![Davide Caratti](/assets/img/avatar_default.png)
the following script: # tc qdisc add dev crash0 clsact # tc filter add dev crash0 egress matchall \ > action simple sdata hello pass index 90 # tc actions replace action simple \ > sdata world goto chain 42 index 90 cookie c1a0c1a0 # tc action show action simple 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: Simple <world> 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 800000006a6fb067 P4D 800000006a6fb067 PUD 6aed6067 PMD 0 Oops: 0000 [#1] SMP PTI CPU: 2 PID: 3241 Comm: kworker/2:0 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:ffffbe6781763ad0 EFLAGS: 00010246 RAX: 000000002000002a RBX: ffff9e59bdb80e00 RCX: 0000000000000000 RDX: 0000000000000000 RSI: ffff9e59b4716738 RDI: ffff9e59ab12d140 RBP: ffffbe6781763b70 R08: 0000000000000234 R09: 0000000000aaaaaa R10: 0000000000000000 R11: ffff9e59b247cd50 R12: ffff9e59b112f100 R13: ffff9e59b112f108 R14: 0000000000000001 R15: ffff9e59ab12d0c0 FS: 0000000000000000(0000) GS:ffff9e59b4700000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000000 CR3: 000000006af92004 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_simple 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 virtio_balloon pcspkr soundcore 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 net_failover virtio_console virtio_blk failover drm crc32c_intel serio_raw floppy ata_piix libata virtio_pci virtio_ring virtio dm_mirror dm_region_hash dm_log dm_mod CR2: 0000000000000000 Validating the control action within tcf_simple_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>
271 lines
6.6 KiB
C
271 lines
6.6 KiB
C
/*
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* net/sched/act_simple.c Simple example of an action
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*
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* Authors: Jamal Hadi Salim (2005-8)
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*
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*/
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#include <linux/module.h>
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#include <linux/slab.h>
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#include <linux/init.h>
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#include <linux/kernel.h>
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#include <linux/skbuff.h>
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#include <linux/rtnetlink.h>
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#include <net/netlink.h>
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#include <net/pkt_sched.h>
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#include <net/pkt_cls.h>
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#include <linux/tc_act/tc_defact.h>
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#include <net/tc_act/tc_defact.h>
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static unsigned int simp_net_id;
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static struct tc_action_ops act_simp_ops;
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#define SIMP_MAX_DATA 32
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static int tcf_simp_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_defact *d = to_defact(a);
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spin_lock(&d->tcf_lock);
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tcf_lastuse_update(&d->tcf_tm);
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bstats_update(&d->tcf_bstats, skb);
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/* print policy string followed by _ then packet count
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* Example if this was the 3rd packet and the string was "hello"
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* then it would look like "hello_3" (without quotes)
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*/
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pr_info("simple: %s_%d\n",
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(char *)d->tcfd_defdata, d->tcf_bstats.packets);
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spin_unlock(&d->tcf_lock);
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return d->tcf_action;
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}
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static void tcf_simp_release(struct tc_action *a)
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{
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struct tcf_defact *d = to_defact(a);
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kfree(d->tcfd_defdata);
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}
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static int alloc_defdata(struct tcf_defact *d, const struct nlattr *defdata)
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{
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d->tcfd_defdata = kzalloc(SIMP_MAX_DATA, GFP_KERNEL);
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if (unlikely(!d->tcfd_defdata))
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return -ENOMEM;
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nla_strlcpy(d->tcfd_defdata, defdata, SIMP_MAX_DATA);
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return 0;
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}
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static int reset_policy(struct tc_action *a, const struct nlattr *defdata,
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struct tc_defact *p, struct tcf_proto *tp,
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struct netlink_ext_ack *extack)
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{
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struct tcf_chain *goto_ch = NULL;
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struct tcf_defact *d;
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int err;
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err = tcf_action_check_ctrlact(p->action, tp, &goto_ch, extack);
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if (err < 0)
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return err;
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d = to_defact(a);
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spin_lock_bh(&d->tcf_lock);
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goto_ch = tcf_action_set_ctrlact(a, p->action, goto_ch);
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memset(d->tcfd_defdata, 0, SIMP_MAX_DATA);
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nla_strlcpy(d->tcfd_defdata, defdata, SIMP_MAX_DATA);
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spin_unlock_bh(&d->tcf_lock);
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if (goto_ch)
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tcf_chain_put_by_act(goto_ch);
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return 0;
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}
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static const struct nla_policy simple_policy[TCA_DEF_MAX + 1] = {
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[TCA_DEF_PARMS] = { .len = sizeof(struct tc_defact) },
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[TCA_DEF_DATA] = { .type = NLA_STRING, .len = SIMP_MAX_DATA },
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};
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static int tcf_simp_init(struct net *net, struct nlattr *nla,
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struct nlattr *est, struct tc_action **a,
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int ovr, int bind, bool rtnl_held,
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struct tcf_proto *tp, struct netlink_ext_ack *extack)
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{
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struct tc_action_net *tn = net_generic(net, simp_net_id);
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struct nlattr *tb[TCA_DEF_MAX + 1];
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struct tcf_chain *goto_ch = NULL;
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struct tc_defact *parm;
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struct tcf_defact *d;
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bool exists = false;
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int ret = 0, err;
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if (nla == NULL)
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return -EINVAL;
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err = nla_parse_nested(tb, TCA_DEF_MAX, nla, simple_policy, NULL);
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if (err < 0)
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return err;
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if (tb[TCA_DEF_PARMS] == NULL)
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return -EINVAL;
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parm = nla_data(tb[TCA_DEF_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 (tb[TCA_DEF_DATA] == NULL) {
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if (exists)
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tcf_idr_release(*a, bind);
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else
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tcf_idr_cleanup(tn, parm->index);
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return -EINVAL;
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}
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if (!exists) {
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ret = tcf_idr_create(tn, parm->index, est, a,
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&act_simp_ops, bind, false);
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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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d = to_defact(*a);
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err = tcf_action_check_ctrlact(parm->action, tp, &goto_ch,
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extack);
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if (err < 0)
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goto release_idr;
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err = alloc_defdata(d, tb[TCA_DEF_DATA]);
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if (err < 0)
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goto put_chain;
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tcf_action_set_ctrlact(*a, parm->action, goto_ch);
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ret = ACT_P_CREATED;
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} else {
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if (!ovr) {
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err = -EEXIST;
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goto release_idr;
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}
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err = reset_policy(*a, tb[TCA_DEF_DATA], parm, tp, extack);
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if (err)
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goto release_idr;
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}
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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 int tcf_simp_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_defact *d = to_defact(a);
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struct tc_defact opt = {
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.index = d->tcf_index,
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.refcnt = refcount_read(&d->tcf_refcnt) - ref,
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.bindcnt = atomic_read(&d->tcf_bindcnt) - bind,
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};
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struct tcf_t t;
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spin_lock_bh(&d->tcf_lock);
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opt.action = d->tcf_action;
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if (nla_put(skb, TCA_DEF_PARMS, sizeof(opt), &opt) ||
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nla_put_string(skb, TCA_DEF_DATA, d->tcfd_defdata))
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goto nla_put_failure;
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tcf_tm_dump(&t, &d->tcf_tm);
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if (nla_put_64bit(skb, TCA_DEF_TM, sizeof(t), &t, TCA_DEF_PAD))
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goto nla_put_failure;
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spin_unlock_bh(&d->tcf_lock);
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return skb->len;
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nla_put_failure:
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spin_unlock_bh(&d->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_simp_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, simp_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_simp_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, simp_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_simp_ops = {
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.kind = "simple",
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.id = TCA_ID_SIMP,
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.owner = THIS_MODULE,
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.act = tcf_simp_act,
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.dump = tcf_simp_dump,
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.cleanup = tcf_simp_release,
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.init = tcf_simp_init,
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.walk = tcf_simp_walker,
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.lookup = tcf_simp_search,
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.size = sizeof(struct tcf_defact),
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};
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static __net_init int simp_init_net(struct net *net)
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{
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struct tc_action_net *tn = net_generic(net, simp_net_id);
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return tc_action_net_init(tn, &act_simp_ops);
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}
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static void __net_exit simp_exit_net(struct list_head *net_list)
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{
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tc_action_net_exit(net_list, simp_net_id);
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}
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static struct pernet_operations simp_net_ops = {
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.init = simp_init_net,
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.exit_batch = simp_exit_net,
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.id = &simp_net_id,
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.size = sizeof(struct tc_action_net),
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};
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MODULE_AUTHOR("Jamal Hadi Salim(2005)");
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MODULE_DESCRIPTION("Simple example action");
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MODULE_LICENSE("GPL");
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static int __init simp_init_module(void)
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{
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int ret = tcf_register_action(&act_simp_ops, &simp_net_ops);
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if (!ret)
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pr_info("Simple TC action Loaded\n");
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return ret;
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}
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static void __exit simp_cleanup_module(void)
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{
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tcf_unregister_action(&act_simp_ops, &simp_net_ops);
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}
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module_init(simp_init_module);
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module_exit(simp_cleanup_module);
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