![Davide Caratti](/assets/img/avatar_default.png)
the following script: # tc qdisc add dev crash0 clsact # tc filter add dev crash0 egress matchall \ > action sample rate 1024 group 4 pass index 90 # tc actions replace action sample \ > rate 1024 group 4 goto chain 42 index 90 cookie c1a0c1a0 # tc actions show action sample 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: sample rate 1/1024 group 4 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 8000000079966067 P4D 8000000079966067 PUD 7987b067 PMD 0 Oops: 0000 [#1] SMP PTI CPU: 0 PID: 5 Comm: kworker/0:0 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:ffffbee60033fad0 EFLAGS: 00010246 RAX: 000000002000002a RBX: ffff99d7ae6e3b00 RCX: 00000000e555df9b RDX: 0000000000000000 RSI: 00000000b0352718 RDI: ffff99d7fda1fcf0 RBP: ffffbee60033fb70 R08: 0000000070731ab1 R09: 0000000000000400 R10: 0000000000000000 R11: ffff99d7ac733838 R12: ffff99d7f3c2be00 R13: ffff99d7f3c2be08 R14: 0000000000000001 R15: ffff99d7f3c2b600 FS: 0000000000000000(0000) GS:ffff99d7fda00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000000 CR3: 00000000797de006 CR4: 00000000001606f0 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_sample psample 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 snd_pcm cryptd glue_helper snd_timer joydev snd pcspkr virtio_balloon 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 ttm failover virtio_blk virtio_console drm ata_piix serio_raw crc32c_intel libata virtio_pci virtio_ring virtio floppy dm_mirror dm_region_hash dm_log dm_mod CR2: 0000000000000000 Validating the control action within tcf_sample_init() proved to fix the above issue. A TDC selftest is added to verify the correct behavior. Fixes:db50514f9a
("net: sched: add termination action to allow goto chain") Fixes:97763dc0f4
("net_sched: reject unknown tcfa_action values") Signed-off-by: Davide Caratti <dcaratti@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
295 lines
7.5 KiB
C
295 lines
7.5 KiB
C
/*
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* net/sched/act_sample.c - Packet sampling tc action
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* Copyright (c) 2017 Yotam Gigi <yotamg@mellanox.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/types.h>
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#include <linux/kernel.h>
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#include <linux/string.h>
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#include <linux/errno.h>
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#include <linux/skbuff.h>
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#include <linux/rtnetlink.h>
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#include <linux/module.h>
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#include <linux/init.h>
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#include <linux/gfp.h>
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#include <net/net_namespace.h>
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#include <net/netlink.h>
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#include <net/pkt_sched.h>
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#include <linux/tc_act/tc_sample.h>
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#include <net/tc_act/tc_sample.h>
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#include <net/psample.h>
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#include <net/pkt_cls.h>
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#include <linux/if_arp.h>
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static unsigned int sample_net_id;
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static struct tc_action_ops act_sample_ops;
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static const struct nla_policy sample_policy[TCA_SAMPLE_MAX + 1] = {
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[TCA_SAMPLE_PARMS] = { .len = sizeof(struct tc_sample) },
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[TCA_SAMPLE_RATE] = { .type = NLA_U32 },
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[TCA_SAMPLE_TRUNC_SIZE] = { .type = NLA_U32 },
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[TCA_SAMPLE_PSAMPLE_GROUP] = { .type = NLA_U32 },
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};
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static int tcf_sample_init(struct net *net, struct nlattr *nla,
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struct nlattr *est, struct tc_action **a, int ovr,
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int bind, bool rtnl_held, struct tcf_proto *tp,
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struct netlink_ext_ack *extack)
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{
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struct tc_action_net *tn = net_generic(net, sample_net_id);
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struct nlattr *tb[TCA_SAMPLE_MAX + 1];
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struct psample_group *psample_group;
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struct tcf_chain *goto_ch = NULL;
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struct tc_sample *parm;
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u32 psample_group_num;
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struct tcf_sample *s;
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bool exists = false;
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int ret, err;
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if (!nla)
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return -EINVAL;
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ret = nla_parse_nested(tb, TCA_SAMPLE_MAX, nla, sample_policy, NULL);
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if (ret < 0)
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return ret;
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if (!tb[TCA_SAMPLE_PARMS] || !tb[TCA_SAMPLE_RATE] ||
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!tb[TCA_SAMPLE_PSAMPLE_GROUP])
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return -EINVAL;
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parm = nla_data(tb[TCA_SAMPLE_PARMS]);
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err = tcf_idr_check_alloc(tn, &parm->index, a, bind);
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if (err < 0)
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return err;
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exists = err;
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if (exists && bind)
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return 0;
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if (!exists) {
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ret = tcf_idr_create(tn, parm->index, est, a,
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&act_sample_ops, bind, true);
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if (ret) {
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tcf_idr_cleanup(tn, parm->index);
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return ret;
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}
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ret = ACT_P_CREATED;
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} else if (!ovr) {
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tcf_idr_release(*a, bind);
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return -EEXIST;
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}
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err = tcf_action_check_ctrlact(parm->action, tp, &goto_ch, extack);
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if (err < 0)
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goto release_idr;
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psample_group_num = nla_get_u32(tb[TCA_SAMPLE_PSAMPLE_GROUP]);
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psample_group = psample_group_get(net, psample_group_num);
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if (!psample_group) {
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err = -ENOMEM;
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goto put_chain;
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}
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s = to_sample(*a);
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spin_lock_bh(&s->tcf_lock);
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goto_ch = tcf_action_set_ctrlact(*a, parm->action, goto_ch);
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s->rate = nla_get_u32(tb[TCA_SAMPLE_RATE]);
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s->psample_group_num = psample_group_num;
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RCU_INIT_POINTER(s->psample_group, psample_group);
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if (tb[TCA_SAMPLE_TRUNC_SIZE]) {
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s->truncate = true;
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s->trunc_size = nla_get_u32(tb[TCA_SAMPLE_TRUNC_SIZE]);
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}
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spin_unlock_bh(&s->tcf_lock);
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if (goto_ch)
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tcf_chain_put_by_act(goto_ch);
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if (ret == ACT_P_CREATED)
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tcf_idr_insert(tn, *a);
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return ret;
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put_chain:
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if (goto_ch)
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tcf_chain_put_by_act(goto_ch);
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release_idr:
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tcf_idr_release(*a, bind);
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return err;
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}
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static void tcf_sample_cleanup(struct tc_action *a)
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{
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struct tcf_sample *s = to_sample(a);
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struct psample_group *psample_group;
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/* last reference to action, no need to lock */
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psample_group = rcu_dereference_protected(s->psample_group, 1);
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RCU_INIT_POINTER(s->psample_group, NULL);
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if (psample_group)
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psample_group_put(psample_group);
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}
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static bool tcf_sample_dev_ok_push(struct net_device *dev)
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{
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switch (dev->type) {
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case ARPHRD_TUNNEL:
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case ARPHRD_TUNNEL6:
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case ARPHRD_SIT:
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case ARPHRD_IPGRE:
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case ARPHRD_VOID:
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case ARPHRD_NONE:
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return false;
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default:
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return true;
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}
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}
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static int tcf_sample_act(struct sk_buff *skb, const struct tc_action *a,
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struct tcf_result *res)
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{
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struct tcf_sample *s = to_sample(a);
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struct psample_group *psample_group;
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int retval;
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int size;
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int iif;
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int oif;
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tcf_lastuse_update(&s->tcf_tm);
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bstats_cpu_update(this_cpu_ptr(s->common.cpu_bstats), skb);
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retval = READ_ONCE(s->tcf_action);
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psample_group = rcu_dereference_bh(s->psample_group);
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/* randomly sample packets according to rate */
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if (psample_group && (prandom_u32() % s->rate == 0)) {
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if (!skb_at_tc_ingress(skb)) {
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iif = skb->skb_iif;
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oif = skb->dev->ifindex;
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} else {
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iif = skb->dev->ifindex;
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oif = 0;
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}
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/* on ingress, the mac header gets popped, so push it back */
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if (skb_at_tc_ingress(skb) && tcf_sample_dev_ok_push(skb->dev))
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skb_push(skb, skb->mac_len);
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size = s->truncate ? s->trunc_size : skb->len;
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psample_sample_packet(psample_group, skb, size, iif, oif,
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s->rate);
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if (skb_at_tc_ingress(skb) && tcf_sample_dev_ok_push(skb->dev))
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skb_pull(skb, skb->mac_len);
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}
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return retval;
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}
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static int tcf_sample_dump(struct sk_buff *skb, struct tc_action *a,
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int bind, int ref)
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{
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unsigned char *b = skb_tail_pointer(skb);
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struct tcf_sample *s = to_sample(a);
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struct tc_sample opt = {
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.index = s->tcf_index,
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.refcnt = refcount_read(&s->tcf_refcnt) - ref,
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.bindcnt = atomic_read(&s->tcf_bindcnt) - bind,
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};
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struct tcf_t t;
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spin_lock_bh(&s->tcf_lock);
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opt.action = s->tcf_action;
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if (nla_put(skb, TCA_SAMPLE_PARMS, sizeof(opt), &opt))
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goto nla_put_failure;
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tcf_tm_dump(&t, &s->tcf_tm);
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if (nla_put_64bit(skb, TCA_SAMPLE_TM, sizeof(t), &t, TCA_SAMPLE_PAD))
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goto nla_put_failure;
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if (nla_put_u32(skb, TCA_SAMPLE_RATE, s->rate))
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goto nla_put_failure;
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if (s->truncate)
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if (nla_put_u32(skb, TCA_SAMPLE_TRUNC_SIZE, s->trunc_size))
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goto nla_put_failure;
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if (nla_put_u32(skb, TCA_SAMPLE_PSAMPLE_GROUP, s->psample_group_num))
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goto nla_put_failure;
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spin_unlock_bh(&s->tcf_lock);
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return skb->len;
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nla_put_failure:
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spin_unlock_bh(&s->tcf_lock);
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nlmsg_trim(skb, b);
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return -1;
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}
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static int tcf_sample_walker(struct net *net, struct sk_buff *skb,
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struct netlink_callback *cb, int type,
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const struct tc_action_ops *ops,
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struct netlink_ext_ack *extack)
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{
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struct tc_action_net *tn = net_generic(net, sample_net_id);
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return tcf_generic_walker(tn, skb, cb, type, ops, extack);
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}
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static int tcf_sample_search(struct net *net, struct tc_action **a, u32 index)
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{
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struct tc_action_net *tn = net_generic(net, sample_net_id);
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return tcf_idr_search(tn, a, index);
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}
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static struct tc_action_ops act_sample_ops = {
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.kind = "sample",
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.id = TCA_ID_SAMPLE,
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.owner = THIS_MODULE,
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.act = tcf_sample_act,
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.dump = tcf_sample_dump,
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.init = tcf_sample_init,
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.cleanup = tcf_sample_cleanup,
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.walk = tcf_sample_walker,
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.lookup = tcf_sample_search,
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.size = sizeof(struct tcf_sample),
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};
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static __net_init int sample_init_net(struct net *net)
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{
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struct tc_action_net *tn = net_generic(net, sample_net_id);
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return tc_action_net_init(tn, &act_sample_ops);
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}
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static void __net_exit sample_exit_net(struct list_head *net_list)
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{
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tc_action_net_exit(net_list, sample_net_id);
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}
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static struct pernet_operations sample_net_ops = {
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.init = sample_init_net,
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.exit_batch = sample_exit_net,
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.id = &sample_net_id,
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.size = sizeof(struct tc_action_net),
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};
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static int __init sample_init_module(void)
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{
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return tcf_register_action(&act_sample_ops, &sample_net_ops);
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}
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static void __exit sample_cleanup_module(void)
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{
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tcf_unregister_action(&act_sample_ops, &sample_net_ops);
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}
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module_init(sample_init_module);
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module_exit(sample_cleanup_module);
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MODULE_AUTHOR("Yotam Gigi <yotam.gi@gmail.com>");
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MODULE_DESCRIPTION("Packet sampling action");
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MODULE_LICENSE("GPL v2");
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