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net/sched: act_simple: validate the control action inside init() 

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>
This commit is contained in:
Davide Caratti 2019-03-20 15:00:10 +01:00 committed by David S. Miller
parent e8c87c643e
commit 4b006b0c13
2 changed files with 63 additions and 14 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

52
net/sched/act_simple.c
View File

@ -18,6 +18,7 @@
#include <linux/rtnetlink.h>
#include <net/netlink.h>
#include <net/pkt_sched.h>
#include <net/pkt_cls.h>
#include <linux/tc_act/tc_defact.h>
#include <net/tc_act/tc_defact.h>
@ -60,14 +61,26 @@ 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 tc_action *a, const struct nlattr *defdata,
struct tc_defact *p, struct tcf_proto *tp,
struct netlink_ext_ack *extack)
{
struct tcf_chain *goto_ch = NULL;
struct tcf_defact *d;
int err;
err = tcf_action_check_ctrlact(p->action, tp, &goto_ch, extack);
if (err < 0)
return err;
d = to_defact(a);
spin_lock_bh(&d->tcf_lock);
d->tcf_action = p->action;
goto_ch = tcf_action_set_ctrlact(a, p->action, goto_ch);
memset(d->tcfd_defdata, 0, SIMP_MAX_DATA);
nla_strlcpy(d->tcfd_defdata, defdata, SIMP_MAX_DATA);
spin_unlock_bh(&d->tcf_lock);
if (goto_ch)
tcf_chain_put_by_act(goto_ch);
return 0;
}
static const struct nla_policy simple_policy[TCA_DEF_MAX + 1] = {
@ -82,6 +95,7 @@ static int tcf_simp_init(struct net *net, struct nlattr *nla,
{
struct tc_action_net *tn = net_generic(net, simp_net_id);
struct nlattr *tb[TCA_DEF_MAX + 1];
struct tcf_chain *goto_ch = NULL;
struct tc_defact *parm;
struct tcf_defact *d;
bool exists = false;
@ -122,27 +136,37 @@ 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;
}
d->tcf_action = parm->action;
err = tcf_action_check_ctrlact(parm->action, tp, &goto_ch,
extack);
if (err < 0)
goto release_idr;
err = alloc_defdata(d, tb[TCA_DEF_DATA]);
if (err < 0)
goto put_chain;
tcf_action_set_ctrlact(*a, parm->action, goto_ch);
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(*a, tb[TCA_DEF_DATA], parm, tp, extack);
if (err)
goto release_idr;
}
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 int tcf_simp_dump(struct sk_buff *skb, struct tc_action *a,

25
tools/testing/selftests/tc-testing/tc-tests/actions/simple.json
View File

@ -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"
]
}
]