From: Xie He xie.he.0141@gmail.com
[ Upstream commit 8306266c1d51aac9aa7aa907fe99032a58c6382c ]
The fr_hard_header function is used to prepend the header to skbs before transmission. It is used in 3 situations: 1) When a control packet is generated internally in this driver; 2) When a user sends an skb on an Ethernet-emulating PVC device; 3) When a user sends an skb on a normal PVC device.
These 3 situations need to be handled differently by fr_hard_header. Different headers should be prepended to the skb in different situations.
Currently fr_hard_header distinguishes these 3 situations using skb->protocol. For situation 1 and 2, a special skb->protocol value will be assigned before calling fr_hard_header, so that it can recognize these 2 situations. All skb->protocol values other than these special ones are treated by fr_hard_header as situation 3.
However, it is possible that in situation 3, the user sends an skb with one of the special skb->protocol values. In this case, fr_hard_header would incorrectly treat it as situation 1 or 2.
This patch tries to solve this issue by using skb->dev instead of skb->protocol to distinguish between these 3 situations. For situation 1, skb->dev would be NULL; for situation 2, skb->dev->type would be ARPHRD_ETHER; and for situation 3, skb->dev->type would be ARPHRD_DLCI.
This way fr_hard_header would be able to distinguish these 3 situations correctly regardless what skb->protocol value the user tries to use in situation 3.
Cc: Krzysztof Halasa khc@pm.waw.pl Signed-off-by: Xie He xie.he.0141@gmail.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/net/wan/hdlc_fr.c | 98 ++++++++++++++++++++------------------- 1 file changed, 51 insertions(+), 47 deletions(-)
diff --git a/drivers/net/wan/hdlc_fr.c b/drivers/net/wan/hdlc_fr.c index bba19d068207a..487605d2b389d 100644 --- a/drivers/net/wan/hdlc_fr.c +++ b/drivers/net/wan/hdlc_fr.c @@ -275,63 +275,69 @@ static inline struct net_device **get_dev_p(struct pvc_device *pvc,
static int fr_hard_header(struct sk_buff **skb_p, u16 dlci) { - u16 head_len; struct sk_buff *skb = *skb_p;
- switch (skb->protocol) { - case cpu_to_be16(NLPID_CCITT_ANSI_LMI): - head_len = 4; - skb_push(skb, head_len); - skb->data[3] = NLPID_CCITT_ANSI_LMI; - break; - - case cpu_to_be16(NLPID_CISCO_LMI): - head_len = 4; - skb_push(skb, head_len); - skb->data[3] = NLPID_CISCO_LMI; - break; - - case cpu_to_be16(ETH_P_IP): - head_len = 4; - skb_push(skb, head_len); - skb->data[3] = NLPID_IP; - break; - - case cpu_to_be16(ETH_P_IPV6): - head_len = 4; - skb_push(skb, head_len); - skb->data[3] = NLPID_IPV6; - break; - - case cpu_to_be16(ETH_P_802_3): - head_len = 10; - if (skb_headroom(skb) < head_len) { - struct sk_buff *skb2 = skb_realloc_headroom(skb, - head_len); + if (!skb->dev) { /* Control packets */ + switch (dlci) { + case LMI_CCITT_ANSI_DLCI: + skb_push(skb, 4); + skb->data[3] = NLPID_CCITT_ANSI_LMI; + break; + + case LMI_CISCO_DLCI: + skb_push(skb, 4); + skb->data[3] = NLPID_CISCO_LMI; + break; + + default: + return -EINVAL; + } + + } else if (skb->dev->type == ARPHRD_DLCI) { + switch (skb->protocol) { + case htons(ETH_P_IP): + skb_push(skb, 4); + skb->data[3] = NLPID_IP; + break; + + case htons(ETH_P_IPV6): + skb_push(skb, 4); + skb->data[3] = NLPID_IPV6; + break; + + default: + skb_push(skb, 10); + skb->data[3] = FR_PAD; + skb->data[4] = NLPID_SNAP; + /* OUI 00-00-00 indicates an Ethertype follows */ + skb->data[5] = 0x00; + skb->data[6] = 0x00; + skb->data[7] = 0x00; + /* This should be an Ethertype: */ + *(__be16 *)(skb->data + 8) = skb->protocol; + } + + } else if (skb->dev->type == ARPHRD_ETHER) { + if (skb_headroom(skb) < 10) { + struct sk_buff *skb2 = skb_realloc_headroom(skb, 10); if (!skb2) return -ENOBUFS; dev_kfree_skb(skb); skb = *skb_p = skb2; } - skb_push(skb, head_len); + skb_push(skb, 10); skb->data[3] = FR_PAD; skb->data[4] = NLPID_SNAP; - skb->data[5] = FR_PAD; + /* OUI 00-80-C2 stands for the 802.1 organization */ + skb->data[5] = 0x00; skb->data[6] = 0x80; skb->data[7] = 0xC2; + /* PID 00-07 stands for Ethernet frames without FCS */ skb->data[8] = 0x00; - skb->data[9] = 0x07; /* bridged Ethernet frame w/out FCS */ - break; + skb->data[9] = 0x07;
- default: - head_len = 10; - skb_push(skb, head_len); - skb->data[3] = FR_PAD; - skb->data[4] = NLPID_SNAP; - skb->data[5] = FR_PAD; - skb->data[6] = FR_PAD; - skb->data[7] = FR_PAD; - *(__be16*)(skb->data + 8) = skb->protocol; + } else { + return -EINVAL; }
dlci_to_q922(skb->data, dlci); @@ -427,8 +433,8 @@ static netdev_tx_t pvc_xmit(struct sk_buff *skb, struct net_device *dev) skb_put(skb, pad); memset(skb->data + len, 0, pad); } - skb->protocol = cpu_to_be16(ETH_P_802_3); } + skb->dev = dev; if (!fr_hard_header(&skb, pvc->dlci)) { dev->stats.tx_bytes += skb->len; dev->stats.tx_packets++; @@ -496,10 +502,8 @@ static void fr_lmi_send(struct net_device *dev, int fullrep) memset(skb->data, 0, len); skb_reserve(skb, 4); if (lmi == LMI_CISCO) { - skb->protocol = cpu_to_be16(NLPID_CISCO_LMI); fr_hard_header(&skb, LMI_CISCO_DLCI); } else { - skb->protocol = cpu_to_be16(NLPID_CCITT_ANSI_LMI); fr_hard_header(&skb, LMI_CCITT_ANSI_DLCI); } data = skb_tail_pointer(skb);