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Date: Wed, 27 Feb 2019 18:40:41 +0100
From: Davide Caratti <dcaratti@...hat.com>
To: "David S. Miller" <davem@...emloft.net>,
Jamal Hadi Salim <jhs@...atatu.com>,
Cong Wang <xiyou.wangcong@...il.com>,
Jiri Pirko <jiri@...nulli.us>,
Vlad Buslov <vladbu@...lanox.com>
Cc: pabeni@...hat.com, netdev@...r.kernel.org
Subject: [PATCH net 13/16] net/sched: act_skbedit: validate the control action inside init()
the following script:
# tc qdisc add dev crash0 clsact
# tc filter add dev crash0 egress matchall \
> action skbedit ptype host pass index 90
# tc actions replace action skbedit \
> ptype host goto chain 42 index 90 cookie c1a0c1a0
# tc actions show action skbedit
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: skbedit ptype host 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 0 P4D 0
Oops: 0000 [#1] SMP PTI
CPU: 3 PID: 3467 Comm: kworker/3:3 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:ffffb50a81e1fad0 EFLAGS: 00010246
RAX: 000000002000002a RBX: ffff9aa47ba4ea00 RCX: 0000000000000001
RDX: 0000000000000000 RSI: ffff9aa469eeb3c0 RDI: ffff9aa47ba4ea00
RBP: ffffb50a81e1fb70 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: ffff9aa47bce0638 R12: ffff9aa4793b0c00
R13: ffff9aa4793b0c08 R14: 0000000000000001 R15: ffff9aa469eeb3c0
FS: 0000000000000000(0000) GS:ffff9aa474780000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 000000007360e005 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_skbedit 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 soundcore pcspkr virtio_balloon 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 ttm virtio_net net_failover drm failover virtio_blk virtio_console ata_piix virtio_pci crc32c_intel serio_raw libata virtio_ring virtio floppy dm_mirror dm_region_hash dm_log dm_mod
CR2: 0000000000000000
Validating the control action within tcf_skbedit_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 <dcaratti@...hat.com>
---
net/sched/act_skbedit.c | 22 +++++++++++++---
.../tc-testing/tc-tests/actions/skbedit.json | 25 +++++++++++++++++++
2 files changed, 43 insertions(+), 4 deletions(-)
diff --git a/net/sched/act_skbedit.c b/net/sched/act_skbedit.c
index 9a8a0f2d4418..5a0d35b2dac3 100644
--- a/net/sched/act_skbedit.c
+++ b/net/sched/act_skbedit.c
@@ -26,6 +26,7 @@
#include <net/ip.h>
#include <net/ipv6.h>
#include <net/dsfield.h>
+#include <net/pkt_cls.h>
#include <linux/tc_act/tc_skbedit.h>
#include <net/tc_act/tc_skbedit.h>
@@ -100,6 +101,7 @@ static int tcf_skbedit_init(struct net *net, struct nlattr *nla,
struct netlink_ext_ack *extack)
{
struct tc_action_net *tn = net_generic(net, skbedit_net_id);
+ struct tcf_chain *newchain = NULL, *oldchain;
struct tcf_skbedit_params *params_new;
struct nlattr *tb[TCA_SKBEDIT_MAX + 1];
struct tc_skbedit *parm;
@@ -187,12 +189,13 @@ static int tcf_skbedit_init(struct net *net, struct nlattr *nla,
return -EEXIST;
}
}
+ err = tcf_action_check_ctrlact(parm->action, tp, &newchain, extack);
+ if (err)
+ goto release_idr;
params_new = kzalloc(sizeof(*params_new), GFP_KERNEL);
- if (unlikely(!params_new)) {
- tcf_idr_release(*a, bind);
- return -ENOMEM;
- }
+ if (unlikely(!params_new))
+ goto put_chain;
params_new->flags = flags;
if (flags & SKBEDIT_F_PRIORITY)
@@ -209,6 +212,8 @@ static int tcf_skbedit_init(struct net *net, struct nlattr *nla,
params_new->mask = *mask;
spin_lock_bh(&d->tcf_lock);
+ oldchain = d->tcf_goto_chain;
+ d->tcf_goto_chain = newchain;
d->tcf_action = parm->action;
rcu_swap_protected(d->params, params_new,
lockdep_is_held(&d->tcf_lock));
@@ -218,7 +223,16 @@ static int tcf_skbedit_init(struct net *net, struct nlattr *nla,
if (ret == ACT_P_CREATED)
tcf_idr_insert(tn, *a);
+ if (oldchain)
+ tcf_chain_put_by_act(oldchain);
return ret;
+
+put_chain:
+ if (newchain)
+ tcf_chain_put_by_act(newchain);
+release_idr:
+ tcf_idr_release(*a, bind);
+ return err;
}
static int tcf_skbedit_dump(struct sk_buff *skb, struct tc_action *a,
diff --git a/tools/testing/selftests/tc-testing/tc-tests/actions/skbedit.json b/tools/testing/selftests/tc-testing/tc-tests/actions/skbedit.json
index 5aaf593b914a..ecd96eda7f6a 100644
--- a/tools/testing/selftests/tc-testing/tc-tests/actions/skbedit.json
+++ b/tools/testing/selftests/tc-testing/tc-tests/actions/skbedit.json
@@ -484,5 +484,30 @@
"teardown": [
"$TC actions flush action skbedit"
]
+ },
+ {
+ "id": "1b2b",
+ "name": "Replace skbedit action with invalid goto_chain control",
+ "category": [
+ "actions",
+ "skbedit"
+ ],
+ "setup": [
+ [
+ "$TC actions flush action skbedit",
+ 0,
+ 1,
+ 255
+ ],
+ "$TC actions add action skbedit ptype host pass index 90"
+ ],
+ "cmdUnderTest": "$TC actions replace action skbedit ptype host goto chain 42 index 90 cookie c1a0c1a0",
+ "expExitCode": "255",
+ "verifyCmd": "$TC actions list action skbedit",
+ "matchPattern": "action order [0-9]*: skbedit ptype host pass.*index 90 ref",
+ "matchCount": "1",
+ "teardown": [
+ "$TC actions flush action skbedit"
+ ]
}
]
--
2.20.1
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