018:ffffa2a1c038feb8 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13 RAX: ffffffffa94184f0 RBX: 0000000000000003 RCX: 0000000000000001 RDX: 0000000000000001 RSI: 0000000000000087 RDI: 0000000000000003 RBP: 0000000000000003 R08: 001123cfc2ba71ac R09: 0000000000000000 R10: 0000000000000000 R11: 00000000000f4240 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 ? __sched_text_end+0x1/0x1 default_idle+0x1c/0x140 do_idle+0x1c4/0x280 cpu_startup_entry+0x19/0x20 start_secondary+0x1a7/0x200 secondary_startup_64+0xa4/0xb0 Modules linked in: act_skbmod veth ip6table_filter ip6_tables iptable_filter binfmt_misc ext4 crct10dif_pclmul crc32_pclmul ghash_clmulni_intel mbcache jbd2 snd_hda_codec_generic snd_hda_intel snd_hda_codec snd_hwdep snd_hda_core snd_seq snd_seq_device aesni_intel crypto_simd cryptd glue_helper snd_pcm joydev pcspkr virtio_balloon snd_timer snd i2c_piix4 soundcore nfsd auth_rpcgss nfs_acl lockd grace sunrpc ip_tables xfs ata_generic pata_acpi qxl drm_kms_helper syscopyarea sysfillrect virtio_net sysimgblt fb_sys_fops net_failover virtio_console ttm virtio_blk failover drm crc32c_intel serio_raw ata_piix virtio_pci libata virtio_ring virtio floppy dm_mirror dm_region_hash dm_log dm_mod CR2: 0000000000000000 Validating the control action within tcf_skbmod_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_skbmod.c | 19 ++++++++++++++++--- 1 file changed, 16 insertions(+), 3 deletions(-) (limited to 'net/sched') diff --git a/net/sched/act_skbmod.c b/net/sched/act_skbmod.c index b9ab2c8f07f1..1d4c324d0a42 100644 --- a/net/sched/act_skbmod.c +++ b/net/sched/act_skbmod.c @@ -16,6 +16,7 @@ #include #include #include +#include #include #include @@ -88,6 +89,7 @@ static int tcf_skbmod_init(struct net *net, struct nlattr *nla, struct tc_action_net *tn = net_generic(net, skbmod_net_id); struct nlattr *tb[TCA_SKBMOD_MAX + 1]; struct tcf_skbmod_params *p, *p_old; + struct tcf_chain *goto_ch = NULL; struct tc_skbmod *parm; struct tcf_skbmod *d; bool exists = false; @@ -154,21 +156,24 @@ static int tcf_skbmod_init(struct net *net, struct nlattr *nla, tcf_idr_release(*a, bind); return -EEXIST; } + err = tcf_action_check_ctrlact(parm->action, tp, &goto_ch, extack); + if (err < 0) + goto release_idr; d = to_skbmod(*a); p = kzalloc(sizeof(struct tcf_skbmod_params), GFP_KERNEL); if (unlikely(!p)) { - tcf_idr_release(*a, bind); - return -ENOMEM; + err = -ENOMEM; + goto put_chain; } p->flags = lflags; - d->tcf_action = parm->action; if (ovr) spin_lock_bh(&d->tcf_lock); /* Protected by tcf_lock if overwriting existing action. */ + goto_ch = tcf_action_set_ctrlact(*a, parm->action, goto_ch); p_old = rcu_dereference_protected(d->skbmod_p, 1); if (lflags & SKBMOD_F_DMAC) @@ -184,10 +189,18 @@ static int tcf_skbmod_init(struct net *net, struct nlattr *nla, if (p_old) kfree_rcu(p_old, 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 void tcf_skbmod_cleanup(struct tc_action *a) -- cgit v1.2.3