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 <dcaratti@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/sched/act_mirred.c b/net/sched/act_mirred.c
index 383f402..cd712e4 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 *goto_ch = NULL;
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, &goto_ch, extack);
+ if (err < 0)
+ 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,
@@ -178,7 +181,11 @@ static int tcf_mirred_init(struct net *net, struct nlattr *nla,
dev_put(dev);
m->tcfm_mac_header_xmit = mac_header_xmit;
}
+ goto_ch = tcf_action_set_ctrlact(*a, parm->action, goto_ch);
+ m->tcfm_eaction = parm->eaction;
spin_unlock_bh(&m->tcf_lock);
+ if (goto_ch)
+ tcf_chain_put_by_act(goto_ch);
if (ret == ACT_P_CREATED) {
spin_lock(&mirred_list_lock);
@@ -189,6 +196,12 @@ static int tcf_mirred_init(struct net *net, struct nlattr *nla,
}
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_mirred_act(struct sk_buff *skb, const struct tc_action *a,
