Merge tag 'audit-pr-20190702' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoor...
[platform/kernel/linux-starfive.git] / net / x25 / x25_out.c
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  *      X.25 Packet Layer release 002
4  *
5  *      This is ALPHA test software. This code may break your machine,
6  *      randomly fail to work with new releases, misbehave and/or generally
7  *      screw up. It might even work.
8  *
9  *      This code REQUIRES 2.1.15 or higher
10  *
11  *      History
12  *      X.25 001        Jonathan Naylor Started coding.
13  *      X.25 002        Jonathan Naylor New timer architecture.
14  *      2000-09-04      Henner Eisen    Prevented x25_output() skb leakage.
15  *      2000-10-27      Henner Eisen    MSG_DONTWAIT for fragment allocation.
16  *      2000-11-10      Henner Eisen    x25_send_iframe(): re-queued frames
17  *                                      needed cleaned seq-number fields.
18  */
19
20 #include <linux/slab.h>
21 #include <linux/socket.h>
22 #include <linux/kernel.h>
23 #include <linux/string.h>
24 #include <linux/skbuff.h>
25 #include <net/sock.h>
26 #include <net/x25.h>
27
28 static int x25_pacsize_to_bytes(unsigned int pacsize)
29 {
30         int bytes = 1;
31
32         if (!pacsize)
33                 return 128;
34
35         while (pacsize-- > 0)
36                 bytes *= 2;
37
38         return bytes;
39 }
40
41 /*
42  *      This is where all X.25 information frames pass.
43  *
44  *      Returns the amount of user data bytes sent on success
45  *      or a negative error code on failure.
46  */
47 int x25_output(struct sock *sk, struct sk_buff *skb)
48 {
49         struct sk_buff *skbn;
50         unsigned char header[X25_EXT_MIN_LEN];
51         int err, frontlen, len;
52         int sent=0, noblock = X25_SKB_CB(skb)->flags & MSG_DONTWAIT;
53         struct x25_sock *x25 = x25_sk(sk);
54         int header_len = x25->neighbour->extended ? X25_EXT_MIN_LEN :
55                                                     X25_STD_MIN_LEN;
56         int max_len = x25_pacsize_to_bytes(x25->facilities.pacsize_out);
57
58         if (skb->len - header_len > max_len) {
59                 /* Save a copy of the Header */
60                 skb_copy_from_linear_data(skb, header, header_len);
61                 skb_pull(skb, header_len);
62
63                 frontlen = skb_headroom(skb);
64
65                 while (skb->len > 0) {
66                         release_sock(sk);
67                         skbn = sock_alloc_send_skb(sk, frontlen + max_len,
68                                                    noblock, &err);
69                         lock_sock(sk);
70                         if (!skbn) {
71                                 if (err == -EWOULDBLOCK && noblock){
72                                         kfree_skb(skb);
73                                         return sent;
74                                 }
75                                 SOCK_DEBUG(sk, "x25_output: fragment alloc"
76                                                " failed, err=%d, %d bytes "
77                                                "sent\n", err, sent);
78                                 return err;
79                         }
80
81                         skb_reserve(skbn, frontlen);
82
83                         len = max_len > skb->len ? skb->len : max_len;
84
85                         /* Copy the user data */
86                         skb_copy_from_linear_data(skb, skb_put(skbn, len), len);
87                         skb_pull(skb, len);
88
89                         /* Duplicate the Header */
90                         skb_push(skbn, header_len);
91                         skb_copy_to_linear_data(skbn, header, header_len);
92
93                         if (skb->len > 0) {
94                                 if (x25->neighbour->extended)
95                                         skbn->data[3] |= X25_EXT_M_BIT;
96                                 else
97                                         skbn->data[2] |= X25_STD_M_BIT;
98                         }
99
100                         skb_queue_tail(&sk->sk_write_queue, skbn);
101                         sent += len;
102                 }
103
104                 kfree_skb(skb);
105         } else {
106                 skb_queue_tail(&sk->sk_write_queue, skb);
107                 sent = skb->len - header_len;
108         }
109         return sent;
110 }
111
112 /*
113  *      This procedure is passed a buffer descriptor for an iframe. It builds
114  *      the rest of the control part of the frame and then writes it out.
115  */
116 static void x25_send_iframe(struct sock *sk, struct sk_buff *skb)
117 {
118         struct x25_sock *x25 = x25_sk(sk);
119
120         if (!skb)
121                 return;
122
123         if (x25->neighbour->extended) {
124                 skb->data[2]  = (x25->vs << 1) & 0xFE;
125                 skb->data[3] &= X25_EXT_M_BIT;
126                 skb->data[3] |= (x25->vr << 1) & 0xFE;
127         } else {
128                 skb->data[2] &= X25_STD_M_BIT;
129                 skb->data[2] |= (x25->vs << 1) & 0x0E;
130                 skb->data[2] |= (x25->vr << 5) & 0xE0;
131         }
132
133         x25_transmit_link(skb, x25->neighbour);
134 }
135
136 void x25_kick(struct sock *sk)
137 {
138         struct sk_buff *skb, *skbn;
139         unsigned short start, end;
140         int modulus;
141         struct x25_sock *x25 = x25_sk(sk);
142
143         if (x25->state != X25_STATE_3)
144                 return;
145
146         /*
147          *      Transmit interrupt data.
148          */
149         if (skb_peek(&x25->interrupt_out_queue) != NULL &&
150                 !test_and_set_bit(X25_INTERRUPT_FLAG, &x25->flags)) {
151
152                 skb = skb_dequeue(&x25->interrupt_out_queue);
153                 x25_transmit_link(skb, x25->neighbour);
154         }
155
156         if (x25->condition & X25_COND_PEER_RX_BUSY)
157                 return;
158
159         if (!skb_peek(&sk->sk_write_queue))
160                 return;
161
162         modulus = x25->neighbour->extended ? X25_EMODULUS : X25_SMODULUS;
163
164         start   = skb_peek(&x25->ack_queue) ? x25->vs : x25->va;
165         end     = (x25->va + x25->facilities.winsize_out) % modulus;
166
167         if (start == end)
168                 return;
169
170         x25->vs = start;
171
172         /*
173          * Transmit data until either we're out of data to send or
174          * the window is full.
175          */
176
177         skb = skb_dequeue(&sk->sk_write_queue);
178
179         do {
180                 if ((skbn = skb_clone(skb, GFP_ATOMIC)) == NULL) {
181                         skb_queue_head(&sk->sk_write_queue, skb);
182                         break;
183                 }
184
185                 skb_set_owner_w(skbn, sk);
186
187                 /*
188                  * Transmit the frame copy.
189                  */
190                 x25_send_iframe(sk, skbn);
191
192                 x25->vs = (x25->vs + 1) % modulus;
193
194                 /*
195                  * Requeue the original data frame.
196                  */
197                 skb_queue_tail(&x25->ack_queue, skb);
198
199         } while (x25->vs != end &&
200                  (skb = skb_dequeue(&sk->sk_write_queue)) != NULL);
201
202         x25->vl         = x25->vr;
203         x25->condition &= ~X25_COND_ACK_PENDING;
204
205         x25_stop_timer(sk);
206 }
207
208 /*
209  * The following routines are taken from page 170 of the 7th ARRL Computer
210  * Networking Conference paper, as is the whole state machine.
211  */
212
213 void x25_enquiry_response(struct sock *sk)
214 {
215         struct x25_sock *x25 = x25_sk(sk);
216
217         if (x25->condition & X25_COND_OWN_RX_BUSY)
218                 x25_write_internal(sk, X25_RNR);
219         else
220                 x25_write_internal(sk, X25_RR);
221
222         x25->vl         = x25->vr;
223         x25->condition &= ~X25_COND_ACK_PENDING;
224
225         x25_stop_timer(sk);
226 }