diff options
Diffstat (limited to 'drivers/net/pppopns.c')
| -rw-r--r-- | drivers/net/pppopns.c | 87 |
1 files changed, 79 insertions, 8 deletions
diff --git a/drivers/net/pppopns.c b/drivers/net/pppopns.c index 298097127c90..fb8198447938 100644 --- a/drivers/net/pppopns.c +++ b/drivers/net/pppopns.c @@ -16,11 +16,14 @@ /* This driver handles PPTP data packets between a RAW socket and a PPP channel. * The socket is created in the kernel space and connected to the same address - * of the control socket. To keep things simple, packets are always sent with - * sequence but without acknowledgement. This driver should work on both IPv4 - * and IPv6. */ + * of the control socket. Outgoing packets are always sent with sequences but + * without acknowledgements. Incoming packets with sequences are reordered + * within a sliding window of one second. Currently reordering only happens when + * a packet is received. It is done for simplicity since no additional locks or + * threads are required. This driver should work on both IPv4 and IPv6. */ #include <linux/module.h> +#include <linux/jiffies.h> #include <linux/workqueue.h> #include <linux/skbuff.h> #include <linux/file.h> @@ -52,21 +55,35 @@ struct header { __u32 sequence; } __attribute__((packed)); +struct meta { + __u32 sequence; + __u32 timestamp; +}; + +static inline struct meta *skb_meta(struct sk_buff *skb) +{ + return (struct meta *)skb->cb; +} + +/******************************************************************************/ + static int pppopns_recv_core(struct sock *sk_raw, struct sk_buff *skb) { struct sock *sk = (struct sock *)sk_raw->sk_user_data; struct pppopns_opt *opt = &pppox_sk(sk)->proto.pns; + struct meta *meta = skb_meta(skb); + __u32 now = jiffies; struct header *hdr; /* Skip transport header */ skb_pull(skb, skb_transport_header(skb) - skb->data); - /* Drop the packet if it is too short. */ + /* Drop the packet if GRE header is missing. */ if (skb->len < GRE_HEADER_SIZE) goto drop; + hdr = (struct header *)skb->data; /* Check the header. */ - hdr = (struct header *)skb->data; if (hdr->type != PPTP_GRE_TYPE || hdr->call != opt->local || (hdr->bits & PPTP_GRE_BITS_MASK) != PPTP_GRE_BITS) goto drop; @@ -81,6 +98,13 @@ static int pppopns_recv_core(struct sock *sk_raw, struct sk_buff *skb) if (skb->len != ntohs(hdr->length)) goto drop; + /* Check the sequence if it is present. */ + if (hdr->bits & PPTP_GRE_SEQ_BIT) { + meta->sequence = ntohl(hdr->sequence); + if ((__s32)(meta->sequence - opt->recv_sequence) < 0) + goto drop; + } + /* Skip PPP address and control if they are present. */ if (skb->len >= 2 && skb->data[0] == PPP_ADDR && skb->data[1] == PPP_CTRL) @@ -90,7 +114,53 @@ static int pppopns_recv_core(struct sock *sk_raw, struct sk_buff *skb) if (skb->len >= 1 && skb->data[0] & 1) skb_push(skb, 1)[0] = 0; - /* Finally, deliver the packet to PPP channel. */ + /* Drop the packet if PPP protocol is missing. */ + if (skb->len < 2) + goto drop; + + /* Perform reordering if sequencing is enabled. */ + if (hdr->bits & PPTP_GRE_SEQ_BIT) { + struct sk_buff *skb1; + + /* Insert the packet into receive queue in order. */ + skb_set_owner_r(skb, sk); + skb_queue_walk(&sk->sk_receive_queue, skb1) { + struct meta *meta1 = skb_meta(skb1); + __s32 order = meta->sequence - meta1->sequence; + if (order == 0) + goto drop; + if (order < 0) { + meta->timestamp = meta1->timestamp; + skb_insert(skb1, skb, &sk->sk_receive_queue); + skb = NULL; + break; + } + } + if (skb) { + meta->timestamp = now; + skb_queue_tail(&sk->sk_receive_queue, skb); + } + + /* Remove packets from receive queue as long as + * 1. the receive buffer is full, + * 2. they are queued longer than one second, or + * 3. there are no missing packets before them. */ + skb_queue_walk_safe(&sk->sk_receive_queue, skb, skb1) { + meta = skb_meta(skb); + if (atomic_read(&sk->sk_rmem_alloc) < sk->sk_rcvbuf && + now - meta->timestamp < HZ && + meta->sequence != opt->recv_sequence) + break; + skb_unlink(skb, &sk->sk_receive_queue); + opt->recv_sequence = meta->sequence + 1; + skb_orphan(skb); + ppp_input(&pppox_sk(sk)->chan, skb); + } + return NET_RX_SUCCESS; + } + + /* Flush receive queue if sequencing is disabled. */ + skb_queue_purge(&sk->sk_receive_queue); skb_orphan(skb); ppp_input(&pppox_sk(sk)->chan, skb); return NET_RX_SUCCESS; @@ -151,8 +221,8 @@ static int pppopns_xmit(struct ppp_channel *chan, struct sk_buff *skb) hdr->type = PPTP_GRE_TYPE; hdr->length = htons(length); hdr->call = opt->remote; - hdr->sequence = htonl(opt->sequence); - opt->sequence++; + hdr->sequence = htonl(opt->xmit_sequence); + opt->xmit_sequence++; /* Now send the packet via the delivery queue. */ skb_set_owner_w(skb, sk_raw); @@ -261,6 +331,7 @@ static int pppopns_release(struct socket *sock) if (sk->sk_state != PPPOX_NONE) { struct sock *sk_raw = (struct sock *)pppox_sk(sk)->chan.private; lock_sock(sk_raw); + skb_queue_purge(&sk->sk_receive_queue); pppox_unbind_sock(sk); sk_raw->sk_data_ready = pppox_sk(sk)->proto.pns.data_ready; sk_raw->sk_backlog_rcv = pppox_sk(sk)->proto.pns.backlog_rcv; |