On Wed 27 Feb 2019 at 17:40, Davide Caratti <dcara...@redhat.com> wrote:
> 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: db50514f9a9c ("net: sched: add termination action to allow goto chain")
> Fixes: 97763dc0f401 ("net_sched: reject unknown tcfa_action values")
> Signed-off-by: Davide Caratti <dcara...@redhat.com>
> ---
> net/sched/act_simple.c | 50 +++++++++++++++----
> .../tc-testing/tc-tests/actions/simple.json | 25 ++++++++++
> 2 files changed, 65 insertions(+), 10 deletions(-)
>
> diff --git a/net/sched/act_simple.c b/net/sched/act_simple.c
> index 640ee5b785dc..ca8ef8378c33 100644
> --- a/net/sched/act_simple.c
> +++ b/net/sched/act_simple.c
> @@ -18,6 +18,7 @@
> #include <linux/rtnetlink.h>
> #include <net/netlink.h>
> #include <net/pkt_sched.h>
> +#include <net/pkt_cls.h>
>
> #define TCA_ACT_SIMP 22
>
> @@ -62,14 +63,28 @@ static int alloc_defdata(struct tcf_defact *d, const
> struct nlattr *defdata)
> return 0;
> }
>
> -static void reset_policy(struct tcf_defact *d, const struct nlattr *defdata,
> - struct tc_defact *p)
> +static int reset_policy(struct tcf_defact *d, const struct nlattr *defdata,
> + struct tc_defact *p, struct tcf_proto *tp,
> + struct netlink_ext_ack *extack)
> {
> + struct tcf_chain *newchain = NULL, *oldchain;
> + int err;
> +
> + err = tcf_action_check_ctrlact(p->action, tp, &newchain, extack);
> + if (err)
> + return err;
> +
> spin_lock_bh(&d->tcf_lock);
> + oldchain = d->tcf_goto_chain;
> + d->tcf_goto_chain = newchain;
> d->tcf_action = p->action;
> memset(d->tcfd_defdata, 0, SIMP_MAX_DATA);
> nla_strlcpy(d->tcfd_defdata, defdata, SIMP_MAX_DATA);
> spin_unlock_bh(&d->tcf_lock);
> +
> + if (oldchain)
> + tcf_chain_put_by_act(oldchain);
> + return err;
> }
>
> static const struct nla_policy simple_policy[TCA_DEF_MAX + 1] = {
> @@ -83,6 +98,7 @@ static int tcf_simp_init(struct net *net, struct nlattr
> *nla,
> struct tcf_proto *tp, struct netlink_ext_ack *extack)
> {
> struct tc_action_net *tn = net_generic(net, simp_net_id);
> + struct tcf_chain *newchain = NULL, *oldchain;
> struct nlattr *tb[TCA_DEF_MAX + 1];
> struct tc_defact *parm;
> struct tcf_defact *d;
> @@ -124,27 +140,41 @@ static int tcf_simp_init(struct net *net, struct nlattr
> *nla,
> }
>
> d = to_defact(*a);
> - ret = alloc_defdata(d, tb[TCA_DEF_DATA]);
> - if (ret < 0) {
> - tcf_idr_release(*a, bind);
> - return ret;
> - }
> + err = tcf_action_check_ctrlact(parm->action, tp, &newchain,
> + extack);
> + if (err < 0)
> + goto release_idr;
> +
> + err = alloc_defdata(d, tb[TCA_DEF_DATA]);
> + if (err < 0)
> + goto release_idr;
This should jump to error handler that releases newchain besides idr.
> +
> + oldchain = d->tcf_goto_chain;
> + d->tcf_goto_chain = newchain;
> d->tcf_action = parm->action;
> + if (oldchain)
> + tcf_chain_put_by_act(oldchain);
> ret = ACT_P_CREATED;
> } else {
> d = to_defact(*a);
>
> if (!ovr) {
> - tcf_idr_release(*a, bind);
> - return -EEXIST;
> + err = -EEXIST;
> + goto release_idr;
> }
>
> - reset_policy(d, tb[TCA_DEF_DATA], parm);
> + err = reset_policy(d, tb[TCA_DEF_DATA], parm, tp, extack);
> + if (err)
> + goto release_idr;
> }
>
> if (ret == ACT_P_CREATED)
> tcf_idr_insert(tn, *a);
> return ret;
> +
> +release_idr:
> + tcf_idr_release(*a, bind);
> + return err;
> }
>
> static int tcf_simp_dump(struct sk_buff *skb, struct tc_action *a,
> diff --git a/tools/testing/selftests/tc-testing/tc-tests/actions/simple.json
> b/tools/testing/selftests/tc-testing/tc-tests/actions/simple.json
> index e89a7aa4012d..8e8c1ae12260 100644
> --- a/tools/testing/selftests/tc-testing/tc-tests/actions/simple.json
> +++ b/tools/testing/selftests/tc-testing/tc-tests/actions/simple.json
> @@ -126,5 +126,30 @@
> "teardown": [
> ""
> ]
> + },
> + {
> + "id": "b776",
> + "name": "Replace simple action with invalid goto chain control",
> + "category": [
> + "actions",
> + "simple"
> + ],
> + "setup": [
> + [
> + "$TC actions flush action simple",
> + 0,
> + 1,
> + 255
> + ],
> + "$TC actions add action simple sdata \"hello\" pass index 90"
> + ],
> + "cmdUnderTest": "$TC actions replace action simple sdata \"world\"
> goto chain 42 index 90 cookie c1a0c1a0",
> + "expExitCode": "255",
> + "verifyCmd": "$TC actions list action simple",
> + "matchPattern": "action order [0-9]*: Simple <hello>.*index 90 ref",
> + "matchCount": "1",
> + "teardown": [
> + "$TC actions flush action simple"
> + ]
> }
> ]
