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[PACKET]: Fix skb->cb clobbering between aux and sockaddr 

Both aux data and sockaddr tries to use the same buffer which
obviously doesn't work.  We just happen to have 4 bytes free in
the skb->cb if you take away the maximum length of sockaddr_ll.
That's just enough to store the one piece of info from aux data
that we can't generate at recvmsg(2) time.

This is what the following patch does.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Herbert Xu 2007-02-04 23:33:10 -08:00 committed by David S. Miller
parent 8dc4194474
commit ffbc61117d
1 changed files with 30 additions and 16 deletions
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46
net/packet/af_packet.c
View File

@ -60,6 +60,7 @@
#include <linux/netdevice.h>
#include <linux/if_packet.h>
#include <linux/wireless.h>
#include <linux/kernel.h>
#include <linux/kmod.h>
#include <net/ip.h>
#include <net/protocol.h>
@ -215,7 +216,15 @@ struct packet_sock {
#endif
};
#define PACKET_SKB_CB(__skb) ((struct tpacket_auxdata *)((__skb)->cb))
struct packet_skb_cb {
unsigned int origlen;
union {
struct sockaddr_pkt pkt;
struct sockaddr_ll ll;
} sa;
};
#define PACKET_SKB_CB(__skb) ((struct packet_skb_cb *)((__skb)->cb))
#ifdef CONFIG_PACKET_MMAP
@ -296,7 +305,7 @@ static int packet_rcv_spkt(struct sk_buff *skb, struct net_device *dev, struct
/* drop conntrack reference */
nf_reset(skb);
spkt = (struct sockaddr_pkt*)skb->cb;
spkt = &PACKET_SKB_CB(skb)->sa.pkt;
skb_push(skb, skb->data-skb->mac.raw);
@ -465,7 +474,6 @@ static int packet_rcv(struct sk_buff *skb, struct net_device *dev, struct packet
u8 * skb_head = skb->data;
int skb_len = skb->len;
unsigned int snaplen, res;
struct tpacket_auxdata *aux;
if (skb->pkt_type == PACKET_LOOPBACK)
goto drop;
@ -516,7 +524,10 @@ static int packet_rcv(struct sk_buff *skb, struct net_device *dev, struct packet
skb = nskb;
}
sll = (struct sockaddr_ll*)skb->cb;
BUILD_BUG_ON(sizeof(*PACKET_SKB_CB(skb)) + MAX_ADDR_LEN - 8 >
sizeof(skb->cb));
sll = &PACKET_SKB_CB(skb)->sa.ll;
sll->sll_family = AF_PACKET;
sll->sll_hatype = dev->type;
sll->sll_protocol = skb->protocol;
@ -527,14 +538,7 @@ static int packet_rcv(struct sk_buff *skb, struct net_device *dev, struct packet
if (dev->hard_header_parse)
sll->sll_halen = dev->hard_header_parse(skb, sll->sll_addr);
aux = PACKET_SKB_CB(skb);
aux->tp_status = TP_STATUS_USER;
if (skb->ip_summed == CHECKSUM_PARTIAL)
aux->tp_status |= TP_STATUS_CSUMNOTREADY;
aux->tp_len = skb->len;
aux->tp_snaplen = snaplen;
aux->tp_mac = 0;
aux->tp_net = skb->nh.raw - skb->data;
PACKET_SKB_CB(skb)->origlen = skb->len;
if (pskb_trim(skb, snaplen))
goto drop_n_acct;
@ -1106,7 +1110,7 @@ static int packet_recvmsg(struct kiocb *iocb, struct socket *sock,
* it in now.
*/
sll = (struct sockaddr_ll*)skb->cb;
sll = &PACKET_SKB_CB(skb)->sa.ll;
if (sock->type == SOCK_PACKET)
msg->msg_namelen = sizeof(struct sockaddr_pkt);
else
@ -1131,11 +1135,21 @@ static int packet_recvmsg(struct kiocb *iocb, struct socket *sock,
sock_recv_timestamp(msg, sk, skb);
if (msg->msg_name)
memcpy(msg->msg_name, skb->cb, msg->msg_namelen);
memcpy(msg->msg_name, &PACKET_SKB_CB(skb)->sa,
msg->msg_namelen);
if (pkt_sk(sk)->auxdata) {
struct tpacket_auxdata *aux = PACKET_SKB_CB(skb);
put_cmsg(msg, SOL_PACKET, PACKET_AUXDATA, sizeof(*aux), aux);
struct tpacket_auxdata aux;
aux.tp_status = TP_STATUS_USER;
if (skb->ip_summed == CHECKSUM_PARTIAL)
aux.tp_status |= TP_STATUS_CSUMNOTREADY;
aux.tp_len = PACKET_SKB_CB(skb)->origlen;
aux.tp_snaplen = skb->len;
aux.tp_mac = 0;
aux.tp_net = skb->nh.raw - skb->data;
put_cmsg(msg, SOL_PACKET, PACKET_AUXDATA, sizeof(aux), &aux);
}
/*