[PATCH net 0/2] net/sched: fix NULL dereference in 'goto chain' control action

[PATCH net 0/2] net/sched: fix NULL dereference in 'goto chain' control action

[Davide Caratti]

in a couple of TC actions (i.e. csum and tunnel_key), the control action
is stored together with the action-specific configuration data.
This avoids a race condition (see [1]), but it causes a crash when 'goto
chain' is used with the above actions. Since this race condition is
tolerated on the other TC actions (it's present even on actions where the
spinlock is still used), storing the control action in the common area
should be acceptable for tunnel_key and csum as well.

[1] https://www.spinics.net/lists/netdev/msg472047.html

Davide Caratti (2):
  net/sched: act_csum: fix NULL dereference when 'goto chain' is used
  net/sched: act_tunnel_key: fix NULL dereference when 'goto chain' is
    used

 include/net/tc_act/tc_csum.h       | 1 -
 include/net/tc_act/tc_tunnel_key.h | 1 -
 net/sched/act_csum.c               | 6 +++---
 net/sched/act_tunnel_key.c         | 6 +++---
 4 files changed, 6 insertions(+), 8 deletions(-)

-- 
2.17.1

[PATCH net 1/2] net/sched: act_csum: fix NULL dereference when 'goto chain' is used

[Davide Caratti]

the control action in the common member of struct tcf_csum must be a valid
value, as it can contain the chain index when 'goto chain' is used. Ensure
that the control action can be read as x->tcfa_action, when x is a pointer
to struct tc_action and x->ops->type is TCA_ACT_CSUM, to prevent the
following command:

  # tc filter add dev $h2 ingress protocol ip pref 1 handle 101 flower \
  > $tcflags dst_mac $h2mac action csum ip or tcp or udp or sctp goto chain 1

from triggering a NULL pointer dereference when a matching packet is
received.

 BUG: unable to handle kernel NULL pointer dereference at 0000000000000000
 PGD 800000010416b067 P4D 800000010416b067 PUD 1041be067 PMD 0
 Oops: 0000 [#1] SMP PTI
 CPU: 0 PID: 3072 Comm: mausezahn Tainted: G            E     4.18.0-rc2.auguri+ #421
 Hardware name: Hewlett-Packard HP Z220 CMT Workstation/1790, BIOS K51 v01.58 02/07/2013
 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:ffffa020dea03c40 EFLAGS: 00010246
 RAX: 0000000020000001 RBX: ffffa020d7ccef00 RCX: 0000000000000054
 RDX: 0000000000000000 RSI: ffffa020ca5ae000 RDI: ffffa020d7ccef00
 RBP: ffffa020dea03e60 R08: 0000000000000000 R09: ffffa020dea03c9c
 R10: ffffa020dea03c78 R11: 0000000000000008 R12: ffffa020d3fe4f00
 R13: ffffa020d3fe4f08 R14: 0000000000000001 R15: ffffa020d53ca300
 FS:  00007f5a46942740(0000) GS:ffffa020dea00000(0000) knlGS:0000000000000000
 CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
 CR2: 0000000000000000 CR3: 0000000104218002 CR4: 00000000001606f0
 Call Trace:
  <IRQ>
  fl_classify+0x1ad/0x1c0 [cls_flower]
  ? arp_rcv+0x121/0x1b0
  ? __x2apic_send_IPI_dest+0x40/0x40
  ? smp_reschedule_interrupt+0x1c/0xd0
  ? reschedule_interrupt+0xf/0x20
  ? reschedule_interrupt+0xa/0x20
  ? device_is_rmrr_locked+0xe/0x50
  ? iommu_should_identity_map+0x49/0xd0
  ? __intel_map_single+0x30/0x140
  ? e1000e_update_rdt_wa.isra.52+0x22/0xb0 [e1000e]
  ? e1000_alloc_rx_buffers+0x233/0x250 [e1000e]
  ? kmem_cache_alloc+0x38/0x1c0
  tcf_classify+0x89/0x140
  __netif_receive_skb_core+0x5ea/0xb70
  ? enqueue_task_fair+0xb6/0x7d0
  ? process_backlog+0x97/0x150
  process_backlog+0x97/0x150
  net_rx_action+0x14b/0x3e0
  __do_softirq+0xde/0x2b4
  do_softirq_own_stack+0x2a/0x40
  </IRQ>
  do_softirq.part.18+0x49/0x50
  __local_bh_enable_ip+0x49/0x50
  __dev_queue_xmit+0x4ab/0x8a0
  ? wait_woken+0x80/0x80
  ? packet_sendmsg+0x38f/0x810
  ? __dev_queue_xmit+0x8a0/0x8a0
  packet_sendmsg+0x38f/0x810
  sock_sendmsg+0x36/0x40
  __sys_sendto+0x10e/0x140
  ? do_vfs_ioctl+0xa4/0x630
  ? syscall_trace_enter+0x1df/0x2e0
  ? __audit_syscall_exit+0x22a/0x290
  __x64_sys_sendto+0x24/0x30
  do_syscall_64+0x5b/0x180
  entry_SYSCALL_64_after_hwframe+0x44/0xa9
 RIP: 0033:0x7f5a45cbec93
 Code: 48 8b 0d 18 83 20 00 f7 d8 64 89 01 48 83 c8 ff c3 66 0f 1f 44 00 00 83 3d 59 c7 20 00 00 75 13 49 89 ca b8 2c 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 34 c3 48 83 ec 08 e8 2b f7 ff ff 48 89 04 24
 RSP: 002b:00007ffd0ee6d748 EFLAGS: 00000246 ORIG_RAX: 000000000000002c
 RAX: ffffffffffffffda RBX: 0000000001161010 RCX: 00007f5a45cbec93
 RDX: 0000000000000062 RSI: 0000000001161322 RDI: 0000000000000003
 RBP: 00007ffd0ee6d780 R08: 00007ffd0ee6d760 R09: 0000000000000014
 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000062
 R13: 0000000001161322 R14: 00007ffd0ee6d760 R15: 0000000000000003
 Modules linked in: act_csum act_gact cls_flower sch_ingress vrf veth act_tunnel_key(E) xt_CHECKSUM iptable_mangle ipt_MASQUERADE iptable_nat nf_nat_ipv4 nf_nat nf_conntrack_ipv4 nf_defrag_ipv4 xt_conntrack nf_conntrack ipt_REJECT nf_reject_ipv4 tun bridge stp llc ebtable_filter ebtables ip6table_filter ip6_tables iptable_filter intel_rapl x86_pkg_temp_thermal intel_powerclamp coretemp kvm_intel snd_hda_codec_hdmi snd_hda_codec_realtek kvm snd_hda_codec_generic hp_wmi iTCO_wdt sparse_keymap rfkill mei_wdt iTCO_vendor_support wmi_bmof gpio_ich irqbypass crct10dif_pclmul crc32_pclmul ghash_clmulni_intel pcbc aesni_intel snd_hda_intel crypto_simd cryptd snd_hda_codec glue_helper snd_hda_core snd_hwdep snd_seq snd_seq_device snd_pcm pcspkr i2c_i801 snd_timer snd sg lpc_ich soundcore wmi mei_me
 
  mei ie31200_edac nfsd auth_rpcgss nfs_acl lockd grace sunrpc ip_tables xfs libcrc32c sr_mod cdrom sd_mod ahci libahci crc32c_intel i915 ixgbe serio_raw libata video dca i2c_algo_bit sfc drm_kms_helper syscopyarea mtd sysfillrect mdio sysimgblt fb_sys_fops drm e1000e i2c_core
 CR2: 0000000000000000
 ---[ end trace 3c9e9d1a77df4026 ]---
 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:ffffa020dea03c40 EFLAGS: 00010246
 RAX: 0000000020000001 RBX: ffffa020d7ccef00 RCX: 0000000000000054
 RDX: 0000000000000000 RSI: ffffa020ca5ae000 RDI: ffffa020d7ccef00
 RBP: ffffa020dea03e60 R08: 0000000000000000 R09: ffffa020dea03c9c
 R10: ffffa020dea03c78 R11: 0000000000000008 R12: ffffa020d3fe4f00
 R13: ffffa020d3fe4f08 R14: 0000000000000001 R15: ffffa020d53ca300
 FS:  00007f5a46942740(0000) GS:ffffa020dea00000(0000) knlGS:0000000000000000
 CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
 CR2: 0000000000000000 CR3: 0000000104218002 CR4: 00000000001606f0
 Kernel panic - not syncing: Fatal exception in interrupt
 Kernel Offset: 0x26400000 from 0xffffffff81000000 (relocation range: 0xffffffff80000000-0xffffffffbfffffff)
 ---[ end Kernel panic - not syncing: Fatal exception in interrupt ]---

Fixes: 9c5f69bbd75a ("net/sched: act_csum: don't use spinlock in the fast path")
Signed-off-by: Davide Caratti <dcaratti@redhat.com>
---
 include/net/tc_act/tc_csum.h | 1 -
 net/sched/act_csum.c         | 6 +++---
 2 files changed, 3 insertions(+), 4 deletions(-)

diff --git a/include/net/tc_act/tc_csum.h b/include/net/tc_act/tc_csum.h
index 9470fd7e4350..32d2454c0479 100644
--- a/include/net/tc_act/tc_csum.h
+++ b/include/net/tc_act/tc_csum.h
@@ -7,7 +7,6 @@
 #include <linux/tc_act/tc_csum.h>
 
 struct tcf_csum_params {
-	int action;
 	u32 update_flags;
 	struct rcu_head rcu;
 };
diff --git a/net/sched/act_csum.c b/net/sched/act_csum.c
index 526a8e491626..6e7124e57918 100644
--- a/net/sched/act_csum.c
+++ b/net/sched/act_csum.c
@@ -91,7 +91,7 @@ static int tcf_csum_init(struct net *net, struct nlattr *nla,
 	}
 	params_old = rtnl_dereference(p->params);
 
-	params_new->action = parm->action;
+	p->tcf_action = parm->action;
 	params_new->update_flags = parm->update_flags;
 	rcu_assign_pointer(p->params, params_new);
 	if (params_old)
@@ -561,7 +561,7 @@ static int tcf_csum(struct sk_buff *skb, const struct tc_action *a,
 	tcf_lastuse_update(&p->tcf_tm);
 	bstats_cpu_update(this_cpu_ptr(p->common.cpu_bstats), skb);
 
-	action = params->action;
+	action = READ_ONCE(p->tcf_action);
 	if (unlikely(action == TC_ACT_SHOT))
 		goto drop_stats;
 
@@ -599,11 +599,11 @@ static int tcf_csum_dump(struct sk_buff *skb, struct tc_action *a, int bind,
 		.index   = p->tcf_index,
 		.refcnt  = p->tcf_refcnt - ref,
 		.bindcnt = p->tcf_bindcnt - bind,
+		.action  = p->tcf_action,
 	};
 	struct tcf_t t;
 
 	params = rtnl_dereference(p->params);
-	opt.action = params->action;
 	opt.update_flags = params->update_flags;
 
 	if (nla_put(skb, TCA_CSUM_PARMS, sizeof(opt), &opt))
-- 
2.17.1

[PATCH net 2/2] net/sched: act_tunnel_key: fix NULL dereference when 'goto chain' is used

[Davide Caratti]

the control action in the common member of struct tcf_tunnel_key must be a
valid value, as it can contain the chain index when 'goto chain' is used.
Ensure that the control action can be read as x->tcfa_action, when x is a
pointer to struct tc_action and x->ops->type is TCA_ACT_TUNNEL_KEY, to
prevent the following command:

 # tc filter add dev $h2 ingress protocol ip pref 1 handle 101 flower \
 > $tcflags dst_mac $h2mac action tunnel_key unset goto chain 1

from causing a NULL dereference when a matching packet is received:

 BUG: unable to handle kernel NULL pointer dereference at 0000000000000000
 PGD 80000001097ac067 P4D 80000001097ac067 PUD 103b0a067 PMD 0
 Oops: 0000 [#1] SMP PTI
 CPU: 0 PID: 3491 Comm: mausezahn Tainted: G            E     4.18.0-rc2.auguri+ #421
 Hardware name: Hewlett-Packard HP Z220 CMT Workstation/1790, BIOS K51 v01.58 02/07/2013
 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:ffff95145ea03c40 EFLAGS: 00010246
 RAX: 0000000020000001 RBX: ffff9514499e5800 RCX: 0000000000000001
 RDX: 0000000000000000 RSI: 0000000000000002 RDI: 0000000000000000
 RBP: ffff95145ea03e60 R08: 0000000000000000 R09: ffff95145ea03c9c
 R10: ffff95145ea03c78 R11: 0000000000000008 R12: ffff951456a69800
 R13: ffff951456a69808 R14: 0000000000000001 R15: ffff95144965ee40
 FS:  00007fd67ee11740(0000) GS:ffff95145ea00000(0000) knlGS:0000000000000000
 CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
 CR2: 0000000000000000 CR3: 00000001038a2006 CR4: 00000000001606f0
 Call Trace:
  <IRQ>
  fl_classify+0x1ad/0x1c0 [cls_flower]
  ? __update_load_avg_se.isra.47+0x1ca/0x1d0
  ? __update_load_avg_se.isra.47+0x1ca/0x1d0
  ? update_load_avg+0x665/0x690
  ? update_load_avg+0x665/0x690
  ? kmem_cache_alloc+0x38/0x1c0
  tcf_classify+0x89/0x140
  __netif_receive_skb_core+0x5ea/0xb70
  ? enqueue_entity+0xd0/0x270
  ? process_backlog+0x97/0x150
  process_backlog+0x97/0x150
  net_rx_action+0x14b/0x3e0
  __do_softirq+0xde/0x2b4
  do_softirq_own_stack+0x2a/0x40
  </IRQ>
  do_softirq.part.18+0x49/0x50
  __local_bh_enable_ip+0x49/0x50
  __dev_queue_xmit+0x4ab/0x8a0
  ? wait_woken+0x80/0x80
  ? packet_sendmsg+0x38f/0x810
  ? __dev_queue_xmit+0x8a0/0x8a0
  packet_sendmsg+0x38f/0x810
  sock_sendmsg+0x36/0x40
  __sys_sendto+0x10e/0x140
  ? do_vfs_ioctl+0xa4/0x630
  ? syscall_trace_enter+0x1df/0x2e0
  ? __audit_syscall_exit+0x22a/0x290
  __x64_sys_sendto+0x24/0x30
  do_syscall_64+0x5b/0x180
  entry_SYSCALL_64_after_hwframe+0x44/0xa9
 RIP: 0033:0x7fd67e18dc93
 Code: 48 8b 0d 18 83 20 00 f7 d8 64 89 01 48 83 c8 ff c3 66 0f 1f 44 00 00 83 3d 59 c7 20 00 00 75 13 49 89 ca b8 2c 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 34 c3 48 83 ec 08 e8 2b f7 ff ff 48 89 04 24
 RSP: 002b:00007ffe0189b748 EFLAGS: 00000246 ORIG_RAX: 000000000000002c
 RAX: ffffffffffffffda RBX: 00000000020ca010 RCX: 00007fd67e18dc93
 RDX: 0000000000000062 RSI: 00000000020ca322 RDI: 0000000000000003
 RBP: 00007ffe0189b780 R08: 00007ffe0189b760 R09: 0000000000000014
 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000062
 R13: 00000000020ca322 R14: 00007ffe0189b760 R15: 0000000000000003
 Modules linked in: act_tunnel_key act_gact cls_flower sch_ingress vrf veth act_csum(E) xt_CHECKSUM iptable_mangle ipt_MASQUERADE iptable_nat nf_nat_ipv4 nf_nat nf_conntrack_ipv4 nf_defrag_ipv4 xt_conntrack nf_conntrack ipt_REJECT nf_reject_ipv4 tun bridge stp llc ebtable_filter ebtables ip6table_filter ip6_tables iptable_filter intel_rapl snd_hda_codec_hdmi x86_pkg_temp_thermal intel_powerclamp snd_hda_codec_realtek coretemp snd_hda_codec_generic kvm_intel kvm irqbypass snd_hda_intel crct10dif_pclmul crc32_pclmul hp_wmi ghash_clmulni_intel pcbc snd_hda_codec aesni_intel sparse_keymap rfkill snd_hda_core snd_hwdep snd_seq crypto_simd iTCO_wdt gpio_ich iTCO_vendor_support wmi_bmof cryptd mei_wdt glue_helper snd_seq_device snd_pcm pcspkr snd_timer snd i2c_i801 lpc_ich sg soundcore wmi mei_me
 
  mei ie31200_edac nfsd auth_rpcgss nfs_acl lockd grace sunrpc ip_tables xfs libcrc32c sd_mod sr_mod cdrom i915 video i2c_algo_bit drm_kms_helper syscopyarea sysfillrect sysimgblt fb_sys_fops ahci crc32c_intel libahci serio_raw sfc libata mtd drm ixgbe mdio i2c_core e1000e dca
 CR2: 0000000000000000
 ---[ end trace 1ab8b5b5d4639dfc ]---
 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:ffff95145ea03c40 EFLAGS: 00010246
 RAX: 0000000020000001 RBX: ffff9514499e5800 RCX: 0000000000000001
 RDX: 0000000000000000 RSI: 0000000000000002 RDI: 0000000000000000
 RBP: ffff95145ea03e60 R08: 0000000000000000 R09: ffff95145ea03c9c
 R10: ffff95145ea03c78 R11: 0000000000000008 R12: ffff951456a69800
 R13: ffff951456a69808 R14: 0000000000000001 R15: ffff95144965ee40
 FS:  00007fd67ee11740(0000) GS:ffff95145ea00000(0000) knlGS:0000000000000000
 CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
 CR2: 0000000000000000 CR3: 00000001038a2006 CR4: 00000000001606f0
 Kernel panic - not syncing: Fatal exception in interrupt
 Kernel Offset: 0x11400000 from 0xffffffff81000000 (relocation range: 0xffffffff80000000-0xffffffffbfffffff)
 ---[ end Kernel panic - not syncing: Fatal exception in interrupt ]---

Fixes: d0f6dd8a914f ("net/sched: Introduce act_tunnel_key")
Signed-off-by: Davide Caratti <dcaratti@redhat.com>
---
 include/net/tc_act/tc_tunnel_key.h | 1 -
 net/sched/act_tunnel_key.c         | 6 +++---
 2 files changed, 3 insertions(+), 4 deletions(-)

diff --git a/include/net/tc_act/tc_tunnel_key.h b/include/net/tc_act/tc_tunnel_key.h
index efef0b4b1b2b..46b8c7f1c8d5 100644
--- a/include/net/tc_act/tc_tunnel_key.h
+++ b/include/net/tc_act/tc_tunnel_key.h
@@ -18,7 +18,6 @@
 struct tcf_tunnel_key_params {
 	struct rcu_head		rcu;
 	int			tcft_action;
-	int			action;
 	struct metadata_dst     *tcft_enc_metadata;
 };
 
diff --git a/net/sched/act_tunnel_key.c b/net/sched/act_tunnel_key.c
index 626dac81a48a..9bc6c2ae98a5 100644
--- a/net/sched/act_tunnel_key.c
+++ b/net/sched/act_tunnel_key.c
@@ -36,7 +36,7 @@ static int tunnel_key_act(struct sk_buff *skb, const struct tc_action *a,
 
 	tcf_lastuse_update(&t->tcf_tm);
 	bstats_cpu_update(this_cpu_ptr(t->common.cpu_bstats), skb);
-	action = params->action;
+	action = READ_ONCE(t->tcf_action);
 
 	switch (params->tcft_action) {
 	case TCA_TUNNEL_KEY_ACT_RELEASE:
@@ -182,7 +182,7 @@ static int tunnel_key_init(struct net *net, struct nlattr *nla,
 
 	params_old = rtnl_dereference(t->params);
 
-	params_new->action = parm->action;
+	t->tcf_action = parm->action;
 	params_new->tcft_action = parm->t_action;
 	params_new->tcft_enc_metadata = metadata;
 
@@ -254,13 +254,13 @@ static int tunnel_key_dump(struct sk_buff *skb, struct tc_action *a,
 		.index    = t->tcf_index,
 		.refcnt   = t->tcf_refcnt - ref,
 		.bindcnt  = t->tcf_bindcnt - bind,
+		.action   = t->tcf_action,
 	};
 	struct tcf_t tm;
 
 	params = rtnl_dereference(t->params);
 
 	opt.t_action = params->tcft_action;
-	opt.action = params->action;
 
 	if (nla_put(skb, TCA_TUNNEL_KEY_PARMS, sizeof(opt), &opt))
 		goto nla_put_failure;
-- 
2.17.1

Re: [PATCH net 0/2] net/sched: fix NULL dereference in 'goto chain' control action

[David Miller]

From: Davide Caratti <dcaratti@redhat.com>
Date: Fri,  6 Jul 2018 21:01:04 +0200

> in a couple of TC actions (i.e. csum and tunnel_key), the control action
> is stored together with the action-specific configuration data.
> This avoids a race condition (see [1]), but it causes a crash when 'goto
> chain' is used with the above actions. Since this race condition is
> tolerated on the other TC actions (it's present even on actions where the
> spinlock is still used), storing the control action in the common area
> should be acceptable for tunnel_key and csum as well.
> 
> [1] https://www.spinics.net/lists/netdev/msg472047.html

Series applied and queued up for -stable, thanks Davide.