If an AF_PACKET socket is used to send packets through ipvlan and the
default xmit function of the AF_PACKET socket is changed from
dev_queue_xmit() to packet_direct_xmit() via setsockopt() with the option
name of PACKET_QDISC_BYPASS, the skb->mac_header may not be reset and
remains as the initial value of 65535, this may trigger slab-out-of-bounds
bugs as following:
=================================================================
UG: KASAN: slab-out-of-bounds in ipvlan_xmit_mode_l2+0xdb/0x330 [ipvlan]
PU: 2 PID: 1768 Comm: raw_send Kdump: loaded Not tainted 6.0.0-rc4+ #6
ardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.14.0-1.fc33
all Trace:
print_address_description.constprop.0+0x1d/0x160
print_report.cold+0x4f/0x112
kasan_report+0xa3/0x130
ipvlan_xmit_mode_l2+0xdb/0x330 [ipvlan]
ipvlan_start_xmit+0x29/0xa0 [ipvlan]
__dev_direct_xmit+0x2e2/0x380
packet_direct_xmit+0x22/0x60
packet_snd+0x7c9/0xc40
sock_sendmsg+0x9a/0xa0
__sys_sendto+0x18a/0x230
__x64_sys_sendto+0x74/0x90
do_syscall_64+0x3b/0x90
entry_SYSCALL_64_after_hwframe+0x63/0xcd
The root cause is:
1. packet_snd() only reset skb->mac_header when sock->type is SOCK_RAW
and skb->protocol is not specified as in packet_parse_headers()
2. packet_direct_xmit() doesn't reset skb->mac_header as dev_queue_xmit()
In this case, skb->mac_header is 65535 when ipvlan_xmit_mode_l2() is
called. So when ipvlan_xmit_mode_l2() gets mac header with eth_hdr() which
use "skb->head + skb->mac_header", out-of-bound access occurs.
This patch replaces eth_hdr() with skb_eth_hdr() in ipvlan_xmit_mode_l2()
and reset mac header in multicast to solve this out-of-bound bug.
Fixes: 2ad7bf363841 ("ipvlan: Initial check-in of the IPVLAN driver.")
Signed-off-by: Lu Wei <[email protected]>
---
drivers/net/ipvlan/ipvlan_core.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/drivers/net/ipvlan/ipvlan_core.c b/drivers/net/ipvlan/ipvlan_core.c
index dfeb5b392e64..bb1c298c1e78 100644
--- a/drivers/net/ipvlan/ipvlan_core.c
+++ b/drivers/net/ipvlan/ipvlan_core.c
@@ -495,7 +495,6 @@ static int ipvlan_process_v6_outbound(struct sk_buff *skb)
static int ipvlan_process_outbound(struct sk_buff *skb)
{
- struct ethhdr *ethh = eth_hdr(skb);
int ret = NET_XMIT_DROP;
/* The ipvlan is a pseudo-L2 device, so the packets that we receive
@@ -505,6 +504,8 @@ static int ipvlan_process_outbound(struct sk_buff *skb)
if (skb_mac_header_was_set(skb)) {
/* In this mode we dont care about
* multicast and broadcast traffic */
+ struct ethhdr *ethh = eth_hdr(skb);
+
if (is_multicast_ether_addr(ethh->h_dest)) {
pr_debug_ratelimited(
"Dropped {multi|broad}cast of type=[%x]\n",
@@ -589,7 +590,7 @@ static int ipvlan_xmit_mode_l3(struct sk_buff *skb, struct net_device *dev)
static int ipvlan_xmit_mode_l2(struct sk_buff *skb, struct net_device *dev)
{
const struct ipvl_dev *ipvlan = netdev_priv(dev);
- struct ethhdr *eth = eth_hdr(skb);
+ struct ethhdr *eth = skb_eth_hdr(skb);
struct ipvl_addr *addr;
void *lyr3h;
int addr_type;
@@ -619,6 +620,7 @@ static int ipvlan_xmit_mode_l2(struct sk_buff *skb, struct net_device *dev)
return dev_forward_skb(ipvlan->phy_dev, skb);
} else if (is_multicast_ether_addr(eth->h_dest)) {
+ skb_reset_mac_header(skb);
ipvlan_skb_crossing_ns(skb, NULL);
ipvlan_multicast_enqueue(ipvlan->port, skb, true);
return NET_XMIT_SUCCESS;
--
2.31.1
On Wed, Sep 7, 2022 at 3:09 AM Lu Wei <[email protected]> wrote:
>
> If an AF_PACKET socket is used to send packets through ipvlan and the
> default xmit function of the AF_PACKET socket is changed from
> dev_queue_xmit() to packet_direct_xmit() via setsockopt() with the option
> name of PACKET_QDISC_BYPASS, the skb->mac_header may not be reset and
> remains as the initial value of 65535, this may trigger slab-out-of-bounds
> bugs as following:
>
> =================================================================
> UG: KASAN: slab-out-of-bounds in ipvlan_xmit_mode_l2+0xdb/0x330 [ipvlan]
>
> Fixes: 2ad7bf363841 ("ipvlan: Initial check-in of the IPVLAN driver.")
> Signed-off-by: Lu Wei <[email protected]>
> ---
This was on my TODO list, I had a similar KASAN report, after my
recent addition in skb_mac_header()
DEBUG_NET_WARN_ON_ONCE(!skb_mac_header_was_set(skb));
Reviewed-by: Eric Dumazet <[email protected]>
WARNING: CPU: 1 PID: 14752 at include/linux/skbuff.h:2821
skb_mac_header include/linux/skbuff.h:2821 [inline]
WARNING: CPU: 1 PID: 14752 at include/linux/skbuff.h:2821 eth_hdr
include/linux/if_ether.h:24 [inline]
WARNING: CPU: 1 PID: 14752 at include/linux/skbuff.h:2821
ipvlan_xmit_mode_l2 drivers/net/ipvlan/ipvlan_core.c:592 [inline]
WARNING: CPU: 1 PID: 14752 at include/linux/skbuff.h:2821
ipvlan_queue_xmit+0xcba/0x19d0 drivers/net/ipvlan/ipvlan_core.c:644
Modules linked in:
CPU: 1 PID: 14752 Comm: syz-executor.4 Not tainted 6.0.0-rc3-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine,
BIOS Google 07/22/2022
RIP: 0010:skb_mac_header include/linux/skbuff.h:2821 [inline]
RIP: 0010:eth_hdr include/linux/if_ether.h:24 [inline]
RIP: 0010:ipvlan_xmit_mode_l2 drivers/net/ipvlan/ipvlan_core.c:592 [inline]
RIP: 0010:ipvlan_queue_xmit+0xcba/0x19d0 drivers/net/ipvlan/ipvlan_core.c:644
Code: 41 0f b7 d6 48 c7 c6 40 c7 75 8a 48 c7 c7 c0 c4 75 8a c6 05 7d
52 d9 08 01 e8 df 0d 4a 04 0f 0b e9 e5 f7 ff ff e8 66 cb 8b fc <0f> 0b
e9 ac f8 ff ff e8 6a 35 d8 fc e9 ed f4 ff ff e8 70 35 d8 fc
RSP: 0018:ffffc900069b7808 EFLAGS: 00010293
RAX: 0000000000000000 RBX: ffff8880456ea000 RCX: 0000000000000000
RDX: ffff8880214c5880 RSI: ffffffff84f03eca RDI: 0000000000000003
RBP: ffffc900069b79b8 R08: 0000000000000003 R09: 000000000000ffff
R10: 000000000000ffff R11: 0000000000000000 R12: ffff888075d62140
R13: 1ffff92000d36f06 R14: 000000000000ffff R15: ffff8880456eaca0
FS: 00007f2302712700(0000) GS:ffff8880b9b00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f23005fe718 CR3: 000000001f461000 CR4: 00000000003506e0
Call Trace:
<TASK>
ipvlan_start_xmit+0x45/0x150 drivers/net/ipvlan/ipvlan_main.c:220
__netdev_start_xmit include/linux/netdevice.h:4819 [inline]
netdev_start_xmit include/linux/netdevice.h:4833 [inline]
__dev_direct_xmit+0x500/0x720 net/core/dev.c:4312
dev_direct_xmit include/linux/netdevice.h:3021 [inline]
packet_direct_xmit+0x1b3/0x2c0 net/packet/af_packet.c:282
packet_snd net/packet/af_packet.c:3073 [inline]
packet_sendmsg+0x3354/0x5500 net/packet/af_packet.c:3104
sock_sendmsg_nosec net/socket.c:714 [inline]
sock_sendmsg+0xcf/0x120 net/socket.c:734
__sys_sendto+0x236/0x340 net/socket.c:2117
__do_sys_sendto net/socket.c:2129 [inline]
__se_sys_sendto net/socket.c:2125 [inline]
__x64_sys_sendto+0xdd/0x1b0 net/socket.c:2125
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f2301689279
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48
89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d
01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f2302712168 EFLAGS: 00000246 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 00007f230179c120 RCX: 00007f2301689279
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000003
RBP: 00007f23016e3189 R08: 00000000200000c0 R09: 0000000000000014
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f2301ccfb1f R14: 00007f2302712300 R15: 0000000000022000
</TASK>
Hello:
This patch was applied to netdev/net.git (master)
by David S. Miller <[email protected]>:
On Wed, 7 Sep 2022 18:12:04 +0800 you wrote:
> If an AF_PACKET socket is used to send packets through ipvlan and the
> default xmit function of the AF_PACKET socket is changed from
> dev_queue_xmit() to packet_direct_xmit() via setsockopt() with the option
> name of PACKET_QDISC_BYPASS, the skb->mac_header may not be reset and
> remains as the initial value of 65535, this may trigger slab-out-of-bounds
> bugs as following:
>
> [...]
Here is the summary with links:
- [net] ipvlan: Fix out-of-bound bugs caused by unset skb->mac_header
https://git.kernel.org/netdev/net/c/81225b2ea161
You are awesome, thank you!
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