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Miller" , Jakub Kicinski , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Krzysztof Halasa Cc: Xie He Subject: [PATCH net-next] drivers/net/wan/hdlc_fr: Improve fr_rx and add support for any Ethertype Date: Fri, 16 Oct 2020 22:19:51 -0700 Message-Id: <20201017051951.363514-1-xie.he.0141@gmail.com> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org X-Patchwork-Delegate: kuba@kernel.org 1. Change the fr_rx function to make this driver support any Ethertype when receiving. (This driver is already able to handle any Ethertype when sending.) Originally in the fr_rx function, the code that parses the long (10-byte) header only recognizes a few Ethertype values and drops frames with other Ethertype values. This patch replaces this code to make fr_rx support any Ethertype. This patch also creates a new function fr_snap_parse as part of the new code. 2. Change the use of the "dev" variable in fr_rx. Originally we do "dev = something", and then at the end do "if (dev) skb->dev = dev". Now we do "if (something) skb->dev = something", then at the end do "dev = skb->dev". This is to make the logic of our code consistent with eth_type_trans (which we call). The eth_type_trans function expects a non-NULL pointer as a parameter and assigns it directly to skb->dev. 3. Change the initial skb->len check in fr_fx from "<= 4" to "< 4". At first we only need to ensure a 4-byte header is present. We indeed normally need the 5th byte, too, but it'd be more logical to check its existence when we actually need it. Also add an fh->ea2 check to the initial checks in fr_fx. fh->ea2 == 1 means the second address byte is the final address byte. We only support the case where the address length is 2 bytes. 4. Use "goto rx_drop" whenever we need to drop a valid frame. Cc: Krzysztof Halasa Signed-off-by: Xie He --- drivers/net/wan/hdlc_fr.c | 119 +++++++++++++++++++++++--------------- 1 file changed, 73 insertions(+), 46 deletions(-) diff --git a/drivers/net/wan/hdlc_fr.c b/drivers/net/wan/hdlc_fr.c index 409e5a7ad8e2..e95efc14bc97 100644 --- a/drivers/net/wan/hdlc_fr.c +++ b/drivers/net/wan/hdlc_fr.c @@ -871,6 +871,45 @@ static int fr_lmi_recv(struct net_device *dev, struct sk_buff *skb) return 0; } +static int fr_snap_parse(struct sk_buff *skb, struct pvc_device *pvc) +{ + /* OUI 00-00-00 indicates an Ethertype follows */ + if (skb->data[0] == 0x00 && + skb->data[1] == 0x00 && + skb->data[2] == 0x00) { + if (!pvc->main) + return -1; + skb->dev = pvc->main; + skb->protocol = *(__be16 *)(skb->data + 3); /* Ethertype */ + skb_pull(skb, 5); + skb_reset_mac_header(skb); + return 0; + + /* OUI 00-80-C2 stands for the 802.1 organization */ + } else if (skb->data[0] == 0x00 && + skb->data[1] == 0x80 && + skb->data[2] == 0xC2) { + /* PID 00-07 stands for Ethernet frames without FCS */ + if (skb->data[3] == 0x00 && + skb->data[4] == 0x07) { + if (!pvc->ether) + return -1; + skb_pull(skb, 5); + if (skb->len < ETH_HLEN) + return -1; + skb->protocol = eth_type_trans(skb, pvc->ether); + return 0; + + /* PID unsupported */ + } else { + return -1; + } + + /* OUI unsupported */ + } else { + return -1; + } +} static int fr_rx(struct sk_buff *skb) { @@ -880,9 +919,9 @@ static int fr_rx(struct sk_buff *skb) u8 *data = skb->data; u16 dlci; struct pvc_device *pvc; - struct net_device *dev = NULL; + struct net_device *dev; - if (skb->len <= 4 || fh->ea1 || data[2] != FR_UI) + if (skb->len < 4 || fh->ea1 || !fh->ea2 || data[2] != FR_UI) goto rx_error; dlci = q922_to_dlci(skb->data); @@ -904,8 +943,7 @@ static int fr_rx(struct sk_buff *skb) netdev_info(frad, "No PVC for received frame's DLCI %d\n", dlci); #endif - dev_kfree_skb_any(skb); - return NET_RX_DROP; + goto rx_drop; } if (pvc->state.fecn != fh->fecn) { @@ -931,63 +969,52 @@ static int fr_rx(struct sk_buff *skb) } if (data[3] == NLPID_IP) { + if (!pvc->main) + goto rx_drop; skb_pull(skb, 4); /* Remove 4-byte header (hdr, UI, NLPID) */ - dev = pvc->main; + skb->dev = pvc->main; skb->protocol = htons(ETH_P_IP); + skb_reset_mac_header(skb); } else if (data[3] == NLPID_IPV6) { + if (!pvc->main) + goto rx_drop; skb_pull(skb, 4); /* Remove 4-byte header (hdr, UI, NLPID) */ - dev = pvc->main; + skb->dev = pvc->main; skb->protocol = htons(ETH_P_IPV6); + skb_reset_mac_header(skb); - } else if (skb->len > 10 && data[3] == FR_PAD && - data[4] == NLPID_SNAP && data[5] == FR_PAD) { - u16 oui = ntohs(*(__be16*)(data + 6)); - u16 pid = ntohs(*(__be16*)(data + 8)); - skb_pull(skb, 10); - - switch ((((u32)oui) << 16) | pid) { - case ETH_P_ARP: /* routed frame with SNAP */ - case ETH_P_IPX: - case ETH_P_IP: /* a long variant */ - case ETH_P_IPV6: - dev = pvc->main; - skb->protocol = htons(pid); - break; - - case 0x80C20007: /* bridged Ethernet frame */ - if ((dev = pvc->ether) != NULL) - skb->protocol = eth_type_trans(skb, dev); - break; - - default: - netdev_info(frad, "Unsupported protocol, OUI=%x PID=%x\n", - oui, pid); - dev_kfree_skb_any(skb); - return NET_RX_DROP; + } else if (data[3] == FR_PAD) { + if (skb->len < 5) + goto rx_error; + if (data[4] == NLPID_SNAP) { /* A SNAP header follows */ + skb_pull(skb, 5); + if (skb->len < 5) /* Incomplete SNAP header */ + goto rx_error; + if (fr_snap_parse(skb, pvc)) + goto rx_drop; + } else { + goto rx_drop; } + } else { netdev_info(frad, "Unsupported protocol, NLPID=%x length=%i\n", data[3], skb->len); - dev_kfree_skb_any(skb); - return NET_RX_DROP; + goto rx_drop; } - if (dev) { - dev->stats.rx_packets++; /* PVC traffic */ - dev->stats.rx_bytes += skb->len; - if (pvc->state.becn) - dev->stats.rx_compressed++; - skb->dev = dev; - netif_rx(skb); - return NET_RX_SUCCESS; - } else { - dev_kfree_skb_any(skb); - return NET_RX_DROP; - } + dev = skb->dev; + dev->stats.rx_packets++; /* PVC traffic */ + dev->stats.rx_bytes += skb->len; + if (pvc->state.becn) + dev->stats.rx_compressed++; + netif_rx(skb); + return NET_RX_SUCCESS; - rx_error: +rx_error: frad->stats.rx_errors++; /* Mark error */ +rx_drop: + frad->stats.rx_dropped++; dev_kfree_skb_any(skb); return NET_RX_DROP; }