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linux-stable/include/linux/virtio_net.h
Eric Dumazet 9181d6f8a2 net: add more sanity check in virtio_net_hdr_to_skb() 
syzbot/KMSAN reports access to uninitialized data from gso_features_check() [1]

The repro use af_packet, injecting a gso packet and hdrlen == 0.

We could fix the issue making gso_features_check() more careful
while dealing with NETIF_F_TSO_MANGLEID in fast path.

Or we can make sure virtio_net_hdr_to_skb() pulls minimal network and
transport headers as intended.

Note that for GSO packets coming from untrusted sources, SKB_GSO_DODGY
bit forces a proper header validation (and pull) before the packet can
hit any device ndo_start_xmit(), thus we do not need a precise disection
at virtio_net_hdr_to_skb() stage.

[1]
BUG: KMSAN: uninit-value in skb_gso_segment include/net/gso.h:83 [inline]
BUG: KMSAN: uninit-value in validate_xmit_skb+0x10f2/0x1930 net/core/dev.c:3629
 skb_gso_segment include/net/gso.h:83 [inline]
 validate_xmit_skb+0x10f2/0x1930 net/core/dev.c:3629
 __dev_queue_xmit+0x1eac/0x5130 net/core/dev.c:4341
 dev_queue_xmit include/linux/netdevice.h:3134 [inline]
 packet_xmit+0x9c/0x6b0 net/packet/af_packet.c:276
 packet_snd net/packet/af_packet.c:3087 [inline]
 packet_sendmsg+0x8b1d/0x9f30 net/packet/af_packet.c:3119
 sock_sendmsg_nosec net/socket.c:730 [inline]
 __sock_sendmsg net/socket.c:745 [inline]
 ____sys_sendmsg+0x9c2/0xd60 net/socket.c:2584
 ___sys_sendmsg+0x28d/0x3c0 net/socket.c:2638
 __sys_sendmsg net/socket.c:2667 [inline]
 __do_sys_sendmsg net/socket.c:2676 [inline]
 __se_sys_sendmsg net/socket.c:2674 [inline]
 __x64_sys_sendmsg+0x307/0x490 net/socket.c:2674
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0x44/0x110 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

Uninit was created at:
 slab_post_alloc_hook+0x129/0xa70 mm/slab.h:768
 slab_alloc_node mm/slub.c:3478 [inline]
 kmem_cache_alloc_node+0x5e9/0xb10 mm/slub.c:3523
 kmalloc_reserve+0x13d/0x4a0 net/core/skbuff.c:560
 __alloc_skb+0x318/0x740 net/core/skbuff.c:651
 alloc_skb include/linux/skbuff.h:1286 [inline]
 alloc_skb_with_frags+0xc8/0xbd0 net/core/skbuff.c:6334
 sock_alloc_send_pskb+0xa80/0xbf0 net/core/sock.c:2780
 packet_alloc_skb net/packet/af_packet.c:2936 [inline]
 packet_snd net/packet/af_packet.c:3030 [inline]
 packet_sendmsg+0x70e8/0x9f30 net/packet/af_packet.c:3119
 sock_sendmsg_nosec net/socket.c:730 [inline]
 __sock_sendmsg net/socket.c:745 [inline]
 ____sys_sendmsg+0x9c2/0xd60 net/socket.c:2584
 ___sys_sendmsg+0x28d/0x3c0 net/socket.c:2638
 __sys_sendmsg net/socket.c:2667 [inline]
 __do_sys_sendmsg net/socket.c:2676 [inline]
 __se_sys_sendmsg net/socket.c:2674 [inline]
 __x64_sys_sendmsg+0x307/0x490 net/socket.c:2674
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0x44/0x110 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

CPU: 0 PID: 5025 Comm: syz-executor279 Not tainted 6.7.0-rc7-syzkaller-00003-gfbafc3e621c3 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/17/2023

Reported-by: syzbot+7f4d0ea3df4d4fa9a65f@syzkaller.appspotmail.com
Link: https://lore.kernel.org/netdev/0000000000005abd7b060eb160cd@google.com/
Fixes: 9274124f023b ("net: stricter validation of untrusted gso packets")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Willem de Bruijn <willemb@google.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2024-01-13 18:06:23 +00:00

238 lines
6.3 KiB
C
Raw Blame History

/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _LINUX_VIRTIO_NET_H
#define _LINUX_VIRTIO_NET_H
#include <linux/if_vlan.h>
#include <linux/ip.h>
#include <linux/ipv6.h>
#include <linux/udp.h>
#include <uapi/linux/tcp.h>
#include <uapi/linux/virtio_net.h>
static inline bool virtio_net_hdr_match_proto(__be16 protocol, __u8 gso_type)
{
switch (gso_type & ~VIRTIO_NET_HDR_GSO_ECN) {
case VIRTIO_NET_HDR_GSO_TCPV4:
return protocol == cpu_to_be16(ETH_P_IP);
case VIRTIO_NET_HDR_GSO_TCPV6:
return protocol == cpu_to_be16(ETH_P_IPV6);
case VIRTIO_NET_HDR_GSO_UDP:
case VIRTIO_NET_HDR_GSO_UDP_L4:
return protocol == cpu_to_be16(ETH_P_IP) ||
protocol == cpu_to_be16(ETH_P_IPV6);
default:
return false;
}
}
static inline int virtio_net_hdr_set_proto(struct sk_buff *skb,
const struct virtio_net_hdr *hdr)
{
if (skb->protocol)
return 0;
switch (hdr->gso_type & ~VIRTIO_NET_HDR_GSO_ECN) {
case VIRTIO_NET_HDR_GSO_TCPV4:
case VIRTIO_NET_HDR_GSO_UDP:
case VIRTIO_NET_HDR_GSO_UDP_L4:
skb->protocol = cpu_to_be16(ETH_P_IP);
break;
case VIRTIO_NET_HDR_GSO_TCPV6:
skb->protocol = cpu_to_be16(ETH_P_IPV6);
break;
default:
return -EINVAL;
}
return 0;
}
static inline int virtio_net_hdr_to_skb(struct sk_buff *skb,
const struct virtio_net_hdr *hdr,
bool little_endian)
{
unsigned int nh_min_len = sizeof(struct iphdr);
unsigned int gso_type = 0;
unsigned int thlen = 0;
unsigned int p_off = 0;
unsigned int ip_proto;
if (hdr->gso_type != VIRTIO_NET_HDR_GSO_NONE) {
switch (hdr->gso_type & ~VIRTIO_NET_HDR_GSO_ECN) {
case VIRTIO_NET_HDR_GSO_TCPV4:
gso_type = SKB_GSO_TCPV4;
ip_proto = IPPROTO_TCP;
thlen = sizeof(struct tcphdr);
break;
case VIRTIO_NET_HDR_GSO_TCPV6:
gso_type = SKB_GSO_TCPV6;
ip_proto = IPPROTO_TCP;
thlen = sizeof(struct tcphdr);
nh_min_len = sizeof(struct ipv6hdr);
break;
case VIRTIO_NET_HDR_GSO_UDP:
gso_type = SKB_GSO_UDP;
ip_proto = IPPROTO_UDP;
thlen = sizeof(struct udphdr);
break;
case VIRTIO_NET_HDR_GSO_UDP_L4:
gso_type = SKB_GSO_UDP_L4;
ip_proto = IPPROTO_UDP;
thlen = sizeof(struct udphdr);
break;
default:
return -EINVAL;
}
if (hdr->gso_type & VIRTIO_NET_HDR_GSO_ECN)
gso_type |= SKB_GSO_TCP_ECN;
if (hdr->gso_size == 0)
return -EINVAL;
}
skb_reset_mac_header(skb);
if (hdr->flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) {
u32 start = __virtio16_to_cpu(little_endian, hdr->csum_start);
u32 off = __virtio16_to_cpu(little_endian, hdr->csum_offset);
u32 needed = start + max_t(u32, thlen, off + sizeof(__sum16));
if (!pskb_may_pull(skb, needed))
return -EINVAL;
if (!skb_partial_csum_set(skb, start, off))
return -EINVAL;
nh_min_len = max_t(u32, nh_min_len, skb_transport_offset(skb));
p_off = nh_min_len + thlen;
if (!pskb_may_pull(skb, p_off))
return -EINVAL;
} else {
/* gso packets without NEEDS_CSUM do not set transport_offset.
* probe and drop if does not match one of the above types.
*/
if (gso_type && skb->network_header) {
struct flow_keys_basic keys;
if (!skb->protocol) {
__be16 protocol = dev_parse_header_protocol(skb);
if (!protocol)
virtio_net_hdr_set_proto(skb, hdr);
else if (!virtio_net_hdr_match_proto(protocol, hdr->gso_type))
return -EINVAL;
else
skb->protocol = protocol;
}
retry:
if (!skb_flow_dissect_flow_keys_basic(NULL, skb, &keys,
NULL, 0, 0, 0,
0)) {
/* UFO does not specify ipv4 or 6: try both */
if (gso_type & SKB_GSO_UDP &&
skb->protocol == htons(ETH_P_IP)) {
skb->protocol = htons(ETH_P_IPV6);
goto retry;
}
return -EINVAL;
}
p_off = keys.control.thoff + thlen;
if (!pskb_may_pull(skb, p_off) ||
keys.basic.ip_proto != ip_proto)
return -EINVAL;
skb_set_transport_header(skb, keys.control.thoff);
} else if (gso_type) {
p_off = nh_min_len + thlen;
if (!pskb_may_pull(skb, p_off))
return -EINVAL;
}
}
if (hdr->gso_type != VIRTIO_NET_HDR_GSO_NONE) {
u16 gso_size = __virtio16_to_cpu(little_endian, hdr->gso_size);
unsigned int nh_off = p_off;
struct skb_shared_info *shinfo = skb_shinfo(skb);
switch (gso_type & ~SKB_GSO_TCP_ECN) {
case SKB_GSO_UDP:
/* UFO may not include transport header in gso_size. */
nh_off -= thlen;
break;
case SKB_GSO_UDP_L4:
if (!(hdr->flags & VIRTIO_NET_HDR_F_NEEDS_CSUM))
return -EINVAL;
if (skb->csum_offset != offsetof(struct udphdr, check))
return -EINVAL;
if (skb->len - p_off > gso_size * UDP_MAX_SEGMENTS)
return -EINVAL;
if (gso_type != SKB_GSO_UDP_L4)
return -EINVAL;
break;
}
/* Kernel has a special handling for GSO_BY_FRAGS. */
if (gso_size == GSO_BY_FRAGS)
return -EINVAL;
/* Too small packets are not really GSO ones. */
if (skb->len - nh_off > gso_size) {
shinfo->gso_size = gso_size;
shinfo->gso_type = gso_type;
/* Header must be checked, and gso_segs computed. */
shinfo->gso_type |= SKB_GSO_DODGY;
shinfo->gso_segs = 0;
}
}
return 0;
}
static inline int virtio_net_hdr_from_skb(const struct sk_buff *skb,
struct virtio_net_hdr *hdr,
bool little_endian,
bool has_data_valid,
int vlan_hlen)
{
memset(hdr, 0, sizeof(*hdr)); /* no info leak */
if (skb_is_gso(skb)) {
struct skb_shared_info *sinfo = skb_shinfo(skb);
/* This is a hint as to how much should be linear. */
hdr->hdr_len = __cpu_to_virtio16(little_endian,
skb_headlen(skb));
hdr->gso_size = __cpu_to_virtio16(little_endian,
sinfo->gso_size);
if (sinfo->gso_type & SKB_GSO_TCPV4)
hdr->gso_type = VIRTIO_NET_HDR_GSO_TCPV4;
else if (sinfo->gso_type & SKB_GSO_TCPV6)
hdr->gso_type = VIRTIO_NET_HDR_GSO_TCPV6;
else if (sinfo->gso_type & SKB_GSO_UDP_L4)
hdr->gso_type = VIRTIO_NET_HDR_GSO_UDP_L4;
else
return -EINVAL;
if (sinfo->gso_type & SKB_GSO_TCP_ECN)
hdr->gso_type |= VIRTIO_NET_HDR_GSO_ECN;
} else
hdr->gso_type = VIRTIO_NET_HDR_GSO_NONE;
if (skb->ip_summed == CHECKSUM_PARTIAL) {
hdr->flags = VIRTIO_NET_HDR_F_NEEDS_CSUM;
hdr->csum_start = __cpu_to_virtio16(little_endian,
skb_checksum_start_offset(skb) + vlan_hlen);
hdr->csum_offset = __cpu_to_virtio16(little_endian,
skb->csum_offset);
} else if (has_data_valid &&
skb->ip_summed == CHECKSUM_UNNECESSARY) {
hdr->flags = VIRTIO_NET_HDR_F_DATA_VALID;
} /* else everything is zero */
return 0;
}
#endif /* _LINUX_VIRTIO_NET_H */
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