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qemu/include/net/net.h
Jason Wang 25c01bd19d net: drop too large packet early 
We try to detect and drop too large packet (>INT_MAX) in 1592a99470
("net: ignore packet size greater than INT_MAX") during packet
delivering. Unfortunately, this is not sufficient as we may hit
another integer overflow when trying to queue such large packet in
qemu_net_queue_append_iov():

- size of the allocation may overflow on 32bit
- packet->size is integer which may overflow even on 64bit

Fixing this by moving the check to qemu_sendv_packet_async() which is
the entrance of all networking codes and reduce the limit to
NET_BUFSIZE to be more conservative. This works since:

- For the callers that call qemu_sendv_packet_async() directly, they
  only care about if zero is returned to determine whether to prevent
  the source from producing more packets. A callback will be triggered
  if peer can accept more then source could be enabled. This is
  usually used by high speed networking implementation like virtio-net
  or netmap.
- For the callers that call qemu_sendv_packet() that calls
  qemu_sendv_packet_async() indirectly, they often ignore the return
  value. In this case qemu will just the drop packets if peer can't
  receive.

Qemu will copy the packet if it was queued. So it was safe for both
kinds of the callers to assume the packet was sent.

Since we move the check from qemu_deliver_packet_iov() to
qemu_sendv_packet_async(), it would be safer to make
qemu_deliver_packet_iov() static to prevent any external user in the
future.

This is a revised patch of CVE-2018-17963.

Cc: qemu-stable@nongnu.org
Cc: Li Qiang <liq3ea@163.com>
Fixes: 1592a99470 ("net: ignore packet size greater than INT_MAX")
Reported-by: Li Qiang <liq3ea@gmail.com>
Reviewed-by: Li Qiang <liq3ea@gmail.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Message-id: 20181204035347.6148-2-jasowang@redhat.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
2018-12-04 11:06:15 +00:00

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#ifndef QEMU_NET_H
#define QEMU_NET_H
#include "qemu/queue.h"
#include "qapi/qapi-types-net.h"
#include "net/queue.h"
#include "migration/vmstate.h"
#define MAC_FMT "%02X:%02X:%02X:%02X:%02X:%02X"
#define MAC_ARG(x) ((uint8_t *)(x))[0], ((uint8_t *)(x))[1], \
((uint8_t *)(x))[2], ((uint8_t *)(x))[3], \
((uint8_t *)(x))[4], ((uint8_t *)(x))[5]
#define MAX_QUEUE_NUM 1024
/* Maximum GSO packet size (64k) plus plenty of room for
* the ethernet and virtio_net headers
*/
#define NET_BUFSIZE (4096 + 65536)
struct MACAddr {
uint8_t a[6];
};
/* qdev nic properties */
typedef struct NICPeers {
NetClientState *ncs[MAX_QUEUE_NUM];
int32_t queues;
} NICPeers;
typedef struct NICConf {
MACAddr macaddr;
NICPeers peers;
int32_t bootindex;
} NICConf;
#define DEFINE_NIC_PROPERTIES(_state, _conf) \
DEFINE_PROP_MACADDR("mac", _state, _conf.macaddr), \
DEFINE_PROP_NETDEV("netdev", _state, _conf.peers)
/* Net clients */
typedef void (NetPoll)(NetClientState *, bool enable);
typedef int (NetCanReceive)(NetClientState *);
typedef ssize_t (NetReceive)(NetClientState *, const uint8_t *, size_t);
typedef ssize_t (NetReceiveIOV)(NetClientState *, const struct iovec *, int);
typedef void (NetCleanup) (NetClientState *);
typedef void (LinkStatusChanged)(NetClientState *);
typedef void (NetClientDestructor)(NetClientState *);
typedef RxFilterInfo *(QueryRxFilter)(NetClientState *);
typedef bool (HasUfo)(NetClientState *);
typedef bool (HasVnetHdr)(NetClientState *);
typedef bool (HasVnetHdrLen)(NetClientState *, int);
typedef void (UsingVnetHdr)(NetClientState *, bool);
typedef void (SetOffload)(NetClientState *, int, int, int, int, int);
typedef void (SetVnetHdrLen)(NetClientState *, int);
typedef int (SetVnetLE)(NetClientState *, bool);
typedef int (SetVnetBE)(NetClientState *, bool);
typedef struct SocketReadState SocketReadState;
typedef void (SocketReadStateFinalize)(SocketReadState *rs);
typedef struct NetClientInfo {
NetClientDriver type;
size_t size;
NetReceive *receive;
NetReceive *receive_raw;
NetReceiveIOV *receive_iov;
NetCanReceive *can_receive;
NetCleanup *cleanup;
LinkStatusChanged *link_status_changed;
QueryRxFilter *query_rx_filter;
NetPoll *poll;
HasUfo *has_ufo;
HasVnetHdr *has_vnet_hdr;
HasVnetHdrLen *has_vnet_hdr_len;
UsingVnetHdr *using_vnet_hdr;
SetOffload *set_offload;
SetVnetHdrLen *set_vnet_hdr_len;
SetVnetLE *set_vnet_le;
SetVnetBE *set_vnet_be;
} NetClientInfo;
struct NetClientState {
NetClientInfo *info;
int link_down;
QTAILQ_ENTRY(NetClientState) next;
NetClientState *peer;
NetQueue *incoming_queue;
char *model;
char *name;
char info_str[256];
unsigned receive_disabled : 1;
NetClientDestructor *destructor;
unsigned int queue_index;
unsigned rxfilter_notify_enabled:1;
int vring_enable;
int vnet_hdr_len;
QTAILQ_HEAD(NetFilterHead, NetFilterState) filters;
};
typedef struct NICState {
NetClientState *ncs;
NICConf *conf;
void *opaque;
bool peer_deleted;
} NICState;
struct SocketReadState {
/* 0 = getting length, 1 = getting vnet header length, 2 = getting data */
int state;
/* This flag decide whether to read the vnet_hdr_len field */
bool vnet_hdr;
uint32_t index;
uint32_t packet_len;
uint32_t vnet_hdr_len;
uint8_t buf[NET_BUFSIZE];
SocketReadStateFinalize *finalize;
};
int net_fill_rstate(SocketReadState *rs, const uint8_t *buf, int size);
char *qemu_mac_strdup_printf(const uint8_t *macaddr);
NetClientState *qemu_find_netdev(const char *id);
int qemu_find_net_clients_except(const char *id, NetClientState **ncs,
NetClientDriver type, int max);
NetClientState *qemu_new_net_client(NetClientInfo *info,
NetClientState *peer,
const char *model,
const char *name);
NICState *qemu_new_nic(NetClientInfo *info,
NICConf *conf,
const char *model,
const char *name,
void *opaque);
void qemu_del_nic(NICState *nic);
NetClientState *qemu_get_subqueue(NICState *nic, int queue_index);
NetClientState *qemu_get_queue(NICState *nic);
NICState *qemu_get_nic(NetClientState *nc);
void *qemu_get_nic_opaque(NetClientState *nc);
void qemu_del_net_client(NetClientState *nc);
typedef void (*qemu_nic_foreach)(NICState *nic, void *opaque);
void qemu_foreach_nic(qemu_nic_foreach func, void *opaque);
int qemu_can_send_packet(NetClientState *nc);
ssize_t qemu_sendv_packet(NetClientState *nc, const struct iovec *iov,
int iovcnt);
ssize_t qemu_sendv_packet_async(NetClientState *nc, const struct iovec *iov,
int iovcnt, NetPacketSent *sent_cb);
void qemu_send_packet(NetClientState *nc, const uint8_t *buf, int size);
ssize_t qemu_send_packet_raw(NetClientState *nc, const uint8_t *buf, int size);
ssize_t qemu_send_packet_async(NetClientState *nc, const uint8_t *buf,
int size, NetPacketSent *sent_cb);
void qemu_purge_queued_packets(NetClientState *nc);
void qemu_flush_queued_packets(NetClientState *nc);
void qemu_flush_or_purge_queued_packets(NetClientState *nc, bool purge);
void qemu_format_nic_info_str(NetClientState *nc, uint8_t macaddr[6]);
bool qemu_has_ufo(NetClientState *nc);
bool qemu_has_vnet_hdr(NetClientState *nc);
bool qemu_has_vnet_hdr_len(NetClientState *nc, int len);
void qemu_using_vnet_hdr(NetClientState *nc, bool enable);
void qemu_set_offload(NetClientState *nc, int csum, int tso4, int tso6,
int ecn, int ufo);
void qemu_set_vnet_hdr_len(NetClientState *nc, int len);
int qemu_set_vnet_le(NetClientState *nc, bool is_le);
int qemu_set_vnet_be(NetClientState *nc, bool is_be);
void qemu_macaddr_default_if_unset(MACAddr *macaddr);
int qemu_show_nic_models(const char *arg, const char *const *models);
void qemu_check_nic_model(NICInfo *nd, const char *model);
int qemu_find_nic_model(NICInfo *nd, const char * const *models,
const char *default_model);
void print_net_client(Monitor *mon, NetClientState *nc);
void hmp_info_network(Monitor *mon, const QDict *qdict);
void net_socket_rs_init(SocketReadState *rs,
SocketReadStateFinalize *finalize,
bool vnet_hdr);
/* NIC info */
#define MAX_NICS 8
struct NICInfo {
MACAddr macaddr;
char *model;
char *name;
char *devaddr;
NetClientState *netdev;
int used; /* is this slot in nd_table[] being used? */
int instantiated; /* does this NICInfo correspond to an instantiated NIC? */
int nvectors;
};
extern int nb_nics;
extern NICInfo nd_table[MAX_NICS];
extern const char *host_net_devices[];
/* from net.c */
int net_client_parse(QemuOptsList *opts_list, const char *str);
int net_init_clients(Error **errp);
void net_check_clients(void);
void net_cleanup(void);
void hmp_host_net_add(Monitor *mon, const QDict *qdict);
void hmp_host_net_remove(Monitor *mon, const QDict *qdict);
void netdev_add(QemuOpts *opts, Error **errp);
void qmp_netdev_add(QDict *qdict, QObject **ret, Error **errp);
int net_hub_id_for_client(NetClientState *nc, int *id);
NetClientState *net_hub_port_find(int hub_id);
#define DEFAULT_NETWORK_SCRIPT "/etc/qemu-ifup"
#define DEFAULT_NETWORK_DOWN_SCRIPT "/etc/qemu-ifdown"
#define DEFAULT_BRIDGE_HELPER CONFIG_QEMU_HELPERDIR "/qemu-bridge-helper"
#define DEFAULT_BRIDGE_INTERFACE "br0"
void qdev_set_nic_properties(DeviceState *dev, NICInfo *nd);
#define POLYNOMIAL_BE 0x04c11db6
#define POLYNOMIAL_LE 0xedb88320
uint32_t net_crc32(const uint8_t *p, int len);
uint32_t net_crc32_le(const uint8_t *p, int len);
#define vmstate_offset_macaddr(_state, _field) \
vmstate_offset_array(_state, _field.a, uint8_t, \
sizeof(typeof_field(_state, _field)))
#define VMSTATE_MACADDR(_field, _state) { \
.name = (stringify(_field)), \
.size = sizeof(MACAddr), \
.info = &vmstate_info_buffer, \
.flags = VMS_BUFFER, \
.offset = vmstate_offset_macaddr(_state, _field), \
}
#endif
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