From 583d5333ed7dcdc0c7a3f8ec8b818b7ae4a59e8e Mon Sep 17 00:00:00 2001 From: Xie He Date: Sat, 31 Oct 2020 11:10:39 -0700 Subject: [PATCH 1/5] net: hdlc_fr: Simpify fr_rx by using "goto rx_drop" to drop frames When the fr_rx function drops a received frame (because the protocol type is not supported, or because the PVC virtual device that corresponds to the DLCI number and the protocol type doesn't exist), the function frees the skb and returns. The code for freeing the skb and returning is repeated several times, this patch uses "goto rx_drop" to replace them so that the code looks cleaner. Cc: Krzysztof Halasa Cc: Willem de Bruijn Signed-off-by: Xie He Signed-off-by: Jakub Kicinski --- drivers/net/wan/hdlc_fr.c | 15 ++++++--------- 1 file changed, 6 insertions(+), 9 deletions(-) diff --git a/drivers/net/wan/hdlc_fr.c b/drivers/net/wan/hdlc_fr.c index 409e5a7ad8e2..4db0e01b96a9 100644 --- a/drivers/net/wan/hdlc_fr.c +++ b/drivers/net/wan/hdlc_fr.c @@ -904,8 +904,7 @@ 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) { @@ -963,14 +962,12 @@ static int fr_rx(struct sk_buff *skb) default: netdev_info(frad, "Unsupported protocol, OUI=%x PID=%x\n", oui, pid); - dev_kfree_skb_any(skb); - return NET_RX_DROP; + 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) { @@ -982,12 +979,12 @@ static int fr_rx(struct sk_buff *skb) netif_rx(skb); return NET_RX_SUCCESS; } else { - dev_kfree_skb_any(skb); - return NET_RX_DROP; + goto rx_drop; } - rx_error: +rx_error: frad->stats.rx_errors++; /* Mark error */ +rx_drop: dev_kfree_skb_any(skb); return NET_RX_DROP; } From 14b20704a18062249903a7a930e27c4452bc56bc Mon Sep 17 00:00:00 2001 From: Xie He Date: Sat, 31 Oct 2020 11:10:40 -0700 Subject: [PATCH 2/5] net: hdlc_fr: Change the use of "dev" in fr_rx to make the code cleaner The eth_type_trans function is called when we receive frames carrying Ethernet frames. This function expects a non-NULL pointer as an argument, and assigns it directly to skb->dev. However, the code handling other types of frames first assigns the pointer to "dev", and then at the end checks whether the value is NULL, and if it is not NULL, assigns it to skb->dev. The two flows are different. Mixing them in this function makes the code messy. It's better that we convert the second flow to align with how eth_type_trans does things. So this patch changes the code to: first make sure the pointer is not NULL, then assign it directly to skb->dev. "dev" is no longer needed until the end where we use it to update stats. Cc: Krzysztof Halasa Cc: Willem de Bruijn Signed-off-by: Xie He Signed-off-by: Jakub Kicinski --- drivers/net/wan/hdlc_fr.c | 37 ++++++++++++++++++++----------------- 1 file changed, 20 insertions(+), 17 deletions(-) diff --git a/drivers/net/wan/hdlc_fr.c b/drivers/net/wan/hdlc_fr.c index 4db0e01b96a9..71ee9b60d91b 100644 --- a/drivers/net/wan/hdlc_fr.c +++ b/drivers/net/wan/hdlc_fr.c @@ -880,7 +880,7 @@ 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) goto rx_error; @@ -930,13 +930,17 @@ 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); } 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); } else if (skb->len > 10 && data[3] == FR_PAD && @@ -950,13 +954,16 @@ static int fr_rx(struct sk_buff *skb) case ETH_P_IPX: case ETH_P_IP: /* a long variant */ case ETH_P_IPV6: - dev = pvc->main; + if (!pvc->main) + goto rx_drop; + skb->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); + if (!pvc->ether) + goto rx_drop; + skb->protocol = eth_type_trans(skb, pvc->ether); break; default: @@ -970,17 +977,13 @@ static int fr_rx(struct sk_buff *skb) 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 { - goto 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: frad->stats.rx_errors++; /* Mark error */ From efc790394f8ac7645d80c44f9cc110779428fe7b Mon Sep 17 00:00:00 2001 From: Xie He Date: Sat, 31 Oct 2020 11:10:41 -0700 Subject: [PATCH 3/5] net: hdlc_fr: Do skb_reset_mac_header for skbs received on normal PVC devices When an skb is received on a normal (non-Ethernet-emulating) PVC device, call skb_reset_mac_header before we pass it to upper layers. This is because normal PVC devices don't have header_ops, so any header we have would not be visible to upper layer code when sending, so the header shouldn't be visible to upper layer code when receiving, either. Cc: Krzysztof Halasa Cc: Willem de Bruijn Signed-off-by: Xie He Signed-off-by: Jakub Kicinski --- drivers/net/wan/hdlc_fr.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/net/wan/hdlc_fr.c b/drivers/net/wan/hdlc_fr.c index 71ee9b60d91b..eb83116aa9df 100644 --- a/drivers/net/wan/hdlc_fr.c +++ b/drivers/net/wan/hdlc_fr.c @@ -935,6 +935,7 @@ static int fr_rx(struct sk_buff *skb) skb_pull(skb, 4); /* Remove 4-byte header (hdr, UI, NLPID) */ skb->dev = pvc->main; skb->protocol = htons(ETH_P_IP); + skb_reset_mac_header(skb); } else if (data[3] == NLPID_IPV6) { if (!pvc->main) @@ -942,6 +943,7 @@ static int fr_rx(struct sk_buff *skb) skb_pull(skb, 4); /* Remove 4-byte header (hdr, UI, NLPID) */ 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) { @@ -958,6 +960,7 @@ static int fr_rx(struct sk_buff *skb) goto rx_drop; skb->dev = pvc->main; skb->protocol = htons(pid); + skb_reset_mac_header(skb); break; case 0x80C20007: /* bridged Ethernet frame */ From 77124c4463d45083e69b7284415467737f31f76b Mon Sep 17 00:00:00 2001 From: Xie He Date: Sat, 31 Oct 2020 11:10:42 -0700 Subject: [PATCH 4/5] net: hdlc_fr: Improve the initial checks when we receive an skb 1. Change the skb->len check 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 and cleaner to check its existence when we actually need it. 2. Add an fh->ea2 check to the initial checks in fr_rx. 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. Cc: Krzysztof Halasa Signed-off-by: Xie He Acked-by: Willem de Bruijn Signed-off-by: Jakub Kicinski --- drivers/net/wan/hdlc_fr.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/net/wan/hdlc_fr.c b/drivers/net/wan/hdlc_fr.c index eb83116aa9df..98444f1d8cc3 100644 --- a/drivers/net/wan/hdlc_fr.c +++ b/drivers/net/wan/hdlc_fr.c @@ -882,7 +882,7 @@ static int fr_rx(struct sk_buff *skb) struct pvc_device *pvc; 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); From 54b77a77e30a5170a25cfd2f211e08ea5a6c0c4c Mon Sep 17 00:00:00 2001 From: Xie He Date: Sat, 31 Oct 2020 11:10:43 -0700 Subject: [PATCH 5/5] net: hdlc_fr: Add support for any Ethertype Change the fr_rx function to make this driver support any Ethertype when receiving skbs on normal (non-Ethernet-emulating) PVC devices. (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. Cc: Krzysztof Halasa Signed-off-by: Xie He Acked-by: Willem de Bruijn Signed-off-by: Jakub Kicinski --- drivers/net/wan/hdlc_fr.c | 75 +++++++++++++++++++++++++-------------- 1 file changed, 49 insertions(+), 26 deletions(-) diff --git a/drivers/net/wan/hdlc_fr.c b/drivers/net/wan/hdlc_fr.c index 98444f1d8cc3..0720f5f92caa 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) { @@ -945,35 +984,19 @@ static int fr_rx(struct sk_buff *skb) 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: - if (!pvc->main) + } 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; - skb->dev = pvc->main; - skb->protocol = htons(pid); - skb_reset_mac_header(skb); - break; - - case 0x80C20007: /* bridged Ethernet frame */ - if (!pvc->ether) - goto rx_drop; - skb->protocol = eth_type_trans(skb, pvc->ether); - break; - - default: - netdev_info(frad, "Unsupported protocol, OUI=%x PID=%x\n", - oui, pid); + } else { goto rx_drop; } + } else { netdev_info(frad, "Unsupported protocol, NLPID=%x length=%i\n", data[3], skb->len);