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Commit | Line | Data |
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2874c5fd | 1 | // SPDX-License-Identifier: GPL-2.0-or-later |
1da177e4 LT |
2 | /* |
3 | * SNAP data link layer. Derived from 802.2 | |
4 | * | |
113aa838 | 5 | * Alan Cox <alan@lxorguk.ukuu.org.uk>, |
1da177e4 LT |
6 | * from the 802.2 layer by Greg Page. |
7 | * Merged in additions from Greg Page's psnap.c. | |
1da177e4 LT |
8 | */ |
9 | ||
10 | #include <linux/module.h> | |
11 | #include <linux/netdevice.h> | |
12 | #include <linux/skbuff.h> | |
5a0e3ad6 | 13 | #include <linux/slab.h> |
1da177e4 LT |
14 | #include <net/datalink.h> |
15 | #include <net/llc.h> | |
16 | #include <net/psnap.h> | |
17 | #include <linux/mm.h> | |
18 | #include <linux/in.h> | |
19 | #include <linux/init.h> | |
82524746 | 20 | #include <linux/rculist.h> |
1da177e4 LT |
21 | |
22 | static LIST_HEAD(snap_list); | |
23 | static DEFINE_SPINLOCK(snap_lock); | |
24 | static struct llc_sap *snap_sap; | |
25 | ||
26 | /* | |
27 | * Find a snap client by matching the 5 bytes. | |
28 | */ | |
7ca98fa2 | 29 | static struct datalink_proto *find_snap_client(const unsigned char *desc) |
1da177e4 | 30 | { |
1da177e4 LT |
31 | struct datalink_proto *proto = NULL, *p; |
32 | ||
696adfe8 | 33 | list_for_each_entry_rcu(p, &snap_list, node) { |
1da177e4 LT |
34 | if (!memcmp(p->type, desc, 5)) { |
35 | proto = p; | |
36 | break; | |
37 | } | |
38 | } | |
39 | return proto; | |
40 | } | |
41 | ||
42 | /* | |
43 | * A SNAP packet has arrived | |
44 | */ | |
45 | static int snap_rcv(struct sk_buff *skb, struct net_device *dev, | |
f2ccd8fa | 46 | struct packet_type *pt, struct net_device *orig_dev) |
1da177e4 LT |
47 | { |
48 | int rc = 1; | |
49 | struct datalink_proto *proto; | |
50 | static struct packet_type snap_packet_type = { | |
09640e63 | 51 | .type = cpu_to_be16(ETH_P_SNAP), |
1da177e4 LT |
52 | }; |
53 | ||
d92a7db7 HX |
54 | if (unlikely(!pskb_may_pull(skb, 5))) |
55 | goto drop; | |
56 | ||
1da177e4 | 57 | rcu_read_lock(); |
9c70220b | 58 | proto = find_snap_client(skb_transport_header(skb)); |
1da177e4 LT |
59 | if (proto) { |
60 | /* Pass the frame on. */ | |
b0e380b1 | 61 | skb->transport_header += 5; |
cbb042f9 | 62 | skb_pull_rcsum(skb, 5); |
f2ccd8fa | 63 | rc = proto->rcvfunc(skb, dev, &snap_packet_type, orig_dev); |
1da177e4 | 64 | } |
1da177e4 | 65 | rcu_read_unlock(); |
d92a7db7 HX |
66 | |
67 | if (unlikely(!proto)) | |
68 | goto drop; | |
69 | ||
70 | out: | |
1da177e4 | 71 | return rc; |
d92a7db7 HX |
72 | |
73 | drop: | |
74 | kfree_skb(skb); | |
75 | goto out; | |
1da177e4 LT |
76 | } |
77 | ||
78 | /* | |
79 | * Put a SNAP header on a frame and pass to 802.2 | |
80 | */ | |
81 | static int snap_request(struct datalink_proto *dl, | |
82 | struct sk_buff *skb, u8 *dest) | |
83 | { | |
84 | memcpy(skb_push(skb, 5), dl->type, 5); | |
85 | llc_build_and_send_ui_pkt(snap_sap, skb, dest, snap_sap->laddr.lsap); | |
86 | return 0; | |
87 | } | |
88 | ||
89 | /* | |
90 | * Set up the SNAP layer | |
91 | */ | |
92 | EXPORT_SYMBOL(register_snap_client); | |
93 | EXPORT_SYMBOL(unregister_snap_client); | |
94 | ||
0117cfab | 95 | static const char snap_err_msg[] __initconst = |
1da177e4 LT |
96 | KERN_CRIT "SNAP - unable to register with 802.2\n"; |
97 | ||
98 | static int __init snap_init(void) | |
99 | { | |
100 | snap_sap = llc_sap_open(0xAA, snap_rcv); | |
0117cfab | 101 | if (!snap_sap) { |
1da177e4 | 102 | printk(snap_err_msg); |
0117cfab SH |
103 | return -EBUSY; |
104 | } | |
1da177e4 LT |
105 | |
106 | return 0; | |
107 | } | |
108 | ||
109 | module_init(snap_init); | |
110 | ||
111 | static void __exit snap_exit(void) | |
112 | { | |
6e2144b7 | 113 | llc_sap_put(snap_sap); |
1da177e4 LT |
114 | } |
115 | ||
116 | module_exit(snap_exit); | |
117 | ||
118 | ||
119 | /* | |
120 | * Register SNAP clients. We don't yet use this for IP. | |
121 | */ | |
7ca98fa2 | 122 | struct datalink_proto *register_snap_client(const unsigned char *desc, |
1da177e4 | 123 | int (*rcvfunc)(struct sk_buff *, |
9afa0949 | 124 | struct net_device *, |
f2ccd8fa DM |
125 | struct packet_type *, |
126 | struct net_device *)) | |
1da177e4 LT |
127 | { |
128 | struct datalink_proto *proto = NULL; | |
129 | ||
130 | spin_lock_bh(&snap_lock); | |
131 | ||
132 | if (find_snap_client(desc)) | |
133 | goto out; | |
134 | ||
135 | proto = kmalloc(sizeof(*proto), GFP_ATOMIC); | |
136 | if (proto) { | |
7ca98fa2 | 137 | memcpy(proto->type, desc, 5); |
1da177e4 LT |
138 | proto->rcvfunc = rcvfunc; |
139 | proto->header_length = 5 + 3; /* snap + 802.2 */ | |
140 | proto->request = snap_request; | |
141 | list_add_rcu(&proto->node, &snap_list); | |
142 | } | |
143 | out: | |
144 | spin_unlock_bh(&snap_lock); | |
145 | ||
1da177e4 LT |
146 | return proto; |
147 | } | |
148 | ||
149 | /* | |
150 | * Unregister SNAP clients. Protocols no longer want to play with us ... | |
151 | */ | |
152 | void unregister_snap_client(struct datalink_proto *proto) | |
153 | { | |
154 | spin_lock_bh(&snap_lock); | |
155 | list_del_rcu(&proto->node); | |
156 | spin_unlock_bh(&snap_lock); | |
157 | ||
158 | synchronize_net(); | |
159 | ||
160 | kfree(proto); | |
161 | } | |
162 | ||
163 | MODULE_LICENSE("GPL"); |